Matching initial torque with different stimulation parameters influences skeletal muscle fatigue.

PubMed

Bickel, C Scott; Gregory, Chris M; Azuero, Andres

2012-01-01

A fundamental barrier to using electrical stimulation in the clinical setting is an inability to maintain torque production secondary to muscle fatigue. Electrical stimulation parameters are manipulated to influence muscle torque production, and they may also influence fatigability during repetitive stimulation. Our purpose was to determine the response of the quadriceps femoris to three different fatigue protocols using the same initial torque obtained by altering stimulator parameter settings. Participants underwent fatigue protocols in which either pulse frequency (lowHz), pulse duration (lowPD), or voltage (lowV) was manipulated to obtain an initial torque that equaled 25% of maximum voluntary isometric contraction. Muscle soreness was reported on a visual analog scale 48 h after each fatigue test. The lowHz protocol resulted in the least fatigue (25% +/- 14%); the lowPD (50% +/- 13%) and lowV (48% +/- 14%) protocols had similar levels of fatigue. The lowHz protocol resulted in significantly less muscle soreness than the higher frequency protocols. Stimulation protocols that use a lower frequency coupled with long pulse durations and high voltages result in lesser amounts of muscle fatigue and perceived soreness. The identification of optimal stimulation patterns to maximize muscle performance will reduce the effect of muscle fatigue and potentially improve clinical efficacy.

Neuromuscular function of the quadriceps muscle during isometric maximal, submaximal and submaximal fatiguing voluntary contractions in knee osteoarthrosis patients

PubMed Central

Jacksteit, Robert; Jackszis, Mario; Feldhege, Frank; Weippert, Matthias; Mittelmeier, Wolfram; Bader, Rainer; Skripitz, Ralf; Behrens, Martin

2017-01-01

.049). Conclusion KOA is not only associated with a deterioration of IMVT and neuromuscular activation, but also with an impaired position and torque control at submaximal torque levels, an altered EMG-torque relationship and a higher performance fatigability of the quadriceps muscle. It is recommended that the rehabilitation includes strengthening and fatiguing exercises at maximal and submaximal force levels. PMID:28505208

Acute fatigue impairs neuromuscular activity of anterior cruciate ligament-agonist muscles in female team handball players.

PubMed

Zebis, M K; Bencke, J; Andersen, L L; Alkjaer, T; Suetta, C; Mortensen, P; Kjaer, M; Aagaard, P

2011-12-01

In sports, like team handball, fatigue has been associated with an increased risk of anterior cruciate ligament (ACL) injury. While effects of fatigue on muscle function are commonly assessed during maximal isometric voluntary contraction (MVC), such measurements may not relate to the muscle function during match play. The purpose of this study was to investigate the effect of muscle fatigue induced by a simulated handball match on neuromuscular strategy during a functional sidecutting movement, associated with the incidence of ACL injury. Fourteen female team handball players were tested for neuromuscular activity [electromyography (EMG)] during a sidecutting maneuver on a force plate, pre and post a simulated handball match. MVC was obtained during maximal isometric quadriceps and hamstring contraction. The simulated handball match consisted of exercises mimicking handball match activity. Whereas the simulated handball match induced a decrease in MVC strength for both the quadriceps and hamstring muscles (P<0.05), a selective decrease in hamstring neuromuscular activity was seen during sidecutting (P<0.05). This study shows impaired ACL-agonist muscle (i.e. hamstring) activity during sidecutting in response to acute fatigue induced by handball match play. Thus, screening procedures should involve functional movements to reveal specific fatigue-induced deficits in ACL-agonist muscle activation during high-risk phases of match play. © 2010 John Wiley & Sons A/S.

Fatigue-induced changes in decline running.

PubMed

Mizrahi, J; Verbitsky, O; Isakov, E

2001-03-01

Study the relation between muscle fatigue during eccentric muscle contractions and kinematics of the legs in downhill running. Decline running on a treadmill was used to acquire data on shock accelerations, muscle activity and kinematics, for comparison with level running. In downhill running, local muscle fatigue is the cause of morphological muscle damage which leads to reduced attenuation of shock accelerations. Fourteen subjects ran on a treadmill above level-running anaerobic threshold speed for 30 min, in level and -4 degrees decline running. The following were monitored: metabolic fatigue by means of respiratory parameters; muscle fatigue of the quadriceps by means of elevation in myoelectric activity; and kinematic parameters including knee and ankle angles and hip vertical excursion by means of computerized videography. Data on shock transmission reported in previous studies were also used. Quadriceps fatigue develops in parallel to an increasing vertical excursion of the hip in the stance phase of running, enabled by larger dorsi flexion of the ankle rather than by increased flexion of the knee. The decrease in shock attenuation can be attributed to quadriceps muscle fatigue in parallel to increased vertical excursion of the hips.

Atrophy of the quadriceps muscle in children with a painful hip.

PubMed

Robben, S G; Lequin, M H; Meradji, M; Diepstraten, A F; Hop, W C

1999-09-01

The objective of this study was to determine the degree of muscle wasting of various components of the quadriceps muscle in children with a painful hip. Between January 1994 and September 1997, 327 consecutive children with a unilateral painful hip and/or limping were evaluated prospectively with ultrasonography. Quadriceps thickness was measured on both sides. Moreover, muscle thickness was measured in 59 control subjects. The patients were divided into eight groups; transient synovitis (n = 134), Perthes' disease (n = 35), slipped capital femoral epiphysis (n = 5), osteomyelitis (n = 4), aspecific synovitis (n = 5), rheumatoid arthritis (n = 3) and miscellaneous (n = 16). In 125 patients, no sonographic and radiological abnormalities were found and during follow-up the symptoms disappeared ('no pathology' group). Ipsilateral muscle wasting was present in all patient groups, whereas the control subjects showed no significant difference in muscle thickness between legs. The degree of muscle wasting was compared between transient synovitis, the 'no pathology' group, Perthes' disease and control subjects. For both quadriceps and vastus intermedius muscles, there was a significant difference between these groups, except between control subjects and the 'no pathology' group. For the rectus femoris muscle, there was a significant difference between these groups, except between transient synovitis and 'no pathology'. Muscle wasting showed a positive correlation with duration of symptoms and pre-existing muscle mass. In conclusion, different diseases show different degrees of muscle wasting, and there are different patterns of muscle wasting of various components of the quadriceps femoris muscle.

Quadriceps intramuscular fat fraction rather than muscle size is associated with knee osteoarthritis

PubMed Central

Kumar, Deepak; Karampinos, Dimitrios C.; MacLeod, Toran D.; Lin, Wilson; Nardo, Lorenzo; Li, Xiaojuan; Link, Thomas M; Majumdar, Sharmila; Souza, Richard B

2014-01-01

Objectives To compare thigh muscle intramuscular fat (intraMF) fractions and area between people with and without knee radiographic osteoarthritis (ROA); and to evaluate the relationships of quadriceps adiposity and area with strength, function and knee MRI lesions. Methods Ninety six subjects (ROA: KL >1; n = 30, control: KL = 0,1; n = 66) underwent 3-Tesla MRI of the thigh muscles using chemical shift-based water/fat MR imaging (fat fractions) and the knee (clinical grading). Subjects were assessed for isometric/isokinetic quadriceps/hamstrings strength, function (KOOS, stair climbing test [SCT], and 6-minute walk test [(6MWT]. Thigh muscle intraMF fractions, muscle area and strength, and function were compared between controls and ROA subjects, adjusting for age. Relationships between measures of muscle fat/area with strength, function, KL and lesion scores were assessed using regression and correlational analyses. Results The ROA group had worse KOOS scores but SCT and 6MWT were not different. The ROA group had greater quadriceps intraMF fraction but not for other muscles. Quadriceps strength was lower in ROA group but the area was not different. Quadriceps intraMF fraction but not area predicted self-reported disability. Aging, worse KL, and cartilage and meniscus lesions were associated with higher quadriceps intraMF fraction. Conclusion Quadriceps intraMF is higher in people with knee OA and is related to symptomatic and structural severity of knee OA, where as the quadriceps area is not. Quadriceps fat fraction from chemical shift-based water/fat MR imaging may have utility as a marker of structural and symptomatic severity of knee OA disease process. PMID:24361743

Effect of eccentric exercise with reduced muscle glycogen on plasma interleukin-6 and neuromuscular responses of musculus quadriceps femoris.

PubMed

Gavin, James P; Myers, Stephen D; Willems, Mark E T

2016-07-01

Eccentric exercise can result in muscle damage and interleukin-6 (IL-6) secretion. Glycogen availability is a potent stimulator of IL-6 secretion. We examined effects of eccentric exercise in a low-glycogen state on neuromuscular function and plasma IL-6 secretion. Twelve active men (23 ± 4 yr, 179 ± 5 cm, 77 ± 10 kg, means ± SD) completed two downhill treadmill runs (gradient, -12%, 5 × 8 min; speed, 12.1 ± 1.1 km/h) with normal (NG) and reduced muscle glycogen (RG) in randomized order and at least 6 wk apart. Muscle glycogen was reduced using an established cycling protocol until exhaustion and dietary manipulation the evening before the morning run. Physiological responses were measured up to 48 h after the downhill runs. During recovery, force deficits of musculus quadriceps femoris by maximal isometric contractions were similar. Changes in low-frequency fatigue were larger with RG. Voluntary activation and plasma IL-6 levels were similar in recovery between conditions. It is concluded that unaccustomed, damaging eccentric exercise with low muscle glycogen of the m. quadriceps femoris 1) exacerbated low-frequency fatigue but 2) had no additional effect on IL-6 secretion. Neuromuscular impairment after eccentric exercise with low muscle glycogen appears to have a greater peripheral component in early recovery. Copyright © 2016 the American Physiological Society.

Effects of knee and ankle muscle fatigue on postural control in the unipedal stance.

PubMed

Bizid, Riadh; Margnes, Eric; François, Yrieix; Jully, Jean Louis; Gonzalez, Gerard; Dupui, Philippe; Paillard, Thierry

2009-06-01

The aim of this study was to compare the effects of acute muscle fatigue of the ankle and knee musculature on postural control by immediate measures after performing fatiguing tasks (POST condition). One group of subjects (n = 8) performed a fatiguing task by voluntary contractions of the triceps surae (group TRI) and the other (n = 9) performed a fatiguing task by voluntary contractions of the quadriceps femoris (group QUA). Each muscle group was exercised until the loss of maximal voluntary contraction torque reached 50% (isokinetic dynamometer). Posture was assessed by measuring the centre of foot pressure (COP) with a force platform during a test of unipedal quiet standing posture with eyes closed. Initially (in PRE condition), the mean COP velocity was not significantly different between group TRI and group QUA. In POST condition, the mean COP velocity increased more in group QUA than in group TRI. The postural control was more impaired by knee muscle fatigue than by ankle muscle fatigue.

Effects of stretching and fatigue on peak torque, muscle imbalance, and stability.

PubMed

Costa, Pablo B; Ruas, Cassio V; Smith, Cory M

2018-01-01

The present study examined the acute effects of hamstrings stretching and fatigue on knee extension and flexion peak torque (PT), hamstrings to quadriceps (H:Q) ratio, and postural stability. Seventeen women (mean±SD age=21.8±2.1 years; body mass=63.0±10.5 kg; height=164.7±6.2 cm) and eighteen men (25.8±4.6 years; 83.6±13.2 kg; 175.3±6.0 cm) took part in three laboratory visits. The first visit was a familiarization session, and the subsequent two visits were randomly assigned as a control or stretching condition. For the testing visits, subjects performed a postural stability assessment, stretched (or sat quietly during the control condition), performed a 50-repetition unilateral isokinetic fatigue protocol, and repeated the postural stability assessment. There were no significant differences between control and stretching conditions for initial quadriceps and hamstrings PT, initial H:Q ratio, quadriceps and hamstrings PT fatigue indexes, H:Q ratio Fatigue Index, rating of perceived exertion (RPE), or postural stability (P>0.05). When analyzing 5 intervals of 10 repetitions, significant declines in quadriceps PT were found in all intervals for both conditions (P<0.05). However, a decline in hamstrings PT was only found until the fourth interval (i.e., repetitions 31 to 40) for the stretching condition (P<0.05). Stretching the hamstrings immediately prior to long-duration activities may eventually cause adverse effects in force-generating capacity of this muscle group to occur earlier when fatiguing tasks are involved. Nevertheless, no changes were found for the H:Q ratios after stretching when compared to no-stretching.

Objectively measured muscle fatigue in Crohn's disease: correlation with self-reported fatigue and associated factors for clinical application.

PubMed

van Langenberg, D R; Della Gatta, P; Warmington, S A; Kidgell, D J; Gibson, P R; Russell, A P

2014-02-01

The association of fatigue with decreased physical performance and underlying mechanisms are poorly understood in Crohn's disease (CD). We aimed to measure and compare self-reported fatigue with skeletal muscle fatigue in CD subjects and healthy controls, and to identify associated factors that may be amenable to change. Demographic and clinical data were collected and fatigue assessed using the Fatigue Impact Scale (FIS) in 27 consecutive CD patients and 22 matched healthy controls. Circulating cytokines and growth factors were measured. The rate of quadriceps muscle fatigue was assessed using an isokinetic dynamometer as the decrement of force with 30 contractions performed over a 5-minute period. Compared with healthy controls, CD patients reported greater levels of fatigue (mean global FIS score 45.3 vs 10.5, physical dimension score 12.3 vs 2.7 respectively; each p<0.01) and muscle fatigue (-5.2 vs -1.3 Nm min(-1); p<0.05). The two indices were correlated (r = -0.52 in CD; p<0.01). Patients with CD had lower mean serum IGF-1 levels (16.1 vs 25.4 pmol/L, p<0.01) and higher oxidative stress (TBARS assay 4.3 vs 3.9 μM, p<0.05). On multivariate analysis, low serum vitamin D, IGF-1 and magnesium, and higher IL-6 levels were associated with increased muscle fatigue (all p ≤ 0.05). Subjects with CD had more muscle fatigue than matched healthy controls and this correlated well with self-reported fatigue. Of circulating factors that were independently associated with increased muscle fatigue, vitamin D, magnesium and IGF-1 could be targeted in future studies to reduce fatigue and improve physical performance. © 2013.

Quality of life, muscle strength, and fatigue perception in patients on suppressive therapy with levothyroxine for differentiated thyroid carcinoma.

PubMed

de Oliveira Chachamovitz, Dhiãnah Santini; dos Santos Vigário, Patrícia; Nogueira Cordeiro, Mônica Fabíola; de Castro, Carmen Lucia Natividade; Vaisman, Mário; dos Santos Teixeira, Patrícia de Fátima

2013-08-01

The aim of this study was to evaluate the fatigue perception, the muscle function, and the health-related quality of life (QoL) in subclinical hyperthyroidism (SCH) induced by levothyroxine in the treatment of differentiated thyroid carcinoma, in comparison with a group of euthyroid (EU) subjects. A cross-sectional study with 38 SCH individuals and 54 EU subjects was performed. They were submitted to Short Form-36 and Chalder questionnaires to evaluate QoL and fatigue, respectively. The tests performed to evaluate muscle function of upper and lower limbs were: maximum quadriceps isometric strength (QS); quadriceps fatigue resistance (T50% QS), QS at 30 seconds (QS30s); quadriceps functional capacity (QFC); maximum isometric handgrip strength (HS); fatigue handgrip resistance (T50% HS), HS at 30 seconds (HS30s); and functional capacity of the shoulder. The SCH patients had worse muscle function, regarding HS (25.19 ± 7.00 vs. 30.45 ± 9.98 kgf in EU, P = 0.009) and functional capacity of the shoulder (41.28 ± 48.36 vs. 56.68 ± 37.44 s in EU, P = 0.004). The self-perception of fatigue by Chalder questionnaire (23.91 ± 5.39 vs. 29.77 ± 7.03, P = 0.000) and the QoL in terms of functional capacity (70.20 ± 21.57 vs. 56.25 ± 28.79, P = 0.025), physical aspects (71.42 ± 36.44 vs. 45.83 ± 42.88, P = 0.004), pain (62.48 ± 22.20 vs. 50.05 ± 24.80, P = 0.035), and emotional aspects (70.74 ± 38.26 vs. 46.29 ± 44.56, P = 0.008) were also worse in SCH. In conclusion, the SCH was associated with alterations in the QoL, reduction in the muscle function of upper limbs, and higher degree of fatigue.

Dissociation between short-term unloading and resistance training effects on skeletal muscle Na+,K+-ATPase, muscle function, and fatigue in humans.

