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Sample records for muscle working capacity

  1. Work capacity and metabolic and morphologic characteristics of the human quadriceps muscle in response to unloading

    NASA Technical Reports Server (NTRS)

    Berg, H. E.; Dudley, G. A.; Hather, B.; Tesch, P. A.

    1993-01-01

    The response of skeletal muscle to unweighting was studied in six healthy males who were subjected to four weeks of lowerlimb suspension. They performed three bouts of 30 consecutive maximal concentric knee extensions, before unloading and the day after (POST 1), 4 days after (POST 2) and 7 weeks after (REC) resumed weight-bearing. Peak torque of each contraction was recorded and work was calculated as the mean of the average peak torque for the three bouts and fatigability was measured as the decline in average peak torque over bouts. Needle biopsies were obtained from m. vastus lateralis of each limb before and at POST 1. Muscle fibre type composition and area, capillarity and the enzyme activities of citrate synthase (CS) and phosphofructokinase (PFK) were subsequently analysed. Mean average peak torque for the three bouts at POST1, POST2 and REC was reduced (P < 0.05) by 17, 13 and 7%, respectively. Fatigability was greater (P < 0.05) at POST2 than before unloading. Type I, IIA and IIB percentage, Type I and II area and capillaries per fibre of Type I and II did not change (P > 0.05) in response to unloading. The activity of CS, but not PFK, decreased (P < 0.05) after unloading. The weight-bearing limb showed no changes in the variables measured. The results of this study suggest that this human lowerlimb suspension model produces substantial impairments of work and oxidative capacity of skeletal muscle. The performance decrements are most likely induced by lack of weight-bearing.

  2. Inspiratory muscle training improves cycling time-trial performance and anaerobic work capacity but not critical power.

    PubMed

    Johnson, Michael A; Sharpe, Graham R; Brown, Peter I

    2007-12-01

    We examined whether inspiratory muscle training (IMT) improved cycling time-trial performance and changed the relationship between limit work (W (lim)) and limit time (T (lim)), which is described by the parameters critical power (CP) and anaerobic work capacity (AWC). Eighteen male cyclists were assigned to either a pressure-threshold IMT or sham hypoxic-training placebo (PLC) group. Prior to and following a 6 week intervention subjects completed a 25-km cycling time-trial and three constant-power tests to establish the W (lim)-T (lim) relationship. Constant-power tests were prescribed to elicit exercise intolerance within 3-10 (Ex1), 10-20 (Ex2), and 20-30 (Ex3) min. Maximal inspiratory mouth pressure increased by (mean +/- SD) 17.1 +/- 12.2% following IMT (P < 0.01) and was accompanied by a 2.66 +/- 2.51% improvement in 25-km time-trial performance (P < 0.05); there were no changes following PLC. Constant-power cycling endurance was unchanged following PLC, as was CP (pre vs. post: 249 +/- 32 vs. 250 +/- 32 W) and AWC (30.7 +/- 12.7 vs. 30.1 +/- 12.5 kJ). Following IMT Ex1 and Ex3 cycling endurance improved by 18.3 +/- 15.1 and 15.3 +/- 19.1% (P < 0.05), respectively, CP was unchanged (264 +/- 62 vs. 263 +/- 61 W), but AWC increased from 24.8 +/- 5.6 to 29.0 +/- 8.4 kJ (P < 0.05). In conclusion, these data provide novel evidence that improvements in constant-power and cycling time-trial performance following IMT in cyclists may be explained, in part, by an increase in AWC. PMID:17874123

  3. Advanced work capacity testing.

    PubMed

    Bretz, Károly J; Dános, László; Smudla, Szilvia; Pálosi, Adrienn

    2015-01-01

    The aim of this study is to describe an accurate work capacity testing which can be used in the industry, as well as in rehabilitation process. The first part of this paper is dealing with the NIOSH lifting equation, which is a tool used by occupational health and safety professionals. The second part of this paper summarizes the features and applications of the "ErgoScope" work simulator. Static and dynamic strength of upper and lower limbs, as well as whole body efforts can be measured. The equipment makes it possible to evaluate pushing, pulling, lifting and carrying activities comprising reaching, bending and stooping movements. In the third part of this paper we demonstrate handgrip force data recorded using the "ErgoScope" work simulator comparing with handgrip force data published in the literature. "ErgoScope" work simulator is capable to measure handgrip and pinch forces, suitable to evaluate fine motor skills, hand and finger dexterity, as well as reaction times. PMID:26294589

  4. Non-invasive assessment of phosphate metabolism and oxidative capacity in working skeletal muscle in healthy young Chinese volunteers using (31)P Magnetic Resonance Spectroscopy.

    PubMed

    Li, Ming; Chen, Fei; Wang, Huiting; Wu, Wenbo; Zhang, Xin; Tian, Chuanshuai; Yu, Haiping; Liu, Renyuan; Zhu, Bin; Zhang, Bing; Dai, Zhenyu

    2016-01-01

    Background. Generally, males display greater strength and muscle capacity than females while performing a task. Muscle biopsy is regarded as the reference method of evaluating muscle functions; however, it is invasive and has sampling errors, and is not practical for longitudinal studies and dynamic measurement during excise. In this study, we built an in-house force control and gauge system for quantitatively applying force to quadriceps while the subjects underwent (31)P Magnetic Resonance Spectroscopy ((31)P-MRS); our aim was to investigate if there is a sex difference of phosphate metabolite change in working muscles in young heathy Chinese volunteers. Methods. Volunteers performed knee-extending excises using a force control and gauge system while lying prone in a Philips 3T Magnetic Resonance (MR) scanner. The (31)P-MRS coil was firmly placed under the middle of the quadriceps . (31)P-MRS measurements of inorganic phosphate (Pi), phosphocreatine (PCr) and adenosine triphosphate (ATP) were acquired from quadriceps while subjects were in a state of pre-, during- and post-exercise. The PCr, Pi, PCr/Pi, PCr/ATP, pH, work/energy cost ratio (WE), kPCr and oxidative capacity were compared between males and females. Results. A total of 17 volunteers underwent the study. Males: N = 10, age = 23.30 ± 1.25years; females: N = 7, age = 23.57 ± 0.79 years. In this study, males had significantly greater WE (16.33 ± 6.46 vs. 7.82 ± 2.16, p = 0.002) than females. Among PCr, Pi, PCr/Pi, PCr/ATP, pH, kPCr and oxidative capacity at different exercise status, only PCr/Pi (during-exercise, males = 5.630 ± 1.647, females = 4.014 ± 1.298, p = 0.047), PCr/ATP (during-exercise, males =1.273 ± 0.219, females = 1.523 ± 0.167, p = 0.025), and ATP (post-exercise, males = 24.469 ± 3.911 mmol/kg, females = 18.353 ± 4.818 mmol/kg, p = 0.035) had significant sex differences. Males had significantly greater PCr/Pi, but less PCr/ATP than females during exercise, suggesting males had

  5. Non-invasive assessment of phosphate metabolism and oxidative capacity in working skeletal muscle in healthy young Chinese volunteers using 31P Magnetic Resonance Spectroscopy

    PubMed Central

    Wang, Huiting; Wu, Wenbo; Zhang, Xin; Tian, Chuanshuai; Yu, Haiping; Liu, Renyuan; Zhu, Bin

    2016-01-01

    Background. Generally, males display greater strength and muscle capacity than females while performing a task. Muscle biopsy is regarded as the reference method of evaluating muscle functions; however, it is invasive and has sampling errors, and is not practical for longitudinal studies and dynamic measurement during excise. In this study, we built an in-house force control and gauge system for quantitatively applying force to quadriceps while the subjects underwent 31P Magnetic Resonance Spectroscopy (31P-MRS); our aim was to investigate if there is a sex difference of phosphate metabolite change in working muscles in young heathy Chinese volunteers. Methods. Volunteers performed knee-extending excises using a force control and gauge system while lying prone in a Philips 3T Magnetic Resonance (MR) scanner. The 31P-MRS coil was firmly placed under the middle of the quadriceps . 31P-MRS measurements of inorganic phosphate (Pi), phosphocreatine (PCr) and adenosine triphosphate (ATP) were acquired from quadriceps while subjects were in a state of pre-, during- and post-exercise. The PCr, Pi, PCr/Pi, PCr/ATP, pH, work/energy cost ratio (WE), kPCr and oxidative capacity were compared between males and females. Results. A total of 17 volunteers underwent the study. Males: N = 10, age = 23.30 ± 1.25years; females: N = 7, age = 23.57 ± 0.79 years. In this study, males had significantly greater WE (16.33 ± 6.46 vs. 7.82 ± 2.16, p = 0.002) than females. Among PCr, Pi, PCr/Pi, PCr/ATP, pH, kPCr and oxidative capacity at different exercise status, only PCr/Pi (during-exercise, males = 5.630 ± 1.647, females = 4.014 ± 1.298, p = 0.047), PCr/ATP (during-exercise, males =1.273 ± 0.219, females = 1.523 ± 0.167, p = 0.025), and ATP (post-exercise, males = 24.469 ± 3.911 mmol/kg, females = 18.353 ± 4.818 mmol/kg, p = 0.035) had significant sex differences. Males had significantly greater PCr/Pi, but less PCr/ATP than females during exercise, suggesting males had higher

  6. [Work capacity and aging].

    PubMed

    Costa, G

    2000-01-01

    Maintaining a good work ability depends on satisfactory health and employment status, which is supported by suitable working conditions and correct life styles. From the biological perspective, ageing means a foreseeable progressive and overall deterioration of the various physiological systems, but not of such a kind and severity to consider most people over 50 as too old or unfit for work, as has been shown by several studies that assessed work ability not only in terms of biological age, but of functional age and actual work output. From the physio-pathological perspective, we can observe either illnesses associated with the passage of time or age-related changes that might precipitate diseases, as well as environmental changes that modulate ageing and developmental changes that accelerate or retard ageing. From the practical point of view, it should taken into account that job demands often do not follow the natural biological and functional changes of the individual, consequently the relative work load can be higher in older workers. On the other hand, ageing also means a professional growth in terms of strategic ability, shrewdness, wisdom and experience. The high interindividual variability of physical, mental and social conditions that is observed with the increase in age makes it necessary to adopt flexible and personally tailored measures, as shown by recent surveys in some European countries aimed at reducing age discrimination and work disability, and at promoting work ability by means of actions directed towards both improvement of work organisation and support of psycho-physical conditions of older workers. PMID:11098594

  7. Skeletal Muscle Loading Changes its Regenerative Capacity.

    PubMed

    Teixeira, Eduardo; Duarte, José Alberto

    2016-06-01

    Whenever skeletal muscle insults occur, both by functional impositions or other injury forms, skeletal muscle repair (SMR) follows. The SMR succeeds when proper skeletal muscle regeneration and limited fibrosis ensue. Muscle fiber replenishment by fibrosis negatively affects the tissue quality and functionality and, furthermore, represents the worst post-injury phenotypic adaptation. Acute muscle injury treatment commonly follows the RICE method-rest, ice, compression, and elevation. This immediate immobilization seems to be beneficial to preserving the tissue structure and avoiding further destruction; however, if these interventions are delayed, the risk of muscle atrophy and its deleterious-related effects increase, with resultant impaired SMR. Moreover, a growing body of evidence shows positive skeletal muscle loading (SML) effects during SMR since it seems to effectively increase satellite cells (SCs) in their activation, proliferation, self-renewal, and differentiation capacities. Additionally, recent data show that SML may also influence the functions of other participants in SMR, compelling SMR to achieve less fibrotic accretion and accelerated muscle mass recovery. Moreover, given the SML effects on SCs, it is plausible to consider that these can increase the myofibers' basal myogenic potential. Thus, it seems relevant to scrutinize the possible acute and chronic SML therapeutic and prophylactic effects regarding the SMR process. PMID:26838984

  8. What limits working memory capacity?

    PubMed

    Oberauer, Klaus; Farrell, Simon; Jarrold, Christopher; Lewandowsky, Stephan

    2016-07-01

    We review the evidence for the 3 principal theoretical contenders that vie to explain why and how working memory (WM) capacity is limited. We examine the possibility that capacity limitations arise from temporal decay; we examine whether they might reflect a limitation in cognitive resources; and we ask whether capacity might be limited because of mutual interference of representations in WM. We evaluate each hypothesis against a common set of findings reflecting the capacity limit: The set-size effect and its modulation by domain-specificity and heterogeneity of the memory set; the effects of unfilled retention intervals and of distractor processing in the retention interval; and the pattern of correlates of WM tests. We conclude that-at least for verbal memoranda-a decay explanation is untenable. A resource-based view remains tenable but has difficulty accommodating several findings. The interference approach has its own set of difficulties but accounts best for the set of findings, and therefore, appears to present the most promising approach for future development. (PsycINFO Database Record PMID:26950009

  9. Efficiency of work production by spastic muscles.

    PubMed

    Stoquart, G G; Detrembleur, C; Nielens, H; Lejeune, T M

    2005-12-01

    The present study compared the muscular efficiency in spastic and healthy lower limbs producing the same mechanical work. Sixteen chronic post-stroke hemiparetic and spastic patients and 14 age-matched healthy subjects were submitted to a submaximal stepwise exercise testing on a bicycle ergometer, pedalling with only one lower limb. Net energetic expenditure was computed from oxygen consumption above resting values. Electrical activity of antagonistic muscles in the thigh and in the shank was recorded and co-contraction was defined as the percentage of the pedalling cycle when antagonistic muscles were activated simultaneously. The efficiency was calculated as the ratio between the mechanical work done on the ergometer and the net energetic expenditure. Spasticity was quantitatively evaluated by measuring passive ankle plantar flexor muscle stiffness. The working capacity of the patients' paretic lower limb was very low (<40W). The energy expenditure increased linearly as a function of work intensity, without statistical difference between the patients paretic lower limb (PPL), the patients healthy lower limb (PHL) and the healthy subjects lower limb (HSL). Shank co-contraction was 2.9 times greater in PPL (p<0.05) and 2.3 times greater in PHL (p<0.05) than in HSL. Thigh co-contraction was also 1.8 times greater in PPL than in HSL (p<0.05). The ankle plantar flexor muscle stiffness was statistically greater in PPL than in PHL and HSL (p<0.05). The efficiency was not statistically different between the three groups (p=0.155). In conclusion, the efficiency of work production by paretic and spastic lower limb muscles was normal ( congruent with 20%) despite significant neurological impairments. PMID:16274915

  10. Laboratory or field tests for evaluating firefighters' work capacity?

    PubMed

    Lindberg, Ann-Sofie; Oksa, Juha; Malm, Christer

    2014-01-01

    Muscle strength is important for firefighters work capacity. Laboratory tests used for measurements of muscle strength, however, are complicated, expensive and time consuming. The aims of the present study were to investigate correlations between physical capacity within commonly occurring and physically demanding firefighting work tasks and both laboratory and field tests in full time (N = 8) and part-time (N = 10) male firefighters and civilian men (N = 8) and women (N = 12), and also to give recommendations as to which field tests might be useful for evaluating firefighters' physical work capacity. Laboratory tests of isokinetic maximal (IM) and endurance (IE) muscle power and dynamic balance, field tests including maximal and endurance muscle performance, and simulated firefighting work tasks were performed. Correlations with work capacity were analyzed with Spearman's rank correlation coefficient (rs). The highest significant (p<0.01) correlations with laboratory and field tests were for Cutting: IE trunk extension (rs = 0.72) and maximal hand grip strength (rs = 0.67), for Stairs: IE shoulder flexion (rs = -0.81) and barbell shoulder press (rs = -0.77), for Pulling: IE shoulder extension (rs = -0.82) and bench press (rs = -0.85), for Demolition: IE knee extension (rs = 0.75) and bench press (rs = 0.83), for Rescue: IE shoulder flexion (rs = -0.83) and bench press (rs = -0.82), and for the Terrain work task: IE trunk flexion (rs = -0.58) and upright barbell row (rs = -0.70). In conclusion, field tests may be used instead of laboratory tests. Maximal hand grip strength, bench press, chin ups, dips, upright barbell row, standing broad jump, and barbell shoulder press were strongly correlated (rs≥0.7) with work capacity and are therefore recommended for evaluating firefighters work capacity. PMID:24614596

  11. Effects of stretching the scalene muscles on slow vital capacity.

    PubMed

    Lee, Juncheol; Hwang, Sehee; Han, Seungim; Han, Dongwook

    2016-06-01

    [Purpose] The purpose of this study was to examine whether stretching of the scalene muscles would improve slow vital capacity (SVC). [Subjects and Methods] The subjects of this study were 20 healthy female students to whom the study's methods and purpose were explained and their agreement for participation was obtained. The SVC was measured using spirometry (Pony FX, COSMED Inc., Italy). The intervention used was stretching of the scalene muscles. Stretching was carried out for 15 min, 10 times at per each portion of scalene muscles: the anterior, middle, and posterior parts. [Results] Expiratory vital capacity (EVC) and tidal volume (Vt) noticeably increased after stretching. However, there were no changes in any of the SVC items in the control group. [Conclusion] This study demonstrated that stretching of the scalene muscles can effectively improve SVC. In particular, we confirmed that stretching of the scalene muscles was effective in increasing EVC and Vt, which are items of SVC. PMID:27390425

  12. Effects of stretching the scalene muscles on slow vital capacity

    PubMed Central

    Lee, Juncheol; Hwang, Sehee; Han, Seungim; Han, Dongwook

    2016-01-01

    [Purpose] The purpose of this study was to examine whether stretching of the scalene muscles would improve slow vital capacity (SVC). [Subjects and Methods] The subjects of this study were 20 healthy female students to whom the study’s methods and purpose were explained and their agreement for participation was obtained. The SVC was measured using spirometry (Pony FX, COSMED Inc., Italy). The intervention used was stretching of the scalene muscles. Stretching was carried out for 15 min, 10 times at per each portion of scalene muscles: the anterior, middle, and posterior parts. [Results] Expiratory vital capacity (EVC) and tidal volume (Vt) noticeably increased after stretching. However, there were no changes in any of the SVC items in the control group. [Conclusion] This study demonstrated that stretching of the scalene muscles can effectively improve SVC. In particular, we confirmed that stretching of the scalene muscles was effective in increasing EVC and Vt, which are items of SVC. PMID:27390425

  13. Individual differences in working memory capacity and workload capacity

    PubMed Central

    Yu, Ju-Chi; Chang, Ting-Yun; Yang, Cheng-Ta

    2014-01-01

    We investigated the relationship between working memory capacity (WMC) and workload capacity (WLC). Each participant performed an operation span (OSPAN) task to measure his/her WMC and three redundant-target detection tasks to measure his/her WLC. WLC was computed non-parametrically (Experiments 1 and 2) and parametrically (Experiment 2). Both levels of analyses showed that participants high in WMC had larger WLC than those low in WMC only when redundant information came from visual and auditory modalities, suggesting that high-WMC participants had superior processing capacity in dealing with redundant visual and auditory information. This difference was eliminated when multiple processes required processing for only a single working memory subsystem in a color-shape detection task and a double-dot detection task. These results highlighted the role of executive control in integrating and binding information from the two working memory subsystems for perceptual decision making. PMID:25566143

  14. Working and Net Available Shell Storage Capacity

    EIA Publications

    2016-01-01

    Working and Net Available Shell Storage Capacity is the U.S. Energy Information Administration’s (EIA) report containing storage capacity data for crude oil, petroleum products, and selected biofuels. The report includes tables detailing working and net available shell storage capacity by type of facility, product, and Petroleum Administration for Defense District (PAD District). Net available shell storage capacity is broken down further to show the percent for exclusive use by facility operators and the percent leased to others. Crude oil storage capacity data are also provided for Cushing, Oklahoma, an important crude oil market center. Data are released twice each year near the end of May (data for March 31) and near the end of November (data for September 30).

  15. Laboratory or Field Tests for Evaluating Firefighters' Work Capacity?

    PubMed Central

    Lindberg, Ann-Sofie; Oksa, Juha; Malm, Christer

    2014-01-01

    Muscle strength is important for firefighters work capacity. Laboratory tests used for measurements of muscle strength, however, are complicated, expensive and time consuming. The aims of the present study were to investigate correlations between physical capacity within commonly occurring and physically demanding firefighting work tasks and both laboratory and field tests in full time (N = 8) and part-time (N = 10) male firefighters and civilian men (N = 8) and women (N = 12), and also to give recommendations as to which field tests might be useful for evaluating firefighters' physical work capacity. Laboratory tests of isokinetic maximal (IM) and endurance (IE) muscle power and dynamic balance, field tests including maximal and endurance muscle performance, and simulated firefighting work tasks were performed. Correlations with work capacity were analyzed with Spearman's rank correlation coefficient (rs). The highest significant (p<0.01) correlations with laboratory and field tests were for Cutting: IE trunk extension (rs = 0.72) and maximal hand grip strength (rs = 0.67), for Stairs: IE shoulder flexion (rs = −0.81) and barbell shoulder press (rs = −0.77), for Pulling: IE shoulder extension (rs = −0.82) and bench press (rs = −0.85), for Demolition: IE knee extension (rs = 0.75) and bench press (rs = 0.83), for Rescue: IE shoulder flexion (rs = −0.83) and bench press (rs = −0.82), and for the Terrain work task: IE trunk flexion (rs = −0.58) and upright barbell row (rs = −0.70). In conclusion, field tests may be used instead of laboratory tests. Maximal hand grip strength, bench press, chin ups, dips, upright barbell row, standing broad jump, and barbell shoulder press were strongly correlated (rs≥0.7) with work capacity and are therefore recommended for evaluating firefighters work capacity. PMID:24614596

  16. Satellite cells from dystrophic muscle retain regenerative capacity.

    PubMed

    Boldrin, Luisa; Zammit, Peter S; Morgan, Jennifer E

    2015-01-01

    Duchenne muscular dystrophy is an inherited disorder that is characterized by progressive skeletal muscle weakness and wasting, with a failure of muscle maintenance/repair mediated by satellite cells (muscle stem cells). The function of skeletal muscle stem cells resident in dystrophic muscle may be perturbed by being in an increasing pathogenic environment, coupled with constant demands for repairing muscle. To investigate the contribution of satellite cell exhaustion to this process, we tested the functionality of satellite cells isolated from the mdx mouse model of Duchenne muscular dystrophy. We found that satellite cells derived from young mdx mice contributed efficiently to muscle regeneration within our in vivo mouse model. To then test the effects of long-term residence in a dystrophic environment, satellite cells were isolated from aged mdx muscle. Surprisingly, they were as functional as those derived from young or aged wild type donors. Removing satellite cells from a dystrophic milieu reveals that their regenerative capacity remains both intact and similar to satellite cells derived from healthy muscle, indicating that the host environment is critical for controlling satellite cell function. PMID:25460248

  17. When Higher Working Memory Capacity Hinders Insight

    ERIC Educational Resources Information Center

    DeCaro, Marci S.; Van Stockum, Charles A., Jr.; Wieth, Mareike B.

    2016-01-01

    Higher working memory capacity (WMC) improves performance on a range of cognitive and academic tasks. However, a greater ability to control attention sometimes leads individuals with higher WMC to persist in using complex, attention-demanding approaches that are suboptimal for a given task. We examined whether higher WMC would hinder insight…

  18. Working Memory Capacity and Resistance to Interference

    ERIC Educational Resources Information Center

    Oberauer, Klaus; Lange, Elke; Engle, Randall W.

    2004-01-01

    Single-task and dual-task versions of verbal and spatial serial order memory tasks were administered to 120 students tested for working memory capacity with four previously validated measures. In the dual-task versions, similarity between the memory material and the material of the secondary processing task was varied. With verbal material, three…

  19. Working Memory Capacity as a Dynamic Process

    PubMed Central

    Simmering, Vanessa R.; Perone, Sammy

    2013-01-01

    A well-known characteristic of working memory (WM) is its limited capacity. The source of such limitations, however, is a continued point of debate. Developmental research is positioned to address this debate by jointly identifying the source(s) of limitations and the mechanism(s) underlying capacity increases. Here we provide a cross-domain survey of studies and theories of WM capacity development, which reveals a complex picture: dozens of studies from 50 papers show nearly universal increases in capacity estimates with age, but marked variation across studies, tasks, and domains. We argue that the full pattern of performance cannot be captured through traditional approaches emphasizing single causes, or even multiple separable causes, underlying capacity development. Rather, we consider WM capacity as a dynamic process that emerges from a unified cognitive system flexibly adapting to the context and demands of each task. We conclude by enumerating specific challenges for researchers and theorists that will need to be met in order to move our understanding forward. PMID:23335902

  20. Skeletal Muscle Oxidative Capacity in Patients with Cystic Fibrosis

    PubMed Central

    Erickson, Melissa L.; Seigler, Nichole; McKie, Kathleen T.; McCully, Kevin K.; Harris, Ryan A.

    2016-01-01

    Introduction Exercise intolerance predicts mortality in patients with cystic fibrosis (CF); however, the mechanisms have yet to be fully elucidated. Using near infrared spectroscopy (NIRS), this study compared skeletal muscle oxidative capacity in patients with CF to healthy controls. Methods Thirteen patients and 16 demographically-matched controls participated in this study. NIRS was utilized to measure the recovery rate of oxygen consumption (musVO2max) of the vastus lateralis muscle after 15 s of electrical stimulation (4 Hz) and subsequent repeated transient arterial occlusions. Results musVO2max was reduced in patients with CF (1.82 ± 0.4 min−1) compared to controls (2.13 ± 0.5 min−1, p = 0.04). A significant inverse relationship between age and musVO2max was observed in patients (r = −0.676, p = 0.011), but not controls (r = −0.291, p = 0.274). Discussion Patients with CF exhibit a reduction in skeletal muscle oxidative capacity compared to controls. It appears as the reduced skeletal muscle oxidative capacity is accelerated by age and could likely contribute to exercise intolerance in patients with CF. PMID:25758606

  1. Physical Fitness and Mitochondrial Respiratory Capacity in Horse Skeletal Muscle

    PubMed Central

    Lemieux, Hélène; Mouithys-Mickalad, Ange; Serteyn, Didier

    2012-01-01

    Background Within the animal kingdom, horses are among the most powerful aerobic athletic mammals. Determination of muscle respiratory capacity and control improves our knowledge of mitochondrial physiology in horses and high aerobic performance in general. Methodology/Principal Findings We applied high-resolution respirometry and multiple substrate-uncoupler-inhibitor titration protocols to study mitochondrial physiology in small (1.0–2.5 mg) permeabilized muscle fibres sampled from triceps brachii of healthy horses. Oxidative phosphorylation (OXPHOS) capacity (pmol O2•s−1•mg−1 wet weight) with combined Complex I and II (CI+II) substrate supply (malate+glutamate+succinate) increased from 77±18 in overweight horses to 103±18, 122±15, and 129±12 in untrained, trained and competitive horses (N = 3, 8, 16, and 5, respectively). Similar to human muscle mitochondria, equine OXPHOS capacity was limited by the phosphorylation system to 0.85±0.10 (N = 32) of electron transfer capacity, independent of fitness level. In 15 trained horses, OXPHOS capacity increased from 119±12 to 134±37 when pyruvate was included in the CI+II substrate cocktail. Relative to this maximum OXPHOS capacity, Complex I (CI)-linked OXPHOS capacities were only 50% with glutamate+malate, 64% with pyruvate+malate, and 68% with pyruvate+malate+glutamate, and ∼78% with CII-linked succinate+rotenone. OXPHOS capacity with glutamate+malate increased with fitness relative to CI+II-supported ETS capacity from a flux control ratio of 0.38 to 0.40, 0.41 and 0.46 in overweight to competitive horses, whereas the CII/CI+II substrate control ratio remained constant at 0.70. Therefore, the apparent deficit of the CI- over CII-linked pathway capacity was reduced with physical fitness. Conclusions/Significance The scope of mitochondrial density-dependent OXPHOS capacity and the density-independent (qualitative) increase of CI-linked respiratory capacity with increased fitness open up new

  2. Intracellular Acidosis Enhances the Excitability of Working Muscle

    NASA Astrophysics Data System (ADS)

    Pedersen, Thomas H.; Nielsen, Ole B.; Lamb, Graham D.; Stephenson, D. George

    2004-08-01

    Intracellular acidification of skeletal muscles is commonly thought to contribute to muscle fatigue. However, intracellular acidosis also acts to preserve muscle excitability when muscles become depolarized, which occurs with working muscles. Here, we show that this process may be mediated by decreased chloride permeability, which enables action potentials to still be propagated along the internal network of tubules in a muscle fiber (the T system) despite muscle depolarization. These results implicate chloride ion channels in muscle function and emphasize that intracellular acidosis of muscle has protective effects during muscle fatigue.

  3. Working memory capacity in Generalized Social Phobia

    PubMed Central

    Amir, Nader; Bomyea, Jessica

    2011-01-01

    Research suggests that understanding complex social cues depends on the availability of cognitive resources (e.g., Phillips, Channon, Tunstall, Hedenstrom, & Lyons, 2008). In spite of evidence suggesting that executive control functioning may impact anxiety (e.g., Eysenck, Derakshan, Santos, & Calvo, 2007), relatively few studies have examined working memory in individuals with Generalized Social Phobia (GSP). Moreover, few studies have examined the role of threat-relevant content in working memory performance in clinically anxious populations. To this end, the present study assessed working memory capacity (WMC) in individuals with Generalized Social Phobia and non-anxious controls using an Operation Span task using threat relevant and neutral stimuli. Results revealed that non-anxious individuals demonstrated better WMC than individuals with GSP for neutral words, but not for social threat words. Individuals with GSP demonstrated better WMC performance for threat words relative to neutral words. These results suggest that individuals with GSP may have relatively enhanced working memory performance for salient, socially-relevant information. This enhanced working memory capacity for threat relevant information may be the result of practice with this information in GSP. PMID:21381805

  4. Working memory capacity in generalized social phobia.

    PubMed

    Amir, Nader; Bomyea, Jessica

    2011-05-01

    Research suggests that understanding complex social cues depends on the availability of cognitive resources (e.g., Phillips, Channon, Tunstall, Hedenstrom, & Lyons, 2008). In spite of evidence suggesting that executive control functioning may impact anxiety (e.g., Eysenck, Derakshan, Santos, & Calvo, 2007), relatively few studies have examined working memory in individuals with generalized social phobia. Moreover, few studies have examined the role of threat-relevant content in working memory performance in clinically anxious populations. To this end, the present study assessed working memory capacity (WMC) in individuals with generalized social phobia and nonanxious controls using an operation span task with threat-relevant and neutral stimuli. Results revealed that nonanxious individuals demonstrated better WMC than individuals with generalized social phobia for neutral words but not for social threat words. Individuals with generalized social phobia demonstrated better WMC performance for threat words relative to neutral words. These results suggest that individuals with generalized social phobia may have relatively enhanced working memory performance for salient, socially relevant information. This enhanced working memory capacity for threat-relevant information may be the result of practice with this information in generalized social phobia. PMID:21381805

  5. Enzymatic capacities of skeletal muscle - Effects of different types of training

    NASA Technical Reports Server (NTRS)

    Booth, F. W.; Hugman, G. R.

    1981-01-01

    Long-term adaptation mechanisms to maintain homeostasis at increased levels of exertion such as those caused by regular exercise are described. Mitochondrial changes have been found to be a result of endurance exercises, while mitochondrial responses to other types of exercise are small. Further discussion is devoted to long-term changes in glucose transport, hexokinase, phosphofructokinase, pyruvate kinase, and the increased sensitivity of an endurance trained muscle to insulin. Less lactate has been found to be produced by the skeletal muscles at the same work rate after adaptation to endurance exercise training, and the capacity for the flux of the two-carbon acetyl chain through the citric acid cycle increases in skeletal muscles in response to endurance training. Finally, endurance training is noted to result in glycogen sparing and an increase in the capacity to utilize fatty acids.

  6. Work capacity of permanent residents of high altitude.

    PubMed

    Marconi, Claudio; Marzorati, Mauro; Cerretelli, Paolo

    2006-01-01

    Tibetan and Andean natives at altitude have allegedly a greater work capacity and stand fatigue better than acclimatized lowlanders. The principal aim of the present review is to establish whether convincing experimental evidence supports this belief and, should this be the case, to analyze the possible underlying mechanisms. The superior work capacity of high altitude natives is not based on differences in maximum aerobic power (V(O2 peak)), mL kg(-1)min(-1)). In fact, average V (O2 peak) of both Tibetan and Andean natives at altitude is only slightly, although not significantly, higher than that of Asian or Caucasian lowlanders resident for more than 1 yr between 3400 and 4700 m (Tibetans, n = 152, vs. Chinese Hans, n = 116: 42.4 +/- 3.4 vs. 39.2 +/- 2.6 mL kg(-1)min(-1), mean +/- SE; Andeans, n = 116, vs. Caucasians, n = 70: 47.1 +/- 1.7 vs. 41.6 +/- 1.2 mL kg(-1)min(-1)). However, compared to acclimatized lowlanders, Tibetans appear to be characterized by a better economy of cycling, walking, and running on a treadmill. This is possibly due to metabolic adaptations, such as increased muscle myoglobin content and antioxidant defense. All together, the latter changes may enhance the efficiency of the muscle oxidative metabolic machinery, thereby supporting a better prolonged submaximal performance capacity compared to lowlanders, despite equal V(O2 peak). With regard to Andeans, data on exercise efficiency is scanty and controversial and, at present, no conclusion can be drawn as to the origin of their superior performance. PMID:16764524

  7. When higher working memory capacity hinders insight.

    PubMed

    DeCaro, Marci S; Van Stockum, Charles A; Wieth, Mareike B

    2016-01-01

    Higher working memory capacity (WMC) improves performance on a range of cognitive and academic tasks. However, a greater ability to control attention sometimes leads individuals with higher WMC to persist in using complex, attention-demanding approaches that are suboptimal for a given task. We examined whether higher WMC would hinder insight problem solving, which is thought to rely on associative processes that operate largely outside of close attentional control. In addition, we examined whether characteristics of the insight problems influence whether this negative relationship will be revealed. In Experiment 1, participants completed matchstick arithmetic problems, which require a similar initial problem representation for all problems. Higher WMC was associated with less accurate insight problem solving. In Experiment 2, participants completed insight word problems, which require substantially different representations for each problem. Higher WMC was again negatively associated with insight, but only after statistically controlling for shared variance between insight and incremental problem-solving accuracy. These findings suggest that WMC may benefit performance on fundamental processes common to both incremental and insight problem solving (e.g., initial problem representation), but hinder performance on the processes that are unique to insight (e.g., solution and restructuring). By considering the WMC of the individual, and the nature of the insight task, we may better understand the process of insight and how to best support it. (PsycINFO Database Record PMID:26120772

  8. Work partitioning of transversally loaded muscle: experimentation and simulation.

    PubMed

    Siebert, Tobias; Till, Olaf; Blickhan, Reinhard

    2014-01-01

    Skeletal muscles are surrounded by other muscles, connective tissue and bones, which may transfer transversal forces to the muscle belly. Simple Hill-type muscle models do not consider transversal forces. Thus, the aim of this study was to examine and model the influence of transversal muscle loading on contraction dynamics, e.g. on the rate of force development and on the maximum isometric muscle force (Fim). Isometric experiments with and without transversal muscle loading were conducted on rat muscles. The muscles were loaded (1.3 N cm⁻²) by a custom-made plunger which was able to move in transversal direction. Then the muscle was fully stimulated, the isometric force was measured at the distal tendon and the movement of the plunger was captured with a high-speed camera. The interaction between the muscle and the transversal load was modelled based on energy balance between the (1) work done by the contractile component (CC) and (2) the work done to lift the load, to stretch the series elastic structures and to deform the muscle. Compared with the unloaded contraction, the force rate was reduced by about 25% and Fim was reduced by 5% both in the experiment and in the simulation. The reduction in Fim resulted from using part of the work done by the CC to lift the load and deform the muscle. The response of the muscle to transversal loading opens a window into the interdependence of contractile and deformation work, which can be used to specify and validate 3D muscle models. PMID:22515574

  9. Operational calm and the optimum regulation of human working capacity

    NASA Technical Reports Server (NTRS)

    Ilin, Y. P.

    1975-01-01

    Muscle hardness measurements in a squeezing dynamometer test are interpreted for expressions of adjustment effects of the central nervous system in rapid response to a starting signal. It is shown that preliminary muscle tension leads to the transmission of inhibiting proprioceptive impulses to the nervous system centers and that the degree of pre-working changes depends on the individual's typological personality characteristics. Concentration of attention during the pre-working adjustment is considered the primary emotional factor that controls sensorimotor performance.

  10. [Work capacity perceived by nurses: descriptive study].

    PubMed

    Tomietto, Marco; Zanini, Antonietta; Sgrazzutti, Sasha; Palese, Alvisa

    2011-01-01

    Perceived work ability is the worker perception of his/her job performances. There are many factors involved in this perception: individual characteristics (such as health status, motivation, and attitudes), job characteristics (such as technological resources, physical and mental demands) and working climate (such as job organization and leadership styles). The promotion of a good work ability could decrease the premature loss of workers and could help them in facing job demands and stress. In the health care settings the risk to perceive a low work ability could be higher due to nurses' shortage. The main aim of this pilot study was to measure the perceived work ability among nurses in order to find the work ability predictors. 78 nurses were recruited and had filled the Work Ability Index (WAI). The main work ability predictors found were: age over 45 years (OR=4,56; IC 95% 1,14 to 19,14), working years over 15 (OR=3,18; IC 95% 1,09 to 9,45) and more than 3 diseases (OR=25,00; IC95% 3,17 to 531,90). These results give useful information to health care managers in order to improve human resources management strategies and to find solutions about nurses' shortage and aging workforce. PMID:22452097

  11. Enhancing Research Capacity in Gerontological Social Work

    ERIC Educational Resources Information Center

    Mehrotra, Chandra M.; Townsend, Aloen; Berkman, Barbara

    2009-01-01

    There is an untapped potential of social work faculty to conduct aging research aimed at enhancing the well-being of older adults. To better exploit this resource, we have designed, implemented, and evaluated a postgraduate training program in aging research. The goal of the program is to build and sustain a community of social work faculty…

  12. Perm1 enhances mitochondrial biogenesis, oxidative capacity, and fatigue resistance in adult skeletal muscle.

    PubMed

    Cho, Yoshitake; Hazen, Bethany C; Gandra, Paulo G; Ward, Samuel R; Schenk, Simon; Russell, Aaron P; Kralli, Anastasia

    2016-02-01

    Skeletal muscle mitochondrial content and oxidative capacity are important determinants of muscle function and whole-body health. Mitochondrial content and function are enhanced by endurance exercise and impaired in states or diseases where muscle function is compromised, such as myopathies, muscular dystrophies, neuromuscular diseases, and age-related muscle atrophy. Hence, elucidating the mechanisms that control muscle mitochondrial content and oxidative function can provide new insights into states and diseases that affect muscle health. In past studies, we identified Perm1 (PPARGC1- and ESRR-induced regulator, muscle 1) as a gene induced by endurance exercise in skeletal muscle, and regulating mitochondrial oxidative function in cultured myotubes. The capacity of Perm1 to regulate muscle mitochondrial content and function in vivo is not yet known. In this study, we use adeno-associated viral (AAV) vectors to increase Perm1 expression in skeletal muscles of 4-wk-old mice. Compared to control vector, AAV1-Perm1 leads to significant increases in mitochondrial content and oxidative capacity (by 40-80%). Moreover, AAV1-Perm1-transduced muscles show increased capillary density and resistance to fatigue (by 33 and 31%, respectively), without prominent changes in fiber-type composition. These findings suggest that Perm1 selectively regulates mitochondrial biogenesis and oxidative function, and implicate Perm1 in muscle adaptations that also occur in response to endurance exercise. PMID:26481306

  13. Regenerative capacity of old muscle stem cells declines without significant accumulation of DNA damage.

    PubMed

    Cousin, Wendy; Ho, Michelle Liane; Desai, Rajiv; Tham, Andrea; Chen, Robert Yuzen; Kung, Sunny; Elabd, Christian; Conboy, Irina M

    2013-01-01

    The performance of adult stem cells is crucial for tissue homeostasis but their regenerative capacity declines with age, leading to failure of multiple organs. In skeletal muscle this failure is manifested by the loss of functional tissue, the accumulation of fibrosis, and reduced satellite cell-mediated myogenesis in response to injury. While recent studies have shown that changes in the composition of the satellite cell niche are at least in part responsible for the impaired function observed with aging, little is known about the effects of aging on the intrinsic properties of satellite cells. For instance, their ability to repair DNA damage and the effects of a potential accumulation of DNA double strand breaks (DSBs) on their regenerative performance remain unclear. This work demonstrates that old muscle stem cells display no significant accumulation of DNA DSBs when compared to those of young, as assayed after cell isolation and in tissue sections, either in uninjured muscle or at multiple time points after injury. Additionally, there is no significant difference in the expression of DNA DSB repair proteins or globally assayed DNA damage response genes, suggesting that not only DNA DSBs, but also other types of DNA damage, do not significantly mark aged muscle stem cells. Satellite cells from DNA DSB-repair-deficient SCID mice do have an unsurprisingly higher level of innate DNA DSBs and a weakened recovery from gamma-radiation-induced DNA damage. Interestingly, they are as myogenic in vitro and in vivo as satellite cells from young wild type mice, suggesting that the inefficiency in DNA DSB repair does not directly correlate with the ability to regenerate muscle after injury. Overall, our findings suggest that a DNA DSB-repair deficiency is unlikely to be a key factor in the decline in muscle regeneration observed upon aging. PMID:23704914

  14. Locomotor performance and muscle metabolic capacities: impact of temperature and energetic status.

    PubMed

    Guderley, Helga

    2004-11-01

    In aquatic ectotherms, muscle metabolic capacities are strongly influenced by exogenous factors, principally temperature and food availability. Seasonal changes in temperature lead many organisms to modify their metabolic machinery so as to maintain capacity even in "slower" cold habitats. Modifications of mitochondrial capacities are central in this response. The increases in protein-specific oxidative capacities of mitochondria during cold acclimation of temperate fishes do not occur during the evolutionary adaptation to cold in Antarctic species. Instead, Antarctic fishes tend to increase the proportion of fibre volume devoted to mitochondria, perhaps to facilitate intracellular distribution of oxygen and metabolites. Variation in energetic status can drastically modify muscle metabolic status, with glycolytic muscle changing more than oxidative muscle. This in turn impacts swimming performance. A decrease in the condition of cod leads endurance at speeds above Ucrit to drop by 70%. Sprint swimming is less affected, perhaps as it does not exhaust glycolytic muscle. We used interindividual variation in muscle metabolic capacities to identify correlates of swimming performance in stickleback and cod. Activities of cytochrome c oxidase in glycolytic muscle are a correlate of sprint swimming in stickleback (Gasterosteus aculeatus) and cod (Gadus morhua), whereas lactate dehydrogenase activities in glycolytic muscle are a correlate of cod endurance swimming. In scallops, gonadal maturation leads to virtually complete mobilisation of glycogen from muscle. This does not reduce the capacity of the scallops, Chlamys islandica and Euvola ziczac, to mount escape responses, but significantly slows their recuperation from exhaustive exercise. Muscle metabolic capacities fall in parallel with glycogen mobilisation. In the compromise between muscles' dual roles as a motor and a macromolecular reserve, a significant loss in locomotory ability occurs during gametogenesis and

  15. Condition, prolonged swimming performance and muscle metabolic capacities of cod Gadus morhua.

    PubMed

    Martínez, M; Guderley, H; Dutil, J-D; Winger, P D; He, P; Walsh, S J

    2003-02-01

    This study evaluated the link between swimming endurance and condition of Atlantic cod Gadus morhua that had been fed or starved during the 16 weeks preceding the tests, and assessed whether muscle metabolic capacities explain such links. The condition factor [(somatic mass x fork length(-3))x100] of starved cod was 0.54+/-0.1 whereas that of fed cod was 0.81+/-0.1. In white and red muscle, we measured four glycolytic enzymes: phosphofructokinase (PFK), pyruvate kinase (PK), creatine kinase (CK) and lactate dehydrogenase (LDH), two mitochondrial enzymes: cytochrome c oxidase (CCO) and citrate synthase (CS), a biosynthetic enzyme, nucleoside diphosphate kinase (NDPK), glycogen and protein levels and water content. Muscle samples were taken at three positions along the length of the fish; starvation affected the metabolic capacities of white muscle more than those of red muscle. The levels of glycolytic enzymes and glycogen changed more in white than red muscle during starvation. Both in fed and starved cod, muscle metabolic capacities varied with position along the fish; starvation reduced this longitudinal variation more in white than red muscle. In white muscle of fed cod, the glycolytic enzyme levels increased from head to tail, while in starved cod this longitudinal variation disappeared. In red muscle mitochondrial enzyme levels were highest in the caudal sample, but fewer differences were found for glycolytic enzymes. Swimming endurance was markedly affected by fish condition, with starved fish swimming only 30% of the time (and distance) of fed fish. This endurance was closely linked with the number of burst-coast movements during the test and the activity of CCO and LDH in white muscle. The number of burst-coast movements was significantly linked with condition factor and PFK activity in caudal red muscle and gill arch mass. Our data indicated that cod use both glycolytic and oxidative capacities to support endurance swimming. Furthermore, swimming endurance

  16. [Work capacity in patients on hemodialysis].

    PubMed

    Orlić, Lidija; Matić-Glazar, Durdica; Sladoje Martinović, Branka; Vlahović, Ana

    2004-01-01

    beginning of hemodialysis and retirement was: less than 1 year work 13 (36.1%) patients, 1-2 year work 6 (16.7%), three year work 2 patients, more than 8 year work 2 patients, and 10 year work only 3 patients, for 14, 18 and 26 years each. Two patients lost their job for employer bankruptcy. The judgment of patients regarding their occupational ability was as follows: out of 161 patients, 23 (14.3%) felt fit for work, 12 on full-time and 11 on part-time basis. Occupationally incapable were 46.6% of patients, and 63 felt unable to take care of another person. Some kind of additional activity, like working in garden or taking care of children was reported by 26 patients. The aforementioned results showed that 22.4% of the patients were occupationally active at the time of starting hemodialysis. Many patients were retired after hemodialysis had started. Only 6.2% of hemodialysis patients were occupationally active although 14.3% felt occupationally capable. The main reasons for such a low level of employment were advanced age, diminished physical activity due to the disease, and difficulties associated with the socioeconomic situation in the country. PMID:15125397

  17. Working capacity of deaf and visually and mentally handicapped children*

    PubMed Central

    Cumming, G. R.; Goulding, D.; Baggley, G.

    1971-01-01

    Using bicycle ergometers, physical working capacity was determined in 61 deaf, 22 visually handicapped, and 67 mentally retarded children 8 to 17 years of age. Compared to the normal population, the working capacities per kilogram body weight of the deaf children, particularly the girls, were superior to the other groups and to the normal population. The visually handicapped had lower working capacities, while those of the retarded children were similar to the normals. The work efficiency was similar in both groups. For the boys and younger girls, the maximum oxygen uptakes per kilogram body weight were similar in the deaf and visually handicapped, results that were contrary to the working capacity studies. The difference could be explained by postulating that the deaf children did not work to maximal values though lactic acid and respiratory quotient data suggested that they did. The maximum heart rates of the deaf children were lower than the visually handicapped. PMID:5565460

  18. The relationship between sustained inattentional blindness and working memory capacity.

    PubMed

    Beanland, Vanessa; Chan, Esther Hiu Chung

    2016-04-01

    Inattentional blindness, whereby observers fail to detect unexpected stimuli, has been robustly demonstrated in a range of situations. Originally research focused primarily on how stimulus characteristics and task demands affect inattentional blindness, but increasingly studies are exploring the influence of observer characteristics on the detection of unexpected stimuli. It has been proposed that individual differences in working memory capacity predict inattentional blindness, on the assumption that higher working memory capacity confers greater attentional capacity for processing unexpected stimuli. Unfortunately, empirical investigations of the association between inattentional blindness and working memory capacity have produced conflicting findings. To help clarify this relationship, we examined the relationship between inattentional blindness and working memory capacity in two samples (Ns = 195, 147) of young adults. We used three common variants of sustained inattentional blindness tasks, systematically manipulating the salience of the unexpected stimulus and primary task practice. Working memory capacity, measured by automated operation span (both Experiments 1 & 2) and N-back (Experiment 1 only) tasks, did not predict detection of the unexpected stimulus in any of the inattentional blindness tasks tested. Together with previous research, this undermines claims that there is a robust relationship between inattentional blindness and working memory capacity. Rather, it appears that any relationship between inattentional blindness and working memory is either too small to have practical significance or is moderated by other factors and consequently varies with attributes such as the sample characteristics within a given study. PMID:26754810

  19. Estrogen-related receptor gamma is a key regulator of muscle mitochondrial activity and oxidative capacity.

    PubMed

    Rangwala, Shamina M; Wang, Xiaomei; Calvo, Jennifer A; Lindsley, Loren; Zhang, Yunyu; Deyneko, Galina; Beaulieu, Valerie; Gao, Jiaping; Turner, Gordon; Markovits, Judit

    2010-07-16

    Estrogen-related receptor gamma (ERRgamma) regulates the perinatal switch to oxidative metabolism in the myocardium. We wanted to understand the significance of induction of ERRgamma expression in skeletal muscle by exercise. Muscle-specific VP16ERRgamma transgenic mice demonstrated an increase in exercise capacity, mitochondrial enzyme activity, and enlarged mitochondria despite lower muscle weights. Furthermore, peak oxidative capacity was higher in the transgenics as compared with control littermates. In contrast, mice lacking one copy of ERRgamma exhibited decreased exercise capacity and muscle mitochondrial function. Interestingly, we observed that increased ERRgamma in muscle generates a gene expression profile that closely overlays that of red oxidative fiber-type muscle. We further demonstrated that a small molecule agonist of ERRbeta/gamma can increase mitochondrial function in mouse myotubes. Our data indicate that ERRgamma plays an important role in causing a shift toward slow twitch muscle type and, concomitantly, a greater capacity for endurance exercise. Thus, the activation of this nuclear receptor provides a potential node for therapeutic intervention for diseases such as obesity, which is associated with reduced oxidative metabolism and a lower type I fiber content in skeletal muscle. PMID:20418374

  20. Estrogen-related Receptor γ Is a Key Regulator of Muscle Mitochondrial Activity and Oxidative Capacity

    PubMed Central

    Rangwala, Shamina M.; Wang, Xiaomei; Calvo, Jennifer A.; Lindsley, Loren; Zhang, Yunyu; Deyneko, Galina; Beaulieu, Valerie; Gao, Jiaping; Turner, Gordon; Markovits, Judit

    2010-01-01

    Estrogen-related receptor γ (ERRγ) regulates the perinatal switch to oxidative metabolism in the myocardium. We wanted to understand the significance of induction of ERRγ expression in skeletal muscle by exercise. Muscle-specific VP16ERRγ transgenic mice demonstrated an increase in exercise capacity, mitochondrial enzyme activity, and enlarged mitochondria despite lower muscle weights. Furthermore, peak oxidative capacity was higher in the transgenics as compared with control littermates. In contrast, mice lacking one copy of ERRγ exhibited decreased exercise capacity and muscle mitochondrial function. Interestingly, we observed that increased ERRγ in muscle generates a gene expression profile that closely overlays that of red oxidative fiber-type muscle. We further demonstrated that a small molecule agonist of ERRβ/γ can increase mitochondrial function in mouse myotubes. Our data indicate that ERRγ plays an important role in causing a shift toward slow twitch muscle type and, concomitantly, a greater capacity for endurance exercise. Thus, the activation of this nuclear receptor provides a potential node for therapeutic intervention for diseases such as obesity, which is associated with reduced oxidative metabolism and a lower type I fiber content in skeletal muscle. PMID:20418374

  1. Knowledge Cannot Explain the Developmental Growth of Working Memory Capacity

    ERIC Educational Resources Information Center

    Cowan, Nelson; Ricker, Timothy J.; Clark, Katherine M.; Hinrichs, Garrett A.; Glass, Bret A.

    2015-01-01

    According to some views of cognitive growth, the development of working memory capacity can account for increases in the complexity of cognition. It has been difficult to ascertain, though, that there actually is developmental growth in capacity that cannot be attributed to other developing factors. Here we assess the role of item familiarity. We…

  2. Inheritance of human skeletal muscle and anaerobic capacity adaptation to high-intensity intermittent training.

    PubMed

    Simoneau, J A; Lortie, G; Boulay, M R; Marcotte, M; Thibault, M C; Bouchard, C

    1986-06-01

    The role of heredity in the response of maximal anaerobic capacities and skeletal muscle histochemical and biochemical characteristics to a 15-week cycle ergometer training program involving both continuous and interval work patterns was investigated in 14 pairs of monozygotic twins. The training program consisted mainly of series of ergocycle supramaximal exercises lasting from 15 s to 90 s and performed 4 and 5 times a week. The subjects were submitted to 10 s and 90 s all-out ergocycle tests to estimate maximal anaerobic alactacid (AAC) and lactacid (ALC) capacities, respectively. Muscle fiber types and creatine kinase (CK), hexokinase (HK), phosphofructokinase (PFK), lactate dehydrogenase (LDH), malate dehydrogenase (MDH), 3-hydroxyacyl CoA dehydrogenase (HADH), and oxoglutarate dehydrogenase (OGDH) activities were determined in a biopsy from the vastus lateralis. Training increased AAC, ALC, fiber type I proportion, MDH, HADH, and OGDH (P less than 0.05) and decreased fiber type IIb proportion and the PFK/OGDH ratio. No significant change was observed for CK, HK, PFK, and LDH. Large interindividual differences in the response to training were observed for all variables. However, intraclass correlations indicated that the extent of the response of ALC and CK, HK, LDH, MDH, and OGDH activities and of the PFK/OGDH activity ratio to training were significantly similar within pairs of twins. Although the role of heredity appeared absent for the changes in fiber type proportions and in anaerobic alactacid capacity, the present results suggest that the response of anaerobic lactacid capacity and most enzyme activities to high-intensity intermittent training is significantly determined by the genotype. PMID:3733313

  3. Relation of systemic and local muscle exercise capacity to skeletal muscle characteristics in men with congestive heart failure

    NASA Technical Reports Server (NTRS)

    Massie, B. M.; Simonini, A.; Sahgal, P.; Wells, L.; Dudley, G. A.

    1996-01-01

    OBJECTIVES. The present study was undertaken to further characterize changes in skeletal muscle morphology and histochemistry in congestive heart failure and to determine the relation of these changes to abnormalities of systemic and local muscle exercise capacity. BACKGROUND. Abnormalities of skeletal muscle appear to play a role in the limitation of exercise capacity in congestive heart failure, but information on the changes in muscle morphology and biochemistry and their relation to alterations in muscle function is limited. METHODS. Eighteen men with predominantly mild to moderate congestive heart failure (mean +/- SEM New York Heart Association functional class 2.6 +/- 0.2, ejection fraction 24 +/- 2%) and eight age- and gender-matched sedentary control subjects underwent measurements of peak systemic oxygen consumption (VO2) during cycle ergometry, resistance to fatigue of the quadriceps femoris muscle group and biopsy of the vastus lateralis muscle. RESULTS. Peak VO2 and resistance to fatigue were lower in the patients with heart failure than in control subjects (15.7 +/- 1.2 vs. 25.1 +/- 1.5 ml/min-kg and 63 +/- 2% vs. 85 +/- 3%, respectively, both p < 0.001). Patients had a lower proportion of slow twitch, type I fibers than did control subjects (36 +/- 3% vs. 46 +/- 5%, p = 0.048) and a higher proportion of fast twitch, type IIab fibers (18 +/- 3% vs. 7 +/- 2%, p = 0.004). Fiber cross-sectional area was smaller, and single-fiber succinate dehydrogenase activity, a mitochondrial oxidative marker, was lower in patients (both p < or = 0.034). Likewise, the ratio of average fast twitch to slow twitch fiber cross-sectional area was lower in patients (0.780 +/- 0.06 vs. 1.05 +/- 0.08, p = 0.019). Peak VO2 was strongly related to integrated succinate dehydrogenase activity in patients (r = 0.896, p = 0.001). Peak VO2, resistance to fatigue and strength also correlated significantly with several measures of fiber size, especially of fast twitch fibers, in

  4. Regulation of skeletal muscle oxidative capacity and muscle mass by SIRT3

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We have previously reported that the expression of mitochondrial deacetylase SIRT3 is high in the slow oxidative muscle and that the expression of muscle SIRT3 level is increased by dietary restriction or exercise training. To explore the function of SIRT3 in skeletal muscle, we report here the esta...

  5. Fetal skeletal muscle progenitors have regenerative capacity after intramuscular engraftment in dystrophin deficient mice.

    PubMed

    Sakai, Hiroshi; Sato, Takahiko; Sakurai, Hidetoshi; Yamamoto, Takuya; Hanaoka, Kazunori; Montarras, Didier; Sehara-Fujisawa, Atsuko

    2013-01-01

    Muscle satellite cells (SCs) are stem cells that reside in skeletal muscles and contribute to regeneration upon muscle injury. SCs arise from skeletal muscle progenitors expressing transcription factors Pax3 and/or Pax7 during embryogenesis in mice. However, it is unclear whether these fetal progenitors possess regenerative ability when transplanted in adult muscle. Here we address this question by investigating whether fetal skeletal muscle progenitors (FMPs) isolated from Pax3(GFP/+) embryos have the capacity to regenerate muscle after engraftment into Dystrophin-deficient mice, a model of Duchenne muscular dystrophy. The capacity of FMPs to engraft and enter the myogenic program in regenerating muscle was compared with that of SCs derived from adult Pax3(GFP/+) mice. Transplanted FMPs contributed to the reconstitution of damaged myofibers in Dystrophin-deficient mice. However, despite FMPs and SCs having similar myogenic ability in culture, the regenerative ability of FMPs was less than that of SCs in vivo. FMPs that had activated MyoD engrafted more efficiently to regenerate myofibers than MyoD-negative FMPs. Transcriptome and surface marker analyses of these cells suggest the importance of myogenic priming for the efficient myogenic engraftment. Our findings suggest the regenerative capability of FMPs in the context of muscle repair and cell therapy for degenerative muscle disease. PMID:23671652

  6. Fetal Skeletal Muscle Progenitors Have Regenerative Capacity after Intramuscular Engraftment in Dystrophin Deficient Mice

    PubMed Central

    Sakai, Hiroshi; Sato, Takahiko; Sakurai, Hidetoshi; Yamamoto, Takuya; Hanaoka, Kazunori; Montarras, Didier; Sehara-Fujisawa, Atsuko

    2013-01-01

    Muscle satellite cells (SCs) are stem cells that reside in skeletal muscles and contribute to regeneration upon muscle injury. SCs arise from skeletal muscle progenitors expressing transcription factors Pax3 and/or Pax7 during embryogenesis in mice. However, it is unclear whether these fetal progenitors possess regenerative ability when transplanted in adult muscle. Here we address this question by investigating whether fetal skeletal muscle progenitors (FMPs) isolated from Pax3GFP/+ embryos have the capacity to regenerate muscle after engraftment into Dystrophin-deficient mice, a model of Duchenne muscular dystrophy. The capacity of FMPs to engraft and enter the myogenic program in regenerating muscle was compared with that of SCs derived from adult Pax3GFP/+ mice. Transplanted FMPs contributed to the reconstitution of damaged myofibers in Dystrophin-deficient mice. However, despite FMPs and SCs having similar myogenic ability in culture, the regenerative ability of FMPs was less than that of SCs in vivo. FMPs that had activated MyoD engrafted more efficiently to regenerate myofibers than MyoD-negative FMPs. Transcriptome and surface marker analyses of these cells suggest the importance of myogenic priming for the efficient myogenic engraftment. Our findings suggest the regenerative capability of FMPs in the context of muscle repair and cell therapy for degenerative muscle disease. PMID:23671652

  7. Scallops show that muscle metabolic capacities reflect locomotor style and morphology.

    PubMed

    Tremblay, Isabelle; Guderley, Helga E

    2014-01-01

    Although all scallops swim using their adductor muscle to close their valves, scallop species differ considerably in how they use their muscle during escape responses, in parallel with the striking interspecific differences in shell morphology. This provides an excellent opportunity to study links between muscle metabolic capacities and animal performance. We found that the capacity for anaerobic glycolysis and aerobic metabolism, as well as phosphoarginine levels in the phasic adductor muscle, differ with escape response strategy. Phosphoarginine contents were high in species that rely on phasic contractions (Amusium balloti, Placopecten magellanicus, and Pecten fumatus). Arginine kinase activities reflect reliance on rapid initial bursts of phasic contractions. Scallops that maintain their valves in a closed position for prolonged periods (P. fumatus, Mimachlamys asperrima, and Crassadoma gigantea) have high activities of enzymes of anaerobic glycolysis in their phasic adductor muscle. Myosin ATPase activity was lower in the nonswimming scallop, C. gigantea, than in swimming scallops. The different patterns and roles of swimming are reflected in interspecific differences in the biochemical attributes of the phasic adductor muscle. These patterns suggest coevolution of muscle metabolic capacities, patterns of adductor muscle use, and shell morphology in scallops. PMID:24642541

  8. Water-holding capacity of broiler breast muscle during the first 24 h postmortem.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Water-holding capacity of poultry muscle influences both the sensory appeal for consumers and the product yield for processors. The underlying mechanisms that control water-holding capacity in poultry are not fully understood. The objective of this study was to determine the evolution of water-hol...

  9. Muscles do more positive than negative work in human locomotion

    PubMed Central

    DeVita, Paul; Helseth, Joseph; Hortobagyi, Tibor

    2008-01-01

    Summary Muscle work during level walking and ascent and descent ramp and stairway walking was assessed in order to explore the proposition that muscles perform more positive than negative work during these locomotion tasks. Thirty four healthy human adults were tested while maintaining a constant average walking velocity in the five gait conditions. Ground reaction force and sagittal plane kinematic data were obtained during the stance phases of these gaits and used in inverse dynamic analyses to calculate joint torques and powers at the hip, knee and ankle. Muscle work was derived as the area under the joint power vs time curves and was partitioned into positive, negative and net components. Dependent t-tests were used to compare positive and negative work in level walking and net joint work between ascent and descent gaits on the ramp and stairs (P<0.010). Total negative and positive work in level walking was −34 J and 50 J, respectively, with the difference in magnitude being statistically significant (P<0.001). Level walking was therefore performed with 16 J of net positive muscle work per step. The magnitude of the net work in ramp ascent was 25% greater than the magnitude of net work in ramp descent (89 vs −71 J m−1, P<0.010). Similarly, the magnitude of the net work in stair ascent was 43% greater than the magnitude of net work in stair descent (107 vs −75 J step−1, P<0.000). We identified three potential causes for the reduced negative vs positive work in these locomotion tasks: (1) the larger magnitude of the accelerations induced by the larger ground reaction forces in descending compared to ascending gaits elicited greater energy dissipation in non-muscular tissues, (2) the ground reaction force vector was directed closer to the joint centers in ramp and stair descent compared to ascent, which reduced the load on the muscular tissues and their energy dissipating response, and (3) despite the need to produce negative muscle work in descending

  10. TWEAK promotes exercise intolerance by decreasing skeletal muscle oxidative phosphorylation capacity

    PubMed Central

    2013-01-01

    Background Proinflammatory cytokine tumor necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK) and its receptor Fn14 are the major regulators of skeletal muscle mass in many catabolic conditions. However, their role in muscle metabolism remains largely unknown. In the present study, we investigated the role of TWEAK on exercise capacity and skeletal muscle mitochondrial content and oxidative metabolism. Methods We employed wild-type and TWEAK-knockout (KO) mice and primary myotube cultures and performed biochemical, bioenergetics, and morphometric assays to evaluate the effects of TWEAK on exercise tolerance and muscle mitochondrial function and angiogenesis. Results TWEAK-KO mice showed improved exercise tolerance compared to wild-type mice. Electron microscopy analysis showed that the abundance of subsarcolemmal and intermyofibrillar mitochondria is significantly increased in skeletal muscle of TWEAK-KO mice compared to wild-type mice. Furthermore, age-related loss in skeletal muscle oxidative capacity was rescued in TWEAK-KO mice. Expression of a key transcriptional regulator peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) and several other molecules involved in oxidative metabolism were significantly higher in skeletal muscle of TWEAK-KO mice. Moreover, treatment of primary myotubes with soluble TWEAK inhibited the expression of PGC-1α and mitochondrial genes and decreased mitochondrial respiratory capacity. Deletion of TWEAK also improved angiogenesis and transcript levels of vascular endothelial growth factor in skeletal muscle of mice. Conclusions These results demonstrate that TWEAK decreases mitochondrial content and oxidative phosphorylation and inhibits angiogenesis in skeletal muscle. Neutralization of TWEAK is a potential approach for improving exercise capacity and oxidative metabolism in skeletal muscle. PMID:23835416

  11. The AMPK activator R419 improves exercise capacity and skeletal muscle insulin sensitivity in obese mice

    PubMed Central

    Marcinko, Katarina; Bujak, Adam L.; Lally, James S.V.; Ford, Rebecca J.; Wong, Tammy H.; Smith, Brennan K.; Kemp, Bruce E.; Jenkins, Yonchu; Li, Wei; Kinsella, Todd M.; Hitoshi, Yasumichi; Steinberg, Gregory R.

    2015-01-01

    Objective Skeletal muscle AMP-activated protein kinase (AMPK) is important for regulating glucose homeostasis, mitochondrial content and exercise capacity. R419 is a mitochondrial complex-I inhibitor that has recently been shown to acutely activate AMPK in myotubes. Our main objective was to examine whether R419 treatment improves insulin sensitivity and exercise capacity in obese insulin resistant mice and whether skeletal muscle AMPK was important for mediating potential effects. Methods Glucose homeostasis, insulin sensitivity, exercise capacity, and electron transport chain content/activity were examined in wildtype (WT) and AMPK β1β2 muscle-specific null (AMPK-MKO) mice fed a high-fat diet (HFD) with or without R419 supplementation. Results There was no change in weight gain, adiposity, glucose tolerance or insulin sensitivity between HFD-fed WT and AMPK-MKO mice. In both HFD-fed WT and AMPK-MKO mice, R419 enhanced insulin tolerance, insulin-stimulated glucose disposal, skeletal muscle 2-deoxyglucose uptake, Akt phosphorylation and glucose transporter 4 (GLUT4) content independently of alterations in body mass. In WT, but not AMPK-MKO mice, R419 improved treadmill running capacity. Treatment with R419 increased muscle electron transport chain content and activity in WT mice; effects which were blunted in AMPK-MKO mice. Conclusions Treatment of obese mice with R419 improved skeletal muscle insulin sensitivity through a mechanism that is independent of skeletal muscle AMPK. R419 also increases exercise capacity and improves mitochondrial function in obese WT mice; effects that are diminished in the absence of skeletal muscle AMPK. These findings suggest that R419 may be a promising therapy for improving whole-body glucose homeostasis and exercise capacity. PMID:26413470

  12. Field tests for evaluating the aerobic work capacity of firefighters.

    PubMed

    Lindberg, Ann-Sofie; Oksa, Juha; Gavhed, Désirée; Malm, Christer

    2013-01-01

    Working as a firefighter is physically strenuous, and a high level of physical fitness increases a firefighter's ability to cope with the physical stress of their profession. Direct measurements of aerobic capacity, however, are often complicated, time consuming, and expensive. The first aim of the present study was to evaluate the correlations between direct (laboratory) and indirect (field) aerobic capacity tests with common and physically demanding firefighting tasks. The second aim was to give recommendations as to which field tests may be the most useful for evaluating firefighters' aerobic work capacity. A total of 38 subjects (26 men and 12 women) were included. Two aerobic capacity tests, six field tests, and seven firefighting tasks were performed. Lactate threshold and onset of blood lactate accumulation were found to be correlated to the performance of one work task (r(s) = -0.65 and -0.63, p<0.01, respectively). Absolute (mL · min(-1)) and relative (mL · kg(-1) · min(-1)) maximal aerobic capacity was correlated to all but one of the work tasks (r(s) = -0.79 to 0.55 and -0.74 to 0.47, p<0.01, respectively). Aerobic capacity is important for firefighters' work performance, and we have concluded that the time to row 500 m, the time to run 3000 m relative to body weight (s · kg(-1)), and the percent of maximal heart rate achieved during treadmill walking are the most valid field tests for evaluating a firefighter's aerobic work capacity. PMID:23844153

  13. Effect of inspiratory muscle work on peripheral fatigue of locomotor muscles in healthy humans

    PubMed Central

    Romer, Lee M; Lovering, Andrew T; Haverkamp, Hans C; Pegelow, David F; Dempsey, Jerome A

    2006-01-01

    The work of breathing required during maximal exercise compromises blood flow to limb locomotor muscles and reduces exercise performance. We asked if force output of the inspiratory muscles affected exercise-induced peripheral fatigue of locomotor muscles. Eight male cyclists exercised at ≥ 90% peak O2 uptake to exhaustion (CTRL). On a separate occasion, subjects exercised for the same duration and power output as CTRL (13.2 ± 0.9 min, 292 W), but force output of the inspiratory muscles was reduced (−56% versus CTRL) using a proportional assist ventilator (PAV). Subjects also exercised to exhaustion (7.9 ± 0.6 min, 292 W) while force output of the inspiratory muscles was increased (+80% versus CTRL) via inspiratory resistive loads (IRLs), and again for the same duration and power output with breathing unimpeded (IRL-CTRL). Quadriceps twitch force (Qtw), in response to supramaximal paired magnetic stimuli of the femoral nerve (1–100 Hz), was assessed pre- and at 2.5 through to 70 min postexercise. Immediately after CTRL exercise, Qtw was reduced −28 ± 5% below pre-exercise baseline and this reduction was attenuated following PAV exercise (−20 ± 5%; P < 0.05). Conversely, increasing the force output of the inspiratory muscles (IRL) exacerbated exercise-induced quadriceps muscle fatigue (Qtw=−12 ± 8% IRL-CTRL versus −20 ± 7% IRL; P < 0.05). Repeat studies between days showed that the effects of exercise per se, and of superimposed inspiratory muscle loading on quadriceps fatigue were highly reproducible. In conclusion, peripheral fatigue of locomotor muscles resulting from high-intensity sustained exercise is, in part, due to the accompanying high levels of respiratory muscle work. PMID:16373384

  14. Effect of contrasting physical exercise interventions on rapid force capacity of chronically painful muscles.

    PubMed

    Andersen, Lars L; Andersen, Jesper L; Suetta, Charlotte; Kjaer, Michael; Søgaard, Karen; Sjøgaard, Gisela

    2009-11-01

    Rapid force capacity of chronically painful muscles is inhibited markedly more than maximal force capacity and is therefore relevant to assess in rehabilitation settings. Our objective was to investigate the effect of two contrasting types of physical exercise on rapid force capacity, as well as neural and muscular adaptations in women with chronic neck muscle pain. A group of employed women (n = 42) with a clinical diagnosis of trapezius myalgia participated in a 10-wk randomized controlled trial; specific strength training of the neck/shoulder muscles, general fitness training performed as leg-bicycling; or a reference intervention without physical activity. Maximal voluntary shoulder abductions were performed at static angles of 35 degrees and 115 degrees with simultaneous recording of electromyography (EMG) in the trapezius and deltoid. Maximal muscle strength and activation (peak torque and peak EMG) as well as rapid muscle strength and activation [rate of torque development (RTD) and rate of EMG rise] were subsequently determined. Trapezius muscle fiber characteristics were determined with ATPase histochemistry. Significant changes were observed only in the specific strength training group. Whereas peak torque increased 18-29% (P < 0.01), RTD increased 61-115% (P < 0.001). Peak EMG and rate of EMG rise increased correspondingly (P < 0.05-0.001), and trapezius type II muscle fibers hypertrophied 20% (P < 0.001). In conclusion, rapid force capacity of chronically painful muscles is highly responsive to rehabilitation with specific strength training. The underlying mechanisms were related to both pain reduction and general neuromuscular adaptations to strength training. Potentially, the present method can be a useful clinical screening tool of muscle function in rehabilitation settings. PMID:19762523

  15. Capacity estimates in working memory: Reliability and interrelationships among tasks.

    PubMed

    Van Snellenberg, Jared X; Conway, Andrew R A; Spicer, Julie; Read, Christina; Smith, Edward E

    2014-03-01

    The concept of capacity has become increasingly important in discussions of working memory (WM), in so far as most models of WM conceptualize it as a limited-capacity mechanism for maintaining information in an active state, and as capacity estimates from at least one type of WM task-complex span-are valid predictors of real-world cognitive performance. However, the term capacity is also often used in the context of a distinct set of WM tasks, change detection, and may or may not refer to the same cognitive capability. We here develop maximum-likelihood models of capacity from each of these tasks-as well as from a third WM task that places heavy demands on cognitive control, the self-ordered WM task (SOT)-and show that the capacity estimates from change detection and complex span tasks are not correlated with each other, although capacity estimates from change detection tasks do correlate with those from the SOT. Furthermore, exploratory factor analysis confirmed that performance on the SOT and change detection load on the same factor, with performance on our complex span task loading on its own factor. These findings suggest that at least two distinct cognitive capabilities underlie the concept of WM capacity as it applies to each of these three tasks. PMID:24399681

  16. Skeletal muscle adiposity is associated with physical activity, exercise capacity and fibre shift in COPD.

    PubMed

    Maddocks, Matthew; Shrikrishna, Dinesh; Vitoriano, Simone; Natanek, Samantha A; Tanner, Rebecca J; Hart, Nicholas; Kemp, Paul R; Moxham, John; Polkey, Michael I; Hopkinson, Nicholas S

    2014-11-01

    Quadriceps muscle phenotype varies widely between patients with chronic obstructive pulmonary disease (COPD) and cannot be determined without muscle biopsy. We hypothesised that measures of skeletal muscle adiposity could provide noninvasive biomarkers of muscle quality in this population. In 101 patients and 10 age-matched healthy controls, mid-thigh cross-sectional area, percentage intramuscular fat and skeletal muscle attenuation were calculated using computed tomography images and standard tissue attenuation ranges: fat -190- -30 HU; skeletal muscle -29-150 HU. Mean±sd percentage intramuscular fat was higher in the patient group (6.7±3.5% versus 4.3±1.2%, p = 0.03). Both percentage intramuscular fat and skeletal muscle attenuation were associated with physical activity level, exercise capacity and type I fibre proportion, independent of age, mid-thigh cross-sectional area and quadriceps strength. Combined with transfer factor of the lung for carbon monoxide, these variables could identify >80% of patients with fibre type shift with >65% specificity (area under the curve 0.83, 95% CI 0.72-0.95). Skeletal muscle adiposity assessed by computed tomography reflects multiple aspects of COPD related muscle dysfunction and may help to identify patients for trials of interventions targeted at specific muscle phenotypes. PMID:24993908

  17. Specificity of aerobic and anaerobic work capacities and powers.

    PubMed

    Boulay, M R; Lortie, G; Simoneau, J A; Hamel, P; Leblanc, C; Bouchard, C

    1985-12-01

    Thirty-three untrained subjects of both sexes, 18-31 years of age, performed several tests on cycle ergometers. Maximal aerobic power (MAP) was obtained in a progressive work test. Maximal aerobic capacity (MAC) was measured in a 90-min maximal test and was computed as the total work output during that period. Two all-out cycle ergometer work tests lasting 10 s and 90 s were used to estimate the anaerobic alactic capacity (AAC) and lactic capacity (ALC). Anaerobic alactic power (AAP) was computed as the highest output in 1 s in the AAC test and anaerobic lactic power (ALP) was obtained as the mean output during the last 5 s in an all-out test of 30 s. Correlation coefficients were computed between all measurements of capacity and power expressed per kg of body weight as well as with scores adjusted for sex differences. Common variances (r2 X 100) between measurements of power were either low (MAP-AAP, 40%) or moderate (MAP-ALP, 61%; AAP-ALP, 62%) while common variances between measurements of capacity were sometimes low (MAC-AAC, 49%) or higher (MAC-ALC, 76%; AAC-ALC, 77%). The common variances between tests of power and capacity reached high values when calculated with metabolic criteria of the same class (MAP-MAC, 81%; AAP-AAC, 92%). These results provide quantitative evidence to support the notion of specificity between the aerobic and the anaerobic work performances and support the distinction between capacity and power of the three energy systems. PMID:4077360

  18. Influence of exercise training with resveratrol supplementation on skeletal muscle mitochondrial capacity.

    PubMed

    Polley, Kristine R; Jenkins, Nathan; O'Connor, Patrick; McCully, Kevin

    2016-01-01

    Physical inactivity reduces, and exercise training increases, mitochondrial capacity. In rodents, exercise training effects can be augmented by large doses of resveratrol supplementation but whether this can occur in humans with a smaller dose is unclear. This study sought to determine the effects of resveratrol supplementation in combination with exercise training on skeletal muscle mitochondrial capacity. Sixteen healthy young adults were randomly assigned in a double-blind fashion to consume either placebo or 500 mg of resveratrol plus 10 mg of piperine, a bioenhancer to increase bioavailibilty and bioefficacy of resveratrol. Participants ingested the pills daily for 4 weeks and completed 3 sessions per week of submaximal endurance training of the wrist flexor muscles of the nondominant arm. The contralateral arm served as an untrained control. Skeletal muscle mitochondrial capacity was measured using near-infrared spectroscopy. Changes in mitochondrial capacity from baseline to post-testing indicated significant differences between the resveratrol+piperine-trained arm and the placebo-trained arm (p = 0.02), with the resveratrol+piperine group increasing about 40% from baseline (Δk = 0.58), while the placebo group increased about 10% from baseline (Δk = 0.13). Neither the placebo group nor the resveratrol+piperine group exhibited changes in mitochondrial capacity in the untrained arm. In conclusion, low-intensity exercise training can increase forearm skeletal muscle mitochondrial capacity when combined with resveratrol and piperine supplementation. PMID:26638911

  19. Estimating Working Memory Capacity for Lists of Nonverbal Sounds

    PubMed Central

    Li, Dawei; Cowan, Nelson; Saults, J. Scott

    2012-01-01

    Working memory (WM) capacity limit has been extensively studied in the domains of visual and verbal stimuli. Previous studies have suggested a fixed WM capacity of typically about 3 or 4 items, based on the number of items in working memory reaching a plateau after several items as the set size increases. However, the fixed WM capacity estimate appears to rely on categorical information in the stimulus set (Olsson & Poom, 2005). We designed a series of experiments to investigate nonverbal auditory WM capacity and its dependence on categorical information. Experiments 1 and 2 used simple tones and revealed capacity limit of up to 2 tones following a 6-s retention interval. Importantly, performance was significantly higher at set sizes 2, 3, and 4 when the frequency difference between target and test tones was relatively large. In Experiment 3, we added categorical information to the simple tones, and the effect of tone change magnitude decreased. Maximal capacity for each individual was just over 3 sounds, in the range of typical visual procedures. We propose that two types of information, categorical and detailed acoustic information, are kept in WM, and that categorical information is critical for high WM performance. PMID:23143913

  20. Effect of endurance training on glucose transport capacity and glucose transporter expression in rat skeletal muscle

    SciTech Connect

    Ploug, T.; Stallknecht, B.M.; Pedersen, O.; Kahn, B.B.; Ohkuwa, T.; Vinten, J.; Galbo, H. )

    1990-12-01

    The effect of 10 wk endurance swim training on 3-O-methylglucose (3-MG) uptake (at 40 mM 3-MG) in skeletal muscle was studied in the perfused rat hindquarter. Training resulted in an increase of approximately 33% for maximum insulin-stimulated 3-MG transport in fast-twitch red fibers and an increase of approximately 33% for contraction-stimulated transport in slow-twitch red fibers compared with nonexercised sedentary muscle. A fully additive effect of insulin and contractions was observed both in trained and untrained muscle. Compared with transport in control rats subjected to an almost exhaustive single exercise session the day before experiment both maximum insulin- and contraction-stimulated transport rates were increased in all muscle types in trained rats. Accordingly, the increased glucose transport capacity in trained muscle was not due to a residual effect of the last training session. Half-times for reversal of contraction-induced glucose transport were similar in trained and untrained muscles. The concentrations of mRNA for GLUT-1 (the erythrocyte-brain-Hep G2 glucose transporter) and GLUT-4 (the adipocyte-muscle glucose transporter) were increased approximately twofold by training in fast-twitch red muscle fibers. In parallel to this, Western blot demonstrated a approximately 47% increase in GLUT-1 protein and a approximately 31% increase in GLUT-4 protein. This indicates that the increases in maximum velocity for 3-MG transport in trained muscle is due to an increased number of glucose transporters.