PubMed

Perry, Ben D; Wyckelsma, Victoria L; Murphy, Robyn M; Steward, Collene H; Anderson, Mitchell; Levinger, Itamar; Petersen, Aaron C; McKenna, Michael J

2016-11-01

Physical training increases skeletal muscle Na + ,K + -ATPase content (NKA) and improves exercise performance, but the effects of inactivity per se on NKA content and isoform abundance in human muscle are unknown. We investigated the effects of 23-day unilateral lower limb suspension (ULLS) and subsequent 4-wk resistance training (RT) on muscle function and NKA in 6 healthy adults, measuring quadriceps muscle peak torque; fatigue and venous [K + ] during intense one-legged cycling exercise; and skeletal muscle NKA content ([ 3 H]ouabain binding) and NKA isoform abundances (immunoblotting) in muscle homogenates (α 1-3 , β 1-2 ) and in single fibers (α 1-3 , β 1 ). In the unloaded leg after ULLS, quadriceps peak torque and cycling time to fatigue declined by 22 and 23%, respectively, which were restored with RT. Whole muscle NKA content and homogenate NKA α 1-3 and β 1-2 isoform abundances were unchanged with ULLS or RT. However, in single muscle fibers, NKA α 3 in type I (-66%, P = 0.006) and β 1 in type II fibers (-40%, P = 0.016) decreased after ULLS, with other NKA isoforms unchanged. After RT, NKA α 1 (79%, P = 0.004) and β 1 (35%, P = 0.01) increased in type II fibers, while α 2 (76%, P = 0.028) and α 3 (142%, P = 0.004) increased in type I fibers compared with post-ULLS. Despite considerably impaired muscle function and earlier fatigue onset, muscle NKA content and homogenate α 1 and α 2 abundances were unchanged, thus being resilient to inactivity induced by ULLS. Nonetheless, fiber type-specific downregulation with inactivity and upregulation with RT of several NKA isoforms indicate complex regulation of muscle NKA expression in humans. Copyright © 2016 the American Physiological Society.

Serial Changes of Quadriceps and Hamstring Muscle Strength Following Total Knee Arthroplasty: A Meta-Analysis

PubMed Central

Ahn, Hyeong-Sik; Lee, Dae-Hee

2016-01-01

This meta-analysis was performed to analyze serial changes in thigh muscles, including quadriceps and hamstring muscles, from before to one year after total knee arthroplasty (TKA). All studies sequentially comparing isokinetic quadriceps and hamstring muscle strengths between the TKA side and the contralateral uninjured limb were included in this meta-analysis. Five studies with 7 cohorts were included in this meta-analysis. The mean differences in the strengths of quadriceps and hamstring muscles between the TKA and uninjured sides were greatest three months after surgery (26.8 N∙m, 12.8 N∙m, P<0.001), but were similar to preoperative level at six months (18.4 N∙m, 7.4 N∙m P<0.001) and were maintained for up to one year (15.9 N∙m, 4.1 N∙m P<0.001). The pooled mean differences in changes in quadriceps and hamstring strengths relative to preoperative levels were 9.2 N∙m and 4.9 N∙m, respectively, three months postoperatively (P = 0.041), but were no longer significant after six months and one year. During the year after TKA, quadriceps and hamstring muscle strengths were lowest after 3 months, recovering to preoperative level after six months, but not reaching the muscle strength on the contralateral side. Relative to preoperative levels, the difference in muscle strength between the TKA and contralateral knees was only significant at three months. Because decrease of strength of the quadriceps was significantly greater than decrease in hamstring muscle strength at postoperative three months, early rehabilitation after TKA should focus on recovery of quadriceps muscle strength. PMID:26849808

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.

Assessment of muscle endurance of the knee extensor muscles in adolescents with spastic cerebral palsy using a submaximal repetitions-to-fatigue protocol.

PubMed

Eken, Maaike M; Dallmeijer, Annet J; Doorenbosch, Caroline A; Dekkers, Hurnet; Becher, Jules G; Houdijk, Han

2014-10-01

To compare muscle endurance in adolescents with spastic cerebral palsy (CP) with typically developing (TD) peers using a submaximal repetitions-to-fatigue (RTF) protocol. Cross sectional. Human motion laboratory. Adolescents with spastic CP (n=16; Gross Motor Function Classification System levels I or II) and TD adolescents (n=18) within the age range of 12 to 19 years old. Not applicable. Each participant performed 3 RTF tests at different submaximal loads, ranging from 50% to 90% of their maximal voluntary knee extension torque. The relation between the number of repetitions (repetition maximum [RM]) and imposed submaximal relative (percent of maximal voluntary torque [%MVT]) and absolute (Nm/kg) torque was quantified. To compare adolescents with CP with TD adolescents, a mixed linear model was used to construct load endurance curves. Surface electromyography of quadriceps muscles was measured to assess changes in normalized amplitude and median frequency (MF) as physiological indicators of muscle fatigue. Adolescents with CP showed a larger decrease in %MVT per RM than TD adolescents (P<.05). TD adolescents showed substantial higher absolute (Nm/kg) load endurance curves than adolescents with CP (P<.001), but they did not show a difference in slope. Electromyographic normalized amplitude increased significantly (P<.05) in the quadriceps muscles in all tests for both groups. Electromyographic MF decreased significantly (P<.05) in tests with the low and medium loads. Electromyographic responses did not differ between groups, indicating that similar levels of muscle fatigue were reached. Adolescents with CP show slightly lower muscle endurance compared with TD adolescents on a submaximal RTF protocol, which is in contrast with earlier findings in a maximal voluntary fatigue protocol. Accordingly, adolescents with CP have a reduced capacity to endure activities at similar relative loads compared with TD adolescents. Copyright © 2014 American Congress of

Central and peripheral quadriceps fatigue in congestive heart failure☆

PubMed Central

Hopkinson, Nicholas S.; Dayer, Mark J.; Antoine-Jonville, Sophie; Swallow, Elisabeth B.; Porcher, Raphael; Vazir, Ali; Poole-Wilson, Philip; Polkey, Michael I.

2013-01-01

Aims The clinical syndrome of heart failure includes exercise limitation that is not directly linked to measures of cardiac function. Quadriceps fatigability may be an important component of this and this may arise from peripheral or central factors. Methods and results We studied 10 men with CHF and 10 healthy age-matched controls. Compared with a rest condition, 10 min after incremental maximal cycle exercise, twitch quadriceps force in response to supramaximal magnetic femoral nerve stimulation fell in both groups (CHF 14.1% ± 18.1%, p = 0.037; Control: 20.8 ± 11.0%, p < 0.001; no significant difference between groups). There was no significant change in quadriceps maximum voluntary contraction voluntary force. The difference in the motor evoked potential (MEP) response to transcranial magnetic stimulation of the motor cortex between rest and exercise conditions at 10 min, normalised to the peripheral action potential, also fell significantly in both groups (CHF: 27.3 ± 38.7%, p = 0.037; Control: 41.1 ± 47.7%, p = 0.024). However, the fall in MEP was sustained for a longer period in controls than in patients (p = 0.048). Conclusions The quadriceps is more susceptible to fatigue, with a similar fall in TwQ occurring in CHF patients at lower levels of exercise. This is associated with no change in voluntary activation but a lesser degree of depression of quadriceps motor evoked potential. PMID:22795722

Preferential reduction of quadriceps over respiratory muscle strength and bulk after lung transplantation for cystic fibrosis.

PubMed

Pinet, C; Scillia, P; Cassart, M; Lamotte, M; Knoop, C; Mélot, C; Estenne, M

2004-09-01

In the absence of complications, recipients of lung transplants for cystic fibrosis have normal pulmonary function but the impact of the procedure on the strength and bulk of respiratory and limb muscles has not been studied. Twelve stable patients who had undergone lung transplantation for cystic fibrosis 48 months earlier (range 8-95) and 12 normal subjects matched for age, height, and sex were studied. The following parameters were measured: standard lung function, peak oxygen uptake by cycle ergometry, diaphragm surface area by computed tomographic (CT) scanning, diaphragm and abdominal muscle thickness by ultrasonography, twitch transdiaphragmatic and gastric pressures, quadriceps isokinetic strength, and quadriceps cross section by CT scanning, and lean body mass. Diaphragm mass was computed from diaphragm surface area and thickness. Twitch transdiaphragmatic and gastric pressures, diaphragm mass, and abdominal muscle thickness were similar in the two groups but quadriceps strength and cross section were decreased by nearly 30% in the patients. Patients had preserved quadriceps strength per unit cross section but reduced quadriceps cross section per unit lean body mass. The cumulative dose of corticosteroids was an independent predictor of quadriceps atrophy. Peak oxygen uptake showed positive correlations with quadriceps strength and cross section in the two groups, but peak oxygen uptake per unit quadriceps strength or cross section was reduced in the patient group. The diaphragm and abdominal muscles have preserved strength and bulk in patients transplanted for cystic fibrosis but the quadriceps is weak due to muscle atrophy. This atrophy is caused in part by corticosteroid therapy and correlates with the reduction in exercise capacity.

ASSOCIATION BETWEEN LONG-TERM QUADRICEPS WEAKNESS AND EARLY WALKING MUSCLE CO-CONTRACTION AFTER TOTAL KNEE ARTHROPLASTY

PubMed Central

Yoshida, Yuri; Mizner, Ryan L.; Snyder-Mackler, Lynn

2013-01-01

INTRODUCTION Quadriceps weakness is one of the primary post-operative impairments that persist long term for patients after total knee arthroplasty (TKA). We hypothesized that early gait muscle recruitment patterns of the quadriceps and hamstrings with diminished knee performance at 3 months after surgery would be related to long-term quadriceps strength at one year after TKA. METHODS Twenty-one subjects who underwent primary unilateral TKA and 14 age-matched healthy controls were analyzed. At three months after TKA, the maximum voluntary isometric contraction of quadriceps and a comprehensive gait analysis were performed. Quadriceps strength was assessed again at one year after surgery. RESULTS Quadriceps muscle recruitment of the operated limb was greater than the non-operated limb during the loading response of gait (p=0.03), but there were no significant differences in hamstring recruitment or co-contraction between limbs (p>0.05). There were significant differences in quadriceps muscle recruitment during gait between the non-operated limb of TKA group and healthy control group (p<0.05). The TKA group showed a significant inverse relationship between one year quadriceps strength and co-contraction (r = −0.543) and hamstring muscle recruitment (r = −0.480) during loading response at 3 months after TKA. CONCLUSIONS The results revealed a reverse relationship where stronger patients tended to demonstrate lower quadriceps recruitment at 3 months post-surgery that was not observed in the healthy peer group. The altered neuromuscular patterns of quadriceps and hamstrings during gait may influence chronic quadriceps strength in individuals after TKA. PMID:23352711

Tribute to Dr Jacques Rogge: muscle activity and fatigue during hiking in Olympic dinghy sailing.

PubMed

Bourgois, Jan G; Dumortier, Jasmien; Callewaert, Margot; Celie, Bert; Capelli, Carlo; Sjøgaard, Gisela; De Clercq, Dirk; Boone, Jan

2017-06-01

'A tribute to Dr J. Rogge' aims to systematically review muscle activity and muscle fatigue during sustained submaximal quasi-isometric knee extension exercise (hiking) related to Olympic dinghy sailing as a tribute to Dr Rogge's merits in the world of sports. Dr Jacques Rogge is not only the former President of the International Olympic Committee, he was also an orthopaedic surgeon and a keen sailor, competing at three Olympic Games. In 1972, in fulfilment of the requirements for the degree of Master in Sports Medicine, he was the first who studied a sailors' muscle activity by means of invasive needle electromyography (EMG) during a specific sailing technique (hiking) on a self-constructed sailing ergometer. Hiking is a bilateral and multi-joint submaximal quasi-isometric movement which dinghy sailors use to optimize boat speed and to prevent the boat from capsizing. Large stresses are generated in the anterior muscles that cross the knee and hip joint, mainly employing the quadriceps at an intensity of 30-40% maximal voluntary contraction (MVC), sometimes exceeding 100% MVC. Better sailing level is partially determined by a lower rate of neuromuscular fatigue during hiking and for ≈60% predicted by a higher maximal isometric quadriceps strength. Although useful in exercise testing, prediction of hiking endurance capacity based on the changes in surface EMG in thigh and trunk muscles during a hiking maintenance task is not reliable. This could probably be explained by the varying exercise intensity and joint angles, and the great number of muscles and joints involved in hiking. Highlights Dr Jacques Rogge, former president of the International Olympic Committee and Olympic Finn sailor, was the first to study muscle activity during sailing using invasive needle EMG to obtain his Master degree in Sports Medicine at the Ghent University. Hiking is a critical bilateral and multi-joint movement during dinghy racing, accounting for >60% of the total upwind leg time

Quadriceps muscle injury in trans-femoral amputees.

PubMed

Alsindi, Z; Datta, D

1998-12-01

Two male trans-femoral amputees using modular trans-femoral prostheses lost control and fell to the ground when their prosthetic knees gave way. The semi-automatic knee lock malfunctioned in the first case while the free knee stabilising mechanics gave way in the second case. This resulted in a high tensile force acting on the contralateral quadriceps muscle causing it to rupture. As there are a significant number of patients with both kinds of prostheses it is important to be aware of this possibility so that necessary actions can be taken to minimise its occurrence. Even with the currently available weight activated stance phase control, the prosthetic knee will give way if the knee is flexed more than 20 degrees on weight bearing. Good power and control of hip extensors on the amputation side is needed to control the prosthetic knee joint, especially in the early stage of the walking cycle, i.e., from heel strike to mid-stance. Quadriceps muscle injury in amputees, as far as the authors are aware, has not been reported previously.

Influence of Anterior Cruciate Ligament Tear on Thigh Muscle Strength and Hamstring-to-Quadriceps Ratio: A Meta-Analysis.

PubMed

Kim, Hyun-Jung; Lee, Jin-Hyuck; Ahn, Sung-Eun; Park, Min-Ji; Lee, Dae-Hee

2016-01-01

Theoretical compensation after anterior cruciate ligament (ACL) tear could cause quadriceps weakness and hamstring activation, preventing anterior tibial subluxation and affecting the expected hamstring-to-quadriceps ratio. Although quadriceps weakness often occurs after ACL tears, it remains unclear whether hamstring strength and hamstring-to-quadriceps ratio increase in ACL deficient knees. This meta-analysis compared the isokinetic muscle strength of quadriceps and hamstring muscles, and the hamstring-to-quadriceps ratio, of the injured and injured limbs of patients with ACL tears. This meta-analysis included all studies comparing isokinetic thigh muscle strengths and hamstring-to-quadriceps ratio in the injured and uninjured legs of patients with ACL tear, without or before surgery. Thirteen studies were included in the meta-analysis. Quadriceps and hamstring strengths were 22.3 N∙m (95% CI: 15.2 to 29.3 N∙m; P<0.001) and 7.4 N∙m (95% CI: 4.3 to 10.5 N∙m; P<0.001) lower, respectively, on the injured than on the uninjured side. The mean hamstring-to-quadriceps ratio was 4% greater in ACL deficient than in uninjured limbs (95% CI: 1.7% to 6.3%; P<0.001). Conclusively, Decreases were observed in both the quadriceps and hamstring muscles of patients with ACL tear, with the decrease in quadriceps strength being 3-fold greater. These uneven reductions slightly increase the hamstring-to-quadriceps ratio in ACL deficient knees.

Influence of Anterior Cruciate Ligament Tear on Thigh Muscle Strength and Hamstring-to-Quadriceps Ratio: A Meta-Analysis

PubMed Central

Ahn, Sung-Eun; Park, Min-Ji; Lee, Dae-Hee

2016-01-01

Theoretical compensation after anterior cruciate ligament (ACL) tear could cause quadriceps weakness and hamstring activation, preventing anterior tibial subluxation and affecting the expected hamstring-to-quadriceps ratio. Although quadriceps weakness often occurs after ACL tears, it remains unclear whether hamstring strength and hamstring-to-quadriceps ratio increase in ACL deficient knees. This meta-analysis compared the isokinetic muscle strength of quadriceps and hamstring muscles, and the hamstring-to-quadriceps ratio, of the injured and injured limbs of patients with ACL tears. This meta-analysis included all studies comparing isokinetic thigh muscle strengths and hamstring-to-quadriceps ratio in the injured and uninjured legs of patients with ACL tear, without or before surgery. Thirteen studies were included in the meta-analysis. Quadriceps and hamstring strengths were 22.3 N∙m (95% CI: 15.2 to 29.3 N∙m; P<0.001) and 7.4 N∙m (95% CI: 4.3 to 10.5 N∙m; P<0.001) lower, respectively, on the injured than on the uninjured side. The mean hamstring-to-quadriceps ratio was 4% greater in ACL deficient than in uninjured limbs (95% CI: 1.7% to 6.3%; P<0.001). Conclusively, Decreases were observed in both the quadriceps and hamstring muscles of patients with ACL tear, with the decrease in quadriceps strength being 3-fold greater. These uneven reductions slightly increase the hamstring-to-quadriceps ratio in ACL deficient knees. PMID:26745808

Posterolateral hip muscle strengthening versus quadriceps strengthening for patellofemoral pain: a comparative control trial.