  1. Inducible depletion of satellite cells in adult, sedentary mice impairs muscle regenerative capacity without affecting sarcopenia.

    PubMed

    Fry, Christopher S; Lee, Jonah D; Mula, Jyothi; Kirby, Tyler J; Jackson, Janna R; Liu, Fujun; Yang, Lin; Mendias, Christopher L; Dupont-Versteegden, Esther E; McCarthy, John J; Peterson, Charlotte A

    2015-01-01

    A key determinant of geriatric frailty is sarcopenia, the age-associated loss of skeletal muscle mass and strength. Although the etiology of sarcopenia is unknown, the correlation during aging between the loss of activity of satellite cells, which are endogenous muscle stem cells, and impaired muscle regenerative capacity has led to the hypothesis that the loss of satellite cell activity is also a cause of sarcopenia. We tested this hypothesis in male sedentary mice by experimentally depleting satellite cells in young adult animals to a degree sufficient to impair regeneration throughout the rest of their lives. A detailed analysis of multiple muscles harvested at various time points during aging in different cohorts of these mice showed that the muscles were of normal size, despite low regenerative capacity, but did have increased fibrosis. These results suggest that lifelong reduction of satellite cells neither accelerated nor exacerbated sarcopenia and that satellite cells did not contribute to the maintenance of muscle size or fiber type composition during aging, but that their loss may contribute to age-related muscle fibrosis. PMID:25501907

  2. Influence of exercise training on the oxidative capacity of rat abdominal muscles

    NASA Technical Reports Server (NTRS)

    Uribe, J. M.; Stump, C. S.; Tipton, C. M.; Fregosi, R. F.

    1992-01-01

    Our purpose was to determine if endurance exercise training would increase the oxidative capacity of the abdominal expiratory muscles of the rat. Accordingly, 9 male rats were subjected to an endurance training protocol (1 h/day, 6 days/week, 9 weeks) and 9 litter-mates served as controls. Citrate synthase (CS) activity was used as an index of oxidative capacity, and was determined in the following muscles: soleus, plantaris, costal diaphragm, crural diaphragm, and in all four abdominal muscles: rectus abdominis, transversus abdominis, external oblique, and internal oblique. Compared to their non-trained litter-mates, the trained rats had higher peak whole body oxygen consumption rates (+ 16%) and CS activities in plantaris (+34%) and soleus (+36%) muscles. Thus, the training program caused substantial systemic and locomotor muscle adaptations. The CS activity of costal diaphragm was 20% greater in the trained animals, but no difference was observed in crural diaphragm. The CS activity in the abdominal muscles was less than one-half of that in locomotor and diaphragm muscles, and there were no significant changes with training except in the rectus abdominis where a 26% increase was observed. The increase in rectus abdominis CS activity may reflect its role in postural support and/or locomotion, as none of the primary expiratory pumping muscles adapted to the training protocol. The relatively low levels of CS activity in the abdominal muscles suggests that they are not recruited frequently at rest, and the lack of an increase with training indicates that these muscles do not contribute significantly to the increased ventilatory activity accompanying exercise in the rat.

  3. Assessing Working Memory Capacity in a Non-Native Language

    ERIC Educational Resources Information Center

    Sanchez, Christopher A.; Wiley, Jennifer; Miura, Timothy K.; Colflesh, Gregory J. H.; Ricks, Travis R.; Jensen, Melinda S.; Conway, Andrew R. A.

    2010-01-01

    The present studies directly test the usefulness of two English-language working memory capacity (WMC) assessments with two samples of students whose native language was not English. Participants completed two widely used complex span tasks, Reading Span (RSpan) and Operation Span (OSpan), in English. To determine whether the well-established…

  4. Individual Differences in the Fan Effect and Working Memory Capacity

    ERIC Educational Resources Information Center

    Bunting, M.F.; Conway, A.R.A.; Heitz, R.P.

    2004-01-01

    In opposition to conceptualizing working memory (WM) in terms of a general capacity, we present four experiments that favor the view that individual differences in WM depend on attentional control. High- and low-WM participants, as assessed by the operation span task, learned unrelated sentences for which the subject and predicate of the sentences…

  5. The influence of inspiratory muscle work history and specific inspiratory muscle training upon human limb muscle fatigue

    PubMed Central

    McConnell, Alison K; Lomax, Michelle

    2006-01-01

    The purpose of this study was to assess the influence of the work history of the inspiratory muscles upon the fatigue characteristics of the plantar flexors (PF). We hypothesized that under conditions where the inspiratory muscle metaboreflex has been elicited, PF fatigue would be hastened due to peripheral vasoconstriction. Eight volunteers undertook seven test conditions, two of which followed 4 week of inspiratory muscle training (IMT). The inspiratory metaboreflex was induced by inspiring against a calibrated flow resistor. We measured torque and EMG during isometric PF exercise at 85% of maximal voluntary contraction (MVC) torque. Supramaximal twitches were superimposed upon MVC efforts at 1 min intervals (MVCTI); twitch interpolation assessed the level of central activation. PF was terminated (Tlim) when MVCTI was <50% of baseline MVC. PF Tlim was significantly shorter than control (9.93 ± 1.95 min) in the presence of a leg cuff inflated to 140 mmHg (4.89 ± 1.78 min; P = 0.006), as well as when PF was preceded immediately by fatiguing inspiratory muscle work (6.28 ± 2.24 min; P = 0.009). Resting the inspiratory muscles for 30 min restored the PF Tlim to control. After 4 weeks, IMT, inspiratory muscle work at the same absolute intensity did not influence PF Tlim, but Tlim was significantly shorter at the same relative intensity. The data are the first to provide evidence that the inspiratory muscle metaboreflex accelerates the rate of calf fatigue during PF, and that IMT attenuates this effect. PMID:16973699

  6. Substrate oxidation capacity in rodent skeletal muscle: effects of exposure to zero gravity

    NASA Technical Reports Server (NTRS)

    Baldwin, K. M.; Herrick, R. E.; McCue, S. A.

    1993-01-01

    A study was conducted, as part of the integrated National Aeronautics and Space Administration Space Life Sciences 1 mission flown in June of 1991, to ascertain the effects of 9 days of exposure to zero gravity on the capacity of rodent skeletal muscle fiber types to oxidize either [14C]pyruvate or [14C]palmitate under state 3 metabolic conditions, i.e., nonlimiting amounts of substrate and cofactors. In addition, activity levels of marker enzymes of the tricarboxylic acid cycle, malate shuttle, and beta-oxidation were measured. Results showed that significant differences in muscle weight occurred in both the predominantly slow vastus intermedius and predominantly fast vastus lateralis of flight vs. control groups (P < 0.05). Total protein content of the muscle samples was similar between groups. Both pyruvate oxidation capacity and the marker oxidative enzymes were not altered in the flight relative to control animals. However, the capacity to oxidize long-chain fatty acids was significantly reduced by 37% in both the high- and low-oxidative regions of the vastus muscle (P < 0.05). Although these findings of a selective reduction in fatty acid oxidation capacity in response to spaceflight are surprising, they are consistent with previous findings showing 1) an increased capacity to take up glucose and upregulate glucose transporter proteins and 2) a marked accumulation of triglycerides in the skeletal muscles of rats subjected to states of unloading. Thus, skeletal muscle of animals exposed to non-weight-bearing environments undergo subcellular transformations that may preferentially bias energy utilization to carbohydrates.

  7. Intrinsic foot muscles have the capacity to control deformation of the longitudinal arch

    PubMed Central

    Kelly, Luke A.; Cresswell, Andrew G.; Racinais, Sebastien; Whiteley, Rodney; Lichtwark, Glen

    2014-01-01

    The human foot is characterized by a pronounced longitudinal arch (LA) that compresses and recoils in response to external load during locomotion, allowing for storage and return of elastic energy within the passive structures of the arch and contributing to metabolic energy savings. Here, we examine the potential for active muscular contribution to the biomechanics of arch deformation and recoil. We test the hypotheses that activation of the three largest plantar intrinsic foot muscles, abductor hallucis, flexor digitorum and quadratus plantae is associated with muscle stretch in response to external load on the foot and that activation of these muscles (via electrical stimulation) will generate sufficient force to counter the deformation of LA caused by the external load. We found that recruitment of the intrinsic foot muscles increased with increasing load, beyond specific load thresholds. Interestingly, LA deformation and muscle stretch plateaued towards the maximum load of 150% body weight, when muscle activity was greatest. Electrical stimulation of the plantar intrinsic muscles countered the deformation that occurred owing to the application of external load by reducing the length and increasing the height of the LA. These findings demonstrate that these muscles have the capacity to control foot posture and LA stiffness and may provide a buttressing effect during foot loading. This active arch stiffening mechanism may have important implications for how forces are transmitted during locomotion and postural activities as well as consequences for metabolic energy saving. PMID:24478287

  8. Enhanced exercise and regenerative capacity in a mouse model that violates size constraints of oxidative muscle fibres.

    PubMed

    Omairi, Saleh; Matsakas, Antonios; Degens, Hans; Kretz, Oliver; Hansson, Kenth-Arne; Solbrå, Andreas Våvang; Bruusgaard, Jo C; Joch, Barbara; Sartori, Roberta; Giallourou, Natasa; Mitchell, Robert; Collins-Hooper, Henry; Foster, Keith; Pasternack, Arja; Ritvos, Olli; Sandri, Marco; Narkar, Vihang; Swann, Jonathan R; Huber, Tobias B; Patel, Ketan

    2016-01-01

    A central tenet of skeletal muscle biology is the existence of an inverse relationship between the oxidative fibre capacity and its size. However, robustness of this relationship is unknown. We show that superimposition of Estrogen-related receptor gamma (Errγ) on the myostatin (Mtn) mouse null background (Mtn(-/-)/Errγ(Tg/+)) results in hypertrophic muscle with a high oxidative capacity thus violating the inverse relationship between fibre size and oxidative capacity. We also examined the canonical view that oxidative muscle phenotype positively correlate with Satellite cell number, the resident stem cells of skeletal muscle. Surprisingly, hypertrophic fibres from Mtn(-/-)/Errγ(Tg/+) mouse showed satellite cell deficit which unexpectedly did not affect muscle regeneration. These observations 1) challenge the concept of a constraint between fibre size and oxidative capacity and 2) indicate the important role of the microcirculation in the regenerative capacity of a muscle even when satellite cell numbers are reduced. PMID:27494364

  9. Functional Overloading of Dystrophic Mice Enhances Muscle-Derived Stem Cell Contribution to Muscle Contractile Capacity

    PubMed Central

    Ambrosio, Fabrisia; Ferrari, Ricardo J.; Fitzgerald, G. Kelley; Carvell, George; Boninger, Michael L.; Huard, Johnny

    2016-01-01

    Objectives To evaluate the effect of functional overloading on the transplantation of muscle derived stem cells (MDSCs) into dystrophic muscle and the ability of transplanted cells to increase dystrophic muscle’s ability to resist overloading-induced weakness. Design Cross-sectional. Setting Laboratory. Animals Male mice (N=10) with a dystrophin gene mutation. Interventions MDSCs were intramuscularly transplanted into the extensor digitorum longus muscle (EDL). Functional overloading of the EDL was performed by surgical ablation of the EDL’s synergist. Main Outcome Measures The total number of dystrophin-positive fibers/cross-section (as a measure of stem cell engraftment), the average number of CD31+ cells (as a measure of capillarity), and in vitro EDL contractile strength. Independent t tests were used to investigate the effect of overloading on engraftment, capillarity, and strength. Paired t tests were used to investigate the effect of MDSC engraftment on strength and capillarity. Results MDSC transplantation protects dystrophic muscles against overloading-induced weakness (specific twitch force: control 4.5N/cm2±2.3; MDSC treated 7.9N/cm2±1.4) (P=.02). This improved force production following overloading is concomitant with an increased regeneration by transplanted MDSCs (MDSC: 26.6±20.2 dystrophin-positive fibers/cross-section; overloading + MDSC: 170.6±130.9 dystrophin-positive fibers/cross-section [P=.03]). Overloading-induced increases in skeletal muscle capillarity is significantly correlated with increased MDSC engraftment (R2=.80, P=.01). Conclusions These findings suggest that the functional contribution of transplanted MDSCs may rely on activity-dependent mechanisms, possibly mediated by skeletal muscle vascularity. Rehabilitation modalities may play an important role in the development of stem cell transplantation strategies for the treatment of muscular dystrophy. PMID:19154831

  10. Knowledge Cannot Explain the Developmental Growth of Working Memory Capacity

    PubMed Central

    Cowan, Nelson; Ricker, Timothy J.; Clark, Katherine M.; Hinrichs, Garrett A.; Glass, Bret A.

    2014-01-01

    According to some views of cognitive growth, the development of working memory capacity can account for increases in the complexity of cognition. It has been difficult to ascertain, though, that there actually is developmental growth in capacity that cannot be attributed to other developing factors. Here we assess the role of item familiarity. We document developmental increases in working memory for visual arrays of English letters versus unfamiliar characters. Although letter knowledge played a special role in development between the ages of 6 to 8 years, children with adequate letter knowledge showed practically the same developmental growth in normalized functions for letters and unfamiliar characters. The results contribute to a growing body of evidence that the developmental improvement in working memory does not wholly stem from supporting processes such as encoding, mnemonic strategies, and knowledge. PMID:24942111

  11. Knowledge cannot explain the developmental growth of working memory capacity.

    PubMed

    Cowan, Nelson; Ricker, Timothy J; Clark, Katherine M; Hinrichs, Garrett A; Glass, Bret A

    2015-01-01

    According to some views of cognitive growth, the development of working memory capacity can account for increases in the complexity of cognition. It has been difficult to ascertain, though, that there actually is developmental growth in capacity that cannot be attributed to other developing factors. Here we assess the role of item familiarity. We document developmental increases in working memory for visual arrays of English letters versus unfamiliar characters. Although letter knowledge played a special role in development between the ages of 6 and 8 years, children with adequate letter knowledge showed practically the same developmental growth in normalized functions for letters and unfamiliar characters. The results contribute to a growing body of evidence that the developmental improvement in working memory does not wholly stem from supporting processes such as encoding, mnemonic strategies, and knowledge. A video abstract is available at: https://www.youtube.com/watch?v=LJdqErLR2Hs&feature=youtu.be. PMID:24942111

  12. Obese humans as economically designed feed converters: symmorphosis and low oxidative capacity skeletal muscle.

    PubMed

    Hudson, Nicholas J; Lehnert, Sigrid A; Harper, Gregory S

    2008-01-01

    Human obesity is considered a consequence of a thrifty or economic metabolism. In this hypothesis, we apply an established economic design theory, called symmorphosis, to help explain the known association between obesity and low oxidative capacity skeletal muscle. Symmorphosis reflects an engineering principle, and predicts that physiological systems are most economically designed when unnecessary spare capacity is eliminated. This is because the structural/functional adaptations accounting for spare capacity themselves bear energetic costs of construction, maintenance and load. As oxidation of feed energy occurs in mitochondria, and because skeletal muscle accounts for 30% of resting metabolism, we focus on skeletal muscle mitochondria. In the same way that the most economically designed elevator is supported by a cable that is strong enough, but not too strong, symmorphosis predicts that the most economically designed feed converters should have enough, but not too much mitochondrial oxidative (fuel burning) capacity. While ATP demand is clearly more efficiently met by oxidative (38 molecules of ATP) rather than glycolytic (2 molecules of ATP) metabolism, symmorphosis predicts that having excess oxidative capacity actually reduces feed efficiency. This inefficiency is manifest by having to maintain, ultimately using feed energy, the expensive inner mitochondrial proton gradient in the superfluous mitochondria. On this basis, we predict that established molecular controllers of mitochondrial biogenesis and oxidative capacity such as eNOS, SIN3 co-repressor, TFAM and PPARgamma may yield useful DNA markers and therapeutic targets for issues relating to frugal energetics, namely predisposition to obesity and starvation resilience. PMID:17664046

  13. Muscle force regulates bone shaping for optimal load-bearing capacity during embryogenesis.

    PubMed

    Sharir, Amnon; Stern, Tomer; Rot, Chagai; Shahar, Ron; Zelzer, Elazar

    2011-08-01

    The vertebrate skeleton consists of over 200 individual bones, each with its own unique shape, size and function. We study the role of intrauterine muscle-induced mechanical loads in determining the three-dimensional morphology of developing bones. Analysis of the force-generating capacity of intrauterine muscles in mice revealed that developing bones are subjected to significant and progressively increasing mechanical challenges. To evaluate the effect of intrauterine loads on bone morphogenesis and the contribution of the emerging shape to the ability of bones to withstand these loads, we monitored structural and mineral changes during development. Using daily micro-CT scans of appendicular long bones we identify a developmental program, which we term preferential bone growth, that determines the specific circumferential shape of each bone by employing asymmetric mineral deposition and transient cortical thickening. Finite element analysis demonstrates that the resulting bone structure has optimal load-bearing capacity. To test the hypothesis that muscle forces regulate preferential bone growth in utero, we examine this process in a mouse strain (mdg) that lacks muscle contractions. In the absence of mechanical loads, the stereotypical circumferential outline of each bone is lost, leading to the development of mechanically inferior bones. This study identifies muscle force regulation of preferential bone growth as the module that shapes the circumferential outline of bones and, consequently, optimizes their load-bearing capacity during development. Our findings invoke a common mechanism that permits the formation of different circumferential outlines in different bones. PMID:21750035

  14. Rev-erb-α modulates skeletal muscle oxidative capacity by regulating mitochondrial biogenesis and autophagy

    PubMed Central

    Woldt, Estelle; Sebti, Yasmine; Solt, Laura A.; Duhem, Christian; Lancel, Steve; Eeckhoute, Jérôme; Hesselink, Matthijs K.C.; Paquet, Charlotte; Delhaye, Stéphane; Shin, Youseung; Kamenecka, Theodore M.; Schaart, Gert; Lefebvre, Philippe; Nevière, Rémi; Burris, Thomas P.; Schrauwen, Patrick; Staels, Bart; Duez, Hélène

    2013-01-01

    The nuclear receptor Rev-erb-α modulates hepatic lipid and glucose metabolism, adipogenesis and the inflammatory response in macrophages. We show here that Rev-erb-α is highly expressed in oxidative skeletal muscle and plays a role in mitochondrial biogenesis and oxidative function, in gain- and loss-of function studies. Rev-erb-α-deficiency in skeletal muscle leads to reduced mitochondrial content and oxidative function, resulting in compromised exercise capacity. This phenotype was recapitulated in isolated fibers and in muscle cells upon Rev-erbα knock-down, while Rev-erb-α over-expression increased the number of mitochondria with improved respiratory capacity. Rev-erb-α-deficiency resulted in deactivation of the Stk11–Ampk–Sirt1–Ppargc1-α signaling pathway, whereas autophagy was up-regulated, resulting in both impaired mitochondrial biogenesis and increased clearance. Muscle over-expression or pharmacological activation of Rev-erb-α increased respiration and exercise capacity. This study identifies Rev-erb-α as a pharmacological target which improves muscle oxidative function by modulating gene networks controlling mitochondrial number and function. PMID:23852339

  15. Working memory capacity of biological movements predicts empathy traits.

    PubMed

    Gao, Zaifeng; Ye, Tian; Shen, Mowei; Perry, Anat

    2016-04-01

    Working memory (WM) and empathy are core issues in cognitive and social science, respectively. However, no study so far has explored the relationship between these two constructs. Considering that empathy takes place based on the others' observed experiences, which requires extracting the observed dynamic scene into WM and forming a coherent representation, we hypothesized that a sub-type of WM capacity, i.e., WM for biological movements (BM), should predict one's empathy level. Therefore, WM capacity was measured for three distinct types of stimuli in a change detection task: BM of human beings (BM; Experiment 1), movements of rectangles (Experiment 2), and static colors (Experiment 3). The first two stimuli were dynamic and shared one WM buffer which differed from the WM buffer for colors; yet only the BM conveyed social information. We found that BM-WM capacity was positively correlated with both cognitive and emotional empathy, with no such correlations for WM capacity of movements of rectangles or of colors. Thus, the current study is the first to provide evidence linking a specific buffer of WM and empathy, and highlights the necessity for considering different WM capacities in future social and clinical research. PMID:26174575

  16. Effects of forward head posture on forced vital capacity and respiratory muscles activity.

    PubMed

    Han, Jintae; Park, Soojin; Kim, Youngju; Choi, Yeonsung; Lyu, Hyeonnam

    2016-01-01

    [Purpose] This study investigated the effects of forward head posture on forced vital capacity and deep breathing. [Subjects] Twenty-six subjects, divided into the two groups (normal and forward head posture groups), participated in this study. [Methods] Forced vital capacity and forced expiratory volume in 1 second were measured using respiratory function instrumentation that met the American Thoracic Society's recommendation for diagnostic spirometry. Accessory respiratory muscle activity during deep breathing was measured by electromyography. A Mann-Whitney test was used to compare the measure variables between the normal and forward head posture group. [Results] Forced vital capacity and forced expiratory volume in 1 second were significantly lower in the forward head posture group than in the normal group. Accessory respiratory muscle activity was also lower in the forward head posture group than in the normal group. In particular, the sternocleidomastoid and pectoralis major activity of the forward head posture group was significantly lower than that of normal group. Activities of the other muscles were generally decreased with forward head posture, but were not significantly different between the two groups. [Conclusion] These results indicate that forward head posture could reduce vital capacity, possibly because of weakness or disharmony of the accessory respiratory muscles. PMID:26957743

  17. Angiotensin-II blockage, muscle strength, and exercise capacity in physically independent older adults

    PubMed Central

    Coelho, Vinícius A.; Probst, Vanessa S.; Nogari, Bruna M.; Teixeira, Denilson C.; Felcar, Josiane M.; Santos, Denis C.; Gomes, Marcus Vinícius M.; Andraus, Rodrigo A. C.; Fernandes, Karen B. P.

    2016-01-01

    [Purpose] This study aimed to assess the exercise capacity and muscle strength in elderly people using drugs for angiotensin-II blockage. [Subjects and Methods] Four hundred and seven older adults were recruited for this study. Data about comorbidities and medication use were recorded and the individuals were divided into three groups: control group- elderly people with normal exercise capacity (n=235); angiotensin-converting enzyme inhibitor group − individuals using angiotensin-converting enzyme inhibitors (n=140); and angiotensin-II receptor blocker group- patients using angiotensin-II receptor blockers (n= 32). Exercise capacity was evaluated by a 6-minute walking test and muscle strength was measured using a handgrip dynamometer. [Results] Patients from the angiotensin-converting enzyme inhibitor group (mean: 99 ± 12%) and the angiotensin-II receptor blocker group (mean: 101 ± 14%) showed higher predicted values in the 6-minute walking test than the control group patients (mean: 96 ± 10%). Patients from the angiotensin-converting enzyme inhibitor group (mean: 105 ± 19%) and the angiotensin-II receptor blocker group (mean: 105.1 ± 18.73%) showed higher predicted values of muscle strength than control group patients (mean: 98.15 ± 18.77%). [Conclusion] Older adults using angiotensin-converting enzyme inhibitors or angiotensin-II receptor blockers have better functional exercise capacity and muscle strength. PMID:27065543

  18. Increased intrinsic mitochondrial respiratory capacity in skeletal muscle from rats with streptozotocin-induced hyperglycemia

    PubMed Central

    Larsen, Steen; Scheede-Bergdahl, Celena; Whitesell, Thomas; Boushel, Robert; Bergdahl, Andreas

    2015-01-01

    Type I diabetes mellitus (T1DM) is a chronic disorder, characterized by an almost or complete insulin deficiency. Widespread tissue dysfunction and deleterious diabetes-complications are associated with long-term elevations of blood glucose. The aim of this study was to investigate the effects of type I diabetes, as induced by streptozotocin, on the mitochondria in skeletal muscles that predominantly consist of either slow or fast twitch fibers. Soleus (primarily slow twitch fiber type) and the plantaris muscle (mainly fast twitch fiber type) were removed in order to measure mitochondrial protein expression and integrated mitochondrial respiratory function. Mitochondrial capacity for oxidative phosphorylation (OXPHOS) was found to be higher in the slow (more oxidative) soleus muscle from STZ rats when evaluating lipid and complex I linked OXPHOS capacity, whereas no difference was detected between the groups when evaluating the more physiological complex I and II linked OXPHOS capacity. These findings indicate that chronic hyperglycemia results in an elevated intrinsic mitochondrial respiratory capacity in both soleus and, at varying degree, plantaris muscle, findings that are consistent with human T1DM patients. PMID:26197936

  19. Effect of primary hypohydration on physical work capacity

    NASA Astrophysics Data System (ADS)

    Pichan, G.; Gauttam, R. K.; Tomar, O. S.; Bajaj, A. C.

    1988-09-01

    Physical work capacity (PWC180) was assessed with different levels of hypohydration in 25 heat-acclimatized male volunteers in hot dry (45°C DB, 30% RH) and hot humid (39°C DB, 60% RH) conditions equated to a heat stress level of 34°C on the WBGT scale. Heat acclimatization was carried out by exposing the subjects for 8 consecutive days in a climatic chamber with moderate work for two 50 min work cycles and 10 min intervening rest pauses. Acclimatization resulted in significant decreases in heart rate (27 bpm), oral temperature (0.8°C), mean skin temperature (1.2°C) and a significant increase in sweating rate (120 g h-1 m-2). Day-to-day variations in body hypohydration levels during heat acclimatization were not significantly different, although water intake was found to increase significantly from day 3 onwards when the subjects were in ad lib water intake state. The heat acclimatized subjects were then hypohydrated to varying degrees, viz. 1%, 2% and 3% body weight deficit, with moderate work in heat in the climatic chamber and after successful recovery from the effects of thermal stress and exercise; their physical work capacity was assessed individually. Physical work capacity was found to decrease significantly with hypohydration as compared to controls. The decrease was of the order of 9%, 11% and 22% in the hot dry condition and 6%, 8% and 20% in the hot humid condition with hypohydration levels of 1%, 2% and 3% respectively. The decrease was more pronounced during 3% hypohydration level under both heat stress conditions. This decrease was in spite of significant increases in maximal ventilation. However, the PWC180 under the two heat stress conditions, when compared, did not reveal any significant difference. It was concluded that the heat stress vehicle did not adversely affect the physical work capacity. On the other hand, the decreases in physical work capacity were found to be closely related to the primary hypohydration level in heat

  20. Models of Verbal Working Memory Capacity: What Does It Take to Make Them Work?

    ERIC Educational Resources Information Center

    Cowan, Nelson; Rouder, Jeffrey N.; Blume, Christopher L.; Saults, J. Scott

    2012-01-01

    Theories of working memory (WM) capacity limits will be more useful when we know what aspects of performance are governed by the limits and what aspects are governed by other memory mechanisms. Whereas considerable progress has been made on models of WM capacity limits for visual arrays of separate objects, less progress has been made in…

  1. Mild Hyperbaric Oxygen Improves Decreased Oxidative Capacity of Spinal Motoneurons Innervating the Soleus Muscle of Rats with Type 2 Diabetes.

    PubMed

    Takemura, Ai; Ishihara, Akihiko

    2016-09-01

    Rats with type 2 diabetes exhibit decreased oxidative capacity, such as reduced oxidative enzyme activity, low-intensity staining for oxidative enzymes in fibers, and no high-oxidative type IIA fibers, in the skeletal muscle, especially in the soleus muscle. In contrast, there are no data available concerning the oxidative capacity of spinal motoneurons innervating skeletal muscle of rats with type 2 diabetes. This study examined the oxidative capacity of motoneurons innervating the soleus muscle of non-obese rats with type 2 diabetes. In addition, this study examined the effects of mild hyperbaric oxygen at 1.25 atmospheres absolute with 36 % oxygen for 10 weeks on the oxidative capacity of motoneurons innervating the soleus muscle because mild hyperbaric oxygen improves the decreased oxidative capacity of the soleus muscle in non-obese rats with type 2 diabetes. Spinal motoneurons innervating the soleus muscle were identified using nuclear yellow, a retrograde fluorescent neuronal tracer. Thereafter, the cell body sizes and succinate dehydrogenase activity of identified motoneurons were analyzed. Decreased succinate dehydrogenase activity of small-sized alpha motoneurons innervating the soleus muscle was observed in rats with type 2 diabetes. The decreased succinate dehydrogenase activity of these motoneurons was improved by mild hyperbaric oxygen. Therefore, we concluded that rats with type 2 diabetes have decreased oxidative capacity in motoneurons innervating the soleus muscle and this decreased oxidative capacity is improved by mild hyperbaric oxygen. PMID:27220333

  2. Hindlimb unloading increases oxidative stress and disrupts antioxidant capacity in skeletal muscle

    NASA Technical Reports Server (NTRS)

    Lawler, John M.; Song, Wook; Demaree, Scott R.; Bloomfield, S. A. (Principal Investigator)

    2003-01-01

    Skeletal muscle disuse with space-flight and ground-based models (e.g., hindlimb unloading) results in dramatic skeletal muscle atrophy and weakness. Pathological conditions that cause muscle wasting (i.e., heart failure, muscular dystrophy, sepsis, COPD, cancer) are characterized by elevated "oxidative stress," where antioxidant defenses are overwhelmed by oxidant production. However, the existence, cellular mechanisms, and ramifications of oxidative stress in skeletal muscle subjected to hindlimb unloading are poorly understood. Thus we examined the effects of hindlimb unloading on hindlimb muscle antioxidant enzymes (e.g., superoxide dismutase, catalase, glutathione peroxidase), nonenzymatic antioxidant scavenging capacity (ASC), total hydroperoxides, and dichlorohydrofluorescein diacetate (DCFH-DA) oxidation, a direct indicator of oxidative stress. Twelve 6 month old Sprague Dawley rats were divided into two groups: 28 d of hindlimb unloading (n = 6) and controls (n = 6). Hindlimb unloading resulted in a small decrease in Mn-superoxide dismutase activity (10.1%) in the soleus muscle, while Cu,Zn-superoxide dismutase increased 71.2%. In contrast, catalase and glutathione peroxidase, antioxidant enzymes that remove hydroperoxides, were significantly reduced in the soleus with hindlimb unloading by 54.5 and 16.1%, respectively. Hindlimb unloading also significantly reduced ASC. Hindlimb unloading increased soleus lipid hydroperoxide levels by 21.6% and hindlimb muscle DCFH-DA oxidation by 162.1%. These results indicate that hindlimb unloading results in a disruption of antioxidant status, elevation of hydroperoxides, and an increase in oxidative stress.

  3. Impaired glucose metabolism and exercise capacity with muscle-specific glycogen synthase 1 (gys1) deletion in adult mice

    PubMed Central

    Xirouchaki, Chrysovalantou E.; Mangiafico, Salvatore P.; Bate, Katherine; Ruan, Zheng; Huang, Amy M.; Tedjosiswoyo, Bing Wilari; Lamont, Benjamin; Pong, Wynne; Favaloro, Jenny; Blair, Amy R.; Zajac, Jeffrey D.; Proietto, Joseph; Andrikopoulos, Sofianos

    2016-01-01

    Objective Muscle glucose storage and muscle glycogen synthase (gys1) defects have been associated with insulin resistance. As there are multiple mechanisms for insulin resistance, the specific role of glucose storage defects is not clear. The aim of this study was to examine the effects of muscle-specific gys1 deletion on glucose metabolism and exercise capacity. Methods Tamoxifen inducible and muscle specific gys-1 KO mice were generated using the Cre/loxP system. Mice were subjected to glucose tolerance tests, euglycemic/hyperinsulinemic clamps and exercise tests. Results gys1-KO mice showed ≥85% reduction in muscle gys1 mRNA and protein concentrations, 70% reduction in muscle glycogen levels, postprandial hyperglycaemia and hyperinsulinaemia and impaired glucose tolerance. Under insulin-stimulated conditions, gys1-KO mice displayed reduced glucose turnover and muscle glucose uptake, indicative of peripheral insulin resistance, as well as increased plasma and muscle lactate levels and reductions in muscle hexokinase II levels. gys1-KO mice also exhibited markedly reduced exercise and endurance capacity. Conclusions Thus, muscle-specific gys1 deletion in adult mice results in glucose intolerance due to insulin resistance and reduced muscle glucose uptake as well as impaired exercise and endurance capacity. In brief This study demonstrates why the body prioritises muscle glycogen storage over liver glycogen storage despite the critical role of the liver in supplying glucose to the brain in the fasting state and shows that glycogen deficiency results in impaired glucose metabolism and reduced exercise capacity. PMID:26977394

  4. Relationships between Lower Limb Muscle Strength and Locomotor Capacity in Children and Adolescents with Cerebral Palsy Who Walk Independently

    ERIC Educational Resources Information Center

    Ferland, Chantale; Lepage, Celine; Moffet, Helene; Maltais, Desiree B.

    2012-01-01

    This study aimed to quantify relationships between lower limb muscle strength and locomotor capacity for children and adolescents with cerebral palsy (CP) to identify key muscle groups for strength training. Fifty 6- to 16-year-olds with CP (Gross Motor Function Classification System level I or II) participated. Isometric muscle strength of hip…

  5. Working memory capacity and suppression of intrusive thoughts.

    PubMed

    Brewin, Chris R; Smart, Laura

    2005-03-01

    We sought to show that individual differences in working memory capacity are related to the ability to intentionally suppress personally relevant intrusive thoughts, and that this effect cannot be explained by differences in negative mood. Sixty participants identified their most frequent intrusive thought and then completed a thought suppression task. Better performance on a measure of working memory capacity (OSPAN) was related to having fewer intrusions in the suppression condition but was unrelated to number of intrusions in the expression condition, suggesting a specific association with attempts to inhibit unwanted thoughts. In contrast, a more negative mood was related to having more intrusions in both conditions, suggestive of a more general influence on the accessibility of unwanted thoughts. Working memory capacity was not associated with negative mood or with the frequency of intrusive thoughts reported in everyday life. The findings extend previous results to the domain of personally relevant intrusive thoughts and support the idea that individual differences in the cognitive abilities supporting inhibitory mechanisms are relevant to clinical conditions such as obsessive-compulsive disorder and posttraumatic stress disorder. PMID:15687010

  6. The neuroscience of working memory capacity and training.

    PubMed

    Constantinidis, Christos; Klingberg, Torkel

    2016-07-01

    Working memory - the ability to maintain and manipulate information over a period of seconds - is a core component of higher cognitive functions. The storage capacity of working memory is limited but can be expanded by training, and evidence of the neural mechanisms underlying this effect is accumulating. Human imaging studies and neurophysiological recordings in non-human primates, together with computational modelling studies, reveal that training increases the activity of prefrontal neurons and the strength of connectivity in the prefrontal cortex and between the prefrontal and parietal cortex. Dopaminergic transmission could have a facilitatory role. These changes more generally inform us of the plasticity of higher cognitive functions. PMID:27225070

  7. Evidence of Preserved Oxidative Capacity and Oxygen Delivery in the Plantar Flexor Muscles With Age.

    PubMed

    Hart, Corey R; Layec, Gwenael; Trinity, Joel D; Liu, Xin; Kim, Seong-Eun; Groot, H Jonathan; Le Fur, Yann; Sorensen, Jacob R; Jeong, Eun-Kee; Richardson, Russell S

    2015-09-01

    Studies examining the effect of aging on skeletal muscle oxidative capacity have yielded equivocal results; however, these investigations may have been confounded by differences in oxygen (O(2)) delivery, physical activity, and small numbers of participants. Therefore, we evaluated skeletal muscle oxidative capacity and O(2) delivery in a relatively large group (N = 40) of young (22 ± 2 years) and old (73 ± 7 years) participants matched for physical activity. After submaximal dynamic plantar flexion exercise, phosphocreatine (PCr) resynthesis ((31)P magnetic resonance spectroscopy), muscle reoxygenation (near-infrared spectroscopy), and popliteal artery blood flow (Doppler ultrasound) were measured. The phosphocreatine recovery time constant (Tau) (young: 33 ± 16; old: 30 ± 11 seconds), maximal rate of adenosine triphosphate (ATP) synthesis (young: 25 ± 9; old: 27 ± 8 mM/min), and muscle reoxygenation rates determined by the deoxyhemoglobin/myoglobin recovery Tau (young: 48 ± 5; old: 47 ± 9 seconds) were similar between groups. Similarly, although tending to be higher in the old, there were no significant age-related differences in postexercise popliteal blood flow (area under the curve: young: 1,665 ± 227 vs old: 2,404 ± 357 mL, p = .06) and convective O(2) delivery (young: 293 ± 146 vs old: 404 ± 191 mL, p = .07). In conclusion, when physical activity and O(2) delivery are similar, oxidative capacity in the plantar flexors is not affected by aging. These findings reveal that diminished skeletal muscle oxidative capacity is not an obligatory accompaniment to the aging process. PMID:25165028

  8. Working memory capacity and redundant information processing efficiency

    PubMed Central

    Endres, Michael J.; Houpt, Joseph W.; Donkin, Chris; Finn, Peter R.

    2015-01-01

    Working memory capacity (WMC) is typically measured by the amount of task-relevant information an individual can keep in mind while resisting distraction or interference from task-irrelevant information. The current research investigated the extent to which differences in WMC were associated with performance on a novel redundant memory probes (RMP) task that systematically varied the amount of to-be-remembered (targets) and to-be-ignored (distractor) information. The RMP task was designed to both facilitate and inhibit working memory search processes, as evidenced by differences in accuracy, response time, and Linear Ballistic Accumulator (LBA) model estimates of information processing efficiency. Participants (N = 170) completed standard intelligence tests and dual-span WMC tasks, along with the RMP task. As expected, accuracy, response-time, and LBA model results indicated memory search and retrieval processes were facilitated under redundant-target conditions, but also inhibited under mixed target/distractor and redundant-distractor conditions. Repeated measures analyses also indicated that, while individuals classified as high (n = 85) and low (n = 85) WMC did not differ in the magnitude of redundancy effects, groups did differ in the efficiency of memory search and retrieval processes overall. Results suggest that redundant information reliably facilitates and inhibits the efficiency or speed of working memory search, and these effects are independent of more general limits and individual differences in the capacity or space of working memory. PMID:26074828

  9. Extrapulmonary features of bronchiectasis: muscle function, exercise capacity, fatigue, and health status

    PubMed Central

    2012-01-01

    Background There are limited number of studies investigating extrapulmonary manifestations of bronchiectasis. The purpose of this study was to compare peripheral muscle function, exercise capacity, fatigue, and health status between patients with bronchiectasis and healthy subjects in order to provide documented differences in these characteristics for individuals with and without bronchiectasis. Methods Twenty patients with bronchiectasis (43.5 ± 14.1 years) and 20 healthy subjects (43.0 ± 10.9 years) participated in the study. Pulmonary function, respiratory muscle strength (maximal expiratory pressure – MIP - and maximal expiratory pressure - MEP), and dyspnea perception using the Modified Medical Research Council Dyspnea Scale (MMRC) were determined. A six-minute walk test (6MWT) was performed. Quadriceps muscle, shoulder abductor, and hand grip strength (QMS, SAS, and HGS, respectively) using a hand held dynamometer and peripheral muscle endurance by a squat test were measured. Fatigue perception and health status were determined using the Fatigue Severity Scale (FSS) and the Leicester Cough Questionnaire (LCQ), respectively. Results Number of squats, 6MWT distance, and LCQ scores as well as lung function testing values and respiratory muscle strength were significantly lower and MMRC and FSS scores were significantly higher in patients with bronchiectasis than those of healthy subjects (p < 0.05). In bronchiectasis patients, QMS was significantly associated with HGS, MIP and MEP (p < 0.05). The 6MWT distance was significantly correlated to LCQ psychological score (p < 0.05). The FSS score was significantly associated with LCQ physical and total and MMRC scores (p < 0.05). The LCQ psychological score was significantly associated with MEP and 6MWT distance (p < 0.05). Conclusions Peripheral muscle endurance, exercise capacity, fatigue and health status were adversely affected by the presence of bronchiectasis. Fatigue was associated

  10. Working with Toronto neighbourhoods toward developing indicators of community capacity.

    PubMed

    Jackson, Suzanne F; Cleverly, Shelley; Poland, Blake; Burman, David; Edwards, Richard; Robertson, Ann

    2003-12-01

    Often the goal of health and social development agencies is to assess communities and work with them to improve community capacity. Particularly for health promoters working in community settings and to ensure consistency in the definition of health promotion, the evaluation of health promotion programmes should be based on strengths and assets, yet existing information for planning and evaluation purposes usually focuses on problems and deficits. A model and definition of community capacity, grounded in community experience and focusing on strengths and assets, was developed following a 4-year, multi-site, qualitative, action research project in four Toronto neighbourhoods. There was significant community involvement in the four Community Advisory Committees, one for each study site. Semi-structured, open-ended interviews and focus groups were conducted with 161 residents and agency workers identified by the Community Advisory Committees. The data were analyzed with the assistance of NUDIST software. Thematic analysis was undertaken in two stages: (i) within each site and (ii) across sites, with the latter serving as the basis for the development of indicators of community capacity. This paper presents a summary of the research, the model and the proposed indicators. The model locates talents and skills of community members in a larger context of socioenvironmental conditions, both inside and outside the community, which can act to enable or constrain the expression of these talents and skills. The significance of the indicators of community capacity proposed in the study is that they focus on identifying and measuring the facilitating and constraining socioenvironmental conditions. PMID:14695365

  11. Abnormal skeletal muscle oxidative capacity after lung transplantation by 31P-MRS.

    PubMed

    Evans, A B; Al-Himyary, A J; Hrovat, M I; Pappagianopoulos, P; Wain, J C; Ginns, L C; Systrom, D M

    1997-02-01

    Although lung transplantation improves exercise capacity by removal of a ventilatory limitation, recipients' postoperative maximum oxygen uptake (VO2max) remains markedly abnormal. To determine if abnormal skeletal muscle oxidative capacity contributes to this impaired aerobic capacity, nine lung transplant recipients and eight healthy volunteers performed incremental quadriceps exercise to exhaustion with simultaneous measurements of pulmonary gas exchange, minute ventilation, blood lactate, and quadriceps muscle pH and phosphorylation potential by 31P-magnetic resonance spectroscopy (31P-MRS). Five to 38 mo after lung transplantation, peak VO2 was decreased compared with that of normal control subjects (6.7 +/- 0.4 versus 12.3 +/- 1.0 ml/min/kg, p < 0.001), even after accounting for differences in age and lean body weight. Neither ventilation, arterial O2 saturation nor mild anemia could account for the decrease in aerobic capacity. Quadriceps muscle intracellular pH (pH(i)) was more acidic at rest (7.07 +/- 0.01 versus 7.12 +/- 0.01 units, p < 0.05) and fell during exercise from baseline values at a lower metabolic rate (282 +/- 21 versus 577 +/- 52 ml/min, p < 0.001). Regressions for pH(i) versus VO2, phosphocreatine/inorganic phosphate ratio (PCr/Pi) versus VO2, and blood lactate versus pH(i) were not different. Among transplant recipients, the metabolic rate at which pH(i) fell correlated closely with VO2max (r = 0.87, p < 0.01). The persistent decrease in VO2max after lung transplantation may be related to abnormalities of skeletal muscle oxidative capacity. PMID:9032203

  12. [Work difficulty and the physical work capacity of female afforestation workers in forestry].

    PubMed

    Mincheva, L; Khadzhiolova, I; Dunev, S; Polianska, L

    1986-01-01

    The severity of labour in manual soil-preparation and planting has been studied and the physical capacity for work of the female workers--determined, who performed those basic afforestation activities in the national forestry. The severity of labour has been characterized by the values of oxygen consumption, energy-expenditure and pulse rate during work. The physical capacity for work has been determined by physical loading on the Lanoy bicycle ergometer , with submaximum degrees of loading. The maximum working capacity was calculated by the values of the pulse rate with submaximum degrees of loading according to Astrand method. The physical loading during manual soil-preparation is high (6.6 kcal/min, 27.6 kJ resp.), and that of planting--moderate. The maximum aerobic capacity of the afforestation female workers examined, was characterized by maximum oxygen consumption 2.04 dm3/min, 29.6 cm3/kg/min resp., and maximum pulse rate--177 beats/min. Energy losses during work surpassed, to a considerable degree, 30 per cent of the maximum aerobic capacity of the female afforestation workers. On the base of the results obtained, measures are proposed for the reduction of the severity of labour and for improvement of the organization of the work during the afforestation activities in national forestry. PMID:3823039

  13. Working Fluids for Increasing Capacities of Heat Pipes

    NASA Technical Reports Server (NTRS)

    Chao, David F.; Zhang, Nengli

    2004-01-01

    A theoretical and experimental investigation has shown that the capacities of heat pipes can be increased through suitable reformulation of their working fluids. The surface tensions of all of the working fluids heretofore used in heat pipes decrease with temperature. As explained in more detail below, the limits on the performance of a heat pipe are associated with the decrease in the surface tension of the working fluid with temperature, and so one can enhance performance by reformulating the working fluid so that its surface tension increases with temperature. This improvement is applicable to almost any kind of heat pipe in almost any environment. The heat-transfer capacity of a heat pipe in its normal operating-temperature range is subject to a capillary limit and a boiling limit. Both of these limits are associated with the temperature dependence of surface tension of the working fluid. In the case of a traditional working fluid, the decrease in surface tension with temperature causes a body of the liquid phase of the working fluid to move toward a region of lower temperature, thus preventing the desired spreading of the liquid in the heated portion of the heat pipe. As a result, the available capillary-pressure pumping head decreases as the temperature of the evaporator end of the heat pipe increases, and operation becomes unstable. Water has widely been used as a working fluid in heat pipes. Because the surface tension of water decreases with increasing temperature, the heat loads and other aspects of performance of heat pipes that contain water are limited. Dilute aqueous solutions of long-chain alcohols have shown promise as substitutes for water that can offer improved performance, because these solutions exhibit unusual surface-tension characteristics: Experiments have shown that in the cases of an aqueous solution of an alcohol, the molecules of which contain chains of more than four carbon atoms, the surface tension increases with temperature when the

  14. Seasonal cycles of mitochondrial ADP sensitivity and oxidative capacities in trout oxidative muscle.

    PubMed

    Guderley, H; St Pierre, J

    1999-10-01

    Mitochondria from red myotomal muscle of rainbow trout, Oncorhynchus mykiss, showed seasonal cycles of their maximal rates of substrate oxidation (nmol.min-1 mg-1 mitochondrial protein) and their apparent ADP affinity (Kmapp), as well as in the thermal sensitivity of these properties. Increases in the maximal capacity of pyruvate oxidation were sufficient to compensate for seasonal changes in temperature, except during the winter months when rates at habitat temperature were depressed relative to other periods. The ADP affinity of isolated mitochondria was highest during cold months. Thus, the Kmapp for ADP at habitat temperature showed less seasonal variation than the ADP Kmapp at a given temperature. A loss in ADP affinity with decreasing temperature occurred through much of the year, and only was definitively suppressed in December and July. Both the ADP affinity and the maximal oxidative capacities of muscle mitochondria seem to be regulated parameters. PMID:10595316

  15. Skeletal Muscle Mitochondrial Energetics Are Associated With Maximal Aerobic Capacity and Walking Speed in Older Adults

    PubMed Central

    2013-01-01

    Background. Lower ambulatory performance with aging may be related to a reduced oxidative capacity within skeletal muscle. This study examined the associations between skeletal muscle mitochondrial capacity and efficiency with walking performance in a group of older adults. Methods. Thirty-seven older adults (mean age 78 years; 21 men and 16 women) completed an aerobic capacity (VO2 peak) test and measurement of preferred walking speed over 400 m. Maximal coupled (State 3; St3) mitochondrial respiration was determined by high-resolution respirometry in saponin-permeabilized myofibers obtained from percutanous biopsies of vastus lateralis (n = 22). Maximal phosphorylation capacity (ATPmax) of vastus lateralis was determined in vivo by 31P magnetic resonance spectroscopy (n = 30). Quadriceps contractile volume was determined by magnetic resonance imaging. Mitochondrial efficiency (max ATP production/max O2 consumption) was characterized using ATPmax per St3 respiration (ATPmax/St3). Results. In vitro St3 respiration was significantly correlated with in vivo ATPmax (r 2 = .47, p = .004). Total oxidative capacity of the quadriceps (St3*quadriceps contractile volume) was a determinant of VO2 peak (r 2 = .33, p = .006). ATPmax (r 2 = .158, p = .03) and VO2 peak (r 2 = .475, p < .0001) were correlated with preferred walking speed. Inclusion of both ATPmax/St3 and VO2 peak in a multiple linear regression model improved the prediction of preferred walking speed (r 2 = .647, p < .0001), suggesting that mitochondrial efficiency is an important determinant for preferred walking speed. Conclusions. Lower mitochondrial capacity and efficiency were both associated with slower walking speed within a group of older participants with a wide range of function. In addition to aerobic capacity, lower mitochondrial capacity and efficiency likely play roles in slowing gait speed with age. PMID:23051977

  16. Aldehyde Dehydrogenase Activity Identifies a Population of Human Skeletal Muscle Cells With High Myogenic Capacities

    PubMed Central

    Vauchez, Karine; Marolleau, Jean-Pierre; Schmid, Michel; Khattar, Patricia; Chapel, Alain; Catelain, Cyril; Lecourt, Séverine; Larghéro, Jérôme; Fiszman, Marc; Vilquin, Jean-Thomas

    2009-01-01

    Aldehyde dehydrogenase 1A1 (ALDH) activity is one hallmark of human bone marrow (BM), umbilical cord blood (UCB), and peripheral blood (PB) primitive progenitors presenting high reconstitution capacities in vivo. In this study, we have identified ALDH+ cells within human skeletal muscles, and have analyzed their phenotypical and functional characteristics. Immunohistofluorescence analysis of human muscle tissue sections revealed rare endomysial cells. Flow cytometry analysis using the fluorescent substrate of ALDH, Aldefluor, identified brightly stained (ALDHbr) cells with low side scatter (SSClo), in enzymatically dissociated muscle biopsies, thereafter abbreviated as SMALD+ (for skeletal muscle ALDH+) cells. Phenotypical analysis discriminated two sub-populations according to CD34 expression: SMALD+/CD34− and SMALD+/CD34+ cells. These sub-populations did not initially express endothelial (CD31), hematopoietic (CD45), and myogenic (CD56) markers. Upon sorting, however, whereas SMALD+/CD34+ cells developed in vitro as a heterogeneous population of CD56− cells able to differentiate in adipoblasts, the SMALD+/CD34− fraction developed in vitro as a highly enriched population of CD56+ myoblasts able to form myotubes. Moreover, only the SMALD+/CD34− population maintained a strong myogenic potential in vivo upon intramuscular transplantation. Our results suggest that ALDH activity is a novel marker for a population of new human skeletal muscle progenitors presenting a potential for cell biology and cell therapy. PMID:19738599

  17. A Geometric Capacity-Demand Analysis of Maternal Levator Muscle Stretch Required for Vaginal Delivery.

    PubMed

    Tracy, Paige V; DeLancey, John O; Ashton-Miller, James A

    2016-02-01

    Because levator ani (LA) muscle injuries occur in approximately 13% of all vaginal births, insights are needed to better prevent them. In Part I of this paper, we conducted an analysis of the bony and soft tissue factors contributing to the geometric "capacity" of the maternal pelvis and pelvic floor to deliver a fetal head without incurring stretch injury of the maternal soft tissue. In Part II, we quantified the range in demand, represented by the variation in fetal head size and shape, placed on the maternal pelvic floor. In Part III, we analyzed the capacity-to-demand geometric ratio, g, in order to determine whether a mother can deliver a head of given size without stretch injury. The results of a Part I sensitivity analysis showed that initial soft tissue loop length (SL) had the greatest effect on maternal capacity, followed by the length of the soft tissue loop above the inferior pubic rami at ultimate crowning, then subpubic arch angle (SPAA) and head size, and finally the levator origin separation distance. We found the more caudal origin of the puborectal portion of the levator muscle helps to protect it from the stretch injuries commonly observed in the pubovisceral portion. Part II fetal head molding index (MI) and fetal head size revealed fetal head circumference values ranging from 253 to 351 mm, which would increase up to 11 mm upon face presentation. The Part III capacity-demand analysis of g revealed that, based on geometry alone, the 10th percentile maternal capacity predicted injury for all head sizes, the 25th percentile maternal capacity could deliver half of all head sizes, while the 50th percentile maternal capacity could deliver a head of any size without injury. If ultrasound imaging could be operationalized to make measurements of ratio g, it might be used to usefully inform women on their level of risk for levator injury during vaginal birth. PMID:26746116

  18. Working memory capacity and categorization: individual differences and modeling.

    PubMed

    Lewandowsky, Stephan

    2011-05-01

    Working memory is crucial for many higher-level cognitive functions, ranging from mental arithmetic to reasoning and problem solving. Likewise, the ability to learn and categorize novel concepts forms an indispensable part of human cognition. However, very little is known about the relationship between working memory and categorization, and modeling in category learning has thus far been largely uninformed by knowledge about people's memory processes. This article reports a large study (N = 113) that related people's working memory capacity (WMC) to their category-learning performance using the 6 problem types of Shepard, Hovland, and Jenkins (1961). Structural equation modeling revealed a strong relationship between WMC and category learning, with a single latent variable accommodating performance on all 6 problems. A model of categorization (the Attention Learning COVEring map, ALCOVE; Kruschke, 1992) was fit to the individual data and a single latent variable was sufficient to capture the variation among associative learning parameters across all problems. The data and modeling suggest that working memory mediates category learning across a broad range of tasks. PMID:21417512

  19. Rats Bred for Low Aerobic Capacity Become Promptly Fatigued and Have Slow Metabolic Recovery after Stimulated, Maximal Muscle Contractions

    PubMed Central

    Torvinen, Sira; Silvennoinen, Mika; Piitulainen, Harri; Närväinen, Johanna; Tuunanen, Pasi; Gröhn, Olli; Koch, Lauren G.; Britton, Steven L.; Kainulainen, Heikki

    2012-01-01

    AIM Muscular fatigue is a complex phenomenon affected by muscle fiber type and several metabolic and ionic changes within myocytes. Mitochondria are the main determinants of muscle oxidative capacity which is also one determinant of muscle fatigability. By measuring the concentrations of intracellular stores of high-energy phosphates it is possible to estimate the energy production efficiency and metabolic recovery of the muscle. Low intrinsic aerobic capacity is known to be associated with reduced mitochondrial function. Whether low intrinsic aerobic capacity also results in slower metabolic recovery of skeletal muscle is not known. Here we studied the influence of intrinsic aerobic capacity on in vivo muscle metabolism during maximal, fatiguing electrical stimulation. METHODS Animal subjects were genetically heterogeneous rats selectively bred to differ for non–trained treadmill running endurance, low capacity runners (LCRs) and high capacity runners (HCRs) (n = 15–19). We measured the concentrations of major phosphorus compounds and force parameters in a contracting triceps surae muscle complex using 31P-Magnetic resonance spectroscopy (31P-MRS) combined with muscle force measurement from repeated isometric twitches. RESULTS Our results demonstrated that phosphocreatine re-synthesis after maximal muscle stimulation was significantly slower in LCRs (p<0.05). LCR rats also became promptly fatigued and maintained the intramuscular pH poorly compared to HCRs. Half relaxation time (HRT) of the triceps surae was significantly longer in LCRs throughout the stimulation protocol (p≤0.05) and maximal rate of torque development (MRTD) was significantly lower in LCRs compared to HCRs from 2 min 30 s onwards (p≤0.05). CONCLUSION We observed that LCRs are more sensitive to fatigue and have slower metabolic recovery compared to HCRs after maximal muscle contractions. These new findings are associated with reduced running capacity and with previously found lower

  20. Working memory capacity predicts conflict-task performance.

    PubMed

    Gulbinaite, Rasa; Johnson, Addie

    2014-01-01

    The relationship between the ability to maintain task goals and working memory capacity (WMC) is firmly established, but evidence for WMC-related differences in conflict processing is mixed. We investigated whether WMC (measured using two complex-span tasks) mediates differences in adjustments of cognitive control in response to conflict. Participants performed a Simon task in which congruent and incongruent trials were equiprobable, but in which the proportion of congruency repetitions (congruent trials followed by congruent trials or incongruent trials followed by incongruent trials) and thus the need for trial-by-trial adjustments in cognitive control varied by block. The overall Simon effect did not depend on WMC capacity. However, for the low-WMC participants the Simon effect decreased as the proportion of congruency repetitions decreased, whereas for the high- and average-WMC participants it was relatively constant across conditions. Distribution analysis of the Simon effect showed more evidence for the inhibition of stimulus location in the low- than in the high-WMC participants, especially when the proportion of congruency repetitions was low. We hypothesize that low-WMC individuals exhibit more interference from task-irrelevant information due to weaker preparatory control prior to stimulus presentation and, thus, stronger reliance on reactive recruitment of cognitive control. PMID:24199908

  1. Working memory capacity and controlled serial memory search.

    PubMed

    Mızrak, Eda; Öztekin, Ilke

    2016-08-01

    The speed-accuracy trade-off (SAT) procedure was used to investigate the relationship between working memory capacity (WMC) and the dynamics of temporal order memory retrieval. High- and low-span participants (HSs, LSs) studied sequentially presented five-item lists, followed by two probes from the study list. Participants indicated the more recent probe. Overall, accuracy was higher for HSs compared to LSs. Crucially, in contrast to previous investigations that observed no impact of WMC on speed of access to item information in memory (e.g., Öztekin & McElree, 2010), recovery of temporal order memory was slower for LSs. While accessing an item's representation in memory can be direct, recovery of relational information such as temporal order information requires a more controlled serial memory search. Collectively, these data indicate that WMC effects are particularly prominent during high demands of cognitive control, such as serial search operations necessary to access temporal order information from memory. PMID:27135712

  2. Working memory capacity, controlled attention and aiming performance under pressure.

    PubMed

    Wood, Greg; Vine, Samuel J; Wilson, Mark R

    2016-07-01

    This study explored the possibility that individual differences in working memory capacity (WMC) could predict those individuals who would experience attentional disruptions and performance decrements under pressure. Two WMC groups performed a Stroop handgun task under counterbalanced conditions of threat whilst wearing eye-tracking equipment that measured visual search activity and quiet eye (QE) aiming duration. Performance was measured in terms of shooting accuracy. Low-WMC individuals experienced impaired visual search time to locate the target and reduced QE durations when shooting at incongruent target words. Furthermore, the low-WMC group experienced significant reductions in shooting accuracy when anxious. Conversely, high-WMC individuals experienced no significant differences in attentional control or performance across congruency or threat conditions. Results support the suggestion that WMC is not only a good predictor of an individual's ability to control their attention but can also predict those likely to fail under pressure. PMID:26021749

  3. Working Memory Capacity Predicts Effects of Methylphenidate on Reversal Learning

    PubMed Central

    van der Schaaf, Marieke E; Fallon, Sean J; ter Huurne, Niels; Buitelaar, Jan; Cools, Roshan

    2013-01-01

    Increased use of stimulant medication, such as methylphenidate, by healthy college students has raised questions about its cognitive-enhancing effects. Methylphenidate acts by increasing extracellular catecholamine levels and is generally accepted to remediate cognitive and reward deficits in patients with attention deficit hyperactivity disorder. However, the cognitive-enhancing effects of such ‘smart drugs' in the healthy population are still unclear. Here, we investigated effects of methylphenidate (Ritalin, 20 mg) on reward and punishment learning in healthy students (N=19) in a within-subject, double-blind, placebo-controlled cross-over design. Results revealed that methylphenidate effects varied both as a function of task demands and as a function of baseline working memory capacity. Specifically, methylphenidate improved reward vs punishment learning in high-working memory subjects, whereas it impaired reward vs punishment learning in low-working memory subjects. These results contribute to our understanding of individual differences in the cognitive-enhancing effects of methylphenidate in the healthy population. Moreover, they highlight the importance of taking into account both inter- and intra-individual differences in dopaminergic drug research. PMID:23612436

  4. Emotional working memory capacity in posttraumatic stress disorder (PTSD).

    PubMed

    Schweizer, Susanne; Dalgleish, Tim

    2011-08-01

    Participants with a lifetime history of posttraumatic stress disorder (PTSD) and trauma-exposed controls with no PTSD history completed an emotional working memory capacity (eWMC) task. The task required them to remember lists of neutral words over short intervals while simultaneously processing sentences describing dysfunctional trauma-related thoughts (relative to neutral control sentences). The task was designed to operationalise an everyday cognitive challenge for those with mental health problems such as PTSD; namely, the ability to carry out simple, routine tasks with emotionally benign material, while at the same time tackling emotional laden intrusive thoughts and feelings. eWMC performance, indexed as the ability to remember the word lists in the context of trauma sentences, relative to neutral sentences, was poorer overall in the PTSD group compared with controls, suggestive of a particular difficulty employing working memory in emotion-related contexts in those with a history of PTSD. The possible implications for developing affective working memory training as an adjunctive treatment for PTSD are explored. PMID:21684525

  5. Physical Workload and Work Capacity across Occupational Groups

    PubMed Central

    Brighenti-Zogg, Stefanie; Mundwiler, Jonas; Schüpbach, Ulla; Dieterle, Thomas; Wolfer, David Paul; Leuppi, Jörg Daniel; Miedinger, David

    2016-01-01

    This study aimed to determine physical performance criteria of different occupational groups by investigating physical activity and energy expenditure in healthy Swiss employees in real-life workplaces on workdays and non-working days in relation to their aerobic capacity (VO2max). In this cross-sectional study, 337 healthy and full-time employed adults were recruited. Participants were classified (nine categories) according to the International Standard Classification of Occupations 1988 and merged into three groups with low-, moderate- and high-intensity occupational activity. Daily steps, energy expenditure, metabolic equivalents and activity at different intensities were measured using the SenseWear Mini armband on seven consecutive days (23 hours/day). VO2max was determined by the 20-meter shuttle run test. Data of 303 subjects were considered for analysis (63% male, mean age: 33 yrs, SD 12), 101 from the low-, 102 from the moderate- and 100 from the high-intensity group. At work, the high-intensity group showed higher energy expenditure, metabolic equivalents, steps and activity at all intensities than the other groups (p<0.001). There were no significant differences in physical activity between the occupational groups on non-working days. VO2max did not differ across groups when stratified for gender. The upper workload limit was 21%, 29% and 44% of VO2max in the low-, moderate- and high-intensity group, respectively. Men had a lower limit than women due to their higher VO2max (26% vs. 37%), when all groups were combined. While this study did confirm that the average workload limit is one third of VO2max, it showed that the average is misrepresenting the actual physical work demands of specific occupational groups, and that it does not account for gender-related differences in relative workload. Therefore, clinical practice needs to consider these differences with regard to a safe return to work, particularly for the high-intensity group. PMID:27136206

  6. Physical Workload and Work Capacity across Occupational Groups.

    PubMed

    Brighenti-Zogg, Stefanie; Mundwiler, Jonas; Schüpbach, Ulla; Dieterle, Thomas; Wolfer, David Paul; Leuppi, Jörg Daniel; Miedinger, David

    2016-01-01

    This study aimed to determine physical performance criteria of different occupational groups by investigating physical activity and energy expenditure in healthy Swiss employees in real-life workplaces on workdays and non-working days in relation to their aerobic capacity (VO2max). In this cross-sectional study, 337 healthy and full-time employed adults were recruited. Participants were classified (nine categories) according to the International Standard Classification of Occupations 1988 and merged into three groups with low-, moderate- and high-intensity occupational activity. Daily steps, energy expenditure, metabolic equivalents and activity at different intensities were measured using the SenseWear Mini armband on seven consecutive days (23 hours/day). VO2max was determined by the 20-meter shuttle run test. Data of 303 subjects were considered for analysis (63% male, mean age: 33 yrs, SD 12), 101 from the low-, 102 from the moderate- and 100 from the high-intensity group. At work, the high-intensity group showed higher energy expenditure, metabolic equivalents, steps and activity at all intensities than the other groups (p<0.001). There were no significant differences in physical activity between the occupational groups on non-working days. VO2max did not differ across groups when stratified for gender. The upper workload limit was 21%, 29% and 44% of VO2max in the low-, moderate- and high-intensity group, respectively. Men had a lower limit than women due to their higher VO2max (26% vs. 37%), when all groups were combined. While this study did confirm that the average workload limit is one third of VO2max, it showed that the average is misrepresenting the actual physical work demands of specific occupational groups, and that it does not account for gender-related differences in relative workload. Therefore, clinical practice needs to consider these differences with regard to a safe return to work, particularly for the high-intensity group. PMID:27136206

  7. A Probabilistic Model of Visual Working Memory: Incorporating Higher Order Regularities into Working Memory Capacity Estimates

    ERIC Educational Resources Information Center

    Brady, Timothy F.; Tenenbaum, Joshua B.

    2013-01-01

    When remembering a real-world scene, people encode both detailed information about specific objects and higher order information like the overall gist of the scene. However, formal models of change detection, like those used to estimate visual working memory capacity, assume observers encode only a simple memory representation that includes no…

  8. Actovegin, a non-prohibited drug increases oxidative capacity in human skeletal muscle.

    PubMed

    Søndergård, Stine D; Dela, Flemming; Helge, Jørn W; Larsen, Steen

    2016-10-01

    Actovegin, a deproteinized haemodialysate of calf blood, is suggested to have ergogenic properties, but this potential effect has never been investigated in human skeletal muscle. To investigate this purported ergogenic effect, we measured the mitochondrial respiratory capacity in permeabilized human skeletal muscle fibres acutely exposed to Actovegin in a low and in a high dose. We found that Actovegin, in the presence of complex I-linked substrates increased the oxidative phosphorylation (OXPHOS) capacity significantly in a concentration-dependent manner (19 ± 3, 31 ± 4 and 45 ± 4 pmol/mg/s). Maximal OXPHOS capacity with complex I and II-linked substrate was increased when the fibres were exposed to the high dose of Actovegin (62 ± 6 and 77 ± 6 pmol/mg/s) (p < .05). The respiratory capacity of the electron transfer system as well as Vmax and Km were also increased in a concentration-dependent manner after Actovegin exposure (70 ± 6, 79 ± 6 and 88 ± 7 pmol/mg/s; 13 ± 2, 25 ± 3 and 37 ± 4 pmol/mg/s; 0.08 ± 0.02, 0.21 ± 0.03 and 0.36 ± 0.03 mM, respectively) (p < .05). In summary, we report for the first time that Actovegin has a marked effect on mitochondrial oxidative function in human skeletal muscle. Mitochondrial adaptations like this are also seen after a training program in human subjects. Whether this improvement translates into an ergogenic effect in athletes and thus reiterates the need to include Actovegin on the World Anti-Doping Agency's active list remains to be investigated. PMID:26744809

  9. [Effect of exhaustive weightlifting exercise on EMG, biochemical markers of muscle damage and performance capacity in young male subjects].

    PubMed

    Minigalin, A D; Shumakov, A R; Novozhilov, A V; Samsonova, A V; Kos'mina, E A; Kalinskiĭ, M I; Baranova, T I; Kubasov, I V; Morozov, V I

    2015-01-01

    The aim of this study was to examine the effect of exhaustive weightlifting exercise on electrical and biochemical variables and performance capacity in young male subjects. The onset of exercise (80-50% 1RM) was associated with a decrease in the amount of work performed, which was followed by a steady performance capacity at 40-10% 1RM. There were no significant changes of m. rectus femoris EMG maximal amplitude though it tended to be increased during the first half of exercise. A significant blood lactate concentration increase indicated that an anaerobic metabolism was a predominant mechanism of muscle contraction energy-supply. CK level in blood plasma did not change but plasma myoglobin concentration doubled immediately post-exercise. The data presented here suggest that decrease in performance capacity was likely due to progressive "refusal of work" of the fast motor units and work prolongation of weaker, intermediate and slow motor units. Unchangeable CK activity and relatively small increase in myoglobin concentration in plasma suggest that used weightlifting exercise did not induced substantial damage in myocytes' membranes in our subjects. PMID:25857182

  10. Local capillary supply in muscle is not determined by local oxidative capacity.

    PubMed

    Bosutti, Alessandra; Egginton, Stuart; Barnouin, Yoann; Ganse, Bergita; Rittweger, Jörn; Degens, Hans

    2015-11-01

    It is thought that the prime determinant of global muscle capillary density is the mean oxidative capacity. However, feedback control during maturational growth or adaptive remodelling of local muscle capillarisation is likely to be more complex than simply matching O2 supply and demand in response to integrated tissue function. We tested the hypothesis that the maximal oxygen consumption (MO2,max) supported by a capillary is relatively constant, and independent of the volume of tissue supplied (capillary domain). We demonstrate that local MO2,max assessed by succinate dehydrogenase histochemistry: (1) varied more than 100-fold between individual capillaries and (2) was positively correlated to capillary domain area in both human vastus lateralis (R=0.750, P<0.001) and soleus (R=0.697, P<0.001) muscles. This suggests that, in contrast to common assumptions, capillarisation is not primarily dictated by local oxidative capacity, but rather by factors such as fibre size, or consequences of differences in fibre size such as substrate delivery and metabolite removal. PMID:26385326

  11. Models of Verbal Working Memory Capacity: What Does It Take to Make Them Work?

    PubMed Central

    Cowan, Nelson; Rouder, Jeffrey N.; Blume, Christopher L.; Saults, J. Scott

    2013-01-01

    Theories of working memory (WM) capacity limits will be more useful when we know what aspects of performance are governed by the limits and what aspects are governed by other memory mechanisms. Whereas considerable progress has been made on models of WM capacity limits for visual arrays of separate objects, less progress has been made in understanding verbal materials, especially when words are mentally combined to form multi-word units or chunks. Toward a more comprehensive theory of capacity limits, we examine models of forced-choice recognition of words within printed lists, using materials designed to produce multi-word chunks in memory (e.g., leather brief case). Several simple models were tested against data from a variety of list lengths and potential chunk sizes, with test conditions that only imperfectly elicited the inter-word associations. According to the most successful model, participants retained about 3 chunks on average in a capacity-limited region of WM, with some chunks being only subsets of the presented associative information (e.g., leather brief case retained with leather as one chunk and brief case as another). The addition to the model of an activated long-term memory (LTM) component unlimited in capacity was needed. A fixed capacity limit appears critical to account for immediate verbal recognition and other forms of WM. We advance a model-based approach that allows capacity to be assessed despite other important processing contributions. Starting with a psychological-process model of WM capacity developed to understand visual arrays, we arrive at a more unified and complete model. PMID:22486726

  12. Marination effects on water states and water-holding capacity of broiler pectoralis major muscle with different color lightness

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A total of four experiments were carried out to investigate the effect of marination on water states and water-holding capacity (WHC) of broiler pectoralis (p.) major muscle selected based on raw muscle color lightness. Boneless, skinless p. major were collected at 6-8 h postmortem from deboning li...

  13. Paternal reproductive strategy influences metabolic capacities and muscle development of Atlantic salmon (Salmo salar L.) embryos.

    PubMed

    Morasse, Sébastien; Guderley, Helga; Dodson, Julian J

    2008-01-01

    Male Atlantic salmon follow a conditional strategy, becoming either "combatants" that undertake a seaward migration and spend at least a year at sea or "sneakers" that remain in freshwater and mature as parr. A variety of physiological indices showed significant but small differences between the offspring of males that use these two reproductive tactics. Offspring fathered by anadromous male Atlantic salmon (Salmo salar L.) showed greater muscular development and muscle metabolic capacities but lower spontaneous movements than those fathered by mature male parr. At hatch and at maximum attainable wet weight (MAWW), offspring fathered by anadromous males had higher activities of mitochondrial (cytochrome C oxidase and citrate synthase) and glycolytic (lactate dehydrogenase [LDH]) enzymes than progeny of mature male parr. Enzymatic profiles of progeny of anadromous fathers also suggested greater nitrogen excretion capacity (glutamate dehydrogenase) and increased muscular development (creatine kinase and LDH) than in the progeny of mature parr. At MAWW, juveniles fathered by mature parr made considerably more spontaneous movements, presumably increasing their energy expenditures. For juveniles fathered by anadromous males, total cross-sectional areas of white and red muscle at hatch were higher due to the greater number of large-diameter fibers. We suggest that the slightly lower metabolic capacities and muscular development of alevins fathered by mature parr could reflect differences in energy partitioning during their dependence on vitellus. Greater spontaneous movements of offspring of mature male parr could favor feeding and growth after the resorption of the vitellus. PMID:18537471

  14. Mitochondrial uncoupling reduces exercise capacity despite several skeletal muscle metabolic adaptations.

    PubMed

    Schlagowski, A I; Singh, F; Charles, A L; Gali Ramamoorthy, T; Favret, F; Piquard, F; Geny, B; Zoll, J

    2014-02-15

    The effects of mitochondrial uncoupling on skeletal muscle mitochondrial adaptation and maximal exercise capacity are unknown. In this study, rats were divided into a control group (CTL, n = 8) and a group treated with 2,4-dinitrophenol, a mitochondrial uncoupler, for 28 days (DNP, 30 mg·kg(-1)·day(-1) in drinking water, n = 8). The DNP group had a significantly lower body mass (P < 0.05) and a higher resting oxygen uptake (Vo2, P < 0.005). The incremental treadmill test showed that maximal running speed and running economy (P < 0.01) were impaired but that maximal Vo2 (Vo2max) was higher in the DNP-treated rats (P < 0.05). In skinned gastrocnemius fibers, basal respiration (V0) was higher (P < 0.01) in the DNP-treated animals, whereas the acceptor control ratio (ACR, Vmax/V0) was significantly lower (P < 0.05), indicating a reduction in OXPHOS efficiency. In skeletal muscle, DNP activated the mitochondrial biogenesis pathway, as indicated by changes in the mRNA expression of PGC1-α and -β, NRF-1 and -2, and TFAM, and increased the mRNA expression of cytochrome oxidase 1 (P < 0.01). The expression of two mitochondrial proteins (prohibitin and Ndufs 3) was higher after DNP treatment. Mitochondrial fission 1 protein (Fis-1) was increased in the DNP group (P < 0.01), but mitofusin-1 and -2 were unchanged. Histochemical staining for NADH dehydrogenase and succinate dehydrogenase activity in the gastrocnemius muscle revealed an increase in the proportion of oxidative fibers after DNP treatment. Our study shows that mitochondrial uncoupling induces several skeletal muscle adaptations, highlighting the role of mitochondrial coupling as a critical factor for maximal exercise capacities. These results emphasize the importance of investigating the qualitative aspects of mitochondrial function in addition to the amount of mitochondria. PMID:24336883

  15. Analysis of Skeletal Muscle Torque Capacity and Circulating Ceramides in Patients with Advanced Heart Failure

    PubMed Central

    Brunjes, Danielle L.; Dunlop, Mark; Wu, Christina; Jones, Meaghan; Kato, Tomoko S.; Kennel, Peter J.; Armstrong, Hilary F.; Choo, Tse-Hwei; Bartels, Matthew N.; Forman, Daniel E.; Mancini, Donna M.; Schulze, P. Christian

    2016-01-01

    Background Heart failure (HF)-related exercise intolerance is thought to be perpetuated by peripheral skeletal muscle functional, structural, and metabolic abnormalities. We analyzed specific dynamics of muscle contraction in patients with HF compared with healthy, sedentary controls. Methods Isometric and isokinetic muscle parameters were measured in the dominant upper and lower limbs of 45 HF patients and 15 healthy age-matched controls. Measurements included peak torque normalized to body weight, work normalized to body weight, power, time to peak torque, and acceleration and deceleration to maximum strength times. Body morphometry (dual energy X-ray absorptiometry scan) and circulating fatty acids and ceramides (lipodomics) were analyzed in a subset of subjects (18 HF and 9 controls). Results Extension and flexion time-to-peak torque was longer in the lower limbs of HF patients. Furthermore, acceleration and deceleration times in the lower limbs were also prolonged in HF subjects. HF subjects had increased adiposity and decreased lean muscle mass compared with controls. Decreased circulating unsaturated fatty acids and increased ceramides were found in subjects with HF. Conclusions Delayed torque development suggests skeletal muscle impairments that may reflect abnormal neuromuscular functional coupling. These impairments may be further compounded by increased adiposity and inflammation associated with increased ceramides. PMID:26879888

  16. The cost of muscle power production: muscle oxygen consumption per unit work increases at low temperatures in Xenopus laevis.

    PubMed

    Seebacher, Frank; Tallis, Jason A; James, Rob S

    2014-06-01

    Metabolic energy (ATP) supply to muscle is essential to support activity and behaviour. It is expected, therefore, that there is strong selection to maximise muscle power output for a given rate of ATP use. However, the viscosity and stiffness of muscle increases with a decrease in temperature, which means that more ATP may be required to achieve a given work output. Here, we tested the hypothesis that ATP use increases at lower temperatures for a given power output in Xenopus laevis. To account for temperature variation at different time scales, we considered the interaction between acclimation for 4 weeks (to 15 or 25°C) and acute exposure to these temperatures. Cold-acclimated frogs had greater sprint speed at 15°C than warm-acclimated animals. However, acclimation temperature did not affect isolated gastrocnemius muscle biomechanics. Isolated muscle produced greater tetanus force, and faster isometric force generation and relaxation, and generated more work loop power at 25°C than at 15°C acute test temperature. Oxygen consumption of isolated muscle at rest did not change with test temperature, but oxygen consumption while muscle was performing work was significantly higher at 15°C than at 25°C, regardless of acclimation conditions. Muscle therefore consumed significantly more oxygen at 15°C for a given work output than at 25°C, and plastic responses did not modify this thermodynamic effect. The metabolic cost of muscle performance and activity therefore increased with a decrease in temperature. To maintain activity across a range of temperature, animals must increase ATP production or face an allocation trade-off at lower temperatures. Our data demonstrate the potential energetic benefits of warming up muscle before activity, which is seen in diverse groups of animals such as bees, which warm flight muscle before take-off, and humans performing warm ups before exercise. PMID:24625645

  17. Enhanced exercise and regenerative capacity in a mouse model that violates size constraints of oxidative muscle fibres

    PubMed Central

    Omairi, Saleh; Matsakas, Antonios; Degens, Hans; Kretz, Oliver; Hansson, Kenth-Arne; Solbrå, Andreas Våvang; Bruusgaard, Jo C; Joch, Barbara; Sartori, Roberta; Giallourou, Natasa; Mitchell, Robert; Collins-Hooper, Henry; Foster, Keith; Pasternack, Arja; Ritvos, Olli; Sandri, Marco; Narkar, Vihang; Swann, Jonathan R; Huber, Tobias B; Patel, Ketan

    2016-01-01

    A central tenet of skeletal muscle biology is the existence of an inverse relationship between the oxidative fibre capacity and its size. However, robustness of this relationship is unknown. We show that superimposition of Estrogen-related receptor gamma (Errγ) on the myostatin (Mtn) mouse null background (Mtn-/-/ErrγTg/+) results in hypertrophic muscle with a high oxidative capacity thus violating the inverse relationship between fibre size and oxidative capacity. We also examined the canonical view that oxidative muscle phenotype positively correlate with Satellite cell number, the resident stem cells of skeletal muscle. Surprisingly, hypertrophic fibres from Mtn-/-/ErrγTg/+ mouse showed satellite cell deficit which unexpectedly did not affect muscle regeneration. These observations 1) challenge the concept of a constraint between fibre size and oxidative capacity and 2) indicate the important role of the microcirculation in the regenerative capacity of a muscle even when satellite cell numbers are reduced. DOI: http://dx.doi.org/10.7554/eLife.16940.001 PMID:27494364

  18. Exercise training and work task induced metabolic and stress-related mRNA and protein responses in myalgic muscles.

    PubMed

    Sjøgaard, Gisela; Zebis, Mette K; Kiilerich, Kristian; Saltin, Bengt; Pilegaard, Henriette

    2013-01-01

    The aim was to assess mRNA and/or protein levels of heat shock proteins, cytokines, growth regulating, and metabolic proteins in myalgic muscle at rest and in response to work tasks and prolonged exercise training. A randomized controlled trial included 28 females with trapezius myalgia and 16 healthy controls. Those with myalgia performed ~7 hrs repetitive stressful work and were subsequently randomized to 10 weeks of specific strength training, general fitness training, or reference intervention. Muscles biopsies were taken from the trapezius muscle at baseline, after work and after 10 weeks intervention. The main findings are that the capacity of carbohydrate oxidation was reduced in myalgic compared with healthy muscle. Repetitive stressful work increased mRNA content for heat shock proteins and decreased levels of key regulators for growth and oxidative metabolism. In contrast, prolonged general fitness as well as specific strength training decreased mRNA content of heat shock protein while the capacity of carbohydrate oxidation was increased only after specific strength training. PMID:23509827

  19. Effects of voluntary activity and genetic selection on muscle metabolic capacities in house mice Mus domesticus.

    PubMed

    Houle-Leroy, P; Garland, T; Swallow, J G; Guderley, H

    2000-10-01

    Selective breeding is an important tool in behavioral genetics and evolutionary physiology, but it has rarely been applied to the study of exercise physiology. We are using artificial selection for increased wheel-running behavior to study the correlated evolution of locomotor activity and physiological determinants of exercise capacity in house mice. We studied enzyme activities and their response to voluntary wheel running in mixed hindlimb muscles of mice from generation 14, at which time individuals from selected lines ran more than twice as many revolutions per day as those from control (unselected) lines. Beginning at weaning and for 8 wk, we housed mice from each of four replicate selected lines and four replicate control lines with access to wheels that were free to rotate (wheel-access group) or locked (sedentary group). Among sedentary animals, mice from selected lines did not exhibit a general increase in aerobic capacities: no mitochondrial [except pyruvate dehydrogenase (PDH)] or glycolytic enzyme activity was significantly (P < 0.05) higher than in control mice. Sedentary mice from the selected lines exhibited a trend for higher muscle aerobic capacities, as indicated by higher levels of mitochondrial (cytochrome-c oxidase, carnitine palmitoyltransferase, citrate synthase, and PDH) and glycolytic (hexokinase and phosphofructokinase) enzymes, with concomitant lower anaerobic capacities, as indicated by lactate dehydrogenase (especially in male mice). Consistent with previous studies of endurance training in rats via voluntary wheel running or forced treadmill exercise, cytochrome-c oxidase, citrate synthase, and carnitine palmitoyltransferase activity increased in the wheel-access groups for both genders; hexokinase also increased in both genders. Some enzymes showed gender-specific responses: PDH and lactate dehydrogenase increased in wheel-access male but not female mice, and glycogen phosphorylase decreased in female but not in male mice. Two

  20. Age-dependent capacity to accelerate protein synthesis dictates the extent of compensatory growth in skeletal muscle following undernutrition

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In both humans and animals, impaired growth during early life compromises adult lean body mass and muscle strength despite skeletal muscle’s large regenerative capacity. To identify the significance of developmental age on skeletal muscle’s capacity for catch-up growth following an episode of under ...

  1. Capacity Development for Education Systems in Fragile Contexts. Working Paper

    ERIC Educational Resources Information Center

    Davies, Lynn

    2009-01-01

    This paper examines fragility, capacity development and education and the links between these by analysing relevant research and policy literature. It proposes ways forward for action and reflection at national, regional and international levels. An important element of capacity development in education systems is the establishment of education…

  2. Resistance exercise training and in vitro skeletal muscle oxidative capacity in older adults.

    PubMed

    Flack, Kyle D; Davy, Brenda M; DeBerardinis, Martin; Boutagy, Nabil E; McMillan, Ryan P; Hulver, Matthew W; Frisard, Madlyn I; Anderson, Angela S; Savla, Jyoti; Davy, Kevin P

    2016-07-01

    Whether resistance exercise training (RET) improves skeletal muscle substrate oxidative capacity and reduces mitochondrial production of reactive oxygen species in older adults remains unclear. To address this, 19 older males (≥60 years) were randomized to a RET (n = 11) or to a waitlist control group (n = 8) that remained sedentary for 12 weeks. RET was comprised of three upper body and four lower body movements on resistance machines. One set of 8-12 repetitions to failure of each movement was performed on three nonconsecutive days/week. Improvements in chest press and leg press strength were assessed using a three-repetition maximum (3 RM). Body composition was assessed via dual energy X-ray absorptiometry. Muscle biopsies were obtained from the vastus lateralis muscle at baseline and at both 3 weeks and 12 weeks. Palmitate and pyruvate oxidation rates were measured from the (14)CO2 produced from [1-(14)C] palmitic acid and [U-(14)C] pyruvate, respectively, during incubation of muscle homogenates. PGC-1α, TFAM, and PPARδ levels were quantified using qRT-PCR Citrate synthase (CS) and β-HAD activities were determined spectrophotometrically. Mitochondrial production of reactive oxygen species (ROS) were assessed using the Amplex Red Hydrogen Peroxide/Peroxidase assay. There were no significant changes in body weight or body composition following the intervention. Chest press and leg press strength (3RM) increased ~34% (both P < 0.01) with RET There were no significant changes in pyruvate or fatty acid oxidation or in the expression of target genes with the intervention. There was a modest increase (P < 0.05) in βHAD activity with RET at 12 weeks but the change in CS enzyme activity was not significant. In addition, there were no significant changes in ROS production in either group following RET Taken together, the findings of this study suggest that 12 weeks of low volume RET does not increase skeletal muscle oxidative capacity or reduce ROS

  3. Vital capacity, respiratory muscle strength, and pulmonary gas exchange during long-duration exposure to microgravity.

    PubMed

    Prisk, G Kim; Fine, Janelle M; Cooper, Trevor K; West, John B

    2006-08-01

    Extended exposure to microgravity (microG) is known to reduce strength in weight-bearing muscles and was also reported to reduce respiratory muscle strength. Short- duration exposure to microG reduces vital capacity (VC), a surrogate measure for respiratory muscle strength, for the first few days, with little change in O2 uptake, ventilation, or end-tidal partial pressures. Accordingly we measured VC, maximum inspiratory and expiratory pressures, and indexes of pulmonary gas exchange in 10 normal subjects (9 men, 1 woman, 39-52 yr) who lived on the International Space Station for 130-196 days in a normoxic, normobaric atmosphere. Subjects were studied four times in the standing and supine postures preflight at sea level at 1 G, approximately monthly in microG, and multiple times postflight. VC in microG was essentially unchanged compared with preflight standing [5.28 +/- 0.08 liters (mean +/- SE), n = 187; 5.24 +/- 0.09, n = 117, respectively; P = 0.03] and considerably greater than that measured supine in 1G (4.96 +/- 0.10, n = 114, P < 0.001). There was a trend for VC to decrease after the first 2 mo of microG, but there were no changes postflight. Maximum respiratory pressures in microG were generally intermediate to those standing and supine in 1G, and importantly they showed no decrease with time spent in microG. O2 uptake and CO2 production were reduced (approximately 12%) in extended microG, but inhomogeneity in the lung was not different compared with short-duration exposure to microG. The results show that VC is essentially unchanged and respiratory muscle strength is maintained during extended exposure to microG, and metabolic rate is reduced. PMID:16601306

  4. Effects of sprint training combined with vegetarian or mixed diet on muscle carnosine content and buffering capacity.

    PubMed

    Baguet, Audrey; Everaert, Inge; De Naeyer, Hélène; Reyngoudt, Harmen; Stegen, Sanne; Beeckman, Sam; Achten, Eric; Vanhee, Lander; Volkaert, Anneke; Petrovic, Mirko; Taes, Youri; Derave, Wim

    2011-10-01

    Carnosine is an abundant dipeptide in human skeletal muscle with proton buffering capacity. There is controversy as to whether training can increase muscle carnosine and thereby provide a mechanism for increased buffering capacity. This study investigated the effects of 5 weeks sprint training combined with a vegetarian or mixed diet on muscle carnosine, carnosine synthase mRNA expression and muscle buffering capacity. Twenty omnivorous subjects participated in a 5 week sprint training intervention (2-3 times per week). They were randomized into a vegetarian and mixed diet group. Measurements (before and after the intervention period) included carnosine content in soleus, gastrocnemius lateralis and tibialis anterior by proton magnetic resonance spectroscopy ((1)H-MRS), true-cut biopsy of the gastrocnemius lateralis to determine in vitro non-bicarbonate muscle buffering capacity, carnosine content (HPLC method) and carnosine synthase (CARNS) mRNA expression and 6 × 6 s repeated sprint ability (RSA) test. There was a significant diet × training interaction in soleus carnosine content, which was non-significantly increased (+11%) with mixed diet and non-significantly decreased (-9%) with vegetarian diet. Carnosine content in other muscles and gastrocnemius buffer capacity were not influenced by training. CARNS mRNA expression was independent of training, but decreased significantly in the vegetarian group. The performance during the RSA test improved by training, without difference between groups. We found a positive correlation (r = 0.517; p = 0.002) between an invasive and non-invasive method for muscle carnosine quantification. In conclusion, this study shows that 5 weeks sprint training has no effect on the muscle carnosine content and carnosine synthase mRNA. PMID:21373871

  5. Forward Dynamics Simulations Provide insight into Muscle Mechanical Work during Human Locomotion

    PubMed Central

    Neptune, Richard R.; McGowan, Craig P.; Kautz, Steven A.

    2009-01-01

    Complex musculoskeletal models and computer simulations can provide critical insight into muscle mechanical work output during locomotion. Simulations provide both a consistent mechanical solution that can be interrogated at multiple levels (muscle fiber, musculotendon, net joint moment and whole body work) and an ideal framework to identify limitations with different estimates of muscle work and the resulting implications for metabolic cost and efficiency. PMID:19955870

  6. Upregulation of MHC class I in transgenic mice results in reduced force-generating capacity in slow-twitch muscle.

    PubMed

    Salomonsson, Stina; Grundtman, Cecilia; Zhang, Shi-Jin; Lanner, Johanna T; Li, Charles; Katz, Abram; Wedderburn, Lucy R; Nagaraju, Kanneboyina; Lundberg, Ingrid E; Westerblad, Håkan

    2009-05-01

    Expression of major histocompatibility complex (MHC) class I in skeletal muscle fibers is an early and consistent finding in inflammatory myopathies. To test if MHC class I has a primary role in muscle impairment, we used transgenic mice with inducible overexpression of MHC class I in their skeletal muscle cells. Contractile function was studied in isolated extensor digitorum longus (EDL, fast-twitch) and soleus (slow-twitch) muscles. We found that EDL was smaller, whereas soleus muscle was slightly larger. Both muscles generated less absolute force in myopathic compared with control mice; however, when force was expressed per cross-sectional area, only soleus muscle generated less force. Inflammation was markedly increased, but no changes were found in the activities of key mitochondrial and glycogenolytic enzymes in myopathic mice. The induction of MHC class I results in muscle atrophy and an intrinsic decrease in force-generation capacity. These observations may have important implications for our understanding of the pathophysiological processes of muscle weakness seen in inflammatory myopathies. Muscle Nerve, 2008. PMID:19229963

  7. Effect of reproduction on escape responses and muscle metabolic capacities in the scallop Chlamys islandica Müller 1776.

    PubMed

    Brokordt; Himmelman; Guderley

    2000-08-30

    In scallops, gametogenesis leads to mobilization of glycogen and proteins from the adductor muscle towards the gonad. This mobilization is likely to diminish the metabolic capacities of the adductor muscle and thereby the scallops' escape response. We examined the escape response in terms of number of valve claps until exhaustion, rate of clapping and the recovery during and after valve closure in adult scallops, Chlamys islandica, sampled at different stages in the reproductive cycle (immature, mature, before and after spawning). In parallel, we measured muscle glycogen, protein and phosphoarginine contents, the oxidative capacity of mitochondria isolated from the adductor muscle and levels of muscle enzymes which are active during exercise and recovery. The number of claps (24-26), rate of clapping ( approximately 13 clapsmin(-1)) and phosphoarginine and arginine kinase levels were similar during the different reproductive stages. All immature scallops responded to restimulation immediately after opening their valves, while only 62% of mature, 82% of prespawned and 38% of spawned scallops responded. Immature animals completely recovered their initial swimming capacity within 4 h of opening their valves, but mature, prespawned and spawned scallops needed 18, 12 and 18 h, respectively. Overall phasic adductor muscle from mature, prespawned and spawned animals showed decreased glycogen phosphorylase, phosphofructokinase, pyruvate kinase (except for prespawned), octopine dehydrogenase and citrate synthase levels, a deterioration of the oxidative capacity of mitochondria and a marked decrease in glycogen content compared to immature scallops. Therefore, during gonadal maturation and spawning, C. islandica did not change its clapping capacity, but slowed its recuperation from exhausting burst exercise, both during and after valve closure, likely due to the decreased metabolic capacity of the adductor muscle. PMID:10960615

  8. Differences in the Aerobic Capacity of Flight Muscles between Butterfly Populations and Species with Dissimilar Flight Abilities

    PubMed Central

    Rauhamäki, Virve; Wolfram, Joy; Jokitalo, Eija; Hanski, Ilkka; Dahlhoff, Elizabeth P.

    2014-01-01

    Habitat loss and climate change are rapidly converting natural habitats and thereby increasing the significance of dispersal capacity for vulnerable species. Flight is necessary for dispersal in many insects, and differences in dispersal capacity may reflect dissimilarities in flight muscle aerobic capacity. In a large metapopulation of the Glanville fritillary butterfly in the Åland Islands in Finland, adults disperse frequently between small local populations. Individuals found in newly established populations have higher flight metabolic rates and field-measured dispersal distances than butterflies in old populations. To assess possible differences in flight muscle aerobic capacity among Glanville fritillary populations, enzyme activities and tissue concentrations of the mitochondrial protein Cytochrome-c Oxidase (CytOx) were measured and compared with four other species of Nymphalid butterflies. Flight muscle structure and mitochondrial density were also examined in the Glanville fritillary and a long-distance migrant, the red admiral. Glanville fritillaries from new populations had significantly higher aerobic capacities than individuals from old populations. Comparing the different species, strong-flying butterfly species had higher flight muscle CytOx content and enzymatic activity than short-distance fliers, and mitochondria were larger and more numerous in the flight muscle of the red admiral than the Glanville fritillary. These results suggest that superior dispersal capacity of butterflies in new populations of the Glanville fritillary is due in part to greater aerobic capacity, though this species has a low aerobic capacity in general when compared with known strong fliers. Low aerobic capacity may limit dispersal ability of the Glanville fritillary. PMID:24416122

  9. A probabilistic model of visual working memory: Incorporating higher order regularities into working memory capacity estimates.

    PubMed

    Brady, Timothy F; Tenenbaum, Joshua B

    2013-01-01

    When remembering a real-world scene, people encode both detailed information about specific objects and higher order information like the overall gist of the scene. However, formal models of change detection, like those used to estimate visual working memory capacity, assume observers encode only a simple memory representation that includes no higher order structure and treats items independently from one another. We present a probabilistic model of change detection that attempts to bridge this gap by formalizing the role of perceptual organization and allowing for richer, more structured memory representations. Using either standard visual working memory displays or displays in which the items are purposefully arranged in patterns, we find that models that take into account perceptual grouping between items and the encoding of higher order summary information are necessary to account for human change detection performance. Considering the higher order structure of items in visual working memory will be critical for models to make useful predictions about observers' memory capacity and change detection abilities in simple displays as well as in more natural scenes. PMID:23230888

  10. The Total Work Measured During a High Intensity Isokinetic Fatigue Test Is Associated With Anaerobic Work Capacity

    PubMed Central

    Bosquet, Laurent; Gouadec, Kenan; Berryman, Nicolas; Duclos, Cyril; Gremeaux, Vincent; Croisier, Jean Louis

    2016-01-01

    The purpose of the study was to determine whether total work measured during a high intensity isokinetic fatigue test (TWFAT) could be considered as a valid measure of anaerobic work capacity (AWC), such as determined by total work measured during a Wingate Anaerobic Test (TWWAnT). Twenty well-trained cyclists performed 2 randomly ordered sessions involving a high intensity isokinetic fatigue test consisting in 30 reciprocal maximal concentric contractions of knee flexors and extensors at 180°·s-1, and a Wingate Anaerobic Test. We found that TWFAT of knee extensors was largely lower than TWWAnT (4151 ± 691 vs 22313 ± 2901 J, respectively, p < 0.05, Hedge’s g = 4.27). Both measures were highly associated (r = 0.83), and the 95% limits of agreement (LoA) represented 24.5% of TWWAnT. TWFAT of knee flexors (2151 ± 540 J) was largely lower than TWWAnT (p < 0.05, g = 9.52). By contrast, both measures were not associated (r = 0.09), and the 95% LoA represented 31.1% of TWWAnT. Combining TWFAT of knee flexors and knee extensors into a single measure (6302 ± 818 J) did not changed neither improved these observations. We still found a large difference with TWWAnT (p < 0.05, g = 5.26), a moderate association (r = 0.65) and 95% LoA representing 25.5% of TWWAnT. We concluded that TWFAT of knee extensors could be considered as a valid measure of AWC, since both measure were highly associated. However, the mean difference between both measures and their 95% LoA were too large to warrant interchangeability. Key points Total work performed during a high intensity isokinetic fatigue test can be considered as a valid measure of anaerobic work capacity (as determined by total work performance during a 30-s Wingate anaerobic test). The 95% limits of agreement are two large to allow a direct comparison between both measures. In other words, it is not possible to estimate the magnitude of performance improvement during a 30-s Wingate anaerobic test from that observed during a

  11. The Total Work Measured During a High Intensity Isokinetic Fatigue Test Is Associated With Anaerobic Work Capacity.

    PubMed

    Bosquet, Laurent; Gouadec, Kenan; Berryman, Nicolas; Duclos, Cyril; Gremeaux, Vincent; Croisier, Jean Louis

    2016-03-01

    The purpose of the study was to determine whether total work measured during a high intensity isokinetic fatigue test (TWFAT) could be considered as a valid measure of anaerobic work capacity (AWC), such as determined by total work measured during a Wingate Anaerobic Test (TWWAnT). Twenty well-trained cyclists performed 2 randomly ordered sessions involving a high intensity isokinetic fatigue test consisting in 30 reciprocal maximal concentric contractions of knee flexors and extensors at 180°·s(-1), and a Wingate Anaerobic Test. We found that TWFAT of knee extensors was largely lower than TWWAnT (4151 ± 691 vs 22313 ± 2901 J, respectively, p < 0.05, Hedge's g = 4.27). Both measures were highly associated (r = 0.83), and the 95% limits of agreement (LoA) represented 24.5% of TWWAnT. TWFAT of knee flexors (2151 ± 540 J) was largely lower than TWWAnT (p < 0.05, g = 9.52). By contrast, both measures were not associated (r = 0.09), and the 95% LoA represented 31.1% of TWWAnT. Combining TWFAT of knee flexors and knee extensors into a single measure (6302 ± 818 J) did not changed neither improved these observations. We still found a large difference with TWWAnT (p < 0.05, g = 5.26), a moderate association (r = 0.65) and 95% LoA representing 25.5% of TWWAnT. We concluded that TWFAT of knee extensors could be considered as a valid measure of AWC, since both measure were highly associated. However, the mean difference between both measures and their 95% LoA were too large to warrant interchangeability. Key pointsTotal work performed during a high intensity isokinetic fatigue test can be considered as a valid measure of anaerobic work capacity (as determined by total work performance during a 30-s Wingate anaerobic test).The 95% limits of agreement are two large to allow a direct comparison between both measures. In other words, it is not possible to estimate the magnitude of performance improvement during a 30-s Wingate anaerobic test from that observed during a high

  12. Reduced Skeletal Muscle Oxidative Capacity and Elevated Ceramide but not Diacylglycerol Content in Severe Obesity

    PubMed Central

    Coen, P.M.; Hames, K.C.; Leachman, E.M.; DeLany, J.P.; Ritov, V.B.; Menshikova, E.V.; Dubé, J.J.; Stefanovic-Racic, M.; Toledo, F.G.S.; Goodpaster, B.H.

    2014-01-01

    Objective The link between a reduced capacity for skeletal muscle mitochondrial fatty acid oxidation (FAO) and lipotoxicity in human insulin resistance has been the subject of intense debate. The objective of this study was to investigate whether reduced FAO is associated with elevated acyl CoA, ceramide, and diacylglycerol (DAG) in severely obese insulin resistant subjects. Design and Methods Muscle biopsies were conducted in lean (L, 22.6 ± 0.5 kg/m2, n = 8), Class I (CI, 32.1 ± 0.4 kg/m2, n = 7) and Class II&III obese (CII&III, 45.6 ± 1.1 kg/m2, n = 15) women for acyl CoA, sphingolipid and DAG profiling. Intramyocellular triglyceride (IMTG) content was determined by histology. FAO was assessed by incubating muscle homogenates with [1–14C]palmitate and measuring 14CO2 production. Cardiolipin content was quantified as an index of mitochondrial content. Lipid metabolism proteins, DGAT1, PLIN5, and PNPLA2 were quantified in biopsy samples by western blot. Results CII&III were more insulin resistant (HOMA-IR: 4.5 ± 0.5 vs. 1.1 ± 0.1, P < 0.001), and had lower FAO (~58%, P = 0.007) and cardiolipin content (~31%, P = 0.013) compared to L. IMTG was elevated in CI (P = 0.04) and CII&III (P = 0.04) compared to L. Sphingolipid content was higher in CII&III compared to L (13.6 ± 1.1 vs. 10.3 ± 0.5 pmol/mg, P = 0.031) whereas DAG content was not different among groups. DGAT1 was elevated in CII&III, and PLIN5 was elevated in CI compared to L. Conclusions Severe obesity is associated with reduced muscle oxidative capacity and occurs concomitantly with elevated IMTG, ceramide and insulin resistance. PMID:23512750

  13. Longitudinal and allometric variation in indicators of muscle metabolic capacities in atlantic cod (Gadus morrhua).

    PubMed

    Martínez, M; Dutil, J D; Guderley, H

    2000-06-15

    This study evaluated whether indicators of metabolic capacity of cod white muscle differ along the length of the body, whether this variation persists over a large range of body sizes, and whether the allometry of metabolic capacities is similar along the length of the body. We examined the maximal activities of two glycolytic enzymes, phosphofructokinase (PFK) and lactate dehydrogenase (LDH), a mitochondrial enzyme, cytochrome C oxidase (CCO), and the biosynthetic enzyme nucleotide diphosphate kinase (NDPK). All enzymes examined showed significant size dependence, which was generally apparent in all regions. The activity of glycolytic enzymes increased with size, whereas that of CCO and NDPK decreased with size. For PFK and LDH, the size dependence decreased caudally, whereas for CCO and NDPK it was strongest in the caudal sample. For each size range, the activities of PFK, LDH, and CCO were higher in the last third of the body than in the middle or just behind the head. In contrast, NDPK activity was higher just behind the head than at the middle or in the last third of the body, suggesting that nuclear proliferation is more rapid in this zone. The high capacity for adenosine triphosphate (ATP) generation in the caudal region suggests that increases in mass-specific ATP output are advantageous in this relatively thin section of the body. PMID:10861548

  14. Shoulder muscle loading and task performance for overhead work on ladders versus Mobile Elevated Work Platforms.

    PubMed

    Phelan, Denis; O'Sullivan, Leonard

    2014-11-01

    A high incidence of Musculoskeletal Disorders (MSDs) has been reported in the construction sector. The use of ladders in the workplace has long been identified as a significant risk that can lead to workplace accidents. However, it is unclear if platform types have an effect on the physical risk factors for MSDs in overhead work. The aim of this study is to perform a pilot study on the effects of hand activity on both shoulder muscle loading and task performance while working on ladders versus Mobile Elevated Working Platforms (MEWPs). It is hypothesised that work on ladders would result in greater muscle loading demands, increased levels of discomfort, and reduced performance due to the restrictions on postures that could be adopted. A field study (n = 19) of experienced electricians on a construction site found that workers spent approximately 28% of their working time on ladders versus 6% on MEWPs. However, the durations of individual tasks were higher on MEWPs (153 s) than on ladders (73 s). Additionally, maximum levels of perceived discomfort (on a VAS 0-100) were reported for the shoulders (27), neck (23), and lower regions of the body (22). A simulated study (n = 12) found that task performance and discomfort were not significantly different between platform types (ladder vs. MEWP) when completing either of three tasks: cabling, assembly and drilling. However, platform and task had significant effects (p < 0.05) on median electromyographic (EMG) activity of the anterior deltoid and upper trapezius. EMG amplitudes were higher for the deltoid than the upper trapezius. For the deltoid, the peak amplitudes were, on average, higher for ladder work over MEWP work for the hand intensive cabling (32 vs. 27% Maximal Voluntary Exertion (MVE)) and the assembly task (19 vs. 6% MVE). Conversely, for drilling, the peak EMG amplitudes were marginally lower for ladder compared to the MEWP (3.9 vs. 5.1% MVE). The general implication was that working on the MEWP

  15. Heat work and phosphorylcreatine break-down in muscle

    PubMed Central

    Wilkie, D. R.

    1968-01-01

    1. A new instrument, the integrating thermopile, is described for measuring the total quantity of heat produced during muscular contraction. 2. This instrument has been used to investigate the relation between change of enthalpy (- (heat produced + work produced)) and break-down of phosphorylcreatine (ΔPC) in iodoacetate-poisoned frog sartorii at 0° C. In a variety of different types of contraction—series of isometric twitches, isometric tetani, contractions with positive and with negative work—the relation between enthalpy change and ΔPC was always the same, and corresponded to an in vivo molar enthalpy change (ΔH) of -11·0 ± 0·23 (S.E.; n = 52) kcal/mole. 3. This value of ΔH is used to estimate the in vivo ΔH for ATP splitting and also the number of rephosphorylations to be expected per hexose unit oxidized by normal unpoisoned muscle. ImagesFig. 2 PMID:5639798

  16. [Skin temperature and lactate threshold during muscle work in sportsmen].

    PubMed

    Akimov, E B; Son'kin, V D

    2011-01-01

    The purpose of the investigation was to estimate change of a thermal condition of an organism during exhausting work (maximal aerobic test) on cycle ergometer on the basis of studying of dynamics of temperature of a forehead skin. Regularly training 20 men have taken part in the research--sportsmen of various specializations (skiers, rock-climbers, boxers, etc.). Temperature of forehead skin was registered by infrared thermovision chamber Nec TH 9100SL. These results compared with the data of measurements of heart rate, gas exchange, the lactate concentration in peripheral blood, and also with anthropometrical characteristics. It was shown that on dynamics of skin temperature at maximal work load it was possible to divide all subjects into 2 unequal groups: 1 (2/3 subjects, the majority of which trains endurance) - after temperature decrease take place its smooth increase up to refusal ofwork; 2 (1/3 subjects, concerning various sports specializations)--from the moment of the beginning of active evaporation of sweat the temperature decreases to the work termination. In group 1 lactate threshold (lactate concentration in blood--4 mm/l) corresponds to the beginning of rise in temperature after its decrease as a result of sweat evaporation. In group 2 lactate threshold was necessary on a phase of decrease in temperature at the moment of active evaporation of sweat. Distinctions between groups in structure of correlation relationship between the measured indicators are revealed, inversion of a sign ofcorrelation quotient in some cases were shown. Thus significant distinctions between groups in the level of the working capacity indicators were not revealed. All it testifies to existence possibility at least two various successful strategy of urgent adaptation of system of thermoregulation to intense muscular work. PMID:22117467

  17. When High-Capacity Readers Slow Down and Low-Capacity Readers Speed Up: Working Memory and Locality Effects.

    PubMed

    Nicenboim, Bruno; Logačev, Pavel; Gattei, Carolina; Vasishth, Shravan

    2016-01-01

    We examined the effects of argument-head distance in SVO and SOV languages (Spanish and German), while taking into account readers' working memory capacity and controlling for expectation (Levy, 2008) and other factors. We predicted only locality effects, that is, a slowdown produced by increased dependency distance (Gibson, 2000; Lewis and Vasishth, 2005). Furthermore, we expected stronger locality effects for readers with low working memory capacity. Contrary to our predictions, low-capacity readers showed faster reading with increased distance, while high-capacity readers showed locality effects. We suggest that while the locality effects are compatible with memory-based explanations, the speedup of low-capacity readers can be explained by an increased probability of retrieval failure. We present a computational model based on ACT-R built under the previous assumptions, which is able to give a qualitative account for the present data and can be tested in future research. Our results suggest that in some cases, interpreting longer RTs as indexing increased processing difficulty and shorter RTs as facilitation may be too simplistic: The same increase in processing difficulty may lead to slowdowns in high-capacity readers and speedups in low-capacity ones. Ignoring individual level capacity differences when investigating locality effects may lead to misleading conclusions. PMID:27014113

  18. When High-Capacity Readers Slow Down and Low-Capacity Readers Speed Up: Working Memory and Locality Effects

    PubMed Central

    Nicenboim, Bruno; Logačev, Pavel; Gattei, Carolina; Vasishth, Shravan

    2016-01-01

    We examined the effects of argument-head distance in SVO and SOV languages (Spanish and German), while taking into account readers' working memory capacity and controlling for expectation (Levy, 2008) and other factors. We predicted only locality effects, that is, a slowdown produced by increased dependency distance (Gibson, 2000; Lewis and Vasishth, 2005). Furthermore, we expected stronger locality effects for readers with low working memory capacity. Contrary to our predictions, low-capacity readers showed faster reading with increased distance, while high-capacity readers showed locality effects. We suggest that while the locality effects are compatible with memory-based explanations, the speedup of low-capacity readers can be explained by an increased probability of retrieval failure. We present a computational model based on ACT-R built under the previous assumptions, which is able to give a qualitative account for the present data and can be tested in future research. Our results suggest that in some cases, interpreting longer RTs as indexing increased processing difficulty and shorter RTs as facilitation may be too simplistic: The same increase in processing difficulty may lead to slowdowns in high-capacity readers and speedups in low-capacity ones. Ignoring individual level capacity differences when investigating locality effects may lead to misleading conclusions. PMID:27014113

  19. Decreased functional capacity and muscle strength in elderly women with metabolic syndrome

    PubMed Central

    Vieira, Denis Cesar Leite; Tibana, Ramires Alsamir; Tajra, Vitor; Nascimento, Dahan da Cunha; de Farias, Darlan Lopes; de Oliveira Silva, Alessandro; Teixeira, Tatiane Gomes; Fonseca, Romulo Maia Carlos; de Oliveira, Ricardo Jacó; Mendes, Felipe Augusto dos Santos; Martins, Wagner Rodrigues; Funghetto, Silvana Schwerz; de Oliveira Karnikowski, Margo Gomes; Navalta, James Wilfred; Prestes, Jonato

    2013-01-01

    Purpose To compare the metabolic parameters, flexibility, muscle strength, functional capacity, and lower limb muscle power of elderly women with and without the metabolic syndrome (MetS). Methods This cross-sectional study included 28 older women divided into two groups: with the MetS (n = 14; 67.3 ± 5.5 years; 67.5 ± 16.7 kg; 1.45 ± 0.35 m; 28.0 ± 7.6 kg/m2), and without the MetS (n = 14; 68.7 ± 5.3 years; 58.2 ± 9.9 kg; 1.55 ± 0.10 m; 24.3 ± 3.8 kg/m2). Body composition was evaluated by dual-energy X-ray absorptiometry and dynamic muscle strength was assessed by one-maximum repetition (1RM) tests in leg press, bench press and biceps curl exercises. Six-minute walk test, Timed Up and Go (TUG); 30-second sitting-rising; arm curl using a 2-kg dumbbell, sit-and-reach (flexibility), and vertical jump tests were performed. Results There was no difference between groups regarding age (P = 0.49), height (P = 0.46), body fat (%) (P = 0.19), systolic (P = 0.64), diastolic (P = 0.41) and mean blood pressure (P = 0.86), 30-second sitting-rising (P = 0.57), 30-s arm curl (P = 0.73), leg press 1RM (P = 0.51), bench press 1RM (P = 0.77), and biceps curl 1RM (P = 0.85). However, women without the MetS presented lower body mass (P = 0.001), body mass index (BMI) (P = 0.0001), waist circumference (P = 0.02), waist-to-height ratio (P = 0.02), fat body mass (kg) (P = 0.05), lean body mass (kg) (P = 0.02), blood glucose (P = 0.05), triglycerides (P = 0.03), Z-score for the MetS (P = 0.05), higher high-density lipoprotein-cholesterol (HDL-C) (P = 0.002), better performance on TUG (P = 0.01), flexibility (P = 0.03), six-minute walk test (P = 0.04), vertical jump (P = 0.05) and relative muscle strength for leg press (P = 0.03), bench press (P = 0.04) and biceps curl (P = 0.002) exercises as compared to women with the MetS. Conclusion Elderly women with the MetS have higher metabolic risk profile and lower functional capacity, muscle strength, lower limb power and flexibility as

  20. The effect of training during treatment with chemotherapy on muscle strength and endurance capacity: A systematic review.

    PubMed

    Van Moll, Christel C A; Schep, Goof; Vreugdenhil, Art; Savelberg, Hans H C M; Husson, Olga

    2016-05-01

    Background Treatment of cancer with chemotherapy decreases endurance capacity and muscle strength. Training during chemotherapy might prevent this. There are no clear guidelines concerning which type of training and which training dose are effective. This review aims to gain insight into the different training modalities during chemotherapy and the effects of such training to improve endurance capacity and muscle strength in order to obtain the knowledge to compose a future training program which trains cancer patients in the most effective way. Material and methods A systematic search of PubMed was carried out. In total, 809 studies of randomized controlled trials studying the effects of training during chemotherapy on endurance capacity and muscle strength were considered. Only 14 studies met all the inclusion criteria. The studies were assessed on methodological quality by using Cochrane criteria for randomized controlled trials. Results The quality of the studies was generally poor and the study populations varied considerably as the training programs were very heterogeneous. Variables of endurance capacity reported beneficial effects in 10 groups (59%). Increases due to training ranged from 8% to 31%. Endurance capacity decreased in nine of 13 control groups (69%), which ranged from 1% to 32%. Muscle strength improved significantly in 17 of 18 intervention groups (94%), ranging from 2% to 38%. Muscle strength also improved in 11 of 14 control groups (79%), but this increase was only minimal, ranging from 1.3% to 6.5%. Conclusions This review indicates that training during chemotherapy may help in preventing the decrease in muscle strength and endurance capacity. It is important to know which training intensity and duration is the most effective in training cancer patients, to provide a training program suitable for every cancer patient. Training should be based on good research and should be implemented into international guidelines and daily practice. More

  1. Strength training improves muscle aerobic capacity and glucose tolerance in elderly.

    PubMed

    Frank, P; Andersson, E; Pontén, M; Ekblom, B; Ekblom, M; Sahlin, K

    2016-07-01

    The primary aim of this study was to investigate the effect of short-term resistance training (RET) on mitochondrial protein content and glucose tolerance in elderly. Elderly women and men (age 71 ± 1, mean ± SEM) were assigned to a group performing 8 weeks of resistance training (RET, n = 12) or no training (CON, n = 9). The RET group increased in (i) knee extensor strength (concentric +11 ± 3%, eccentric +8 ± 3% and static +12 ± 3%), (ii) initial (0-30 ms) rate of force development (+52 ± 26%) and (iii) contents of proteins related to signaling of muscle protein synthesis (Akt +69 ± 20 and mammalian target of rapamycin +69 ± 32%). Muscle fiber type composition changed to a more oxidative profile in RET with increased amount of type IIa fibers (+26.9 ± 6.8%) and a trend for decreased amount of type IIx fibers (-16.4 ± 18.2%, P = 0.068). Mitochondrial proteins (OXPHOS complex II, IV, and citrate synthase) increased in RET by +30 ± 11%, +99 ± 31% and +29 ± 8%, respectively. RET resulted in improved oral glucose tolerance measured as reduced area under curve for glucose (-21 ± 26%) and reduced plasma glucose 2 h post-glucose intake (-14 ± 5%). In CON parameters were unchanged or impaired. In conclusion, short-term resistance training in elderly not only improves muscular strength, but results in robust increases in several parameters related to muscle aerobic capacity. PMID:26271931

  2. Does the aerobic capacity of fish muscle change with growth rates?

    PubMed

    Pelletier, D; Guderley, H; Dutil, J D

    1993-08-01

    To ascertain whether growth rate modifies the oxidative capacity of fish white muscle, we examined the effects of individual growth rate on the activities of four mitochondrial enzymes in white muscle of the fast growing Atlantic cod,Gadus morhua. Growth rates were individually monitored in cod held at three acclimation temperatures during experiments repeated in four seasons. The size dependence of citrate synthase (CS), cytochrome C oxidase (CCO) and β-hydroxyacyl CoA dehydrogenase (HOAD) activities was established using wild cod ranging from 115 to 17,350 g. Given their negative allometry, CS and CCO activities in the experimental cod were corrected to those expected for a 1.2 kg animal. HOAD activities did not change with size. The specific activities of CCO and CS were positively correlated with growth rate. However, for both enzymes, season explained more of the variability than growth rate or temperature. Season was the only factor to significantly affect the activity of HOAD, while temperature and season interacted to determine glutamate dehydrogenase activity. CS activity was positively correlated with the initial condition of the cod, which differed among the seasons. The other enzymes did not show this relationship. The independent changes of these enzymes suggest that mitochondria undergo qualitative modifications with changes in growth rate, season and size. Although growth rate and the activities of CCO and CS are positively correlated, the activity of the mitochondrial enzymes is more affected by size, physical condition and season. PMID:24202687

  3. Short-duration intermittent hypoxia enhances endurance capacity by improving muscle fatty acid metabolism in mice.

    PubMed

    Suzuki, Junichi

    2016-04-01

    This study was designed to (1) investigate the effects of acute short-duration intermittent hypoxia on musclemRNAand microRNAexpression levels; and (2) clarify the mechanisms by which short-duration intermittent hypoxia improves endurance capacity. Experiment-1: Male mice were subjected to either acute 1-h hypoxia (12% O2), acute short-duration intermittent hypoxia (12% O2for 15 min, room air for 10 min, 4 times, Int-Hypo), or acute endurance exercise (Ex). The expression of vascular endothelial growth factor-AmRNAwas significantly greater than the control at 0 h post Ex and 6 h post Int-Hypo in the deep red region of the gastrocnemius muscle. miR-16 expression levels were significantly lower at 6 and 10 h post Int-Hypo. Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α)mRNAlevels were significantly greater than the control at 3 h post Ex and 6 h post Int-Hypo. miR-23a expression levels were lower than the control at 6-24 h post Int-Hypo. Experiment-2: Mice were subjected to normoxic exercise training with or without intermittent hypoxia for 3 weeks. Increases in maximal exercise capacity were significantly greater by training with short-duration intermittent hypoxia (IntTr) than without hypoxia. Both 3-Hydroxyacyl-CoA-dehydrogenase and total carnitine palmitoyl transferase activities were significantly enhanced in IntTr. Peroxisome proliferator-activated receptor delta andPGC-1α mRNAlevels were both significantly greater in IntTr than in the sedentary controls. These results suggest that exercise training under normoxic conditions with exposure to short-duration intermittent hypoxia represents a beneficial strategy for increasing endurance performance by enhancing fatty acid metabolism in skeletal muscle. PMID:27044851

  4. Work done by titin protein folding assists muscle contraction

    PubMed Central

    Popa, Ionel; Kosuri, Pallav; Linke, Wolfgang A.; Fernández, Julio M.

    2016-01-01

    Current theories of muscle contraction propose that the power stroke of a myosin motor is the sole source of mechanical energy driving the sliding filaments of a contracting muscle. These models exclude titin, the largest protein in the human body, which determines the passive elasticity of muscles. Here, we show that stepwise unfolding/folding of titin Ig domains occurs in the elastic I band region of intact myofibrils at physiological sarcomere lengths and forces of 6-8 pN. We use single molecule techniques to demonstrate that unfolded titin Ig domains undergo a spontaneous stepwise folding contraction at forces below 10 pN, delivering up to 105 zJ of additional contractile energy, which is larger than the mechanical energy delivered by the power stroke of a myosin motor. Thus, it appears inescapable that folding of titin Ig domains is an important, but so far unrecognized contributor to the force generated by a contracting muscle. PMID:26854230

  5. Effect of diet and temperature upon muscle metabolic capacities and biochemical composition of gonad and muscle in Argopecten purpuratus Lamarck 1819.

    PubMed

    Martínez; Brokordt; Aguilera; Soto; Guderley

    2000-04-26

    Recently spawned Argopecten purpuratus broodstock were conditioned at two temperatures and fed three different diets (microalgae, microalgae mixed with lipids and microalgae mixed with carbohydrates) to examine changes in the biochemical composition of gonad and muscle as well as muscle metabolic capacities. During one experiment, scallops were fed at 3% of their dry mass per day whereas during a second experiment, they were fed at 6% of their dry mass per day. During both experiments, total gonadal levels of lipids and protein increased markedly during conditioning with the two mixed diets at 16 degrees C. These increases were less pronounced at 20 degrees C. Carbohydrate gonadal levels only increased during the second experiment at both temperatures and with the three diets. Of the major biochemical components of the adductor muscle, carbohydrate levels changed most during conditioning. Whereas muscle protein levels increased slightly with gonadal maturation, carbohydrate levels dropped considerably. Despite the marked drop in the levels of glycolytic substrates, only the activities of octopine dehydrogenase in the adductor muscle of the scallops conditioned at 16 degrees C consistently decreased. Muscle levels of glycogen phosphorylase were higher in mature than in recently spawned (control) scallops, suggesting a role in the transfer of glucose equivalents from the adductor muscle to other tissues. PMID:10727686

  6. Working memory is not fixed-capacity: More active storage capacity for real-world objects than for simple stimuli.

    PubMed

    Brady, Timothy F; Störmer, Viola S; Alvarez, George A

    2016-07-01

    Visual working memory is the cognitive system that holds visual information active to make it resistant to interference from new perceptual input. Information about simple stimuli-colors and orientations-is encoded into working memory rapidly: In under 100 ms, working memory ‟fills up," revealing a stark capacity limit. However, for real-world objects, the same behavioral limits do not hold: With increasing encoding time, people store more real-world objects and do so with more detail. This boost in performance for real-world objects is generally assumed to reflect the use of a separate episodic long-term memory system, rather than working memory. Here we show that this behavioral increase in capacity with real-world objects is not solely due to the use of separate episodic long-term memory systems. In particular, we show that this increase is a result of active storage in working memory, as shown by directly measuring neural activity during the delay period of a working memory task using EEG. These data challenge fixed-capacity working memory models and demonstrate that working memory and its capacity limitations are dependent upon our existing knowledge. PMID:27325767

  7. Two weeks of one-leg immobilization decreases skeletal muscle respiratory capacity equally in young and elderly men.

    PubMed

    Gram, Martin; Vigelsø, Andreas; Yokota, Takashi; Hansen, Christina Neigaard; Helge, Jørn Wulff; Hey-Mogensen, Martin; Dela, Flemming

    2014-10-01

    Physical inactivity affects human skeletal muscle mitochondrial oxidative capacity but the influence of aging combined with physical inactivity is not known. This study investigates the effect of two weeks of immobilization followed by six weeks of supervised cycle training on muscle oxidative capacity in 17 young (23±1years) and 15 elderly (68±1years) healthy men. We applied high-resolution respirometry in permeabilized fibers from muscle biopsies at inclusion after immobilization and training. Furthermore, protein content of mitochondrial complexes I-V, mitochondrial heat shock protein 70 (mtHSP70) and voltage dependent anion channel (VDAC) were measured in skeletal muscle by Western blotting. The elderly men had lower content of complexes I-V and mtHSP70 but similar respiratory capacity and content of VDAC compared to the young. In both groups the respiratory capacity and protein content of VDAC, mtHSP70 and complexes I, II, IV and V decreased with immobilization and increased with retraining. Moreover, there was no overall difference in the response between the groups. When the intrinsic mitochondrial capacity was evaluated by normalizing respiration to citrate synthase activity, the respiratory differences with immobilization and training disappeared. In conclusion, aging is not associated with a decrease in muscle respiratory capacity in spite of lower complexes I-V and mtHSP70 protein content. Furthermore, immobilization decreased and aerobic training increased the respiratory capacity and protein contents of complexes I-V, mtHSP70 and VDAC similarly in the two groups. This suggests that inactivity and training alter mitochondrial biogenesis equally in young and elderly men. PMID:25193555

  8. The energetic benefits of tendon springs in running: is the reduction of muscle work important?

    PubMed Central

    Holt, Natalie C.; Roberts, Thomas J.; Askew, Graham N.

    2014-01-01

    The distal muscle-tendon units of cursorial species are commonly composed of short muscle fibres and long, compliant tendons. It is assumed that the ability of these tendons to store and return mechanical energy over the course of a stride, thus avoiding the cyclic absorption and regeneration of mechanical energy by active muscle, offers some metabolic energy savings during running. However, this assumption has not been tested directly. We used muscle ergometry and myothermic measurements to determine the cost of force production in muscles acting isometrically, as they could if mechanical energy was stored and returned by tendon, and undergoing active stretch–shorten cycles, as they would if mechanical energy was absorbed and regenerated by muscle. We found no detectable difference in the cost of force production in isometric cycles compared with stretch–shorten cycles. This result suggests that replacing muscle stretch–shorten work with tendon elastic energy storage and recovery does not reduce the cost of force production. This calls into question the assumption that reduction of muscle work drove the evolution of long distal tendons. We propose that the energetic benefits of tendons are derived primarily from their effect on muscle and limb architecture rather than their ability to reduce the cyclic work of muscle. PMID:25394624

  9. The energetic benefits of tendon springs in running: is the reduction of muscle work important?

    PubMed

    Holt, Natalie C; Roberts, Thomas J; Askew, Graham N

    2014-12-15

    The distal muscle-tendon units of cursorial species are commonly composed of short muscle fibres and long, compliant tendons. It is assumed that the ability of these tendons to store and return mechanical energy over the course of a stride, thus avoiding the cyclic absorption and regeneration of mechanical energy by active muscle, offers some metabolic energy savings during running. However, this assumption has not been tested directly. We used muscle ergometry and myothermic measurements to determine the cost of force production in muscles acting isometrically, as they could if mechanical energy was stored and returned by tendon, and undergoing active stretch-shorten cycles, as they would if mechanical energy was absorbed and regenerated by muscle. We found no detectable difference in the cost of force production in isometric cycles compared with stretch-shorten cycles. This result suggests that replacing muscle stretch-shorten work with tendon elastic energy storage and recovery does not reduce the cost of force production. This calls into question the assumption that reduction of muscle work drove the evolution of long distal tendons. We propose that the energetic benefits of tendons are derived primarily from their effect on muscle and limb architecture rather than their ability to reduce the cyclic work of muscle. PMID:25394624

  10. Maximal oxygen uptake is proportional to muscle fiber oxidative capacity, from chronic heart failure patients to professional cyclists.

    PubMed

    van der Zwaard, Stephan; de Ruiter, Jo C; Noordhof, Dionne A; Sterrenburg, Renske; Bloemers, Frank W; de Koning, Jos J; Jaspers, Richard T; van der Laarse, Willem J

    2016-09-01

    V̇o2 max during whole body exercise is presumably constrained by oxygen delivery to mitochondria rather than by mitochondria's ability to consume oxygen. Humans and animals have been reported to exploit only 60-80% of their mitochondrial oxidative capacity at maximal oxygen uptake (V̇o2 max). However, ex vivo quantification of mitochondrial overcapacity is complicated by isolation or permeabilization procedures. An alternative method for estimating mitochondrial oxidative capacity is via enzyme histochemical quantification of succinate dehydrogenase (SDH) activity. We determined to what extent V̇o2 max attained during cycling exercise differs from mitochondrial oxidative capacity predicted from SDH activity of vastus lateralis muscle in chronic heart failure patients, healthy controls, and cyclists. V̇o2 max was assessed in 20 healthy subjects and 28 cyclists, and SDH activity was determined from biopsy cryosections of vastus lateralis using quantitative histochemistry. Similar data from our laboratory of 14 chronic heart failure patients and 6 controls were included. Mitochondrial oxidative capacity was predicted from SDH activity using estimated skeletal muscle mass and the relationship between ex vivo fiber V̇o2 max and SDH activity of isolated single muscle fibers and myocardial trabecula under hyperoxic conditions. Mitochondrial oxidative capacity predicted from SDH activity was related (r(2) = 0.89, P < 0.001) to V̇o2 max measured during cycling in subjects with V̇o2 max ranging from 9.8 to 79.0 ml·kg(-1)·min(-1) V̇o2 max measured during cycling was on average 90 ± 14% of mitochondrial oxidative capacity. We conclude that human V̇o2 max is related to mitochondrial oxidative capacity predicted from skeletal muscle SDH activity. Mitochondrial oxidative capacity is likely marginally limited by oxygen supply to mitochondria. PMID:27445298

  11. Working Memory Capacity and Categorization: Individual Differences and Modeling

    ERIC Educational Resources Information Center

    Lewandowsky, Stephan

    2011-01-01

    Working memory is crucial for many higher-level cognitive functions, ranging from mental arithmetic to reasoning and problem solving. Likewise, the ability to learn and categorize novel concepts forms an indispensable part of human cognition. However, very little is known about the relationship between working memory and categorization, and…

  12. Dietary fatty acid composition changes mitochondrial phospholipids and oxidative capacities in rainbow trout red muscle.

    PubMed

    Guderley, H; Kraffe, E; Bureau, W; Bureau, D P

    2008-03-01

    Dietary conditioning of juvenile trout changed the acyl chain composition of mitochondrial phospholipids and the oxidative capacities of muscle mitochondria. Trout were fed three diets differing only in fatty acid (FA) composition. The highly unsaturated 22:6 n-3 (DHA) accounted for 0.4, 14, and 30% of fatty acids in Diets 1, 2 and 3. After 10 weeks of growth, the dietary groups differed markedly in FA composition of mitochondrial phospholipids, with significant dietary effects for virtually all FA. Mean mitochondrial DHA levels were 19, 40 and 33% in trout fed Diets 1, 2 and 3. Mitochondrial oxidative capacities changed with diet, while mitochondrial concentrations of cytochromes and of the adenylate nucleotide translocase (nmol mg(1) protein) did not. Mitochondria from fish fed Diet 1 had higher non-phosphorylating (state 4) rates at 5 degrees C than those fed other diets. When phosphorylating (state 3) rates differed between dietary groups, rates at 5 and 15 degrees C were higher for fish fed the more unsaturated diets. Stepwise multiple regressions indicated that FA composition could explain much (42-70%) of the variability of state 4 rates, particularly at 5 degrees C. At 15 degrees C, FA composition explained 16-42% of the variability of states 3 and 4 rates. Similar conclusions were obtained for the complete data set (trout fed diets 1, 2 and 3) and for the data from trout achieving similar growth rates (e.g. those fed Diets 1 and 2). Neither general characteristics of membrane FA, such as % saturates, unsaturation index, n-3, n-6 or n-3/n-6 nor levels of abundant unsaturated FA such as DHA or 18:1(n-9 + n-7), were systematically correlated with mitochondrial capacities even though they differed considerably between trout fed the different diets. Relatively minor FA (20:5n-3, 20:0, 18:2n-6, 18:3n-3, 18:0 and 15:0) showed better correlations with mitochondrial oxidative capacities. This supports the concept that acyl chain composition modulates mitochondrial

  13. High fatty acid oxidation capacity and phosphorylation control despite elevated leak and reduced respiratory capacity in northern elephant seal muscle mitochondria.

    PubMed

    Chicco, Adam J; Le, Catherine H; Schlater, Amber; Nguyen, Alex; Kaye, Spencer; Beals, Joseph W; Scalzo, Rebecca L; Bell, Christopher; Gnaiger, Erich; Costa, Daniel P; Crocker, Daniel E; Kanatous, Shane B

    2014-08-15

    Northern elephant seals (Mirounga angustirostris) are extreme, hypoxia-adapted endotherms that rely largely on aerobic metabolism during extended breath-hold dives in near-freezing water temperatures. While many aspects of their physiology have been characterized to account for these remarkable feats, the contribution of adaptations in the aerobic powerhouses of muscle cells, the mitochondria, are unknown. In the present study, the ontogeny and comparative physiology of elephant seal muscle mitochondrial respiratory function was investigated under a variety of substrate conditions and respiratory states. Intact mitochondrial networks were studied by high-resolution respirometry in saponin-permeabilized fiber bundles obtained from primary swimming muscles of pup, juvenile and adult seals, and compared with fibers from adult human vastus lateralis. Results indicate that seal muscle maintains a high capacity for fatty acid oxidation despite a progressive decrease in total respiratory capacity as animals mature from pups to adults. This is explained by a progressive increase in phosphorylation control and fatty acid utilization over pyruvate in adult seals compared with humans and seal pups. Interestingly, despite higher indices of oxidative phosphorylation efficiency, juvenile and adult seals also exhibit a ~50% greater capacity for respiratory 'leak' compared with humans and seal pups. The ontogeny of this phenotype suggests it is an adaptation of muscle to the prolonged breath-hold exercise and highly variable ambient temperatures experienced by mature elephant seals. These studies highlight the remarkable plasticity of mammalian mitochondria to meet the demands for both efficient ATP production and endothermy in a cold, oxygen-limited environment. PMID:24902742

  14. Stronger Neural Dynamics Capture Changes in Infants' Visual Working Memory Capacity over Development

    ERIC Educational Resources Information Center

    Perone, Sammy; Simmering, Vanessa R.; Spencer, John P.

    2011-01-01

    Visual working memory (VWM) capacity has been studied extensively in adults, and methodological advances have enabled researchers to probe capacity limits in infancy using a preferential looking paradigm. Evidence suggests that capacity increases rapidly between 6 and 10 months of age. To understand how the VWM system develops, we must understand…

  15. Team work increases fractionation capacity cost-effectively

    SciTech Connect

    Talib, J.H.; Germinder, B.; Hitchcock, M.P.

    1997-10-01

    During the early stages of the Discovery project in 1996, Texaco-Bridgeline Gas Distribution LLC planned on refurbishing an existing mothballed four-column fractionation facility at Paradis, Louisiana. The goal was to process Y-grade feed from a new 600 MMscfd cryogenic gas processing plant at Larose, Louisiana, and from the existing cryogenic facilities at Paradis. The Paradis debottlenecking team (PDT) met its goals by identifying and removing obvious process bottlenecks, minimizing costs and eliminating schedule impact, while increasing the Paradis facility fractionation capacity from 34,000 bpd to 42,000 bpd. The changes were implemented in record time. Following is a fine example of true teamwork and superior achievement of results against all obstacles.

  16. Marination effects on water states and water-holding capacity of broiler pectoralis major muscle with different color lightness

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Experiments were carried out to investigate the effect of marination on water states and water-holding capacity (WHC) of broiler pectoralis (p.) major muscle. Boneless, skinless p. major were collected 6-8 h postmortem from deboning lines at a commercial processing plant, and separated into light, ...

  17. Effect of training on maximal oxygen uptake and aerobic capacity of locomotory muscles in tufted ducks, Aythya fuligula.

    PubMed

    Butler, P J; Turner, D L

    1988-07-01

    1. The effects of artificial swim training on maximal oxygen consumption and heart rate, as well as on the capillarity and oxidative capacity of locomotory muscles, have been studied in the tufted duck, Aythya fuligula. 2. The artificial training programme resulted in a 27% increase in maximal oxygen consumption, mainly as a result of an increase in muscle capillarity (20% increase in capillary/fibre ratio). In addition, activity of an oxidative enzyme, citrate synthase, increased (by 42%) and there was a significant transformation of fibre types in the lateral gastrocnemius muscle. 3. Altering the duration and nature of the training stimulus, for example flying and diving, can bring about different degrees of muscular adaptation, particularly in oxidative capacity. PMID:3171990

  18. Effect of training on maximal oxygen uptake and aerobic capacity of locomotory muscles in tufted ducks, Aythya fuligula.

    PubMed Central

    Butler, P J; Turner, D L

    1988-01-01

    1. The effects of artificial swim training on maximal oxygen consumption and heart rate, as well as on the capillarity and oxidative capacity of locomotory muscles, have been studied in the tufted duck, Aythya fuligula. 2. The artificial training programme resulted in a 27% increase in maximal oxygen consumption, mainly as a result of an increase in muscle capillarity (20% increase in capillary/fibre ratio). In addition, activity of an oxidative enzyme, citrate synthase, increased (by 42%) and there was a significant transformation of fibre types in the lateral gastrocnemius muscle. 3. Altering the duration and nature of the training stimulus, for example flying and diving, can bring about different degrees of muscular adaptation, particularly in oxidative capacity. PMID:3171990

  19. Morphometry, ultrastructure, myosin isoforms, and metabolic capacities of the "mini muscles" favoured by selection for high activity in house mice.

    PubMed

    Guderley, Helga; Houle-Leroy, Philippe; Diffee, Gary M; Camp, Dana M; Garland, Theodore

    2006-07-01

    Prolonged selective breeding of mice (Mus musculus) for high levels of voluntary wheel running has favoured an unusual phenotype ("mini muscles"), apparently caused by a single Mendelian recessive allele, in which most hind-limb muscles are markedly reduced in mass, but have increased mass-specific activities of mitochondrial enzymes. We examined whether these changes reflect changes in fibre size, number or ultrastructure in normal and "mini-muscle" mice within the two (of four) selectively bred lines (lab designations L3 and L6) that exhibit the phenotype at generations 26 and 27. In both lines, the gastrocnemius and plantaris muscles are smaller in mass (by >50% and 20%, respectively) in affected individuals. The mass-specific activities of mitochondrial enzymes in the gastrocnemius and plantaris muscles were increased in the mini phenotype in both lines, with stronger effects in the gastrocnemius muscle. In the gastrocnemius, the % myosin heavy chain (MHC) IIb was reduced by 50% in L3 and by 30% in L6, whereas the % MHC IIa and I were higher, particularly in L3. Fibre number in the plantaris muscle did not significantly differ between mini and normal muscles, although muscle mass was a significant positive correlate of fibre number. Small fibres were more abundant in mini than normal muscles in L3. Mitochondrial volume density was significantly higher in mini than normal muscle fibres in L3, but not in L6. Microscopy revealed a surprising attribute of the mini muscles: an abundance of small, minimally differentiated, myofibril-containing cells positioned in a disorderly fashion, particularly in the surface layer. We hypothesise that these unusual cells may be satellite cells or type IIb fibres that did not complete their differentiation. Together, these observations suggest that mice with the mini phenotype have reduced numbers of type IIb fibres in many of their hind-limb muscles, leading to a decrease in mass and an increase in mass-specific aerobic capacity

  20. The relationships between muscle, external, internal and joint mechanical work during normal walking

    PubMed Central

    Sasaki, Kotaro; Neptune, Richard R.; Kautz, Steven A.

    2009-01-01

    Summary Muscle mechanical work is an important biomechanical quantity in human movement analyses and has been estimated using different quantities including external, internal and joint work. The goal of this study was to investigate the relationships between these traditionally used estimates of mechanical work in human walking and to assess whether they can be used as accurate estimates of musculotendon and/or muscle fiber work. A muscle-actuated forward dynamics walking simulation was generated to quantify each of the mechanical work measures. Total joint work (i.e. the time integral of absolute joint power over a full gait cycle) was found to underestimate total musculotendon work due to agonist–antagonist co-contractions, despite the effect of biarticular muscle work and passive joint work, which acted to decrease the underestimation. We did find that when the net passive joint work over the gait cycle is negligible, net joint work (i.e. the time integral of net joint power) was comparable to the net musculotendon work (and net muscle fiber work because net tendon work is zero over a complete gait cycle). Thus, during walking conditions when passive joint work is negligible, net joint work may be used as an estimate of net muscle work. Neither total external nor total internal work (nor their sum) provided a reasonable estimate of total musculotendon work. We conclude that joint work is limited in its ability to estimate musculotendon work, and that external and internal work should not be used as an estimation of musculotendon work. PMID:19218526

  1. Age-related changes in oxidative capacity differ between locomotory muscles and are associated with physical activity behavior

    PubMed Central

    Larsen, Ryan G.; Callahan, Damien M.; Foulis, Stephen A.; Kent-Braun, Jane A.

    2013-01-01

    There is discrepancy in the literature regarding the degree to which old age affects muscle bioenergetics. These discrepancies are likely influenced by several factors, including variations in physical activity (PA) and differences in the muscle group investigated. To test the hypothesis that age may affect muscles differently, we quantified oxidative capacity of tibialis anterior (TA) and vastus lateralis (VL) muscles in healthy, relatively sedentary younger (8 YW, 8 YM; 21–35 years) and older (8 OW, 8 OM; 65–80 years) adults. To investigate the effect of physical activity on muscle oxidative capacity in older adults, we compared older sedentary women to older women with mild-to-moderate mobility impairment and lower physical activity (OIW, n = 7), and older sedentary men with older active male runners (OAM, n = 6). Oxidative capacity was measured in vivo as the rate constant, kPCr, of postcontraction phosphocreatine recovery, obtained by 31P magnetic resonance spectroscopy following maximal isometric contractions. While kPCr was higher in TA of older than activity-matched younger adults (28%; p = 0.03), older adults had lower kPCr in VL (23%; p = 0.04). In OIW compared with OW, kPCr was lower in VL (~45%; p = 0.01), but not different in TA. In contrast, OAM had higher kPCr than OM (p = 0.03) in both TA (41%) and VL (54%). In older adults, moderate-to-vigorous PA was positively associated with kPCr in VL (r = 0.65, p < 0.001) and TA (r = 0.41, p = 0.03). Collectively, these results indicate that age-related changes in oxidative capacity vary markedly between locomotory muscles, and that altered PA behavior may play a role in these changes. PMID:22236246

  2. Sex-Related Difference in Muscle Deoxygenation Responses Between Aerobic Capacity-Matched Elderly Men and Women.

    PubMed

    Takagi, Shun; Kime, Ryotaro; Niwayama, Masatsugu; Osada, Takuya; Murase, Norio; Sakamoto, Shizuo; Katsumura, Toshihito

    2016-01-01

    Muscle O2 dynamics during ramp cycling exercise were compared between aerobic capacity-matched elderly men (n=8, age 65±2 years) and women (n=8, age 66±3 years). Muscle O2 saturation (SmO2) and relative change in deoxygenated (Δdeoxy-Hb) and total hemoglobin concentration (Δtotal-Hb) were monitored continuously during exercise in the vastus lateralis (VL) and gastrocnemius medialis (GM) by near infrared spatial resolved spectroscopy. SmO2 was significantly higher during exercise in women than in men in VL, but not in GM. In VL, Δdeoxy-Hb and Δtotal-Hb were significantly higher in men than in women, especially during high intensity exercise. However, no significant difference was observed in Δdeoxy-Hb or Δtotal-Hb in GM. Sex-related differences in muscle deoxygenation response may be heterogeneous among leg muscles in elderly subjects. PMID:26782195

  3. Effects of Skill Training on Working Memory Capacity

    ERIC Educational Resources Information Center

    Lee, Yuh-shiow; Lu, Min-ju; Ko, Hsiu-ping

    2007-01-01

    In this study we examined the effects of skill training, in particular mental abacus and music training, on working memory. Two groups of participants--children who had received mental abacus training and their controls--participated in Experiment 1. All participants performed the following span tasks: forward digit span, backward digit span,…

  4. Slow-Adhering Stem Cells Derived from Injured Skeletal Muscle Have Improved Regenerative Capacity

    PubMed Central

    Mu, Xiaodong; Xiang, Guosheng; Rathbone, Christopher R.; Pan, Haiying; Bellayr, Ian H.; Walters, Thomas J.; Li, Yong

    2011-01-01

    A wide variety of myogenic cell sources have been used for repair of injured and diseased muscle including muscle stem cells, which can be isolated from skeletal muscle as a group of slow-adhering cells on a collagen-coated surface. The therapeutic use of muscle stem cells for improving muscle regeneration is promising; however, the effect of injury on their characteristics and engraftment potential has yet to be described. In the present study, slow-adhering stem cells (SASCs) from both laceration-injured and control noninjured skeletal muscles in mice were isolated and studied. Migration and proliferation rates, multidifferentiation potentials, and differences in gene expression in both groups of cells were compared in vitro. Results demonstrated that a larger population of SASCs could be isolated from injured muscle than from control noninjured muscle. In addition, SASCs derived from injured muscle demonstrated improved migration, a higher rate of proliferation and multidifferentiation, and increased expression of Notch1, STAT3, Msx1, and MMP2. Moreover, when transplanted into dystrophic muscle in MDX/SCID mice, SASCs from injured muscle generated greater engraftments with a higher capillary density than did SASCs from control noninjured muscle. These data suggest that traumatic injury may modify stem cell characteristics through trophic factors and improve the transplantation potential of SASCs in alleviating skeletal muscle injuries and diseases. PMID:21684246

  5. Can Planning Time Compensate for Individual Differences in Working Memory Capacity?

    ERIC Educational Resources Information Center

    Nielson, Katharine B.

    2014-01-01

    Language learners with high working memory capacity have an advantage, all other factors being equal, during the second language acquisition (SLA) process; therefore, identifying a pedagogical intervention that can compensate for low working memory capacity would be advantageous to language learners and instructors. Extensive research on the…

  6. Mental Capacity and Working Memory in Chemistry: Algorithmic "versus" Open-Ended Problem Solving

    ERIC Educational Resources Information Center

    St Clair-Thompson, Helen; Overton, Tina; Bugler, Myfanwy

    2012-01-01

    Previous research has revealed that problem solving and attainment in chemistry are constrained by mental capacity and working memory. However, the terms mental capacity and working memory come from different theories of cognitive resources, and are assessed using different tasks. The current study examined the relationships between mental…

  7. Validity of Selected Lab and Field Tests of Physical Working Capacity.

    ERIC Educational Resources Information Center

    Burke, Edmund J.

    The validity of selected lab and field tests of physical working capacity was investigated. Forty-four male college students were administered a series of lab and field tests of physical working capacity. Lab tests include a test of maximum oxygen uptake, the PWC 170 test, the Harvard Step Test, the Progressive Pulse Ratio Test, Margaria Test of…

  8. The Contribution of Working Memory to Fluid Reasoning: Capacity, Control, or Both?

    ERIC Educational Resources Information Center

    Chuderski, Adam; Necka, Edward

    2012-01-01

    Fluid reasoning shares a large part of its variance with working memory capacity (WMC). The literature on working memory (WM) suggests that the capacity of the focus of attention responsible for simultaneous maintenance and integration of information within WM, as well as the effectiveness of executive control exerted over WM, determines…

  9. Changes in the Capacity of Visual Working Memory in 5- to 10-Year-Olds

    ERIC Educational Resources Information Center

    Riggs, Kevin J.; McTaggart, James; Simpson, Andrew; Freeman, Richard P. J.

    2006-01-01

    Using the Luck and Vogel change detection paradigm, we sought to investigate the capacity of visual working memory in 5-, 7-, and 10-year-olds. We found that performance on the task improved significantly with age and also obtained evidence that the capacity of visual working memory approximately doubles between 5 and 10 years of age, where it…

  10. Multimedia Learning and Individual Differences: Mediating the Effects of Working Memory Capacity with Segmentation

    ERIC Educational Resources Information Center

    Lusk, Danielle L.; Evans, Amber D.; Jeffrey, Thomas R.; Palmer, Keith R.; Wikstrom, Chris S.; Doolittle, Peter E.