PubMed

Khayambashi, Khalil; Fallah, Alireza; Movahedi, Ahmadreza; Bagwell, Jennifer; Powers, Christopher

2014-05-01

To compare the efficacy of posterolateral hip muscle strengthening versus quadriceps strengthening in reducing pain and improving health status in persons with patellofemoral pain (PFP). Comparative control trial. Rehabilitation facility. Persons with a diagnosis of PFP (N=36; 18 men, 18 women). Patients were alternately assigned to a posterolateral hip muscle strengthening group (9 men and 9 women) or a quadriceps strengthening group (9 men and 9 women). The posterolateral hip muscle strengthening group performed hip abductor and external rotator strengthening exercises, whereas the quadriceps strengthening group performed quadriceps strengthening exercises (3 times a week for 8wk). Pain (visual analog scale [VAS]) and health status (Western Ontario McMaster Universities Osteoarthritis Index [WOMAC]) were assessed at baseline, postintervention, and 6-month follow-up. Significant improvements in VAS and WOMAC scores were observed in both groups from baseline to postintervention and baseline to 6-month follow-up (P<.001). Improvements in VAS and WOMAC scores in the posterolateral hip exercise group were superior to those in the quadriceps exercise group postintervention and at 6-month follow-up (P<.05). Although both intervention programs resulted in decreased pain and improved function in persons with PFP, outcomes in the posterolateral hip exercise group were superior to the quadriceps exercise group. The superior outcomes obtained in the posterolateral hip exercise group were maintained 6 months postintervention. Copyright © 2014 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

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

PubMed

Ozalp, Ozge; Inal-Ince, Deniz; Calik, Ebru; Vardar-Yagli, Naciye; Saglam, Melda; Savci, Sema; Arikan, Hulya; Bosnak-Guclu, Meral; Coplu, Lutfi

2012-06-11

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. 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. 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). Peripheral muscle endurance, exercise capacity, fatigue and health status were adversely affected by the presence of bronchiectasis. Fatigue was associated with dyspnea and health status

[Amino acid composition of the rat quadriceps femoris muscle after a flight on the Kosmos-936 biosatellite].

PubMed

Vlasova, T F; Miroshnikova, E B; Poliakov, V V; Murugova, T P

1982-01-01

The amino acid composition of the quadriceps muscle of rats flown onboard the biosatellite Cosmos-936 and exposed to the ground-based synchronous control experiment was studied. The weightless rats showed changes in the amino acid concentration in the quadriceps muscle. The centrifuged flight and synchronous rats displayed an accumulation of free amino acids in the above muscle.

Muscular Activity and Fatigue in Lower-Limb and Trunk Muscles during Different Sit-To-Stand Tests.

PubMed

Roldán-Jiménez, Cristina; Bennett, Paul; Cuesta-Vargas, Antonio I

2015-01-01

Sit-to-stand (STS) tests measure the ability to get up from a chair, reproducing an important component of daily living activity. As this functional task is essential for human independence, STS performance has been studied in the past decades using several methods, including electromyography. The aim of this study was to measure muscular activity and fatigue during different repetitions and speeds of STS tasks using surface electromyography in lower-limb and trunk muscles. This cross-sectional study recruited 30 healthy young adults. Average muscle activation, percentage of maximum voluntary contraction, muscle involvement in motion and fatigue were measured using surface electrodes placed on the medial gastrocnemius (MG), biceps femoris (BF), vastus medialis of the quadriceps (QM), the abdominal rectus (AR), erector spinae (ES), rectus femoris (RF), soleus (SO) and the tibialis anterior (TA). Five-repetition STS, 10-repetition STS and 30-second STS variants were performed. MG, BF, QM, ES and RF muscles showed differences in muscle activation, while QM, AR and ES muscles showed significant differences in MVC percentage. Also, significant differences in fatigue were found in QM muscle between different STS tests. There was no statistically significant fatigue in the BF, MG and SO muscles of the leg although there appeared to be a trend of increasing fatigue. These results could be useful in describing the functional movements of the STS test used in rehabilitation programs, notwithstanding that they were measured in healthy young subjects.

Quadriceps Muscle Function After Rehabilitation With Cryotherapy in Patients With Anterior Cruciate Ligament Reconstruction

PubMed Central

Hart, Joseph M.; Kuenze, Christopher M.; Diduch, David R.; Ingersoll, Christopher D.

2014-01-01

Context: Persistent muscle weakness after anterior cruciate ligament (ACL) reconstruction may be due to underlying activation failure and arthrogenic muscle inhibition (AMI). Knee-joint cryotherapy has been shown to improve quadriceps function transiently in those with AMI, thereby providing an opportunity to improve quadriceps muscle activation and strength in patients with a reconstructed ACL. Objective: To compare quadriceps muscle function in patients with a reconstructed ACL who completed a 2-week intervention including daily cryotherapy (ice bag), daily exercises, or both. Design: Cross-sectional study. Setting: Laboratory. Patients or Other Participants: A total of 30 patients with reconstructed ACLs who were at least 6 months post-index surgery and had measurable quadriceps AMI. Intervention(s): The patients attended 4 supervised visits over a 2-week period. They were randomly assigned to receive 20 minutes of knee-joint cryotherapy, 1 hour of therapeutic rehabilitation exercises, or cryotherapy followed by exercises. Main Outcome Measure(s): We measured quadriceps Hoffmann reflex, normalized maximal voluntary isometric contraction torque, central activation ratio using the superimposed-burst technique, and patient-reported outcomes before and after the intervention period. Results: After the 2-week intervention period, patients who performed rehabilitation exercises immediately after cryotherapy had higher normalized maximal voluntary isometric contraction torques (P = .002, Cohen d effect size = 1.4) compared with those who received cryotherapy alone (P = .16, d = 0.58) or performed exercise alone (P = .16, d = 0.30). Conclusions: After ACL reconstruction, patients with AMI who performed rehabilitation exercises immediately after cryotherapy experienced greater strength gains than those who performed cryotherapy or exercises alone. PMID:25299442

Heterogeneity in chronic fatigue syndrome: evidence from magnetic resonance spectroscopy of muscle.

PubMed

Lane, R J; Barrett, M C; Taylor, D J; Kemp, G J; Lodi, R

1998-05-01

It has been shown previously that some patients with chronic fatigue syndrome show an abnormal increase in plasma lactate following a short period of moderate exercise, in the sub-anaerobic threshold exercise test (SATET). This cannot be explained satisfactorily by the effects of 'inactivity' or 'deconditioning', and patients with abnormal lactate responses to exercise (SATET +ve) have been found to have significantly fewer Type 1 muscle fibres in quadriceps biopsies than SATET -ve patients. We performed phosphorus magnetic resonance spectroscopy on forearm muscles of 10 SATET +ve patients, 9 SATET -ve patients and 13 sedentary volunteers. There were no differences in resting spectra between these groups but at the end of exercise, intracellular pH in the SATET +ve patients was significantly lower than in both the SATET -ve cases and controls (P < 0.03), and the SATET +ve patients also showed a significantly lower ATP synthesis rate during recovery (P < 0.01), indicating impaired mitochondrial oxidative phosphorylation. These observations support other evidence which indicates that chronic fatigue syndrome is a heterogeneous disorder, and confirms the view that some chronic fatigue syndrome patients have a peripheral component to their fatigue.

Recruitment order of quadriceps motor units: femoral nerve vs. direct quadriceps stimulation.

PubMed

Rodriguez-Falces, Javier; Place, Nicolas

2013-12-01

To investigate potential differences in the recruitment order of motor units (MUs) in the quadriceps femoris when electrical stimulation is applied over the quadriceps belly versus the femoral nerve. M-waves and mechanical twitches were evoked using femoral nerve stimulation and direct quadriceps stimulation of gradually increasing intensity from 20 young, healthy subjects. Recruitment order was investigated by analysing the time-to-peak twitch and the time interval from the stimulus artefact to the M-wave positive peak (M-wave latency) for the vastus medialis (VM) and vastus lateralis (VL) muscles. During femoral nerve stimulation, time-to-peak twitch and M-wave latency decreased consistently (P < 0.05) with increasing stimulus intensity, whereas, during graded direct quadriceps stimulation, time-to-peak twitch and VL M-wave latency did not show a clear trend (P > 0.05). For the VM muscle, M-wave latency decreased with increasing stimulation level for both femoral nerve and direct quadriceps stimulation, whereas, for the VL muscle, the variation of M-wave latency with stimulus intensity was different for the two stimulation geometries (P < 0.05). Femoral nerve stimulation activated MUs according to the size principle, whereas the recruitment order during direct quadriceps stimulation was more complex, depending ultimately on the architecture of the peripheral nerve and its terminal branches below the stimulating electrodes for each muscle. For the VM, MUs were orderly recruited for both stimulation geometries, whereas, for the VL muscle, MUs were orderly recruited for femoral nerve stimulation, but followed no particular order for direct quadriceps stimulation.

Muscle fibre characteristics and lactate responses to exercise in chronic fatigue syndrome.

PubMed

Lane, R J; Barrett, M C; Woodrow, D; Moss, J; Fletcher, R; Archard, L C

1998-03-01

To examine the proportions of type 1 and type 2 muscle fibres and the degree of muscle fibre atrophy and hypertrophy in patients with chronic fatigue syndrome in relation to lactate responses to exercise, and to determine to what extent any abnormalities found might be due to inactivity. Quadriceps needle muscle biopsies were obtained from 105 patients with chronic fatigue syndrome and the proportions of type 1 and 2 fibres and fibre atrophy and hypertrophy factors were determined from histochemical preparations, using a semiautomated image analysis system. Forty one randomly selected biopsies were also examined by electron microscopy. Lactate responses to exercise were measured in the subanaerobic threshold exercise test (SATET). Inactivity would be expected to result in a shift to type 2 fibre predominance and fibre atrophy, but type 1 predominance (23%) was more common than type 2 predominance (3%), and fibre atrophy was found in only 10.4% of cases. Patients with increased lactate responses to exercise did have significantly fewer type 1 muscle fibres (p<0.043 males, p<0.0003 females), but there was no evidence that this group was less active than the patients with normal lactate responses. No significant ultrastructural abnormalities were found. Muscle histometry in patients with chronic fatigue syndrome generally did not show the changes expected as a result of inactivity. However, patients with abnormal lactate responses to exercise had a significantly lower proportion of mitochondria rich type 1 muscle fibres.

Different fatigue-resistant leg muscles and EMG response during whole-body vibration.

PubMed

Simsek, Deniz

2017-12-01

The purpose of this study was to determine the effects of static whole-body vibration (WBV) on the Electromyograhic (EMG) responses of leg muscles, which are fatigue-resistant in different manner. The study population was divided into two groups according to the values obtained by the Fatigue Index [Group I: Less Fatigue Resistant (LFR), n=11; Group II: More Fatigue Resistant (MFR), n=11]. The repeated electromyographic (EMG) activities of four leg muscles were analyzed the following determinants: (1) frequency (30 Hz, 35 Hz and 40 Hz); (2) stance position (static squat position); (3) amplitude (2 mm and 4 mm) and (4) knee flexion angle (120°), (5) vertical vibration platform. Vibration data were analyzed using Minitab 16 (Minitab Ltd, State College, PA, USA). The significance level was set at p<.05. The study results showed that static WBV stimuli given at different frequencies and amplitudes resulted in a significant increase (p<.05) in compared, the LFR group showed significantly (1) higher rates of quadriceps femoris and hamstring muscle fatigue (p<.05), (2) higher levels of knee extensor and flexor torque (p<.05) and (3) higher percentage increases in EMG activation at higher frequencies (max at 40 Hz) and amplitudes (4 mm) (p<.05). The present study can be used for the optimal prescription of vibration exercise and can serve to guide the development of training programs. Copyright © 2017 Elsevier Ltd. All rights reserved.

Oxidative Stress and COPD: The Impact of Oral Antioxidants on Skeletal Muscle Fatigue

PubMed Central

Rossman, Matthew J.; Groot, H. Jonathan; Van Reese; Zhao, Jia; Amann, Markus; Richardson, Russell S.

2014-01-01

PURPOSE Oxidative stress may contribute to exercise intolerance in patients with chronic obstructive pulmonary disease (COPD). This study sought to determine the effect of an acute oral antioxidant cocktail (AOC: vitamins C, E, and alpha-lipoic acid) on skeletal muscle function during dynamic quadriceps exercise in COPD. METHODS Ten patients with COPD performed knee extensor exercise to exhaustion and isotime trials following either the AOC or placebo (PL). Pre- to post-exercise changes in quadriceps maximal voluntary contractions (MVCs) and potentiated twitch forces (Qtw,pot) quantified quadriceps fatigue. RESULTS Under PL conditions, the plasma electron paramagnetic resonance (EPR) spectroscopy signal was inversely correlated with the forced expiratory volume in one second to forced vital capacity ratio (FEV1/FVC), an index of lung dysfunction (r=−0.61, p=0.02), and MVC force (r=−0.56, p=0.04). AOC consumption increased plasma ascorbate levels (10.1±2.2 to 24.1±3.8 ug/ml, p<0.05) and attenuated the area under the curve of the EPR spectroscopy free radical signal (11.6±3.7 to 4.8±2.2 AU, p<0.05), but did not alter endurance time or quadriceps fatigue. The ability of the AOC to decrease the EPR spectroscopy signal, however, was prominent in those with high basal free radicals (n=5, PL: 19.7±5.8 to AOC: 5.8±4.5 AU, p<0.05) with minimal effects in those with low levels (n=5, PL: 1.6±0.5 to AOC: 3.4±1.1 AU). DISCUSSION These data document a relationship between directly measured free radicals and lung dysfunction, and the ability of the AOC to decrease oxidative stress in COPD. Acute amelioration of free radicals, however, does not appear to impact dynamic quadriceps exercise performance. PMID:23299763

Effects of Wearing a Compression Garment During Night Sleep on Recovery From High-Intensity Eccentric-Concentric Quadriceps Muscle Fatigue.

PubMed

Shimokochi, Yohei; Kuwano, Satoshi; Yamaguchi, Taichi; Abutani, Hiroyuki; Shima, Norihiro

2017-10-01

This study aimed to investigate the effects of wearing a compression garment (CG) during night sleep on muscle fatigue recovery after high-intensity eccentric and concentric knee extensor exercises. Seventeen male college students participated in 2 experimental sessions under CG and non-CG (NCG) wearing conditions. Before night sleep under CG or NCG wearing conditions, the subjects performed a fatiguing protocol consisting of 10 sets of 10 repetitions of maximal isokinetic eccentric and concentric knee extensor contractions, with 30-second rest intervals between the sets. Immediately before and after and 24 hours after the fatiguing protocol, maximum voluntary isometric contraction (MVIC) force for knee extensor muscles was measured; surface electromyographic data from the vastus medialis and rectus femoris were also measured. A 2-way repeated-measure analysis of variance followed by Bonferroni pairwise comparisons were used to analyze the differences in each variable. Paired-sample t-tests were used to analyze the mean differences between the conditions at the same time points for each variable. The MVIC 24 hours after the fatiguing protocol was approximately 10% greater in the CG than in the NCG condition (p = 0.033). Changes in the electromyographic variables over time did not significantly differ between the conditions. Thus, it was concluded that wearing a CG during night sleep may promote localized muscle fatigue recovery but does not influence neurological factors after the fatiguing exercise.