    2009-01-01

    Research in multimedia learning lacks an emphasis on individual difference variables, such as working memory capacity (WMC). The effects of WMC and the segmentation of multimedia instruction were examined by assessing the recall and application of low (n = 66) and high (n = 67) working memory capacity students randomly assigned to either a…

  11. Working Memory Capacity and Mobile Multimedia Learning Environments: Individual Differences in Learning While Mobile

    ERIC Educational Resources Information Center

    Doolittle, Peter E.; Mariano, Gina J.

    2008-01-01

    The present study examined the effects of individual differences in working memory capacity (WMC) on learning from an historical inquiry multimedia tutorial in stationary versus mobile learning environments using a portable digital media player (i.e., iPod). Students with low (n = 44) and high (n = 40) working memory capacity, as measured by the…

  12. Energy expenditure, productivity, and physical work capacity of sugarcane loaders.

    PubMed

    Spurr, G B; Maksud, M G; Barac-Nieto, M

    1977-10-01

    VO2, E and heart rates (fH) were measured in 28 Colombian sugarcane loaders while loading cane and in the laboratory during a VO2max test. Productivity (metric tons-day-1) of the workers was also obtained. During work, VO2 was 1.251-min-1, VE 38.81 min-1, and fH 120 beats-min-1. The subjects worked at 42% of VO2max (6.3 +/- 1.0 kcal-min-1) during the field measurement periods. Energy expenditure was estimated to average 3,281 kcal-24 hr-1. Productivity was higher in men with lower fat content, resting fH and fH at VO2 = 1.25 1-min-1, indicating a positive relationship between productivity and physical fitness. Productivity was not related to age but, since VO2max decreased with age, the relative effort required to maintain productivity increased in the older workers. Efficiency (kg cane loaded-1 VO2-1) and estimated sustained effort (percent VO2max) were not significantly correlated with productivity in this type of discontinuous, moderate work. PMID:910750

  13. 20 CFR 220.126 - Relationship of ability to do work and residual functional capacity.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 20 Employees' Benefits 1 2010-04-01 2010-04-01 false Relationship of ability to do work and... Relationship of ability to do work and residual functional capacity. (a) If the claimant can do his or her previous work (his or her usual work or other applicable past work), the Board will determine he or she...

  14. Blunted angiogenesis and hypertrophy are associated with increased fatigue resistance and unchanged aerobic capacity in old overloaded mouse muscle.

    PubMed

    Ballak, Sam B; Busé-Pot, Tinelies; Harding, Peter J; Yap, Moi H; Deldicque, Louise; de Haan, Arnold; Jaspers, Richard T; Degens, Hans

    2016-04-01

    We hypothesize that the attenuated hypertrophic response in old mouse muscle is (1) partly due to a reduced capillarization and angiogenesis, which is (2) accompanied by a reduced oxidative capacity and fatigue resistance in old control and overloaded muscles, that (3) can be rescued by the antioxidant resveratrol. To investigate this, the hypertrophic response, capillarization, oxidative capacity, and fatigue resistance of m. plantaris were compared in 9- and 25-month-old non-treated and 25-month-old resveratrol-treated mice. Overload increased the local capillary-to-fiber ratio less in old (15 %) than in adult (59 %) muscle (P < 0.05). Although muscles of old mice had a higher succinate dehydrogenase (SDH) activity (P < 0.05) and a slower fiber type profile (P < 0.05), the isometric fatigue resistance was similar in 9- and 25-month-old mice. In both age groups, the fatigue resistance was increased to the same extent after overload (P < 0.01), without a significant change in SDH activity, but an increased capillary density (P < 0.05). Attenuated angiogenesis during overload may contribute to the attenuated hypertrophic response in old age. Neither was rescued by resveratrol supplementation. Changes in fatigue resistance with overload and aging were dissociated from changes in SDH activity, but paralleled those in capillarization. This suggests that capillarization plays a more important role in fatigue resistance than oxidative capacity. PMID:26970774

  15. Happiness increases verbal and spatial working memory capacity where sadness does not: Emotion, working memory and executive control.

    PubMed

    Storbeck, Justin; Maswood, Raeya

    2016-08-01

    The effects of emotion on working memory and executive control are often studied in isolation. Positive mood enhances verbal and impairs spatial working memory, whereas negative mood enhances spatial and impairs verbal working memory. Moreover, positive mood enhances executive control, whereas negative mood has little influence. We examined how emotion influences verbal and spatial working memory capacity, which requires executive control to coordinate between holding information in working memory and completing a secondary task. We predicted that positive mood would improve both verbal and spatial working memory capacity because of its influence on executive control. Positive, negative and neutral moods were induced followed by completing a verbal (Experiment 1) or spatial (Experiment 2) working memory operation span task to assess working memory capacity. Positive mood enhanced working memory capacity irrespective of the working memory domain, whereas negative mood had no influence on performance. Thus, positive mood was more successful holding information in working memory while processing task-irrelevant information, suggesting that the influence mood has on executive control supersedes the independent effects mood has on domain-specific working memory. PMID:25947579

  16. SCD1 activity in muscle increases triglyceride PUFA content, exercise capacity, and PPARδ expression in mice[S

    PubMed Central

    Rogowski, Michael P.; Flowers, Matthew T.; Stamatikos, Alexis D.; Ntambi, James M.; Paton, Chad M.

    2013-01-01

    Stearoyl-CoA desaturase (SCD)1 converts saturated fatty acids into monounsaturated fatty acids. Using muscle overexpression, we sought to determine the role of SCD1 expression in glucose and lipid metabolism and its effects on exercise capacity in mice. Wild-type C57Bl/6 (WT) and SCD1 muscle transgenic (SCD1-Tg) mice were generated, and expression of the SCD1 transgene was restricted to skeletal muscle. SCD1 overexpression was associated with increased triglyceride (TG) content. The fatty acid composition of the muscle revealed a significant increase in polyunsaturated fatty acid (PUFA) content of TG, including linoleate (18:2n6). Untrained SCD1-Tg mice also displayed significantly increased treadmill exercise capacity (WT = 6.6 ± 3 min, Tg = 71.9 ± 9.5 min; P = 0.0009). SCD1-Tg mice had decreased fasting plasma glucose, glucose transporter (GLUT)1 mRNA, fatty acid oxidation, mitochondrial content, and increased peroxisome proliferator-activated receptor (PPAR)δ and Pgc-1 protein expression in skeletal muscle. In vitro studies in C2C12 myocytes revealed that linoleate (18:2n6) and not oleate (18:1n9) caused a 3-fold increase in PPARδ and a 9-fold increase in CPT-1b with a subsequent increase in fat oxidation. The present model suggests that increasing delta-9 desaturase activity of muscle increases metabolic function, exercise capacity, and lipid oxidation likely through increased PUFA content, which increases PPARδ expression and activity. However, the mechanism of action that results in increased PUFA content of SCD1-Tg mice remains to be elucidated. PMID:23918045

  17. Nonverbal auditory working memory: Can music indicate the capacity?

    PubMed

    Jeong, Eunju; Ryu, Hokyoung

    2016-06-01

    Different working memory (WM) mechanisms that underlie words, tones, and timbres have been proposed in previous studies. In this regard, the present study developed a WM test with nonverbal sounds and compared it to the conventional verbal WM test. A total of twenty-five, non-music major, right-handed college students were presented with four different types of sounds (words, syllables, pitches, timbres) that varied from two to eight digits in length. Both accuracy and oxygenated hemoglobin (oxyHb) were measured. The results showed significant effects of number of targets on accuracy and sound type on oxyHb. A further analysis showed prefrontal asymmetry with pitch being processed by the right hemisphere (RH) and timbre by the left hemisphere (LH). These findings suggest a potential for employing musical sounds (i.e., pitch and timbre) as a complementary stimuli for conventional nonverbal WM tests, which can additionally examine its asymmetrical roles in the prefrontal regions. PMID:27031677

  18. Force, work and power output of lower limb muscles during human maximal-effort countermovement jumping.

    PubMed

    Nagano, Akinori; Komura, Taku; Fukashiro, Senshi; Himeno, Ryutaro

    2005-08-01

    The purpose of this study was to simulate human maximal-effort countermovement jumping with a three-dimensional neuromusculoskeletal model. The specific aim was to investigate muscle force, work and power output of major lower limb muscles during the motion. A neuromusculoskeletal model that has nine rigid body segments, 20 degrees of freedom, 32 Hill-type lower limb muscles was developed. The neural activation input signal was represented by a series of step functions with step duration of 0.05 s. The excitation-contraction dynamics of the contractile element, the tissues around the joints to limit the joint range of motion, as well as the foot-ground interaction were implemented. A simulation was started from a standing posture. Optimal pattern of the activation input signal was searched through numerical optimization with a goal of maximizing the height reached by the mass center of body after jumping up. As a result, feasible kinematics, ground reaction force profile and muscle excitation profile were generated. It was found that monoarticular muscles had major contributions of mechanical work and power output, whereas biarticular muscles had minor contributions. Hip adductors, abductors and external rotator muscles were vigorously activated, although their mechanical work and power output was minor because of their limited length change during the motion. Joint flexor muscles such as m. iliopsoas, m. biceps femoris short head and m. tibialis anterior were activated in the beginning of the motion with an effect of facilitating the generation of a countermovement. PMID:15811607

  19. Free [ADP] and aerobic muscle work follow at least second order kinetics in rat gastrocnemius in vivo.

    PubMed

    Cieslar, J H; Dobson, G P

    2000-03-01

    The relationship between free cytosolic [ADP] (and [P(i)]) and steady-state aerobic muscle work in rat gastrocnemius muscle in vivo using (31)P NMR was investigated. Anesthetized rats were ventilated and placed in a custom-built cradle fitted with a force transducer that could be placed into a 7-tesla NMR magnet. Muscle work was induced by supramaximal sciatic nerve stimulation that activated all fibers. Muscles were stimulated at 0.1, 0.2, 0.3, 0.4, 0.5, 0.8, 1.0, and 2.0 Hz until twitch force, phosphocreatine, and P(i) were unchanged between two consecutive spectra acquired in 4-min blocks (8-12 min). Parallel bench experiments were performed to measure total tissue glycogen, lactate, total creatine, and pyruvate in freeze-clamped muscles after 10 min of stimulation at each frequency. Up to 0.5 Hz, there was no significant change in muscle glycogen, lactate, and the lactate/pyruvate ratios between 8-12 min. At 0.8 Hz, there was a 17% fall in glycogen and a 65% rise in the muscle lactate with a concomitant fall in pH. Above this frequency, glycogen fell rapidly, lactate continued to rise, and ATP and pH declined. On the basis of these force and metabolic measurements, we estimated the maximal mitochondrial capacity (V(max)) to be 0.8 Hz. Free [ADP] was then calculated at each submaximal workload from measuring all the reactants of the creatine kinase equilibrium after adjusting the K'(CK) to the muscle temp (30 degrees C), pH, and pMg. We show that ADP (and P(i)) and tension-time integral follow a Hill relationship with at least a second order function. The K(0.5) values for free [ADP] and [P(i)] were 48 microM and 9 mM, respectively. Our data did not fit any form of the Michaelis-Menten equation. We therefore conclude that free cytosolic [ADP] and [P(i)] could potentially control steady-state oxidative phosphorylation in skeletal muscle in vivo. PMID:10692403

  20. Effect of dietary creatine monohydrate supplementation on muscle lipid peroxidation and antioxidant capacity of transported broilers in summer.

    PubMed

    Wang, X F; Zhu, X D; Li, Y J; Liu, Y; Li, J L; Gao, F; Zhou, G H; Zhang, L

    2015-11-01

    This experiment was to evaluate the effect of dietary supplementation with creatine monohydrate (CMH) during the finishing period on the muscle lipid peroxidation and antioxidant capacity of broilers that experienced transport stress in summer. A total of 320 male Arbor Acres broilers (28 d in age) were randomly allotted to 3 dietary treatments including a basal control diet without additional CMH (160 birds), or with 600 (80 birds) or 1,200 mg/kg (80 birds) CMH for 14 d. On the morning of d 42, after an 8-h fast, the birds fed the basal diets were divided into 2 equal groups, and all birds in the 4 groups of 80 birds were transported according to the following protocols: 1) a 0.75-h transport of birds on basal diets (as a lower-stress control group), 2) a 3-h transport of birds on basal diets, 3) a 3-h transport of birds on 600 or 4) 1,200 mg/kg CMH supplementation diets. The results showed that the 3-h transport decreased the concentration of creatine (Cr) in both the pectoralis major (PM) and the tibialis anterior (TA) muscles, increased the concentration of phosphocreatine (PCr) and PCr/Cr ratio in PM muscle, and elevated the concentrations of thiobarbituric acid-reactive substances and the activities of total superoxide dismutase and glutathione peroxidase in both the PM and TA muscles of birds (P < 0.05). In addition, transport also upregulated mRNA expression of avian uncoupling protein and heat shock protein 70 in both the PM and TA muscles, as well as avian peroxisome proliferator-activated receptor γ coactivator-1α in the TA muscle (P < 0.05). Dietary supplementation with 1,200 mg/kg CMH increased the concentrations of Cr and PCr in PM muscle, and Cr in TA muscle than those in the 3-h transport group (P < 0.05). However, contrary to our hypothesis, dietary CMH did not alter the measured parameters in relation to muscle lipid peroxidation and antioxidant capacity affected by 3-h transport (P > 0.05). These results indicate that dietary CMH

  1. Creativity and working memory capacity in sports: working memory capacity is not a limiting factor in creative decision making amongst skilled performers

    PubMed Central

    Furley, Philip; Memmert, Daniel

    2015-01-01

    The goal of the study was to investigate the relationship between domain-general working memory capacity and domain-specific creativity amongst experienced soccer players. We administered the automated operation span task in combination with a domain-specific soccer creativity task to a group of 61 experienced soccer players to address the question whether an athlete’s domain-specific creativity is restricted by their domain-general cognitive abilities (i.e., working memory capacity). Given that previous studies have either found a positive correlation, a negative correlation, or no correlation between working memory capacity and creativity, we analyzed the data in an exploratory manner by following recent recommendations to report effect-size estimations and their precision in form of 95% confidence intervals. The pattern of results provided evidence that domain-general working memory capacity is not associated with creativity in a soccer-specific creativity task. This pattern of results suggests that future research and theorizing on the role of working memory in everyday creative performance needs to distinguish between different types of creative performance while also taking the role of domain-specific experience into account. PMID:25713552

  2. Multivariate Statistical Assessment of Predictors of Firefighters’ Muscular and Aerobic Work Capacity

    PubMed Central

    Lindberg, Ann-Sofie; Oksa, Juha; Antti, Henrik; Malm, Christer

    2015-01-01

    Physical capacity has previously been deemed important for firefighters physical work capacity, and aerobic fitness, muscular strength, and muscular endurance are the most frequently investigated parameters of importance. Traditionally, bivariate and multivariate linear regression statistics have been used to study relationships between physical capacities and work capacities among firefighters. An alternative way to handle datasets consisting of numerous correlated variables is to use multivariate projection analyses, such as Orthogonal Projection to Latent Structures. The first aim of the present study was to evaluate the prediction and predictive power of field and laboratory tests, respectively, on firefighters’ physical work capacity on selected work tasks. Also, to study if valid predictions could be achieved without anthropometric data. The second aim was to externally validate selected models. The third aim was to validate selected models on firefighters’ and on civilians’. A total of 38 (26 men and 12 women) + 90 (38 men and 52 women) subjects were included in the models and the external validation, respectively. The best prediction (R2) and predictive power (Q2) of Stairs, Pulling, Demolition, Terrain, and Rescue work capacities included field tests (R2 = 0.73 to 0.84, Q2 = 0.68 to 0.82). The best external validation was for Stairs work capacity (R2 = 0.80) and worst for Demolition work capacity (R2 = 0.40). In conclusion, field and laboratory tests could equally well predict physical work capacities for firefighting work tasks, and models excluding anthropometric data were valid. The predictive power was satisfactory for all included work tasks except Demolition. PMID:25775243

  3. Increased Muscle Sympathetic Nerve Activity and Impaired Executive Performance Capacity in Obstructive Sleep Apnea

    PubMed Central

    Goya, Thiago T.; Silva, Rosyvaldo F.; Guerra, Renan S.; Lima, Marta F.; Barbosa, Eline R.F.; Cunha, Paulo Jannuzzi; Lobo, Denise M.L.; Buchpiguel, Carlos A.; Busatto-Filho, Geraldo; Negrão, Carlos E.; Lorenzi-Filho, Geraldo; Ueno-Pardi, Linda M.

    2016-01-01

    Study Objectives: To investigate muscle sympathetic nerve activity (MSNA) response and executive performance during mental stress in obstructive sleep apnea (OSA). Methods: Individuals with no other comorbidities (age = 52 ± 1 y, body mass index = 29 ± 0.4, kg/m2) were divided into two groups: (1) control (n = 15) and (2) untreated OSA (n = 20) defined by polysomnography. Mini-Mental State of Examination (MMSE) and Inteligence quocient (IQ) were assessed. Heart rate (HR), blood pressure (BP), and MSNA (microneurography) were measured at baseline and during 3 min of the Stroop Color Word Test (SCWT). Sustained attention and inhibitory control were assessed by the number of correct answers and errors during SCWT. Results: Control and OSA groups (apnea-hypopnea index, AHI = 8 ± 1 and 47 ± 1 events/h, respectively) were similar in age, MMSE, and IQ. Baseline HR and BP were similar and increased similarly during SCWT in control and OSA groups. In contrast, baseline MSNA was higher in OSA compared to controls. Moreover, MSNA significantly increased in the third minute of SCWT in OSA, but remained unchanged in controls (P < 0.05). The number of correct answers was lower and the number of errors was significantly higher during the second and third minutes of SCWT in the OSA group (P < 0.05). There was a significant correlation (P < 0.01) between the number of errors in the third minute of SCWT with AHI (r = 0.59), arousal index (r = 0.55), and minimum O2 saturation (r = −0.57). Conclusions: As compared to controls, MSNA is increased in patients with OSA at rest, and further significant MSNA increments and worse executive performance are seen during mental stress. Clinical Trial Registration: URL: http://www.clinicaltrials.gov, registration number: NCT002289625. Citation: Goya TT, Silva RF, Guerra RS, Lima MF, Barbosa ER, Cunha PJ, Lobo DM, Buchpiguel CA, Busatto-Filho G, Negrão CE, Lorenzi-Filho G, Ueno-Pardi LM. Increased muscle sympathetic nerve activity and

  4. Relation between Working Memory Capacity and Auditory Stream Segregation in Children with Auditory Processing Disorder

    PubMed Central

    Lotfi, Yones; Mehrkian, Saiedeh; Moossavi, Abdollah; Zadeh, Soghrat Faghih; Sadjedi, Hamed

    2016-01-01

    Background: This study assessed the relationship between working memory capacity and auditory stream segregation by using the concurrent minimum audible angle in children with a diagnosed auditory processing disorder (APD). Methods: The participants in this cross-sectional, comparative study were 20 typically developing children and 15 children with a diagnosed APD (age, 9–11 years) according to the subtests of multiple-processing auditory assessment. Auditory stream segregation was investigated using the concurrent minimum audible angle. Working memory capacity was evaluated using the non-word repetition and forward and backward digit span tasks. Nonparametric statistics were utilized to compare the between-group differences. The Pearson correlation was employed to measure the degree of association between working memory capacity and the localization tests between the 2 groups. Results: The group with APD had significantly lower scores than did the typically developing subjects in auditory stream segregation and working memory capacity. There were significant negative correlations between working memory capacity and the concurrent minimum audible angle in the most frontal reference location (0° azimuth) and lower negative correlations in the most lateral reference location (60° azimuth) in the children with APD. Conclusion: The study revealed a relationship between working memory capacity and auditory stream segregation in children with APD. The research suggests that lower working memory capacity in children with APD may be the possible cause of the inability to segregate and group incoming information. PMID:26989281

  5. Models provide specificity: Testing a proposed mechanism of visual working memory capacity development

    PubMed Central

    Simmering, Vanessa R.; Patterson, A. Rebecca

    2012-01-01

    Numerous studies have established that visual working memory has a limited capacity, and that capacity increases during childhood. However, debate continues over the source of capacity limits and its developmental increase. Simmering (2008) adapted a computational model of spatial cognitive development, the Dynamic Field Theory, to explain not only the source of capacity limitations but also the developmental mechanism. According to the model, capacity is limited by the balance between excitation and inhibition that maintains multiple neural representations simultaneously. Moreover, development is implemented according to the Spatial Precision Hypothesis, which proposes that excitatory and inhibitory connections strengthen throughout early childhood. Critically, these changes in connectivity result in increasing precision and stability of neural representations over development. Here we test this developmental mechanism by probing children’s memory in a single-item change detection task. Results confirmed the model’s predictions, providing further support for this account of visual working memory capacity development. PMID:23204645

  6. Fetal muscle gene transfer is not enhanced by an RGD capsid modification to high-capacity adenoviral vectors.

    PubMed

    Bilbao, R; Reay, D P; Hughes, T; Biermann, V; Volpers, C; Goldberg, L; Bergelson, J; Kochanek, S; Clemens, P R

    2003-10-01

    High levels of alpha(v) integrin expression by fetal muscle suggested that vector re-targeting to integrins could enhance adenoviral vector-mediated transduction, thereby increasing safety and efficacy of muscle gene transfer in utero. High-capacity adenoviral (HC-Ad) vectors modified by an Arg-Gly-Asp (RGD) peptide motif in the HI loop of the adenoviral fiber (RGD-HC-Ad) have demonstrated efficient gene transfer through binding to alpha(v) integrins. To test integrin targeting of HC-Ad vectors for fetal muscle gene transfer, we compared unmodified and RGD-modified HC-Ad vectors. In vivo, unmodified HC-Ad vector transduced fetal mouse muscle with four-fold higher efficiency compared to RGD-HC-Ad vector. Confirming that the difference was due to muscle cell autonomous factors and not mechanical barriers, transduction of primary myogenic cells isolated from murine fetal muscle in vitro demonstrated a three-fold better transduction by HC-Ad vector than by RGD-HC-Ad vector. We hypothesized that the high expression level of coxsackievirus and adenovirus receptor (CAR), demonstrated in fetal muscle cells both in vitro and in vivo, was the crucial variable influencing the relative transduction efficiencies of HC-Ad and RGD-HC-Ad vectors. To explore this further, we studied transduction by HC-Ad and RGD-HC-Ad vectors in paired cell lines that expressed alpha(v) integrins and differed only by the presence or absence of CAR expression. The results increase our understanding of factors that will be important for retargeting HC-Ad vectors to enhance gene transfer to fetal muscle. PMID:12960972

  7. A 9-wk docosahexaenoic acid-enriched supplementation improves endurance exercise capacity and skeletal muscle mitochondrial function in adult rats.

    PubMed

    Le Guen, Marie; Chaté, Valérie; Hininger-Favier, Isabelle; Laillet, Brigitte; Morio, Béatrice; Pieroni, Gérard; Schlattner, Uwe; Pison, Christophe; Dubouchaud, Hervé

    2016-02-01

    Decline in skeletal muscle mass and function starts during adulthood. Among the causes, modifications of the mitochondrial function could be of major importance. Polyunsaturated fatty (ω-3) acids have been shown to play a role in intracellular functions. We hypothesize that docosahexaenoic acid (DHA) supplementation could improve muscle mitochondrial function that could contribute to limit the early consequences of aging on adult muscle. Twelve-month-old male Wistar rats were fed a low-polyunsaturated fat diet and were given DHA (DHA group) or placebo (control group) for 9 wk. Rats from the DHA group showed a higher endurance capacity (+56%, P < 0.05) compared with control animals. Permeabilized myofibers from soleus muscle showed higher O2 consumptions (P < 0.05) in the DHA group compared with the control group, with glutamate-malate as substrates, both in basal conditions (i.e., state 2) and under maximal conditions (i.e., state 3, using ADP), along with a higher apparent Km for ADP (P < 0.05). Calcium retention capacity of isolated mitochondria was lower in DHA group compared with the control group (P < 0.05). Phospho-AMPK/AMPK ratio and PPARδ mRNA content were higher in the DHA group compared with the control group (P < 0.05). Results showed that DHA enhanced endurance capacity in adult animals, a beneficial effect potentially resulting from improvement in mitochondrial function, as suggested by our results on permeabilized fibers. DHA supplementation could be of potential interest for the muscle function in adults and for fighting the decline in exercise tolerance with age that could imply energy-sensing pathway, as suggested by changes in phospho-AMPK/AMPK ratio. PMID:26646102

  8. Skeletal myofiber VEGF regulates contraction-induced perfusion and exercise capacity but not muscle capillarity in adult mice.

    PubMed

    Knapp, Amy E; Goldberg, Daniel; Delavar, Hamid; Trisko, Breanna M; Tang, Kechun; Hogan, Michael C; Wagner, Peter D; Breen, Ellen C

    2016-07-01

    A single bout of exhaustive exercise signals expression of vascular endothelial growth factor (VEGF) in the exercising muscle. Previous studies have reported that mice with life-long deletion of skeletal myofiber VEGF have fewer capillaries and a severe reduction in endurance exercise. However, in adult mice, VEGF gene deletion conditionally targeted to skeletal myofibers limits exercise capacity without evidence of capillary regression. To explain this, we hypothesized that adult skeletal myofiber VEGF acutely regulates skeletal muscle perfusion during muscle contraction. A tamoxifen-inducible skeletal myofiber-specific VEGF gene deletion mouse (skmVEGF-/-) was used to reduce skeletal muscle VEGF protein by 90% in adult mice. Three weeks after inducing deletion of the skeletal myofiber VEGF gene, skmVEGF-/- mice exhibited diminished maximum running speed (-10%, P < 0.05) and endurance capacity (-47%; P < 0.05), which did not persist after 8 wk. In skmVEGF-/- mice, gastrocnemius complex time to fatigue measured in situ was 71% lower than control mice. Contraction-induced perfusion measured by optical imaging during a period of electrically stimulated muscle contraction was 85% lower in skmVEGF-/- than control mice. No evidence of capillary rarefication was detected in the soleus, gastrocnemius, and extensor digitorum longus (EDL) up to 8 wk after tamoxifen-induced VEGF ablation, and contractility and fatigue resistance of the soleus measured ex vivo were also unchanged. The force-frequency of the EDL showed a small right shift, but fatigue resistance did not differ between EDL from control and skmVEGF-/- mice. These data suggest myofiber VEGF is required for regulating perfusion during periods of contraction and may in this manner affect endurance capacity. PMID:27225953

  9. Effect of low-voltage electrical stimulation after dressing on color stability and water holding capacity of bovine longissimus muscle.

    PubMed

    Li, Chunbao; Li, Jing; Li, Xin; Hviid, Marchen; Lundström, Kerstin

    2011-07-01

    The effect of low voltage electrical stimulation after dressing (ES) on color stability and water holding capacity (WHC) of beef was investigated. Nine Swedish red cattle were slaughtered and the left side was electrically stimulated (80 V, 35 s) approximately 30 min after stunning, whereas the other side was not treated and used as control. Color and its stability, WHC, and protein solubility were evaluated on longissimus lumborum muscles from the two sides. ES produced a brighter red color at 24h mainly by increasing the oxygenation capacity of myoglobin (P<0.01), which was attenuated by postmortem aging. ES did not affect WHC, protein solubility and color stability (P>0.05). Therefore, this technology could accelerate meat tenderization without any negative effect on commercial attributes, such as color or drip of bovine longissimus muscle. PMID:21382673

  10. Models Provide Specificity: Testing a Proposed Mechanism of Visual Working Memory Capacity Development

    ERIC Educational Resources Information Center

    Simmering, Vanessa R.; Patterson, Rebecca

    2012-01-01

    Numerous studies have established that visual working memory has a limited capacity that increases during childhood. However, debate continues over the source of capacity limits and its developmental increase. Simmering (2008) adapted a computational model of spatial cognitive development, the Dynamic Field Theory, to explain not only the source…

  11. Effective Visual Working Memory Capacity: An Emergent Effect from the Neural Dynamics in an Attractor Network

    PubMed Central

    Dempere-Marco, Laura; Melcher, David P.; Deco, Gustavo

    2012-01-01

    The study of working memory capacity is of outmost importance in cognitive psychology as working memory is at the basis of general cognitive function. Although the working memory capacity limit has been thoroughly studied, its origin still remains a matter of strong debate. Only recently has the role of visual saliency in modulating working memory storage capacity been assessed experimentally and proved to provide valuable insights into working memory function. In the computational arena, attractor networks have successfully accounted for psychophysical and neurophysiological data in numerous working memory tasks given their ability to produce a sustained elevated firing rate during a delay period. Here we investigate the mechanisms underlying working memory capacity by means of a biophysically-realistic attractor network with spiking neurons while accounting for two recent experimental observations: 1) the presence of a visually salient item reduces the number of items that can be held in working memory, and 2) visually salient items are commonly kept in memory at the cost of not keeping as many non-salient items. Our model suggests that working memory capacity is determined by two fundamental processes: encoding of visual items into working memory and maintenance of the encoded items upon their removal from the visual display. While maintenance critically depends on the constraints that lateral inhibition imposes to the mnemonic activity, encoding is limited by the ability of the stimulated neural assemblies to reach a sufficiently high level of excitation, a process governed by the dynamics of competition and cooperation among neuronal pools. Encoding is therefore contingent upon the visual working memory task and has led us to introduce the concept of effective working memory capacity (eWMC) in contrast to the maximal upper capacity limit only reached under ideal conditions. PMID:22952608

  12. Effective visual working memory capacity: an emergent effect from the neural dynamics in an attractor network.

    PubMed

    Dempere-Marco, Laura; Melcher, David P; Deco, Gustavo

    2012-01-01

    The study of working memory capacity is of outmost importance in cognitive psychology as working memory is at the basis of general cognitive function. Although the working memory capacity limit has been thoroughly studied, its origin still remains a matter of strong debate. Only recently has the role of visual saliency in modulating working memory storage capacity been assessed experimentally and proved to provide valuable insights into working memory function. In the computational arena, attractor networks have successfully accounted for psychophysical and neurophysiological data in numerous working memory tasks given their ability to produce a sustained elevated firing rate during a delay period. Here we investigate the mechanisms underlying working memory capacity by means of a biophysically-realistic attractor network with spiking neurons while accounting for two recent experimental observations: 1) the presence of a visually salient item reduces the number of items that can be held in working memory, and 2) visually salient items are commonly kept in memory at the cost of not keeping as many non-salient items. Our model suggests that working memory capacity is determined by two fundamental processes: encoding of visual items into working memory and maintenance of the encoded items upon their removal from the visual display. While maintenance critically depends on the constraints that lateral inhibition imposes to the mnemonic activity, encoding is limited by the ability of the stimulated neural assemblies to reach a sufficiently high level of excitation, a process governed by the dynamics of competition and cooperation among neuronal pools. Encoding is therefore contingent upon the visual working memory task and has led us to introduce the concept of effective working memory capacity (eWMC) in contrast to the maximal upper capacity limit only reached under ideal conditions. PMID:22952608

  13. The sensory strength of voluntary visual imagery predicts visual working memory capacity.

    PubMed

    Keogh, Rebecca; Pearson, Joel

    2014-01-01

    How much we can actively hold in mind is severely limited and differs greatly from one person to the next. Why some individuals have greater capacities than others is largely unknown. Here, we investigated why such large variations in visual working memory (VWM) capacity might occur, by examining the relationship between visual working memory and visual mental imagery. To assess visual working memory capacity participants were required to remember the orientation of a number of Gabor patches and make subsequent judgments about relative changes in orientation. The sensory strength of voluntary imagery was measured using a previously documented binocular rivalry paradigm. Participants with greater imagery strength also had greater visual working memory capacity. However, they were no better on a verbal number working memory task. Introducing a uniform luminous background during the retention interval of the visual working memory task reduced memory capacity, but only for those with strong imagery. Likewise, for the good imagers increasing background luminance during imagery generation reduced its effect on subsequent binocular rivalry. Luminance increases did not affect any of the subgroups on the verbal number working memory task. Together, these results suggest that luminance was disrupting sensory mechanisms common to both visual working memory and imagery, and not a general working memory system. The disruptive selectivity of background luminance suggests that good imagers, unlike moderate or poor imagers, may use imagery as a mnemonic strategy to perform the visual working memory task. PMID:25301015

  14. Flight capacity of Bactrocera dorsalis (Diptera: Tephritidae) adult females based on flight mill studies and flight muscle ultrastructure.

    PubMed

    Chen, Min; Chen, Peng; Ye, Hui; Yuan, Ruiling; Wang, Xiaowei; Xu, Jin

    2015-01-01

    The oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), is considered a major economic threat in many regions worldwide. To better comprehend flight capacity of B. dorsalis and its physiological basis, a computer-monitored flight mill was used to study flight capacity of B. dorsalis adult females of various ages, and the changes of its flight muscle ultrastructures were studied by transmission electron microscopy. The flight capacity (both speed and distance) changed significantly with age of B. dorsalis female adults, peaking at about 15 d; the myofibril diameter of the flight muscle of test insects at 15-d old was the longest, up to 1.56 µm, the sarcomere length at 15-d old was the shortest, averaging at 1.37 µm, volume content of mitochondria of flight muscle at 15-d old reached the peak, it was 32.64%. This study provides the important scientific data for better revealing long-distance movement mechanism of B. dorsalis. PMID:26450591

  15. Flight Capacity of Bactrocera dorsalis (Diptera: Tephritidae) Adult Females Based on Flight Mill Studies and Flight Muscle Ultrastructure

    PubMed Central

    Chen, Peng; Yuan, Ruiling; Wang, Xiaowei; Xu, Jin

    2015-01-01

    The oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), is considered a major economic threat in many regions worldwide. To better comprehend flight capacity of B. dorsalis and its physiological basis, a computer-monitored flight mill was used to study flight capacity of B. dorsalis adult females of various ages, and the changes of its flight muscle ultrastructures were studied by transmission electron microscopy. The flight capacity (both speed and distance) changed significantly with age of B. dorsalis female adults, peaking at about 15 d; the myofibril diameter of the flight muscle of test insects at 15-d old was the longest, up to 1.56 µm, the sarcomere length at 15-d old was the shortest, averaging at 1.37 µm, volume content of mitochondria of flight muscle at 15-d old reached the peak, it was 32.64%. This study provides the important scientific data for better revealing long-distance movement mechanism of B. dorsalis. PMID:26450591

  16. The effect of glycogen depletion and supercompensation on the physical working capacity at the fatigue threshold.

    PubMed

    Housh, T J; deVries, H A; Johnson, G O; Evans, S A; Tharp, G D; Housh, D J; Hughes, R J

    1990-01-01

    The purpose of this investigation was to determine the effect of glycogen depletion and supercompensation on the physical working capacity at the fatigue threshold (PWCFT). Ten adult males (mean age 23 years, SD 3) volunteered as subjects for this study. During the first laboratory visit the subjects performed a maximal bicycle ergometer test for the determination of maximum oxygen consumption (VO2max). Between 48 and 72 h later, the subjects pedaled to exhaustion at a power output which corresponded to a mean of 76% of VO2max (range, 72-80%) for the purpose of glycogen depletion. For the next 3 days, the subjects were fed a 10.5 MJ.day-1 low carbohydrate diet which consisted of 7.5% carbohydrates, 22.0% protein and 70.5% fat. The subjects then performed an incremental cycle ergometer test to the onset of fatigue or PWCFT, which was estimated from integrated electromyographic voltages of the vastus lateralis muscle. For the next 3 days the subjects were fed a 10.5 MJ high carbohydrate diet which consisted of 72.2% carbohydrates, 12.4% protein and 15.4% fats for the purpose of glycogen supercompensation. The subjects then performed a second PWCFT test. A paired t-test indicated that there was no significant (p greater than 0.05) difference between the means of the PWCFT values (depletion 246 W, SD 30; supercompensation 265 W, SD 28) and they were highly correlated at r = 0.884. The results of this investigation suggested that the methods commonly used to affect glycogen depletion or supercompensation had no effect on PWCFT. PMID:2369912

  17. Distinct Transfer Effects of Training Different Facets of Working Memory Capacity

    ERIC Educational Resources Information Center

    von Bastian, Claudia C.; Oberauer, Klaus

    2013-01-01

    The impact of working memory training on a broad set of transfer tasks was examined. Each of three groups of participants trained one specific functional category of working memory capacity: storage and processing, relational integration, and supervision. A battery comprising tests to measure working memory, task shifting, inhibition, and…

  18. Muscle force, work and cost: a novel technique to revisit the Fenn effect.

    PubMed

    Ortega, Justus O; Lindstedt, Stan L; Nelson, Frank E; Jubrias, Sharon A; Kushmerick, Martin J; Conley, Kevin E

    2015-07-01

    Muscle produces force by forming cross-bridges, using energy released from ATP. While the magnitude and duration of force production primarily determine the energy requirement, nearly a century ago Fenn observed that muscle shortening or lengthening influenced energetic cost of contraction. When work is done by the muscle, the energy cost is increased and when work is done on the muscle the energy cost is reduced. However, the magnitude of the 'Fenn effect' and its mirror ('negative Fenn effect') have not been quantitatively resolved. We describe a new technique coupling magnetic resonance spectroscopy with an in vivo force clamp that can directly quantify the Fenn effect [E=I+W, energy liberated (E) equals the energy cost of isometric force production (I) plus the work done (W)] and the negative Fenn effect (E=I-W) for one muscle, the first dorsal interosseous (FDI). ATP cost was measured during a series of contractions, each of which occurred at a constant force and for a constant duration, thus constant force-time integral (FTI). In all subjects, as the FTI increased with load, there was a proportional linear increase in energy cost. In addition, the cost of producing force greatly increased when the muscle shortened, and was slightly reduced during lengthening contraction. These results, though limited to a single muscle, contraction velocity and muscle length change, do quantitatively support the Fenn effect. We speculate that they also suggest that an elastic element within the FDI muscle functions to preserve the force generated within the cross-bridges. PMID:25964423

  19. Plantar flexor moment arm and muscle volume predict torque-generating capacity in young men

    PubMed Central

    Baxter, Josh R.

    2013-01-01

    Muscle volume is known to correlate with maximal joint torque in humans, but the role of muscle moment arm in determining maximal torque is less clear. Moderate correlations have been reported between maximal isometric knee extensor torque and knee extensor moment arm, but no such observations have been made for the ankle joint. It has been suggested that smaller muscle moment arms may enhance force generation at high rates of joint rotation, but this has not yet been observed for ankle muscles in vivo. The purpose of the present study was to correlate plantar flexor moment arm and plantar flexor muscle volume with maximal plantar flexor torque measured at different rates of plantar flexion. Magnetic resonance imaging was used to quantify the plantar flexor moment arm and muscle volume of the posterior compartment in 20 healthy young men. Maximal plantar flexor torque was measured isometrically and at three plantar flexion speeds using an isokinetic dynamometer. Plantar flexor torque was significantly correlated with muscle volume (0.222 < R2 < 0.322) and with muscle moment arm at each speed (0.323 < R2 < 0.494). While muscle volume was strongly correlated with body mass and stature, moment arm was not. The slope of the torque-moment arm regression line decreased as the rate of joint rotation increased, indicating that subjects with small moment arms experienced smaller reductions in torque at high speeds. The findings of this study suggest that plantar flexor moment arm is a determinant of joint strength that is at least as important as muscle size. PMID:24371016

  20. Working memory capacity and spontaneous emotion regulation: high capacity predicts self-enhancement in response to negative feedback.

    PubMed

    Schmeichel, Brandon J; Demaree, Heath A

    2010-10-01

    Although previous evidence suggests that working memory capacity (WMC) is important for success at emotion regulation, that evidence may reveal simply that people with higher WMC follow instructions better than those with lower WMC. The present study tested the hypothesis that people with higher WMC more effectively engage in spontaneous emotion regulation following negative feedback, relative to those with lower WMC. Participants were randomly assigned to receive either no feedback or negative feedback about their emotional intelligence. They then completed a disguised measure of self-enhancement and a self-report measure of affect. Experimental condition and WMC interacted such that higher WMC predicted more self-enhancement and less negative affect following negative feedback. This research provides novel insight into the consequences of individual differences in WMC and illustrates that cognitive capacity may facilitate the spontaneous self-regulation of emotion. PMID:21038959

  1. Precision requirements do not affect the allocation of visual working memory capacity.

    PubMed

    He, Xu; Zhang, Weiwei; Li, Cuihong; Guo, Chunyan

    2015-03-30

    There has been a debate about whether allocation of visual working memory (VWM) capacity was flexible. One of the key points about this issue is whether complexity has an effect on the capacity, and one of the critical features of complex objects is higher requirements on the encoding precision than simple objects. Thus we investigated the influence of precision requirements on the allocation of VWM capacity resources, by comparing VWM capacity under different levels of sample-test similarity in a change-detection task. If the VWM capacity is limited by a fixed number of items, then the capacity should not be affected by precision requirements; however, if the capacity is allocated flexibly, then precision requirements should influence the capacity. Cowan's K and amplitude of contralateral delay activity (CDA) were used as behavioral and neurophysiological measures of VWM capacity, respectively. Cowan's K for high-precision discrimination was calculated on the basis of the accuracy of a small number of large-change trials inserted into high-precision blocks. This approach avoided the confounder of different test-phase difficulties between the low- and high-precision conditions and controlled for errors during the test phase. The results showed no effect of precision requirements on VWM capacity. However, analysis of the late positive component (LPC) amplitude indicated that higher precision requirements indeed caused more top-down control over VWM retention. These results support the hypothesis that VWM is limited by a fixed number of items. PMID:25625356

  2. Comparison of Orbicularis Oculi Muscle Activity during Computer Work with Single and Dual Monitors

    PubMed Central

    Yoo, Won-gyu

    2014-01-01

    [Purpose] This study compared the orbicularis oculi muscle activity during computer work with single and dual monitors. [Subjects] Ten computer workers 22–27 years of age were included in this study. [Methods] Subjects performed computer work with single or dual monitors, and the activity of the right orbicularis oculi muscle was measured with a MP150 system. [Results] The muscle activity of the orbicularis oculi under condition 1 was significantly decreased compared with that under conditions 2 or 3. The muscle activity of the orbicularis oculi under condition 3 was significantly increased compared with that under condition 2. [Conclusion] The present study found that the use of dual monitors increased orbicularis oculi activity; therefore, to decrease eye fatigue in computer users, computer workstations that use either a single monitor, or identical monitors from the same manufacturer in a dual setup, are recommended. PMID:25435706

  3. Influence of muscle temperature during fatiguing work with the first dorsal interosseous muscle in man: a 31P-NMR spectroscopy study.

    PubMed

    Wade, A J; Broadhead, M W; Cady, E B; Llewelyn, M E; Tong, H N; Newham, D J

    2000-02-01

    Six healthy subjects rapidly lifted and lowered a small (250 g) weight with the first dorsal interosseous muscle (FDI) of one hand while the work performed was recorded continuously until fatigue (defined as losing the ability to continue lifting). Work was recorded in units of chart recorder trace displacement from baseline (centimeters) as an isotonic transducer followed the movement of the weight. In all experiments, the temperature of the hand was first adjusted by immersion in a controlled-temperature water bath. In the warmest condition, the skin surface temperature over the FDI was 30.5(0.30) degrees C [mean (SE)]. After moderate cooling, this surface temperature was 21.5(0.16) degrees C. Cooling significantly reduced the time taken to reach fatigue and more than halved the work capacity. An intermediate degree of cooling was also used in four subjects, showing that most of the effects seen were changing incrementally. Before work, and at fatigue, intracellular metabolic conditions in the FDI were studied by phosphorus nuclear magnetic resonance (31P-NMR) spectroscopy, with occlusion of the blood flow maintained during measurements. The mean intracellular pH of the FDI was also calculated. The changes observed were all consistent with the fact that intense work requires energy which must be derived largely from intracellular stores of phosphocreatine and glycogen. Less work made less demand upon reserves, and created lower concentrations of waste products and by-products. The observations did not, however, allow us to explain why fatigue occurred at a particular point or why work capacity was reduced by cooling. PMID:10638378

  4. Energetic costs of producing muscle work and force in a cyclical human bouncing task

    PubMed Central

    Kuo, Arthur D.

    2011-01-01

    Muscles expend energy to perform active work during locomotion, but they may also expend significant energy to produce force, for example when tendons perform much of the work passively. The relative contributions of work and force to overall energy expenditure are unknown. We therefore measured the mechanics and energetics of a cyclical bouncing task, designed to control for work and force. We hypothesized that near bouncing resonance, little work would be performed actively by muscle, but the cyclical production of force would cost substantial metabolic energy. Human subjects (n = 9) bounced vertically about the ankles at inversely proportional frequencies (1–4 Hz) and amplitudes (15–4 mm), such that the overall rate of work performed on the body remained approximately constant (0.30 ± 0.06 W/kg), but the forces varied considerably. We used parameter identification to estimate series elasticity of the triceps surae tendon, as well as the work performed actively by muscle and passively by tendon. Net metabolic energy expenditure for bouncing at 1 Hz was 1.15 ± 0.31 W/kg, attributable mainly to active muscle work with an efficiency of 24 ± 3%. But at 3 Hz (near resonance), most of the work was performed passively, so that active muscle work could account for only 40% of the net metabolic rate of 0.76 ± 0.28 W/kg. Near resonance, a cost for cyclical force that increased with both amplitude and frequency of force accounted for at least as much of the total energy expenditure as a cost for work. Series elasticity reduces the need for active work, but energy must still be expended for force production. PMID:21212245

  5. The up and down bobbing of human walking: a compromise between muscle work and efficiency

    PubMed Central

    Massaad, Firas; Lejeune, Thierry M; Detrembleur, Christine

    2007-01-01

    Human walking has a peculiar straight-legged style. Consequently, the body's centre of mass (CM) moves up and down with each step, which is noticeable in their up and down head bobbing while walking. This vertical CM movement enables humans to save energy via a pendulum-like mechanism but is probably a relatively recent locomotor innovation insofar as earliest bipeds may have walked flexed and flat. We investigated the mechanics, energetics, muscle efficiency and optimization of human walking by decreasing and increasing the vertical CM displacement (flat and bouncy walking) in comparison to normal walking at six speeds (1–6 km h−1). In both flat and bouncy walking, the pendular mechanism was reduced and the energy cost was increased. However, this increase was unexpectedly much sharper in flat walking where muscles provided normal mechanical work but with a decrease in muscle efficiency. In bouncy walking, muscles provided extra mechanical work in an efficient way. Our results showed that not only do humans bob up and down in normal walking to save energy via a pendulum-like mechanism but also to make their muscles work efficiently. Actually, walking flat makes the muscles work in unfavourable conditions that waste energy. Furthermore, we are still close to a flat CM displacement relative to our current ability to change this displacement, which suggests that reducing vertical CM displacement is indeed important but only to certain limits. Evolution may ultimately have chosen the best compromise between flat locomotion that requires little work to move and bouncy locomotion that improves muscle efficiency to minimize energy consumption. PMID:17463048

  6. High Intensity Exercise in Multiple Sclerosis: Effects on Muscle Contractile Characteristics and Exercise Capacity, a Randomised Controlled Trial

    PubMed Central

    Vandenabeele, Frank; Grevendonk, Lotte; Verboven, Kenneth; Hansen, Dominique

    2015-01-01

    Introduction Low-to-moderate intensity exercise improves muscle contractile properties and endurance capacity in multiple sclerosis (MS). The impact of high intensity exercise remains unknown. Methods Thirty-four MS patients were randomized into a sedentary control group (SED, n = 11) and 2 exercise groups that performed 12 weeks of a high intensity interval (HITR, n = 12) or high intensity continuous cardiovascular training (HCTR, n = 11), both in combination with resistance training. M.vastus lateralis fiber cross sectional area (CSA) and proportion, knee-flexor/extensor strength, body composition, maximal endurance capacity and self-reported physical activity levels were assessed before and after 12 weeks. Results Compared to SED, 12 weeks of high intensity exercise increased mean fiber CSA (HITR: +21±7%, HCTR: +23±5%). Furthermore, fiber type I CSA increased in HCTR (+29±6%), whereas type II (+23±7%) and IIa (+23±6%,) CSA increased in HITR. Muscle strength improved in HITR and HCTR (between +13±7% and +45±20%) and body fat percentage tended to decrease (HITR: -3.9±2.0% and HCTR: -2.5±1.2%). Furthermore, endurance capacity (Wmax +21±4%, time to exhaustion +24±5%, VO2max +17±5%) and lean tissue mass (+1.4±0.5%) only increased in HITR. Finally self-reported physical activity levels increased 73±19% and 86±27% in HCTR and HITR, respectively. Conclusion High intensity cardiovascular exercise combined with resistance training was safe, well tolerated and improved muscle contractile characteristics and endurance capacity in MS. Trial Registration ClinicalTrials.gov NCT01845896 PMID:26418222

  7. Correlation Between Working Capacity and APDL in Middle-Aged and Elderly People with Intellectual Impairment

    PubMed Central

    Nakajima, Kazuo

    1999-01-01

    In this study we investigated the correlation between working capacity and APDL of middle-aged and elderly residents of welfare homes for the intellectually retarded. The subjects were 313 intellectually retarded people over 35 years old. The subjects were chosen from residents of four welfare institutions and job-placement centers for intellectually retarded people in Otaru, Hokkaido. Personal attributes, working capacity, and APDL were investigated in each subject. The items of personal attributes were: gender, chronological age, severity of intellectual impairment, and presence/absence of Down's syndrome. Working capacity was evaluated according to the 6 items. APDL was evaluated according to the 51 items. For statistical analysis of the working capacity of the subjects, the variables were summarized using principal component analysis and scored. Next, a search was made for the common factors in the 51 items of APDL using the principal component method. Finally, the correlation between working capacity and APDL was investigated by multiple regression analysis, with the obtained composite scores as dependent variables and the scores of APDL factors extracted by principal component analysis as independent variables. The following three factors were selected for the subjects: health management, outdoor movement and social activity. The multiple correlation coefficient using these three factors was R=0.63 (F=55.20, p<0.01). This indicates the necessity, from the viewpoints of prevention of senility, to focus not only on the decrease in working capacity of aging residents with intellectual impairment in welfare institutions but to establish various countermeasures based on the interrelationship between working capacity and APDL. PMID:25792909

  8. Mitochondrial coupling and capacity of oxidative phosphorylation in skeletal muscle of Inuit and Caucasians in the arctic winter.

    PubMed

    Gnaiger, E; Boushel, R; Søndergaard, H; Munch-Andersen, T; Damsgaard, R; Hagen, C; Díez-Sánchez, C; Ara, I; Wright-Paradis, C; Schrauwen, P; Hesselink, M; Calbet, J A L; Christiansen, M; Helge, J W; Saltin, B

    2015-12-01

    During evolution, mitochondrial DNA haplogroups of arctic populations may have been selected for lower coupling of mitochondrial respiration to ATP production in favor of higher heat production. We show that mitochondrial coupling in skeletal muscle of traditional and westernized Inuit habituating northern Greenland is identical to Danes of western Europe haplogroups. Biochemical coupling efficiency was preserved across variations in diet, muscle fiber type, and uncoupling protein-3 content. Mitochondrial phenotype displayed plasticity in relation to lifestyle and environment. Untrained Inuit and Danes had identical capacities to oxidize fat substrate in arm muscle, which increased in Danes during the 42 days of acclimation to exercise, approaching the higher level of the Inuit hunters. A common pattern emerges of mitochondrial acclimatization and evolutionary adaptation in humans at high latitude and high altitude where economy of locomotion may be optimized by preservation of biochemical coupling efficiency at modest mitochondrial density, when submaximum performance is uncoupled from VO2max and maximum capacities of oxidative phosphorylation. PMID:26589126

  9. Strategy use fully mediates the relationship between working memory capacity and performance on Raven's matrices.

    PubMed

    Gonthier, Corentin; Thomassin, Noémylle

    2015-10-01

    Working memory capacity consistently correlates with fluid intelligence. It has been suggested that this relationship is partly attributable to strategy use: Participants with high working memory capacity would use more effective strategies, in turn leading to higher performance on fluid intelligence tasks. However, this idea has never been directly investigated. In 2 experiments, we tested this hypothesis by directly manipulating strategy use in a combined experimental-correlational approach (Experiment 1; N = 250) and by measuring strategy use with a self-report questionnaire (Experiment 2; N = 93). Inducing all participants to use an effective strategy in Raven's matrices decreased the correlation between working memory capacity and performance; the strategy use measure fully mediated the relationship between working memory capacity and performance on the matrices task. These findings indicate that individual differences in strategic behavior drive the predictive utility of working memory. We interpret the results within a theoretical framework integrating the multiple mediators of the relationship between working memory capacity and high-level cognition. PMID:26413890

  10. Expertise for upright faces improves the precision but not the capacity of visual working memory

    PubMed Central

    Lorenc, Elizabeth S.; Pratte, Michael S.; Angeloni, Christopher F.; Tong, Frank

    2014-01-01

    Considerable research has focused on how basic visual features are maintained in working memory, but little is currently known about the precision or capacity of visual working memory for complex objects. How precisely can an object be remembered, and to what extent might familiarity or perceptual expertise contribute to working memory performance? To address these questions, we developed a set of computer-generated face stimuli that varied continuously along the dimensions of age and gender, and we probed participants’ memories using a method-of-adjustment reporting procedure. This paradigm allowed us to separately estimate the precision and capacity of working memory for individual faces, based on the assumptions of a discrete capacity model, and to assess the impact of face inversion on memory performance. We found that observers could maintain up to 4–5 items on average, with equally good memory capacity for upright and upside-down faces. In contrast, memory precision was significantly impaired by face inversion at every set size tested. Our results demonstrate that the precision of visual working memory for a complex stimulus is not strictly fixed, but instead can be modified by learning and experience. We find that perceptual expertise for upright faces leads to significant improvements in visual precision, without modifying the capacity of working memory. PMID:24627213

  11. Postmortem aging can significantly enhance water-holding capacity of broiler pectoralis major muscle measured by the salt-induced swelling/centrifuge method

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Water-holding capacity (WHC) is one of the most important functional properties of fresh meat and can be significantly affected by postmortem muscle changes. Two experiments were carried out to evaluate the effects of postmortem aging on WHC of broiler pectoralis (p.) major muscle indicated with % s...

  12. Effect of Treatment Table Height on Shoulder Muscles during Ultrasound Therapy Work

    PubMed Central

    Kim, Chung Yoo; Kim, In Bae; Kang, Jong Ho; Kim, Eun Kyung

    2014-01-01

    [Purpose] The purpose of this study was to propose a table height that can reduce shoulder muscle fatigue by analyzing and comparing median frequencies of shoulder muscles at different table heights when performing therapeutic ultrasounds work. [Subjects and Methods] The subjects were 63 healthy male adults who were equally and randomly assigned to a standard height group (SHG), a high height group (HHG), and a low height group (LHG). The standard table height was set at the level of the elbow joint when the subjects flexed their elbow while in a sitting position. High height and low height were set 10 cm higher and 10 cm lower, respectively, than the standard height. Muscle fatigue of the upper trapezius, middle deltoid, rhomboid, and infraspinatus of the subjects was measured during ultrasound treatment work at each table height. [Results] Median frequencies of the upper trapezius, middle deltoid, rhomboid, and infraspinatus muscles were significantly lower in the HHG than in to the LHG. [Conclusion] When therapeutic ultrasound is performed using a table that has a height lower than that of the elbow joint, the median frequency of the shoulder muscle increases, hence decreasing muscle fatigue. This way, musculoskeletal pain as a result of performing therapeutic ultrasound can be prevented. PMID:25364127

  13. Effects of Age on Maximal Work Capacity in Women Aged 18-48 Years.

    ERIC Educational Resources Information Center

    Hartung, G. Harley; And Others

    Fifty-six healthy nontrained women aged 18 to 48 were tested for maximal work capacity on a bicycle ergometer. The women were divided into three age groups. A continuous step-increment bicycle ergometer work test was administered with the workload starting at 150 kpm (kilometers per minute) and 50 pedal rpm (revolutions per minute). The workload…

  14. Visual Working Memory Capacity for Objects from Different Categories: A Face-Specific Maintenance Effect

    ERIC Educational Resources Information Center

    Wong, Jason H.; Peterson, Matthew S.; Thompson, James C.

    2008-01-01

    The capacity of visual working memory was examined when complex objects from different categories were remembered. Previous studies have not examined how visual similarity affects object memory, though it has long been known that similar-sounding phonological information interferes with rehearsal in auditory working memory. Here, experiments…

  15. The Phenotypic and Genotypic Relation between Working Memory Speed and Capacity

    ERIC Educational Resources Information Center

    Polderman, Tinca J. C.; Stins, John F.; Posthuma, Danielle; Gosso, M. Florencia; Verhulst, Frank C.; Boomsma, Dorret I.

    2006-01-01

    This study examined the phenotypic and genotypic relationship between working memory speed (WMS) and working memory capacity (WMC) in 12-year-old twins and their siblings (N = 409). To asses WMS all children performed a reaction time task with three memory loads from which a basic mental speed measure and the derived slope were used. WMC was…

  16. Hidden Knowledge: Working-Class Capacity in the "Knowledge-Based Economy"

    ERIC Educational Resources Information Center

    Livingstone, David W.; Sawchuck, Peter H.

    2005-01-01

    The research reported in this paper attempts to document the actual learning practices of working-class people in the context of the much heralded "knowledge-based economy." Our primary thesis is that working-class peoples' indigenous learning capacities have been denied, suppressed, degraded or diverted within most capitalist schooling, adult…

  17. New Rule Use Drives the Relation between Working Memory Capacity and Raven's Advanced Progressive Matrices

    ERIC Educational Resources Information Center

    Wiley, Jennifer; Jarosz, Andrew F.; Cushen, Patrick J.; Colflesh, Gregory J. H.

    2011-01-01

    The correlation between individual differences in working memory capacity and performance on the Raven's Advanced Progressive Matrices (RAPM) is well documented yet poorly understood. The present work proposes a new explanation: that the need to use a new combination of rules on RAPM problems drives the relation between performance and working…

  18. Differences in Attainment and Performance in a Foreign Language: The Role of Working Memory Capacity

    ERIC Educational Resources Information Center

    Gilabert, Roger; Munoz, Carmen

    2010-01-01

    The goal of this study is to investigate the role of working memory capacity in L2 attainment and performance. The study uses an L1 reading span task to measure working memory of a group of 59 high-intermediate/advanced learners of English, and a film retelling task to measure their oral production. The analysis first showed a moderate to high…

  19. [Role of A.A Ukhtomskiĭ in the development of the problems of work, working capacity and fatigue (peculiarities and characteristics of these states in various age periods)].

    PubMed

    Arshavskiĭ, I A

    1975-06-01

    The data of research which has been carried out for years, are summarized. They are presented in a succession conforming to the A.A. Ukhtomsky views on the gradual enlargement of amplitude of muscles contraction, on capacity for work, and on fatigue. In the early postnatal period the phenomenon of gradual enlargement of amplitude of muscles contraction does not yet exist. It only appears after realizaiton of standing posture, when skeletal muscles transit from the type of tonic activity to the phasic--tetanic type. This phenomenon is due to that the first contractions induce hyperrelaxation which leads to the subsequent higher amplitude of contraction. The steady state of work capacity of neuromuscular system without any changes of amplitude, in the conditions of undisturbed circulation in the organism as a whole, can be maintained in all the periods of age for a long time without any signs of fatigue. This phenomenon takes place during the intervals between the contraction activity, the anabolic process having ample time to be completed. Such a form of work capacity is called stability. If the anabolic processes are unable to be completed during the intervals between the contractions, their amplitude gradually decreases reflecting the beginning of fatigue. The contractile activity which is going on during the fatigue state, is called endurance. PMID:1093901

  20. Feature-Based Change Detection Reveals Inconsistent Individual Differences in Visual Working Memory Capacity.

    PubMed

    Ambrose, Joseph P; Wijeakumar, Sobanawartiny; Buss, Aaron T; Spencer, John P

    2016-01-01

    Visual working memory (VWM) is a key cognitive system that enables people to hold visual information in mind after a stimulus has been removed and compare past and present to detect changes that have occurred. VWM is severely capacity limited to around 3-4 items, although there are robust individual differences in this limit. Importantly, these individual differences are evident in neural measures of VWM capacity. Here, we capitalized on recent work showing that capacity is lower for more complex stimulus dimension. In particular, we asked whether individual differences in capacity remain consistent if capacity is shifted by a more demanding task, and, further, whether the correspondence between behavioral and neural measures holds across a shift in VWM capacity. Participants completed a change detection (CD) task with simple colors and complex shapes in an fMRI experiment. As expected, capacity was significantly lower for the shape dimension. Moreover, there were robust individual differences in behavioral estimates of VWM capacity across dimensions. Similarly, participants with a stronger BOLD response for color also showed a strong neural response for shape within the lateral occipital cortex, intraparietal sulcus (IPS), and superior IPS. Although there were robust individual differences in the behavioral and neural measures, we found little evidence of systematic brain-behavior correlations across feature dimensions. This suggests that behavioral and neural measures of capacity provide different views onto the processes that underlie VWM and CD. Recent theoretical approaches that attempt to bridge between behavioral and neural measures are well positioned to address these findings in future work. PMID:27147986

  1. Feature-Based Change Detection Reveals Inconsistent Individual Differences in Visual Working Memory Capacity

    PubMed Central

    Ambrose, Joseph P.; Wijeakumar, Sobanawartiny; Buss, Aaron T.; Spencer, John P.

    2016-01-01

    Visual working memory (VWM) is a key cognitive system that enables people to hold visual information in mind after a stimulus has been removed and compare past and present to detect changes that have occurred. VWM is severely capacity limited to around 3–4 items, although there are robust individual differences in this limit. Importantly, these individual differences are evident in neural measures of VWM capacity. Here, we capitalized on recent work showing that capacity is lower for more complex stimulus dimension. In particular, we asked whether individual differences in capacity remain consistent if capacity is shifted by a more demanding task, and, further, whether the correspondence between behavioral and neural measures holds across a shift in VWM capacity. Participants completed a change detection (CD) task with simple colors and complex shapes in an fMRI experiment. As expected, capacity was significantly lower for the shape dimension. Moreover, there were robust individual differences in behavioral estimates of VWM capacity across dimensions. Similarly, participants with a stronger BOLD response for color also showed a strong neural response for shape within the lateral occipital cortex, intraparietal sulcus (IPS), and superior IPS. Although there were robust individual differences in the behavioral and neural measures, we found little evidence of systematic brain-behavior correlations across feature dimensions. This suggests that behavioral and neural measures of capacity provide different views onto the processes that underlie VWM and CD. Recent theoretical approaches that attempt to bridge between behavioral and neural measures are well positioned to address these findings in future work. PMID:27147986

  2. Effect of Exercise-Induced Enhancement of the Leg-Extensor Muscle-Tendon Unit Capacities on Ambulatory Mechanics and Knee Osteoarthritis Markers in the Elderly

    PubMed Central

    Karamanidis, Kiros; Oberländer, Kai Daniel; Niehoff, Anja; Epro, Gaspar; Brüggemann, Gert-Peter

    2014-01-01

    Objective Leg-extensor muscle weakness could be a key component in knee joint degeneration in the elderly because it may result in altered muscular control during locomotion influencing the mechanical environment within the joint. This work aimed to examine whether an exercise-induced enhancement of the triceps surae (TS) and quadriceps femoris (QF) muscle-tendon unit (MTU) capacities would affect mechanical and biological markers for knee osteoarthritis in the elderly. Methods Twelve older women completed a 14-week TS and QF MTU exercise intervention, which had already been established as increasing muscle strength and tendon stiffness. Locomotion mechanics and serum cartilage oligomeric matrix protein (COMP) levels were examined during incline walking. MTU mechanical properties were assessed using simultaneously ultrasonography and dynamometry. Results Post exercise intervention, the elderly had higher TS and QF contractile strength and tendon-aponeurosis stiffness. Regarding the incline gait task, the subjects demonstrated a lower external knee adduction moment and lower knee adduction angular impulse during the stance phase post-intervention. Furthermore, post-intervention compared to pre-intervention, the elderly showed lower external hip adduction moment, but revealed higher plantarflexion pushoff moment. The changes in the external knee adduction moment were significantly correlated with the improvement in ankle pushoff function. Serum COMP concentration increased in response to the 0.5-h incline walking exercise with no differences in the magnitude of increment between pre- and post-intervention. Conclusions This work emphasizes the important role played by the ankle pushoff function in knee joint mechanical loading during locomotion, and may justify the inclusion of the TS MTU in prevention programs aiming to positively influence specific mechanical markers for knee osteoarthritis in the elderly. However, the study was unable to show that COMP is amenable

  3. Development of Spatial and Verbal Working Memory Capacity in the Human Brain

    ERIC Educational Resources Information Center

    Thomason, Moriah E.; Race, Elizabeth; Burrows, Brittany; Whitfield-Gabrieli, Susan; Glover, Gary H.; Gabrieli, John D. E.

    2009-01-01

    A core aspect of working memory (WM) is the capacity to maintain goal-relevant information in mind, but little is known about how this capacity develops in the human brain. We compared brain activation, via fMRI, between children (ages 7-12 years) and adults (ages 20-29 years) performing tests of verbal and spatial WM with varying amounts (loads)…

  4. Enhanced Glucose Transport, but not Phosphorylation Capacity, Ameliorates Lipopolysaccharide-Induced Impairments in Insulin-Stimulated Muscle Glucose Uptake.

    PubMed

    Otero, Yolanda F; Mulligan, Kimberly X; Barnes, Tammy M; Ford, Eric A; Malabanan, Carlo M; Zong, Haihong; Pessin, Jeffrey E; Wasserman, David H; McGuinness, Owen P

    2016-06-01

    Lipopolysaccharide (LPS) is known to impair insulin-stimulated muscle glucose uptake (MGU). We determined if increased glucose transport (GLUT4) or phosphorylation capacity (hexokinase II; HKII) could overcome the impairment in MGU. We used mice that overexpressed GLUT4 (GLUT4) or HKII (HK) in skeletal muscle. Studies were performed in conscious, chronically catheterized (carotid artery and jugular vein) mice. Mice received an intravenous bolus of either LPS (10 μg/g body weight) or vehicle (VEH). After 5 h, a hyperinsulinemic-euglycemic clamp was performed. As MGU is also dependent on cardiovascular function that is negatively affected by LPS, cardiac function was assessed using echocardiography. LPS decreased whole body glucose disposal and MGU in wild-type (WT) and HK mice. In contrast, the decrease was attenuated in GLUT4 mice. Although membrane-associated GLUT4 was increased in VEH-treated GLUT4 mice, LPS impaired membrane-associated GLUT4 in GLUT4 mice to the same level as LPS-treated WT mice. This suggested that overexpression of GLUT4 had further benefits beyond preserving transport activity. In fact, GLUT4 overexpression attenuated the LPS-induced decrease in cardiac function. The maintenance of MGU in GLUT4 mice following LPS was accompanied by sustained anaerobic glycolytic flux as suggested by increased muscle Pdk4 expression, and elevated lactate availability. Thus, enhanced glucose transport, but not phosphorylation capacity, ameliorates LPS-induced impairments in MGU. This benefit is mediated by long-term adaptations to the overexpression of GLUT4 that sustain muscle anaerobic glycolytic flux and cardiac function in response to LPS. PMID:26682946

  5. Effects of Eight Months of Whole-Body Vibration Training on the Muscle Mass and Functional Capacity of Elderly Women.

    PubMed

    Santin-Medeiros, Fernanda; Rey-López, Juan P; Santos-Lozano, Alejandro; Cristi-Montero, Carlos S; Garatachea Vallejo, Nuria

    2015-07-01

    Few intervention studies have used whole-body vibration (WBV) training in the elderly, and there is inconclusive evidence about its health benefits. We examined the effect of 8 months of WBV training on muscle mass and functional capacity in elderly women. A total of 37 women (aged 82.4 ± 5.7 years) voluntarily participated in this study. Subjects were randomly assigned to a vibration group (n = 19) or a control group (n = 18). The vibration group trained on a vertical vibration platform twice a week. The control group was requested not to change their habitual lifestyle. The quadriceps femoris muscle cross-sectional area was determined by magnetic resonance imaging. All participants were evaluated by a battery of tests (Senior Fitness Test) to determine their functional capacity, as well as handgrip strength and balance/gait. General linear repeated-measure analysis of variance (group by time) was performed to examine the effect of the intervention on the outcomes variables. After 8 months, nonstatistically significant differences in the quadriceps CSA (pre-training: 8,516.16 ± 1,271.78 mm² and post-training: 8,671.63 ± 1,389.03 mm²) (p > 0.05) were found in the WBV group (Cohen's d: -0.12), whereas the CON group significantly decreased muscle mass (pre-training: 9,756.18 ± 1,420.07 mm² and post-training: 9,326.82 ± 1,577.53 mm²), with moderate effect size evident (Cohen's d: 0.29). In both groups, no changes were observed in the functional capacity, handgrip strength and balance/gait. The WBV training could prevent the loss of quadriceps CSA in elderly women. PMID:26102257

  6. Effects of inspiratory muscle training on exercise capacity and spontaneous physical activity in elderly subjects: a randomized controlled pilot trial.

    PubMed

    Aznar-Lain, S; Webster, A L; Cañete, S; San Juan, A F; López Mojares, L M; Pérez, M; Lucia, A; Chicharro, J L

    2007-12-01

    Inspiratory muscle training (IMT) has been shown to improve exercise capacity in diseased populations. We chose to examine the effects of eight weeks of IMT on exercise capacity and spontaneous physical activity in elderly individuals. Eighteen moderately active elderly subjects (68.1 +/- 6.8 years [mean +/- SD]; range 58 - 78 years) were randomly assigned to either an experimental group (n = 9) or a control group (n = 9) in a double-blind manner. All subjects underwent inspiratory muscle testing, treadmill exercise testing and a four-day measurement period of spontaneous physical activity (using accelerometry) both pre- and post-intervention. The experimental group underwent eight weeks of incremental IMT using a pressure threshold device, while the control group underwent sham training using identical devices. After IMT training, inspiratory muscle strength (mean + 21.5 cm H (2)O; 95 % CI: 9.3, 33.7; p = 0.002), V.O (2peak) (+ 2.8 ml x min (-1) x kg (-1); 95 % CI: 0.5, 5.2; p = 0.022), time to exhaustion during a fixed workload treadmill test (+ 7.1 min; 95 % CI: 1.8, 2.4; p = 0.013) and time engaged in moderate-to-vigorous physical activity (+ 59 min; 95 % CI: 15, 78; p = 0.008) improved. Except for a decline in moderate-to-vigorous physical activity, no significant changes were seen in the control group. Therefore, IMT may be a useful technique for positively influencing exercise capacity and physical activity in elderly individuals. PMID:17534784

  7. Suppression of intrusive thoughts and working memory capacity in repressive coping.

    PubMed

    Geraerts, Elke; Merckelbach, Harald; Jelicic, Marko; Habets, Petra

    2007-01-01

    Previous research using a thought suppression paradigm found that repressors are more skilled in suppressing anxious autobiographical thoughts than low anxious, high anxious, and defensive high anxious people. Another line of research showed that individual differences in working memory capacity are related to the ability to intentionally suppress intrusive thoughts. This study aimed at combining these findings and sought to investigate whether repressors' superior ability to suppress intrusive thoughts is related to a larger working memory capacity. Results indicate that in a thought suppression paradigm, repressors report fewer intrusive thoughts for their most anxious experiences than participants in the 3 other subgroups. Furthermore, the superior ability of repressors to avoid intrusive thoughts can be explained largely by their higher working memory capacity. PMID:17650918

  8. Novel, high-intensity exercise prescription improves muscle mass, mitochondrial function, and physical capacity in individuals with Parkinson's disease

    PubMed Central

    Kelly, Neil A.; Ford, Matthew P.; Standaert, David G.; Watts, Ray L.; Bickel, C. Scott; Moellering, Douglas R.; Tuggle, S. Craig; Williams, Jeri Y.; Lieb, Laura; Windham, Samuel T.

    2014-01-01

    We conducted, in persons with Parkinson's disease (PD), a thorough assessment of neuromotor function and performance in conjunction with phenotypic analyses of skeletal muscle tissue, and further tested the adaptability of PD muscle to high-intensity exercise training. Fifteen participants with PD (Hoehn and Yahr stage 2–3) completed 16 wk of high-intensity exercise training designed to simultaneously challenge strength, power, endurance, balance, and mobility function. Skeletal muscle adaptations (P < 0.05) to exercise training in PD included myofiber hypertrophy (type I: +14%, type II: +36%), shift to less fatigable myofiber type profile, and increased mitochondrial complex activity in both subsarcolemmal and intermyofibrillar fractions (I: +45–56%, IV: +39–54%). These adaptations were accompanied by a host of functional and clinical improvements (P < 0.05): total body strength (+30–56%); leg power (+42%); single leg balance (+34%); sit-to-stand motor unit activation requirement (−30%); 6-min walk (+43 m), Parkinson's Disease Quality of Life Scale (PDQ-39, −7.8pts); Unified Parkinson's Disease Rating Scale (UPDRS) total (−5.7 pts) and motor (−2.7 pts); and fatigue severity (−17%). Additionally, PD subjects in the pretraining state were compared with a group of matched, non-PD controls (CON; did not exercise). A combined assessment of muscle tissue phenotype and neuromuscular function revealed a higher distribution and larger cross-sectional area of type I myofibers and greater type II myofiber size heterogeneity in PD vs. CON (P < 0.05). In conclusion, persons with moderately advanced PD adapt to high-intensity exercise training with favorable changes in skeletal muscle at the cellular and subcellular levels that are associated with improvements in motor function, physical capacity, and fatigue perception. PMID:24408997

  9. Muscular activity of lower limb muscles associated with working on inclined surfaces

    PubMed Central

    Lu, Ming-Lun; Kincl, Laurel; Lowe, Brian; Succop, Paul; Bhattacharya, Amit

    2015-01-01

    This study investigated effects of visual cues, muscular fatigue, task performance and experience of working on inclined surfaces on activity of postural muscles in the lower limbs associated with maintaining balance on three inclined surfaces—0°, 14° and 26°. Normalized electromyographic (NEMG) data were collected on 44 professional roofers bilaterally from the rectus femoris, biceps femoris, tibialii anterior, and gastrocnemii medial muscle groups. The 50th and 95th percentile normalized EMG amplitudes were used as EMG variables. Results showed that inclination angle and task performance caused a significant increase in the NEMG amplitudes of all postural muscles. Visual cues were significantly associated with a decrease in the 95th percentile EMG amplitude for the right gastrocnemius medial and tibialis anterior. Fatigue was related to a significant decrease in the NEMG amplitude for the rectus femoris. Experience of working on inclined surfaces did not have a significant effect on the NEMG amplitude. PMID:25331562

  10. Label-Free LC-MS Profiling of Skeletal Muscle Reveals Heart-Type Fatty Acid Binding Protein as a Candidate Biomarker of Aerobic Capacity.

    PubMed

    Malik, Zulezwan Ab; Cobley, James N; Morton, James P; Close, Graeme L; Edwards, Ben J; Koch, Lauren G; Britton, Steven L; Burniston, Jatin G

    2013-12-01

    Two-dimensional gel electrophoresis provides robust comparative analysis of skeletal muscle, but this technique is laborious and limited by its inability to resolve all proteins. In contrast, orthogonal separation by SDS-PAGE and reverse-phase liquid chromatography (RPLC) coupled to mass spectrometry (MS) affords deep mining of the muscle proteome, but differential analysis between samples is challenging due to the greater level of fractionation and the complexities of quantifying proteins based on the abundances of their tryptic peptides. Here we report simple, semi-automated and time efficient (i.e., 3 h per sample) proteome profiling of skeletal muscle by 1-dimensional RPLC electrospray ionisation tandem MS. Solei were analysed from rats (n = 5, in each group) bred as either high- or low-capacity runners (HCR and LCR, respectively) that exhibited a 6.4-fold difference (1,625 ± 112 m vs. 252 ± 43 m, p < 0.0001) in running capacity during a standardized treadmill test. Soluble muscle proteins were extracted, digested with trypsin and individual biological replicates (50 ng of tryptic peptides) subjected to LC-MS profiling. Proteins were identified by triplicate LC-MS/MS analysis of a pooled sample of each biological replicate. Differential expression profiling was performed on relative abundances (RA) of parent ions, which spanned three orders of magnitude. In total, 207 proteins were analysed, which encompassed almost all enzymes of the major metabolic pathways in skeletal muscle. The most abundant protein detected was type I myosin heavy chain (RA = 5,843 ± 897) and the least abundant protein detected was heat shock 70 kDa protein (RA = 2 ± 0.5). Sixteen proteins were significantly (p < 0.05) more abundant in HCR muscle and hierarchal clustering of the profiling data highlighted two protein subgroups, which encompassed proteins associated with either the respiratory chain or fatty acid oxidation. Heart-type fatty acid binding protein (FABPH) was 1.54-fold (p

  11. Effects of breathing exercises on lung capacity and muscle activities of elderly smokers

    PubMed Central

    Jun, Hyun-Ju; Kim, Ki-Jong; Nam, Ki-Won; Kim, Chang-Heon

    2016-01-01

    [Purpose] Elderly smokers have a reduced chest diameter due to weakening of the respiratory muscles, and this results in decreased ventilation, leading to a vicious circle. Therefore, the present study investigated the effects of an intervention program to enhance the pulmonary function and muscle activity of elderly smokers. [Subjects and Methods] Participants were randomly assigned to one of two experimental groups or a control (CG) group. The experimental groups performed exercises three times per week for six weeks, whereas the CG performed no exercises. One of the experimental groups performed a Feedback Breathing Exercise (FBE) for 15 minutes, and the other repeated three sets of Balloon-Blowing Exercises (BBE) with sufficient rest of more than one minute between sets. [Results] In the experimental groups, FVC, FEV1/FVC, PEF and muscle activity of the rectus abdominis significantly improved after four weeks, but no significant differences were observed in FEV1 or VC after six weeks. [Conclusion] The results show that FBE and BBE improved the pulmonary functions of elderly smokers, demonstrating the potential benefits of the development of various training methods using balloons, and group programs, including recreational factors, for increasing respiratory muscles strength. PMID:27390394

  12. Autonomous Extracellular Matrix Remodeling Controls a Progressive Adaptation in Muscle Stem Cell Regenerative Capacity during Development.

    PubMed

    Tierney, Matthew Timothy; Gromova, Anastasia; Sesillo, Francesca Boscolo; Sala, David; Spenlé, Caroline; Orend, Gertraud; Sacco, Alessandra

    2016-03-01

    Muscle stem cells (MuSCs) exhibit distinct behavior during successive phases of developmental myogenesis. However, how their transition to adulthood is regulated is poorly understood. Here, we show that fetal MuSCs resist progenitor specification and exhibit altered division dynamics, intrinsic features that are progressively lost postnatally. After transplantation, fetal MuSCs expand more efficiently and contribute to muscle repair. Conversely, niche colonization efficiency increases in adulthood, indicating a balance between muscle growth and stem cell pool repopulation. Gene expression profiling identified several extracellular matrix (ECM) molecules preferentially expressed in fetal MuSCs, including tenascin-C, fibronectin, and collagen VI. Loss-of-function experiments confirmed their essential and stage-specific role in regulating MuSC function. Finally, fetal-derived paracrine factors were able to enhance adult MuSC regenerative potential. Together, these findings demonstrate that MuSCs change the way in which they remodel their microenvironment to direct stem cell behavior and support the unique demands of muscle development or repair. PMID:26904948

  13. Exercise capacity and muscle strength and risk of vascular disease and arrhythmia in 1.1 million young Swedish men: cohort study

    PubMed Central

    Rasmussen, Finn; Held, Claes; Neovius, Martin; Tynelius, Per; Sundström, Johan

    2015-01-01

    Objective To investigate the associations of exercise capacity and muscle strength in late adolescence with risk of vascular disease and arrhythmia. Design Cohort study. Setting General population in Sweden. Participants 1.1 million men who participated in mandatory military conscription between 1 August 1972 and 31 December 1995, at a median age of 18.2 years. Participants were followed until 31 December 2010. Main outcomes Associations between exercise capacity and muscle strength with risk of vascular disease and subgroups (ischaemic heart disease, heart failure, stroke, and cardiovascular death) and risk of arrhythmia and subgroups (atrial fibrillation or flutter, bradyarrhythmia, supraventricular tachycardia, and ventricular arrhythmia or sudden cardiac death). Maximum exercise capacity was estimated by the ergometer bicycle test, and muscle strength was measured as handgrip strength by a hand dynamometer. High exercise capacity or muscle strength was deemed as above the median level. Results During a median follow-up of 26.3 years, 26 088 vascular disease events and 17 312 arrhythmia events were recorded. Exercise capacity was inversely associated with risk of vascular disease and its subgroups. Muscle strength was also inversely associated with vascular disease risk, driven by associations of higher muscle strength with lower risk of heart failure and cardiovascular death. Exercise capacity had a U shaped association with risk of arrhythmia, driven by a direct association with risk of atrial fibrillation and a U shaped association with bradyarrhythmia. Higher muscle strength was associated with lower risk of arrhythmia (specifically, lower risk of bradyarrhythmia and ventricular arrhythmia). The combination of high exercise capacity and high muscle strength was associated with a hazard ratio of 0.67 (95% confidence interval 0.65 to 0.70) for vascular events and 0.92 (0.88 to 0.97) for arrhythmia compared with the combination of low exercise capacity and

  14. Effects of Working Memory Capacity and Domain Knowledge on Recall for Grocery Prices.

    PubMed

    Bermingham, Douglas; Gardner, Michael K; Woltz, Dan J

    2016-01-01

    Hambrick and Engle (2002) proposed 3 models of how domain knowledge and working memory capacity may work together to influence episodic memory: a "rich-get-richer" model, a "building blocks" model, and a "compensatory" model. Their results supported the rich-get-richer model, although later work by Hambrick and Oswald (2005) found support for a building blocks model. We investigated the effects of domain knowledge and working memory on recall of studied grocery prices. Working memory was measured with 3 simple span tasks. A contrast of realistic versus fictitious foods in the episodic memory task served as our manipulation of domain knowledge, because participants could not have domain knowledge of fictitious food prices. There was a strong effect for domain knowledge (realistic food-price pairs were easier to remember) and a moderate effect for working memory capacity (higher working memory capacity produced better recall). Furthermore, the interaction between domain knowledge and working memory produced a small but significant interaction in 1 measure of price recall. This supported the compensatory model and stands in contrast to previous research. PMID:27424417

  15. Elastic ankle exoskeletons reduce soleus muscle force but not work in human hopping.

    PubMed

    Farris, Dominic James; Robertson, Benjamin D; Sawicki, Gregory S

    2013-09-01

    Inspired by elastic energy storage and return in tendons of human leg muscle-tendon units (MTU), exoskeletons often place a spring in parallel with an MTU to assist the MTU. However, this might perturb the normally efficient MTU mechanics and actually increase active muscle mechanical work. This study tested the effects of elastic parallel assistance on MTU mechanics. Participants hopped with and without spring-loaded ankle exoskeletons that assisted plantar flexion. An inverse dynamics analysis, combined with in vivo ultrasound imaging of soleus fascicles and surface electromyography, was used to determine muscle-tendon mechanics and activations. Whole body net metabolic power was obtained from indirect calorimetry. When hopping with spring-loaded exoskeletons, soleus activation was reduced (30-70%) and so was the magnitude of soleus force (peak force reduced by 30%) and the average rate of soleus force generation (by 50%). Although forces were lower, average positive fascicle power remained unchanged, owing to increased fascicle excursion (+4-5 mm). Net metabolic power was reduced with exoskeleton assistance (19%). These findings highlighted that parallel assistance to a muscle with appreciable series elasticity may have some negative consequences, and that the metabolic cost associated with generating force may be more pronounced than the cost of doing work for these muscles. PMID:23788578

  16. The effect of home-based inspiratory muscle training on exercise capacity, exertional dyspnea and pulmonary function in COPD patients

    PubMed Central

    Bavarsad, Maryam Bakhshandeh; Shariati, Abdolali; Eidani, Esmaeil; Latifi, Mahmud

    2015-01-01

    Background: Chronic obstructive pulmonary disease (COPD) is currently the fourth cause of mortality worldwide. Patients with COPD experience periods of dyspnea, fatigue, and disability, which impact on their life. The objective of this study was to investigate the effect of short-term inspiratory muscle training on exercise capacity, exertional dyspnea, and pulmonary lung function. Materials and Methods: A randomized, controlled trial was performed. Thirty patients (27 males, 3 females) with mild to very severe COPD were randomly assigned to a training group (group T) or to a control group (group C). Patients in group T received training for 8 weeks (15 min/day for 6 days/week) with flow-volumetric inspiratory exerciser named (Respivol). Each patient was assessed before and after 8 weeks of training for the following clinical parameters: exercise capacity by 6-min walking test (6MWT), exertional dyspnea by Borg scale, and pulmonary lung function by spirometry. Patients used training together with medical treatment. The data were analyzed using paired t-test and independent t-test. Results: Results showed statistically significant increase in 6MWT at the end of the training from 445.6 ± 22.99 to 491.06 ± 17.67 meters? (P < 0.001) and statistically significant decrease in dyspnea from 3.76 ± 0.64 to 1.13 ± 0.36 (P = 0.0001) in the training group but not in the control group. The values for exercise capacity and dyspnea improved after 8 weeks in group T in comparison with group C (P = 0.001 and P = 0.0001, respectively). No changes were observed in any measure of pulmonary function in both groups. Conclusions: Short-term inspiratory muscle training has beneficial effects on exercise capacity and exertional dyspnea in COPD patients. PMID:26457101

  17. The Influence of Attention Set, Working Memory Capacity, and Expectations on Inattentional Blindness.

    PubMed

    Kreitz, Carina; Furley, Philip; Memmert, Daniel; Simons, Daniel J

    2016-04-01

    The probability of inattentional blindness, the failure to notice an unexpected object when attention is engaged on some primary task, is influenced by contextual factors like task demands, features of the unexpected object, and the observer's attention set. However, predicting who will notice an unexpected object and who will remain inattentionally blind has proven difficult, and the evidence that individual differences in cognition affect noticing remains ambiguous. We hypothesized that greater working memory capacity might modulate the effect of attention sets on noticing because working memory is associated with the ability to focus attention selectively. People with greater working memory capacity might be better able to attend selectively to target items, thereby increasing the chances of noticing unexpected objects that were similar to the attended items while decreasing the odds of noticing unexpected objects that differed from the attended items. Our study (N = 120 participants) replicated evidence that task-induced attention sets modulate noticing but found no link between noticing and working memory capacity. Our results are largely consistent with the idea that individual differences in working memory capacity do not predict noticing of unexpected objects in an inattentional blindness task. PMID:26562879

  18. Functional Brain Network Modularity Captures Inter- and Intra-Individual Variation in Working Memory Capacity

    PubMed Central

    Stevens, Alexander A.; Tappon, Sarah C.; Garg, Arun; Fair, Damien A.

    2012-01-01

    Background Cognitive abilities, such as working memory, differ among people; however, individuals also vary in their own day-to-day cognitive performance. One potential source of cognitive variability may be fluctuations in the functional organization of neural systems. The degree to which the organization of these functional networks is optimized may relate to the effective cognitive functioning of the individual. Here we specifically examine how changes in the organization of large-scale networks measured via resting state functional connectivity MRI and graph theory track changes in working memory capacity. Methodology/Principal Findings Twenty-two participants performed a test of working memory capacity and then underwent resting-state fMRI. Seventeen subjects repeated the protocol three weeks later. We applied graph theoretic techniques to measure network organization on 34 brain regions of interest (ROI). Network modularity, which measures the level of integration and segregation across sub-networks, and small-worldness, which measures global network connection efficiency, both predicted individual differences in memory capacity; however, only modularity predicted intra-individual variation across the two sessions. Partial correlations controlling for the component of working memory that was stable across sessions revealed that modularity was almost entirely associated with the variability of working memory at each session. Analyses of specific sub-networks and individual circuits were unable to consistently account for working memory capacity variability. Conclusions/Significance The results suggest that the intrinsic functional organization of an a priori defined cognitive control network measured at rest provides substantial information about actual cognitive performance. The association of network modularity to the variability in an individual's working memory capacity suggests that the organization of this network into high connectivity within modules

  19. Muscle Disorders

    MedlinePlus

    Your muscles help you move and help your body work. Different types of muscles have different jobs. There are many problems that can affect muscles. Muscle disorders can cause weakness, pain or even ...

  20. Memories of early work on muscle contraction and regulation in the 1950's and 1960's

    SciTech Connect

    Huxley, Hugh E.

    2008-04-25

    Professor Ebashi's epic work on the biochemistry of the regulation of muscle contraction began in the early 1950's, during the same period that work on the molecular basis of force production in muscle was also beginning. The latter work started in two MRC Research Units in the UK, and was continued jointly by the two workers from those Units who had, independently, gone to MIT to learn the new techniques of electron microscopy and to apply them to muscle. In a somewhat similar fashion, Professor Ebashi also spent one or two years in the USA, continuing his work on the role of calcium in muscle regulation in Lippman's laboratory, before returning to Japan to achieve the great breakthroughs in this work during the 1960's. Hanson and Huxley, after putting forward the overlapping actin and myosin filament arrays model for the striated muscle sarcomere, and subsequently the sliding filament model of muscle contraction (simultaneously with A.F Huxley and R. Niedergerke), returned to the UK to pursue detailed structural studies in separate Research Units, in a mixture of consultation, collaboration, and competition, during the later 1950's and throughout the 1960's. However, the path to enlightenment described here in some detail was somewhat more tortuous than the standard literature perhaps reveals. Nevertheless, by the time of the Cold Spring Harbor Symposium on Muscle Contraction in 1972, the two lines of enquiry on regulation itself, and on the tilting cross-bridge model of force production, had arrived at a good deal of common ground, and indeed the identification of troponin and its periodic distribution along the actin filaments had helped resolve a long-standing puzzle in the interpretation of the low angle X-ray diagram. Since then, an enormous amount of remarkable new work has been necessary to establish troponin regulation and the tilting cross-bridge mechanism in molecular detail, but the work in the 1950's and 1960's has provided a firm and accurate basis

  1. Memories of early work on muscle contraction and regulation in the 1950's and 1960's.

    PubMed

    Huxley, Hugh E

    2008-04-25

    Professor Ebashi's epic work on the biochemistry of the regulation of muscle contraction began in the early 1950's, during the same period that work on the molecular basis of force production in muscle was also beginning. The latter work started in two MRC Research Units in the UK, and was continued jointly by the two workers from those Units who had, independently, gone to MIT to learn the new techniques of electron microscopy and to apply them to muscle. In a somewhat similar fashion, Professor Ebashi also spent one or two years in the USA, continuing his work on the role of calcium in muscle regulation in Lippman's laboratory, before returning to Japan to achieve the great breakthroughs in this work during the 1960's. Hanson and Huxley, after putting forward the overlapping actin and myosin filament arrays model for the striated muscle sarcomere, and subsequently the sliding filament model of muscle contraction (simultaneously with A.F Huxley and R. Niedergerke), returned to the UK to pursue detailed structural studies in separate Research Units, in a mixture of consultation, collaboration, and competition, during the later 1950's and throughout the 1960's. However, the path to enlightenment described here in some detail was somewhat more tortuous than the standard literature perhaps reveals. Nevertheless, by the time of the Cold Spring Harbor Symposium on Muscle Contraction in 1972, the two lines of enquiry on regulation itself, and on the tilting cross-bridge model of force production, had arrived at a good deal of common ground, and indeed the identification of troponin and its periodic distribution along the actin filaments had helped resolve a long-standing puzzle in the interpretation of the low angle X-ray diagram. Since then, an enormous amount of remarkable new work has been necessary to establish troponin regulation and the tilting cross-bridge mechanism in molecular detail, but the work in the 1950's and 1960's has provided a firm and accurate basis

  2. Activating HSP72 in rodent skeletal muscle increases mitochondrial number and oxidative capacity and decreases insulin resistance.

    PubMed

    Henstridge, Darren C; Bruce, Clinton R; Drew, Brian G; Tory, Kálmán; Kolonics, Attila; Estevez, Emma; Chung, Jason; Watson, Nadine; Gardner, Timothy; Lee-Young, Robert S; Connor, Timothy; Watt, Matthew J; Carpenter, Kevin; Hargreaves, Mark; McGee, Sean L; Hevener, Andrea L; Febbraio, Mark A

    2014-06-01

    Induction of heat shock protein (HSP)72 protects against obesity-induced insulin resistance, but the underlying mechanisms are unknown. Here, we show that HSP72 plays a pivotal role in increasing skeletal muscle mitochondrial number and oxidative metabolism. Mice overexpressing HSP72 in skeletal muscle (HSP72Tg) and control wild-type (WT) mice were fed either a chow or high-fat diet (HFD). Despite a similar energy intake when HSP72Tg mice were compared with WT mice, the HFD increased body weight, intramuscular lipid accumulation (triacylglycerol and diacylglycerol but not ceramide), and severe glucose intolerance in WT mice alone. Whole-body VO2, fatty acid oxidation, and endurance running capacity were markedly increased in HSP72Tg mice. Moreover, HSP72Tg mice exhibited an increase in mitochondrial number. In addition, the HSP72 coinducer BGP-15, currently in human clinical trials for type 2 diabetes, also increased mitochondrial number and insulin sensitivity in a rat model of type 2 diabetes. Together, these data identify a novel role for activation of HSP72 in skeletal muscle. Thus, the increased oxidative metabolism associated with activation of HSP72 has potential clinical implications not only for type 2 diabetes but also for other disorders where mitochondrial function is compromised. PMID:24430435

  3. Enhancing Capacity for Social Justice Work within the Academy: Building Critical Consciousness

    ERIC Educational Resources Information Center

    Ratkovic, Snezana; Tilley, Susan; Teeuwsen, Phil

    2010-01-01

    In this article, we explore our experience of carving out space within an academic program where we were able to engage in learning and teaching that enhanced our capacity to understand foundational literature in the Socio/Cultural Field of Study and work towards our social justice goals. The doctoral course described provided the conditions…

  4. Variation in Working Memory Capacity and Temporal-Contextual Retrieval from Episodic Memory

    ERIC Educational Resources Information Center

    Spillers, Gregory J.; Unsworth, Nash

    2011-01-01

    Unsworth and Engle (2007) recently proposed a model of working memory capacity characterized by, among other things, the ability to conduct a strategic, cue-dependent search of long-term memory. Although this ability has been found to mediate individual variation in a number of higher order cognitive tasks, the component processes involved remain…

  5. Working Memory Capacity and L2 University Students' Comprehension of Linear Texts and Hypertexts

    ERIC Educational Resources Information Center

    Fontanini, Ingrid; Tomitch, Leda Maria Braga

    2009-01-01

    The aim of this study was to investigate the relationship between working memory capacity and L2 reading comprehension of both linear texts and hypertexts. Three different instruments were used to measure comprehension (recall, comprehension questions and perception of contradictions) and the Reading Span Test (Daneman & Carpenter, 1980) was used…

  6. LOW-LEVEL CARBON MONOXIDE EXPOSURE AND WORK CAPACITY AT 1600 METERS

    EPA Science Inventory

    At sea level, low-level carbon monoxide (CO) exposure impairs exercise performance. To determine if altitude residence at 1600 m augments this CO effect, two studies of graded treadmill work capacity were done. The Initial Study investigated nine, non-smoking male subjects breath...

  7. Strategy Selection for Cognitive Skill Acquisition Depends on Task Demands and Working Memory Capacity

    ERIC Educational Resources Information Center

    Hinze, Scott R.; Bunting, Michael F; Pellegrino, James W.

    2009-01-01

    The involvement of working memory capacity (WMC) in ruled-based cognitive skill acquisition is well-established, but the duration of its involvement and its role in learning strategy selection are less certain. Participants (N=610) learned four logic rules, their corresponding symbols, or logic gates, and the appropriate input-output combinations…

  8. Corrective Feedback and Working Memory Capacity in Interaction-Driven L2 Learning

    ERIC Educational Resources Information Center

    Goo, Jaemyung

    2012-01-01

    The present study explores the relative efficacy of recasts over metalinguistic feedback on the learning of the English "that"-trace filter and how working memory capacity (WMC) is related to the extent to which learners can benefit from recasts and metalinguistic feedback. Fifty-four Korean English as a foreign language (EFL) learners from six…

  9. The Influence of Domain Knowledge on the Functional Capacity of Working Memory

    ERIC Educational Resources Information Center

    Ricks, Travis Rex; Wiley, Jennifer

    2009-01-01

    Theories of expertise have proposed that superior cognitive performance is in part due to increases in the functional capacity of working memory during domain-related tasks. Consistent with this approach Fincher-Kiefer et al. (1988), found that domain knowledge increased scores on baseball-related reading span tasks. The present studies extended…

  10. Effects of Differences in Working Memory Capacity on Patterns of Word Generation

    ERIC Educational Resources Information Center

    Kawamura, Mimpei; Kobayashi, Yasutaka; Morioka, Shu

    2012-01-01

    In recent years, it has been reported that WM (working memory) is concerned with word generation, but many points regarding the relationship between the individual differences of WM capacity and the patterns of word generation remain unclear. This study is to investigate these unclear points by using three types of word fluency task with different…

  11. Signed Language Working Memory Capacity of Signed Language Interpreters and Deaf Signers

    ERIC Educational Resources Information Center

    Wang, Jihong; Napier, Jemina

    2013-01-01

    This study investigated the effects of hearing status and age of signed language acquisition on signed language working memory capacity. Professional Auslan (Australian sign language)/English interpreters (hearing native signers and hearing nonnative signers) and deaf Auslan signers (deaf native signers and deaf nonnative signers) completed an…

  12. The Mediating Role of Mind Wandering in the Relationship between Working Memory Capacity and Reading Comprehension

    ERIC Educational Resources Information Center

    McVay, Jennifer C.

    2010-01-01

    The primary goal of this study was to investigate the mediating role of mind wandering in the relationship between working memory capacity (WMC) and reading comprehension as predicted by the executive-attention theory of WMC (e.g., Kane & Engle, 2003). I used a latent-variable, structural-equation-model approach with three WMC span tasks, seven…

  13. Articulatory Suppression in Language Interpretation: Working Memory Capacity, Dual Tasking and Word Knowledge

    ERIC Educational Resources Information Center

    Padilla, Francisca; Bajo, Maria Teresa; Macizo, Pedro

    2005-01-01

    How do interpreters manage to cope with the adverse effects of concurrent articulation while trying to comprehend the message in the source language? In Experiments 1-3, we explored three possible working memory (WM) functions that may underlie the ability to simultaneously comprehend and produce in the interpreters: WM storage capacity,…

  14. When Feedback Is Cognitively-Demanding: The Importance of Working Memory Capacity

    ERIC Educational Resources Information Center

    Fyfe, Emily R.; DeCaro, Marci S.; Rittle-Johnson, Bethany

    2015-01-01

    Feedback is generally considered a beneficial learning tool, and providing feedback is a recommended instructional practice. However, there are a variety of feedback types with little guidance on how to choose the most effective one. We examined individual differences in working memory capacity as a potential moderator of feedback type. Second-…

  15. Assessment of Working Memory Capacity in Preschool Children Using the Missing Scan Task

    ERIC Educational Resources Information Center

    Roman, Adrienne S.; Pisoni, David B.; Kronenberger, William G.

    2014-01-01

    The purpose of this study was to investigate the feasibility and validity of a modified version of Buschke's missing scan methodology, the Missing Scan Task (MST), to assess working memory capacity (WMC) and cognitive control processes in preschool children 3-6?years in age. Forty typically developing monolingual English-speaking children…

  16. Working Memory Capacity and Stroop Interference: Global versus Local Indices of Executive Control

    ERIC Educational Resources Information Center

    Meier, Matt E.; Kane, Michael J.

    2013-01-01

    Two experiments examined the relations among working memory capacity (WMC), congruency-sequence effects, proportion-congruency effects, and the color-word Stroop effect to test whether congruency-sequence effects might inform theoretical claims regarding WMC's prediction of Stroop interference. In Experiment 1, subjects completed either a…

  17. Why Does Working Memory Capacity Predict RAPM Performance? A Possible Role of Distraction

    ERIC Educational Resources Information Center

    Jarosz, Andrew F.; Wiley, Jennifer

    2012-01-01

    Current theories concerning individual differences in working memory capacity (WMC) suggest that WMC reflects the ability to control the focus of attention and resist interference and distraction. The current set of experiments tested whether susceptibility to distraction is partially responsible for the established relationship between…

  18. Low Working Memory Capacity Impedes both Efficiency and Learning of Number Transcoding in Children

    ERIC Educational Resources Information Center

    Camos, Valerie

    2008-01-01

    This study aimed to evaluate the impact of individual differences in working memory capacity on number transcoding. A recently proposed model, ADAPT (a developmental asemantic procedural transcoding model), accounts for the development of number transcoding from verbal form to Arabic form by two mechanisms: the learning of new production rules…

  19. Individual Differences in Working Memory Capacity and Attention, and Their Relationship with Students' Approaches to Learning

    ERIC Educational Resources Information Center

    Kyndt, Eva; Cascallar, Eduardo; Dochy, Filip

    2012-01-01

    Past research has shown that working memory capacity, attention and students' approaches to learning are all important predictors for educational achievement. In this study the interrelations between these three variables are investigated. Participants were 128 university students. Results show a negative relationship between attention and deep…

  20. Working Memory Capacity and Fluid Abilities: Examining the Correlation between Operation Span and Raven

    ERIC Educational Resources Information Center

    Unsworth, N.; Engle, R.W.

    2005-01-01

    The correlation between a measure of working memory capacity (WMC) (Operation Span) and a measure of fluid abilities (Raven Advanced Progressive Matrices) was examined. Specifically, performance on Raven problems was decomposed by difficulty, memory load, and rule type. The results suggest that the relation between Operation Span and Raven is…

  1. Individual Differences in Working Memory Capacity and Dual-Process Theories of the Mind

    ERIC Educational Resources Information Center

    Barrett, Lisa Feldman; Tugade, Michele M.; Engle, Randall W.

    2004-01-01

    Dual-process theories of the mind are ubiquitous in psychology. A central principle of these theories is that behavior is determined by the interplay of automatic and controlled processing. In this article, the authors examine individual differences in the capacity to control attention as a major contributor to differences in working memory…

  2. The Effects of Reading Purpose and Working Memory Capacity on the Processing of Expository Text.

    ERIC Educational Resources Information Center

    Linderholm, Tracy; van den Broek, Paul

    2002-01-01

    Examines the extent to which low- and high-WMC (working memory capacity) readers adjust cognitive processes to fit the reading purpose. When reading to study, low-WMC readers emphasized less demanding processes over more demanding processes to a greater extent than high-WMC readers and recalled less. When reading for entertainment, patterns of…

  3. Goal Neglect and Working Memory Capacity in 4- to 6-Year-Old Children

    ERIC Educational Resources Information Center

    Marcovitch, Stuart; Boseovski, Janet J.; Knapp, Robin J.; Kane, Michael J.

    2010-01-01

    Goal neglect is the phenomenon of failing to execute the momentary demands of a task despite understanding and being able to recall the task instructions. Successful goal maintenance is more likely to occur in adults with high working memory capacity (WMC) who can keep rules mentally accessible while performing the task. The current study…

  4. Does Domain Experience Compensate for Working Memory Capacity in Second Language Reading Comprehension?

    ERIC Educational Resources Information Center

    Payne, Tabitha W.; Kalibatseva, Zornitsa; Jungers, Melissa K.

    2009-01-01

    Reading comprehension in a second language (L2) is a complex task involving knowledge of vocabulary and grammar as well as controlled attention for continuous updating of information. The purpose was to examine the relative contributions of working memory capacity (WMC), first language (L1) comprehension, and domain experience on L2 reading…

  5. Enhancing direct access and authority for work capacity certificates to physiotherapists.

    PubMed

    Johnston, Venerina; Beales, Darren

    2016-09-01

    The mantra 'work is good for health' is familiar to those assisting in the rehabilitation of injured workers and is well supported in the literature. Regulators, workers compensation insurers and health professional bodies have taken steps over the last few years to promote early and safe return to work after a workplace injury. Improving direct access to physiotherapy and extending the role of physiotherapists to authorise work capacity certificates for injured workers will potentially facilitate early intervention, reduce absence from work in a cost-effective system while maintaining patient satisfaction. Several challenges to advancing the role of physiotherapists exist but are not insurmountable. PMID:27157489

  6. Eicosapentaenoic acid but not docosahexaenoic acid restores skeletal muscle mitochondrial oxidative capacity in old mice

    PubMed Central

    Johnson, Matthew L; Lalia, Antigoni Z; Dasari, Surendra; Pallauf, Maximilian; Fitch, Mark; Hellerstein, Marc K; Lanza, Ian R

    2015-01-01

    Mitochondrial dysfunction is often observed in aging skeletal muscle and is implicated in age-related declines in physical function. Early evidence suggests that dietary omega-3 polyunsaturated fatty acids (n-3 PUFAs) improve mitochondrial function. Here, we show that 10 weeks of dietary eicosapentaenoic acid (EPA) supplementation partially attenuated the age-related decline in mitochondrial function in mice, but this effect was not observed with docosahexaenoic acid (DHA). The improvement in mitochondrial function with EPA occurred in the absence of any changes in mitochondrial abundance or biogenesis, which was evaluated from RNA sequencing, large-scale proteomics, and direct measurements of muscle mitochondrial protein synthesis rates. We find that EPA improves muscle protein quality, specifically by decreasing mitochondrial protein carbamylation, a post-translational modification that is driven by inflammation. These results demonstrate that EPA attenuated the age-related loss of mitochondrial function and improved mitochondrial protein quality through a mechanism that is likely linked with anti-inflammatory properties of n-3 PUFAs. Furthermore, we demonstrate that EPA and DHA exert some common biological effects (anticoagulation, anti-inflammatory, reduced FXR/RXR activation), but also exhibit many distinct biological effects, a finding that underscores the importance of evaluating the therapeutic potential of individual n-3 PUFAs. PMID:26010060

  7. The impact of modality and working memory capacity on achievement in a multimedia environment

    NASA Astrophysics Data System (ADS)

    Stromfors, Charlotte M.

    This study explored the impact of working memory capacity and student learning in a dual modality, multimedia environment titled Visualizing Topography. This computer-based instructional program focused on the basic skills in reading and interpreting topographic maps. Two versions of the program presented the same instructional content but varied the modality of verbal information: the audio-visual condition coordinated topographic maps and narration; the visual-visual condition provided the same topographic maps with readable text. An analysis of covariance procedure was conducted to evaluate the effects due to the two conditions in relation to working memory capacity, controlling for individual differences in spatial visualization and prior knowledge. The scores on the Figural Intersection Test were used to separate subjects into three levels in terms of their measured working memory capacity: low, medium, and high. Subjects accessed Visualizing Topography by way of the Internet and proceeded independently through the program. The program architecture was linear in format. Subjects had a minimum amount of flexibility within each of five segments, but not between segments. One hundred and fifty-one subjects were randomly assigned to either the audio-visual or the visual-visual condition. The average time spent in the program was thirty-one minutes. The results of the ANCOVA revealed a small to moderate modality effect favoring an audio-visual condition. The results also showed that subjects with low and medium working capacity benefited more from the audio-visual condition than the visual-visual condition, while subjects with a high working memory capacity did not benefit from either condition. Although splitting the data reduced group sizes, ANCOVA results by gender suggested that the audio-visual condition favored females with low working memory capacities. The results have implications for designers of educational software, the teachers who select software, and

  8. Logistical and ergonomic transportation capacity for refuse collection workers: a work physiology field study.

    PubMed

    Luttmann, A; Laurig, W; Jäger, M

    1992-09-01

    In a work physiology field study, the work flow and the electrocardiogram were recorded throughout whole shifts for six male refuse (garbage) collection workers who transported and emptied 1.1 m3 refuse containers. The work rate (WR), indicated by the number of 1.1 m3 containers emptied per unit of time, and the work pulse rate (WPR) were determined in the data evaluation. The work pulse rate increases with the work rate. The functional relationship can be approximated by a linear regression function (WPR = 20.9 + 35.8.WR). The work pulse rate reaches such high values that it must be assumed that the work cannot be performed continuously throughout the whole working day. Consequently, regular breaks should be provided. When determining the necessary duration of the breaks, it was assumed that an equilibrium between fatigue and recovery should be maintained during the working day. The recovery breaks should be at least long enough for the heart rate to return to the resting level. The necessary duration of the breaks was determined on the basis of the present field study and the laboratory investigations described in the literature. A minimum duration of 10 min per working hour results from the calculations. The breaks should be taken regularly at about hourly intervals. A transportation-capacity model is provided for the planning of the deployment of refuse workers. It permits calculation of the number of 1.1 m3 containers a three-man crew, comprising the refuse collection truck driver and two loaders, can empty during one shift. Both the logistical and ergonomic transportation capacities can be determined using the model. The logistical transportation capacity (TCL) indicates the number of containers which can be emptied per shift by a crew when only criteria such as the optimal utilization of the working time are considered. The ergonomic transportation capacity (TCE) is understood as the number of containers which can be emptied per shift taking into

  9. An examination of the seductive details effect in terms of working memory capacity.

    PubMed

    Sanchez, Christopher A; Wiley, Jennifer

    2006-03-01

    Previous work on learning from text has demonstrated that although illustrated text can enhance comprehension, illustrations can also sometimes lead to poor learning outcomes when they are not relevant to understanding the text This phenomenon is known as the seductive details effect. The first experiment was designed to test whether the ability to control one's attention, as measured by working memory span tasks, would influence the processing of a scientific text that contained seductive (irrelevant) images, conceptually relevant images, or no illustrations. Understanding was evaluated using both an essay response and an inference verification task. Results indicated that low working memory capacity readers are especially vulnerable to the seductive details effect. In the second experiment, this issue was explored further, using eye-tracking methodology to evaluate the reading patterns of individuals who differed in working memory capacity as they read the same seductively illustrated scientific text Results indicated that low working memory individuals attend to seductive illustrations more often than not and, also, for a longer duration than do those individuals high in working memory capacity. PMID:16752598

  10. Impaired Contingent Attentional Capture Predicts Reduced Working Memory Capacity in Schizophrenia

    PubMed Central

    Mayer, Jutta S.; Fukuda, Keisuke; Vogel, Edward K.; Park, Sohee

    2012-01-01

    Although impairments in working memory (WM) are well documented in schizophrenia, the specific factors that cause these deficits are poorly understood. In this study, we hypothesized that a heightened susceptibility to attentional capture at an early stage of visual processing would result in working memory encoding problems. 30 patients with schizophrenia and 28 demographically matched healthy participants were presented with a search array and asked to report the orientation of the target stimulus. In some of the trials, a flanker stimulus preceded the search array that either matched the color of the target (relevant-flanker capture) or appeared in a different color (irrelevant-flanker capture). Working memory capacity was determined in each individual using the visual change detection paradigm. Patients needed considerably more time to find the target in the no-flanker condition. After adjusting the individual exposure time, both groups showed equivalent capture costs in the irrelevant-flanker condition. However, in the relevant-flanker condition, capture costs were increased in patients compared to controls when the stimulus onset asynchrony between the flanker and the search array was high. Moreover, the increase in relevant capture costs correlated negatively with working memory capacity. This study demonstrates preserved stimulus-driven attentional capture but impaired contingent attentional capture associated with low working memory capacity in schizophrenia. These findings suggest a selective impairment of top-down attentional control in schizophrenia, which may impair working memory encoding. PMID:23152783

  11. Toward the Neural Mechanisms of Reduced Working Memory Capacity in Schizophrenia

    PubMed Central

    Leonard, Carly J.; Kaiser, Sam T.; Robinson, Benjamin M.; Kappenman, Emily S.; Hahn, Britta; Gold, James M.; Luck, Steven J.

    2013-01-01

    People with schizophrenia (PSZ) demonstrate reliable reductions in working memory (WM) capacity (i.e., the number of objects that can be held in memory). The present study asked whether WM impairments in PSZ can be explained by the same neural mechanisms that underlie individual differences in WM capacity among healthy individuals. Specifically, we examined event-related potentials in PSZ and healthy matched controls during a change detection task that required the storage of multiple objects in WM. The amplitude of contralateral delay activity (CDA), which correlates with WM capacity in healthy individuals, was larger in controls than in PSZ for memory loads of 3 and 5 objects, but larger in PSZ than in controls for a memory load of 1. This same pattern was found in the subgroups of PSZ and controls with an equivalent WM capacity. Moreover, the increase in CDA amplitude was correlated with individual differences in capacity in controls, but not in PSZ. These results demonstrate that WM impairment in PSZ is not associated with the same patterns of neural activity that characterize low WM capacity in healthy individuals. We propose that WM impairment in PSZ instead reflects a specific impairment in the ability to distribute attention broadly. PMID:22661407

  12. Re-evaluating the relationships among filtering activity, unnecessary storage, and visual working memory capacity.

    PubMed

    Emrich, Stephen M; Busseri, Michael A

    2015-09-01

    The amount of task-irrelevant information encoded in visual working memory (VWM), referred to as unnecessary storage, has been proposed as a potential mechanism underlying individual differences in VWM capacity. In addition, a number of studies have provided evidence for additional activity that initiates the filtering process originating in the frontal cortex and basal ganglia, and is therefore a crucial step in the link between unnecessary storage and VWM capacity. Here, we re-examine data from two prominent studies that identified unnecessary storage activity as a predictor of VWM capacity by directly testing the implied path model linking filtering-related activity, unnecessary storage, and VWM capacity. Across both studies, we found that unnecessary storage was not a significant predictor of individual differences in VWM capacity once activity associated with filtering was accounted for; instead, activity associated with filtering better explained variation in VWM capacity. These findings suggest that unnecessary storage is not a limiting factor in VWM performance, whereas neural activity associated with filtering may play a more central role in determining VWM performance that goes beyond preventing unnecessary storage. PMID:25690338

  13. Differences between the Vastus Lateralis and Gastrocnemius Lateralis in the Assessment Ability of Breakpoints of Muscle Oxygenation for Aerobic Capacity Indices During an Incremental Cycling Exercise

    PubMed Central

    Wang, Bangde; Xu, Guodong; Tian, Qingping; Sun, Jinyan; Sun, Bailei; Zhang, Lei; Luo, Qingming; Gong, Hui

    2012-01-01

    In recent years, breakpoints (Bp) of muscle oxygenation have been measured in local muscles using near infrared spectroscopy (NIRS) to assess (predict) systemic aerobic capacity indices [lactate threshold (LT), gas exchange threshold (GET) and maximal oxygen uptake (VO2peak)]. We investigated muscular differences in the assessment (predictive) ability of the Bp of muscle oxygenation for aerobic capacity indices during incremental cycling exercise on the aerobic capacity indices. Thirty-one active college students were recruited for an incremental cycling exercise test, during which NIRS muscle oxygenation in the vastus lateralis (VL) and gastrocnemius lateralis (GL), blood lactate concentration and cardiopulmonary variables were measured simultaneously in a multi-modality approach. A linear regression model was used to analyse the relationship between the Bp of the muscle oxygenation index (OI) and the systemic aerobic capacity indices. The Bp of the muscle OI in both the VL (BpVL) and GL (BpGL) were significantly correlated with the aerobic capacity indices. Additionally, the BpVL had a better goodness-of-fit [higher coefficient of determination (R2, p < 0.001) and lower root mean squared error (RMSE, p < 0.03)] in the linear regressions and occurred earlier than the BpGL. In conclusion, both the BpVL and the BpGL could be measured by NIRS to assess the systemic aerobic capacity indices; however, there were muscular differences in the assessment ability of the Bp of muscle oxygenation. Key points The breakpoints (Bp) of muscle oxygenation index in both vastus lateralis (VL) and gastrocnemius lateralis (GL) could be detected to indicate the breaking up of the oxygen supply-consumption balance by NIRS. The Bp of muscle oxygenation index in both VL (BpVL) and GL (BpGL) were significantly correlated with the systemic aerobic capacity indices. The BpVL owned higher assessment (predictive) ability when the Bp (BpVL and BpGL) of muscle oxygenation index was used to

  14. Role of O2 in regulating tissue respiration in dog muscle working in situ

    NASA Technical Reports Server (NTRS)

    Hogan, M. C.; Arthur, P. G.; Bebout, D. E.; Hochachka, P. W.; Wagner, P. D.

    1992-01-01

    This study was designed to investigate the role of tissue oxygenation in some of the factors that are thought to regulate muscle respiration and metabolism. Tissue oxygenation was altered by reductions in O2 delivery (muscle blood flow x arterial O2 content), induced by decreases in arterial PO2 (PaO2). O2 uptake (VO2) was measured in isolated in situ canine gastrocnemius at rest and while working at two stimulation intensities (isometric tetanic contractions at 0.5 and 1 contractions/s) on three separate occasions, with only the level of PaO2 (78, 30, and 21 Torr) being different for each occasion. Muscle blood flow was held constant (pump perfusion) at each work intensity for the three different levels of PaO2. Muscle biopsies were obtained at the end of each rest and work period. Muscle VO2 was significantly less (P less than 0.05) at both stimulation intensities for the hypoxemic conditions, whereas [ATP] was reduced only during the highest work intensity during both hypoxemic conditions (31% reduction at 21 Torr PaO2 and 17% at 30 Torr). For each level of PaO2, the relationships between the changes that occurred in VO2 and levels of phosphocreatine, ADP, and ATP/ADP.P(i) as the stimulation intensity was increased were significantly correlated; however, the slopes and intercepts of these lines were significantly different for each PaO2. Thus a greater change in any of the proposed regulators of tissue respiration (e.g., phosphocreatine, ADP) was required to achieve a given VO2 as PaO2 was decreased.(ABSTRACT TRUNCATED AT 250 WORDS).

  15. Visuospatial Working Memory Capacity Predicts Physiological Arousal in a Narrative Task.

    PubMed

    Smithson, Lisa; Nicoladis, Elena

    2016-06-01

    Physiological arousal that occurs during narrative production is thought to reflect emotional processing and cognitive effort (Bar-Haim et al. in Dev Psychobiol 44:238-249, 2004). The purpose of this study was to determine whether individual differences in visuospatial working memory and/or verbal working memory capacity predict physiological arousal in a narrative task. Visuospatial working memory was a significant predictor of skin conductance level (SCL); verbal working memory was not. When visuospatial working memory interference was imposed, visuospatial working memory was no longer a significant predictor of SCL. Visuospatial interference also resulted in a significant reduction in SCL. Furthermore, listener ratings of narrative quality were contingent upon the visuospatial working memory resources of the narrator. Potential implications for educators and clinical practitioners are discussed. PMID:26718206

  16. Individual Differences in Working Memory Capacity and Dual-Process Theories of the Mind

    PubMed Central

    Barrett, Lisa Feldman; Tugade, Michele M.; Engle, Randall W.

    2005-01-01

    Dual-process theories of the mind are ubiquitous in psychology. A central principle of these theories is that behavior is determined by the interplay of automatic and controlled processing. In this article, the authors examine individual differences in the capacity to control attention as a major contributor to differences in working memory capacity (WMC). The authors discuss the enormous implications of this individual difference for a host of dual-process theories in social, personality, cognitive, and clinical psychology. In addition, the authors propose several new areas of investigation that derive directly from applying the concept of WMC to dual-process theories of the mind. PMID:15250813

  17. Peak frequency in the theta and alpha bands correlates with human working memory capacity.

    PubMed

    Moran, Rosalyn J; Campo, Pablo; Maestu, Fernando; Reilly, Richard B; Dolan, Raymond J; Strange, Bryan A

    2010-01-01

    Theta oscillations in the local field potential of neural ensembles are considered key mediators of human working memory. Theoretical accounts arising from animal hippocampal recordings propose that the phase of theta oscillations serves to instantiate sequential neuronal firing to form discrete representations of items held online. Human evidence of phase relationships in visual working memory has enhanced this theory, implicating long theta cycles in supporting greater memory capacity. Here we use human magnetoencephalographic recordings to examine a novel, alternative principle of theta functionality. The principle we hypothesize is derived from information theory and predicts that rather than long (low frequency) theta cycles, short (high frequency) theta cycles are best suited to support high information capacity. From oscillatory activity recorded during the maintenance period of a visual working memory task we show that a network of brain regions displays an increase in peak 4-12 Hz frequency with increasing memory load. Source localization techniques reveal that this network comprises bilateral prefrontal and right parietal cortices. Further, the peak of oscillation along this theta-alpha frequency axis is significantly higher in high capacity individuals compared to low capacity individuals. Importantly while we observe the adherence of cortical neuronal oscillations to our novel principle of theta functioning, we also observe the traditional inverse effect of low frequency theta maintaining high loads, where critically this was located in medial temporal regions suggesting parallel, dissociable hippocampal-centric, and prefrontal-centric theta mechanisms. PMID:21206531

  18. Different Roles of Direct and Indirect Frontoparietal Pathways for Individual Working Memory Capacity.

    PubMed

    Ekman, Matthias; Fiebach, Christian J; Melzer, Corina; Tittgemeyer, Marc; Derrfuss, Jan

    2016-03-01

    The ability to temporarily store and manipulate information in working memory is a hallmark of human intelligence and differs considerably across individuals, but the structural brain correlates underlying these differences in working memory capacity (WMC) are only poorly understood. In two separate studies, diffusion MRI data and WMC scores were collected for 70 and 109 healthy individuals. Using a combination of probabilistic tractography and network analysis of the white matter tracts, we examined whether structural brain network properties were predictive of individual WMC. Converging evidence from both studies showed that lateral prefrontal cortex and posterior parietal cortex of high-capacity individuals are more densely connected compared with low-capacity individuals. Importantly, our network approach was further able to dissociate putative functional roles associated with two different pathways connecting frontal and parietal regions: a corticocortical pathway and a subcortical pathway. In Study 1, where participants were required to maintain and update working memory items, the connectivity of the direct and indirect pathway was predictive of WMC. In contrast, in Study 2, where participants were required to maintain working memory items without updating, only the connectivity of the direct pathway was predictive of individual WMC. Our results suggest an important dissociation in the circuitry connecting frontal and parietal regions, where direct frontoparietal connections might support storage and maintenance, whereas subcortically mediated connections support the flexible updating of working memory content. PMID:26961945

  19. The development of a short domain-general measure of working memory capacity.

    PubMed

    Oswald, Frederick L; McAbee, Samuel T; Redick, Thomas S; Hambrick, David Z

    2015-12-01

    Working memory capacity is one of the most frequently measured individual difference constructs in cognitive psychology and related fields. However, implementation of complex span and other working memory measures is generally time-consuming for administrators and examinees alike. Because researchers often must manage the tension between limited testing time and measuring numerous constructs reliably, a short and effective measure of working memory capacity would often be a major practical benefit in future research efforts. The current study developed a shortened computerized domain-general measure of working memory capacity by representatively sampling items from three existing complex working memory span tasks: operation span, reading span, and symmetry span. Using a large archival data set (Study 1, N = 4,845), we developed and applied a principled strategy for developing the reduced measure, based on testing a series of confirmatory factor analysis models. Adequate fit indices from these models lent support to this strategy. The resulting shortened measure was then administered to a second independent sample (Study 2, N = 172), demonstrating that the new measure saves roughly 15 min (30%) of testing time on average, and even up to 25 min depending on the test-taker. On the basis of these initial promising findings, several directions for future research are discussed. PMID:25479734

  20. β-Alanine supplementation enhances human skeletal muscle relaxation speed but not force production capacity.

    PubMed

    Hannah, Ricci; Stannard, Rebecca Louise; Minshull, Claire; Artioli, Guilherme Giannini; Harris, Roger Charles; Sale, Craig

    2015-03-01

    β-Alanine (BA) supplementation improves human exercise performance. One possible explanation for this is an enhancement of muscle contractile properties, occurring via elevated intramuscular carnosine resulting in improved calcium sensitivity and handling. This study investigated the effect of BA supplementation on in vivo contractile properties and voluntary neuromuscular performance. Twenty-three men completed two experimental sessions, pre- and post-28 days supplementation with 6.4 g/day of BA (n = 12) or placebo (PLA; n = 11). During each session, force was recorded during a series of knee extensor contractions: resting and potentiated twitches and octet (8 pulses, 300 Hz) contractions elicited via femoral nerve stimulation; tetanic contractions (1 s, 1-100 Hz) via superficial muscle stimulation; and maximum and explosive voluntary contractions. BA supplementation had no effect on the force-frequency relationship, or the force responses (force at 25 and 50 ms from onset, peak force) of resting or potentiated twitches, and octet contractions (P > 0.05). Resting and potentiated twitch electromechanical delay and time-to-peak tension were unaffected by BA supplementation (P > 0.05), although half-relaxation time declined by 7-12% (P < 0.05). Maximum and explosive voluntary forces were unchanged after BA supplementation. BA supplementation had no effect on evoked force responses, implying that altered calcium sensitivity and/or release are not the mechanisms by which BA supplementation influences exercise performance. The reduced half-relaxation time with BA supplementation might, however, be explained by enhanced reuptake of calcium, which has implications for the efficiency of muscle contraction following BA supplementation. PMID:25539942

  1. Pioglitazone ameliorates the lowered exercise capacity and impaired mitochondrial function of the skeletal muscle in type 2 diabetic mice.

    PubMed

    Takada, Shingo; Hirabayashi, Kagami; Kinugawa, Shintaro; Yokota, Takashi; Matsushima, Shouji; Suga, Tadashi; Kadoguchi, Tomoyasu; Fukushima, Arata; Homma, Tsuneaki; Mizushima, Wataru; Masaki, Yoshihiro; Furihata, Takaaki; Katsuyama, Ryoichi; Okita, Koichi; Tsutsui, Hiroyuki

    2014-10-01

    We have reported that exercise capacity is reduced in high fat diet (HFD)-induced diabetic mice, and that this reduction is associated with impaired mitochondrial function in skeletal muscle (SKM). However, it remains to be clarified whether the treatment of diabetes ameliorates the reduced exercise capacity. Therefore, we examined whether an insulin-sensitizing drug, pioglitazone, could improve exercise capacity in HFD mice. C57BL/6J mice were fed a normal diet (ND) or HFD, then treated with or without pioglitazone (3 mg/kg/day) to yield the following 4 groups: ND+vehicle, ND+pioglitazone, HFD+vehicle, and HFD+pioglitazone (n=10 each). After 8 weeks, body weight, plasma glucose, and insulin in the HFD+vehicle were significantly increased compared to the ND+vehicle group. Pioglitazone normalized the insulin levels in HFD-fed mice, but did not affect the body weight or plasma glucose. Exercise capacity determined by treadmill tests was significantly reduced in the HFD+vehicle, and this reduction was almost completely ameliorated in HFD+pioglitazone mice. ADP-dependent mitochondrial respiration, complex I and III activities, and citrate synthase activity were significantly decreased in the SKM of the HFD+vehicle animals, and these decreases were also attenuated by pioglitazone. NAD(P)H oxidase activity was significantly increased in the HFD+vehicle compared with the ND+vehicle, and this increase was ameliorated in HFD+pioglitazone mice. Pioglitazone improved the exercise capacity in diabetic mice, which was due to the improvement in mitochondrial function and attenuation of oxidative stress in the SKM. Our data suggest that pioglitazone may be useful as an agent for the treatment of diabetes mellitus. PMID:24964389

  2. Neurophysiological correlates of age-related changes in working memory capacity.

    PubMed

    Mattay, Venkata S; Fera, Francesco; Tessitore, Alessandro; Hariri, Ahmad R; Berman, Karen F; Das, Saumitra; Meyer-Lindenberg, Andreas; Goldberg, Terry E; Callicott, Joseph H; Weinberger, Daniel R

    2006-01-01

    Cognitive abilities such as working memory (WM) capacity decrease with age. To determine the neurophysiological correlates of age-related reduction in working memory capacity, we studied 10 young subjects (<35 years of age; mean age=29) and twelve older subjects (>55 years of age; mean age=59) with whole brain blood oxygenation-level dependent (BOLD) fMRI on a 1.5 T GE MR scanner using a SPIRAL FLASH pulse sequence (TE=24 ms, TR=56 ms, FA=60 degrees , voxel dimensions=3.75 mm(3)). Subjects performed a modified version of the "n" back working memory task at different levels of increasing working memory load (1-Back, 2-Back and 3-Back). Older subjects performed as well as the younger subjects at 1-Back (p=0.4), but performed worse than the younger subjects at 2-Back (p<0.01) and 3-Back (p=0.06). Older subjects had significantly longer reaction time (RT) than younger subjects (p<0.04) at all levels of task difficulty. Image analysis using SPM 99 revealed a similar distribution of cortical activity between younger and older subjects at all task levels. However, an analysis of variance revealed a significant group x task interaction in the prefrontal cortex bilaterally; within working memory capacity, as in 1-Back when the older subjects performed as well as the younger subjects, they showed greater prefrontal cortical (BA 9) activity bilaterally. At higher working memory loads, however, when they performed worse then the younger subjects, the older subjects showed relatively reduced activity in these prefrontal regions. These data suggest that, within capacity, compensatory mechanisms such as additional prefrontal cortical activity are called upon to maintain proficiency in task performance. As cognitive demand increases, however, they are pushed past a threshold beyond which physiological compensation cannot be made and, a decline in performance occurs. PMID:16213083

  3. Amla Enhances Mitochondrial Spare Respiratory Capacity by Increasing Mitochondrial Biogenesis and Antioxidant Systems in a Murine Skeletal Muscle Cell Line

    PubMed Central

    Yamamoto, Hirotaka; Morino, Katsutaro; Mengistu, Lemecha; Ishibashi, Taishi; Kiriyama, Kohei; Ikami, Takao; Maegawa, Hiroshi

    2016-01-01

    Amla is one of the most important plants in Indian traditional medicine and has been shown to improve various age-related disorders while decreasing oxidative stress. Mitochondrial dysfunction is a proposed cause of aging through elevated oxidative stress. In this study, we investigated the effects of Amla on mitochondrial function in C2C12 myotubes, a murine skeletal muscle cell model with abundant mitochondria. Based on cell flux analysis, treatment with an extract of Amla fruit enhanced mitochondrial spare respiratory capacity, which enables cells to overcome various stresses. To further explore the mechanisms underlying these effects on mitochondrial function, we analyzed mitochondrial biogenesis and antioxidant systems, both proposed regulators of mitochondrial spare respiratory capacity. We found that Amla treatment stimulated both systems accompanied by AMPK and Nrf2 activation. Furthermore, we found that Amla treatment exhibited cytoprotective effects and lowered reactive oxygen species (ROS) levels in cells subjected to t-BHP-induced oxidative stress. These effects were accompanied by increased oxygen consumption, suggesting that Amla protected cells against oxidative stress by using enhanced spare respiratory capacity to produce more energy. Thus we identified protective effects of Amla, involving activation of mitochondrial function, which potentially explain its various effects on age-related disorders. PMID:27340504

  4. Yacht type and crew-specific differences in anthropometric, aerobic capacity, and muscle strength parameters among international Olympic class sailors.

    PubMed

    Bojsen-Møller, Jens; Larsson, Benny; Magnusson, S Peter; Aagaard, Per

    2007-08-01

    Physical fitness and muscular strength are important performance factors for Olympic class sailors, but the physical demands vary greatly between yacht classes, and limited information is available regarding the physical demands for the different crew positions. In the present paper, strength and aerobic capacity data from elite Olympic sailors are presented and compared with previous findings. Furthermore, a system for classification of Olympic class sailors is suggested. Peak aerobic capacity (peak oxygen uptake, VO(2peak)) and maximal isometric and isokinetic muscle strength of the knee extensors and flexors were assessed, together with the hamstring/quadriceps strength ratio (H/Q ratio). Peak aerobic capacity (ml O(2) . min(-1) . kg(-2/3)) was as follows: males - static hikers (n = 5) 215, s = 7; dynamic hikers (n = 8) 252, s = 17; trapezing helmsmen (n = 6) 234, s = 15; trapezing crew (n = 10) 239, s = 16; females - dynamic hikers (n = 6) 194, s = 16; trapezing crew (n = 2) 200, s = 13. Strength data for hikers, presented as peak moments (normalized to body weight) obtained during eccentric, isometric, and concentric contraction (Nm . kg(-1)) respectively were as follows: males - quadriceps: 3.66 (s = 0.68), 3.97 (s = 0.66), 1.82 (s = 0.34); hamstrings: 1.93 (s = 0.22), 1.38 (s = 0.41), 1.05 (s = 0.21); females - quadriceps: 3.84 (s = 0.71), 3.81 (s = 0.58), 1.60 (s = 0.28); hamstrings: 1.75 (s = 0.23), 1.10 (s = 0.16), 0.84 (s = 0.13). The peak moment based H/Q ratios for slow eccentric and concentric contractions were 0.42 (s = 0.11) and 0.39 (s = 0.04) for males and 0.43 (s = 0.06) and 0.39 (s = 0.04) for females respectively. Elite Olympic class sailors demonstrated high VO(2peak) values comparable to those observed in other non-endurance sports. The strength data revealed very high quadriceps strength for hikers, which is likely a result of the high muscle forces encountered during sailing, and a low H/Q ratio. To ensure optimal knee joint stabilization

  5. The Contribution of Attentional Lapses to Individual Differences in Visual Working Memory Capacity

    PubMed Central

    Adam, Kirsten C. S.; Mance, Irida; Fukuda, Keisuke; Vogel, Edward K.

    2015-01-01

    Attentional control and working memory capacity are important cognitive abilities that substantially vary between individuals. Although much is known about how attentional control and working memory capacity relate to each other and to constructs like fluid intelligence, little is known about how trial-by-trial fluctuations in attentional engagement impact trial-by-trial working memory performance. Here, we employ a novel whole-report memory task that allowed us to distinguish between varying levels of attentional engagement in humans performing a working memory task. By characterizing low-performance trials, we can distinguish between models in which working memory performance failures are caused by either (1) complete lapses of attention or (2) variations in attentional control. We found that performance failures increase with set-size and strongly predict working memory capacity. Performance variability was best modeled by an attentional control model of attention, not a lapse model. We examined neural signatures of performance failures by measuring EEG activity while participants performed the whole-report task. The number of items correctly recalled in the memory task was predicted by frontal theta power, with decreased frontal theta power associated with poor performance on the task. In addition, we found that poor performance was not explained by failures of sensory encoding; the P1/N1 response and ocular artifact rates were equivalent for high- and low-performance trials. In all, we propose that attentional lapses alone cannot explain individual differences in working memory performance. Instead, we find that graded fluctuations in attentional control better explain the trial-by-trial differences in working memory that we observe. PMID:25811710

  6. Conditional knockout of Mn-SOD targeted to type IIB skeletal muscle fibers increases oxidative stress and is sufficient to alter aerobic exercise capacity

    PubMed Central

    Lustgarten, Michael S.; Jang, Youngmok C.; Liu, Yuhong; Muller, Florian L.; Qi, Wenbo; Steinhelper, Mark; Brooks, Susan V.; Larkin, Lisa; Shimizu, Takahiko; Shirasawa, Takuji; McManus, Linda M.; Bhattacharya, Arunabh; Richardson, Arlan

    2009-01-01

    In vitro studies of isolated skeletal muscle have shown that oxidative stress is limiting with respect to contractile function. Mitochondria are a potential source of muscle function-limiting oxidants. To test the hypothesis that skeletal muscle-specific mitochondrial oxidative stress is sufficient to limit muscle function, we bred mice expressing Cre recombinase driven by the promoter for the inhibitory subunit of troponin (TnIFast-iCre) with mice containing a floxed Sod2 (Sod2fl/fl) allele. Mn-SOD activity was reduced by 82% in glycolytic (mainly type II) muscle fiber homogenates from young TnIFastCreSod2fl/fl mice. Furthermore, Mn-SOD content was reduced by 70% only in type IIB muscle fibers. Aconitase activity was decreased by 56%, which suggests an increase in mitochondrial matrix superoxide. Mitochondrial superoxide release was elevated more than twofold by mitochondria isolated from glycolytic skeletal muscle in TnIFastCreSod2fl/fl mice. In contrast, the rate of mitochondrial H2O2 production was reduced by 33%, and only during respiration with complex II substrate. F2-isoprostanes were increased by 36% in tibialis anterior muscles isolated from TnIFastCreSod2fl/fl mice. Elevated glycolytic muscle-specific mitochondrial oxidative stress and damage in TnIFastCreSod2fl/fl mice were associated with a decreased ability of the extensor digitorum longus and gastrocnemius muscles to produce contractile force as a function of time, whereas force production by the soleus muscle was unaffected. TnIFastCreSod2fl/fl mice ran 55% less distance on a treadmill than wild-type mice. Collectively, these data suggest that elevated mitochondrial oxidative stress and damage in glycolytic muscle fibers are sufficient to reduce contractile muscle function and aerobic exercise capacity. PMID:19776389

  7. Anxiety and working memory capacity: A meta-analysis and narrative review.

    PubMed

    Moran, Tim P

    2016-08-01

    Cognitive deficits are now widely recognized to be an important component of anxiety. In particular, anxiety is thought to restrict the capacity of working memory by competing with task-relevant processes. The evidence for this claim, however, has been mixed. Although some studies have found restricted working memory in anxiety, others have not. Within studies that have found impairments, there is little agreement regarding the boundary conditions of the anxiety/WMC association. The aim of this review is to critically evaluate the evidence for anxiety-related deficits in working memory capacity. First, a meta-analysis of 177 samples (N = 22,061 individuals) demonstrated that self-reported measures of anxiety are reliably related to poorer performance on measures of working memory capacity (g = -.334, p < 10-29). This finding was consistent across complex span (e.g., OSPAN; g = -.342, k = 30, N = 3,196, p = .000001), simple span (e.g., digit span; g = -.318, k = 127, N = 17,547, p < 10-17), and dynamic span tasks (e.g., N-Back; g = -.437, k = 20, N = 1,318, p = .000003). Second, a narrative review of the literature revealed that anxiety, whether self-reported or experimentally induced, is related to poorer performance across a wide variety of tasks. Finally, the review identified a number of methodological limitations common in the literature as well as avenues for future research. (PsycINFO Database Record PMID:26963369

  8. Analysis of Skeletal Muscle Gene Expression Patterns and the Impact of Functional Capacity in Patients With Systolic Heart Failure

    PubMed Central

    FORMAN, DANIEL E.; DANIELS, KARLA M.; CAHALIN, LAWRENCE P.; ZAVIN, ALEXANDRA; ALLSUP, KELLY; CAO, PEIRANG; SANTHANAM, MAHALAKSHMI; JOSEPH, JACOB; ARENA, ROSS; LAZZARI, ANTONIO; SCHULZE, P. CHRISTIAN; LECKER, STEWART H.

    2014-01-01

    Background Declining physical function is common among systolic heart failure (HF) patients and heralds poor clinical outcomes. We hypothesized that coordinated shifts in expression of ubiquitin-mediated atrophy-promoting genes are associated with muscle atrophy and contribute to decreased physical function. Methods Systolic HF patients (left ventricular ejection fraction [LVEF] ≤40%) underwent skeletal muscle biopsies (nondominant vastus lateralis) and comprehensive physical assessments. Skeletal muscle gene expression was assessed with the use of real-time polymerase chain reaction. Aerobic function was assessed with the use of cardiopulmonary exercise and 6-minute walk tests. Strength capacity was assessed with the use of pneumatic leg press (maximum strength and power). Serologic inflammatory markers also were assessed. Results 54 male patients (66.6 ± 10.0 years) were studied: 24 systolic HF patients (mean LVEF 28.9 ± 7.8%) and 30 age-matched control subjects. Aerobic and strength parameters were diminished in HF versus control. FoxO1 and FoxO3 were increased in HF versus control (7.9 ± 6.2 vs 5.0 ± 3.5, 6.5 ± 4.3 vs 4.3 ± 2.8 relative units, respectively; P ≤.05 in both). However, atrogin-1 and MuRF-1 were similar in both groups. PGC-1α was also increased in HF (7.9 ± 5.4 vs. 5.3 ± 3.6 relative units; P < .05). Muscle levels of insulin-like growth factor (IGF) 1 as well as serum levels of tumor necrosis factor α, C-reactive protein, inter-leukin (IL) 1β, and IL-6 were similar in HF and control. Conclusion Expression of the atrophy-promoting genes FoxO1 and FoxO3 were increased in skeletal muscle in systolic HF compared with control, but other atrophy gene expression patterns (atrogin-1 and MuRF-1), as well as growth promoting patterns (IGF-1), were similar. PGC-1α, a gene critical in enhancing mitochondrial function and moderating FoxO activity, may play an important counterregulatory role to offset ubiquitin pathwayemediated functional

  9. Statistical modelling of networked human-automation performance using working memory capacity.

    PubMed

    Ahmed, Nisar; de Visser, Ewart; Shaw, Tyler; Mohamed-Ameen, Amira; Campbell, Mark; Parasuraman, Raja

    2014-01-01

    This study examines the challenging problem of modelling the interaction between individual attentional limitations and decision-making performance in networked human-automation system tasks. Analysis of real experimental data from a task involving networked supervision of multiple unmanned aerial vehicles by human participants shows that both task load and network message quality affect performance, but that these effects are modulated by individual differences in working memory (WM) capacity. These insights were used to assess three statistical approaches for modelling and making predictions with real experimental networked supervisory performance data: classical linear regression, non-parametric Gaussian processes and probabilistic Bayesian networks. It is shown that each of these approaches can help designers of networked human-automated systems cope with various uncertainties in order to accommodate future users by linking expected operating conditions and performance from real experimental data to observable cognitive traits like WM capacity. Practitioner Summary: Working memory (WM) capacity helps account for inter-individual variability in operator performance in networked unmanned aerial vehicle supervisory tasks. This is useful for reliable performance prediction near experimental conditions via linear models; robust statistical prediction beyond experimental conditions via Gaussian process models and probabilistic inference about unknown task conditions/WM capacities via Bayesian network models. PMID:24308716

  10. The Effect of Resistance Training and Different Sources of Postexercise Protein Supplementation on Muscle Mass and Physical Capacity in Sarcopenic Elderly Men.

    PubMed

    Maltais, Mathieu L; Ladouceur, Joëlle P; Dionne, Isabelle J

    2016-06-01

    Maltais, ML, Ladouceur, JP, and Dionne, IJ. The effect of resistance training and different sources of postexercise protein supplementation on muscle mass and physical capacity in sarcopenic elderly men. J Strength Cond Res 30(6): 1680-1687, 2016-The loss of muscle mass (sarcopenia) with aging is related to a progressive loss of muscle strength and physical capacity. Resistance exercise and milk-based protein supplementation have been demonstrated as significant countermeasures for sarcopenia and the loss of muscle strength. However, using high doses of proteins can act as a meal replacement in the elderly. Therefore, we sought to determine whether a standard supplementation (12 g per serving) of protein and resistance training could be an efficient strategy to promote muscle strength and physical capacity in sarcopenic men. Twenty-six participants were randomized in 3 groups in a double-blind control study. All the groups performed exercise and consumed a protein-rich supplement 12 g of protein, 7 g of essential amino acids from milk (n = 8), soy (n = 8), or rice milk (nonprotein control, n = 10). Body composition was measured using dual-energy x-ray absorptiometry. Strength was measured by 1 repetition maximum with different exercises. Different physical capacity measurements were assessed (timed up and go test, chair stand, and walking speed). The results indicated a significant increase in fat-free mass in all groups and changes in muscle strength, with no differences between groups. This study indicates that resistance training is an effective way to increase muscle mass and strength, regardless of protein supplementation. Higher doses of protein-rich foods may have to be recommended to promote muscle mass gains when executing resistance exercise in elderly sarcopenic individuals. PMID:26562709

  11. The high aerobic capacity of a small, marsupial rat-kangaroo (Bettongia penicillata) is matched by the mitochondrial and capillary morphology of its skeletal muscles.

    PubMed

    Webster, Koa N; Dawson, Terence J

    2012-09-15

    We examined the structure-function relationships that underlie the aerobic capacities of marsupial mammals that hop. Marsupials have relatively low basal metabolic rates (BMR) and historically were seen as 'low energy' mammals. However, the red kangaroo, Macropus rufus (family Macropodidae), has aerobic capacities equivalent to athletic placentals. It has an extreme aerobic scope (fAS) and its large locomotor muscles feature high mitochondrial and capillary volumes. M. rufus belongs to a modern group of kangaroos and its high fAS is not general for marsupials. However, other hopping marsupials may have elevated aerobic capacities. Bettongia penicillata, a rat-kangaroo (family Potoroidae), is a small (1 kg), active hopper whose fAS is somewhat elevated. We examined the oxygen delivery system in its muscles to ascertain links with hopping. An elevated fAS of 23 provided a relatively high maximal aerobic oxygen consumption ( ) in B. penicillata; associated with this is a skeletal muscle mass of 44% of body mass. Ten muscles were sampled to estimate the total mitochondrial and capillary volume of the locomotor muscles. Values in B. penicillata were similar to those in M. rufus and in athletic placentals. This small hopper had high muscle mitochondrial volume densities (7.1-11.9%) and both a large total capillary volume (6 ml kg(-1) body mass) and total capillary erythrocyte volume (3.2 ml kg(-1)). Apparently, a considerable aerobic capacity is required to achieve the benefits of the extended stride in fast hopping. Of note, the ratio of to total muscle mitochondrial volume in B. penicillata was 4.9 ml O(2) min(-1) ml(-1). Similar values occur in M. rufus and also placental mammals generally, not only athletic species. If such relationships occur in other marsupials, a fundamental structure-function relationship for oxygen delivery to muscles likely originated with or before the earliest mammals. PMID:22660784

  12. Muscle mechanical work requirements during normal walking: the energetic cost of raising the body's center-of-mass is significant.

    PubMed

    Neptune, R R; Zajac, F E; Kautz, S A

    2004-06-01

    Inverted pendulum models of walking predict that little muscle work is required for the exchange of body potential and kinetic energy in single-limb support. External power during walking (product of the measured ground reaction force and body center-of-mass (COM) velocity) is often analyzed to deduce net work output or mechanical energetic cost by muscles. Based on external power analyses and inverted pendulum theory, it has been suggested that a primary mechanical energetic cost may be associated with the mechanical work required to redirect the COM motion at the step-to-step transition. However, these models do not capture the multi-muscle, multi-segmental properties of walking, co-excitation of muscles to coordinate segmental energetic flow, and simultaneous production of positive and negative muscle work. In this study, a muscle-actuated forward dynamic simulation of walking was used to assess whether: (1). potential and kinetic energy of the body are exchanged with little muscle work; (2). external mechanical power can estimate the mechanical energetic cost for muscles; and (3.) the net work output and the mechanical energetic cost for muscles occurs mostly in double support. We found that the net work output by muscles cannot be estimated from external power and was the highest when the COM moved upward in early single-limb support even though kinetic and potential energy were exchanged, and muscle mechanical (and most likely metabolic) energetic cost is dominated not only by the need to redirect the COM in double support but also by the need to raise the COM in single support. PMID:15111069

  13. Contributions of working muscle to whole body lipid metabolism are altered by exercise intensity and training.

    PubMed

    Friedlander, Anne L; Jacobs, Kevin A; Fattor, Jill A; Horning, Michael A; Hagobian, Todd A; Bauer, Timothy A; Wolfel, Eugene E; Brooks, George A

    2007-01-01

    To evaluate the contribution of working muscle to whole body lipid oxidation, we examined the effects of exercise intensity and endurance training (9 wk, 5 days/wk, 1 h, 75% Vo(2 peak)) on whole body and leg free fatty acid (FFA) kinetics in eight male subjects (26 +/- 1 yr, means +/- SE). Two pretraining trials [45 and 65% Vo(2 max) (45UT, 65UT)] and two posttraining trials [65% of pretraining Vo(2 peak) (ABT), and 65% of posttraining Vo(2 peak) (RLT)] were performed using [1-(13)C]palmitate infusion and femoral arteriovenous sampling. Training increased Vo(2 peak) by 15% (45.2 +/- 1.2 to 52.0 +/- 1.8 ml.kg(-1).min(-1), P < 0.05). Muscle FFA fractional extraction was lower during exercise (EX) compared with rest regardless of workload or training status ( approximately 20 vs. 48%, P < 0.05). Two-leg net FFA balance increased from net release at rest ( approximately -36 micromol/min) to net uptake during EX for 45UT (179 +/- 75), ABT (236 +/- 63), and RLT (136 +/- 110) (P < 0.05), but not 65UT (51 +/- 127). Leg FFA tracer measured uptake was higher during EX than rest for all trials and greater during posttraining in RLT (716 +/- 173 micromol/min) compared with pretraining (45UT 450 +/- 80, 65UT 461 +/- 72, P < 0.05). Leg muscle lipid oxidation increased with training in ABT (730 +/- 163 micromol/min) vs. 65UT (187 +/- 94, P < 0.05). Leg muscle lipid oxidation represented approximately 62 and 30% of whole body lipid oxidation at lower and higher relative intensities, respectively. In summary, training can increase working muscle tracer measured FFA uptake and lipid oxidation for a given power output, but both before and after training the association between whole body and leg lipid metabolism is reduced as exercise intensity increases. PMID:16896167

  14. Are psychologists and psychiatrists assessing work capacity part of the problem or solution?

    PubMed

    Lalić, Hrvoje

    2016-03-01

    The aim of this case study was to emphasise the importance of coordination between the members of occupational medicine teams who assess work capacity in persons whose jobs may involve responsibility for other people's safety and health. We have picked out four cases - three visiting nurses and one applicant for driving and firearms licence extension - where psychiatrists/psychologists and occupational health specialist disagreed in their assessment entirely. These cases illustrate how psychologists and psychiatrists tend to support patients' wishes to either remain at their workplace or take disability retirement, whereas occupational health specialists take a different, less easy course, relying on the medical condition of the patient, specific job requirements, and broader implications for public safety. It appears that this is not a problem only in Croatia, but in a number of developed countries as well. This problem calls for additional training of all members of a work capacity assessment team. PMID:27092641

  15. Combination of exercise training and diet restriction normalizes limited exercise capacity and impaired skeletal muscle function in diet-induced diabetic mice.

    PubMed

    Suga, Tadashi; Kinugawa, Shintaro; Takada, Shingo; Kadoguchi, Tomoyasu; Fukushima, Arata; Homma, Tsuneaki; Masaki, Yoshihiro; Furihata, Takaaki; Takahashi, Masashige; Sobirin, Mochamad A; Ono, Taisuke; Hirabayashi, Kagami; Yokota, Takashi; Tanaka, Shinya; Okita, Koichi; Tsutsui, Hiroyuki

    2014-01-01

    Exercise training (EX) and diet restriction (DR) are essential for effective management of obesity and insulin resistance in diabetes mellitus. However, whether these interventions ameliorate the limited exercise capacity and impaired skeletal muscle function in diabetes patients remains unexplored. Therefore, we investigated the effects of EX and/or DR on exercise capacity and skeletal muscle function in diet-induced diabetic mice. Male C57BL/6J mice that were fed a high-fat diet (HFD) for 8 weeks were randomly assigned for an additional 4 weeks to 4 groups: control, EX, DR, and EX+DR. A lean group fed with a normal diet was also studied. Obesity and insulin resistance induced by a HFD were significantly but partially improved by EX or DR and completely reversed by EX+DR. Although exercise capacity decreased significantly with HFD compared with normal diet, it partially improved with EX and DR and completely reversed with EX+DR. In parallel, the impaired mitochondrial function and enhanced oxidative stress in the skeletal muscle caused by the HFD were normalized only by EX+DR. Although obesity and insulin resistance were completely reversed by DR with an insulin-sensitizing drug or a long-term intervention, the exercise capacity and skeletal muscle function could not be normalized. Therefore, improvement in impaired skeletal muscle function, rather than obesity and insulin resistance, may be an important therapeutic target for normalization of the limited exercise capacity in diabetes. In conclusion, a comprehensive lifestyle therapy of exercise and diet normalizes the limited exercise capacity and impaired muscle function in diabetes mellitus. PMID:24189138

  16. What is the effect of peripheral muscle fatigue, pulmonary function, and body composition on functional exercise capacity in acromegalic patients?