Evaluation of Central and Peripheral Fatigue in the Quadriceps Using Fractal Dimension and Conduction Velocity in Young Females

PubMed Central

Beretta-Piccoli, Matteo; D’Antona, Giuseppe; Barbero, Marco; Fisher, Beth; Dieli-Conwright, Christina M.; Clijsen, Ron; Cescon, Corrado

2015-01-01

Purpose Over the past decade, linear and non-linear surface electromyography descriptors for central and peripheral components of fatigue have been developed. In the current study, we tested fractal dimension (FD) and conduction velocity (CV) as myoelectric descriptors of central and peripheral fatigue, respectively. To this aim, we analyzed FD and CV slopes during sustained fatiguing contractions of the quadriceps femoris in healthy humans. Methods A total of 29 recreationally active women (mean age±standard deviation: 24±4 years) and two female elite athletes (one power athlete, age 24 and one endurance athlete, age 30 years) performed two knee extensions: (1) at 20% maximal voluntary contraction (MVC) for 30 s, and (2) at 60% MVC held until exhaustion. Surface EMG signals were detected from the vastus lateralis and vastus medialis using bidimensional arrays. Results Central and peripheral fatigue were described as decreases in FD and CV, respectively. A positive correlation between FD and CV (R=0.51, p<0.01) was found during the sustained 60% MVC, probably as a result of simultaneous motor unit synchronization and a decrease in muscle fiber CV during the fatiguing task. Conclusions Central and peripheral fatigue can be described as changes in FD and CV, at least in young, healthy women. The significant correlation between FD and CV observed at 60% MVC suggests that a mutual interaction between central and peripheral fatigue can arise during submaximal isometric contractions. PMID:25880369

[Simultaneous Traumatic Rupture of Patellar Ligament and Contralateral Rupture of Quadriceps Femoris Muscle].

PubMed

Hladký, V; Havlas, V

2017-01-01

Our paper presents a unique case of a 64-year-old patient after a fall, treated with oral antidiabetic drugs for type II diabetes mellitus. Following a series of examinations, a bilateral injury was diagnosed - patellar ligament tear on the right side and rupture of quadriceps femoris muscle on the left side. It is a rare injury, complicated by simultaneous involvement of both knee joints. The used therapy consisted of a bilateral surgery followed by gradual verticalisation, first with the support of a walking frame and later with the use of forearm crutches. During the final examination, the patient demonstrated full flexion at both knees, while an extension deficit of approx. 5 degrees was still present on the left side. The right knee X-ray showed a proper position of the patella after the removal of temporary tension band wire. Although the clinical results of operative treatment of both the patellar ligament rupture and rupture of quadriceps femoris muscle are in most cases good, early operative treatment, proper technique and post-operative rehabilitation are a prerequisite for success. Key words: knee injuries, patellar ligament, quadriceps muscle, rupture.

Muscle Activation Profiles and Co-Activation of Quadriceps and Hamstring Muscles around Knee Joint in Indian Primary Osteoarthritis Knee Patients.

PubMed

Sharma, Sanjeev Kumar; Yadav, Shiv Lal; Singh, U; Wadhwa, Sanjay

2017-05-01

Osteoarthritis (OA) of knee is a common joint disease. It is associated with reduced knee joint stability due to impaired quadriceps strength, pain, and an altered joint structure. There is altered muscle activation in knee OA patients, which interferes with normal load distribution around the knee and facilitates disease progression. Our primary aim was to determine activation patterns of the muscles i.e., quadriceps and hamstrings in knee OA patients during walking. We also studied co-activation of muscles around knee joint in primary OA knee patients including directed medial and lateral co-contractions. This observational study was done at Department of Physical Medicine and Rehabilitation, All India Institute of Medical Sciences, New Delhi, India. Fourty-four patients with medial compartment primary knee OA were included in study after satisfying inclusion and exclusion criteria. All the patients were assessed for mean, peak and integrated Root Mean Square (RMS), EMG values, muscle activation patterns and co-activation of muscles around knee joint by surface Electromyography (EMG) analysis of Vastus Medialis Obliques (VMO), Vastus Lateralis (VL), Semitendinosus (SMT) and Biceps Femoris (BF) muscles during gait cycle. The EMG waveform for each muscle was amplitude normalized and time normalized to 100% of gait cycle and plotted on graph. Quantitative variables were assessed for normal distribution and accordingly mean±SD or median (range), as appropriate, was computed. For primary OA knee, mean age 61±5 years, mean weight 63.7±10.1 kg, mean height 153.9±7.2 cm, and mean Body Mass Index (BMI) 26.8±3.0 kg/m 2 was found. The muscle activity of hamstrings (SMT muscle and BF) was increased during midstance, late stance and early swing phase of gait cycle as compared to quadriceps (VMO and VL) muscle activity respectively, suggesting co-contraction of opposing muscles around knee joint. Patients with knee OA walk with increased hamstring muscle activity (during

Muscle Activation Profiles and Co-Activation of Quadriceps and Hamstring Muscles around Knee Joint in Indian Primary Osteoarthritis Knee Patients

PubMed Central

Yadav, Shiv Lal; Singh, U; Wadhwa, Sanjay

2017-01-01

Introduction Osteoarthritis (OA) of knee is a common joint disease. It is associated with reduced knee joint stability due to impaired quadriceps strength, pain, and an altered joint structure. There is altered muscle activation in knee OA patients, which interferes with normal load distribution around the knee and facilitates disease progression. Aim Our primary aim was to determine activation patterns of the muscles i.e., quadriceps and hamstrings in knee OA patients during walking. We also studied co-activation of muscles around knee joint in primary OA knee patients including directed medial and lateral co-contractions. Materials and Methods This observational study was done at Department of Physical Medicine and Rehabilitation, All India Institute of Medical Sciences, New Delhi, India. Fourty-four patients with medial compartment primary knee OA were included in study after satisfying inclusion and exclusion criteria. All the patients were assessed for mean, peak and integrated Root Mean Square (RMS), EMG values, muscle activation patterns and co-activation of muscles around knee joint by surface Electromyography (EMG) analysis of Vastus Medialis Obliques (VMO), Vastus Lateralis (VL), Semitendinosus (SMT) and Biceps Femoris (BF) muscles during gait cycle. The EMG waveform for each muscle was amplitude normalized and time normalized to 100% of gait cycle and plotted on graph. Quantitative variables were assessed for normal distribution and accordingly mean±SD or median (range), as appropriate, was computed. Results For primary OA knee, mean age 61±5 years, mean weight 63.7±10.1 kg, mean height 153.9±7.2 cm, and mean Body Mass Index (BMI) 26.8±3.0 kg/m2 was found. The muscle activity of hamstrings (SMT muscle and BF) was increased during midstance, late stance and early swing phase of gait cycle as compared to quadriceps (VMO and VL) muscle activity respectively, suggesting co-contraction of opposing muscles around knee joint. Conclusion Patients with knee

Electromyographic analysis of a modified maneuver for quadriceps femoris muscle setting with co-contraction of the hamstrings.

PubMed

Nakajima, Masaaki; Kawamura, Kenji; Takeda, Isao

2003-05-01

A "quadriceps femoris muscle setting" is isometric quadriceps femoris exercise which can be widely used in early knee rehabilitation. However this exercise cannot obtain enough co-contraction of the hamstrings. Isolated quadriceps femoris contraction in knee extension imposes severe strain to anterior cruciate ligament. We succeeded in developing a simple training maneuver that is effective in obtaining co-contraction of the hamstrings--a modified maneuver for the quadriceps femoris muscle setting with the contralateral lower limb raised (MQS). In this study, we analyzed the effect of this maneuver by EMG quantification. Twenty-eight healthy young adult men performed sequential trials consisting of normal quadriceps femoris muscle setting (NQS) and MQS. Electromyographic activity was recorded from surface electrodes on the gluteus maximus, vastus medialis, rectus femoris, vastus lateralis, semitendinosus and biceps femoris (long head), and normalized to values derived from maximal isometric trials. The % maximal voluntary isometric contraction (%MVIC) of the vastus medialis, vastus lateralis and rectus femoris did not vary in the each maneuver. However, the %MVIC of the hamstrings varied significantly in the MQS. This study suggests that effective co-contraction of the hamstrings can be obtained in MQS by adjusting the load to the raised lower limb.

Effective therapy of transected quadriceps muscle in rat: Gastric pentadecapeptide BPC 157.

PubMed

Staresinic, Mario; Petrovic, Igor; Novinscak, Tomislav; Jukic, Ivana; Pevec, Damira; Suknaic, Slaven; Kokic, Neven; Batelja, Lovorka; Brcic, Luka; Boban-Blagaic, Alenka; Zoric, Zdenka; Ivanovic, Domagoj; Ajduk, Marko; Sebecic, Bozidar; Patrlj, Leonardo; Sosa, Tomislav; Buljat, Gojko; Anic, Tomislav; Seiwerth, Sven; Sikiric, Predrag

2006-05-01

We report complete transection of major muscle and the systemic peptide treatment that induces healing of quadriceps muscle promptly and then maintains the healing with functional restoration. Initially, stable gastric pentadecapeptide BPC 157 (GEPPPGKPADDAGLV, M.W. 1419, PL-10, PLD-116, PL 14736 Pliva, Croatia; in trials for inflammatory bowel disease; wound treatment; no toxicity reported; effective alone without carrier) also superiorly accelerates the healing of transected Achilles tendon. Regularly, quadriceps muscle completely transected transversely 1.0 cm proximal to patella presents a definitive defect that cannot be compensated in rat. BPC 157 (10 microg, 10 ng, 10 pg/kg) is given intraperitoneally, once daily; the first application 30 min posttransection, the final 24 h before sacrifice. It consistently improves muscle healing throughout the whole 72-day period. Improved are: (i) biomechanic (load of failure increased); (ii) function (walking recovery and extensor postural thrust/motor function index returned toward normal healthy values); (iii) microscopy/immunochemistry [i.e., mostly muscle fibers connect muscle segments; absent gap; significant desmin positivity for ongoing regeneration of muscle; larger myofibril diameters on both sides, distal and proximal (normal healthy rat-values reached)]; (iv) macroscopic presentation (stumps connected; subsequently, atrophy markedly attenuated; finally, presentation close to normal noninjured muscle, no postsurgery leg contracture). Thus, posttransection healing-consistently improved-may suggest this peptide therapeutic application in muscle disorders. Copyright 2006 Orthopaedic Research Society.

The evaluation of muscle recovery after anatomical single-bundle ACL reconstruction using a quadriceps autograft.

PubMed

Iriuchishima, Takanori; Ryu, Keinosuke; Okano, Tatsumasa; Suruga, Makoto; Aizawa, Shin; Fu, Freddie H

2017-05-01

The purpose of this study was to reveal the degree of muscle recovery and report the clinical results of anatomical single-bundle ACL reconstruction using a quadriceps autograft. Twenty subjects undergoing anatomical single-bundle ACL reconstruction using a quadriceps autograft were included in this study. A 5-mm-wide, 8-cm-long graft, involving the entire layer of the quadriceps tendon, was harvested without bone block. The average graft diameter was 8.1 ± 1.4 mm. An initial tension of 30 N was applied. The femoral tunnel was created from the far-medial portal. Each femoral and tibial tunnel was created close to the antero-medial bundle insertion site. For the evaluation of muscle recovery (quadriceps and hamstring), a handheld dynamometer was used. The evaluation of muscle recovery was performed pre-operatively, and at 3, 6, 9, and 12 months after surgery. Muscle recovery data were calculated as a percentage of leg strength in the non-operated leg. Anterior tibial translation (ATT), pivot shift test, and IKDC score were evaluated. The average quadriceps strength pre-operatively, and at 3, 6, 9, and 12 months after ACL reconstruction was 90.5 ± 19, 67.8 ± 21.4, 84 ± 17.5, and 85.1 ± 12.6 %, respectively. The average hamstring strength pre-operatively, and at 3, 6, 9, and 12 months after ACL reconstruction was 99.5 ± 13.7, 78.7 ± 11.4, 90.5 ± 19, and 96.7 ± 13.8 %, respectively. ATT pre-operatively and at 12 months after surgery was 5.4 ± 1.3 and 1.0 ± 0.8 mm, respectively. No subjects exhibited positive pivot shift after surgery. Within 6 months following surgery, quadriceps hypotrophy was observed in all subjects. However, the hypotrophy had recovered at 12 months following surgery. No subjects complained of donor site pain after surgery. Anatomical single-bundle ACL reconstruction using a quadriceps autograft resulted in equivalent level of muscle recovery and knee stability when compared with previously reported ACL

Trunk extensor muscle fatigue influences trunk muscle activities.

PubMed

Hoseinpoor, Tahere Seyed; Kahrizi, Sedighe; Mobini, Bahram

2015-01-01

Trunk muscles fatigue is one of the risk factors in workplaces and daily activities. Loads would be redistributed among active and passive tissues in a non-optimal manner in fatigue conditions. Therefore, a single tissue might be overloaded with minimal loads and as a result the risk of injury would increase. The goal of this paper was to assess the electromyographic response of trunk extensor and abdominal muscles after trunk extensor muscles fatigue induced by cyclic lifting task. This was an experimental study that twenty healthy women participated. For assessing automatic response of trunk extensor and abdominal muscles before and after the fatigue task, electromyographic activities of 6 muscles: thorasic erector spine (TES), lumbar erector spine (LES), lumbar multifidus (LMF), transverse abdominis/ internal oblique (TrA/IO), rectus abdominis (RA) and external oblique (EO) were recorded in standing position with no load and symmetric axial loads equal to 25% of their body weights. Statistical analysis showed that all the abdominal muscles activity decreased with axial loads after performing fatigue task but trunk extensor activity remained constant. Results of the current study indicated that muscle recruitment strategies changed with muscle fatigue and load bearing, therefore risks of tissue injury may increase in fatigue conditions.

Impact of Blood Flow Restriction Exercise on Muscle Fatigue Development and Recovery.

PubMed

Husmann, Florian; Mittlmeier, Thomas; Bruhn, Sven; Zschorlich, Volker; Behrens, Martin

2018-03-01

The present study was designed to provide mechanistic insight into the time course and etiology of muscle fatigue development and recovery during and after low-intensity exercise when it is combined with blood flow restriction (BFR). Seventeen resistance-trained males completed four sets of low-intensity isotonic resistance exercise under two experimental conditions: knee extension exercise (i) with BFR and (ii) without BFR (CON). Neuromuscular tests were performed before, during (immediately after each set of knee extension exercise), and 1, 2, 4, and 8 min after each experimental condition. Maximal voluntary torque, quadriceps twitch torque in response to paired electrical stimuli at 10 Hz (PS10) and 100 Hz (PS100), PS10·PS100 ratio as an index of low-frequency fatigue, and voluntary activation were measured under isometric conditions. Perceptual and EMG data were recorded during each exercise condition. After the first set of exercise, BFR induced significantly greater reductions in maximal voluntary torque, PS100, and PS10·PS100 ratio compared with CON. These parameters progressively declined throughout the BFR protocol but recovered substantially within 2 min postexercise when blood flow was restored. Neither a progressive decline in the course of the exercise protocol nor a substantial recovery of these parameters occurred during and after CON. Only at exercise termination, voluntary activation differed significantly between BFR and CON with greater reductions during BFR. At the early stage of exercise, BFR exacerbated the development of muscle fatigue mainly due to a pronounced impairment in contractile function. Despite the high level of muscle fatigue during BFR exercise, the effect of BFR on muscle fatigue was diminished after 2 min of reperfusion, suggesting that BFR has a strong but short-lasting effect on neuromuscular function.

Contributions of neural excitability and voluntary activation to quadriceps muscle strength following anterior cruciate ligament reconstruction.

PubMed

Lepley, Adam S; Ericksen, Hayley M; Sohn, David H; Pietrosimone, Brian G

2014-06-01

Persistent quadriceps weakness is common following anterior cruciate ligament reconstruction (ACLr). Alterations in spinal-reflexive excitability, corticospinal excitability and voluntary activation have been hypothesized as underlying mechanisms contributing to quadriceps weakness. The aim of this study was to evaluate the predictive capabilities of spinal-reflexive excitability, corticospinal excitability and voluntary activation on quadriceps strength in healthy and ACLr participants. Quadriceps strength was measured using maximal voluntary isometric contractions (MVIC). Voluntary activation was quantified via the central activation ratio (CAR). Corticospinal and spinal-reflexive excitability were measured using active motor thresholds (AMT) and Hoffmann reflexes normalized to maximal muscle responses (H:M), respectively. ACLr individuals were also split into high and low strength subsets based on MVIC. CAR was the only significant predictor in the healthy group. In the ACLr group, CAR and H:M significantly predicted 47% of the variance in MVIC. ACLr individuals in the high strength subset demonstrated significantly higher CAR and H:M than those in the low strength subset. Increased quadriceps voluntary activation, spinal-reflexive excitability and corticospinal excitability relates to increased quadriceps strength in participants following ACLr. Rehabilitation strategies used to target neural alterations may be beneficial for the restoration of muscle strength following ACLr. Copyright © 2014 Elsevier B.V. All rights reserved.

Muscle force compensation among synergistic muscles after fatigue of a single muscle.