    PubMed Central

    Lopes, Agnaldo José; Guedes da Silva, Débora Pedroza; Ferreira, Arthur de Sá; Kasuki, Leandro; Gadelha, Mônica Roberto; Guimarães, Fernando Silva

    2015-01-01

    [Purpose] The six-minute walk test (6MWT) is increasingly being used as an important tool for analyzing functional capacity in patients with multisystem disorders. The aim of this study was to evaluate the effect of body composition, peripheral muscle function, and pulmonary function on the six-minute walk distance (6MWD) in acromegalic patients. [Subjects and Methods] Thirty-two patients with active acromegaly, with a mean age of 48.6 ± 12.1 years, underwent an evaluation of body composition using electrical bioimpedance, isometric dynamometry with surface electromyography, tests of pulmonary function, and the 6MWT. [Results] The mean ± SD values for the 6MWD, fat-free mass (FFM), and maximal expiratory pressure (MEP) were 65.5 ± 11.7% predicted, 55.1 ± 10.6 kg, and 55.2 ± 16.8% predicted, respectively. There was a significant correlation between the 6MWD and the following parameters: the angle of the linear regression line obtained using the values of the median frequency electromyography signal over time during the fatigability test for the vastus medialis muscle (MDF, r=0.65), FFM (r=0.62), MEP (r=0.60), height(2)/resistance index (r=0.52), resistance (r=−0.50), and forced expiratory volume in 1 second (r=0.50). Multivariate analysis showed that MDF, FFM, and MEP were independent predictors of the 6MWD (R2=0.52). [Conclusion] The fatigability of the peripheral muscles, FFM, and MEP are the primary determinants of the 6MWD in acromegalics. PMID:25931716

  17. What is the effect of peripheral muscle fatigue, pulmonary function, and body composition on functional exercise capacity in acromegalic patients?

    PubMed

    Lopes, Agnaldo José; Guedes da Silva, Débora Pedroza; Ferreira, Arthur de Sá; Kasuki, Leandro; Gadelha, Mônica Roberto; Guimarães, Fernando Silva

    2015-03-01

    [Purpose] The six-minute walk test (6MWT) is increasingly being used as an important tool for analyzing functional capacity in patients with multisystem disorders. The aim of this study was to evaluate the effect of body composition, peripheral muscle function, and pulmonary function on the six-minute walk distance (6MWD) in acromegalic patients. [Subjects and Methods] Thirty-two patients with active acromegaly, with a mean age of 48.6 ± 12.1 years, underwent an evaluation of body composition using electrical bioimpedance, isometric dynamometry with surface electromyography, tests of pulmonary function, and the 6MWT. [Results] The mean ± SD values for the 6MWD, fat-free mass (FFM), and maximal expiratory pressure (MEP) were 65.5 ± 11.7% predicted, 55.1 ± 10.6 kg, and 55.2 ± 16.8% predicted, respectively. There was a significant correlation between the 6MWD and the following parameters: the angle of the linear regression line obtained using the values of the median frequency electromyography signal over time during the fatigability test for the vastus medialis muscle (MDF, r=0.65), FFM (r=0.62), MEP (r=0.60), height((2))/resistance index (r=0.52), resistance (r=-0.50), and forced expiratory volume in 1 second (r=0.50). Multivariate analysis showed that MDF, FFM, and MEP were independent predictors of the 6MWD (R(2)=0.52). [Conclusion] The fatigability of the peripheral muscles, FFM, and MEP are the primary determinants of the 6MWD in acromegalics. PMID:25931716

  18. I. WORKING MEMORY CAPACITY IN CONTEXT: MODELING DYNAMIC PROCESSES OF BEHAVIOR, MEMORY, AND DEVELOPMENT.

    PubMed

    Simmering, Vanessa R

    2016-09-01

    Working memory is a vital cognitive skill that underlies a broad range of behaviors. Higher cognitive functions are reliably predicted by working memory measures from two domains: children's performance on complex span tasks, and infants' performance in looking paradigms. Despite the similar predictive power across these research areas, theories of working memory development have not connected these different task types and developmental periods. The current project takes a first step toward bridging this gap by presenting a process-oriented theory, focusing on two tasks designed to assess visual working memory capacity in infants (the change-preference task) versus children and adults (the change detection task). Previous studies have shown inconsistent results, with capacity estimates increasing from one to four items during infancy, but only two to three items during early childhood. A probable source of this discrepancy is the different task structures used with each age group, but prior theories were not sufficiently specific to explain how performance relates across tasks. The current theory focuses on cognitive dynamics, that is, how memory representations are formed, maintained, and used within specific task contexts over development. This theory was formalized in a computational model to generate three predictions: 1) capacity estimates in the change-preference task should continue to increase beyond infancy; 2) capacity estimates should be higher in the change-preference versus change detection task when tested within individuals; and 3) performance should correlate across tasks because both rely on the same underlying memory system. I also tested a fourth prediction, that development across tasks could be explained through increasing real-time stability, realized computationally as strengthening connectivity within the model. Results confirmed these predictions, supporting the cognitive dynamics account of performance and developmental changes in real

  19. Restrictions on linear heat capacities from Joule-Brayton maximum-work cycle efficiency

    NASA Astrophysics Data System (ADS)

    Angulo-Brown, F.; Gonzalez-Ayala, Julian; Arias-Hernandez, L. A.

    2014-02-01

    This paper discusses the possibility of using the Joule-Brayton cycle to determine the accessible value range for the coefficients a and b of the heat capacity at constant pressure Cp, expressed as Cp=a+bT (with T the absolute temperature) by using the Carnot theorem. This is made for several gases which operate as the working fluids. Moreover, the landmark role of the Curzon-Ahlborn efficiency for this type of cycle is established.

  20. High methane storage and working capacities in a NbO-type metal-organic framework.

    PubMed

    Song, Chengling; Liu, Huimin; Jiao, Jingjing; Bai, Dongjie; Zhou, Wei; Yildirim, Taner; He, Yabing

    2016-05-01

    To improve methane adsorption by pore structure optimization, we developed a new organic linker and used it to construct a NbO-type metal-organic framework ZJNU-53 that, after activation, exhibits exceptionally high methane storage and working capacities of 241 and 190 cm(3) (STP) cm(-3) at 298 K and 65 bar, respectively, if the packing loss is not considered, which are among the highest reported for MOF materials. PMID:27083013

  1. How does capacity building of health managers work? A realist evaluation study protocol

    PubMed Central

    Marchal, Bruno; Hoeree, Tom; Devadasan, Narayanan; Macq, Jean; Kegels, Guy; Criel, Bart

    2012-01-01

    Introduction There has been a lot of attention on the role of human resource management interventions to improve delivery of health services in low- and middle-income countries. However, studies on this subject are few due to limited research on implementation of programmes and methodological difficulties in conducting experimental studies on human resource interventions. The authors present the protocol of an evaluation of a district-level capacity-building intervention to identify the determinants of performance of health workers in managerial positions and to understand how changes (if any) are brought about. Methods and analysis The aim of this study is to understand how capacity building works. The authors will use realist evaluation to evaluate an intervention in Karnataka, India. The intervention is a capacity-building programme that seeks to improve management capacities of health managers at district and subdistrict levels through periodic classroom-based teaching and mentoring support at the workplace. The authors conducted interviews and reviewed literature on capacity building in health to draw out the programme theory of the intervention. Based on this, the authors formulated hypothetical pathways connecting the expected outcomes of the intervention (planning and supervision) to the inputs (contact classes and mentoring). The authors prepared a questionnaire to assess elements of the programme theory—organisational culture, self-efficacy and supervision. The authors shall conduct a survey among health managers as well as collect qualitative data through interviews with participants and non-participants selected purposively based on their planning and supervision performance. The authors will construct explanations in the form of context–mechanism–outcome configurations from the results. This will be iterative and the authors will use a realist evaluation framework to refine the explanatory theories that are based on the findings to explain and

  2. Low-Level Laser Therapy (LLLT) in Dystrophin-Deficient Muscle Cells: Effects on Regeneration Capacity, Inflammation Response and Oxidative Stress

    PubMed Central

    Moraes, Luis Henrique Rapucci; Mizobuti, Daniela Sayuri; Fogaça, Aline Reis; Moraes, Fernanda dos Santos Rapucci; Hermes, Tulio de Almeida; Pertille, Adriana

    2015-01-01

    The present study evaluated low-level laser therapy (LLLT) effects on some physiological pathways that may lead to muscle damage or regeneration capacity in dystrophin-deficient muscle cells of mdx mice, the experimental model of Duchenne muscular dystrophy (DMD). Primary cultures of mdx skeletal muscle cells were irradiated only one time with laser and analyzed after 24 and 48 hours. The LLLT parameter used was 830 nm wavelengths at 5 J/cm² fluence. The following groups were set up: Ctrl (untreated C57BL/10 primary muscle cells), mdx (untreated mdx primary muscle cells), mdx LA 24 (mdx primary muscle cells - LLLT irradiated and analyzed after 24 h), and mdx LA 48 (mdx primary muscle cells - LLLT irradiated and analyzed after 48 h). The mdx LA 24 and mdx LA 48 groups showed significant increase in cell proliferation, higher diameter in muscle cells and decreased MyoD levels compared to the mdx group. The mdx LA 48 group showed significant increase in Myosin Heavy Chain levels compared to the untreated mdx and mdx LA 24 groups. The mdx LA 24 and mdx LA 48 groups showed significant increase in [Ca2+]i. The mdx group showed significant increase in H2O2 production and 4-HNE levels compared to the Ctrl group and LLLT treatment reduced this increase. GSH levels and GPx, GR and SOD activities increased in the mdx group. Laser treatment reduced the GSH levels and GR and SOD activities in dystrophic muscle cells. The mdx group showed significant increase in the TNF-α and NF-κB levels, which in turn was reduced by the LLLT treatment. Together, these results suggest that the laser treatment improved regenerative capacity and decreased inflammatory response and oxidative stress in dystrophic muscle cells, indicating that LLLT could be a helpful alternative therapy to be associated with other treatment for dystrophinopathies. PMID:26083527

  3. Functional Capacity, Respiratory Muscle Strength, and Oxygen Consumption Predict Mortality in Patients with Cirrhosis

    PubMed Central

    Telles da Rosa, Luis Henrique; Garcia, Eduardo; Marroni, Cláudio Augusto

    2016-01-01

    Introduction. Liver diseases influence musculoskeletal functions and may negatively affect the exercise capacity of patients with cirrhosis. Aim. To test the relationship between the six-minute walk test (6MWT), maximal inspiratory pressure (MIP), and exercise capacity (VO2peak) measures and the survival rate of patients with cirrhosis. Methods. This prospective cohort study consisted of 86 patients diagnosed with cirrhosis with the following aetiology: hepatitis C virus (HCV), hepatitis B virus (HBV), and/or alcoholic cirrhosis (AC). All patients were followed up for three years and submitted to the 6MWT, pressure measurements with a compound gauge, and an exercise test (VO2peak). Results. The survival analysis showed that the individuals who covered a distance shorter than 410 m during the 6MWT had a survival rate of 55% compared with a rate of 97% for the individuals who walked more than 410 m (p = 0.0001). Individuals with MIPs below −70 cmH2O had a survival rate of 62% compared with a rate of 93% for those with MIPs above −70 cmH2O (p = 0.0001). The patients with values below 17 mL/kg had a survival rate of 55% compared with a rate of 94% for those with values above 17 mL/kg (p = 0.0001). Conclusion. The 6MWT distance, MIP, and oxygen consumption are predictors of mortality in patients with cirrhosis. PMID:27559536

  4. Functional Capacity, Respiratory Muscle Strength, and Oxygen Consumption Predict Mortality in Patients with Cirrhosis.

    PubMed

    Faustini Pereira, José Leonardo; Galant, Lucas Homercher; Rossi, Danusa; Telles da Rosa, Luis Henrique; Garcia, Eduardo; de Mello Brandão, Ajácio Bandeira; Marroni, Cláudio Augusto

    2016-01-01

    Introduction. Liver diseases influence musculoskeletal functions and may negatively affect the exercise capacity of patients with cirrhosis. Aim. To test the relationship between the six-minute walk test (6MWT), maximal inspiratory pressure (MIP), and exercise capacity (VO2peak) measures and the survival rate of patients with cirrhosis. Methods. This prospective cohort study consisted of 86 patients diagnosed with cirrhosis with the following aetiology: hepatitis C virus (HCV), hepatitis B virus (HBV), and/or alcoholic cirrhosis (AC). All patients were followed up for three years and submitted to the 6MWT, pressure measurements with a compound gauge, and an exercise test (VO2peak). Results. The survival analysis showed that the individuals who covered a distance shorter than 410 m during the 6MWT had a survival rate of 55% compared with a rate of 97% for the individuals who walked more than 410 m (p = 0.0001). Individuals with MIPs below -70 cmH2O had a survival rate of 62% compared with a rate of 93% for those with MIPs above -70 cmH2O (p = 0.0001). The patients with values below 17 mL/kg had a survival rate of 55% compared with a rate of 94% for those with values above 17 mL/kg (p = 0.0001). Conclusion. The 6MWT distance, MIP, and oxygen consumption are predictors of mortality in patients with cirrhosis. PMID:27559536

  5. Regulation of Skeletal Muscle Oxidative Capacity and Insulin Signaling by the Mitochondrial Rhomboid Protease PARL

    PubMed Central

    Civitarese, Anthony E.; MacLean, Paul S.; Carling, Stacy; Kerr-Bayles, Lyndal; McMillan, Ryan P.; Pierce, Anson; Becker, Thomas C.; Moro, Cedric; Finlayson, Jean; Lefort, Natalie; Newgard, Christopher B.; Mandarino, Lawrence; Cefalu, William; Walder, Ken; Collier, Greg R.; Hulver, Matthew W.; Smith, Steven R.; Ravussin, Eric

    2010-01-01

    SUMMARY Type 2 diabetes Mellitus (T2DM) and aging are characterized by insulin resistance, lower mitochondrial density and function and increased production of reactive oxygen species (ROS). In lower organisms continuous remodeling critically maintains the function and life cycle of mitochondria, in part by the protease pcp1 (PARL ortholog). We therefore examined whether variation in PARL protein content is associated with mitochondrial abnormalities and insulin resistance. Relative to healthy, young individuals (23±1y), PARL mRNA and mitochondrial mass were both reduced in elderly subjects (64.4±1.2 y; 51% and 44% respectively) and in subjects with T2DM (51.8±3 y; 31% and 41% respectively; all p<0.05). Muscle knock-down of PARL in mice resulted in lower mitochondrial content (−31±3%, p<0.05), lower OPA1 and PGC1α protein levels and impaired insulin signaling. Furthermore, mitochondrial cristae were malformed and resulted in elevated in vivo oxidative stress. Adenoviral suppression of PARL protein in healthy myotubes lowered mitochondrial mass (−33±8%), insulin stimulated glycogen synthesis (−33±9%) and increased ROS production (2-fold) (all p<0.05). We propose that lower PARL expression may contribute to the mitochondrial abnormalities seen in aging and T2DM. PMID:20444421

  6. Effect of dietary organic selenium on muscle proteolytic activity and water-holding capacity in pork.

    PubMed

    Calvo, L; Toldrá, F; Aristoy, M C; López-Bote, C J; Rey, A I

    2016-11-01

    This study evaluates the effect of dietary selenium (Se) supplementation source (organic, Se-enriched yeast; SY vs. inorganic, sodium selenite; SS), dose (0.2: L vs. 0.4: H mg/kg) and the combination of Se and vitamin E (VITE+SS) for 26days on drip loss, TBARS, colour changes, myofibrillar protein pattern and proteolysis in pork. The lowest water losses were observed in the SY-H group when compared to the others. SY-H and VITE+SS groups presented lower myofibrillar protein hydrolysis/oxidation. VITE+SS supplementation also resulted in higher PRO, TRP and PHE content at days 2 and 7, whereas the SY group showed increased GLY and CAR and tended to have higher TAU and ANS at day 2. The myofibrillar fragmentation index was not modified by the dietary treatment; however, at day 8, it tended to be higher in groups supplemented with SeY and VITE+SS. The results of the present study might indicate a possible relation between muscle proteolysis and water loss. PMID:27232379

  7. Effects of short-term ingestion of Russian Tarragon prior to creatine monohydrate supplementation on whole body and muscle creatine retention and anaerobic sprint capacity: a preliminary investigation

    PubMed Central

    2014-01-01

    Background Extracts of Russian Tarragon (RT) have been reported to produce anti-hyperglycemic effects and influence plasma creatine (Cr) levels while supplementing with creatine monohydrate (CrM). The purpose of this preliminary study was to determine if short-term, low-dose aqueous RT extract ingestion prior to CrM supplementation influences whole body Cr retention, muscle Cr or measures of anaerobic sprint performance. Methods In a double-blind, randomized, and crossover manner; 10 recreationally trained males (20 ± 2 yrs; 179 ± 9 cm; 91.3 ± 34 kg) ingested 500 mg of aqueous RT extract (Finzelberg, Andernach, Germany) or 500 mg placebo 30-minutes prior to ingesting 5 g of CrM (Creapure®, AlzChem AG, Germany) twice per day for 5-days then repeated after a 6-week wash-out period. Urine was collected at baseline and during each of the 5-days of supplementation to determine urine Cr content. Whole body Cr retention was estimated from urine samples. Muscle biopsies were obtained for determination of muscle free Cr content. Participants also performed two 30-second Wingate anaerobic capacity tests prior to and following supplementation for determination of peak power (PP), mean power (MP), and total work (TW). Data were analysed by repeated measures MANOVA. Results Whole body daily Cr retention increased in both groups following supplementation (0.0 ± 0.0; 8.2 ± 1.4, 6.5 ± 2.4, 5.6 ± 3.2, 6.1 ± 2.6, 4.8 ± 3.2 g · d-1; p = 0.001) with no differences observed between groups (p = 0.59). After 3 and 5-days of supplementation, respectively, both supplementation protocols demonstrated a significant increase in muscle free Cr content from baseline (4.8 ± 16.7, 15.5 ± 23.6 mmol · kg-1 DW, p = 0.01) with no significant differences observed between groups (p = 0.34). Absolute change in MP (9 ± 57, 35 ± 57 W; p = 0.031), percent change in MP (2.5 ± 10.5, 6.7 ± 10

  8. Conditional independence mapping of DIGE data reveals PDIA3 protein species as key nodes associated with muscle aerobic capacity

    PubMed Central

    Burniston, Jatin G.; Kenyani, Jenna; Gray, Donna; Guadagnin, Eleonora; Jarman, Ian H.; Cobley, James N.; Cuthbertson, Daniel J.; Chen, Yi-Wen; Wastling, Jonathan M.; Lisboa, Paulo J.; Koch, Lauren G.; Britton, Steven L.

    2014-01-01

    Profiling of protein species is important because gene polymorphisms, splice variations and post-translational modifications may combine and give rise to multiple protein species that have different effects on cellular function. Two-dimensional gel electrophoresis is one of the most robust methods for differential analysis of protein species, but bioinformatic interrogation is challenging because the consequences of changes in the abundance of individual protein species on cell function are unknown and cannot be predicted. We conducted DIGE of soleus muscle from male and female rats artificially selected as either high- or low-capacity runners (HCR and LCR, respectively). In total 696 protein species were resolved and LC–MS/MS identified proteins in 337 spots. Forty protein species were differentially (P < 0.05, FDR < 10%) expressed between HCR and LCR and conditional independence mapping found distinct networks within these data, which brought insight beyond that achieved by functional annotation. Protein disulphide isomerase A3 emerged as a key node segregating with differences in aerobic capacity and unsupervised bibliometric analysis highlighted further links to signal transducer and activator of transcription 3, which were confirmed by western blotting. Thus, conditional independence mapping is a useful technique for interrogating DIGE data that is capable of highlighting latent features. PMID:24769234

  9. High Methane Storage Working Capacity in Metal-Organic Frameworks with Acrylate Links.

    PubMed

    Jiang, Juncong; Furukawa, Hiroyasu; Zhang, Yue-Biao; Yaghi, Omar M

    2016-08-17

    High methane storage capacity in porous materials is important for the design and manufacture of vehicles powered by natural gas. Here, we report the synthesis, crystal structures and methane adsorption properties of five new zinc metal-organic frameworks (MOFs), MOF-905, MOF-905-Me2, MOF-905-Naph, MOF-905-NO2, and MOF-950. All these MOFs consist of the Zn4O(-CO2)6 secondary building units (SBUs) and benzene-1,3,5-tri-β-acrylate, BTAC. The permanent porosity of all five materials was confirmed, and their methane adsorption measured up to 80 bar to reveal that MOF-905 is among the best performing methane storage materials with a volumetric working capacity (desorption at 5 bar) of 203 cm(3) cm(-3) at 80 bar and 298 K, a value rivaling that of HKUST-1 (200 cm(3) cm(-3)), the benchmark compound for methane storage in MOFs. This study expands the scope of MOF materials with ultrahigh working capacity to include linkers having the common acrylate connectivity. PMID:27442620

  10. The effect of individual differences in working memory capacity on sentence comprehension: an FMRI study.

    PubMed

    Newman, Sharlene D; Malaia, Evie; Seo, Roy; Cheng, Hu

    2013-07-01

    This study explores the interaction between working memory systems and language processing by examining how differences in working memory capacity (WMC) modulates neural activation levels and functional connectivity during sentence comprehension. The results indicate that two working memory systems may be involved in sentence comprehension, the verbal working memory system and the episodic buffer, but during different phases of the task. A sub-region of the left inferior frontal gyrus (BA 45) was correlated with WMC during the probe and not during sentence reading while the only region to reveal a correlation with WMC during sentence reading was the posterior cingulate/precuneus area, a region linked to event representation. In addition, functional connectivity analysis suggests that there were two distinct networks affected by WMC. The first was a semantic network that included the middle temporal cortex, an anterior region of the inferior frontal gyrus and the inferior parietal region. The second included the posterior cingulate and BA 45 of the inferior frontal gyrus. We propose here that high capacity readers may generate an event representation of the sentence during reading that aids in comprehension and that this event representation involves the processing of the posterior cingulate cortex. PMID:23124385

  11. Focused attention improves working memory: implications for flexible-resource and discrete-capacity models.

    PubMed

    Souza, Alessandra S; Rerko, Laura; Lin, Hsuan-Yu; Oberauer, Klaus

    2014-10-01

    Performance in working memory (WM) tasks depends on the capacity for storing objects and on the allocation of attention to these objects. Here, we explored how capacity models need to be augmented to account for the benefit of focusing attention on the target of recall. Participants encoded six colored disks (Experiment 1) or a set of one to eight colored disks (Experiment 2) and were cued to recall the color of a target on a color wheel. In the no-delay condition, the recall-cue was presented after a 1,000-ms retention interval, and participants could report the retrieved color immediately. In the delay condition, the recall-cue was presented at the same time as in the no-delay condition, but the opportunity to report the color was delayed. During this delay, participants could focus attention exclusively on the target. Responses deviated less from the target's color in the delay than in the no-delay condition. Mixture modeling assigned this benefit to a reduction in guessing (Experiments 1 and 2) and transposition errors (Experiment 2). We tested several computational models implementing flexible or discrete capacity allocation, aiming to explain both the effect of set size, reflecting the limited capacity of WM, and the effect of delay, reflecting the role of attention to WM representations. Both models fit the data better when a spatially graded source of transposition error is added to its assumptions. The benefits of focusing attention could be explained by allocating to this object a higher proportion of the capacity to represent color. PMID:24874258

  12. Effect of day length on oxidative capacities of mitochondria from red muscle of rainbow trout (Oncorhynchus mykiss).

    PubMed

    Martin, Nicolas; Kraffe, Edouard; Guderley, Helga

    2009-04-01

    In nature, seasons may be more reliably announced by changes in photoperiod than in temperature. To evaluate the role of day length in setting oxidative capacities of trout muscle mitochondria, we acclimated trout to summer (15 degrees C, 16L:8D), winter (5 degrees C, 8L:16D) and mixed conditions (15 degrees C, 8L:16D). Maximal oxidative capacities of isolated mitochondria at 5 and 15 degrees C were higher in mixed than summer conditions and higher again in winter conditions. At 5 degrees C, state 4 rates changed little with acclimation state whereas at 15 degrees C state 4 rates were lower in summer than in mixed or winter conditions. Using concentrations of the adenylate nucleotide translocase as the denominator for these rates gave much the same conclusions. By using inhibitors to block flux at specific points in the electron transport chain, we found that flux through Complexes II-IV was lowest in summer acclimated trout, increased upon acclimation to mixed and to winter conditions. Flux through complex IV was similar in trout acclimated to summer and mixed conditions, but increased significantly with acclimation to winter conditions. Flux through complex IV was 1.5 fold higher than state 3 rates for summer-acclimated trout but was similar to state 3 rates in trout acclimated to mixed or winter conditions. Our results indicate that a reduction in day length initiates increases in mitochondrial oxidative capacity typically associated with cold acclimation and that acclimation to both cold temperatures and short day lengths enhanced these changes. The overall similarity of the responses of state 3, of flux through complexes II-IV and of flux through complex IV suggests that a generalised mechanism such as changes in the phospholipid composition of the inner mitochondrial membrane may coordinate these changes. PMID:19256041

  13. ZK-5: a CO₂-selective zeolite with high working capacity at ambient temperature and pressure.

    PubMed

    Liu, Qingling; Pham, Trong; Porosoff, Marc D; Lobo, Raul F

    2012-11-01

    The increased carbon dioxide concentration in the atmosphere caused by combustion of fossil fuels has been a leading contributor to global climate change. The adsorption-driven pressure or vacuum swing (PSA/VSA) processes are promising as affordable means for the capture and separation of CO₂. Herein, an 8-membered-ring zeolite ZK-5 (Framework Type Code: KFI) exchanged with different cations (H⁺, Li⁺, Na⁺, K⁺, Mg²⁺, Ca²⁺) was synthesized as novel CO₂ adsorbent. The samples were characterized by SEM, energy-dispersive X-ray spectroscopy (EDAX), XRD, and gas adsorption (CO₂ and N₂). The Toth adsorption model was used to describe the CO₂ adsorption isotherms, and the isosteric heats of adsorption were calculated. CO₂ capture adsorbent evaluation criteria such as working capacity, regenerability and CO₂/N₂ selectivity were applied to evaluate the zeolite adsorbents for PSA/VSA applications. The in situ FTIR CO₂ adsorption spectra show that physisorption accounts for the largest fraction of the total CO₂ adsorbed. The CO₂ adsorption analysis shows that Mg-ZK-5 is the most promising adsorbent for PSA applications with the highest working capacity (ΔN(CO₂)=2.05 mmol g⁻¹), excellent selectivity (α(CO₂/N₂)=121), and low isosteric heat. Li-, Na- and K-ZK-5 with good working capacity (ΔN(CO₂)=1.55-2.16 mmol g⁻¹) and excellent selectivity (α(CO₂/N₂)=103-128) are promising CO₂ adsorbents for the VSA working region. PMID:22907818

  14. Bronchitis in two integrated steel works: III. Respiratory symptoms and ventilatory capacity related to atmospheric pollution

    PubMed Central

    Lowe, C. R.; Campbell, H.; Khosla, T.

    1970-01-01

    Lowe, C. R., Campbell, H., and Khosla, T.(1970).Brit. J. industr. Med.,27, 121-129. Bronchitis in two integrated steel works. III. Respiratory symptoms and ventilatory capacity related to atmospheric pollution. This is the third in a series of papers presenting the results of an epidemiological study of respiratory symptomatology and lung function among men employed in two integrated steel works in South Wales. In this paper measurements of atmospheric pollution are related to respiratory symptoms and ventilatory capacity among 10 449 men who spent the greater part of their working hours in one or other of 114 defined working areas. The problem has been explored in three different ways. In the first, each man was assigned the mean value of sulphur dioxide and respirable dust for the area in which he was working and this was related to his ventilatory capacity (FEV1·0), age, smoking habits, and the number of years he had spent in his present department. In the second, the 114 working areas were divided into four sub-groups, according to defined levels of atmospheric pollution, and the prevalence of chronic bronchitis and mean FEV1·0 in the four sub-groups was examined. In the third way, the mean atmospheric pollution levels in each of the 114 areas were related to the prevalence of bronchitis and to the mean FEV1·0, age, and smoking habits in those areas. The analysis demonstrates very clearly the over-riding importance of cigarette smoking in the aetiology of chronic bronchitis, but, so far as the main purpose of the survey is concerned, it is concluded that, if there is any relation between respiratory disability and atmospheric pollution in the two steel works, it is so slight that none of the three approaches to the problem was sensitive enough to detect it. The implications of this are discussed in the light of the levels of pollution that were recorded in and around the two works. PMID:5428631

  15. Effects of Working Memory Capacity and Content Familiarity on Literal and Inferential Comprehension in L2 Reading

    ERIC Educational Resources Information Center

    Alptekin, Cem; Ercetin, Gulcan

    2011-01-01

    This study examines the effects of working memory capacity and content familiarity on literal and inferential comprehension in second language (L2) reading. Participants were 62 Turkish university students with an advanced English proficiency level. Working memory capacity was measured through a computerized version of a reading span test, whereas…

  16. Does Domain Knowledge Moderate Involvement of Working Memory Capacity in Higher-Level Cognition? A Test of Three Models

    ERIC Educational Resources Information Center

    Hambrick, D.Z.; Oswald, F.L.

    2005-01-01

    Research suggests that both working memory capacity and domain knowledge contribute to individual differences in higher-level cognition. This study evaluated three hypotheses concerning the interplay between these factors. The compensation hypothesis predicts that domain knowledge attenuates the influence of working memory capacity on higher-level…

  17. Building the Capacity of First Year Social Work Students: Experiences from a South African Tertiary Education Institution

    ERIC Educational Resources Information Center

    Drower, Sandra J.; Kleijn, Amelia A.

    2008-01-01

    A three part Building Capacity Program developed for social work students in a South African tertiary education institution is described. The primary purpose of the Program was to build the capacity of social work students considered to be at risk of not completing their studies. The Program is located within the socio-political context of South…

  18. Effects of Aerobic Dance on Physical Work Capacity, Cardiovascular Function and Body Composition of Middle-Age Women.

    ERIC Educational Resources Information Center

    Dowdy, Deborah B.; And Others

    1985-01-01

    This study proposed to determine the effects of aerobics on physical work capacity, cardiovascular function and body composition of 28 women aged 25 to 44 years. Measurements taken after a conditioning program showed significant changes in work capacity and cardiovascular function for the conditioned group but no change in body composition.…

  19. [The effect of bromantane on the physical work capacity of laboratory animals].

    PubMed

    Morozov, I S; Kleĭmenova, N N

    1998-01-01

    The positive effect of bromantan (0.5-50 mg/kg) on the efficiency of physical work of mice and rats (swimming test, running on a treadmill) exceeds that of phenamine administered in optimal doses by 1.3-1.6 times. Such an effect of bromantan lasts no less than 24 h. The drug delays decrease of physical efficiency and restores it sooner in repeated extreme running loads, prevents in rats the corresponding electron-microscopic changes in the cardiomyocyte and myocyte mitochondria of the skeletal muscles. The data obtained suggest that the positive effect of bromantan on the physical efficiency is associated not only with its psychostimulating action but also with the membrane-protecting effect. PMID:9929819

  20. Remembering complex objects in visual working memory: do capacity limits restrict objects or features?

    PubMed

    Hardman, Kyle O; Cowan, Nelson

    2015-03-01

    Visual working memory stores stimuli from our environment as representations that can be accessed by high-level control processes. This study addresses a longstanding debate in the literature about whether storage limits in visual working memory include a limit to the complexity of discrete items. We examined the issue with a number of change-detection experiments that used complex stimuli that possessed multiple features per stimulus item. We manipulated the number of relevant features of the stimulus objects in order to vary feature load. In all of our experiments, we found that increased feature load led to a reduction in change-detection accuracy. However, we found that feature load alone could not account for the results but that a consideration of the number of relevant objects was also required. This study supports capacity limits for both feature and object storage in visual working memory. PMID:25089739

  1. Finnish farmers' self-reported morbidity, work ability, and functional capacity.

    PubMed

    Perkio-Makela, M M

    2000-01-01

    The aim of the study was to evaluate Finnish farmers' self-reported morbidity, especially musculoskeletal disease and disabilities, work ability, physical fitness, and functional capacity. A further goal was to identify the group of farmers that most need a means to promote their work ability. The data were collected with a computer-assisted telephone interview. The study population comprised of 577 full-time farmers (296 men and 281 women). The results have been expressed as odds ratios with 95% confidence intervals determined in a logistic regression analysis. The farmers with the greatest need for activities that support and promote work ability are those over 34 years of age, female farmers, farmers with fewer than 10 years of education, farmers from farms with fewer than 20 hectares of cultivated land, farmers who milk cows regularly, and depressed farmers. PMID:10865239

  2. The interaction among age, thermal acclimation and growth rate in determining muscle metabolic capacities and tissue masses in the threespine stickleback, Gasterosteus aculeatus.

    PubMed

    Guderley, H; Lavoie, B A; Dubois, N

    1994-11-01

    Thermal acclimation may directly modify muscle metabolic capacities, or may modify them indirectly via effects upon physiological processes such as growth, reproduction or senescence. To evaluate these interacting effects, we examined the influence of thermal acclimation and acclimatization upon muscle metabolic capacities and tissue masses in 1 + stickleback, Gasterosteus aculeatus, in which confounding interactions between temperature and senescense should be absent. Furthermore, we examined the influence of thermal acclimation upon individual growth rate, muscle enzyme levels and tissue masses in 2 + stickleback sampled at the beginning of their final reproductive season. For 1 + stickleback, cold acclimation more than doubles mitochondrial enzyme levels in the axial muscle. Thermal acclimation did not change the condition of 1 + stickleback at feeding levels which could not maintain the condition of 2+ stickleback. Compensatory metabolic responses to temperature were not apparent in field acclimatized 1 + stickleback. The growth rate of 2 + stickleback was markedly affected by temperature: warm-acclimated fish generally lost mass even at very high levels of feeding (up to 78 enchytraid worms per day) while cold-acclimated fish gained mass. This suggests that warm temperatures accelerate the senescence of 2 + stickleback. Generally, muscle enzyme activities increased with growth rate. In axial muscle, the relationships between CS activity and growth rate differed with acclimation temperature. Independent of the influence of growth rate, CS activities were consistently higher in cold- than warm-acclimated 2 + stickleback, suggesting compensatory increases of CS activity with cold acclimation. PMID:24197078

  3. Skeletal Muscle-Specific Expression of PGC-1α-b, an Exercise-Responsive Isoform, Increases Exercise Capacity and Peak Oxygen Uptake

    PubMed Central

    Tadaishi, Miki; Miura, Shinji; Kai, Yuko; Kano, Yutaka; Oishi, Yuichi; Ezaki, Osamu

    2011-01-01

    Background Maximal oxygen uptake (VO2max) predicts mortality and is associated with endurance performance. Trained subjects have a high VO2max due to a high cardiac output and high metabolic capacity of skeletal muscles. Peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), a nuclear receptor coactivator, promotes mitochondrial biogenesis, a fiber-type switch to oxidative fibers, and angiogenesis in skeletal muscle. Because exercise training increases PGC-1α in skeletal muscle, PGC-1α-mediated changes may contribute to the improvement of exercise capacity and VO2max. There are three isoforms of PGC-1α mRNA. PGC-1α-b protein, whose amino terminus is different from PGC-1α-a protein, is a predominant PGC-1α isoform in response to exercise. We investigated whether alterations of skeletal muscle metabolism by overexpression of PGC-1α-b in skeletal muscle, but not heart, would increase VO2max and exercise capacity. Methodology/Principal Findings Transgenic mice showed overexpression of PGC-1α-b protein in skeletal muscle but not in heart. Overexpression of PGC-1α-b promoted mitochondrial biogenesis 4-fold, increased the expression of fatty acid transporters, enhanced angiogenesis in skeletal muscle 1.4 to 2.7-fold, and promoted exercise capacity (expressed by maximum speed) by 35% and peak oxygen uptake by 20%. Across a broad range of either the absolute exercise intensity, or the same relative exercise intensities, lipid oxidation was always higher in the transgenic mice than wild-type littermates, suggesting that lipid is the predominant fuel source for exercise in the transgenic mice. However, muscle glycogen usage during exercise was absent in the transgenic mice. Conclusions/Significance Increased mitochondrial biogenesis, capillaries, and fatty acid transporters in skeletal muscles may contribute to improved exercise capacity via an increase in fatty acid utilization. Increases in PGC-1α-b protein or function might be a useful strategy

  4. Complex myograph allows the examination of complex muscle contractions for the assessment of muscle force, shortening, velocity, and work in vivo

    PubMed Central

    Rahe-Meyer, Niels; Pawlak, Matthias; Weilbach, Christian; Osthaus, Wilhelm Alexander; Ruhschulte, Hainer; Solomon, Cristina; Piepenbrock, Siegfried; Winterhalter, Michael

    2008-01-01

    Background The devices used for in vivo examination of muscle contractions assess only pure force contractions and the so-called isokinetic contractions. In isokinetic experiments, the extremity and its muscle are artificially moved with constant velocity by the measuring device, while a tetanic contraction is induced in the muscle, either by electrical stimulation or by maximal voluntary activation. With these systems, experiments cannot be performed at pre-defined, constant muscle length, single contractions cannot be evaluated individually and the separate examination of the isometric and the isotonic components of single contractions is not possible. Methods The myograph presented in our study has two newly developed technical units, i.e. a). a counterforce unit which can load the muscle with an adjustable, but constant force and b). a length-adjusting unit which allows for both the stretching and the contraction length to be infinitely adjustable independently of one another. The two units support the examination of complex types of contraction and store the counterforce and length-adjusting settings, so that these conditions may be accurately reapplied in later sessions. Results The measurement examples presented show that the muscle can be brought to every possible pre-stretching length and that single isotonic or complex isometric-isotonic contractions may be performed at every length. The applied forces act during different phases of contraction, resulting into different pre- and after-loads that can be kept constant – uninfluenced by the contraction. Maximal values for force, shortening, velocity and work may be obtained for individual muscles. This offers the possibility to obtain information on the muscle status and to monitor its changes under non-invasive measurement conditions. Conclusion With the Complex Myograph, the whole spectrum of a muscle's mechanical characteristics may be assessed. PMID:18616815

  5. Work capacity, thermal responses and lung function: united kingdom studies in the L.B.P.

    PubMed

    Weiner, J S

    1976-07-01

    Results of physiological studies from some ten U.K. Human Adaptability projects are presented. U.K. investigators made major contributions in developing and adapting techniques for the assussment under field conditions of work capacity, heat tolerance and respiratory function. The various ethnic studies of work capacity revealed the special role of body size and muscularity, as well as training, in determining the observed inter- and intra-population variance. The results on samples from U.K., New Guinea, the Caribbean, Israel, West and East Africa and the Ethiopian highlands gave no indication that genetic difference were significant in determining population differences. Differences in heat tolerance reflect in general the intensity of heat exposure, especially when combined with hard physical work. Indigenous peoples in Africa and New Guinea show some modification in sweating responses which do not appear to be genetically determined but are in some way, as yet not clearly established, attributable to long continued residence in tropical climates. In renal function of some seven ethnic groups were analysed in terms of lung volume bellows function, gas exchange and responses to excercise and carbon dioxide. The relative importance of genetic and non-genetic factors was examined. PMID:8802

  6. Exploring age differences in visual working memory capacity: is there a contribution of memory for configuration?

    PubMed

    Cowan, Nelson; Saults, J Scott; Clark, Katherine M

    2015-07-01

    Recent research has shown marked developmental increases in the apparent capacity of working memory. This recent research is based largely on performance on tasks in which a visual array is to be retained briefly for comparison with a subsequent probe display. Here we examined a possible theoretical alternative (or supplement) to a developmental increase in working memory in which children could improve in the ability to combine items in an array to form a coherent configuration. Elementary school children and adults received, on each trial, an array of colored spots to be remembered. On some trials, we provided structure in the probe display to facilitate the formation of a mental representation in which a coherent configuration is encoded. This stimulus structure in the probe display helped younger children, and thus reduced the developmental trend, but only on trials in which the participants were held responsible for the locations of items in the array. We conclude that, in addition to the development of the ability to form precise spatial configurations from items, the evidence is consistent with the existence of an actual developmental increase in working memory capacity for objects in an array. PMID:25841172

  7. Treatment of glycogenosys type V (McArdle disease) with creatine and ketogenic diet with clinical scores and with 31P-MRS on working leg muscle

    PubMed Central

    Vorgerd, M; Zange, J

    2007-01-01

    Summary McArdle’s disease is caused by genetic defects of the musclespecific isozyme of glycogen phosphorylase, which block ATP formation from glycogen in skeletal muscle. Creatine supplementation and ketogenic diet have been tested as potential supplements for muscle energy metabolism which may improve muscle symptomatic. Outcome measures were clinical scores describing muscle symptomatic and parameters derived from 31P-MRS examinations on working muscle. In two placebo controlled cross-over studies low dose creatine showed beneficial effects on muscle symptoms and performance whereas high dose creatine distinctly worsened muscle symptomatic in patients. In both studies, however, the absence of an elevation in phosphocreatine indicated the absence of a creatine uptake by the muscle fibre. The effects of creatine on muscle symptomatic may be independent from energy metabolism in muscle. In a case study, ketogenic diet improved muscle symptomatic and performance. However, these effects again did not result in 31PMRS visible changes in muscle energy metabolism. PMID:17915573

  8. Restrictions on linear heat capacities from Joule-Brayton maximum-work cycle efficiency.

    PubMed

    Angulo-Brown, F; Gonzalez-Ayala, Julian; Arias-Hernandez, L A

    2014-02-01

    This paper discusses the possibility of using the Joule-Brayton cycle to determine the accessible value range for the coefficients a and b of the heat capacity at constant pressure C(p), expressed as C(p) = a + bT (with T the absolute temperature) by using the Carnot theorem. This is made for several gases which operate as the working fluids. Moreover, the landmark role of the Curzon-Ahlborn efficiency for this type of cycle is established. PMID:25353449

  9. Developmental improvements in the resolution and capacity of visual working memory share a common source.

    PubMed

    Simmering, Vanessa R; Miller, Hilary E

    2016-08-01

    The nature of visual working memory (VWM) representations is currently a source of debate between characterizations as slot-like versus a flexibly-divided pool of resources. Recently, a dynamic neural field model has been proposed as an alternative account that focuses more on the processes by which VWM representations are formed, maintained, and used in service of behavior. This dynamic model has explained developmental increases in VWM capacity and resolution through strengthening excitatory and inhibitory connections. Simulations of developmental improvements in VWM resolution suggest that one important change is the accuracy of comparisons between items held in memory and new inputs. Thus, the ability to detect changes is a critical component of developmental improvements in VWM performance across tasks, leading to the prediction that capacity and resolution should correlate during childhood. Comparing 5- to 8-year-old children's performance across color discrimination and change detection tasks revealed the predicted correlation between estimates of VWM capacity and resolution, supporting the hypothesis that increasing connectivity underlies improvements in VWM during childhood. These results demonstrate the importance of formalizing the processes that support the use of VWM, rather than focusing solely on the nature of representations. We conclude by considering our results in the broader context of VWM development. PMID:27329264

  10. Metallic muscles at work: high rate actuation in nanoporous gold/polyaniline composites.

    PubMed

    Detsi, Eric; Onck, Patrick; De Hosson, Jeff Th M

    2013-05-28

    Metallic muscles made of nanoporous metals suffer from serious drawbacks caused by the usage of an aqueous electrolyte for actuation. An aqueous electrolyte prohibits metallic muscles from operating in dry environments and hampers a high actuation rate due to the low ionic conductivity of electrolytes. In addition, redox reactions involved in electrochemical actuation severely coarsen the ligaments of nanoporous metals, leading to a substantial loss in performance of the actuator. Here we present an electrolyte-free approach to put metallic muscles to work via a metal/polymer interface. A nanocoating of polyaniline doped with sulfuric acid was grown onto the ligaments of nanoporous gold. Dopant sulfate anions coadsorbed into the polymer coating matrix were exploited to tune the nanoporous metal surface stress and subsequently generate macroscopic dimensional changes in the metal. Strain rates achieved in the single-component nanoporous metal/polymer composite actuator are 3 orders of magnitude higher than that of the standard three-component nanoporous metal/electrolyte hybrid actuator. PMID:23582044

  11. Muscle work is biased toward energy generation over dissipation in non-level running

    PubMed Central

    DeVita, Paul; Janshen, Lars; Rider, Patrick; Solnik, Stanislaw; Hortobágyi, Tibor

    2008-01-01

    This study tested the hypothesis that skeletal muscles generate more mechanical energy in gait tasks that raise the center of mass compared to the mechanical energy they dissipate in gait tasks that lower the center of mass despite equivalent changes in total mechanical energy. Thirteen adults ran on a 10° decline and incline surface at a constant average velocity. Three-dimensional (3D) joint powers were calculated from ground force and 3D kinematic data using inverse dynamics. Joint work was calculated from the power curves and assumed to be due to skeletal muscle–tendon actuators. External work was calculated from the kinematics of the pelvis through the gait cycle. Incline vs. decline running was characterized with smaller ground forces that operated over longer lever arms causing larger joint torques and work from these torques. Total lower extremity joint work was 28% greater in incline vs. decline running (1.32 vs. −1.03 J/kg m, p<0.001). Total lower extremity joint work comprised 86% and 71% of the total external work in incline (1.53 J/kg m) and decline running (−1.45 J/kg m), which themselves were not significantly different (p<0.180). We conjectured that the larger ground forces in decline vs. incline running caused larger accelerations of all body tissues and initiated a greater energy-dissipating response in these tissues compared to their response in incline running. The runners actively lowered themselves less during decline stance and descended farther as projectiles than they lifted themselves during incline stance and ascended as projectiles. These data indicated that despite larger ground forces in decline running, the reduced displacement during downhill stance phases limited the work done by muscle contraction in decline compared to incline running. PMID:19010471

  12. ERP markers of target selection discriminate children with high vs. low working memory capacity

    PubMed Central

    Shimi, Andria; Nobre, Anna Christina; Scerif, Gaia

    2015-01-01

    Selective attention enables enhancing a subset out of multiple competing items to maximize the capacity of our limited visual working memory (VWM) system. Multiple behavioral and electrophysiological studies have revealed the cognitive and neural mechanisms supporting adults’ selective attention of visual percepts for encoding in VWM. However, research on children is more limited. What are the neural mechanisms involved in children’s selection of incoming percepts in service of VWM? Do these differ from the ones subserving adults’ selection? Ten-year-olds and adults used a spatial arrow cue to select a colored item for later recognition from an array of four colored items. The temporal dynamics of selection were investigated through EEG signals locked to the onset of the memory array. Both children and adults elicited significantly more negative activity over posterior scalp locations contralateral to the item to-be-selected for encoding (N2pc). However, this activity was elicited later and for longer in children compared to adults. Furthermore, although children as a group did not elicit a significant N2pc during the time-window in which N2pc was elicited in adults, the magnitude of N2pc during the “adult time-window” related to their behavioral performance during the later recognition phase of the task. This in turn highlights how children’s neural activity subserving attention during encoding relates to better subsequent VWM performance. Significant differences were observed when children were divided into groups of high vs. low VWM capacity as a function of cueing benefit. Children with large cue benefits in VWM capacity elicited an adult-like contralateral negativity following attentional selection of the to-be-encoded item, whereas children with low VWM capacity did not. These results corroborate the close coupling between selective attention and VWM from childhood and elucidate further the attentional mechanisms constraining VWM performance in

  13. Probing the early development of visual working memory capacity with functional near-infrared spectroscopy.

    PubMed

    Buss, Aaron T; Fox, Nicholas; Boas, David A; Spencer, John P

    2014-01-15

    Visual working memory (VWM) is a core cognitive system with a highly limited capacity. The present study is the first to examine VWM capacity limits in early development using functional neuroimaging. We recorded optical neuroimaging data while 3- and 4-year-olds completed a change detection task where they detected changes in the shapes of objects after a brief delay. Near-infrared sources and detectors were placed over the following 10-20 positions: F3 and F5 in left frontal cortex, F4 and F6 in right frontal cortex, P3 and P5 in left parietal cortex, and P4 and P6 in right parietal cortex. The first question was whether we would see robust task-specific activation of the frontal-parietal network identified in the adult fMRI literature. This was indeed the case: three left frontal channels and 11 of 12 parietal channels showed a statistically robust difference between the concentration of oxygenated and deoxygenated hemoglobin following the presentation of the sample array. Moreover, four channels in the left hemisphere near P3, P5, and F5 showed a robust increase as the working memory load increased from 1 to 3 items. Notably, the hemodynamic response did not asymptote at 1-2 items as expected from previous fMRI studies with adults. Finally, 4-year-olds showed a more robust parietal response relative to 3-year-olds, and an increasing sensitivity to the memory load manipulation. These results demonstrate that fNIRS is an effective tool to study the neural processes that underlie the early development of VWM capacity. PMID:23707803

  14. Muscle Deoxygenation Causes Muscle Fatigue

    NASA Technical Reports Server (NTRS)

    Murthy, G.; Hargens, A. R.; Lehman, S.; Rempel, D.

    1999-01-01

    Muscle fatigue is a common musculoskeletal disorder in the work place, and may be a harbinger for more disabling cumulative trauma disorders. Although the cause of fatigue is multifactorial, reduced blood flow and muscle oxygenation may be the primary factor in causing muscle fatigue during low intensity muscle exertion. Muscle fatigue is defined as a reduction in muscle force production, and also occurs among astronauts who are subjected to postural constraints while performing lengthy, repetitive tasks. The objectives of this research are to: 1) develop an objective tool to study the role of decreased muscle oxygenation on muscle force production, and 2) to evaluate muscle fatigue during prolonged glovebox work.

  15. Individual Differences in Working Memory Capacity Modulates Semantic Negative Priming from Single Prime Words

    PubMed Central

    Ortells, Juan J.; Noguera, Carmen; Álvarez, Dolores; Carmona, Encarna; Houghton, George

    2016-01-01

    The present study investigated whether semantic negative priming from single prime words depends on the availability of cognitive control resources. Participants with high vs. low working memory capacity (as assessed by their performance in complex span and attentional control tasks) were instructed to either attend to or ignore a briefly presented single prime word that was followed by either a semantically related or unrelated target word on which participants made a lexical decision. Individual differences in working memory capacity (WMC) mainly affected the processing of the ignored primes, but not the processing of the attended primes: While the latter produced reliable positive semantic priming for both high- and low-WMC participants, the former gave rise to reliable semantic negative priming only for high WMC participants, with low WMC participants showing the opposite positive priming effect. The present results extend previous findings in demonstrating that (a) single negative priming can reliably generalize to semantic associates of the prime words, and (b) a differential availability of cognitive control resources can reliably modulate the negative priming effect at a semantic level of representation. PMID:27621716

  16. Assessment of Working Memory Capacity in Preschool Children Using the Missing Scan Task

    PubMed Central

    Roman, Adrienne S.; Pisoni, David B.; Kronenberger, William G.

    2014-01-01

    The purpose of this study was to investigate the feasibility and validity of a modified version of Buschke’s missing scan methodology, the Missing Scan Task (MST), to assess working memory capacity (WMC) and cognitive control processes in preschool children 3–6 years in age. Forty typically developing monolingual English-speaking children between 36 and 84 months in age participated in the study. The children were tested on measures of WMC (MST), verbal and nonverbal memory (NEPSY Narrative Memory and Memory for Designs subtests), and language skills (Peabody Picture Vocabulary Test, fourth edition). Children showed increased working memory capacity scores with age, as measured by the MST, with significant differences between 3- and 5-year-olds and 3- and 6-year-olds. Significant correlations were also found between the MST and language and verbal and nonverbal memory scores. MSTscores still remained significantly correlated with the other measures of memory even after age and global language were accounted for in a regression analysis, demonstrating that the MST captures unique variance related specifically to WMC and cognitive control processes used to retrieve and scan information in short-term memory (STM). The results of this study demonstrate that the MST is a feasible and valid methodology for assessing WMC in preschool children as young 3 years of age. PMID:25642148

  17. Individual Differences in Working Memory Capacity Modulates Semantic Negative Priming from Single Prime Words.

    PubMed

    Ortells, Juan J; Noguera, Carmen; Álvarez, Dolores; Carmona, Encarna; Houghton, George

    2016-01-01

    The present study investigated whether semantic negative priming from single prime words depends on the availability of cognitive control resources. Participants with high vs. low working memory capacity (as assessed by their performance in complex span and attentional control tasks) were instructed to either attend to or ignore a briefly presented single prime word that was followed by either a semantically related or unrelated target word on which participants made a lexical decision. Individual differences in working memory capacity (WMC) mainly affected the processing of the ignored primes, but not the processing of the attended primes: While the latter produced reliable positive semantic priming for both high- and low-WMC participants, the former gave rise to reliable semantic negative priming only for high WMC participants, with low WMC participants showing the opposite positive priming effect. The present results extend previous findings in demonstrating that (a) single negative priming can reliably generalize to semantic associates of the prime words, and (b) a differential availability of cognitive control resources can reliably modulate the negative priming effect at a semantic level of representation. PMID:27621716

  18. Effect of hot working on the damping capacity and mechanical properties of AZ31 magnesium alloy

    NASA Astrophysics Data System (ADS)

    Lee, K.; Kang, C.; Kim, K.

    2015-04-01

    Magnesium alloys have received much attention for their lightweight and other excellent properties, such as low density, high specific strength, and good castability, for use in several industrial and commercial applications. However, both magnesium and its alloys show limited room-temperature formability owing to the limited number of slip systems associated with their hexagonal close-packed crystal structure. It is well known that crystallographic texture plays an important role in both plastic deformation and macroscopic anisotropy of magnesium alloys. Many authors have concentrated on improving the room- temperature formability of Mg alloys. However, despite having a lot of excellent properties in magnesium alloy, the study for various properties of magnesium alloy have not been clarified enough yet. Mg alloys are known to have a good damping capacity compared to other known metals and their alloys. Also, the damping properties of metals are generally recognized to be dependent on microstructural factors such as grain size and texture. However, there are very few studies on the relationship between the damping capacity and texture of Magnesium alloys. Therefore, in this study, specimens of the AZ31 magnesium alloy, were processed by hot working, and their texture and damping property investigated. A 60 mm × 60 mm × 40 mm rectangular plate was cut out by machining an ingot of AZ31 magnesium alloy (Mg-3Al-1Zn in mass%), and rolling was carried out at 673 K to a rolling reduction of 30%. Then, heat treatment was carried out at temperatures in the range of 573-723 K for durations in the range of 30-180 min. The samples were immediately quenched in oil after heat treatment to prevent any change in the microstructure. Texture was evaluated on the compression planes by the Schulz reflection method using nickel-filtered Cu Kα radiation. Electron backscatter diffraction measurements were conducted to observe the spatial distribution of various orientations. Specimens

  19. Active biofeedback changes the spatial distribution of upper trapezius muscle activity during computer work.

    PubMed

    Samani, Afshin; Holtermann, Andreas; Søgaard, Karen; Madeleine, Pascal

    2010-09-01

    The aim of this study was to investigate the spatio-temporal effects of advanced biofeedback by inducing active and passive pauses on the trapezius activity pattern using high-density surface electromyography (HD-EMG). Thirteen healthy male subjects performed computer work with superimposed feedback either eliciting passive (rest) or active (approximately 30% MVC) pauses based on fuzzy logic design and a control session with no feedback. HD-EMG signals of upper trapezius were recorded using a 5 x 13 multichannel electrode grid. From the HD-EMG recordings, two-dimensional maps of root mean square (RMS), relative rest time (RRT) and permuted sample entropy (PeSaEn) were obtained. The centre of gravity (CoG) and entropy of maps were used to quantify changes in the spatial distribution of muscle activity. PeSaEn as a measure of temporal heterogeneity for each channel, decreased over the whole map in response to active pause (P < 0.05) underlining a more homogenous activation pattern. Concomitantly, the CoG of RRT maps moved in caudal direction and the entropy of RMS maps as a measure of spatial heterogeneity over the whole recording grid, increased in response to active pause session compared with control session (no feedback) (P < 0.05). Active pause compared with control resulted in more heterogeneous coordination of trapezius compared with no feedback implying a more uneven spatial distribution of the biomechanical load. The study introduced new aspects in relation to the potential benefit of superimposed muscle contraction in relation to the spatial organization of muscle activity during computer work. PMID:20512502

  20. Oral nutritional supplement fortified with beta-alanine improves physical working capacity in older adults: a randomized, placebo-controlled study.

    PubMed

    McCormack, William P; Stout, Jeffrey R; Emerson, Nadia S; Scanlon, Tyler C; Warren, Ashlee M; Wells, Adam J; Gonzalez, Adam M; Mangine, Gerald T; Robinson, Edward H; Fragala, Maren S; Hoffman, Jay R

    2013-09-01

    This study examined the effects of an oral nutritional supplement fortified with two different doses of beta-alanine on body composition, muscle function and physical capacity in older adults. Using a double-blind placebo controlled design, 60 men and women (age ± SD = 70.7 ± 6.2 yrs) were randomly assigned to one of three treatment groups: 1) oral nutritional supplement (ONS; n = 20) (8 oz; 230 kcal; 12 g PRO; 31 g CHO; 6 g FAT), 2) ONS plus 800 mg beta-alanine (ONS800; n = 19), and 3) ONS plus 1200 mg beta-alanine (ONS1200; n = 21). Treatments were consumed twice per day for 12 weeks. At pre- and post-supplementation period, participants performed a discontinuous, submaximal cycle ergometry test to determine physical working capacity at fatigue threshold (PWCFT). Fat mass, total body and arm lean soft tissue mass (ALSTM) were measured with DEXA while muscle strength was assessed with handgrip dynamometry (GRIP) and 30-s sit-to-stand (STS) was used to measure lower body functionality. Muscle quality (MQ) was calculated with GRIPmax and DEXA derived ALSTM [GRIP (kg)·ALSTM (kg)(-1)]. Two-way analysis of variance was used to compare pre- to post-supplementation measures and group differences. There were 16 dropouts over the duration of the study. Final group sizes were ONS = 16 (m = 11, w = 5), ONS800 = 15 (m = 5, w = 10), and ONS1200 = 13 (m = 6, w = 7). No significant changes were observed for body composition or GRIP values pre to post. Significant increases in PW(CFT) were seen in ONS1200 (13.6%) and ONS800 (17.8%) pre- to post-supplementation (p < 0.05). These changes were significantly greater (p < 0.05) than the changes in ONS (-6.3%). ONS1200 and ONS had significant increases in STS (22.2 and 10.7%, respectively). While ONS significantly increased in STS, no differences (p > 0.05) in change scores were found between ONS and ONS800. ONS fortified with beta-alanine may improve physical working capacity, muscle quality and function in older men and women

  1. Low working memory capacity is only spuriously related to poor reading comprehension.

    PubMed

    Van Dyke, Julie A; Johns, Clinton L; Kukona, Anuenue

    2014-06-01

    Accounts of comprehension failure, whether in the case of readers with poor skill or when syntactic complexity is high, have overwhelmingly implicated working memory capacity as the key causal factor. However, extant research suggests that this position is not well supported by evidence on the span of active memory during online sentence processing, nor is it well motivated by models that make explicit claims about the memory mechanisms that support language processing. The current study suggests that sensitivity to interference from similar items in memory may provide a better explanation of comprehension failure. Through administration of a comprehensive skill battery, we found that the previously observed association of working memory with comprehension is likely due to the collinearity of working memory with many other reading-related skills, especially IQ. In analyses which removed variance shared with IQ, we found that receptive vocabulary knowledge was the only significant predictor of comprehension performance in our task out of a battery of 24 skill measures. In addition, receptive vocabulary and non-verbal memory for serial order-but not simple verbal memory or working memory-were the only predictors of reading times in the region where interference had its primary affect. We interpret these results in light of a model that emphasizes retrieval interference and the quality of lexical representations as key determinants of successful comprehension. PMID:24657820

  2. Low working memory capacity is only spuriously related to poor reading comprehension

    PubMed Central

    Van Dyke, Julie A.; Johns, Clinton L.; Kukona, Anuenue

    2014-01-01

    Accounts of comprehension failure, whether in the case of readers with poor skill or when syntactic complexity is high, have overwhelmingly implicated working memory capacity as the key causal factor. However, extant research suggests that this position is not well supported by evidence on the span of active memory during online sentence processing, nor is it well motivated by models that make explicit claims about the memory mechanisms that support language processing. The current study suggests that sensitivity to interference from similar items in memory may provide a better explanation of comprehension failure. Through administration of a comprehensive skill battery, we found that the previously observed association of working memory with comprehension is likely due to the collinearity of working memory with many other reading-related skills, especially IQ. In analyses which removed variance shared with IQ, we found that receptive vocabulary knowledge was the only significant predictor of comprehension performance in our task out of a battery of 24 skill measures. In addition, receptive vocabulary and non-verbal memory for serial order—but not simple verbal memory or working memory—were the only predictors of reading times in the region where interference had its primary affect. We interpret these results in light of a model that emphasizes retrieval interference and the quality of lexical representations as key determinants of successful comprehension. PMID:24657820

  3. Mechanical power and work of cat soleus, gastrocnemius and plantaris muscles during locomotion: possible functional significance of muscle design and force patterns.

    PubMed

    Prilutsky, B I; Herzog, W; Allinger, T L

    1996-04-01

    Electrical activity, forces, power and work of the soleus (SO), the gastrocnemius (GA) and the plantaris (PL) muscles were measured during locomotion in the cat in order to study the functional role of these ankle extensor muscles. Forces and electrical activity (EMG) of the three muscles were measured using home-made force transducers and bipolar, indwelling wire electrodes, respectively, for walking and trotting at speeds of 0.4 to 1.8 m s-1 on a motor-driven treadmill. Video records and a geometrical model of the cat hindlimb were used for calculating the rates of change in lengths of the SO, GA and PL muscles. The instantaneous maximum possible force that can be produced by a muscle at a given fibre length and the rate of change in fibre length (termed contractile abilities) were estimated for each muscle throughout the step cycle. Fibre lengths of the SO, GA and PL were calculated using a planar, geometrical muscle model, measured muscle forces and kinematics, and morphological measurements from the animal after it had been killed. Mechanical power and work of SO, GA and PL were calculated for 144 step cycles. The contribution of the positive work done by the ankle extensor muscles of one hindlimb to the increase of the total mechanical energy of the body (estimated from values in the literature) increased from 4-11% at speeds of locomotion of 0.4 and 0.8 m s-1 to 7-16% at speeds of 1.2 m s-1 and above. The relative contributions of the negative and positive work to the total negative and positive work done by the three ankle extensor muscles increased for GA, decreased for SO and remained about the same for PL, with increasing speeds of locomotion. At speeds of 0.4-0.8 m s-1, the positive work normalized to muscle mass was 7.5-11.0 J kg-1, 1.9-3.0 J kg-1 and 5.3-8.4 J kg-1 for SO, GA and PL, respectively. At speeds of 1.2-1.8 m s-1, the corresponding values were 9.8-16.7 J kg-1, 6.0-10.7 J kg-1 and 13.4-25.0 J kg-1. Peak forces of GA and PL increased and peak

  4. Activation of GPR30 improves exercise capacity and skeletal muscle strength in senescent female Fischer344 × Brown Norway rats.

    PubMed

    Wang, Hao; Alencar, Allan; Lin, Marina; Sun, Xuming; Sudo, Roberto T; Zapata-Sudo, Gisele; Lowe, Dawn A; Groban, Leanne

    2016-06-17

    The molecular mechanisms of muscle weakness and sarcopenia in postmenopausal women are largely unknown. To determine the effect of a new estrogen receptor, GPR30, in the maintenance of exercise capacity and skeletal muscle function in females, the selective GPR30 agonist, G1 (100 μg/kg/day), or vehicle (V, soybean oil) was administered subcutaneously daily (n = 7 per group) to ovariectomized (OVX) 27-month-old Fischer 344 × Brown Norway (F344BN) female rats. Following 8 weeks of treatment, the exercise capacity (treadmill walk time to exhaustion) was reduced in OVX vs. sham rats (5.1 ± 1.4 vs. 11.0 ± 0.9 min, P < 0.05), and chronic G1 restored exercise capacity (12.9 ± 1.2 min; P < 0.05 vs. OVX-V). Similarly, the peak twitch of electrically stimulated soleus muscles was decreased by 22% in OVX vs. sham rats (P < 0.05), and G1 attenuated this decline (P < 0.05). Western blot analysis showed that chronic G1 treatment attenuated OVX-associated decreases in heat shock protein (HSP) 90, HSP70, and HSP27 expressions. In vitro studies using the L6 myoblast cell line demonstrated that G1 increased mRNA levels of HSPs in cultured cells. Collectively, these data demonstrate that the activation of GPR30 mitigates the adverse effects of estrogen loss on exercise capacity and skeletal muscle contractile function in old F344BN rats. The protective effects of GPR30 might be through its upregulation of heat shock proteins in skeletal muscle. PMID:27173878

  5. A comparison of respiratory and peripheral muscle strength, functional exercise capacity, activities of daily living and physical fitness in patients with cystic fibrosis and healthy subjects.

    PubMed

    Arikan, Hulya; Yatar, İlker; Calik-Kutukcu, Ebru; Aribas, Zeynep; Saglam, Melda; Vardar-Yagli, Naciye; Savci, Sema; Inal-Ince, Deniz; Ozcelik, Ugur; Kiper, Nural

    2015-01-01

    There are limited reports that compare muscle strength, functional exercise capacity, activities of daily living (ADL) and parameters of physical fitness of cystic fibrosis (CF) patients with healthy peers in the literature. The purpose of this study was to assess and compare respiratory and peripheral muscle strength, functional exercise capacity, ADL and physical fitness in patients with CF and healthy subjects. Nineteen patients with CF (mean forced expiratory volume in one second-FEV1: 86.56±18.36%) and 20 healthy subjects were included in this study. Respiratory (maximal inspiratory pressure-MIP and maximal expiratory pressure-MEP) and peripheral muscle strength (quadriceps, shoulder abductors and hand grip strength) were evaluated. Functional exercise capacity was determined with 6min walk test (6MWT). ADL was assessed with Glittre ADL test and physical fitness was assessed with Munich fitness test (MFT). There were not any statistically significant difference in MIP, %MIP, MEP and %MEP values between two groups (p>0.05). %Peripheral muscle strength (% quadriceps and shoulder abductors strength), 6MWT distance and %6MWT distance were significantly lower in patients with CF than those of healthy subjects (p<0.05). Glittre ADL-test time was significantly longer in patients with CF than healthy subjects (p<0.05). According to Munich fitness test, the number of bouncing a ball, hanging score, distance of standing vertical jumping and standing vertical jumping score were significantly lower in patients with CF than those of healthy subjects (p<0.05). Peripheral muscle strength, functional exercise capacity, ADL performance and speed, coordination, endurance and power components of physical fitness are adversely affected in mild-severe patients with CF compared to healthy peers. Evaluations must be done in comprehensive manner in patients with CF with all stages. PMID:26241869

  6. The Expression of Carnosine and Its Effect on the Antioxidant Capacity of Longissimus dorsi Muscle in Finishing Pigs Exposed to Constant Heat Stress

    PubMed Central

    Yang, Peige; Hao, Yue; Feng, Jinghai; Lin, Hai; Feng, Yuejin; Wu, Xin; Yang, Xin; Gu, Xianhong

    2014-01-01

    The objective of this study was to assess the effects of constant high ambient temperatures on meat quality, antioxidant capacity, and carnosine expression in longissimus dorsi muscle of finishing pigs. Castrated 24 male DLY (crossbreeds between Landrace×Yorkshire sows and Duroc boars) pigs were allocated to one of three treatments: constant ambient temperature at 22°C and ad libitum feeding (CON, n = 8); constant high ambient temperature at 30°C and ad libitum feeding (H30, n = 8); and constant ambient temperature at 22°C and pair-fed with H30 (PF, n = 8). Meat quality, malondialdehyde (MDA) content, antioxidant capacity, carnosine content, and carnosine synthetase (CARNS1) mRNA expression in longissimus dorsi muscle were measured after three weeks. The results revealed that H30 had lower pH24 h, redness at 45 min, and yellowness at 24 h post-mortem (p<0.05), and higher drip loss at 48 h and lightness at 24 h post-mortem (p<0.01). Constant heat stress disrupted the pro-oxidant/antioxidant balance in longissimus dorsi muscle with higher MDA content (p<0.01) and lower antioxidant capacity (p<0.01). Carnosine content and CARNS1 mRNA expression in longissimus dorsi muscle of H30 pigs were significantly decreased (p<0.01) after three weeks at 30°C. In conclusion, constant high ambient temperatures affect meat quality and antioxidant capacity negatively, and the reduction of muscle carnosine content is one of the probable reasons. PMID:25358371

  7. Common capacity-limited neural mechanisms of selective attention and spatial working memory encoding.

    PubMed

    Fusser, Fabian; Linden, David E J; Rahm, Benjamin; Hampel, Harald; Haenschel, Corinna; Mayer, Jutta S

    2011-09-01

    One characteristic feature of visual working memory (WM) is its limited capacity, and selective attention has been implicated as limiting factor. A possible reason why attention constrains the number of items that can be encoded into WM is that the two processes share limited neural resources. Functional magnetic resonance imaging (fMRI) studies have indeed demonstrated commonalities between the neural substrates of WM and attention. Here we investigated whether such overlapping activations reflect interacting neural mechanisms that could result in capacity limitations. To independently manipulate the demands on attention and WM encoding within one single task, we combined visual search and delayed discrimination of spatial locations. Participants were presented with a search array and performed easy or difficult visual search in order to encode one, three or five positions of target items into WM. Our fMRI data revealed colocalised activation for attention-demanding visual search and WM encoding in distributed posterior and frontal regions. However, further analysis yielded two patterns of results. Activity in prefrontal regions increased additively with increased demands on WM and attention, indicating regional overlap without functional interaction. Conversely, the WM load-dependent activation in visual, parietal and premotor regions was severely reduced during high attentional demand. We interpret this interaction as indicating the sites of shared capacity-limited neural resources. Our findings point to differential contributions of prefrontal and posterior regions to the common neural mechanisms that support spatial WM encoding and attention, providing new imaging evidence for attention-based models of WM encoding. PMID:21781193

  8. Understanding age-related reductions in visual working memory capacity: Examining the stages of change detection

    PubMed Central

    Duda, Bryant; Hussey, Erin; Mason, Emily; Molitor, Robert J.; Woodman, Geoffrey F.; Ally, Brandon A.

    2014-01-01

    Visual working memory (VWM) capacity is reduced in older adults. Research has shown age-related impairments to VWM encoding, but aging is likely to affect multiple stages of VWM. In the present study, we recorded the event-related potentials (ERPs) of younger and older adults during VWM maintenance and retrieval. We measured encoding-stage processing with the P1 component, maintenance-stage processing with the contralateral delay activity (CDA), and retrieval-stage processing by comparing the activity for old and new items (old–new effect). Older adults showed lower behavioral capacity estimates (K) than did younger adults, but surprisingly, their P1 components and CDAs were comparable to those of younger adults. This remarkable dissociation between neural activity and behavior in the older adults indicated that the P1 and CDA did not accurately assess their VWM capacity. However, the neural activity evoked during VWM retrieval yielded results that helped clarify the age-related differences. During retrieval, younger adults showed early old–new effects in frontal and occipital areas and a late central–parietal old–new effect, whereas older adults showed a late right-lateralized parietal old–new effect. The younger adults’ early old–new effects strongly resembled an index of perceptual fluency, suggesting that perceptual implicit memory was activated. The activation of implicit memory could have facilitated the younger adults’ behavior, and the lack of these early effects in older adults may suggest that they have much lower-resolution memory than do younger adults. From these data, we speculated that younger and older adults store the same number of items in VWM, but that younger adults store a higher-resolution representation than do older adults. PMID:24420648

  9. Regulation of metabolism: the rest-to-work transition in skeletal muscle.

    PubMed

    Wilson, David F

    2015-11-01

    Mitochondrial oxidative phosphorylation is programmed to set and maintain metabolic homeostasis, and understanding that program is essential for an integrated view of cellular and tissue metabolism. The behavior predicted by a mechanism-based model for oxidative phosphorylation is compared with that experimentally measured for skeletal muscle when work is initiated. For the model, initiation of work is simulated by imposing a rate of ATP utilization of either 0.6 (equivalent of 13.4 ml O2·100 g tissue(-1)·min(-1) or 6 μmol O2·g tissue(-1)·min(-1)) or 0.3 mM ATP/s. Creatine phosphate ([CrP]) decrease, both experimentally measured and predicted by the model, can be fit to a single exponential. Increase in ATP synthesis begins immediately but can show a "lag period," during which the rate accelerates. The length of the lag period is similar for both experiment and model; in the model, the lag depends on intramitochondrial [NAD(+)]/[NADH], mitochondrial content, and size of the creatine pool ([CrP] + [Cr]) as well as the resting [CrP]/[Cr]. For in vivo conditions, increase in oxygen consumption may be linearly correlated with a decrease in [CrP] and an increase in inorganic phosphate ([Pi]) and [Cr]. The decrease in [CrP], resting and working steady state [CrP], and the increase in oxygen consumption are dependent on the Po2 in the inspired gas (experimental) or tissue Po2 (model). The metabolic behavior predicted by the model is consistent with available experimental measurements in muscle upon initiation of work, with the model providing valuable insight into how metabolic homeostasis is set and maintained. PMID:26394666

  10. Neuronal synchrony reveals working memory networks and predicts individual memory capacity

    PubMed Central

    Palva, J. Matias; Monto, Simo; Kulashekhar, Shrikanth; Palva, Satu

    2010-01-01

    Visual working memory (VWM) is used to maintain sensory information for cognitive operations, and its deficits are associated with several neuropsychological disorders. VWM is based on sustained neuronal activity in a complex cortical network of frontal, parietal, occipital, and temporal areas. The neuronal mechanisms that coordinate this distributed processing to sustain coherent mental images and the mechanisms that set the behavioral capacity limit have remained unknown. We mapped the anatomical and dynamic structures of network synchrony supporting VWM by using a neuro informatics approach and combined magnetoencephalography and electroencephalography. Interareal phase synchrony was sustained and stable during the VWM retention period among frontoparietal and visual areas in α- (10–13 Hz), β- (18–24 Hz), and γ- (30–40 Hz) frequency bands. Furthermore, synchrony was strengthened with increasing memory load among the frontoparietal regions known to underlie executive and attentional functions during memory maintenance. On the other hand, the subjects’ individual behavioral VWM capacity was predicted by synchrony in a network in which the intraparietal sulcus was the most central hub. These data suggest that interareal phase synchrony in the α-, β-, and γ-frequency bands among frontoparietal and visual regions could be a systems level mechanism for coordinating and regulating the maintenance of neuronal object representations in VWM. PMID:20368447

  11. Building community capacity using web-supported work-based learning.

    PubMed

    Pearson, Pauline; Young-Murphy, Lesley; Yaseen, Jonathan; Shiel, Gillian

    2013-02-01

    Health visitors are a central component of policy to create strong, stable families and communities. The programme which is described here is intended to facilitate existing health visitors to gain confidence and extend or renew their skills in building community capacity (BCC). Networking and relationships are essential to effective community development. These are key skills for the health visitor, which along with professional principles support community capacity building. Learning in this programme is self-directed, supported by web-based resources over a 24 week period. Learning mainly takes place in practice. It involves carrying out a work based project through to completion. Participants register online, and follow a series of six phases. Evaluation of the pilot took place during 2011. Three main areas for improvement were identified: reflective software; signposting access to resources; and dealing with workload pressures. Community engagement for health improvement remains an important element of the vision for health visiting. The programme described is a core resource through which health visitors can build the skills and confidence of community groups and staff in other agencies to make a difference to health and wellbeing. PMID:23469737

  12. As Working Memory Grows: A Developmental Account of Neural Bases of Working Memory Capacity in 5- to 8-Year Old Children and Adults.