PubMed

Stutzig, Norman; Siebert, Tobias

2015-08-01

The aim of this study was to examine control strategies among synergistic muscles after fatigue of a single muscle. It was hypothesized that the compensating mechanism is specific for each fatigued muscle. The soleus (SOL), gastrocnemius lateralis (GL) and medialis (GM) were fatigued in separate sessions on different days. In each experiment, subjects (n = 11) performed maximal voluntary contractions prior to and after fatiguing a single muscle (SOL, GL or GM) while the voluntary muscle activity and torque were measured. Additionally, the maximal single twitch torque of the plantarflexors and the maximal spinal reflex activity (H-reflex) of the SOL, GL and GM were determined. Fatigue was evoked using neuromuscular stimulation. Following fatigue the single twitch torque decreased by -20.1%, -19.5%, and -23.0% when the SOL, GL, or GM, have been fatigued. The maximal voluntary torque did not decrease in any session but the synergistic voluntary muscle activity increased significantly. Moreover, we found no alterations in spinal reflex activity. It is concluded that synergistic muscles compensate each other. Furthermore, it seems that self-compensating mechanism of the fatigued muscles occurred additionally. The force compensation does not depend on the function of the fatigued muscle. Copyright © 2015 Elsevier B.V. All rights reserved.

Effect of quadriceps and hamstrings muscle cooling on standing balance in healthy young men.

PubMed

Alghadir, A H; Anwer, S; Zafar, H; Al-Eisa, E S

2017-09-01

The present study compared the effect of quadriceps and hamstring muscle cooling on standing balance in healthy young men. Thirty healthy young men (18-30 years) participated in the study. The participants were randomly assigned to three groups (n=10 each): quadriceps cooling (QC), hamstring cooling (HC), or control group (no cooling). Participants in the QC and HC groups received 20 minutes of cooling using a cold pack (gel pack), placed on the anterior thigh (from the apex of the patella to the mid-thigh) and the posterior thigh (from the base of the popliteal fossa to the mid-thigh), respectively. Balance score including unilateral stance was measured at baseline and immediately after the application of the cold pack. No significant difference in the balance score was noted in any group after the application of the cold pack (p⟩0.05). Similarly, no significant differences in post-test balance score were noted among the three groups (p⟩0.05). Cooling of the quadriceps and hamstring muscles has no immediate effect on standing balance in healthy young men. However, longitudinal studies are warranted to investigate the long-term effects of cooling these muscles on standing balance.

Quadriceps Contusion

MedlinePlus

... An intramuscular contusion , which is when a muscle tears within the sheath (lining) that surrounds it. An ... the muscle and the sheath surrounding it both tear. Quadriceps contusions are common in sports that involve ...

Influence of patterned electrical neuromuscular stimulation on quadriceps activation in individuals with knee joint injury.

PubMed

Glaviano, Neal R; Langston, William T; Hart, Joseph M; Saliba, Susan

2014-12-01

Neuromuscular Electrical Stimulation is a common intervention to address muscle weakness, however presents with many limitations such as fatigue, muscle damage, and patient discomfort that may influence its effectiveness. One novel form of electrical stimulation purported to improve neuromuscular re-education is Patterned Electrical Neuromuscular Stimulation (PENS), which is proposed to mimic muscle-firing patterns of healthy individuals. PENS provides patterned stimulating to the agonist muscle, antagonist muscle and then agonist muscle again in an effort to replicate firing patterns. The purpose of this study was to determine the effect of a single PENS treatment on knee extension torque and quadriceps activation in individuals with quadriceps inhibition. 18 subjects (10 males and 8 females: 24.2±3.4 years, 175.3±11.8cm, 81.8±12.4kg) with a history of knee injury/pain participated in this double-blinded randomized controlled laboratory trial. Participants demonstrated quadriceps inhibition with a central activation ratio of ≤90%. Maximal voluntary isometric contraction of the quadriceps and central activation ratio were measured before and after treatment. The treatment intervention was a 15-minute patterned electrical stimulation applied to the quadriceps and hamstring muscles with a strong motor contraction or a sham group, who received an identical set up as the PENS group, but received a 1mA subsensory stimulation. A 2×2 (group × time) ANCOVA was used to determine differences in maximal voluntary isometric contraction and central activation ratio between groups. The maximal voluntary isometric contraction was selected as a covariate due to baseline differences. There were no differences in change scores between pre- and post-intervention for maximal voluntary isometric contraction: (PENS: 0.09±0.32Nm/kg and Sham 0.15±0.18Nm/kg, p=0.713), or central activation ratio:(PENS: -1.22±6.06 and Sham: 1.48±3.7, p=0.270). A single Patterned Electrical

Torque decrease during submaximal evoked contractions of the quadriceps muscle is linked not only to muscle fatigue.

PubMed

Matkowski, Boris; Lepers, Romuald; Martin, Alain

2015-05-01

The aim of this study was to analyze the neuromuscular mechanisms involved in the torque decrease induced by submaximal electromyostimulation (EMS) of the quadriceps muscle. It was hypothesized that torque decrease after EMS would reflect the fatigability of the activated motor units (MUs), but also a reduction in the number of MUs recruited as a result of changes in axonal excitability threshold. Two experiments were performed on 20 men to analyze 1) the supramaximal twitch superimposed and evoked at rest during EMS (Experiment 1, n = 9) and 2) the twitch response and torque-frequency relation of the MUs activated by EMS (Experiment 2, n = 11). Torque loss was assessed by 15 EMS-evoked contractions (50 Hz; 6 s on/6 s off), elicited at a constant intensity that evoked 20% of the maximal voluntary contraction (MVC) torque. The same stimulation intensity delivered over the muscles was used to induce the torque-frequency relation and the single electrical pulse evoked after each EMS contraction (Experiment 2). In Experiment 1, supramaximal twitch was induced by femoral nerve stimulation. Torque decreased by ~60% during EMS-evoked contractions and by only ~18% during MVCs. This was accompanied by a rightward shift of the torque-frequency relation of MUs activated and an increase of the ratio between the superimposed and posttetanic maximal twitch evoked during EMS contraction. These findings suggest that the torque decrease observed during submaximal EMS-evoked contractions involved muscular mechanisms but also a reduction in the number of MUs recruited due to changes in axonal excitability. Copyright © 2015 the American Physiological Society.

Normative Quadriceps and Hamstring Muscle Strength Values for Female, Healthy, Elite Handball and Football Players.

PubMed

Risberg, May A; Steffen, Kathrin; Nilstad, Agnethe; Myklebust, Grethe; Kristianslund, Eirik; Moltubakk, Marie M; Krosshaug, Tron

2018-05-23

Risberg, MA, Steffen, K, Nilstad, A, Myklebust, G, Kristianslund, E, Moltubakk, MM, and Krosshaug, T. Normative quadriceps and hamstring muscle strength values for female, healthy, elite handball and football players. J Strength Cond Res XX(X): 000-000, 2018-This study presents normative values for isokinetic knee extension and flexion muscle strength tests in 350 elite, female, handball (n = 150) and football (n = 200) players. Isokinetic concentric muscle strength tests at 60°·sec were recorded bilaterally using a dynamometer. Peak torque (in Newton meter [N·m]), body mass normalized peak torque (N·m·kg), and hamstring to quadriceps ratio (H:Q ratio) for dominant and nondominant legs were recorded. The female elite players were 20.9 ± 4.0 years, started playing at the elite level at the age of 18.2 ± 2.7 years, with a mean of 9.7 ± 2.2 hours of weekly in-season training. Handball players demonstrated greater quadriceps muscle strength compared with football players (11.0%) (p < 0.001), also when normalized to body mass (4.1%) (p = 0.012), but not for weight-adjusted hamstring muscle strength. The H:Q ratio was higher on the dominant compared with the nondominant leg for handball players only (p = 0.012).The H:Q ratio was significantly lower for handball players (0.58) compared with football players (0.60) (p < 0.02). These normative values for isokinetic knee extension and flexion torques of healthy, elite, female handball and football players can be used to set rehabilitation goals for muscle strength after injury and enable comparison with uninjured legs. Significantly greater quadriceps muscle strength was found for handball players compared with football players, also when normalized to body mass.This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be

Muscle fatigue: general understanding and treatment

PubMed Central

Wan, Jing-jing; Qin, Zhen; Wang, Peng-yuan; Sun, Yang; Liu, Xia

2017-01-01

Muscle fatigue is a common complaint in clinical practice. In humans, muscle fatigue can be defined as exercise-induced decrease in the ability to produce force. Here, to provide a general understanding and describe potential therapies for muscle fatigue, we summarize studies on muscle fatigue, including topics such as the sequence of events observed during force production, in vivo fatigue-site evaluation techniques, diagnostic markers and non-specific but effective treatments. PMID:28983090

Effects of pre- or post-exercise low-level laser therapy (830 nm) on skeletal muscle fatigue and biochemical markers of recovery in humans: double-blind placebo-controlled trial.

PubMed

Dos Reis, Filipe Abdalla; da Silva, Baldomero Antonio Kato; Laraia, Erica Martinho Salvador; de Melo, Rhaiza Marques; Silva, Patrícia Henrique; Leal-Junior, Ernesto Cesar Pinto; de Carvalho, Paulo de Tarso Camillo

2014-02-01

The purpose of this study was to investigate the effect of low-level laser therapy (LLLT) before and after exercise on quadriceps muscle performance, and to evaluate the changes in serum lactate and creatine kinase (CK) levels. The study was randomized, double blind, and placebo controlled. A sample of 27 healthy volunteers (male soccer players) were divided into three groups: placebo, pre-fatigue laser, and post-fatigue laser. The experiment was performed in two sessions, with a 1 week interval between them. Subjects performed two sessions of stretching followed by blood collection (measurement of lactate and CK) at baseline and after fatigue of the quadriceps by leg extension. LLLT was applied to the femoral quadriceps muscle using an infrared laser device (830 nm), 0.0028 cm(2) beam area, six 60 mW diodes, energy of 0.6 J per diode (total energy to each limb 25.2 J (50.4 J total), energy density 214.28 J/cm(2), 21.42 W/cm(2) power density, 70 sec per leg. We measured the time to fatigue and number and maximum load (RM) of repetitions tolerated. Number of repetitions and time until fatigue were primary outcomes, secondary outcomes included serum lactate levels (measured before and 5, 10, and 15 min after exercise), and CK levels (measured before and 5 min after exercise). The number of repetitions (p=0.8965), RM (p=0.9915), and duration of fatigue (p=0.8424) were similar among the groups. Post-fatigue laser treatment significantly decreased the serum lactate concentration relative to placebo treatment (p<0.01) and also within the group over time (after 5 min vs. after 10 and 15 min, p<0.05 both). The CK level was lower in the post-fatigue laser group (p<0.01). Laser application either before or after fatigue reduced the post-fatigue concentrations of serum lactate and CK. The results were more pronounced in the post-fatigue laser group.

Ultrasonographic assessment of the quadriceps muscle and femoral cartilage in transtibial amputees using different prostheses.

PubMed

Şahin Onat, Şule; Malas, Fevziye Ünsal; Öztürk, Gökhan Tuna; Akkaya, Nuray; Kara, Murat; Özçakar, Levent

2016-08-01

In patients with lower limb amputations, gait alteration, increased loading on the intact extremity, and use of prosthesis may lead to joint degeneration. To explore the effects of prosthesis type on quadriceps muscle and distal femoral cartilage thicknesses in transtibial amputees. A cross-sectional study. A total of 38 below-knee amputees were enrolled in the study, of which 13 patients were using vacuum system type prosthesis and 25 patients were using silicon liner pin system prosthesis. Patients' femoral cartilage and quadriceps muscle thickness measurements were performed using musculoskeletal ultrasound. When compared with the intact sides, cartilage and rectus femoris, vastus intermedius, and vastus medialis muscle thickness values were significantly decreased on the amputee sides (all p < 0.05). Clinical characteristics and ultrasound measurements were similar between the two groups except the lateral and medial femoral condyle thicknesses, thinner in the silicon liner pin system users (both p < 0.05). The distal femoral cartilage and quadriceps muscle thicknesses were found to be decreased on the amputated sides, and the negative impact on the cartilage seemed to be worse in the silicon liner pin system users. This study might provide another argument as regards the preference of vacuum system type prosthesis to prevent possible knee osteoarthritis due to cartilage thinning in adult transtibial amputees. © The International Society for Prosthetics and Orthotics 2015.

The quadriceps muscle of knee joint modelling Using Hybrid Particle Swarm Optimization-Neural Network (PSO-NN)

NASA Astrophysics Data System (ADS)

Kamaruddin, Saadi Bin Ahmad; Marponga Tolos, Siti; Hee, Pah Chin; Ghani, Nor Azura Md; Ramli, Norazan Mohamed; Nasir, Noorhamizah Binti Mohamed; Ksm Kader, Babul Salam Bin; Saiful Huq, Mohammad

2017-03-01

Neural framework has for quite a while been known for its ability to handle a complex nonlinear system without a logical model and can learn refined nonlinear associations gives. Theoretically, the most surely understood computation to set up the framework is the backpropagation (BP) count which relies on upon the minimization of the mean square error (MSE). However, this algorithm is not totally efficient in the presence of outliers which usually exist in dynamic data. This paper exhibits the modelling of quadriceps muscle model by utilizing counterfeit smart procedures named consolidated backpropagation neural network nonlinear autoregressive (BPNN-NAR) and backpropagation neural network nonlinear autoregressive moving average (BPNN-NARMA) models in view of utilitarian electrical incitement (FES). We adapted particle swarm optimization (PSO) approach to enhance the performance of backpropagation algorithm. In this research, a progression of tests utilizing FES was led. The information that is gotten is utilized to build up the quadriceps muscle model. 934 preparing information, 200 testing and 200 approval information set are utilized as a part of the improvement of muscle model. It was found that both BPNN-NAR and BPNN-NARMA performed well in modelling this type of data. As a conclusion, the neural network time series models performed reasonably efficient for non-linear modelling such as active properties of the quadriceps muscle with one input, namely output namely muscle force.

Quantitative muscle ultrasound and quadriceps strength in patients with post-polio syndrome.

PubMed

Bickerstaffe, Alice; Beelen, Anita; Zwarts, Machiel J; Nollet, Frans; van Dijk, Johannes P

2015-01-01

We investigated whether muscle ultrasound can distinguish muscles affected by post-polio syndrome (PPS) from healthy muscles and whether severity of ultrasound abnormalities is associated with muscle strength. Echo intensity, muscle thickness, and isometric strength of the quadriceps muscles were measured in 48 patients with PPS and 12 healthy controls. Patients with PPS had significantly higher echo intensity and lower muscle thickness than healthy controls. In patients, both echo intensity and muscle thickness were associated independently with muscle strength. A combined measure of echo intensity and muscle thickness was more strongly related to muscle strength than either parameter alone. Quantitative ultrasound distinguishes healthy muscles from those affected by PPS, and measures of muscle quality and quantity are associated with muscle strength. Hence, ultrasound could be a useful tool for assessing disease severity and monitoring changes resulting from disease progression or clinical intervention in patients with PPS. © 2014 Wiley Periodicals, Inc.

Comparison of the Levels of Pro-Inflammatory Cytokines Released in the Vastus Lateralis Muscle of Patients with Fibromyalgia and Healthy Controls during Contractions of the Quadriceps Muscle – A Microdialysis Study

PubMed Central

Christidis, Nikolaos; Ghafouri, Bijar; Larsson, Anette; Palstam, Annie; Mannerkorpi, Kaisa; Bileviciute-Ljungar, Indre; Löfgren, Monika; Bjersing, Jan; Kosek, Eva; Gerdle, Björn; Ernberg, Malin

2015-01-01

Objective Fibromyalgia is associated with central hyperexcitability, but it is suggested that peripheral input is important to maintain central hyperexcitability. The primary aim was to investigate the levels of pro-inflammatory cytokines released in the vastus lateralis muscle during repetitive dynamic contractions of the quadriceps muscle in patients with fibromyalgia and healthy controls. Secondarily, to investigate if the levels of pro-inflammatory cytokines were correlated with pain or fatigue during these repetitive dynamic contractions. Material and Methods 32 women with fibromyalgia and 32 healthy women (controls) participated in a 4 hour microdialysis session, to sample IL-1β, IL-6, IL-8, and TNF from the most painful point of the vastus lateralis muscle before, during and after 20 minutes of repeated dynamic contractions. Pain (visual analogue scale; 0–100) and fatigue Borg’s Rating of Perceived Exertion Scale; 6–20) were assessed before and during the entire microdialysis session. Results The repetitive dynamic contractions increased pain in the patients with fibromyalgia (P < .001) and induced fatigue in both groups (P < .001). Perceived fatigue was significantly higher among patients with fibromyalgia than controls (P < .001). The levels of IL-1β did not change during contractions in either group. The levels of TNF did not change during contractions in patients with fibromyalgia, but increased in controls (P < .001) and were significantly higher compared to patients with fibromyalgia (P = .033). The levels of IL-6 and IL-8 increased in both groups alike during and after contractions (P’s < .001). There were no correlations between pain or fatigue and cytokine levels after contractions. Conclusion There were no differences between patients with fibromyalgia and controls in release of pro-inflammatory cytokines, and no correlations between levels of pro-inflammatory cytokines and pain or fatigue. Thus, this study indicates that IL-1β, IL-6, IL

Assessment of muscle fatigue using electromygraphm sensing

NASA Astrophysics Data System (ADS)

Helmi, Muhammad Hazimin Bin; Ping, Chew Sue; Ishak, Nur Elliza Binti; Saad, Mohd Alimi Bin Mohd; Mokhtar, Anis Shahida Niza Binti

2017-08-01

Muscle fatigue is condition of muscle decline in ability after undergoing any physical activity. Observation of the muscle condition of an athlete during training is crucial to prevent or minimize injury and able to achieve optimum performance in actual competition. The aim of this project is to develop a muscle monitoring system to detect muscle fatigue in swimming athlete. This device is capable to measure muscle stress level of the swimmer and at the same time provide indication of muscle fatigue level to trainer. Electromyography signal was recorded from the muscle movement while practicing the front crawl stroke repetitively. The time domain data was processed to frequency spectra in order to study the effect of muscle fatigue. The results show that the recorded EMG signal is able to sense muscle fatigue.