    PubMed

    Kharitonova, Maria; Winter, Warren; Sheridan, Margaret A

    2015-09-01

    Working memory develops slowly: Even by age 8, children are able to maintain only half the number of items that adults can remember. Neural substrates that support performance on working memory tasks also have a slow developmental trajectory and typically activate to a lesser extent in children, relative to adults. Little is known about why younger participants elicit less neural activation. This may be due to maturational differences, differences in behavioral performance, or both. Here we investigate the neural correlates of working memory capacity in children (ages 5-8) and adults using a visual working memory task with parametrically increasing loads (from one to four items) using fMRI. This task allowed us to estimate working memory capacity limit for each group. We found that both age groups increased the activation of frontoparietal networks with increasing working memory loads, until working memory capacity was reached. Because children's working memory capacity limit was half of that for adults, the plateau occurred at lower loads for children. Had a parametric increase in load not been used, this would have given an impression of less activation overall and less load-dependent activation for children relative to adults. Our findings suggest that young children and adults recruit similar frontoparietal networks at working memory loads that do not exceed capacity and highlight the need to consider behavioral performance differences when interpreting developmental differences in neural activation. PMID:25961641

  13. Role of physiological ClC-1 Cl- ion channel regulation for the excitability and function of working skeletal muscle.

    PubMed

    Pedersen, Thomas Holm; Riisager, Anders; de Paoli, Frank Vincenzo; Chen, Tsung-Yu; Nielsen, Ole Bækgaard

    2016-04-01

    Electrical membrane properties of skeletal muscle fibers have been thoroughly studied over the last five to six decades. This has shown that muscle fibers from a wide range of species, including fish, amphibians, reptiles, birds, and mammals, are all characterized by high resting membrane permeability for Cl(-) ions. Thus, in resting human muscle, ClC-1 Cl(-) ion channels account for ∼80% of the membrane conductance, and because active Cl(-) transport is limited in muscle fibers, the equilibrium potential for Cl(-) lies close to the resting membrane potential. These conditions-high membrane conductance and passive distribution-enable ClC-1 to conduct membrane current that inhibits muscle excitability. This depressing effect of ClC-1 current on muscle excitability has mostly been associated with skeletal muscle hyperexcitability in myotonia congenita, which arises from loss-of-function mutations in the CLCN1 gene. However, given that ClC-1 must be drastically inhibited (∼80%) before myotonia develops, more recent studies have explored whether acute and more subtle ClC-1 regulation contributes to controlling the excitability of working muscle. Methods were developed to measure ClC-1 function with subsecond temporal resolution in action potential firing muscle fibers. These and other techniques have revealed that ClC-1 function is controlled by multiple cellular signals during muscle activity. Thus, onset of muscle activity triggers ClC-1 inhibition via protein kinase C, intracellular acidosis, and lactate ions. This inhibition is important for preserving excitability of working muscle in the face of activity-induced elevation of extracellular K(+) and accumulating inactivation of voltage-gated sodium channels. Furthermore, during prolonged activity, a marked ClC-1 activation can develop that compromises muscle excitability. Data from ClC-1 expression systems suggest that this ClC-1 activation may arise from loss of regulation by adenosine nucleotides and

  14. Three minutes of all-out intermittent exercise per week increases skeletal muscle oxidative capacity and improves cardiometabolic health.

    PubMed

    Gillen, Jenna B; Percival, Michael E; Skelly, Lauren E; Martin, Brian J; Tan, Rachel B; Tarnopolsky, Mark A; Gibala, Martin J

    2014-01-01

    We investigated whether a training protocol that involved 3 min of intense intermittent exercise per week--within a total training time commitment of 30 min including warm up and cool down--could increase skeletal muscle oxidative capacity and markers of health status. Overweight/obese but otherwise healthy men and women (n = 7 each; age = 29±9 y; BMI = 29.8±2.7 kg/m2) performed 18 training sessions over 6 wk on a cycle ergometer. Each session began with a 2 min warm-up at 50 W, followed by 3×20 s "all-out" sprints against 5.0% body mass (mean power output: ∼450-500 W) interspersed with 2 min of recovery at 50 W, followed by a 3 min cool-down at 50 W. Peak oxygen uptake increased by 12% after training (32.6±4.5 vs. 29.1±4.2 ml/kg/min) and resting mean arterial pressure decreased by 7% (78±10 vs. 83±10 mmHg), with no difference between groups (both p<0.01, main effects for time). Skeletal muscle biopsy samples obtained before and 72 h after training revealed increased maximal activity of citrate synthase and protein content of cytochrome oxidase 4 (p<0.01, main effect), while the maximal activity of β-hydroxy acyl CoA dehydrogenase increased in men only (p<0.05). Continuous glucose monitoring measured under standard dietary conditions before and 48-72 h following training revealed lower 24 h average blood glucose concentration in men following training (5.4±0.6 vs. 5.9±0.5 mmol/L, p<0.05), but not women (5.5±0.4 vs. 5.5±0.6 mmol/L). This was associated with a greater increase in GLUT4 protein content in men compared to women (138% vs. 23%, p<0.05). Short-term interval training using a 10 min protocol that involved only 1 min of hard exercise, 3x/wk, stimulated physiological changes linked to improved health in overweight adults. Despite the small sample size, potential sex-specific adaptations were apparent that warrant further investigation. PMID:25365337

  15. Three Minutes of All-Out Intermittent Exercise per Week Increases Skeletal Muscle Oxidative Capacity and Improves Cardiometabolic Health

    PubMed Central

    Gillen, Jenna B.; Percival, Michael E.; Skelly, Lauren E.; Martin, Brian J.; Tan, Rachel B.; Tarnopolsky, Mark A.; Gibala, Martin J.

    2014-01-01

    We investigated whether a training protocol that involved 3 min of intense intermittent exercise per week — within a total training time commitment of 30 min including warm up and cool down — could increase skeletal muscle oxidative capacity and markers of health status. Overweight/obese but otherwise healthy men and women (n = 7 each; age  = 29±9 y; BMI  = 29.8±2.7 kg/m2) performed 18 training sessions over 6 wk on a cycle ergometer. Each session began with a 2 min warm-up at 50 W, followed by 3×20 s “all-out” sprints against 5.0% body mass (mean power output: ∼450–500 W) interspersed with 2 min of recovery at 50 W, followed by a 3 min cool-down at 50 W. Peak oxygen uptake increased by 12% after training (32.6±4.5 vs. 29.1±4.2 ml/kg/min) and resting mean arterial pressure decreased by 7% (78±10 vs. 83±10 mmHg), with no difference between groups (both p<0.01, main effects for time). Skeletal muscle biopsy samples obtained before and 72 h after training revealed increased maximal activity of citrate synthase and protein content of cytochrome oxidase 4 (p<0.01, main effect), while the maximal activity of β-hydroxy acyl CoA dehydrogenase increased in men only (p<0.05). Continuous glucose monitoring measured under standard dietary conditions before and 48–72 h following training revealed lower 24 h average blood glucose concentration in men following training (5.4±0.6 vs. 5.9±0.5 mmol/L, p<0.05), but not women (5.5±0.4 vs. 5.5±0.6 mmol/L). This was associated with a greater increase in GLUT4 protein content in men compared to women (138% vs. 23%, p<0.05). Short-term interval training using a 10 min protocol that involved only 1 min of hard exercise, 3x/wk, stimulated physiological changes linked to improved health in overweight adults. Despite the small sample size, potential sex-specific adaptations were apparent that warrant further investigation. PMID:25365337

  16. Working-memory capacity, proactive interference, and divided attention: limits on long-term memory retrieval.

    PubMed

    Kane, M J; Engle, R W

    2000-03-01

    Two experiments examined how individual differences in working-memory capacity (WM) relate to proactive interference (PI) susceptibility. We tested high and low WM-span participants in a PI-buildup task under single-task or dual-task ("load") conditions. In Experiment 1, a finger-tapping task was imposed during encoding and retrieval of each list; in Experiment 2, tapping was required during encoding or retrieval. In both experiments, low spans showed greater PI than did high spans under no load, but groups showed equivalent PI under divided attention. Load increased PI only for high spans, suggesting they use attention at encoding and retrieval to combat PI. In Experiment 2, only low spans showed a dual-task cost on List 1 memory, before PI built up. Results indicate a role for attentional processing, perhaps inhibitory in nature, at encoding and retrieval, and are discussed with respect to theories of WM and prefrontal cortex function. PMID:10764100

  17. Heritability of preferred thinking styles and a genetic link to working memory capacity.

    PubMed

    Fletcher, Jennifer M; Marks, Anthony D G; Hine, Donald W; Coventry, William L

    2014-12-01

    Genetic and environmental contributions to preferences for rational and experiential thinking were examined in 100 pairs of monozygotic and 73 pairs of same-sex dizygotic Australian twins. Univariate analyses for experiential thinking and working memory capacity (WMC) revealed genetic effects accounted for 44% and 39% of the variability respectively, with non-shared environmental effects accounting for the balance. For rational thinking, the univariate models produced ambiguous results about the relative roles of heritability and shared environment, but a subsequent Cholesky analysis suggested genetic effects accounted for 34%, with the balance, 66%, explained by the non-shared environment. The Cholesky analysis revealed that shared genetic effects accounted for 60%, and non-shared environment accounted for 40% of the relationship between preference for rational thinking and WMC. PMID:25315611

  18. Work capacity and anticipation in A.A. Ukhtomsky's concept of dominance

    NASA Astrophysics Data System (ADS)

    Pavlova, L. P.

    2015-08-01

    This paper presents the results of theoretical and experimental investigations of human activity and anticipation based on A.A. Ukhtomsky's concept of brain dominance - a non-equilibrium system-forming factor in living systems. Facts on the stages of dominance formation are presented in relation to the creative abilities of the human brain and the role of fatigue as a "lever" for increasing systems' work capacity on the basis of "trace exaltation". Individually, specific features of dominantogenesis are compared with variations in behavioural types. On the basis of chronotopic EEG analysis, we delineate cortical dominants that underlie individual specifics of cognitive processes. The relation is shown between anticipation and the "expansion of dominants" - the broadening of "distal perception" in time and space, as framed by A.A. Ukhtomsky.

  19. Interaction effect of response medium and working memory capacity on creative idea generation

    PubMed Central

    Hao, Ning; Yuan, Huan; Cheng, Rui; Wang, Qing; Runco, Mark A.

    2015-01-01

    This study aimed to examine the interaction effect of response medium (i.e., write down ideas and orally report ideas) and working memory capacity (WMC) on creative idea generation. Participants (N = 90) with higher or lower WMC were asked to solve Alternative Uses Task (AUT) problems in the condition of writing down or speaking out ideas. The results showed that fluency of AUT performance was higher in the writing than in the speaking condition. Additionally, participants with higher WMC performed better on AUT fluency than those with lower WMC in the writing condition, while they showed no difference in the speaking condition. Moreover, level of cognitive demand fully mediated the effect of response medium on AUT fluency. Theoretically, these findings indicated the importance of WMC in creative idea generation, which supported the controlled-attention theory of creativity. Practical implications and future directions were discussed. PMID:26528227

  20. Cortical potentials in an auditory oddball task reflect individual differences in working memory capacity

    PubMed Central

    Yurgil, Kate A.; Golob, Edward J.

    2014-01-01

    This study determined whether auditory cortical responses associated with mechanisms of attention vary with individual differences in working memory capacity (WMC) and perceptual load. The operation span test defined subjects with low vs. high WMC, who then discriminated target/nontarget tones while EEG was recorded. Infrequent white noise distracters were presented at midline or ±90° locations, and perceptual load was manipulated by varying nontarget frequency. Amplitude of the N100 to distracters was negatively correlated with WMC. Relative to targets, only high WMC subjects showed attenuated N100 amplitudes to nontargets. In the higher WMC group, increased perceptual load was associated with decreased P3a amplitudes to distracters and longer-lasting negative slow wave to nontargets. Results show that auditory cortical processing is associated with multiple facets of attention control related to WMC and possibly higher-level cognition. PMID:24016201

  1. The Influence of Passive Acceleration and Exercise+Acceleration on Work Capacity and Orthostasis

    NASA Technical Reports Server (NTRS)

    Simonson, S. R.; Cowell, S. A.; Stocks, J. M.; Biagini, H. W.; Vener, J. M.; Evetts, S. N.; Bailey, K. N.; Evans, J.; Knapp, C.; Greenleaf, J. E.

    1999-01-01

    The losses of aerobic power and orthostatic tolerance are significant effects of manned C) spaceflight that can negatively impact crew health and safety. Daily acceleration and aerobic training may ameliorate these effects. To determine the influence of passive intermittent +Gz acceleration (PA) training and active acceleration + interval exercise (AE) training on work 0 0 capacity and the acute (1 min) response to 70 deg head-up tilt, 6 men (X-Bar SD: age, 33 +/- 6 y; height, 178.3 +/- 4.6 cm; mass, 86.3 +/- 6.6 kg) participated in two 3-wk training protocols. It was hypothesized that PA and AE training would improve orthostatic tolerance and that the addition of aerobic conditioning, would not alter this effect.

  2. The capacity for ethical decisions: the relationship between working memory and ethical decision making.

    PubMed

    Martin, April; Bagdasarov, Zhanna; Connelly, Shane

    2015-04-01

    Although various models of ethical decision making (EDM) have implicitly called upon constructs governed by working memory capacity (WMC), a study examining this relationship specifically has not been conducted. Using a sense making framework of EDM, we examined the relationship between WMC and various sensemaking processes contributing to EDM. Participants completed an online assessment comprised of a demographic survey, intelligence test, various EDM measures, and the Automated Operation Span task to determine WMC. Results indicated that WMC accounted for unique variance above and beyond ethics education, exposure to ethical issues, and intelligence in several sensemaking processes. Additionally, a marginally significant effect of WMC was also found with reference to EDM. Individual differences in WMC appear likely to play an important role in the ethical decision-making process, and future researchers may wish to consider their potential influences. PMID:24744116

  3. Interaction effect of response medium and working memory capacity on creative idea generation.

    PubMed

    Hao, Ning; Yuan, Huan; Cheng, Rui; Wang, Qing; Runco, Mark A

    2015-01-01

    This study aimed to examine the interaction effect of response medium (i.e., write down ideas and orally report ideas) and working memory capacity (WMC) on creative idea generation. Participants (N = 90) with higher or lower WMC were asked to solve Alternative Uses Task (AUT) problems in the condition of writing down or speaking out ideas. The results showed that fluency of AUT performance was higher in the writing than in the speaking condition. Additionally, participants with higher WMC performed better on AUT fluency than those with lower WMC in the writing condition, while they showed no difference in the speaking condition. Moreover, level of cognitive demand fully mediated the effect of response medium on AUT fluency. Theoretically, these findings indicated the importance of WMC in creative idea generation, which supported the controlled-attention theory of creativity. Practical implications and future directions were discussed. PMID:26528227

  4. Science misconceptions and working memory capacity among Saudi adolescents: A neo-Piagetian investigation

    NASA Astrophysics Data System (ADS)

    Al-Jubaili, Ahmad Yahya

    This study was designed to investigate the relationships between science misconceptions and working memory capacity in Saudi adolescent students. The participants in this study were from eleventh and twelfth grades; both male and female students and natural and social science Saudi comprised the sample. Also investigated in this study were the conceptions and misconceptions of gravity in a non-European culture, that is Saudi culture, and the variables that differentiated those individuals who could overcome their misconceptions from those who could not and the gender differences in science misconceptions in the context of Saudi culture. Another important focus of this study was to investigate the participants' responses and explanations on the science misconceptions tasks (WLT and EGT). As would be expected, there was a strong correlation between WLT and EGT in the responses of students and their explanations. The most successful students on the WLT and EGT were natural science students rather than social science students, and there were no gender differences between male and female participants. Also investigated were the correlations between the dependent variables (i.e., the WLT and EGT; the measures of science misconceptions) and the independent variables, which were the visual working memory capacity tasks (i.e., FIT and VPS), the field independence/dependence (FASP), students' grade point average (GPA), age, academic major, gender, and grade level. It was found that both of the dependent variables (i.e., the WLT and EGT) correlated significantly with the same independent variables, the FIT, VPS, FASP, academic major, and students' grade point average (GPA).

  5. Concurrent cognitive task may improve motor work performance and reduce muscle fatigue.

    PubMed

    Evstigneeva, Maria; Aleksandrov, Aleksandr; Mathiassen, Svend Erik; Lyskov, Eugene

    2012-01-01

    Performance of certain cognitive tasks either during physical load or in rest pauses between boosts might lead to slowing of muscle fatigue and fatigue related decline in performance. Seventeen right-handed healthy volunteers (age 24 ± 1.4, 8 males) participated in this study, aiming to investigate the effect of the level of the cognitive information processing - 1) passive perception of audio stimuli, 2) active stimuli discrimination, 3) active stimuli discrimination following motor response - on motor task performance (handgrip test 30% and 7% of MVC) and muscle fatigue development. Cognitive tasks show the following effects on motor work: i) Perceived fatigue during 30 % MVC (fatiguing) condition developed slower if participant pressed button in response to deviant acoustic stimuli, as compared to passive listening. Counting task, an active task without motor component, took the intermediate position and did not differ significantly from two other cognitive tasks. ii) MVC after 30% MVC (fatiguing) condition tended to decrease stronger when accompanied with passive listening in comparison with both active tasks. iii) Motor task performance during 30% MVC (fatiguing) condition was better for active cognitive task with motor component than for passive task. Active task without motor component took the intermediate position and did not differ significantly from both the other cognitive tasks. PMID:22317158

  6. Working memory capacity and retrieval limitations from long-term memory: an examination of differences in accessibility.

    PubMed

    Unsworth, Nash; Spillers, Gregory J; Brewer, Gene A

    2012-01-01

    In two experiments, the locus of individual differences in working memory capacity and long-term memory recall was examined. Participants performed categorical cued and free recall tasks, and individual differences in the dynamics of recall were interpreted in terms of a hierarchical-search framework. The results from this study are in accordance with recent theorizing suggesting a strong relation between working memory capacity and retrieval from long-term memory. Furthermore, the results also indicate that individual differences in categorical recall are partially due to differences in accessibility. In terms of accessibility of target information, two important factors drive the difference between high- and low-working-memory-capacity participants. Low-working-memory-capacity participants fail to utilize appropriate retrieval strategies to access cues, and they also have difficulty resolving cue overload. Thus, when low-working-memory-capacity participants were given specific cues that activated a smaller set of potential targets, their recall performance was the same as that of high-working-memory-capacity participants. PMID:22800472

  7. Effects of Below-knee Assembly Work at Different Reach Distances on Upper-extremity Muscle Activity.

    PubMed

    Shin, Seung-Je; Yoo, Won-Gyu

    2014-08-01

    [Purpose] We investigated upper-extremity muscle activity during below-knee assembly work performed by healthy adults at three different reach distances evaluate the physical risk factors associated with neck and shoulder disorders of reach distances. [Subjects] Sixteen young male workers were recruited. [Methods] Activities of the right upper trapezius, anterior deltoid, and biceps brachii muscles were measured during below-knee assembly work at the three different reach distances. [Results] The normalized EMG data of the upper trapezius, anterior deltoid, and biceps brachii muscles generally increased significantly as the reach distance at which the assembly work was performed increased. [Conclusion] Below-knee workers should engage in work that involves shorter (nearer) reach distances. PMID:25202196

  8. Estimate of Maximum Underground Working Gas Storage Capacity in the United States

    EIA Publications

    2006-01-01

    This report examines the aggregate maximum capacity for U.S. natural gas storage. Although the concept of maximum capacity seems quite straightforward, there are numerous issues that preclude the determination of a definitive maximum volume. The report presents three alternative estimates for maximum capacity, indicating appropriate caveats for each.

  9. Validity and relevance of the pack hike wildland firefighter work capacity test: a review.

    PubMed

    Petersen, Aaron; Payne, Warren; Phillips, Matthew; Netto, Kevin; Nichols, David; Aisbett, Brad

    2010-10-01

    Fighting wildland fire is a physically demanding occupation. Wildland firefighters need to be physically fit to work safely and productively. To determine whether personnel are fit for duty, many firefighting agencies employ physical competency tests, such as the pack hike test (PHT). The PHT involves a 4.83-km hike over level terrain carrying a 20.4-kg pack within a 45-min period. The PHT was devised to test the job readiness of US wildland firefighters but is also currently used by some fire agencies in Australia and Canada. This review discusses the history and development of the PHT with emphasis on the process of test validation. Research-based training advice for the PHT is given, as well as discussion of the risks associated with completing the PHT. Different versions and modifications to the PHT have emerged in recent years and these are discussed with regard to their validity. Finally, this review addresses the relevance and validity of the PHT for Australian and Canadian wildland firefighters. STATEMENT OF RELEVANCE: This paper reviews the history, development and validity of the PHT, an internationally recognised and utilised wildland firefighter work capacity test. It is concluded that while the PHT has general content validity for US wildland firefighters, verification of its reliability, criterion and construct validity is still needed. PMID:20865610

  10. Viability, Differentiation Capacity, and Detectability of Super-Paramagnetic Iron Oxide-Labeled Muscle Precursor Cells for Magnetic-Resonance Imaging

    PubMed Central

    Azzabi, Fahd; Rottmar, Markus; Jovaisaite, Virginija; Rudin, Markus; Sulser, Tullio; Boss, Andreas

    2015-01-01

    Cell therapies are a promising approach for the treatment of a variety of human conditions including stress urinary incontinence, but their success greatly depends on the biodistribution, migration, survival, and differentiation of the transplanted cells. Noninvasive in vivo cell tracking therefore presents an important aspect for translation of such a procedure into the clinics. Upon labeling with superparamagnetic iron oxide (SPIO) nanoparticles, cells can be tracked by magnetic resonance imaging (MRI), but possible adverse effect of the labeling have to be considered when labeling stem cells with SPIOs. In this study, human muscle precursor cells (hMPC) were labeled with increasing concentrations of SPIO nanoparticles (100–1600 μg/mL) and cell viability and differentiation capacity upon labeling was assessed in vitro. While a linear dependence between cell viability and nanoparticle concentration could be observed, differentiation capacity was not affected by the presence of SPIOs. Using a nude mouse model, a concentration (400 μg/mL) could be defined that allows reliable detection of hMPCs by MRI but does not influence myogenic in vivo differentiation to mature and functional muscle tissue. This suggests that such an approach can be safely used in a clinical setting to track muscle regeneration in patients undergoing cell therapy without negative effects on the functionality of the bioengineered muscle. PMID:24988198

  11. Vitamin E and C supplementation reduces oxidative stress, improves antioxidant enzymes and positive muscle work in chronically loaded muscles of aged rats

    PubMed Central

    Ryan, Michael J.; Dudash, Holly J.; Docherty, Megan; Geronilla, Kenneth B.; Baker, Brent A.; Haff, G. Gregory; Cutlip, Robert G.; Alway, Stephen E.

    2010-01-01

    Aging is associated with increased oxidative stress. Muscle levels of oxidative stress are further elevated with exercise. The purpose of this study was to determine if dietary antioxidant supplementation would improve muscle function and cellular markers of oxidative stress in response to chronic repetitive loading in aging. The dorsiflexors of the left limb of aged and young adult Fischer 344 Brown x Norway rats were loaded 3 times weekly for 4.5 weeks using 80 maximal stretch-shortening contractions per session. The contralateral limb served as the intra-animal control. The rats were randomly assigned to a diet supplemented with Vitamin E and Vitamin C or normal non-supplemented rat chow. Biomarkers of oxidative stress were measured in the tibialis anterior muscle. Repetitive loading exercise increased maximal isometric force, negative and positive work in the dorsiflexors of young adult rats. Only positive work increased in the aged animals that were supplemented with Vitamin E and C. Markers of oxidative stress (H2O2, total GSH, GSH/GSSG ratio, malondialdehyde and 8-OHdG) increased in the tibialis anterior muscles from aged and young adult animals with repetitive loading, but Vitamin E and C supplements attenuated this increase. MnSOD activity increased with supplementation in the young adult animals. CuZnSOD and catalase activity increased with supplementation in young adult and aged animals and GPx activity increased with exercise in the non-supplemented young adult and aged animals. The increased levels of endogenous antioxidant enzymes after Vitamin E and C supplementation appear to be regulated by post-transcriptional modifications that are affected differently by age, exercise, and supplementation. These data suggest that antioxidant supplementation improves indices of oxidative stress associated with repetitive loading exercise and aging and improve the positive work output of muscles in aged rodents. PMID:20705127

  12. REGULATION OF ERK EXPRESSION BY MUSCLE IGF-I "IN VIVO" DETERMINES THE CAPACITY FOR MYONUCLEAR PROLIFERATION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Local IGF-I enhances muscle growth by stimulating protein synthesis and myonuclear accretion. This response, however, is not sustained upon chronic exposure to high levels of IGF-I, and we determined previously that this limited response was associated with a decrease in the amount of muscle ERK pro...

  13. No Evidence for a Fixed Object Limit in Working Memory: Spatial Ensemble Representations Inflate Estimates of Working Memory Capacity for Complex Objects

    ERIC Educational Resources Information Center

    Brady, Timothy F.; Alvarez, George A.

    2015-01-01

    A central question for models of visual working memory is whether the number of objects people can remember depends on object complexity. Some influential "slot" models of working memory capacity suggest that people always represent 3-4 objects and that only the fidelity with which these objects are represented is affected by object…

  14. Comparative Proteomic Profiling of Divergent Phenotypes for Water Holding Capacity across the Post Mortem Ageing Period in Porcine Muscle Exudate

    PubMed Central

    Di Luca, Alessio; Hamill, Ruth M.; Mullen, Anne Maria; Slavov, Nikolai; Elia, Giuliano

    2016-01-01

    Two dimensional Difference Gel Electrophoresis (2-D DIGE) and mass spectrometry were applied to investigate the changes in metabolic proteins that occur over a seven day (day 1, 3 and 7) post mortem ageing period in porcine centrifugal exudate from divergent meat quality phenotypes. The objectives of the research were to enhance our understanding of the phenotype (water holding capacity) and search for biomarkers of this economically significant pork quality attribute. Major changes in protein abundance across nine phenotype-by-time conditions were observed. Proteomic patterns were dominated by post mortem ageing timepoint. Using a machine learning algorithm (l1-regularized logistic regression), a model was derived with the ability to discriminate between high drip and low drip phenotypes using a subset of 25 proteins with an accuracy of 63%. Models discriminating between divergent phenotypes with accuracy of 72% and 73% were also derived comparing respectively, high drip plus intermediate phenotype (considered as one phenotype) versus low drip and comparing low drip plus intermediate phenotype (considered as one phenotype) versus high drip. In all comparisons, the general classes of discriminatory proteins identified include metabolic enzymes, stress response, transport and structural proteins. In this research we have enhanced our understanding of the protein related processes underpinning this phenotype and provided strong data to work toward development of protein biomarkers for water holding capacity. PMID:26950297

  15. Shorebirds' seasonal adjustments in thermogenic capacity are reflected by changes in body mass: how preprogrammed and instantaneous acclimation work together.

    PubMed

    Vézina, François; Dekinga, Anne; Piersma, Theunis

    2011-09-01

    Phenotypic flexibility in shorebirds has been studied mainly in the context of adjustments to migration and to quality of food; little is known on how birds adjust their phenotype to harsh winter conditions. We showed earlier that red knot (Calidris canutus islandica) can acclimate to cold by elevating body mass. This goes together with larger pectoral muscles, i.e., greater shivering machinery, and thus, better thermogenic capacity. Here, we present results of a yearlong experiment with indoor captive knots to determine whether this strategy is part of their natural seasonal phenotypic cycle. We maintained birds under three thermal regimes: constant cold (5 °C), constant thermoneutrality (25 °C) and natural seasonal variation between these extremes (9-22 °C). Each month we measured variables related to the birds' endurance to cold and physiological maintenance [body mass, thickness of pectoral muscles, summit metabolic rate (M(sum)), food intake, gizzard size, basal metabolic rate (BMR)]. Birds from all treatments expressed synchronized and comparable variation in body mass in spite of thermal treatments, with a 17-18% increase between the warmest and coldest months of the year; which appeared regulated by an endogenous driver. In addition, birds living in the cold exhibited a 10% higher average body mass than did those maintained at thermoneutrality. Thickness of the pectoral muscle tracked changes in body mass in all treatments and likely contributed to greater capacity for shivering in heavier birds. Consequently, M(sum) was 13% higher in cold-acclimated birds compared to those experiencing no thermoregulation costs. However, our data also suggest that part of maximal heat production comes from nonshivering processes. Birds facing cold conditions ate up to 25% more food than did birds under thermoneutral conditions, yet did not develop larger gizzards. Seasonal variation in BMR followed changes in body mass, probably reflecting changes in mass of

  16. Effects of Working Memory Capacity on Metacognitive Monitoring: A Study of Group Differences Using a Listening Span Test

    PubMed Central

    Komori, Mie

    2016-01-01

    Monitoring is an executive function of working memory that serves to update novel information, focusing attention on task-relevant targets, and eliminating task-irrelevant noise. The present research used a verbal working memory task to examine how working memory capacity limits affect monitoring. Participants performed a Japanese listening span test that included maintenance of target words and listening comprehension. On each trial, participants responded to the target word and then immediately estimated confidence in recall performance for that word (metacognitive judgment). The results confirmed significant differences in monitoring accuracy between high and low capacity groups in a multi-task situation. That is, confidence judgments were superior in high vs. low capacity participants in terms of absolute accuracy and discrimination. The present research further investigated how memory load and interference affect underestimation of successful recall. The results indicated that the level of memory load that reduced word recall performance and led to an underconfidence bias varied according to participants' memory capacity. In addition, irrelevant information associated with incorrect true/ false decisions (secondary task) and word recall within the current trial impaired monitoring accuracy in both participant groups. These findings suggest that interference from unsuccessful decisions only influences low, but not high, capacity participants. Therefore, monitoring accuracy, which requires high working memory capacity, improves metacognitive abilities by inhibiting task-irrelevant noise and focusing attention on detecting task-relevant targets or useful retrieval cues, which could improve actual cognitive performance. PMID:26973577

  17. Effects of Working Memory Capacity on Metacognitive Monitoring: A Study of Group Differences Using a Listening Span Test.

    PubMed

    Komori, Mie

    2016-01-01

    Monitoring is an executive function of working memory that serves to update novel information, focusing attention on task-relevant targets, and eliminating task-irrelevant noise. The present research used a verbal working memory task to examine how working memory capacity limits affect monitoring. Participants performed a Japanese listening span test that included maintenance of target words and listening comprehension. On each trial, participants responded to the target word and then immediately estimated confidence in recall performance for that word (metacognitive judgment). The results confirmed significant differences in monitoring accuracy between high and low capacity groups in a multi-task situation. That is, confidence judgments were superior in high vs. low capacity participants in terms of absolute accuracy and discrimination. The present research further investigated how memory load and interference affect underestimation of successful recall. The results indicated that the level of memory load that reduced word recall performance and led to an underconfidence bias varied according to participants' memory capacity. In addition, irrelevant information associated with incorrect true/ false decisions (secondary task) and word recall within the current trial impaired monitoring accuracy in both participant groups. These findings suggest that interference from unsuccessful decisions only influences low, but not high, capacity participants. Therefore, monitoring accuracy, which requires high working memory capacity, improves metacognitive abilities by inhibiting task-irrelevant noise and focusing attention on detecting task-relevant targets or useful retrieval cues, which could improve actual cognitive performance. PMID:26973577

  18. The effect of working memory capacity limitations on the intuitive assessment of correlation: amplification, attenuation, or both?

    PubMed

    Cahan, Sorel; Mor, Yaniv

    2007-03-01

    This article challenges Yaakov Kareev's (1995a, 2000) argument regarding the positive bias of intuitive correlation estimates due to working memory capacity limitations and its adaptive value. The authors show that, under narrow window theory's primacy effect assumption, there is a considerable between-individual variability of the effects of capacity limitations on the intuitive assessment of correlation, in terms of both sign and magnitude: Limited capacity acts as an amplifier for some individuals and as a silencer for others. Furthermore, the average amount of attenuation exceeds the average amount of amplification, and the more so, the smaller the capacity. Implications regarding the applicability and contribution of the bias notion in this context and the evaluation of the adaptive value of capacity limitations are discussed. PMID:17352623

  19. The Effect of an Executive Functioning Training Program on Working Memory Capacity and Intrusive Thoughts.

    PubMed

    Bomyea, Jessica; Amir, Nader

    2011-12-01

    Recurrent intrusive thoughts are apparent across numerous clinical disorders, including depression (i.e., rumination) and anxiety disorders (e.g., worry, obsessions; Brewin et al. 2010). Theoretical accounts of intrusive thoughts suggest that individual differences in executive functioning, specifically poor inhibitory control, may account for the persistence of these thoughts in some individuals (e.g., Anderson and Levy 2009). The present study examined the causal effect of inhibitory control on intrusive thoughts by experimentally manipulating inhibition requirements in a working memory capacity (WMC) task and evaluating the effect of this training on intrusive thoughts during a thought suppression task. Unselected undergraduate participants were randomly assigned to repeatedly practice a task requiring either high inhibitory control (training condition) or low inhibitory control (control condition). Results indicated that individuals in the training condition demonstrated significantly greater WMC performance improvements from pre to post assessment relative to the control group. Moreover, individuals in the training group experienced fewer intrusions during a thought suppression task. These results provide support for theoretical accounts positing a relationship between inhibitory control and intrusive thoughts. Moreover, improving inhibitory control through computerized training programs may have clinical utility in disorders characterized by recurrent intrusive thoughts (e.g., depression, PTSD). PMID:22514357

  20. Arousal, working memory capacity, and sexual decision-making in men.

    PubMed

    Spokes, Tara; Hine, Donald W; Marks, Anthony D G; Quain, Peter; Lykins, Amy D

    2014-08-01

    This study investigated whether working memory capacity (WMC) moderated the relationship between physiological arousal and sexual decision making. A total of 59 men viewed 20 consensual and 20 non-consensual images of heterosexual interaction while their physiological arousal levels were recorded using skin conductance response. Participants also completed an assessment of WMC and a date-rape analogue task for which they had to identify the point at which an average Australian male would cease all sexual advances in response to verbal and/or physical resistance from a female partner. Participants who were more physiologically aroused by and spent more time viewing the non-consensual sexual imagery nominated significantly later stopping points on the date-rape analogue task. Consistent with our predictions, the relationship between physiological arousal and nominated stopping point was strongest for participants with lower levels of WMC. For participants with high WMC, physiological arousal was unrelated to nominated stopping point. Thus, executive functioning ability (and WMC in particular) appears to play an important role in moderating men's decision making with regard to sexually aggressive behavior. PMID:24696385

  1. Fronto-parietal network oscillations reveal relationship between working memory capacity and cognitive control

    PubMed Central

    Gulbinaite, Rasa; van Rijn, Hedderik; Cohen, Michael X

    2014-01-01

    Executive-attention theory proposes a close relationship between working memory capacity (WMC) and cognitive control abilities. However, conflicting results are documented in the literature, with some studies reporting that individual variations in WMC predict differences in cognitive control and trial-to-trial control adjustments (operationalized as the size of the congruency effect and congruency sequence effects, respectively), while others report no WMC-related differences. We hypothesized that brain network dynamics might be a more sensitive measure of WMC-related differences in cognitive control abilities. Thus, in the present study, we measured human EEG during the Simon task to characterize WMC-related differences in the neural dynamics of conflict processing and adaptation to conflict. Although high- and low-WMC individuals did not differ behaviorally, there were substantial WMC-related differences in theta (4–8 Hz) and delta (1–3 Hz) connectivity in fronto-parietal networks. Group differences in local theta and delta power were relatively less pronounced. These results suggest that the relationship between WMC and cognitive control abilities is more strongly reflected in large-scale oscillatory network dynamics than in spatially localized activity or in behavioral task performance. PMID:25324759

  2. Electrophysiological measures of resting state functional connectivity and their relationship with working memory capacity in childhood.

    PubMed

    Barnes, Jessica J; Woolrich, Mark W; Baker, Kate; Colclough, Giles L; Astle, Duncan E

    2016-01-01

    Functional connectivity is the statistical association of neuronal activity time courses across distinct brain regions, supporting specific cognitive processes. This coordination of activity is likely to be highly important for complex aspects of cognition, such as the communication of fluctuating task goals from higher-order control regions to lower-order, functionally specific regions. Some of these functional connections are identifiable even when relevant cognitive tasks are not being performed (i.e. at rest). We used magnetoencephalographic recordings projected into source space to demonstrate that resting state networks in childhood have electrophysiological underpinnings that are evident in the spontaneous fluctuations of oscillatory brain activity. Using the temporal structure of these oscillatory patterns we were able to identify a number of functional resting state networks analogous to those reported in the adult literature. In a second analysis we fused this dynamic temporal information with the spatial information from a functional magnetic resonance imaging analysis of functional connectivity, to demonstrate that inter-subject variability in these electrophysiological measures of functional connectivity is correlated with individual differences in cognitive ability: the strength of connectivity between a fronto-parietal network and lower-level processing areas in inferior temporal cortex was associated with spatial working memory capacity, as measured outside the scanner with educationally relevant standardized assessments. This study represents the first exploration of the electrophysiological mechanisms underpinning resting state functional connectivity in source space in childhood, and the extent to which the strength of particular connections is associated with cognitive ability. PMID:25782537

  3. Working memory capacity and Stroop interference: global versus local indices of executive control.

    PubMed

    Meier, Matt E; Kane, Michael J

    2013-05-01

    Two experiments examined the relations among working memory capacity (WMC), congruency-sequence effects, proportion-congruency effects, and the color-word Stroop effect to test whether congruency-sequence effects might inform theoretical claims regarding WMC's prediction of Stroop interference. In Experiment 1, subjects completed either a high-congruency or low-congruency Stroop task that restricted trial-to-trial repetitions of stimulus dimensions to examine WMC's relation to congruency-sequence effects while minimizing bottom-up, stimulus-driven contributions. Congruency-sequence effects and congruency-proportion effects were significant but did not interact. WMC predicted global Stroop interference under low-congruency conditions but neither local congruency-sequence effects nor global Stroop interference under high-congruency conditions, contrary to previous studies (e.g., Kane & Engle, 2003). A high-congruency Stroop task in Experiment 2 removed the Experiment 1 task constraints, and, here, we obtained the typical, global association between WMC and Stroop interference but still no relation between WMC and congruency-sequence effects. We thus examined the methodological differences between Experiments 1 and 2 to determine whether any of these were locally responsible for the global WMC-related differences. They were not, suggesting that the changes between Experiments 1 and 2 created a general task context that engaged (or disengaged) the executive processes associated with WMC. PMID:22774858

  4. The design, performance and analysis of a high work capacity transonic turbine

    SciTech Connect

    Bryce, J.D.; Leversuch, N.P.; Litchfield, M.R.

    1985-10-01

    This paper describes the design and testing of a high work capacity single-stage transonic turbine of aerodynamic duty tailored to the requirements of driving the high-pressure core of a low cost turbofan engine. Aerodynamic loading was high for this duty (..delta..H/U/sup 2/ = 2.1) and a major objective in the design was the control of the resulting transonic flow to achieve good turbine performance. Practical and coolable blading was a design requirement. At the design point (pressure ratio = 4.48), a turbine total to total efficiency of 87.0 percent was measured - this being based on measured shaft power and a tip clearance of 1.4 percent of blade height. In addition, the turbine was comprehensively instrumented to allow measurement of aerofoil surface static pressures on both stator and rotor - the latter being expedited via a rotating scanivalve system. Downstream area traverses were also conducted. Analysis of these measurements indicates that the turbine operates at overall reaction levels lower than design but the rotor blade performs efficiently.

  5. Intrinsic brain indices of verbal working memory capacity in children and adolescents.

    PubMed

    Yang, Zhen; Jutagir, Devika R; Koyama, Maki S; Craddock, R Cameron; Yan, Chao-Gan; Shehzad, Zarrar; Castellanos, F Xavier; Di Martino, Adriana; Milham, Michael P

    2015-10-01

    Working memory (WM) is central to the acquisition of knowledge and skills throughout childhood and adolescence. While numerous behavioral and task-based functional magnetic resonance imaging (fMRI) studies have examined WM development, few have used resting-state fMRI (R-fMRI). Here, we present a systematic R-fMRI examination of age-related differences in the neural indices of verbal WM performance in a cross-sectional pediatric sample (ages: 7-17; n=68), using data-driven approaches. Verbal WM capacity was measured with the digit span task, a commonly used educational and clinical assessment. We found distinct neural indices of digit span forward (DSF) and backward (DSB) performance, reflecting their unique neuropsychological demands. Regardless of age, DSB performance was related to intrinsic properties of brain areas previously implicated in attention and cognitive control, while DSF performance was related to areas less commonly implicated in verbal WM storage (precuneus, lateral visual areas). From a developmental perspective, DSF exhibited more robust age-related differences in brain-behavior relationships than DSB, and implicated a broader range of networks (ventral attention, default, somatomotor, limbic networks)--including a number of regions not commonly associated with verbal WM (angular gyrus, subcallosum). These results highlight the importance of examining the neurodevelopment of verbal WM and of considering regions beyond the "usual suspects". PMID:26299314

  6. Children and adults minimise activated muscle volume by selecting gait parameters that balance gross mechanical power and work demands

    PubMed Central

    Hubel, Tatjana Y.; Usherwood, James R.

    2015-01-01

    ABSTRACT Terrestrial locomotion on legs is energetically expensive. Compared with cycling, or with locomotion in swimming or flying animals, walking and running are highly uneconomical. Legged gaits that minimise mechanical work have previously been identified and broadly match walking and running at appropriate speeds. Furthermore, the ‘cost of muscle force’ approaches are effective in relating locomotion kinetics to metabolic cost. However, few accounts have been made for why animals deviate from either work-minimising or muscle-force-minimising strategies. Also, there is no current mechanistic account for the scaling of locomotion kinetics with animal size and speed. Here, we report measurements of ground reaction forces in walking children and adult humans, and their stance durations during running. We find that many aspects of gait kinetics and kinematics scale with speed and size in a manner that is consistent with minimising muscle activation required for the more demanding between mechanical work and power: spreading the duration of muscle action reduces activation requirements for power, at the cost of greater work demands. Mechanical work is relatively more demanding for larger bipeds – adult humans – accounting for their symmetrical M-shaped vertical force traces in walking, and relatively brief stance durations in running compared with smaller bipeds – children. The gaits of small children, and the greater deviation of their mechanics from work-minimising strategies, may be understood as appropriate for their scale, not merely as immature, incompletely developed and energetically sub-optimal versions of adult gaits. PMID:26400978

  7. Measurement of oxidative metabolism of the working human muscles by near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Yücetaş, Akin; Şayli, Ömer; Karahan, Mustafa; Akin, Ata

    2006-02-01

    Monitoring the oxygenation of skeletal muscle tissues during rest to work transient provides valuable information about the performance of a particular tissue in adapting to aerobic glycolysis. In this paper we analyze the temporal relation of O II consumption with deoxy-hemoglobin (Hb) signals measured by functional Near Infrared Spectroscopy (fNIRS) technique during moderate isotonic forearm finger joint flexion exercise under ischemic conditions and model it with a mono exponential equation with delay. The time constants of fitting equation are questioned under two different work loads and among subjects differing in gender. Ten (6 men and 4 women) subjects performed isotonic forearm finger joint flexion exercise with two different loads. It is shown that under the same load, men and women subjects generate similar time constants and time delays. However, apparent change in time constants and time delays were observed when exercise was performed under different loads. When t-test is applied to compare the outputs for time constants between 0.41202 Watts and 0.90252 Watts, P value of 9.3445x10 -4 < 0.05 is observed which implies that the differences between the time constants are statistically significant. When the same procedure is applied for the time delay comparison, P value of 0.027<0.05 is observed which implies that also the differences between the time delays are statistically significant.

  8. Early auditory evoked potential is modulated by selective attention and related to individual differences in visual working memory capacity.

    PubMed

    Giuliano, Ryan J; Karns, Christina M; Neville, Helen J; Hillyard, Steven A

    2014-12-01

    A growing body of research suggests that the predictive power of working memory (WM) capacity for measures of intellectual aptitude is due to the ability to control attention and select relevant information. Crucially, attentional mechanisms implicated in controlling access to WM are assumed to be domain-general, yet reports of enhanced attentional abilities in individuals with larger WM capacities are primarily within the visual domain. Here, we directly test the link between WM capacity and early attentional gating across sensory domains, hypothesizing that measures of visual WM capacity should predict an individual's capacity to allocate auditory selective attention. To address this question, auditory ERPs were recorded in a linguistic dichotic listening task, and individual differences in ERP modulations by attention were correlated with estimates of WM capacity obtained in a separate visual change detection task. Auditory selective attention enhanced ERP amplitudes at an early latency (ca. 70-90 msec), with larger P1 components elicited by linguistic probes embedded in an attended narrative. Moreover, this effect was associated with greater individual estimates of visual WM capacity. These findings support the view that domain-general attentional control mechanisms underlie the wide variation of WM capacity across individuals. PMID:25000526

  9. Lacking Capacity? How to Work Smart in Teacher Evaluation. Ask the Team

    ERIC Educational Resources Information Center

    Cushing, Ellen

    2013-01-01

    Capacity is a real and pressing challenge for educators tasked with implementing robust evaluation systems that include multiple measures of performance. In response to questions from the field, the Center on Great Teachers and Leaders has gathered emerging strategies from policymakers and practitioners who are grappling with capacity challenges…

  10. Muscle activity and mood state during simulated plant factory work in individuals with cervical spinal cord injury

    PubMed Central

    Okahara, Satoshi; Kataoka, Masataka; Okuda, Kuniharu; Shima, Masato; Miyagaki, Keiko; Ohara, Hitoshi

    2016-01-01

    [Purpose] The present study investigated the physical and mental effects of plant factory work in individuals with cervical spinal cord injury and the use of a newly developed agricultural working environment. [Subjects] Six males with C5–C8 spinal cord injuries and 10 healthy volunteers participated. [Methods] Plant factory work involved three simulated repetitive tasks: sowing, transplantation, and harvesting. Surface electromyography was performed in the dominant upper arm, upper trapezius, anterior deltoid, and biceps brachii muscles. Subjects’ moods were monitored using the Profile of Mood States. [Results] Five males with C6–C8 injuries performed the same tasks as healthy persons; a male with a C5 injury performed fewer repetitions of tasks because it took longer. Regarding muscle activity during transplantation and harvesting, subjects with spinal cord injury had higher values for the upper trapezius and anterior deltoid muscles compared with healthy persons. The Profile of Mood States vigor scores were significantly higher after tasks in subjects with spinal cord injury. [Conclusion] Individuals with cervical spinal cord injury completed the plant factory work, though it required increased time and muscle activity. For individuals with C5–C8 injuries, it is necessary to develop an appropriate environment and assistive devices to facilitate their work. PMID:27134377

  11. AICAR treatment for 14 days normalizes obesity-induced dysregulation of TORC1 signaling and translational capacity in fasted skeletal muscle.

    PubMed

    Drake, Joshua C; Alway, Stephen E; Hollander, John M; Williamson, David L

    2010-12-01

    The aim of this study was to determine the effect of 14 days of 5-aminoimidazole-4-carboxamide-1β-4-ribofuranoside (AICAR) treatment on mammalian target of rapamycin (mTOR) signaling and mTOR-regulated processes (i.e., translation initiation) in obese mouse skeletal muscle. Our hypothesis was that daily treatment (14 days) with AICAR would normalize obesity-induced alterations in skeletal muscle mTOR signaling and mTOR-regulated processes to lean levels and positively affect muscle mass. Fourteen-week-old male, lean (L; 31.3 g body wt) wild-type and ob/ob (O; 59.6 g body wt) mice were injected with the AMP-activated kinase (AMPK) activator AICAR (A) at 0.5 mg·g body wt(-1)·day(-1) or saline control (C) for 14 days. At 24 h after the last injection (including a 12-h fast), all mice were killed, and the plantar flexor complex muscle (gastrocnemius, soleus, and plantaris) was excised for analysis. Muscle mass was lower in OC (159 ± 12 mg) than LC, LA, and OA (176 ± 10, 178 ± 9, and 166 ± 16 mg, respectively) mice, independent of a body weight change. A decrease in obese muscle mass corresponded with higher muscle cross section staining intensity for lipid and glycogen, higher blood glucose and insulin levels, and lower nuclear-enriched fractions for peroxisome proliferator-activated receptor-γ coactivator-1α protein expression in OC skeletal muscle, which was normalized with AICAR treatment. AMPK and acetyl-cocarboxylase phosphorylation was reduced in OC mice and augmented by AICAR treatment in OA mice. Conversely, OC mice displayed higher activation of downstream targets (S6 kinase-1 and ribosomal protein S6) of mTOR and lower raptor-associated mTOR than LC mice, which were reciprocally altered after 14 days of AICAR treatment. Dysregulation of translational capacity was improved in OA mice, as assessed by sucrose density gradient fractionation of ribosomes, total and ribosome-associated RNA content, eukaryotic initiation factor 4F complex formation, and

  12. The deacetylase enzyme SIRT1 is not associated with oxidative capacity in rat heart and skeletal muscle and its overexpression reduces mitochondrial biogenesis

    PubMed Central

    Gurd, Brendon J; Yoshida, Yuko; Lally, James; Holloway, Graham P; Bonen, Arend

    2009-01-01

    Deacetylation of PGC-1α by SIRT1 is thought to be an important step in increasing PGC-1α transcriptional activity, since in muscle cell lines SIRT1 induces PGC-1α protein expression and mitochondrial biogenesis. We examined the relationship between SIRT1 protein and activity, PGC-1α and markers of mitochondrial density, (a) across a range of metabolically heterogeneous skeletal muscles and the heart, and when mitochondrial biogenesis was stimulated by (b) chronic muscle stimulation (7 days) and (c) AICAR administration (5 days), and finally, (d) we also examined the effects of SIRT1 overexpression on mitochondrial biogenesis and PGC-1α. SIRT1 protein and activity were correlated (r= 0.97). There were negative correlations between SIRT1 protein and PGC-1α (r=−0.95), COX IV (r=−0.94) and citrate synthase (r=−0.97). Chronic muscle stimulation and AICAR upregulated PGC-1α protein (22–159%) and oxidative capacity (COX IV, 20–69%); in each instance SIRT1 protein was downregulated by 20–40%, while SIRT1 intrinsic activity was increased. SIRT1 overexpression in rodent muscle increased SIRT1 protein (+240%) and doubled SIRT1 activity, but PGC-1α (−25%), mtTFA (−14%) and COX IV (−10%) proteins were downregulated. Taken altogether these experiments are not consistent with the notion that SIRT1 protein plays an obligatory regulatory role in the process of PGC-1α-mediated mitochondrial biogenesis in mammalian muscle. PMID:19237425

  13. Comparative Effects of Vigorous-Intensity and Low-Intensity Blood Flow Restricted Cycle Training and Detraining on Muscle Mass, Strength, and Aerobic Capacity.

    PubMed

    Kim, Daeyeol; Singh, Harshvardhan; Loenneke, Jeremy P; Thiebaud, Robert S; Fahs, Christopher A; Rossow, Lindy M; Young, Kaelin; Seo, Dong-Il; Bemben, Debra A; Bemben, Michael G

    2016-05-01

    Kim, D, Singh, H, Loenneke, JP, Thiebaud, RS, Fahs, CA, Rossow, LM, Young, K, Seo, D-i, Bemben, DA, and Bemben, MG. Comparative effects of vigorous-intensity and low-intensity blood flow restricted cycle training and detraining on muscle mass, strength, and aerobic capacity. J Strength Cond Res 30(5): 1453-1461, 2016-Traditional high-intensity aerobic training has been shown to improve muscle protein synthesis and aerobic capacity; however, recent research indicates that low-intensity aerobic training with blood flow restriction (BFR) may have similar effects. The purpose of this study was to compare the effects of vigorous-intensity (VI) cycling vs. low-intensity cycling with BFR (LI-BFR) on muscle mass, strength, and aerobic capacity after training and subsequent detraining. Thirty-one physically active subjects were assigned to one of 3 groups: VI (n = 10, 60-70% heart rate reserve [HRR]), LI-BFR (n = 11, 30% HRR with BFR at 160-180 mm Hg), and no exercise control (n = 10, no exercise). Subjects in VI and LI-BFR cycled 3 times per week for 6 weeks (total 18 sessions). Body composition, muscle mass, strength, and aerobic capacity were measured pre, post, and after 3 weeks of detraining. A group × time interaction (p = 0.019) effect for both knee flexion and leg lean mass was found. For both VI and LI-BFR groups, knee flexion strength was significantly increased between pre and post (p = 0.024, p = 0.01) and between pre and 3 week-post (p = 0.039, p = 0.003), respectively. For the LI-BFR group, leg lean mass was significantly increased between pre and 3 week-post (p = 0.024) and between post and 3 week-post (p = 0.013). However, there were no significant differences between groups for any variables. The LI-BFR elicits an increase in the knee flexion muscle strength over time similar to the VI. An increase in the leg lean mass over time was seen in the LI-BFR, but not in VI and CON. PMID:26439780

  14. Return to work following an aquafitness and muscle strengthening program for the low back injured.

    PubMed

    LeFort, S M; Hannah, T E

    1994-11-01

    Our purpose, in this prospective clinical study, was to identify the best predictors of 2-month return to work or retraining for a group of low back injured subjects (n = 40) who completed at least 8 weeks of a community-based rehabilitation program that combined aerobic and flexibility exercise conducted in the water (aquafitness) with muscle strength and endurance training. Baseline demographic characteristics and changes in physical fitness, pain, disability, and psychological well-being during the course of program participation were compared between two groups of low back injured subjects: those who returned to work (RTW) [n = 24], and those who did not (N-RTW) [n = 16]. Subjects in both groups showed comparable improvement in measures of physical fitness at 8 weeks. However, multivariate analyses showed significant between-group differences in self-report measures. The RTW group showed significant improvement in measures of pain, disability, anxiety, and vigor while self-esteem and affect remained stable. The N-RTW group displayed no change in pain and disability variables and had significant deterioration in mean overall psychological well-being over time. The best predictors of return to work using logistic regression analyses were a first injury rather than a repeat injury to the lower back, and stability in self-esteem. Suggestions are offered for further research to examine the benefits of aquafit exercise for the low back injured, for additional interventions for those with a reinjury, and for maintaining or enhancing self-esteem as a treatment goal. PMID:7979938

  15. High-intensity interval training increases in vivo oxidative capacity with no effect on P(i)→ATP rate in resting human muscle.

    PubMed

    Larsen, Ryan G; Befroy, Douglas E; Kent-Braun, Jane A

    2013-03-01

    Mitochondrial ATP production is vital for meeting cellular energy demand at rest and during periods of high ATP turnover. We hypothesized that high-intensity interval training (HIT) would increase ATP flux in resting muscle (VPi→ATP) in response to a single bout of exercise, whereas changes in the capacity for oxidative ATP production (Vmax) would require repeated bouts. Eight untrained men (27 ± 4 yr; peak oxygen uptake = 36 ± 4 ml·kg(-1)·min(-1)) performed six sessions of HIT (4-6 × 30-s bouts of all-out cycling with 4-min recovery). After standardized meals and a 10-h fast, VPi→ATP and Vmax of the vastus lateralis muscle were measured using phosphorus magnetic resonance spectroscopy at 4 Tesla. Measurements were obtained at baseline, 15 h after the first training session, and 15 h after completion of the sixth session. VPi→ATP was determined from the unidirectional flux between Pi and ATP, using the saturation transfer technique. The rate of phosphocreatine recovery (kPCr) following a maximal contraction was used to calculate Vmax. While kPCr and Vmax were unchanged after a single session of HIT, completion of six training sessions resulted in a ∼14% increase in muscle oxidative capacity (P ≤ 0.004). In contrast, neither a single nor six training sessions altered VPi→ATP (P = 0.74). This novel analysis of resting and maximal high-energy phosphate kinetics in vivo in response to HIT provides evidence that distinct aspects of human skeletal muscle metabolism respond differently to this type of training. PMID:23255590

  16. Shoulder and forearm oxygenation and myoelectric activity in patients with work-related muscle pain and healthy subjects.

    PubMed

    Elcadi, Guilherme H; Forsman, Mikael; Aasa, Ulrika; Fahlstrom, Martin; Crenshaw, Albert G

    2013-05-01

    We tested hypotheses of (a) reduced oxygen usage, oxygen recovery, blood flow and oxygen consumption; and (b) increased muscle activity for patients diagnosed with work-related muscle pain (WRMP) in comparison to healthy controls. Oxygenation was measured with near infrared spectroscopy (NIRS), and muscle activity with EMG for the extensor carpi radialis (ECR) and trapezius descendens (TD) muscles. Eighteen patients with diffuse neck-shoulder-arm pain and 17 controls (matched in age and sex) were equipped with NIRS and EMG probes. After determining an individual's maximum voluntary contraction (MVC) force, short-term (20 s) isometric contractions for the ECR and TD of 10, 30, 50 and 70 % MVC generated ∆StO₂ and StO₂% recovery (Rslope) from NIRS, and RMS%max from EMG signals. In addition, upper arm venous (VO) and arterial (AO) occlusions generated slopes of total hemoglobin (HbTslope) and deoxyhemoglobin (HHbslope) for the resting ECR as surrogates of blood flow and oxygen consumption, respectively. Mixed model analyses, t tests, and Mann-Whitney test were used to assess differences between groups. There was no significant difference in MVC between groups for either muscle. Also, ∆StO₂%, Rslope for either muscle, and ECR-HbTslope were not different between groups, thus our hypotheses of reduced oxygen use, recovery, and blood flow for patients were not confirmed. However, patients had a significantly lower ECR-HHbslope confirming our hypothesis of reduced consumption. Further, there was no difference in RMS%max during contractions meaning that the hypothesis of increased activity for patients was not confirmed. When taking into account the number of NIRS variables studied, differences we found between our patient group and healthy controls (i.e., in forearm oxygen consumption and shoulder oxygen saturation level) may be considered modest. Overall our findings may have been impacted by the fact that our patients and controls were similar in muscle strength

  17. Age-related decreases of serum-response factor levels in human mesenchymal stem cells are involved in skeletal muscle differentiation and engraftment capacity.

    PubMed

    Ting, Chiao-Hsuan; Ho, Pai-Jiun; Yen, Betty Linju

    2014-06-01

    Skeletal muscle (SkM) comprise ∼40% of human body weight. Injury or damage to this important tissue can result in physical disability, and in severe cases is difficult for its endogenous stem cell-the satellite cell-to reverse effectively. Mesenchymal stem cells (MSC) are postnatal progenitor/stem cells that possess multilineage mesodermal differentiation capacity, including toward SkM. Adult bone marrow (BM) is the best-studied source of MSCs; however, aging also decreases BMMSC numbers and can adversely affect differentiation capacity. Therefore, we asked whether human sources of developmentally early stage mesenchymal stem cells (hDE-MSCs) isolated from embryonic stem cells, fetal bone, and term placenta could be cellular sources for SkM repair. Under standard muscle-inducing conditions, hDE-MPCs differentiate toward a SkM lineage rather than cardiomyocytic or smooth muscle lineages, as evidenced by increased expression of SkM-associated markers and in vitro myotube formation. In vivo transplantation revealed that SkM-differentiated hDE-MSCs can efficiently incorporate into host SkM tissue in a mouse model of SkM injury. In contrast, adult BMMSCs do not express SkM-associated genes after in vitro SkM differentiation nor engraft in vivo. Further investigation of possible factors responsible for this difference in SkM differentiation potential revealed that, compared with adult BMMSCs, hDE-MSCs expressed higher levels of serum response factor (SRF), a transcription factor critical for SkM lineage commitment. Moreover, knockdown of SRF in hDE-MSCs resulted in decreased expression of SkM-related genes after in vitro differentiation and decreased in vivo engraftment. Our results implicate SRF as a key factor in age-related SkM differentiation capacity of MSCs, and demonstrate that hDE-MSCs are possible candidates for SkM repair. PMID:24576136

  18. Dynamic relation between working memory capacity and speech recognition in noise during the first 6 months of hearing aid use.

    PubMed

    Ng, Elaine H N; Classon, Elisabet; Larsby, Birgitta; Arlinger, Stig; Lunner, Thomas; Rudner, Mary; Rönnberg, Jerker

    2014-01-01

    The present study aimed to investigate the changing relationship between aided speech recognition and cognitive function during the first 6 months of hearing aid use. Twenty-seven first-time hearing aid users with symmetrical mild to moderate sensorineural hearing loss were recruited. Aided speech recognition thresholds in noise were obtained in the hearing aid fitting session as well as at 3 and 6 months postfitting. Cognitive abilities were assessed using a reading span test, which is a measure of working memory capacity, and a cognitive test battery. Results showed a significant correlation between reading span and speech reception threshold during the hearing aid fitting session. This relation was significantly weakened over the first 6 months of hearing aid use. Multiple regression analysis showed that reading span was the main predictor of speech recognition thresholds in noise when hearing aids were first fitted, but that the pure-tone average hearing threshold was the main predictor 6 months later. One way of explaining the results is that working memory capacity plays a more important role in speech recognition in noise initially rather than after 6 months of use. We propose that new hearing aid users engage working memory capacity to recognize unfamiliar processed speech signals because the phonological form of these signals cannot be automatically matched to phonological representations in long-term memory. As familiarization proceeds, the mismatch effect is alleviated, and the engagement of working memory capacity is reduced. PMID:25421088

  19. Validity of the MicroDYN Approach: Complex Problem Solving Predicts School Grades beyond Working Memory Capacity

    ERIC Educational Resources Information Center

    Schweizer, Fabian; Wustenberg, Sascha; Greiff, Samuel

    2013-01-01

    This study examines the validity of the complex problem solving (CPS) test MicroDYN by investigating a) the relation between its dimensions--rule identification (exploration strategy), rule knowledge (acquired knowledge), rule application (control performance)--and working memory capacity (WMC), and b) whether CPS predicts school grades in…

  20. Childhood Poverty, Chronic Stress, and Young Adult Working Memory: The Protective Role of Self-Regulatory Capacity

    ERIC Educational Resources Information Center

    Evans, Gary W.; Fuller-Rowell, Thomas E.

    2013-01-01

    Prior research shows that childhood poverty as well as chronic stress can damage children's executive functioning (EF) capacities, including working memory. However, it is also clear that not all children suffer the same degree of adverse consequences from risk exposure. We show that chronic stress early in life (ages 9-13) links childhood…

  1. Individual Differences in Working Memory Capacity and Episodic Retrieval: Examining the Dynamics of Delayed and Continuous Distractor Free Recall

    ERIC Educational Resources Information Center

    Unsworth, Nash

    2007-01-01

    Two experiments explored the possibility that individual differences in working memory capacity (WMC) partially reflect differences in the size of the search set from which items are retrieved. High- and low-WMC individuals were tested in delayed (Experiment 1) and continuous distractor (Experiment 2) free recall with varying list lengths. Across…

  2. The Effect of Working Memory Capacity Limitations on the Intuitive Assessment of Correlation: Amplification, Attenuation, or Both?

    ERIC Educational Resources Information Center

    Cahan, Sorel; Mor, Yaniv

    2007-01-01

    This article challenges Yaakov Kareev's (1995a, 2000) argument regarding the positive bias of intuitive correlation estimates due to working memory capacity limitations and its adaptive value. The authors show that, under narrow window theory's primacy effect assumption, there is a considerable between-individual variability of the effects of…

  3. Carving Executive Control at Its Joints: Working Memory Capacity Predicts Stimulus-Stimulus, but Not Stimulus-Response, Conflict

    ERIC Educational Resources Information Center

    Meier, Matt E.; Kane, Michael J.

    2015-01-01

    Three experiments examined the relation between working memory capacity (WMC) and 2 different forms of cognitive conflict: stimulus-stimulus (S-S) and stimulus-response (S-R) interference. Our goal was to test whether WMC's relation to conflict-task performance is mediated by stimulus-identification processes (captured by S-S conflict),…

  4. The Generality of Working Memory Capacity: A Latent-Variable Approach to Verbal and Visuospatial Memory Span and Reasoning

    ERIC Educational Resources Information Center

    Kane, Michael J.; Hambrick, David Z.; Tuholski, Stephen W.; Wilhelm, Oliver; Payne, Tabitha W.; Engle, Randall W.

    2004-01-01

    A latent-variable study examined whether verbal and visuospatial working memory (WM) capacity measures reflect a primarily domain-general construct by testing 236 participants in 3 span tests each of verbal WM. visuospatial WM, verbal short-term memory (STM), and visuospatial STM. as well as in tests of verbal and spatial reasoning and general…

  5. Episodic Long-Term Memory of Spoken Discourse Masked by Speech: What Is the Role for Working Memory Capacity?

    ERIC Educational Resources Information Center

    Sorqvist, Patrik; Ronnberg, Jerker

    2012-01-01

    Purpose: To investigate whether working memory capacity (WMC) modulates the effects of to-be-ignored speech on the memory of materials conveyed by to-be-attended speech. Method: Two tasks (reading span, Daneman & Carpenter, 1980; Ronnberg et al., 2008; and size-comparison span, Sorqvist, Ljungberg, & Ljung, 2010) were used to measure individual…

  6. Relationship between Measures of Working Memory Capacity and the Time Course of Short-Term Memory Retrieval and Interference Resolution

    ERIC Educational Resources Information Center

    Oztekin, Ilke; McElree, Brian

    2010-01-01

    The response-signal speed-accuracy trade-off (SAT) procedure was used to investigate the relationship between measures of working memory capacity and the time course of short-term item recognition. High- and low-span participants studied sequentially presented 6-item lists, immediately followed by a recognition probe. Analyses of composite list…

  7. Visual working memory capacity increases between ages 3 and 8 years, controlling for gains in attention, perception, and executive control.

    PubMed

    Pailian, Hrag; Libertus, Melissa E; Feigenson, Lisa; Halberda, Justin

    2016-08-01

    Research in adults has aimed to characterize constraints on the capacity of Visual Working Memory (VWM), in part because of the system's broader impacts throughout cognition. However, less is known about how VWM develops in childhood. Existing work has reached conflicting conclusions as to whether VWM storage capacity increases after infancy, and if so, when and by how much. One challenge is that previous studies did not control for developmental changes in attention and executive processing, which also may undergo improvement. We investigated the development of VWM storage capacity in children from 3 to 8 years of age, and in adults, while controlling for developmental change in exogenous and endogenous attention and executive control. Our results reveal that, when controlling for improvements in these abilities, VWM storage capacity increases across development and approaches adult-like levels between ages 6 and 8 years. More generally, this work highlights the value of estimating working memory, attention, perception, and decision-making components together. PMID:27225467

  8. Why Does Working Memory Capacity Predict Variation in Reading Comprehension? On the Influence of Mind Wandering and Executive Attention

    ERIC Educational Resources Information Center

    McVay, Jennifer C.; Kane, Michael J.

    2012-01-01

    Some people are better readers than others, and this variation in comprehension ability is predicted by measures of working memory capacity (WMC). The primary goal of this study was to investigate the mediating role of mind-wandering experiences in the association between WMC and normal individual differences in reading comprehension, as predicted…

  9. Mind Wandering and Reading Comprehension: Examining the Roles of Working Memory Capacity, Interest, Motivation, and Topic Experience

    ERIC Educational Resources Information Center

    Unsworth, Nash; McMillan, Brittany D.

    2013-01-01

    Individual differences in mind wandering and reading comprehension were examined in the current study. In particular, individual differences in mind wandering, working memory capacity, interest in the current topic, motivation to do well on the task, and topic experience and their relations with reading comprehension were examined in the current…

  10. Conducting the Train of Thought: Working Memory Capacity, Goal Neglect, and Mind Wandering in an Executive-Control Task

    ERIC Educational Resources Information Center

    McVay, Jennifer C.; Kane, Michael J.

    2009-01-01

    On the basis of the executive-attention theory of working memory capacity (WMC; e.g., M. J. Kane, A. R. A. Conway, D. Z. Hambrick, & R. W. Engle, 2007), the authors tested the relations among WMC, mind wandering, and goal neglect in a sustained attention to response task (SART; a go/no-go task). In 3 SART versions, making conceptual versus…

  11. "Something to Smile About": An Evaluation of a Capacity-Building Oral Health Intervention for Staff Working with Homeless People

    ERIC Educational Resources Information Center

    Coles, Emma; Watt, Celia; Freeman, Ruth

    2013-01-01

    Objective: To use a qualitative exploration to evaluate whether "Something to Smile About" (STSA), an oral health intervention, had increased the oral health capacity of staff working with homeless people. Setting: A National Health Service board area in Scotland. Method: A purposive sample of 14 staff members from STSA-participating organizations…

  12. Working Memory Capacity in a Go/No-Go Task: Age Differences in Interference, Processing Speed, and Attentional Control

    ERIC Educational Resources Information Center

    Rodríguez-Villagra, Odir Antonio; Göthe, Katrin; Oberauer, Klaus; Kliegl, Reinhold

    2013-01-01

    We tested the limits of working-memory capacity (WMC) of young adults, old adults, and children with a memory-updating task. The task consisted of mentally shifting spatial positions within a grid according to arrows, their color signaling either only go (control) or go/no-go conditions. The interference model (IM) of Oberauer and Kliegl (2006)…

  13. Working Memory Capacity and Its Relation to Stroop Interference and Facilitation Effects in Individuals with Mild Cognitive Impairment

    ERIC Educational Resources Information Center

    Sung, Jee Eun; Kim, Jin Hee; Jeong, Jee Hyang; Kang, Heejin

    2012-01-01

    Purpose: The purposes of the study were to investigate (a) the task-specific differences in short-term memory (STM) and working memory capacity (WMC) in individuals with mild cognitive impairment (MCI) and normal elderly adults (NEAs), (b) the Stroop interference and facilitation effects, and (c) the relationship of STM and WMC to the Stroop…

  14. Native American Women Leaders' Use of Information and Communication Technologies (ICTs) for Work-Life Balance (WLB) and Capacity Building

    ERIC Educational Resources Information Center

    Jensen, Crystal C.

    2013-01-01

    Native American women's leadership, information communication technologies (ICTs), work-life balance (WLB) and human capacity building (HCB) are grounded in social justice issues due to their long history of overall cultural decimation, inequitable access to technology, monetary resources, and social power (agency), and influence. Currently, there…

  15. Dynamic Relation Between Working Memory Capacity and Speech Recognition in Noise During the First 6 Months of Hearing Aid Use

    PubMed Central

    Classon, Elisabet; Larsby, Birgitta; Arlinger, Stig; Lunner, Thomas; Rudner, Mary; Rönnberg, Jerker

    2014-01-01

    The present study aimed to investigate the changing relationship between aided speech recognition and cognitive function during the first 6 months of hearing aid use. Twenty-seven first-time hearing aid users with symmetrical mild to moderate sensorineural hearing loss were recruited. Aided speech recognition thresholds in noise were obtained in the hearing aid fitting session as well as at 3 and 6 months postfitting. Cognitive abilities were assessed using a reading span test, which is a measure of working memory capacity, and a cognitive test battery. Results showed a significant correlation between reading span and speech reception threshold during the hearing aid fitting session. This relation was significantly weakened over the first 6 months of hearing aid use. Multiple regression analysis showed that reading span was the main predictor of speech recognition thresholds in noise when hearing aids were first fitted, but that the pure-tone average hearing threshold was the main predictor 6 months later. One way of explaining the results is that working memory capacity plays a more important role in speech recognition in noise initially rather than after 6 months of use. We propose that new hearing aid users engage working memory capacity to recognize unfamiliar processed speech signals because the phonological form of these signals cannot be automatically matched to phonological representations in long-term memory. As familiarization proceeds, the mismatch effect is alleviated, and the engagement of working memory capacity is reduced. PMID:25421088

  16. Working Memory Capacity: Attention Control, Secondary Memory, or Both? A Direct Test of the Dual-Component Model

    ERIC Educational Resources Information Center

    Unsworth, Nash; Spillers, Gregory J.

    2010-01-01

    The current study examined the extent to which attention control abilities, secondary memory abilities, or both accounted for variation in working memory capacity (WMC) and its relation to fluid intelligence. Participants performed various attention control, secondary memory, WMC, and fluid intelligence measures. Confirmatory factor analyses…

  17. The Relationship between Working Memory Capacity and L2 Oral Performance under Task-Based Careful Online Planning Condition

    ERIC Educational Resources Information Center

    Ahmadian, Mohammad Javad

    2012-01-01

    The study reported in this article aimed to investigate the way working memory capacity (WMC) interacts with careful online planning--a task-based implementation variable--to affect second language (L2) speech production. This issue is important to teachers, because it delves into one of the possible task-based implementation variables and thus…

  18. Working Memory Capacity and the Top-Down Control of Visual Search: Exploring the Boundaries of "Executive Attention"

    ERIC Educational Resources Information Center

    Kane, Michael J.; Poole, Bradley J.; Tuholski, Stephen W.; Engle, Randall W.

    2006-01-01

    The executive attention theory of working memory capacity (WMC) proposes that measures of WMC broadly predict higher order cognitive abilities because they tap important and general attention capabilities (R. W. Engle & M. J. Kane, 2004). Previous research demonstrated WMC-related differences in attention tasks that required restraint of habitual…

  19. The Contributions of Primary and Secondary Memory to Working Memory Capacity: An Individual Differences Analysis of Immediate Free Recall

    ERIC Educational Resources Information Center

    Unsworth, Nash; Spillers, Gregory J.; Brewer, Gene A.

    2010-01-01

    The present study tested the dual-component model of working memory capacity (WMC) by examining estimates of primary memory and secondary memory from an immediate free recall task. Participants completed multiple measures of WMC and general intellectual ability as well as multiple trials of an immediate free recall task. It was demonstrated that…

  20. Does Cognitive Strategy Training on Word Problems Compensate for Working Memory Capacity in Children with Math Difficulties?

    ERIC Educational Resources Information Center

    Swanson, H. Lee; Orosco, Michael J.; Lussier, Cathy

    2013-01-01

    Recent intervention studies directed to improve problem solving accuracy in children with math difficulties (MD) have found support for teaching cognitive strategies. This study addresses the question: What role does working memory capacity (WMC) play in strategy outcomes for children with MD? Four prediction models can be applied to strategy…

  1. Relative Effects of Explicit and Implicit Feedback: The Role of Working Memory Capacity and Language Analytic Ability

    ERIC Educational Resources Information Center

    Yilmaz, Yucel

    2013-01-01

    The purpose of this study is to investigate the role of two cognitive factors (i.e. working memory capacity [WMC] and language analytic ability [LAA]) in the extent to which L2 learners benefit from two different types of feedback (i.e. explicit correction and recasts). Forty-eight adult native speakers of English, who had no previous exposure to…

  2. Does Cognitive Strategy Training on Word Problems Compensate for Working Memory Capacity in Children with Math Difficulties?