Scapular kinematic and shoulder muscle activity alterations after serratus anterior muscle fatigue.

PubMed

Umehara, Jun; Kusano, Ken; Nakamura, Masatoshi; Morishita, Katsuyuki; Nishishita, Satoru; Tanaka, Hiroki; Shimizu, Itsuroh; Ichihashi, Noriaki

2018-02-23

Although the serratus anterior muscle has an important role in scapular movement, no study to date has investigated the effect of serratus anterior fatigue on scapular kinematics and shoulder muscle activity. The purpose of this study was to clarify the effect of serratus anterior fatigue on scapular movement and shoulder muscle activity. The study participants were 16 healthy men. Electrical muscle stimulation was used to fatigue the serratus anterior muscle. Shoulder muscle strength and endurance, scapular movement, and muscle activity were measured before and after the fatigue task. The muscle activity of the serratus anterior, upper and lower trapezius, anterior and middle deltoid, and infraspinatus muscles was recorded, and the median power frequency of these muscles was calculated to examine the degree of muscle fatigue. The muscle endurance and median power frequency of the serratus anterior muscle decreased after the fatigue tasks, whereas the muscle activities of the serratus anterior, upper trapezius, and infraspinatus muscles increased. External rotation of the scapula at the shoulder elevated position increased after the fatigue task. Selective serratus anterior fatigue due to electric muscle stimulation decreased the serratus anterior endurance at the flexed shoulder position. Furthermore, the muscle activities of the serratus anterior, upper trapezius, and infraspinatus increased and the scapular external rotation was greater after serratus anterior fatigue. These results suggest that the rotator cuff and scapular muscle compensated to avoid the increase in internal rotation of the scapula caused by the dysfunction of the serratus anterior muscle. Copyright © 2018 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

Effect of Capacitive and Resistive electric transfer on changes in muscle flexibility and lumbopelvic alignment after fatiguing exercise.

PubMed

Yokota, Yuki; Sonoda, Takuya; Tashiro, Yuto; Suzuki, Yusuke; Kajiwara, Yu; Zeidan, Hala; Nakayama, Yasuaki; Kawagoe, Mirei; Shimoura, Kanako; Tatsumi, Masataka; Nakai, Kengo; Nishida, Yuichi; Bito, Tsubasa; Yoshimi, Soyoka; Aoyama, Tomoki

2018-05-01

[Purpose] This study aimed to clarify the effects of Capacitive and Resistive electric transfer (CRet) on changes in muscle flexibility and lumbopelvic alignment after fatiguing exercise. [Subjects and Methods] Twenty-two healthy males were assigned into either the CRet (n=11) or control (n=11) group. Fatiguing exercise and CRet intervention were applied at the quadriceps muscle of the participants' dominant legs. The Ely test, pelvic tilt, lumbar lordosis, and superficial temperature were measured before and after exercise and for 30 minutes after intervention. Statistical analysis was performed using one-way analysis of variance, with Tukey's post-hoc multiple comparison test to clarify within-group changes and Student's t-test to clarify between-group differences. [Results] The Ely test and pelvic tilt were significantly different in both groups after exercise, but there was no difference in the CRet group after intervention. Superficial temperature significantly increased in the CRet group for 30 minutes after intervention, in contrast to after the exercise and intervention in the control group. There was no significant between-group difference at any timepoint, except in superficial temperature. [Conclusion] CRet could effectively improve muscle flexibility and lumbopelvic alignment after fatiguing exercise.

Effect of Capacitive and Resistive electric transfer on changes in muscle flexibility and lumbopelvic alignment after fatiguing exercise

PubMed Central

Yokota, Yuki; Sonoda, Takuya; Tashiro, Yuto; Suzuki, Yusuke; Kajiwara, Yu; Zeidan, Hala; Nakayama, Yasuaki; Kawagoe, Mirei; Shimoura, Kanako; Tatsumi, Masataka; Nakai, Kengo; Nishida, Yuichi; Bito, Tsubasa; Yoshimi, Soyoka; Aoyama, Tomoki

2018-01-01

[Purpose] This study aimed to clarify the effects of Capacitive and Resistive electric transfer (CRet) on changes in muscle flexibility and lumbopelvic alignment after fatiguing exercise. [Subjects and Methods] Twenty-two healthy males were assigned into either the CRet (n=11) or control (n=11) group. Fatiguing exercise and CRet intervention were applied at the quadriceps muscle of the participants’ dominant legs. The Ely test, pelvic tilt, lumbar lordosis, and superficial temperature were measured before and after exercise and for 30 minutes after intervention. Statistical analysis was performed using one-way analysis of variance, with Tukey’s post-hoc multiple comparison test to clarify within-group changes and Student’s t-test to clarify between-group differences. [Results] The Ely test and pelvic tilt were significantly different in both groups after exercise, but there was no difference in the CRet group after intervention. Superficial temperature significantly increased in the CRet group for 30 minutes after intervention, in contrast to after the exercise and intervention in the control group. There was no significant between-group difference at any timepoint, except in superficial temperature. [Conclusion] CRet could effectively improve muscle flexibility and lumbopelvic alignment after fatiguing exercise. PMID:29765189

Pyridostigmine in postpolio syndrome: no decline in fatigue and limited functional improvement

PubMed Central

Horemans, H; Nollet, F; Beelen, A; Drost, G; Stegeman, D; Zwarts, M; Bussmann, J; de Visser, M; Lankhorst, G

2003-01-01

Objectives: To investigate the effect of pyridostigmine on fatigue, physical performance, and muscle function in subjects with postpoliomyelitis syndrome. Methods: 67 subjects with increased fatigue and new weakness in one quadriceps muscle showing neuromuscular transmission defects, were included in a randomised, double blind, placebo controlled trial of 60 mg pyridostigmine four times a day for 14 weeks. Primary outcome was fatigue (on the "energy" category of the Nottingham health profile). Secondary outcomes included two minute walking distance and quadriceps strength and jitter. Motor unit size of the quadriceps was studied as a potential effect modifier. The primary data analysis compared the changes from baseline in the outcomes in the last week of treatment between groups. Results: 31 subjects treated with pyridostigmine and 31 subjects treated with placebo completed the trial. No significant effect of pyridostigmine was found on fatigue. The walking distance improved more in the pyridostigmine group than in the placebo group (by 7.2 m (6.0%); p<0.01). Subgroup analysis showed that a significant improvement in walking performance was only found in subjects with normal sized motor units. Quadriceps strength improved more in the pyridostigmine group than in the placebo group (by 6.7 Nm (7.2%); p = 0.15). No effect of pyridostigmine was found on jitter. Conclusions: Pyridostigmine in the prescribed dose did not reduce fatigue in subjects with postpoliomyelitis syndrome. However, it may have a limited beneficial effect on physical performance, especially in subjects with neuromuscular transmission defects in normal sized motor units. PMID:14638885

Immediate effects of kinesiotaping on quadriceps muscle strength: a single-blind, placebo-controlled crossover trial.

PubMed

Vercelli, Stefano; Sartorio, Francesco; Foti, Calogero; Colletto, Lorenzo; Virton, Domenico; Ronconi, Gianpaolo; Ferriero, Giorgio

2012-07-01

To investigate the immediate effects on maximal muscle strength of kinesiotaping (KT) applied to the dominant quadriceps of healthy subjects. Single-blind, placebo-controlled crossover trial. "Salvatore Maugeri" Foundation. With ethical approval and informed consent, a convenience sample of 36 healthy volunteers were recruited. Two subjects did not complete the sessions and were excluded from the analysis. Subjects were tested across 3 different sessions, randomly receiving 2 experimental KT conditions applied with the aim of enhancing and inhibiting muscle strength and a sham KT application. Quadriceps muscle strength was measured by means of an isokinetic maximal test performed at 60 and 180 degrees per second. Two secondary outcome measures were performed: the single-leg triple hop for distance to measure limb performance and the Global Rating of Change Scale (GRCS) to calculate agreement between KT application and subjective perception of strength. Compared with baseline, none of the 3 taping conditions showed a significant change in muscle strength and performance (all P > 0.05). Effect size was very low under all conditions (≤0.08). Very few subjects showed an individual change greater than the minimal detectable change. Global Rating of Change Scale scores demonstrated low to moderate agreement with the type of KT applied, but some placebo effects were reported independently of condition. Our findings indicated no significant effect in the maximal quadriceps strength immediately after the application of inhibition, facilitation, or sham KT. These results do not support the use of KT applied in this way to change maximal muscle strength in healthy people.

Changes in transverse relaxation time of quadriceps femoris muscles after active recovery exercises with different intensities.

PubMed

Mukaimoto, Takahiro; Semba, Syun; Inoue, Yosuke; Ohno, Makoto

2014-01-01

The purpose of this study was to examine the changes in the metabolic state of quadriceps femoris muscles using transverse relaxation time (T2), measured by muscle functional magnetic resonance (MR) imaging, after inactive or active recovery exercises with different intensities following high-intensity knee-extension exercise. Eight healthy men performed recovery sessions with four different conditions for 20 min after high-intensity knee-extension exercise on separate days. During the recovery session, the participants conducted a light cycle exercise for 20 min using a cycle (50%, 70% and 100% of the lactate threshold (LT), respectively: active recovery), and inactive recovery. The MR images of quadriceps femoris muscles were taken before the trial and after the recovery session every 30 min for 120 min. The percentage changes in T2 for the rectus femoris and vastus medialis muscles after the recovery session in 50% LT and 70% LT were significantly lower than those in either inactive recovery or 100% LT. There were no significant differences in those for vastus lateralis and vastus intermedius muscles among the four trials. The percentage changes in T2 of rectus femoris and vastus medialis muscles after the recovery session in 50% LT and 70% LT decreased to the values before the trial faster than those in either inactive recovery or 100% LT. Those of vastus lateralis and vastus intermedius muscles after the recovery session in 50% LT and 70% LT decreased to the values before the trial faster than those in 100% LT. Although the changes in T2 after active recovery exercises were not uniform in exercised muscles, the results of this study suggest that active recovery exercise with the intensities below LT are more effective to recover the metabolic state of quadriceps femoris muscles after intense exercise than with either intensity at LT or inactive recovery.

Evoked EMG versus Muscle Torque during Fatiguing Functional Electrical Stimulation-Evoked Muscle Contractions and Short-Term Recovery in Individuals with Spinal Cord Injury

PubMed Central

Estigoni, Eduardo H.; Fornusek, Che; Hamzaid, Nur Azah; Hasnan, Nazirah; Smith, Richard M.; Davis, Glen M.

2014-01-01

This study investigated whether the relationship between muscle torque and m-waves remained constant after short recovery periods, between repeated intervals of isometric muscle contractions induced by functional electrical stimulation (FES). Eight subjects with spinal cord injury (SCI) were recruited for the study. All subjects had their quadriceps muscles group stimulated during three sessions of isometric contractions separated by 5 min of recovery. The evoked-electromyographic (eEMG) signals, as well as the produced torque, were synchronously acquired during the contractions and during short FES bursts applied during the recovery intervals. All analysed m-wave variables changed progressively throughout the three contractions, even though the same muscle torque was generated. The peak to peak amplitude (PtpA), and the m-wave area (Area) were significantly increased, while the time between the stimulus artefact and the positive peak (PosT) were substantially reduced when the muscles became fatigued. In addition, all m-wave variables recovered faster and to a greater extent than did torque after the recovery intervals. We concluded that rapid recovery intervals between FES-evoked exercise sessions can radically interfere in the use of m-waves as a proxy for torque estimation in individuals with SCI. This needs to be further investigated, in addition to seeking a better understanding of the mechanisms of muscle fatigue and recovery. PMID:25479324

Evoked EMG versus muscle torque during fatiguing functional electrical stimulation-evoked muscle contractions and short-term recovery in individuals with spinal cord injury.

PubMed

Estigoni, Eduardo H; Fornusek, Che; Hamzaid, Nur Azah; Hasnan, Nazirah; Smith, Richard M; Davis, Glen M

2014-12-03

This study investigated whether the relationship between muscle torque and m-waves remained constant after short recovery periods, between repeated intervals of isometric muscle contractions induced by functional electrical stimulation (FES). Eight subjects with spinal cord injury (SCI) were recruited for the study. All subjects had their quadriceps muscles group stimulated during three sessions of isometric contractions separated by 5 min of recovery. The evoked-electromyographic (eEMG) signals, as well as the produced torque, were synchronously acquired during the contractions and during short FES bursts applied during the recovery intervals. All analysed m-wave variables changed progressively throughout the three contractions, even though the same muscle torque was generated. The peak to peak amplitude (PtpA), and the m-wave area (Area) were significantly increased, while the time between the stimulus artefact and the positive peak (PosT) were substantially reduced when the muscles became fatigued. In addition, all m-wave variables recovered faster and to a greater extent than did torque after the recovery intervals. We concluded that rapid recovery intervals between FES-evoked exercise sessions can radically interfere in the use of m-waves as a proxy for torque estimation in individuals with SCI. This needs to be further investigated, in addition to seeking a better understanding of the mechanisms of muscle fatigue and recovery.

Physical Fatigue, Fitness, and Muscle Function in Patients With Antineutrophil Cytoplasmic Antibody-Associated Vasculitis.

PubMed

McClean, Andrew; Morgan, Matthew D; Basu, Neil; Bosch, Jos A; Nightingale, Peter; Jones, David; Harper, Lorraine

2016-09-01

This study investigated differences in cardiorespiratory fitness, muscular function, perceived exertion, and anxiety/depression between patients and healthy controls (HCs) and assessed which of these variables may account for the fatigue experienced by patients. Fatigue was measured in 48 antineutrophil cytoplasmic antibody-associated vasculitis patients and 41 healthy controls using the Multidimensional Fatigue Inventory (MFI-20), focusing on the physical component. Quality of life, anxiety/depression, and sleep quality were assessed by validated questionnaires. Muscle mass was measured by dual-energy x-ray absorptiometry scan, strength as the maximal voluntary contraction (MVC) force, and endurance as sustained isometric contraction at 50% MVC of the quadriceps. Voluntary activation was assessed by superimposed electrical stimulation. Cardiorespiratory fitness ( ˙Vo2 max and oxygen pulse [O2 pulse]) and perceived exertion (Borg scale) were measured during progressive submaximal exercise. Patients reported elevated physical fatigue scores compared to HCs (patients MFI-20 physical 13 [interquartile range (IQR) 8-16], HCs MFI-20 physical 5.5 [IQR 4-8]; P < 0.001). Muscle mass was the same in both groups, but MVC and time to failure in the endurance test were lower due to reduced voluntary activation in patients. Estimated ˙Vo2 max and O2 pulse were the same in both groups. For the same relative workload, patients reported higher ratings of perceived exertion, which correlated with reports of MFI-20 physical fatigue (R(2)  = 0.2). Depression (R(2)  = 0.6), anxiety (R(2)  = 0.3), and sleep disturbance (R(2)  = 0.3) were all correlated with MFI-20 physical fatigue. These observations suggest that fatigue in patients is of a central rather than peripheral origin, supported by associations of fatigue with heightened perception of exertion, depression, anxiety, and sleep disturbance but normal muscle and cardiorespiratory function. © 2016

Ultrasound-Guided Removal of an Infected Loose Body from the Quadriceps Muscle.