    ERIC Educational Resources Information Center

    Swanson, H. Lee

    2014-01-01

    Cognitive strategies are important tools for children with math difficulties (MD) in learning to solve word problems. The effectiveness of strategy training, however, depends on working memory capacity (WMC). Thus, children with MD but with relatively higher WMC are more likely to benefit from strategy training, whereas children with lower WMC may…

  3. Loss of fibronectin from the aged stem cell niche affects the regenerative capacity of skeletal muscle in mice.

    PubMed

    Lukjanenko, Laura; Jung, M Juliane; Hegde, Nagabhooshan; Perruisseau-Carrier, Claire; Migliavacca, Eugenia; Rozo, Michelle; Karaz, Sonia; Jacot, Guillaume; Schmidt, Manuel; Li, Liangji; Metairon, Sylviane; Raymond, Frederic; Lee, Umji; Sizzano, Federico; Wilson, David H; Dumont, Nicolas A; Palini, Alessio; Fässler, Reinhard; Steiner, Pascal; Descombes, Patrick; Rudnicki, Michael A; Fan, Chen-Ming; von Maltzahn, Julia; Feige, Jerome N; Bentzinger, C Florian

    2016-08-01

    Age-related changes in the niche have long been postulated to impair the function of somatic stem cells. Here we demonstrate that the aged stem cell niche in skeletal muscle contains substantially reduced levels of fibronectin (FN), leading to detrimental consequences for the function and maintenance of muscle stem cells (MuSCs). Deletion of the gene encoding FN from young regenerating muscles replicates the aging phenotype and leads to a loss of MuSC numbers. By using an extracellular matrix (ECM) library screen and pathway profiling, we characterize FN as a preferred adhesion substrate for MuSCs and demonstrate that integrin-mediated signaling through focal adhesion kinase and the p38 mitogen-activated protein kinase pathway is strongly de-regulated in MuSCs from aged mice because of insufficient attachment to the niche. Reconstitution of FN levels in the aged niche remobilizes stem cells and restores youth-like muscle regeneration. Taken together, we identify the loss of stem cell adhesion to FN in the niche ECM as a previously unknown aging mechanism. PMID:27376579

  4. Measuring the mechanical efficiency of a working cardiac muscle sample at body temperature using a flow-through calorimeter.

    PubMed

    Taberner, Andrew J; Johnston, Callum M; Pham, Toan; June-Chiew Han; Ruddy, Bryan P; Loiselle, Denis S; Nielsen, Poul M F

    2015-08-01

    We have developed a new `work-loop calorimeter' that is capable of measuring, simultaneously, the work-done and heat production of isolated cardiac muscle samples at body temperature. Through the innovative use of thermoelectric modules as temperature sensors, the development of a low-noise fluid-flow system, and implementation of precise temperature control, the heat resolution of this device is 10 nW, an improvement by a factor of ten over previous designs. These advances have allowed us to conduct the first flow-through measurements of work output and heat dissipation from cardiac tissue at body temperature. The mechanical efficiency is found to vary with peak stress, and reaches a peak value of approximately 15 %, a figure similar to that observed in cardiac muscle at lower temperatures. PMID:26738140

  5. The muscle protein synthetic response to food ingestion.

    PubMed

    Gorissen, Stefan H M; Rémond, Didier; van Loon, Luc J C

    2015-11-01

    Preservation of skeletal muscle mass is of great importance for maintaining both metabolic health and functional capacity. Muscle mass maintenance is regulated by the balance between muscle protein breakdown and synthesis rates. Both muscle protein breakdown and synthesis rates have been shown to be highly responsive to physical activity and food intake. Food intake, and protein ingestion in particular, directly stimulates muscle protein synthesis rates. The postprandial muscle protein synthetic response to feeding is regulated on a number of levels, including dietary protein digestion and amino acid absorption, splanchnic amino acid retention, postprandial insulin release, skeletal muscle tissue perfusion, amino acid uptake by muscle, and intramyocellular signaling. The postprandial muscle protein synthetic response to feeding is blunted in many conditions characterized by skeletal muscle loss, such as aging and muscle disuse. Therefore, it is important to define food characteristics that modulate postprandial muscle protein synthesis. Previous work has shown that the muscle protein synthetic response to feeding can be modulated by changing the amount of protein ingested, the source of dietary protein, as well as the timing of protein consumption. Most of this work has studied the postprandial response to the ingestion of isolated protein sources. Only few studies have investigated the postprandial muscle protein synthetic response to the ingestion of protein dense foods, such as dairy and meat. The current review will focus on the capacity of proteins and protein dense food products to stimulate postprandial muscle protein synthesis and identifies food characteristics that may modulate the anabolic properties. PMID:26021783

  6. Keeping Up the Good Work: Developing and Sustaining Capacity for School Improvement.

    ERIC Educational Resources Information Center

    Herbert, Karen S.; Hatch, Thomas

    This paper describes findings from a study of school capacity, defined as the ability of schools to improve their practices and to sustain those improvements over time. Two schools in the San Francisco Bay Area (California) that have sustained success with distinct, though opposite, pedagogical approaches were examined to determine what makes a…

  7. Building Capacity for Oman's Online Teacher Training: Making an International Partnership Work

    ERIC Educational Resources Information Center

    Sales, Gregory C.; Al-Rahbi, Fathiya

    2008-01-01

    The Sultanate of Oman recently investigated the viability of online teacher training through a joint project funded by the U.S. Middle East Partnership Initiative and the Oman Ministry of Education. One aspect of the project was to build sufficient capacity within the Ministry to enable Oman to produce online training in the future. This article…

  8. The Developmental Influence of Primary Memory Capacity on Working Memory and Academic Achievement

    ERIC Educational Resources Information Center

    Hall, Debbora; Jarrold, Christopher; Towse, John N.; Zarandi, Amy L.

    2015-01-01

    In this study, we investigate the development of primary memory capacity among children. Children between the ages of 5 and 8 completed 3 novel tasks (split span, interleaved lists, and a modified free-recall task) that measured primary memory by estimating the number of items in the focus of attention that could be spontaneously recalled in…

  9. Nosotras viviremos. Las destrezas: A Capacity Building Training Manual for Working with Latina Farmworking Youth.

    ERIC Educational Resources Information Center

    Bolomey, Antonieta; Munoz-Lopez, Rosie; Ramirez-Garnica, Gabriela; Ramos, Flavia S.

    This project builds organizational and staff capacity to deliver HIV/AIDS education to farmworking Hispanic female adolescents and women. It includes two training manuals, one addressing the issues of farmworking mothers/mentors, and one addressing the issues of preadolescent and adolescent farmworking girls. This manual for girls emphasizes…

  10. Gesturing during mental problem solving reduces eye movements, especially for individuals with lower visual working memory capacity.

    PubMed

    Pouw, Wim T J L; Mavilidi, Myrto-Foteini; van Gog, Tamara; Paas, Fred

    2016-08-01

    Non-communicative hand gestures have been found to benefit problem-solving performance. These gestures seem to compensate for limited internal cognitive capacities, such as visual working memory capacity. Yet, it is not clear how gestures might perform this cognitive function. One hypothesis is that gesturing is a means to spatially index mental simulations, thereby reducing the need for visually projecting the mental simulation onto the visual presentation of the task. If that hypothesis is correct, less eye movements should be made when participants gesture during problem solving than when they do not gesture. We therefore used mobile eye tracking to investigate the effect of co-thought gesturing and visual working memory capacity on eye movements during mental solving of the Tower of Hanoi problem. Results revealed that gesturing indeed reduced the number of eye movements (lower saccade counts), especially for participants with a relatively lower visual working memory capacity. Subsequent problem-solving performance was not affected by having (not) gestured during the mental solving phase. The current findings suggest that our understanding of gestures in problem solving could be improved by taking into account eye movements during gesturing. PMID:26993293

  11. Anaerobic energy release in working muscle during 30 s to 3 min of exhausting bicycling.

    PubMed

    Medbø, J I; Tabata, I

    1993-10-01

    To examine the anaerobic energy release during intense exercise, 16 healthy young men cycled as long as possible at constant powers chosen to exhaust the subjects in approximately 30 s, 1 min, or 2-3 min. Muscle biopsies were taken before and approximately 10 s after exercise and analyzed for lactate, phosphocreatine (PCr), and other metabolites. O2 uptake was measured for determination of the accumulated O2 deficit (a whole body measure of the anaerobic energy release), and this indirect measure of the anaerobic energy release was compared with a direct value obtained from measured muscle metabolites. Muscle lactate concentration rose by 30.0 +/- 1.2 mmol/kg and muscle PCr concentration fell by 12.4 +/- 0.9 mmol/kg during the 2-3 min of exhausting exercise. The anaerobic ATP production was consequently 58 +/- 2 mmol/kg wet muscle mass, which may be the maximum anaerobic energy release for human muscle during bicycling. Because the anaerobic ATP production was 6 and 32% less for 1 min and 30 s of exercise, respectively, than for 2 min of exercise (P < 0.03), 2 min of exhausting exercise may be required for maximal use of anaerobic sources. Lactate production provided three times more ATP than PCr breakdown for all three exercise durations. There was a close linear relationship between the rates of anaerobic ATP production in muscle and the value estimated for the whole body by the O2 deficit (r = 0.94). This suggests that the accumulated O2 deficit is a valid measure of the anaerobic energy release during bicycling. PMID:8282617

  12. Maximal oxidative capacity during exercise is associated with skeletal muscle fuel selection and dynamic changes in mitochondrial protein acetylation

    PubMed Central

    Overmyer, Katherine A.; Evans, Charles R.; Qi, Nathan R.; Minogue, Catherine E.; Carson, Joshua J.; Chermside-Scabbo, Christopher J.; Koch, Lauren G.; Britton, Steven L.; Pagliarini, David J.; Coon, Joshua J.; Burant, Charles F.

    2015-01-01

    Summary Maximal exercise-associated oxidative capacity is strongly correlated with health and longevity in humans. Rats selectively bred for high running capacity (HCR) have improved metabolic health and are longer-lived than their low capacity counterparts (LCR). Using metabolomic and proteomic profiling, we show that HCR efficiently oxidize fatty acids (FA) and branched-chain amino acid (BCAA), sparing glycogen and reducing accumulation of short- and medium-chain acylcarnitines. HCR mitochondria have reduced acetylation of mitochondrial proteins within oxidative pathways at rest, and there is rapid protein deacetylation with exercise, which is greater in HCR than LCR. Fluxomic analysis of valine degradation with exercise demonstrates a functional role of differential protein acetylation in HCR and LCR. Our data suggest efficient FA and BCAA utilization contribute to high intrinsic exercise capacity and the health and longevity benefits associated with enhanced fitness. PMID:25738461

  13. Investigating shoulder muscle loading and exerted forces during wall painting tasks: influence of gender, work height and paint tool design.

    PubMed

    Rosati, Patricia M; Chopp, Jaclyn N; Dickerson, Clark R

    2014-07-01

    The task of wall painting produces considerable risk to the workers, both male and female, primarily in the development of upper extremity musculoskeletal disorders. Insufficient information is currently available regarding the potential benefits of using different paint roller designs or the possible adverse effects of painting at different work heights. The aim of this study was to investigate the influence of gender, work height, and paint tool design on shoulder muscle activity and exerted forces during wall painting. Ten young adults, five male and five female, were recruited to perform simulated wall painting at three different work heights with three different paint roller designs while upper extremity muscle activity and horizontal push force were recorded. Results demonstrated that for female participants, significantly greater total average (p = 0.007) and integrated (p = 0.047) muscle activity was present while using the conventional and curly flex paint roller designs compared to the proposed design in which the load was distributed between both hands. Additionally, for both genders, the high working height imposed greater muscular demands compared to middle and low heights. These findings suggest that, if possible, avoid painting at extreme heights (low or high) and that for female painters, consider a roller that requires the use of two hands; this will reduce fatigue onset and subsequently mitigate potential musculoskeletal shoulder injury risks. PMID:24636728

  14. Multi-Programmatic and Institutional Computing Capacity Resource Attachment 2 Statement of Work

    SciTech Connect

    Seager, M

    2002-04-15

    Lawrence Livermore National Laboratory (LLNL) has identified high-performance computing as a critical competency necessary to meet the goals of LLNL's scientific and engineering programs. Leadership in scientific computing demands the availability of a stable, powerful, well-balanced computational infrastructure, and it requires research directed at advanced architectures, enabling numerical methods and computer science. To encourage all programs to benefit from the huge investment being made by the Advanced Simulation and Computing Program (ASCI) at LLNL, and to provide a mechanism to facilitate multi-programmatic leveraging of resources and access to high-performance equipment by researchers, M&IC was created. The Livermore Computing (LC) Center, a part of the Computations Directorate Integrated Computing and Communications (ICC) Department can be viewed as composed of two facilities, one open and one secure. This acquisition is focused on the M&IC resources in the Open Computing Facility (OCF). For the M&IC program, recent efforts and expenditures have focused on enhancing capacity and stabilizing the TeraCluster 2000 (TC2K) resource. Capacity is a measure of the ability to process a varied workload from many scientists simultaneously. Capability represents the ability to deliver a very large system to run scientific calculations at large scale. In this procurement action, we intend to significantly increase the capability of the M&IC resource to address multiple teraFLOP/s problems, and well as increasing the capacity to do many 100 gigaFLOP/s calculations.

  15. The Developmental Influence of Primary Memory Capacity on Working Memory and Academic Achievement

    PubMed Central

    2015-01-01

    In this study, we investigate the development of primary memory capacity among children. Children between the ages of 5 and 8 completed 3 novel tasks (split span, interleaved lists, and a modified free-recall task) that measured primary memory by estimating the number of items in the focus of attention that could be spontaneously recalled in serial order. These tasks were calibrated against traditional measures of simple and complex span. Clear age-related changes in these primary memory estimates were observed. There were marked individual differences in primary memory capacity, but each novel measure was predictive of simple span performance. Among older children, each measure shared variance with reading and mathematics performance, whereas for younger children, the interleaved lists task was the strongest single predictor of academic ability. We argue that these novel tasks have considerable potential for the measurement of primary memory capacity and provide new, complementary ways of measuring the transient memory processes that predict academic performance. The interleaved lists task also shared features with interference control tasks, and our findings suggest that young children have a particular difficulty in resisting distraction and that variance in the ability to resist distraction is also shared with measures of educational attainment. PMID:26075630

  16. The developmental influence of primary memory capacity on working memory and academic achievement.

    PubMed

    Hall, Debbora; Jarrold, Christopher; Towse, John N; Zarandi, Amy L

    2015-08-01

    In this study, we investigate the development of primary memory capacity among children. Children between the ages of 5 and 8 completed 3 novel tasks (split span, interleaved lists, and a modified free-recall task) that measured primary memory by estimating the number of items in the focus of attention that could be spontaneously recalled in serial order. These tasks were calibrated against traditional measures of simple and complex span. Clear age-related changes in these primary memory estimates were observed. There were marked individual differences in primary memory capacity, but each novel measure was predictive of simple span performance. Among older children, each measure shared variance with reading and mathematics performance, whereas for younger children, the interleaved lists task was the strongest single predictor of academic ability. We argue that these novel tasks have considerable potential for the measurement of primary memory capacity and provide new, complementary ways of measuring the transient memory processes that predict academic performance. The interleaved lists task also shared features with interference control tasks, and our findings suggest that young children have a particular difficulty in resisting distraction and that variance in the ability to resist distraction is also shared with measures of educational attainment. PMID:26075630

  17. Developing Future Health Professionals' Capacities for Working with Aboriginal and Torres Strait Islander Peoples

    ERIC Educational Resources Information Center

    Hendrick, Antonia; Britton, Katherine Frances; Hoffman, Julie; Kickett, Marion

    2014-01-01

    This article details reflections of an interdisciplinary team of educators working with groups of health sciences students in preparing them for working with Aboriginal and Torres Strait Islander peoples. The first-year common core unit discussed here is one attempt to equip future health practitioners with skills and knowledges to work adequately…

  18. Influence of Amino Acid Compositions and Peptide Profiles on Antioxidant Capacities of Two Protein Hydrolysates from Skipjack Tuna (Katsuwonus pelamis) Dark Muscle.

    PubMed

    Chi, Chang-Feng; Hu, Fa-Yuan; Wang, Bin; Li, Zhong-Rui; Luo, Hong-Yu

    2015-05-01

    Influence of amino acid compositions and peptide profiles on antioxidant capacities of two protein hydrolysates from skipjack tuna (Katsuwonus pelamis) dark muscle was investigated. Dark muscles from skipjack tuna were hydrolyzed using five separate proteases, including pepsin, trypsin, Neutrase, papain and Alcalase. Two hydrolysates, ATH and NTH, prepared using Alcalase and Neutrase, respectively, showed the strongest antioxidant capacities and were further fractionated using ultrafiltration and gel filtration chromatography. Two fractions, Fr.A3 and Fr.B2, isolated from ATH and NTH, respectively, showed strong radical scavenging activities toward 2,2-diphenyl-1-picrylhydrazyl radicals (EC50 1.08% ± 0.08% and 0.98% ± 0.07%), hydroxyl radicals (EC50 0.22% ± 0.03% and 0.48% ± 0.05%), and superoxide anion radicals (EC50 1.31% ± 0.11% and 1.56% ± 1.03%) and effectively inhibited lipid peroxidation. Eighteen peptides from Fr.A3 and 13 peptides from Fr.B2 were isolated by reversed-phase high performance liquid chromatography, and their amino acid sequences were determined. The elevated antioxidant activity of Fr.A3 might be due to its high content of hydrophobic and aromatic amino acid residues (181.1 and 469.9 residues/1000 residues, respectively), small molecular sizes (3-6 peptides), low molecular weights (524.78 kDa), and amino acid sequences (antioxidant score 6.11). This study confirmed that a smaller molecular size, the presence of hydrophobic and aromatic amino acid residues, and the amino acid sequences were the key factors that determined the antioxidant activities of the proteins, hydrolysates and peptides. The results also demonstrated that the derived hydrolysates and fractions from skipjack tuna (K. pelamis) dark muscles could prevent oxidative reactions and might be useful for food preservation and medicinal purposes. PMID:25923316

  19. Manipulating training intensity and volume in already well-trained rats: effect on skeletal muscle oxidative and glycolytic enzymes and buffering capacity.

    PubMed

    Laursen, Paul B; Marsh, Susan A; Jenkins, David G; Coombes, Jeff S

    2007-06-01

    Well-trained endurance athletes undergo periods of high-intensity interval training (HIT) or high-volume training (HVT) to improve exercise performance, but little is known about the mechanistic changes that occur during this time. The purpose of this study was to examine the influence of HIT and HVT on the activities of citrate synthase (CS) and phosphofructokinase (PFK), and on intramuscular buffering capacity (betam) in already well-trained rats. At 4 weeks of age, Wistar rats were divided into sedentary (SED; n=18) and exercise training groups (n=38). Following a 10 week preliminary training program, trained rats were divided randomly into 3 further groups that completed 4 additional weeks of continued endurance (CON, n=14), high-intensity training (HIT, n=12), or high-volume training (HVT, n=12). Soleus (SOL), red and white gastrocnemius (RG and WG), and red and white vastus (RV and WV) muscles were removed 24-48 h after a final run-to-fatigue performance test (30 m.min(-1) 25% grade) to determine the activities of CS, PFK, and betam. No differences in run time to exhaustion were found between the groups. However the HIT group possessed CS and PFK activities and betam in WV muscle that were 60%, 24%, and 10% higher, respectively (all p<0.05), compared with the HVT group; differences were not found between the HIT and CON groups. Although no differences in run performance were found, HIT compared with HVT in already well-trained rats resulted in significantly higher oxidative and glycolytic capacities of fast-contracting fibres. No differences were shown in fast-contracting muscle between HIT and CON. PMID:17510678

  20. Influence of Amino Acid Compositions and Peptide Profiles on Antioxidant Capacities of Two Protein Hydrolysates from Skipjack Tuna (Katsuwonus pelamis) Dark Muscle

    PubMed Central

    Chi, Chang-Feng; Hu, Fa-Yuan; Wang, Bin; Li, Zhong-Rui; Luo, Hong-Yu

    2015-01-01

    Influence of amino acid compositions and peptide profiles on antioxidant capacities of two protein hydrolysates from skipjack tuna (Katsuwonus pelamis) dark muscle was investigated. Dark muscles from skipjack tuna were hydrolyzed using five separate proteases, including pepsin, trypsin, Neutrase, papain and Alcalase. Two hydrolysates, ATH and NTH, prepared using Alcalase and Neutrase, respectively, showed the strongest antioxidant capacities and were further fractionated using ultrafiltration and gel filtration chromatography. Two fractions, Fr.A3 and Fr.B2, isolated from ATH and NTH, respectively, showed strong radical scavenging activities toward 2,2-diphenyl-1-picrylhydrazyl radicals (EC50 1.08% ± 0.08% and 0.98% ± 0.07%), hydroxyl radicals (EC50 0.22% ± 0.03% and 0.48% ± 0.05%), and superoxide anion radicals (EC50 1.31% ± 0.11% and 1.56% ± 1.03%) and effectively inhibited lipid peroxidation. Eighteen peptides from Fr.A3 and 13 peptides from Fr.B2 were isolated by reversed-phase high performance liquid chromatography, and their amino acid sequences were determined. The elevated antioxidant activity of Fr.A3 might be due to its high content of hydrophobic and aromatic amino acid residues (181.1 and 469.9 residues/1000 residues, respectively), small molecular sizes (3–6 peptides), low molecular weights (524.78 kDa), and amino acid sequences (antioxidant score 6.11). This study confirmed that a smaller molecular size, the presence of hydrophobic and aromatic amino acid residues, and the amino acid sequences were the key factors that determined the antioxidant activities of the proteins, hydrolysates and peptides. The results also demonstrated that the derived hydrolysates and fractions from skipjack tuna (K. pelamis) dark muscles could prevent oxidative reactions and might be useful for food preservation and medicinal purposes. PMID:25923316

  1. Effects of Combined Aerobic and Resistance Exercise on Exercise Capacity, Muscle Strength and Quality of Life in HIV-Infected Patients: A Systematic Review and Meta-Analysis

    PubMed Central

    Gomes Neto, Mansueto; Conceição, Cristiano Sena; Carvalho, Vitor Oliveira; Brites, Carlos

    2015-01-01

    Background Many HIV-infected patients demonstrate disability and lower aerobic capacity. The inclusion of resistance training combined with aerobic exercise in a single program is known as combined aerobic and resistance exercise (CARE) and seems to be an effective strategy to improve muscle weakness, as well as aerobic capacity in HIV-infected patients. We performed a meta-analysis to investigate the effects of CARE in HIV-infected patients. Methods We searched MEDLINE, Cochrane Controlled Trials Register, EMBASE, CINAHL (from the earliest date available to august 2014) for controlled trials that evaluated the effects of CARE in HIV-infected patients. Weighted mean differences (WMD) and 95% confidence intervals (CIs) were calculated, and heterogeneity was assessed using the I2 test. Results Seven studies met the study criteria. CARE resulted in improvement in Peak VO2 WMD (4.48 mL·kg-1·min-1 95% CI: 2.95 to 6.0), muscle strength of the knee extensors WMD (25.06 Kg 95% CI: 10.46 to 39.66) and elbow flexors WMD (4.44 Kg 95% CI: 1.22 to 7.67) compared with no exercise group. The meta-analyses also showed significant improvement in Health status, Energy/Vitality and physical function domains of quality of life for participants in the CARE group compared with no exercise group. A nonsignificant improvement in social function domain of quality of life was found for participants in the CARE group compared with no exercise group. Conclusions Combined aerobic and resistance exercise may improve peak VO2, muscle strength and health status, energy and physical function domains of quality of life and should be considered as a component of care of HIV-infected individuals. PMID:26378794

  2. Work improvement factors for the amelioration of work ability, with a focus on individual capacity to deal with stress in an IT company.

    PubMed

    Ohta, Masanori; Higuchi, Yoshiyuki; Kumashiro, Masaharu; Yamato, Hiroshi; Sugimura, Hisamichi

    2015-03-01

    The aim of this study was to explore factors that ameliorate work ability by focusing on workers' capacity to deal with stress.The subjects were 1,330 workers from the Japanese information technology (IT) sector. Each subject completed questionnaires in 2011 and 2012 that consisted of the work ability index (WAI), the three-item sense of coherence (SOC), and the Mental Health Improvement and Reinforcement Research of Recognition (MIRROR). The results of the WAI were also obtained in 2013. The median SOC score in 2011 was used to divide the subjects into two groups, the Low SOC group and the High SOC group, then we verified the factors that contributed to improved work ability in both of these groups over a two-year period. Results indicate that an improvement in work ability in the Low SOC group could be predicted by giving workers opportunities for education or training, by making efforts to reduce the stress of commuting, by clarifying their assignments, and by establishing support systems when troubles occur. For the High SOC group, such improvements could be predicted by giving workers job control, by giving education or training for the promotion of their abilities, and by establishing a system for assuming responsibility. In conclusion, improvements in the work environment can increase the work ability of Japanese IT workers in conformity with their capacity to deal with stress. PMID:25787099

  3. The effects of a passive exoskeleton on muscle activity, discomfort and endurance time in forward bending work.

    PubMed

    Bosch, Tim; van Eck, Jennifer; Knitel, Karlijn; de Looze, Michiel

    2016-05-01

    Exoskeletons may form a new strategy to reduce the risk of developing low back pain in stressful jobs. In the present study we examined the potential of a so-called passive exoskeleton on muscle activity, discomfort and endurance time in prolonged forward-bended working postures. Eighteen subjects performed two tasks: a simulated assembly task with the trunk in a forward-bended position and static holding of the same trunk position without further activity. We measured the electromyography for muscles in the back, abdomen and legs. We also measured the perceived local discomfort. In the static holding task we determined the endurance, defined as the time that people could continue without passing a specified discomfort threshold. In the assembly task we found lower muscle activity (by 35-38%) and lower discomfort in the low back when wearing the exoskeleton. Additionally, the hip extensor activity was reduced. The exoskeleton led to more discomfort in the chest region. In the task of static holding, we observed that exoskeleton use led to an increase in endurance time from 3.2 to 9.7 min, on average. The results illustrate the good potential of this passive exoskeleton to reduce the internal muscle forces and (reactive) spinal forces in the lumbar region. However, the adoption of an over-extended knee position might be, among others, one of the concerns when using the exoskeleton. PMID:26851481

  4. [Muscular mechanisms of lowering of physical working capacity in chronic heart failure and action of beta-adrenoblockers].

    PubMed

    Syrkin, A L; Poltavskaia, M G; Molchanova, I V; Churganova, L Iu; Chaplygin, A V

    2005-01-01

    Parameters of physical working capacity (symptom limited treadmill test with gas analysis, 6 min walk test and usual everyday activity), activity of muscular metaboreflex, efficacy of pulmonary ventilation, and heart rate variability were studied in 50 patients with postinfarction cardiosclerosis with chronic class I-III heart failure and 30 patients without heart failure. Patients with heart failure of all functional classes had lowered parameters of working capacity while metaboloreflex hyperactivation and diminished effectiveness of ventilation were found only in patients with clinical signs of chronic heart failure but not in those with symptomless left ventricular dysfunction. Therapy with metoprolol was associated with lowering of activity of metaboloreflex, augmented effectiveness of ventilation and heart rate variability, improvement of results of 6 min test and everyday activity without considerable changes of peak oxygen consumption. PMID:16234766

  5. High-altitude ancestry and hypoxia acclimation have distinct effects on exercise capacity and muscle phenotype in deer mice.

    PubMed

    Lui, Mikaela A; Mahalingam, Sajeni; Patel, Paras; Connaty, Alex D; Ivy, Catherine M; Cheviron, Zachary A; Storz, Jay F; McClelland, Grant B; Scott, Graham R

    2015-05-01

    The hypoxic and cold environment at high altitudes requires that small mammals sustain high rates of O2 transport for exercise and thermogenesis while facing a diminished O2 availability. We used laboratory-born and -raised deer mice (Peromyscus maniculatus) from highland and lowland populations to determine the interactive effects of ancestry and hypoxia acclimation on exercise performance. Maximal O₂consumption (V̇o(2max)) during exercise in hypoxia increased after hypoxia acclimation (equivalent to the hypoxia at ∼4,300 m elevation for 6-8 wk) and was consistently greater in highlanders than in lowlanders. V̇o(2max) during exercise in normoxia was not affected by ancestry or acclimation. Highlanders also had consistently greater capillarity, oxidative fiber density, and maximal activities of oxidative enzymes (cytochrome c oxidase and citrate synthase) in the gastrocnemius muscle, lower lactate dehydrogenase activity in the gastrocnemius, and greater cytochrome c oxidase activity in the diaphragm. Hypoxia acclimation did not affect any of these muscle traits. The unique gastrocnemius phenotype of highlanders was associated with higher mRNA and protein abundances of peroxisome proliferator-activated receptor γ (PPARγ). Vascular endothelial growth factor (VEGFA) transcript abundance was lower in highlanders, and hypoxia acclimation reduced the expression of numerous genes that regulate angiogenesis and energy metabolism, in contrast to the observed population differences in muscle phenotype. Lowlanders exhibited greater increases in blood hemoglobin content, hematocrit, and wet lung mass (but not dry lung mass) than highlanders after hypoxia acclimation. Genotypic adaptation to high altitude, therefore, improves exercise performance in hypoxia by mechanisms that are at least partially distinct from those underlying hypoxia acclimation. PMID:25695288

  6. High-altitude ancestry and hypoxia acclimation have distinct effects on exercise capacity and muscle phenotype in deer mice

    PubMed Central

    Lui, Mikaela A.; Mahalingam, Sajeni; Patel, Paras; Connaty, Alex D.; Ivy, Catherine M.; Cheviron, Zachary A.; Storz, Jay F.; McClelland, Grant B.

    2015-01-01

    The hypoxic and cold environment at high altitudes requires that small mammals sustain high rates of O2 transport for exercise and thermogenesis while facing a diminished O2 availability. We used laboratory-born and -raised deer mice (Peromyscus maniculatus) from highland and lowland populations to determine the interactive effects of ancestry and hypoxia acclimation on exercise performance. Maximal O2 consumption (V̇o2max) during exercise in hypoxia increased after hypoxia acclimation (equivalent to the hypoxia at ∼4,300 m elevation for 6–8 wk) and was consistently greater in highlanders than in lowlanders. V̇o2max during exercise in normoxia was not affected by ancestry or acclimation. Highlanders also had consistently greater capillarity, oxidative fiber density, and maximal activities of oxidative enzymes (cytochrome c oxidase and citrate synthase) in the gastrocnemius muscle, lower lactate dehydrogenase activity in the gastrocnemius, and greater cytochrome c oxidase activity in the diaphragm. Hypoxia acclimation did not affect any of these muscle traits. The unique gastrocnemius phenotype of highlanders was associated with higher mRNA and protein abundances of peroxisome proliferator-activated receptor γ (PPARγ). Vascular endothelial growth factor (VEGFA) transcript abundance was lower in highlanders, and hypoxia acclimation reduced the expression of numerous genes that regulate angiogenesis and energy metabolism, in contrast to the observed population differences in muscle phenotype. Lowlanders exhibited greater increases in blood hemoglobin content, hematocrit, and wet lung mass (but not dry lung mass) than highlanders after hypoxia acclimation. Genotypic adaptation to high altitude, therefore, improves exercise performance in hypoxia by mechanisms that are at least partially distinct from those underlying hypoxia acclimation. PMID:25695288

  7. Thirst and work capacity of older people in a hot environment.

    PubMed

    Marszalek, A

    2000-01-01

    In a hot environment, especially during exercise, the main role of thermoregulative mechanisms is to dissipate excessive heat from the body. The most effective way of heat dissipation is sweat production and its evaporation off skin surface. Intense sweating results in a considerable loss of water and electrolytes. There are some results that indicate lower thirst of older men than young ones in response to a hot environment and osmotic stimuli. Our studies conducted in men of different ages exposed to a hot environment indicated that there were no significant differences in rectal temperature (Tre) or heat storage (S) among groups at rest. Lower Tre and lower S in older men with higher physical capacity for their age than in young ones with average physical capacity was shown. However, in all the experiments significantly lower thirst in older men than in the young was indicated. Special attention should be paid to fluid replacement among workers in a hot environment because of lower thirst and lower hydration of older men. These individuals may be exposed to dehydration risk during prolonged exercise, despite the possibility to tolerate heat strain as well as young ones. Further studies are necessary because of some diversity in the meaning of the results. PMID:10828160

  8. Children's Use of Semantic Organizational Strategies Is Mediated by Working Memory Capacity

    ERIC Educational Resources Information Center

    Schleepen, Tamara M. J.; Jonkman, Lisa M.

    2012-01-01

    In adults, the ability to apply semantic grouping strategies has been found to depend on working memory. To investigate this relation in children, two sort-recall tasks (one without and one with a grouping instruction) were administered to 6-12-year-olds. The role of working memory was examined by means of mediation analyses and by assessing…

  9. Age Differences in Visual Working Memory Capacity: Not Based on Encoding Limitations

    ERIC Educational Resources Information Center

    Cowan, Nelson; AuBuchon, Angela M.; Gilchrist, Amanda L.; Ricker, Timothy J.; Saults, J. Scott

    2011-01-01

    Why does visual working memory performance increase with age in childhood? One recent study (Cowan et al., 2010b) ruled out the possibility that the basic cause is a tendency in young children to clutter working memory with less-relevant items (within a concurrent array, colored items presented in one of two shapes). The age differences in memory…

  10. Red blood cells do not contribute to removal of K+ released from exhaustively working forearm muscle.

    PubMed

    Maassen, N; Foerster, M; Mairbäurl, H

    1998-07-01

    K+ released from exercising muscle via K+ channels needs to be removed from the interstitium into the blood to maintain high muscle cell membrane potential and allow normal muscle contractility. Uptake by red blood cells has been discussed as one mechanism that would also serve to regulate red blood cell volume, which was found to be constant despite increased plasma osmolality and K+ concentration ([K+pl]). We evaluated exercise-related changes in [K+pl], pH, osmolality, mean cellular Hb concentration, cell water, and red blood cell K+ concentration during exhaustive handgrip exercise. Unidirectional 86Rb+ (K+) uptake by red blood cells was measured in media with elevated extracellular K+, osmolarity, and catecholamines to simulate particularly those exercise-related changes in plasma composition that are known to stimulate K+ uptake. During exercise [K+pl] increased from 4.4 +/- 0.7 to 7.1 +/- 0.5 mmol/l plasma water and red blood cell K+ concentration increased from 137.2 +/- 6.0 to 144.6 +/- 4.6 mmol/l cell water (P muscle despite the elevated [K+pl]. The tendency for an increase in intracellular K+ concentration was due to a slight, although statistically not significant, decrease in red blood cell volume. K+ uptake, although elevated, was too small to move significant amounts of K+ into red blood cells. Our results suggest that red blood cells do not contribute to the removal of K+ released from muscle and do not regulate their volume by K+ uptake during exhaustive forearm exercise. PMID:9655793

  11. Individual differences in working memory capacity are reflected in different ERP and EEG patterns to task difficulty.

    PubMed

    Dong, Shanshan; Reder, Lynne M; Yao, Yuan; Liu, Yuqiu; Chen, Feiyan

    2015-08-01

    This study examined whether there are neural markers of individual differences in working memory (WM) capacity and whether these differences are only manifest when performing a demanding WM task or at all levels of difficulty. Each subject's WM capacity was estimated using a modified digit span task prior to participation in an N-back task that varied difficulty from 1- to 4-back. While performing the N-back task, subjects wore scalp electrodes that allowed measurement of both event-related potentials (ERP) and event-related synchronization and desynchronization (ERS/ERD). Those subjects classified as low WM were more affected by the higher cognitive demands (many more errors in the 4-back task and generally slower responses) than those classified as high WM. These behavioral differences between the two groups were also apparent in the neural markers. Specifically, low WM subjects, when compared with high WM subjects, produced smaller P300 amplitudes and theta ERS, as well as greater alpha ERD at the most difficult level. Importantly, the observed differences in electrophysiological responses between the two groups were also observed at the lowest difficulty level, not just when the task challenged WM capacity. In addition, P300 amplitudes and alpha ERD responses were found to correlate with individual WM capacities independent of the task difficulty. These results suggest that there are qualitative neural differences among individuals with different WM capacities when approaching cognitive operations. Individuals with high WM capacities may make more efficient use of neural resources to keep their attention focused on the task-relevant information when performing cognitive tasks. PMID:25976774

  12. Effect of tighter glycemic control on cardiac function, exercise capacity, and muscle strength in heart failure patients with type 2 diabetes: a randomized study

    PubMed Central

    Nielsen, Roni; Wiggers, Henrik; Thomsen, Henrik Holm; Bovin, Ann; Refsgaard, Jens; Abrahamsen, Jan; Møller, Niels; Bøtker, Hans Erik; Nørrelund, Helene

    2016-01-01

    Objectives In patients with type 2 diabetes (T2D) and heart failure (HF), the optimal glycemic target is uncertain, and evidence-based data are lacking. Therefore, we performed a randomized study on the effect of optimized glycemic control on left ventricular function, exercise capacity, muscle strength, and body composition. Design and methods 40 patients with T2D and HF (left ventricular ejection fraction (LVEF) 35±12% and hemoglobin A1c (HbA1c) 8.4±0.7% (68±0.8 mmol/mol)) were randomized to either 4-month optimization (OPT group) or non-optimization (non-OPT group) of glycemic control. Patients underwent dobutamine stress echocardiography, cardiopulmonary exercise test, 6 min hall-walk test (6-MWT), muscle strength examination, and dual X-ray absorptiometry scanning at baseline and at follow-up. Results 39 patients completed the study. HbA1c decreased in the OPT versus the non-OPT group (8.4±0.8% (68±9 mmol/mol) to 7.6±0.7% (60±7 mmol/mol) vs 8.3±0.7% (67±10 mmol/mol) to 8.4±1.0% (68±11 mmol/mol); p<0.001). There was no difference between the groups with respect to changes in myocardial contractile reserve (LVEF (p=0.18)), oxygen consumption (p=0.55), exercise capacity (p=0.12), and 6-MWT (p=0.84). Muscle strength decreased in the non-OPT compared with the OPT group (37.2±8.1 to 34.8±8.3 kg vs 34.9±10.2 to 35.4±10.7 kg; p=0.01), in line with a non-significant decrease in lean (p=0.07) and fat (p=0.07) tissue mass in the non-OPT group. Hypoglycemia and fluid retention did not differ between groups. Conclusions 4 months of optimization of glycemic control was associated with preserved muscle strength and lean body mass in patients with T2D and HF compared with lenient control, and had no deleterious effect on left ventricular contractile function and seemed to be safe. Trial registration number NCT01213784; pre-results. PMID:27158520

  13. Beneficial Effects of Physical Exercise on Functional Capacity and Skeletal Muscle Oxidative Stress in Rats with Aortic Stenosis-Induced Heart Failure

    PubMed Central

    Gomes, Mariana Janini; Martinez, Paula Felippe; Campos, Dijon Henrique Salomé; Pagan, Luana Urbano; Bonomo, Camila; Lima, Aline Regina Ruiz; Damatto, Ricardo Luiz; Cezar, Marcelo D. M.; Damatto, Felipe Cezar; Rosa, Camila Moreno; Garcia, Camila Marchiolli; Reyes, David Rafael Abreu; Fernandes, Ana Angélica Henrique; Fernandes, Denise Castro; Laurindo, Francisco Rafael; Okoshi, Katashi; Okoshi, Marina Politi

    2016-01-01

    Objective. We evaluated the influence of exercise on functional capacity, cardiac remodeling, and skeletal muscle oxidative stress, MAPK, and NF-κB pathway in rats with aortic stenosis- (AS-) induced heart failure (HF). Methods and Results. Eighteen weeks after AS induction, rats were assigned into sedentary control (C-Sed), exercised control (C-Ex), sedentary AS (AS-Sed), and exercised AS (AS-Ex) groups. Exercise was performed on treadmill for eight weeks. Statistical analyses were performed with Goodman and ANOVA or Mann-Whitney. HF features frequency and mortality did not differ between AS groups. Exercise improved functional capacity, assessed by maximal exercise test on treadmill, without changing echocardiographic parameters. Soleus cross-sectional areas did not differ between groups. Lipid hydroperoxide concentration was higher in AS-Sed than C-Sed and AS-Ex. Activity of antioxidant enzymes superoxide dismutase and glutathione peroxidase was changed in AS-Sed and restored in AS-Ex. NADPH oxidase activity and gene expression of its subunits did not differ between AS groups. Total ROS generation was lower in AS-Ex than C-Ex. Exercise modulated MAPK in AS-Ex and did not change NF-κB pathway proteins. Conclusion. Exercise improves functional capacity in rats with AS-induced HF regardless of echocardiographic parameter changes. In soleus, exercise reduces oxidative stress, preserves antioxidant enzyme activity, and modulates MAPK expression. PMID:26904168

  14. Beneficial Effects of Physical Exercise on Functional Capacity and Skeletal Muscle Oxidative Stress in Rats with Aortic Stenosis-Induced Heart Failure.

    PubMed

    Gomes, Mariana Janini; Martinez, Paula Felippe; Campos, Dijon Henrique Salomé; Pagan, Luana Urbano; Bonomo, Camila; Lima, Aline Regina Ruiz; Damatto, Ricardo Luiz; Cezar, Marcelo D M; Damatto, Felipe Cezar; Rosa, Camila Moreno; Garcia, Camila Marchiolli; Reyes, David Rafael Abreu; Fernandes, Ana Angélica Henrique; Fernandes, Denise Castro; Laurindo, Francisco Rafael; Okoshi, Katashi; Okoshi, Marina Politi

    2016-01-01

    Objective. We evaluated the influence of exercise on functional capacity, cardiac remodeling, and skeletal muscle oxidative stress, MAPK, and NF-κB pathway in rats with aortic stenosis- (AS-) induced heart failure (HF). Methods and Results. Eighteen weeks after AS induction, rats were assigned into sedentary control (C-Sed), exercised control (C-Ex), sedentary AS (AS-Sed), and exercised AS (AS-Ex) groups. Exercise was performed on treadmill for eight weeks. Statistical analyses were performed with Goodman and ANOVA or Mann-Whitney. HF features frequency and mortality did not differ between AS groups. Exercise improved functional capacity, assessed by maximal exercise test on treadmill, without changing echocardiographic parameters. Soleus cross-sectional areas did not differ between groups. Lipid hydroperoxide concentration was higher in AS-Sed than C-Sed and AS-Ex. Activity of antioxidant enzymes superoxide dismutase and glutathione peroxidase was changed in AS-Sed and restored in AS-Ex. NADPH oxidase activity and gene expression of its subunits did not differ between AS groups. Total ROS generation was lower in AS-Ex than C-Ex. Exercise modulated MAPK in AS-Ex and did not change NF-κB pathway proteins. Conclusion. Exercise improves functional capacity in rats with AS-induced HF regardless of echocardiographic parameter changes. In soleus, exercise reduces oxidative stress, preserves antioxidant enzyme activity, and modulates MAPK expression. PMID:26904168

  15. Does living and working in a hot environment induce clinically relevant changes in immune function and voluntary force production capacity?

    PubMed

    Knez, Wade; Girard, Olivier; Racinais, Sebastien; Walsh, Andrew; Gaoua, Nadia; Grantham, Justin

    2014-01-01

    This study investigated the effect of living (summer vs. winter) and working (morning vs. afternoon) in a hot environment on markers of immune function and forearm strength. Thirty-one healthy male gas field employees were screened before (between 05:30 and 07:00) and after their working day (between 15:30 and 17:00) during both seasons. Body core temperature and physical activity were recorded throughout the working days. The hot condition (i.e. summer) led a higher (p≤0.05) average body core temperature (~37.2 vs. ~37.4 °C) but reduced physical activity (-14.8%) during the work-shift. Our data showed an increase (p≤0.05) in lymphocyte and monocyte counts in the summer. Additionally, work-shift resulted in significant (p≤0.001) changes in leukocytes, lymphocytes and monocytes independently of the environment. Handgrip (p=0.069) and pinch (p=0.077) forces tended to be reduced from pre-to post-work, while only force produced during handgrip manoeuvres was significantly reduced (p≤0.05) during the hot compared to the temperate season. No interactions were observed between the environment and work-shift for any marker of immune function or forearm strength. In summary, working and living in hot conditions impact on markers of immune function and work capacity; however by self-regulating energy expenditure, immune markers remained in a healthy reference range. PMID:24583514

  16. Working memory capacity and overgeneral autobiographical memory in young and older adults.

    PubMed

    Ros, Laura; Latorre, José Miguel; Serrano, Juan Pedro

    2010-01-01

    The objectives of this study are to compare the Autobiographical Memory Test (AMT) performance of two healthy samples of younger and older adults and to analyse the relationship between overgeneral memory (OGM) and working memory executive processes (WMEP) using a structural equation modelling with latent variables. The AMT and sustained attention, short-term memory and working memory tasks were administered to a group of young adults (N = 50) and a group of older adults (N = 46). On the AMT, the older adults recalled a greater number of categorical memories (p = .000) and fewer specific memories (p = .000) than the young adults, confirming that OGM occurs in the normal population and increases with age. WMEP was measured by reading span and a working memory with sustained attention load task. Structural equation modelling reflects that WMEP shows a strong relationship with OGM: lower scores on WMEP reflect an OGM phenomenon characterized by higher categorical and lower specific memories. PMID:19626477

  17. Capillary ultrastructure and mitochondrial volume density in skeletal muscle in relation to reduced exercise capacity of patients with intermittent claudication.

    PubMed

    Baum, Oliver; Torchetti, Eleonora; Malik, Corinna; Hoier, Birgitte; Walker, Meegan; Walker, Philip J; Odriozola, Adolfo; Graber, Franziska; Tschanz, Stefan A; Bangsbo, Jens; Hoppeler, Hans; Askew, Christopher D; Hellsten, Ylva

    2016-05-15

    Intermittent claudication (IC) is the most commonly reported symptom of peripheral arterial disease (PAD). Impaired limb blood flow is a major casual factor of lower exercise tolerance in PAD but cannot entirely explain it. We hypothesized that IC is associated with structural changes of the capillary-mitochondria interface that could contribute to the reduction of exercise tolerance in IC patients. Capillary and mitochondrial morphometry were performed after light and transmission electron microscopy using vastus lateralis muscle biopsies of 14 IC patients and 10 age-matched controls, and peak power output (PPO) was determined for all participants using an incremental single-leg knee-extension protocol. Capillary density was lower (411 ± 90 mm(-2) vs. 506 ± 95 mm(-2); P ≤ 0.05) in the biopsies of the IC patients than in those of the controls. The basement membrane (BM) around capillaries was thicker (543 ± 82 nm vs. 423 ± 97 nm; P ≤ 0.01) and the volume density of mitochondria was lower (3.51 ± 0.56% vs. 4.60 ± 0.74%; P ≤ 0.01) in the IC patients than the controls. In the IC patients, a higher proportion of capillaries appeared with collapsed slit-like lumen and/or swollen endothelium. PPO was lower (18.5 ± 9.9 W vs. 33.5 ± 9.4 W; P ≤ 0.01) in the IC patients than the controls. We suggest that several structural alterations in skeletal muscle, either collectively or separately, contribute to the reduction of exercise tolerance in IC patients. PMID:27009051

  18. Comparison of Recovery Strategies on Maximal Force-Generating Capacity and Electromyographic Activity Level of the Knee Extensor Muscles

    PubMed Central

    Zarrouk, Nidhal; Rebai, Haithem; Yahia, Abdelmoneem; Souissi, Nizar; Hug, François; Dogui, Mohamed

    2011-01-01

    Context: With regard to intermittent training exercise, the effects of the mode of recovery on subsequent performance are equivocal. Objective: To compare the effects of 3 types of recovery intervention on peak torque (PT) and electromyographic (EMG) activity of the knee extensor muscles after fatiguing isokinetic intermittent concentric exercise. Design: Crossover study. Setting: Research laboratory. Patients or Other Participants: Eight elite judo players (age = 18.4 ± 1.4 years, height = 180 ± 3 cm, mass = 77.0 ± 4.2 kg). Interventions : Participants completed 3 randomized sessions within 7 days. Each session consisted of 5 sets of 10 concentric knee extensions at 80% PT at 120°/s, with 3 minutes of recovery between sets. Recovery interventions were passive, active, and electromyostimulation. The PT and maximal EMG activity were recorded simultaneously while participants performed isokinetic dynamometer trials before and 3 minutes after the resistance exercise. Main Outcome Measure(s): The PT and maximal EMG activity from the knee extensors were quantified at isokinetic velocities of 60°/s, 120°/s, and 180°/s, with 5 repetitions at each velocity. Results: The reduction in PT observed after electromyo-stimulation was less than that seen after passive (P < .001) or active recovery (P < .001). The reduction in PT was less after passive recovery than after active recovery (P < .001). The maximal EMG activity level observed after electromyostimulation was higher than that seen after active recovery (P < .05). Conclusions: Electromyostimulation was an effective recovery tool in decreasing neuromuscular fatigue after high-intensity, intermittent isokinetic concentric exercise for the knee extensor muscles. Also, active recovery induced the greatest amount of neuromuscular fatigue. PMID:21944070

  19. On the Capacity of Attention: Its Estimation and Its Role in Working Memory and Cognitive Aptitudes

    ERIC Educational Resources Information Center

    Cowan, N.; Elliott, E.M.; Scott Saults, J.; Morey, C.C.; Mattox, S.; Hismjatullina, A.; Conway, A.R.A.

    2005-01-01

    Working memory (WM) is the set of mental processes holding limited information in a temporarily accessible state in service of cognition. We provide a theoretical framework to understand the relation between WM and aptitude measures. The WM measures that have yielded high correlations with aptitudes include separate storage-and-processing task…

  20. Working Memory Capacity in Preschool Children Contributes to the Acquisition of School Relevant Precursor Skills

    ERIC Educational Resources Information Center

    Pressler, Anna-Lena; Krajewski, Kristin; Hasselhorn, Marcus

    2013-01-01

    The aim of the present study was to investigate whether preschool children with limitations in the visual or phonological working memory are disadvantaged in the acquisition of school relevant precursor skills at school entry. A sample of 92 children was divided into three subgroups depending on their performance in visual and phonological working…

  1. Development of a Handbook for Educators: Addressing Working Memory Capacity in Elementary Students

    ERIC Educational Resources Information Center

    Fernandez, Julie Marie

    2013-01-01

    Working Memory (WM) refers to a brain system that provides temporary storage and manipulation of the information necessary for complex cognitive tasks such as language comprehension, learning, and reasoning. WM also requires the simultaneous storage and processing of information. WM is directly related to academic performance in the classroom.…

  2. Working Memory Capacity and the Antisaccade Task: Individual Differences in Voluntary Saccade Control

    ERIC Educational Resources Information Center

    Unsworth, Nash; Schrock, Josef C.; Engle, Randall W.

    2004-01-01

    Performance on antisaccade trials requires the inhibition of a prepotent response (i.e., don't look at the flashing cue) and the generation and execution of a correct saccade in the opposite direction. The authors attempted to further specify the role of working memory (WM) span differences in the antisaccade task. They tested high- and low-span…

  3. Working Memory Capacity and Disfluency Effect: An Aptitude-Treatment-Interaction Study

    ERIC Educational Resources Information Center

    Lehmann, Janina; Goussios, Christina; Seufert, Tina

    2016-01-01

    According to Cognitive Load Theory, learning material should be designed in a way to decrease unnecessary demands on working memory (WM). However, recent research has shown that additional demands on WM caused by less legible texts lead to better learning outcomes. This so-called disfluency effect can be assumed as a metacognitive regulation…

  4. Interference Control, Working Memory Capacity, and Cognitive Abilities: A Latent Variable Analysis

    ERIC Educational Resources Information Center

    Unsworth, Nash

    2010-01-01

    The present study examined whether various indices of interference control were related to one another and to other cognitive abilities. It was found that the interference control measures were weakly correlated and could form a single factor that was related to overall memory performance on the tasks as well as to measures of working memory…

  5. Enacting Policy: The Capacity of School Leaders to Support Early Career Teachers through Policy Work

    ERIC Educational Resources Information Center

    Sullivan, Anna M.; Morrison, Chad

    2014-01-01

    Early career teachers often feel overwhelmed by the complex, intense and unpredictable nature of their work. Recently, policy initiatives have been introduced to provide new teachers with extra release-time from face-to-face classroom teaching duties to assist them in their transition to the workforce. This paper reports on a critical policy study…

  6. Attention and Working Memory Capacity: Insights from Blocking, Highlighting, and Knowledge Restructuring

    ERIC Educational Resources Information Center

    Sewell, David K.; Lewandowsky, Stephan

    2012-01-01

    The concept of attention is central to theorizing in learning as well as in working memory. However, research to date has yet to establish how attention as construed in one domain maps onto the other. We investigate two manifestations of attention in category- and cue-learning to examine whether they might provide common ground between learning…

  7. Effect of 8 weeks of pre-season training on body composition, physical fitness, anaerobic capacity, and isokinetic muscle strength in male and female collegiate taekwondo athletes

    PubMed Central

    Seo, Myong-Won; Jung, Hyun-Chul; Song, Jong-Kook; Kim, Hyun-Bae

    2015-01-01

    The purpose of the study was to determine the effect of 8 weeks pre-season training on body composition, physical fitness, anaerobic capacity, and isokinetic strength in collegiate taekwondo athletes. Thirty-four collegiate athletes (male: 22, female: 12) participated. Body composition, bone mineral density, physical fitness, anaerobic capacity, and isokinetic muscle strength were tested. After statistical analysis was performed the results indicated that there were significant decreases in body weight, percent body fat, and fat tissue after 8 weeks of pre-season training. Bone mineral density increased significantly only in males. There were significant improvements in the 50 m shuttle run and 20 m multistage endurance run in both males and females. The sit & reach test and standing long jump were not significantly changed after 8 weeks. Relative peak power and anaerobic capacity were significantly improved in males. Significant increases in angular velocity were observed for knee extension at both % BW 60°/sec and 180°/sec in both males and females. A significant increase in angular velocity was seen for right knee flexion at % BW 60°/sec for males, but it decreased at % BW 180°/sec for both males and females. In conclusion, this study suggests that 8 weeks of pre-season training has a positive effect on body composition, physical fitness, anaerobic capacity, isokinetic muscular strength, and endurance. Nevertheless, an exercise approach with the goal of increasing lean tissue, and improving power in knee flexors and flexibility of athletes, should be included in the training program. PMID:25960983

  8. Large capacity, multi-fuel, and high temperature working fluid heaters to optimize CSP plant cost, complexity and annual generation

    NASA Astrophysics Data System (ADS)

    Peterseim, J. H.; Viscuso, L.; Hellwig, U.; McIntyre, P.

    2016-05-01

    This paper analyses the potential to optimize high temperature fluid back-up systems for concentrating solar power (CSP) plants by investigating the cost impact of component capacity and the impact of using multiple fuels on annual generation. Until now back-up heaters have been limited to 20MWth capacity but larger units have been realised in other industries. Installing larger units yields economy-of-scale benefits through improved manufacturing, optimised transport, and minimized on-site installation work. Halving the number of back-up boilers can yield cost reduction of 23% while minimizing plant complexity and on-site construction risk. However, to achieve these benefits it is important to adapt the back-up heaters to the plant's requirements (load change, capacity, minimum load, etc.) and design for manufacture, transport and assembly. Despite the fact that biomass availability is decreasing with increasing direct normal irradiance (DNI), some biomass is available in areas suitable for CSP plants. The use of these biomass resources is beneficial to maximise annual renewable energy generation, substitute natural gas, and use locally/seasonally available biomass resources that may not be used otherwise. Even small biomass quantities of only 50,000 t/a can increase the capacity factor of a 50MWe parabolic trough plant with 7h thermal energy storage from 40 to 49%. This is a valuable increase and such a concept is suitable for new plants and retrofit applications. However, similar to the capacity optimisation of back-up heaters, various design criteria have to be considered to ensure a successful project.

  9. A genistein-enriched diet neither improves skeletal muscle oxidative capacity nor prevents the transition towards advanced insulin resistance in ZDF rats

    PubMed Central

    van Bree, Bianca W. J.; Lenaers, Ellen; Nabben, Miranda; Briedé, Jacco J.; Jörgensen, Johanna A.; Schaart, Gert; Schrauwen, Patrick; Hoeks, Joris; Hesselink, Matthijs K. C.

    2016-01-01

    Genistein, a natural food compound mainly present in soybeans, is considered a potent antioxidant and to improve glucose homeostasis. However, its mechanism of action remains poorly understood. Here, we analyzed whether genistein could antagonize the progression of the hyperinsulinemic normoglycemic state (pre-diabetes) toward full-blown T2DM in Zucker Diabetic Fatty (ZDF) rats by decreasing mitochondrial oxidative stress and improving skeletal muscle oxidative capacity. Rats were assigned to three groups: (1) lean control (CNTL), (2) fa/fa CNTL, and (3) fa/fa genistein (GEN). GEN animals were subjected to a 0.02% (w/w) genistein-enriched diet for 8 weeks, whereas CNTL rats received a standard diet. We show that genistein did not affect the overall response to a glucose challenge in ZDF rats. In fact, genistein may exacerbate glucose intolerance as fasting glucose levels were significantly higher in fa/fa GEN (17.6 ± 0.7 mM) compared with fa/fa CNTL animals (14.9 ± 1.4 mM). Oxidative stress, established by electron spin resonance (ESR) spectroscopy, carbonylated protein content and UCP3 levels, remained unchanged upon dietary genistein supplementation. Furthermore, respirometry measurements revealed no effects of genistein on mitochondrial function. In conclusion, dietary genistein supplementation did not improve glucose homeostasis, alleviate oxidative stress, or augment skeletal muscle metabolism in ZDF rats. PMID:26973284

  10. A genistein-enriched diet neither improves skeletal muscle oxidative capacity nor prevents the transition towards advanced insulin resistance in ZDF rats.

    PubMed

    van Bree, Bianca W J; Lenaers, Ellen; Nabben, Miranda; Briedé, Jacco J; Jörgensen, Johanna A; Schaart, Gert; Schrauwen, Patrick; Hoeks, Joris; Hesselink, Matthijs K C

    2016-01-01

    Genistein, a natural food compound mainly present in soybeans, is considered a potent antioxidant and to improve glucose homeostasis. However, its mechanism of action remains poorly understood. Here, we analyzed whether genistein could antagonize the progression of the hyperinsulinemic normoglycemic state (pre-diabetes) toward full-blown T2DM in Zucker Diabetic Fatty (ZDF) rats by decreasing mitochondrial oxidative stress and improving skeletal muscle oxidative capacity. Rats were assigned to three groups: (1) lean control (CNTL), (2) fa/fa CNTL, and (3) fa/fa genistein (GEN). GEN animals were subjected to a 0.02% (w/w) genistein-enriched diet for 8 weeks, whereas CNTL rats received a standard diet. We show that genistein did not affect the overall response to a glucose challenge in ZDF rats. In fact, genistein may exacerbate glucose intolerance as fasting glucose levels were significantly higher in fa/fa GEN (17.6 ± 0.7 mM) compared with fa/fa CNTL animals (14.9 ± 1.4 mM). Oxidative stress, established by electron spin resonance (ESR) spectroscopy, carbonylated protein content and UCP3 levels, remained unchanged upon dietary genistein supplementation. Furthermore, respirometry measurements revealed no effects of genistein on mitochondrial function. In conclusion, dietary genistein supplementation did not improve glucose homeostasis, alleviate oxidative stress, or augment skeletal muscle metabolism in ZDF rats. PMID:26973284

  11. Skeletal muscle alkaline Pi pool is decreased in overweight-to-obese sedentary subjects and relates to mitochondrial capacity and phosphodiester content

    PubMed Central

    Valkovič, Ladislav; Chmelík, Marek; Ukropcová, Barbara; Heckmann, Thomas; Bogner, Wolfgang; Frollo, Ivan; Tschan, Harald; Krebs, Michael; Bachl, Norbert; Ukropec, Jozef; Trattnig, Siegfried; Krššák, Martin

    2016-01-01

    Defects in skeletal muscle energy metabolism are indicative of systemic disorders such as obesity or type 2 diabetes. Phosphorus magnetic resonance spectroscopy (31P-MRS), in particularly dynamic 31P-MRS, provides a powerful tool for the non-invasive investigation of muscular oxidative metabolism. The increase in spectral and temporal resolution of 31P-MRS at ultra high fields (i.e., 7T) uncovers new potential for previously implemented techniques, e.g., saturation transfer (ST) or highly resolved static spectra. In this study, we aimed to investigate the differences in muscle metabolism between overweight-to-obese sedentary (Ob/Sed) and lean active (L/Ac) individuals through dynamic, static, and ST 31P-MRS at 7T. In addition, as the dynamic 31P-MRS requires a complex setup and patient exercise, our aim was to identify an alternative technique that might provide a biomarker of oxidative metabolism. The Ob/Sed group exhibited lower mitochondrial capacity, and, in addition, static 31P-MRS also revealed differences in the Pi-to-ATP exchange flux, the alkaline Pi-pool, and glycero-phosphocholine concentrations between the groups. In addition to these differences, we have identified correlations between dynamically measured oxidative flux and static concentrations of the alkaline Pi-pool and glycero-phosphocholine, suggesting the possibility of using high spectral resolution 31P-MRS data, acquired at rest, as a marker of oxidative metabolism. PMID:26838588

  12. Tennis in hot and cool conditions decreases the rapid muscle torque production capacity of the knee extensors but not of the plantar flexors

    PubMed Central

    Girard, Olivier; Racinais, Sébastien; Périard, Julien D

    2014-01-01

    Objectives To assess the time course of changes in rapid muscle force/torque production capacity and neuromuscular activity of lower limb muscles in response to prolonged (∼2 h) match-play tennis under heat stress. Methods The rates of torque development (RTD) and electromyographic activity (EMG; ie, root mean square) rise were recorded from 0 to 30, –50, –100 and –200 ms during brief (3–5 s) explosive maximal isometric voluntary contractions (MVC) of the knee extensors (KE) and plantar flexors (PF), along with the peak RTD within the entirety of the torque-time curve. These values were recorded in 12 male tennis players before (prematch) and after (postmatch, 24 and 48 h) match-play in HOT (∼37°C) and COOL (∼22°C) conditions. Results The postmatch core temperature was greater in the HOT (∼39.4°C) vs COOL (∼38.7°C) condition (p<0.05). Reductions in KE RTD occurred within the 0–200 ms epoch after contraction onset postmatch and at 24 h, compared with prematch, independent of environmental conditions (p<0.05). A similar reduction in the KE peak RTD was also observed postmatch relative to prematch (p<0.05). No differences in KE RTD values were observed after normalisation to MVC torque. Furthermore, the rate of KE EMG activity rise remained unchanged. Conversely, the PF contractile RTD and rate of EMG activity rise were unaffected by the exercise or environmental conditions. Conclusions In the KE, a reduction in maximal torque production capacity following prolonged match-play tennis appears to account for the decrease in the rate of torque development, independent of environmental conditions, while remaining unchanged in the PF. PMID:24668381

  13. Effects of Home-Based Interval Walking Training on Thigh Muscle Strength and Aerobic Capacity in Female Total Hip Arthroplasty Patients: A Randomized, Controlled Pilot Study

    PubMed Central

    Morishima, Yutaka; Mizushima, Takashi; Yamauchi, Katsuya; Morikawa, Mayuko; Masuki, Shizue; Nose, Hiroshi

    2014-01-01

    Due to the reduced physical activity of patients who have undergone total hip arthroplasty (THA), there are no home-based exercise training regimens for preventing muscle atrophy and aerobic capacity impairment in these patients. We examined whether interval walking training (IWT) could prevented these issues. Twenty-eight female patients (∼60 years of age) who had undergone THA more than 2 months prior were randomly divided into IWT (n = 14) and control (CNT, n = 14) groups. The IWT subjects trained at a target of 60 min of fast walking at >70% peak aerobic capacity for walking (O2peak) per wk for 12 wk, while those in the CNT maintained their previous sedentary life during the same period. We measured the energy expenditure of the daily physical activity, except during sleeping and bathing, every minute and every day during the intervention. We also measured the isometric knee extension (FEXT) and flexion (FFLX) forces, O2peak, and anaerobic threshold during the graded cycling exercise (O2AT) before and after the intervention. All subjects, except for one in IWT, completed the protocol. FFLX increased by 23% on the operated side (P = 0.003) and 14% on the non-operated side of IWT (P = 0.006), while it only increased on the operated side of CNT (P = 0.03). The O2peak and O2AT in IWT increased by 8% (P = 0.08) and 13% (P = 0.002), respectively, and these changes were significantly higher in the IWT than in CNT group (both, P<0.05). In conclusion, IWT might be an effective home-based training regimen for preventing the muscle atrophy from reduced daily physical activity in THA patients. Trial Registration UMIN-CTR UMIN000013172 PMID:25268505

  14. Work capacity during 30 days of bed rest with isotonic and isokinetic exercise training

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Bernauer, E. M.; Ertl, A. C.; Trowbridge, T. S.; Wade, C. E.

    1989-01-01

    Results are presented from a study to determine whether or not short-term variable intensity isotonic and intermittent high-intensity isokinetic short-duration leg exercise is effective for the maintenance of peak O2 (VO2) uptake and muscular strength and endurance, respectively, during 30 days of -6 deg head-down bed rest deconditioning. The results show no significant changes in leg peak torque, leg mean total work, arm total peak torque, or arm mean total work for members of the isotonic, isokinetic, and controls groups. Changes are observed, however, in peak VO2 levels. The results suggest that near-peak variabile intensity, isotonic leg excercise maintains peak VO2 during 30 days of bed rest, while peak intermittent, isokinetic leg excercise protocol does not.

  15. The Role of Mathematical Homework and Prior Knowledge on the Relationship between Students' Mathematical Performance, Cognitive Style and Working Memory Capacity

    ERIC Educational Resources Information Center

    Mousavi, Shima; Radmehr, Farzad; Alamolhodaei, Hasan

    2012-01-01

    Introduction: The main objective of this study is (a) to investigate whether cognitive styles and working memory capacity could predict mathematical performance and which variable is relatively most important in predicting mathematical performance and b) to explore whether cognitive styles and working memory capacity could predict mathematical…

  16. High muscle mitochondrial volume and aerobic capacity in a small marsupial (Sminthopsis crassicaudata) reveals flexible links between energy-use levels in mammals.

    PubMed

    Dawson, Terence J; Webster, Koa N; Lee, Enhua; Buttemer, William A

    2013-04-01

    We investigated the muscle structure-function relationships that underlie the aerobic capacity of an insectivorous, small (~15 g) marsupial, Sminthopsis crassicaudata (Family: Dasyuridae), to obtain further insight into energy use patterns in marsupials relative to those in placentals, their sister clade within the Theria (advanced mammals). Disparate hopping marsupials (Suborder Macropodiformes), a kangaroo (Macropus rufus) and a rat-kangaroo (Bettongia penicillata), show aerobic capabilities as high as those of 'athletic' placentals. Equivalent muscle mitochondrial volumes and cardiovascular features support these capabilities. We examined S. crassicaudata to determine whether highly developed aerobic capabilities occur elsewhere in marsupials, rather than being restricted to the more recently evolved Macropodiformes. This was the case. Treadmill-trained S. crassicaudata attained a maximal aerobic metabolic rate ( or MMR) of 272 ml O2 min(-1) kg(-1) (N=8), similar to that reported for a small (~20 g), 'athletic' placental, Apodemus sylvaticus, 264 ml O2 min(-1) kg(-1). Hopping marsupials have comparable aerobic levels when body mass variation is considered. Sminthopsis crassicaudata has a basal metabolic rate (BMR) about 75% of placental values but it has a notably large factorial aerobic scope (fAS) of 13; elevated fAS also features in hopping marsupials. The of S. crassicaudata was supported by an elevated total muscle mitochondrial volume, which was largely achieved through high muscle mitochondrial volume densities, Vv(mt,f), the mean value being 14.0±1.33%. These data were considered in relation to energy use levels in mammals, particularly field metabolic rate (FMR). BMR is consistently lower in marsupials, but this is balanced by a high fAS, such that marsupial MMR matches that of placentals. However, FMR shows different mass relationships in the two clades, with the FMR of small (<125 g) marsupials, such as S. crassicaudata, being higher than that in

  17. Mechanisms underlying comprehension of health information in adulthood: the roles of prior knowledge and working memory capacity.

    PubMed

    Soederberg Miller, Lisa M; Gibson, Tanja N; Applegate, Elizabeth A; de Dios, Jeannette

    2011-07-01

    Prior knowledge, working memory capacity (WMC), and conceptual integration (attention allocated to integrating concepts in text) are critical within many contexts; however, their impact on the acquisition of health information (i.e. learning) is relatively unexplored.We examined how these factors impact learning about nutrition within a cross-sectional study of adults ages 18 to 81. Results showed that conceptual integration mediated the effects of knowledge and WMC on learning, confirming that attention to concepts while reading is important for learning about health. We also found that when knowledge was controlled, age declines in learning increased, suggesting that knowledge mitigates the effects of age on learning about nutrition. PMID:21346017

  18. Integrated System Design: Promoting the Capacity of Sociotechnical Systems for Adaptation through Extensions of Cognitive Work Analysis.

    PubMed

    Naikar, Neelam; Elix, Ben

    2016-01-01

    This paper proposes an approach for integrated system design, which has the intent of facilitating high levels of effectiveness in sociotechnical systems by promoting their capacity for adaptation. Building on earlier ideas and empirical observations, this approach recognizes that to create adaptive systems it is necessary to integrate the design of all of the system elements, including the interfaces, teams, training, and automation, such that workers are supported in adapting their behavior as well as their structure, or organization, in a coherent manner. Current approaches for work analysis and design are limited in regard to this fundamental objective, especially in cases when workers are confronted with unforeseen events. A suitable starting point is offered by cognitive work analysis (CWA), but while this framework can support actors in adapting their behavior, it does not necessarily accommodate adaptations in their structure. Moreover, associated design approaches generally focus on individual system elements, and those that consider multiple elements appear limited in their ability to facilitate integration, especially in the manner intended here. The proposed approach puts forward the set of possibilities for work organization in a system as the central mechanism for binding the design of its various elements, so that actors can adapt their structure as well as their behavior-in a unified fashion-to handle both familiar and novel conditions. Accordingly, this paper demonstrates how the set of possibilities for work organization in a system may be demarcated independently of the situation, through extensions of CWA, and how it may be utilized in design. This lynchpin, conceptualized in the form of a diagram of work organization possibilities (WOP), is important for preserving a system's inherent capacity for adaptation. Future research should focus on validating these concepts and establishing the feasibility of implementing them in industrial contexts

  19. Integrated System Design: Promoting the Capacity of Sociotechnical Systems for Adaptation through Extensions of Cognitive Work Analysis

    PubMed Central

    Naikar, Neelam; Elix, Ben

    2016-01-01

    This paper proposes an approach for integrated system design, which has the intent of facilitating high levels of effectiveness in sociotechnical systems by promoting their capacity for adaptation. Building on earlier ideas and empirical observations, this approach recognizes that to create adaptive systems it is necessary to integrate the design of all of the system elements, including the interfaces, teams, training, and automation, such that workers are supported in adapting their behavior as well as their structure, or organization, in a coherent manner. Current approaches for work analysis and design are limited in regard to this fundamental objective, especially in cases when workers are confronted with unforeseen events. A suitable starting point is offered by cognitive work analysis (CWA), but while this framework can support actors in adapting their behavior, it does not necessarily accommodate adaptations in their structure. Moreover, associated design approaches generally focus on individual system elements, and those that consider multiple elements appear limited in their ability to facilitate integration, especially in the manner intended here. The proposed approach puts forward the set of possibilities for work organization in a system as the central mechanism for binding the design of its various elements, so that actors can adapt their structure as well as their behavior—in a unified fashion—to handle both familiar and novel conditions. Accordingly, this paper demonstrates how the set of possibilities for work organization in a system may be demarcated independently of the situation, through extensions of CWA, and how it may be utilized in design. This lynchpin, conceptualized in the form of a diagram of work organization possibilities (WOP), is important for preserving a system's inherent capacity for adaptation. Future research should focus on validating these concepts and establishing the feasibility of implementing them in industrial

  20. Commercial porters of eastern Nepal: health status, physical work capacity, and energy expenditure.

    PubMed

    Malville, N J; Byrnes, W C; Lim, H A; Basnyat, R

    2001-01-01

    The purpose of the study was to compare full-time hill porters in eastern Nepal with part-time casual porters engaged primarily in subsistence farming. The 50 porters selected for this study in Kenja (elevation 1,664 m) were young adult males of Tibeto-Nepali origin. Following standardized interviews, anthropometry, and routine physical examinations, the porters were tested in a field laboratory for physiological parameters associated with aerobic performance. Exercise testing, using a step test and indirect calorimetry, included a submaximal assessment of economy and a maximal-effort graded exercise test. Energy expenditure was measured in the field during actual tumpline load carriage. No statistically significant differences were found between full-time and part-time porters with respect to age, anthropometric characteristics, health, nutritional status, or aerobic power. Mean VO2 peak was 2.38 +/- 0.27 L/min (47.1 +/- 5.3 ml/kg/min). Load-carrying economy did not differ significantly between porter groups. The relationship between VO2 and load was linear over the range of 10-30 kg with a slope of 9 +/- 4 ml O2/min per kg of load. During the field test of actual work performance, porters expended, on average, 348 +/- 68 kcal/hr in carrying loads on the level and 408 +/- 60 kcal/hr in carrying loads uphill. Most porters stopped every 2 min, on average, to rest their loads briefly on T-headed resting sticks (tokmas). The technique of self-paced, intermittent exercise together with the modest increase in energy demands for carrying increasingly heavier loads allows these individuals to regulate work intensity and carry extremely heavy loads without creating persistent medical problems. PMID:11466966

  1. The Palau AHEC--academizing the public health work plan: capacity development and innovation in Micronesia.

    PubMed

    Dever, Greg; Finau, Sitaleki; Kuartei, Stevenson; Durand, A Mark; Rykken, David; Yano, Victor; Untalan, Pedro; Withy, Kelley; Tellei, Patrick; Baravilala, Wame; Pierantozzi, Sandra; Tellei, Jullie

    2005-03-01

    The Palau Area Health Education Center (AHEC)--a program of the University of Hawaii's John A. Burns School of Medicine (JABSOM) and based at Palau Community College--was established in 2001 in response to the recommendations of the 1998 Institute of Medicine (IOM) report--Pacific Partnerships for Health--Charting a New Course for the 21st Century1. One of IOM's core recommendations was to promote the training of the primary health care workforce among the U.S.-Associated Pacific Islands. Since its inception in 2001, the Palau AHEC has coordinated overall 37 postgraduate and undergraduate courses in General Practice and Public Health taught by the University of Auckland Faculty of Medicine and Health Sciences and the Fiji School of Medicine's School of Public Health and Primary Care (SPH&PC) in Palau, Yap State, and the Republic of the Marshall Islands. Currently 139 physicians, nurses, health administrators, and environmental health workers are registered as active students in Palau (58), Yap State (22), and the RMI (59). Notably, the Palau AHEC and the SPH&PC have worked in an innovative partnership with the Palau Ministry of Health to operationalize the MOH's public health work plan to implement a comprehensive community health survey of all 4,376 households in Palau, interviewing 79% of the total population, to determine Palau's health indicators. To accomplish this, the SPH&PC developed and taught a curriculum for Palau physicians and public health nurses on how to design the survey, gather, and analyze data in order to develop and implement appropriately responsive intervention and treatment programs to address Palau's old and newer morbidities. In early FY2005, two other Micronesian AHECs--the Yap St