PubMed

Razdan, Rishi N; Dube, Tiffany; Specht, Neil

2008-01-01

We present the case of a 35 year-old male with pain and swelling in his right thigh. By CT and sonography, an abscess was localized to the deep, anteromedial, mid-thigh within the quadriceps muscle, along with a 1.3 cm loose body. The infected loose body was removed under ultrasound guidance without complications.

Muscle fatigue in fibromyalgia is in the brain, not in the muscles: a case-control study of perceived versus objective muscle fatigue.

PubMed

Bandak, Elisabeth; Amris, Kirstine; Bliddal, Henning; Danneskiold-Samsøe, Bente; Henriksen, Marius

2013-06-01

To investigate relationships between perceived and objectively measured muscle fatigue during exhausting muscle contractions in women with fibromyalgia (FM) compared with healthy controls (HC). Women with FM and HC completed an isometric muscle exhaustion task at 90° shoulder abduction. Surface electromyographic (EMG) activity in the deltoid muscle was recorded together with self-reported level of muscle fatigue. 25 participants with FM and 23 HC were included. Average time to exhaustion was 254 s shorter in participants with FM than in HC. Participants with FM did not exhibit the same level of objective signs of muscle fatigue, seen as fewer changes in the EMG activity, as the HC during the exhaustion task. The task did not provoke pain in the HC, while participants with FM reported a doubling of pain. Women with FM had shorter exhaustion times and showed fewer objective signs of muscle fatigue during an exhausting isometric shoulder abduction compared with younger HC. This indicates that perceived muscle fatigue may be of central origin and supports the notion of central nervous dysfunction as basic pathological changes in FM.

Reliability of the Q Force; a mobile instrument for measuring isometric quadriceps muscle strength.

PubMed

Douma, K W; Regterschot, G R H; Krijnen, W P; Slager, G E C; van der Schans, C P; Zijlstra, W

2016-01-01

The ability to generate muscle strength is a pre-requisite for all human movement. Decreased quadriceps muscle strength is frequently observed in older adults and is associated with a decreased performance and activity limitations. To quantify the quadriceps muscle strength and to monitor changes over time, instruments and procedures with a sufficient reliability are needed. The Q Force is an innovative mobile muscle strength measurement instrument suitable to measure in various degrees of extension. Measurements between 110 and 130° extension present the highest values and the most significant increase after training. The objective of this study is to determine the test-retest reliability of muscle strength measurements by the Q Force in older adults in 110° extension. Forty-one healthy older adults, 13 males and 28 females were included in the study. Mean (SD) age was 81.9 (4.89) years. Isometric muscle strength of the Quadriceps muscle was assessed with the Q Force at 110° of knee extension. Participants were measured at two sessions with a three to eight day interval between sessions. To determine relative reliability, the intraclass correlation coefficient (ICC) was calculated. To determine absolute reliability, Bland and Altman Limits of Agreement (LOA) were calculated and t-tests were performed. Relative reliability of the Q Force is good to excellent as all ICC coefficients are higher than 0.75. Generally a large 95 % LOA, reflecting only moderate absolute reliability, is found as exemplified for the peak torque left leg of -18.6 N to 33.8 N and the right leg of -9.2 N to 26.4 N was between 15.7 and 23.6 Newton representing 25.2 % to 39.9 % of the size of the mean. Small systematic differences in mean were found between measurement session 1 and 2. The present study shows that the Q Force has excellent relative test-retest reliability, but limited absolute test-retest reliability. Since the Q Force is relatively cheap and mobile it is suitable for

Mechanisms of quadriceps muscle weakness in knee joint osteoarthritis: the effects of prolonged vibration on torque and muscle activation in osteoarthritic and healthy control subjects.

PubMed

Rice, David A; McNair, Peter J; Lewis, Gwyn N

2011-01-01

A consequence of knee joint osteoarthritis (OA) is an inability to fully activate the quadriceps muscles, a problem termed arthrogenic muscle inhibition (AMI). AMI leads to marked quadriceps weakness that impairs physical function and may hasten disease progression. The purpose of the present study was to determine whether γ-loop dysfunction contributes to AMI in people with knee joint OA. Fifteen subjects with knee joint OA and 15 controls with no history of knee joint pathology participated in this study. Quadriceps and hamstrings peak isometric torque (Nm) and electromyography (EMG) amplitude were collected before and after 20 minutes of 50 Hz vibration applied to the infrapatellar tendon. Between-group differences in pre-vibration torque were analysed using a one-way analysis of covariance, with age, gender and body mass (kg) as the covariates. If the γ-loop is intact, vibration should decrease torque and EMG levels in the target muscle; if dysfunctional, then torque and EMG levels should not change following vibration. One-sample t tests were thus undertaken to analyse whether percentage changes in torque and EMG differed from zero after vibration in each group. In addition, analyses of covariance were utilised to analyse between-group differences in the percentage changes in torque and EMG following vibration. Pre-vibration quadriceps torque was significantly lower in the OA group compared with the control group (P = 0.005). Following tendon vibration, quadriceps torque (P < 0.001) and EMG amplitude (P ≤0.001) decreased significantly in the control group but did not change in the OA group (all P > 0.299). Hamstrings torque and EMG amplitude were unchanged in both groups (all P > 0.204). The vibration-induced changes in quadriceps torque and EMG were significantly different between the OA and control groups (all P < 0.011). No between-group differences were observed for the change in hamstrings torque or EMG (all P > 0.554). γ-loop dysfunction may

Skeletal muscle bioenergetics during all-out exercise: mechanistic insight into the oxygen uptake slow component and neuromuscular fatigue

PubMed Central

Layec, Gwenael; Hureau, Thomas J.; Amann, Markus; Richardson, Russell S.

2017-01-01

Although all-out exercise protocols are commonly used, the physiological mechanisms underlying all-out exercise performance are still unclear, and an in-depth assessment of skeletal muscle bioenergetics is lacking. Therefore, phosphorus magnetic resonance spectroscopy (31P-MRS) was utilized to assess skeletal muscle bioenergetics during a 5-min all-out intermittent isometric knee-extensor protocol in eight healthy men. Metabolic perturbation, adenosine triphosphate (ATP) synthesis rates, ATP cost of contraction, and mitochondrial capacity were determined from intramuscular concentrations of phosphocreatine (PCr), inorganic phosphate (Pi), diprotonated phosphate (H2PO4−), and pH. Peripheral fatigue was determined by exercise-induced alterations in potentiated quadriceps twitch force (Qtw) evoked by supramaximal electrical femoral nerve stimulation. The oxidative ATP synthesis rate (ATPOX) attained and then maintained peak values throughout the protocol, despite an ~63% decrease in quadriceps maximal force production. ThusATPOX normalized to force production (ATPOX gain) significantly increased throughout the exercise (1st min: 0.02 ± 0.01, 5th min: 0.04 ± 0.01 mM·min−1·N−1), as did the ATP cost of contraction (1st min: 0.048 ± 0.019, 5th min: 0.052 ± 0.015 mM·min−1·N−1). Additionally, the pre- to postexercise change in Qtw (−52 ± 26%) was significantly correlated with the exercise-induced change in intramuscular pH (r = 0.75) and H2PO4− concentration (r = 0.77). In conclusion, the all-out exercise protocol utilized in the present study elicited a “slow component-like” increase in intramuscular ATPOX gain as well as a progressive increase in the phosphate cost of contraction. Furthermore, the development of peripheral fatigue was closely related to the perturbation of specific fatigue-inducing intramuscular factors (i.e., pH and H2PO4− concentration). NEW & NOTEWORTHY The physiological mechanisms and skeletal muscle bioenergetics

Skeletal muscle bioenergetics during all-out exercise: mechanistic insight into the oxygen uptake slow component and neuromuscular fatigue.

PubMed

Broxterman, Ryan M; Layec, Gwenael; Hureau, Thomas J; Amann, Markus; Richardson, Russell S

2017-05-01

Although all-out exercise protocols are commonly used, the physiological mechanisms underlying all-out exercise performance are still unclear, and an in-depth assessment of skeletal muscle bioenergetics is lacking. Therefore, phosphorus magnetic resonance spectroscopy ( 31 P-MRS) was utilized to assess skeletal muscle bioenergetics during a 5-min all-out intermittent isometric knee-extensor protocol in eight healthy men. Metabolic perturbation, adenosine triphosphate (ATP) synthesis rates, ATP cost of contraction, and mitochondrial capacity were determined from intramuscular concentrations of phosphocreatine (PCr), inorganic phosphate (P i ), diprotonated phosphate ([Formula: see text]), and pH. Peripheral fatigue was determined by exercise-induced alterations in potentiated quadriceps twitch force (Q tw ) evoked by supramaximal electrical femoral nerve stimulation. The oxidative ATP synthesis rate (ATP OX ) attained and then maintained peak values throughout the protocol, despite an ~63% decrease in quadriceps maximal force production. ThusATP OX normalized to force production (ATP OX gain) significantly increased throughout the exercise (1st min: 0.02 ± 0.01, 5th min: 0.04 ± 0.01 mM·min -1 ·N -1 ), as did the ATP cost of contraction (1st min: 0.048 ± 0.019, 5th min: 0.052 ± 0.015 mM·min -1 ·N -1 ). Additionally, the pre- to postexercise change in Q tw (-52 ± 26%) was significantly correlated with the exercise-induced change in intramuscular pH ( r = 0.75) and [Formula: see text] concentration ( r = 0.77). In conclusion, the all-out exercise protocol utilized in the present study elicited a "slow component-like" increase in intramuscular ATP OX gain as well as a progressive increase in the phosphate cost of contraction. Furthermore, the development of peripheral fatigue was closely related to the perturbation of specific fatigue-inducing intramuscular factors (i.e., pH and [Formula: see text] concentration). NEW & NOTEWORTHY The physiological mechanisms

Effects of combined application of progressive resistance training and Russian electrical stimulation on quadriceps femoris muscle strength in elderly women with knee osteoarthritis.

PubMed

Park, Seong Hoon; Hwangbo, Gak

2015-03-01

[Purpose] The aim of this study was to investigate the effects of combined application of progressive resistance training and Russian electrical stimulation on quadriceps femoris muscle strength in elderly women with osteoarthritis of the knee. [Subjects] Thirty women over 65 years of age diagnosed with knee osteoarthritis participated in the present study. The subjects were randomly assigned to a control group (n=10), a progressive resistance training group (n=10), or a Russian electrical stimulation group (n=10). [Methods] Each group was treated 3 times weekly for 8 weeks, and each session lasted 45 minutes. Muscle strength was assessed by measuring the peak torque of the quadriceps femoris muscle. Outcome measurements were performed at baseline and at the fourth and eighth weeks of the treatment period. [Results] All groups showed significant intragroup differences in the quadriceps femoris muscle peak torque after the treatment intervention. There were significant intergroup differences between the Russian electrical stimulation group and the other groups. [Conclusion] The results of this study suggest that combined application of progressive resistance training and Russian electrical stimulation can be effective in strengthening the quadriceps femoris muscle in elderly women with knee osteoarthritis.

Effect of isometric quadriceps exercise on muscle strength, pain, and function in patients with knee osteoarthritis: a randomized controlled study.

PubMed

Anwer, Shahnawaz; Alghadir, Ahmad

2014-05-01

[Purpose] The aim of present study was to investigate the effects of isometric quadriceps exercise on muscle strength, pain, and function in knee osteoarthritis. [Subjects and Methods] Outpatients (N=42, 21 per group; age range 40-65 years; 13 men and 29 women) with osteoarthritis of the knee participated in the study. The experimental group performed isometric exercises including isometric quadriceps, straight leg raising, and isometric hip adduction exercise 5 days a week for 5 weeks, whereas the control group did not performed any exercise program. The outcome measures or dependent variables selected for this study were pain intensity, isometric quadriceps strength, and knee function. These variables were measured using the Numerical Rating Scale (NRS), strength gauge device, and reduced WOMAC index, respectively. All the measurements were taken at baseline (week 0) and at the end of the trial at week 5. [Results] In between-group comparisons, the maximum isometric quadriceps strength, reduction in pain intensity, and improvement in function in the isometric exercise group at the end of the 5th week were significantly greater than those of the control group (p<0.05). [Conclusion] The 5-week isometric quadriceps exercise program showed beneficial effects on quadriceps muscle strength, pain, and functional disability in patients with osteoarthritis of the knee.

The role of central and peripheral muscle fatigue in postcancer fatigue: a randomized controlled trial.

PubMed

Prinsen, Hetty; van Dijk, Johannes P; Zwarts, Machiel J; Leer, Jan Willem H; Bleijenberg, Gijs; van Laarhoven, Hanneke W M

2015-02-01

Postcancer fatigue is a frequently occurring problem, impairing quality of life. Little is known about (neuro)physiological factors determining postcancer fatigue. It may be hypothesized that postcancer fatigue is characterized by low peripheral muscle fatigue and high central muscle fatigue. The aims of this study were to examine whether central and peripheral muscle fatigue differ between fatigued and non-fatigued cancer survivors and to examine the effect of cognitive behavioral therapy (CBT) on peripheral and central muscle fatigue of fatigued cancer survivors in a randomized controlled trial. Sixteen fatigued patients in the intervention group (CBT) and eight fatigued patients in the waiting list group were successfully assessed at baseline and six months later. Baseline measurements of 20 fatigued patients were compared with 20 non-fatigued patients. A twitch interpolation technique and surface electromyography were applied, respectively, during sustained contraction of the biceps brachii muscle. Muscle fiber conduction velocity (MFCV) and central activation failure (CAF) were not significantly different between fatigued and non-fatigued patients. Change scores of MFCV and CAF were not significantly different between patients in the CBT and waiting list groups. Patients in the CBT group reported a significantly larger decrease in fatigue scores than patients in the waiting list group. Postcancer fatigue is neither characterized by abnormally high central muscle fatigue nor by low peripheral muscle fatigue. These findings suggest a difference in the underlying physiological mechanism of postcancer fatigue vs. other fatigue syndromes. Copyright © 2015 American Academy of Hospice and Palliative Medicine. Published by Elsevier Inc. All rights reserved.

“All talk no torque”- A novel set of metrics to quantify muscle fatigue through isometric dynamometry in Functional Electrical Stimulation (FES) muscle studies

NASA Astrophysics Data System (ADS)

Taylor, M. J.; Fornusek, C.; de Chazal, P.; Ruys, A. J.

2017-10-01

Functional Electrical Stimulation (FES) activates nerves and muscles that have been ravished and rendered paralysed by disease. As such, it is advantageous to study joint torques that arise due to electrical stimulation of muscle, to measure fatigue in an indirect, minimally-invasive way. Dynamometry is one way in which this can be achieved. In this paper, torque data is presented from an FES experiment on quadriceps, using isometric dynamometry to measure torque. A library of fatigue metrics to quantify these data are put forward. These metrics include; start and end torque peaks, percentage changes in torque over time, and maximum and minimum torque period algorithms (MTPA 1 and 2), and associated torque-time plots. It is illustrated, by example, how this novel library of metrics can model fatigue over time. Furthermore, these methods are critiqued by a qualitative assessment and compared against one another for their utility in modelling fatigue. Linear trendlines with coefficients of correlation (R 2) and qualitative descriptions of data are used to achieve this. We find that although arduous, individual peak plots yield the most relevant values upon which fatigue can be assessed. Methods to calculate peaks in data have less of a utility, offset by an order of magnitude of ˜101 in comparison with theoretically expected peak numbers. In light of this, we suggest that future methods would be well-inclined to investigate optimized form of peak analysis.

Impact of pain reported during isometric quadriceps muscle strength testing in people with knee pain: data from the osteoarthritis initiative.

PubMed

Riddle, Daniel L; Stratford, Paul W

2011-10-01

Muscle force testing is one of the more common categories of diagnostic tests used in clinical practice. Clinicians have little evidence to guide interpretations of muscle force tests when pain is elicited during testing. The purpose of this study was to examine the construct validity of isometric quadriceps muscle strength tests by determining whether the relationship between maximal isometric quadriceps muscle strength and functional status was influenced by pain during isometric testing. A cross-sectional design was used. Data from the Osteoarthritis Initiative were used to identify 1,344 people with unilateral knee pain and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain subscale scores of 1 or higher on the involved side. Measurements of maximal isometric quadriceps strength and ratings of pain during isometric testing were collected. Outcome variables were WOMAC physical function subscale, 20-m walk test, 400-m walk test, and a repeated chair stand test. Multiple regression models were used to determine whether pain during testing modified or confounded the relationship between strength and functional status. Pearson r correlations among the isometric quadriceps strength measures and the 4 outcome measures ranged from -.36 (95% confidence interval=-.41, -.31) for repeated chair stands to .36 (95% confidence interval=.31, .41) for the 20-m walk test. In the final analyses, neither effect modification nor confounding was found for the repeated chair stand test, the 20-m walk test, the 400-m walk test, or the WOMAC physical function subscale. Moderate or severe pain during testing was weakly associated with reduced strength, but mild pain was not. The disease spectrum was skewed toward mild or moderate symptoms, and the pain measurement scale used during muscle force testing was not ideal. Given that the spectrum of the sample was skewed toward mild or moderate symptoms and disease, the data suggest that isometric quadriceps muscle

Impact of Pain Reported During Isometric Quadriceps Muscle Strength Testing in People With Knee Pain: Data From the Osteoarthritis Initiative

PubMed Central

Stratford, Paul W.

2011-01-01

Background Muscle force testing is one of the more common categories of diagnostic tests used in clinical practice. Clinicians have little evidence to guide interpretations of muscle force tests when pain is elicited during testing. Objective The purpose of this study was to examine the construct validity of isometric quadriceps muscle strength tests by determining whether the relationship between maximal isometric quadriceps muscle strength and functional status was influenced by pain during isometric testing. Design A cross-sectional design was used. Methods Data from the Osteoarthritis Initiative were used to identify 1,344 people with unilateral knee pain and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain subscale scores of 1 or higher on the involved side. Measurements of maximal isometric quadriceps strength and ratings of pain during isometric testing were collected. Outcome variables were WOMAC physical function subscale, 20-m walk test, 400-m walk test, and a repeated chair stand test. Multiple regression models were used to determine whether pain during testing modified or confounded the relationship between strength and functional status. Results Pearson r correlations among the isometric quadriceps strength measures and the 4 outcome measures ranged from −.36 (95% confidence interval=−.41, −.31) for repeated chair stands to .36 (95% confidence interval=.31, .41) for the 20-m walk test. In the final analyses, neither effect modification nor confounding was found for the repeated chair stand test, the 20-m walk test, the 400-m walk test, or the WOMAC physical function subscale. Moderate or severe pain during testing was weakly associated with reduced strength, but mild pain was not. Limitations The disease spectrum was skewed toward mild or moderate symptoms, and the pain measurement scale used during muscle force testing was not ideal. Conclusions Given that the spectrum of the sample was skewed toward mild or moderate

Assessment of muscle fatigue during biking.

PubMed

Knaflitz, Marco; Molinari, Filippo

2003-03-01

The analysis of the surface myoelectric signal recorded while a muscle is performing a sustained contraction is a valuable tool for assessing the progression of localized fatigue. It is well known that the modifications of the spectral content of the myoelectric signal are mainly related to changes in the interstitial fluid pH, which, in turn, affect the membrane excitability of the active muscle fibers. This paper describes the effects of muscle fatigue on the surface myoelectric signal recorded from three thigh and leg muscles during biking, on a population consisting of 22 young healthy volunteers. The purpose of this study was to obtain normative data relative to an exercise protocol mild enough to be applicable, in the future, to pathological subjects as well. Each subject was asked to exercise 30 min on a cycloergometer at a constant velocity and against a constant torque. While subjects were biking, the surface myoelectric signal was recorded from the rectus femoris, the biceps femoris, and the gastrocnemius muscles. In this study, we considered two different aspects of muscle fatigue: first, the localized muscle fatigue as shown by the decrement of the instantaneous frequency of the myoelectric signal during the exercise; second, the modifications of the muscle ON-OFF timing, which could be explained as a strategy for increasing endurance by modifying the role of different muscles during the exercise. The first aspect was studied by obtaining the spectral characteristics of the signals by means of bilinear time-frequency transforms and by applying an original estimator of the instantaneous frequency of stochastic processes based on cross time-frequency transforms. Our results demonstrated that none of the subjects showed significant signs of localized muscle fatigue, since the decrement of the instantaneous frequency during the exercise was always lower than 5% of its initial value. Muscle ON-OFF timing was obtained by applying to the raw myoelectric signal

Duration Dependent Effect of Static Stretching on Quadriceps and Hamstring Muscle Force.

PubMed

Alizadeh Ebadi, Leyla; Çetin, Ebru

2018-03-13

The aim of this study was to determine the acute effect of static stretching on hamstring and quadriceps muscles' isokinetic strength when applied for various durations to elite athletes, to investigate the effect of different static stretching durations on isokinetic strength, and finally to determine the optimal stretching duration. Fifteen elite male athletes from two different sport branches (10 football and five basketball) participated in this study. Experimental protocol was designed as 17 repetitive static stretching exercises for hamstring and quadriceps muscle groups according to the indicated experimental protocols; ((A) 5 min jogging; (B) 5 min jogging followed by 15 s static stretching; (C) 5 min jogging followed by 30 s static stretching; (D) 5 min jogging, followed by static stretching for 45 s). Immediately after each protocol, an isokinetic strength test consisting of five repetitions at 60°/s speed and 20 repetitions at 180°/s speed was recorded for the right leg by the Isomed 2000 device. Friedman variance analysis test was employed for data analysis. According to the analyzes, it was observed that 5 min jogging and 15 s stretching exercises increased the isokinetic strength, whereas 30 and 45 s stretching exercises caused a decrease.

Disease-Induced Skeletal Muscle Atrophy and Fatigue

PubMed Central

Powers, Scott K.; Lynch, Gordon S.; Murphy, Kate T.; Reid, Michael B.; Zijdewind, Inge

2016-01-01

Numerous health problems including acute critical illness, cancer, diseases associated with chronic inflammation, and neurological disorders often result in skeletal muscle weakness and fatigue. Disease-related muscle atrophy and fatigue is an important clinical problem because acquired skeletal muscle weakness can increase the duration of hospitalization, result in exercise limitation, and contribute to a poor quality of life. Importantly, skeletal muscle atrophy is also associated with increased morbidity and mortality of patients. Therefore, improving our understanding of the mechanism(s) responsible for skeletal muscle weakness and fatigue in patients is a required first step to develop clinical protocols to prevent these skeletal muscle problems. This review will highlight the consequences and potential mechanisms responsible for skeletal muscle atrophy and fatigue in patients suffering from acute critical illness, cancer, chronic inflammatory diseases, and neurological disorders. PMID:27128663

Mechanisms of quadriceps muscle weakness in knee joint osteoarthritis: the effects of prolonged vibration on torque and muscle activation in osteoarthritic and healthy control subjects

PubMed Central

2011-01-01

Introduction A consequence of knee joint osteoarthritis (OA) is an inability to fully activate the quadriceps muscles, a problem termed arthrogenic muscle inhibition (AMI). AMI leads to marked quadriceps weakness that impairs physical function and may hasten disease progression. The purpose of the present study was to determine whether γ-loop dysfunction contributes to AMI in people with knee joint OA. Methods Fifteen subjects with knee joint OA and 15 controls with no history of knee joint pathology participated in this study. Quadriceps and hamstrings peak isometric torque (Nm) and electromyography (EMG) amplitude were collected before and after 20 minutes of 50 Hz vibration applied to the infrapatellar tendon. Between-group differences in pre-vibration torque were analysed using a one-way analysis of covariance, with age, gender and body mass (kg) as the covariates. If the γ-loop is intact, vibration should decrease torque and EMG levels in the target muscle; if dysfunctional, then torque and EMG levels should not change following vibration. One-sample t tests were thus undertaken to analyse whether percentage changes in torque and EMG differed from zero after vibration in each group. In addition, analyses of covariance were utilised to analyse between-group differences in the percentage changes in torque and EMG following vibration. Results Pre-vibration quadriceps torque was significantly lower in the OA group compared with the control group (P = 0.005). Following tendon vibration, quadriceps torque (P < 0.001) and EMG amplitude (P ≤0.001) decreased significantly in the control group but did not change in the OA group (all P > 0.299). Hamstrings torque and EMG amplitude were unchanged in both groups (all P > 0.204). The vibration-induced changes in quadriceps torque and EMG were significantly different between the OA and control groups (all P < 0.011). No between-group differences were observed for the change in hamstrings torque or EMG (all P > 0

Validation of Bedside Ultrasound of Muscle Layer Thickness of the Quadriceps in the Critically Ill Patient (VALIDUM Study).

PubMed

Paris, Michael T; Mourtzakis, Marina; Day, Andrew; Leung, Roger; Watharkar, Snehal; Kozar, Rosemary; Earthman, Carrie; Kuchnia, Adam; Dhaliwal, Rupinder; Moisey, Lesley; Compher, Charlene; Martin, Niels; Nicolo, Michelle; White, Tom; Roosevelt, Hannah; Peterson, Sarah; Heyland, Daren K

2017-02-01

In critically ill patients, muscle atrophy is associated with long-term disability and mortality. Bedside ultrasound may quantify muscle mass, but it has not been validated in the intensive care unit (ICU). Here, we compared ultrasound-based quadriceps muscle layer thickness (QMLT) with precise quantifications of computed tomography (CT)-based muscle cross-sectional area (CSA). Patients ≥18 years old with abdominal CT scans performed for clinical reasons were recruited from 9 ICUs for an ultrasound assessment of the quadriceps. CT scans of the third lumbar vertebra, performed <24 hours before or <72 hours after ICU admission, were analyzed for CSA. Low muscularity was defined as 170 cm 2 for men and 110 cm 2 for women. The ultrasound probe was maximally compressed against the skin and QMLT was measured on 2 sites of each quadriceps <72 hours of the CT scan. Mean CT-derived muscle CSA was 109 ± 25 cm 2 for women and 168 ± 37 cm 2 for men, where 58% of patients exhibited low muscularity; only 2.7% patients were underweight according to body mass index. QMLT was positively correlated with CT CSA ( r = 0.45, P < .001). Based on logistic regression to predict low muscularity, QMLT independently generated a concordance index ( c) of 0.67 ( P < .002), which increased to 0.77 ( P < .001) when age, sex, body mass index, Charlson Comorbidity Index, and admission type (surgical vs medical) were added. Our results suggest that QMLT alone with our current protocol may not accurately identify patients with low muscle mass.

A motor unit-based model of muscle fatigue

PubMed Central

2017-01-01

Muscle fatigue is a temporary decline in the force and power capacity of skeletal muscle resulting from muscle activity. Because control of muscle is realized at the level of the motor unit (MU), it seems important to consider the physiological properties of motor units when attempting to understand and predict muscle fatigue. Therefore, we developed a phenomenological model of motor unit fatigue as a tractable means to predict muscle fatigue for a variety of tasks and to illustrate the individual contractile responses of MUs whose collective action determines the trajectory of changes in muscle force capacity during prolonged activity. An existing MU population model was used to simulate MU firing rates and isometric muscle forces and, to that model, we added fatigue-related changes in MU force, contraction time, and firing rate associated with sustained voluntary contractions. The model accurately estimated endurance times for sustained isometric contractions across a wide range of target levels. In addition, simulations were run for situations that have little experimental precedent to demonstrate the potential utility of the model to predict motor unit fatigue for more complicated, real-world applications. Moreover, the model provided insight into the complex orchestration of MU force contributions during fatigue, that would be unattainable with current experimental approaches. PMID:28574981

Effect of whole body vibration training on quadriceps muscle strength in individuals with knee osteoarthritis: a systematic review and meta-analysis.

PubMed

Anwer, Shahnawaz; Alghadir, Ahmad; Zafar, Hamayun; Al-Eisa, Einas

2016-06-01

Several studies have reported the effects of whole body vibration (WBV) training on muscle strength. This systematic review investigates the current evidence regarding the effects of WBV training on quadriceps muscle strength in individuals with knee osteoarthritis (OA). We searched PubMed, CINAHL, Embase, Scopus, PEDro, and Science citation index for research articles published prior to March 2015 using the keywords whole body vibration, vibration training, strength and vibratory exercise in combination with the Medical Subject Heading 'Osteoarthritis knee'. This meta-analysis was limited to randomized controlled trials published in the English language. The quality of the selected studies was assessed by two independent evaluators using the PEDro scale and criteria given by the International Society of Musculoskeletal and Neuronal Interactions (ISMNI) for reporting WBV intervention studies. The risk of bias was assessed using the Cochrane collaboration's tool for domain-based evaluation. Isokinetic quadriceps muscle strength was calculated for each intervention. Eighteen studies were identified in the search. Of these, four studies met the inclusion criteria. Three of these four studies reached high methodological quality on the PEDro scale. Out of the four studies, only one study found significantly greater quadriceps muscle strength gains following WBV compared to the control group. In three of the four studies that compared a control group performing the same exercise as the WBV groups, no additional effect of WBV on quadriceps muscle strength in individuals with knee OA was indicated. Copyright © 2015 Chartered Society of Physiotherapy. Published by Elsevier Ltd. All rights reserved.

Training Effects of Alternated and Pulsed Currents on the Quadriceps Muscles of Athletes.

PubMed

Oliveira, Pedro; Modesto, Karenina Arrais Guida; Bottaro, Martim; Babault, Nicolas; Durigan, João Luiz Quagliotti

2018-05-22

The aim of the study was to evaluate the effects of 6 weeks training with different neuromuscular electrical stimulation (NMES) currents (medium alternated and low-frequency pulsed current) on muscle architecture and neuromuscular performance of competitive athletes. A double-blind controlled and randomized experimental study was carried out with 33 athletes (22.2±2.6 yrs, 74.7±9.8 kg, 176.8±6.0 cm), divided into 3 groups: mid-frequency current (MF, n=12), pulsed current (PC, n=11) and the control group (CG, n=10). Quadriceps maximal voluntary peak torque (PT) and corresponding vastus lateralis electromyographic activity, evoked torque (PT-NMES), vastus lateralis muscle thickness, fascicle length, pennation angle, and level of discomfort were assessed before and after the interventions. NMES training was performed 3 times per week and consisted of 18 sessions, 15 min/session, 6 s duration in each contraction interspersed with 18 s rest. After the training period, muscle thickness increased in the MF and PC groups (p<0.05). PT-NMES increased only in the PC group (p<0.05). All currents produced similar levels of discomfort (p>0.05). Quadriceps NMES training applied through alternated or pulsed currents produced similar effects in architecture and neuromuscular performance in competitive athletes. © Georg Thieme Verlag KG Stuttgart · New York.

The associations between quadriceps muscle strength, power, and knee joint mechanics in knee osteoarthritis: A cross-sectional study.

PubMed

Murray, Amanda M; Thomas, Abbey C; Armstrong, Charles W; Pietrosimone, Brian G; Tevald, Michael A

2015-12-01

Abnormal knee joint mechanics have been implicated in the pathogenesis and progression of knee osteoarthritis. Deficits in muscle function (i.e., strength and power) may contribute to abnormal knee joint loading. The associations between quadriceps strength, power and knee joint mechanics remain unclear in knee osteoarthritis. Three-dimensional motion analysis was used to collect peak knee joint angles and moments during the first 50% of stance phase of gait in 33 participants with knee osteoarthritis. Quadriceps strength and power were assessed using a knee extension machine. Strength was quantified as the one repetition maximum. Power was quantified as the peak power produced at 40-90% of the one repetition maximum. Quadriceps strength accounted for 15% of the variance in peak knee flexion angle (P=0.016). Quadriceps power accounted for 20-29% of the variance in peak knee flexion angle (P<0.05). Quadriceps power at 90% of one repetition maximum accounted for 9% of the variance in peak knee adduction moment (P=0.05). These data suggest that quadriceps power explains more variance in knee flexion angle and knee adduction moment during gait in knee osteoarthritis than quadriceps strength. Additionally, quadriceps power at multiple loads is associated with knee joint mechanics and therefore should be assessed at a variety of loads. Taken together, these results indicate that quadriceps power may be a potential target for interventions aimed at changing knee joint mechanics in knee osteoarthritis. Copyright © 2015 Elsevier Ltd. All rights reserved.

Inhibition of muscle spindle afferent activity during masseter muscle fatigue in the rat.

PubMed

Brunetti, Orazio; Della Torre, Giovannella; Lucchi, Maria Luisa; Chiocchetti, Roberto; Bortolami, Ruggero; Pettorossi, Vito Enrico

2003-09-01

The influence of muscle fatigue on the jaw-closing muscle spindle activity has been investigated by analyzing: (1) the field potentials evoked in the trigeminal motor nucleus (Vmot) by trigeminal mesencephalic nucleus (Vmes) stimulation, (2) the orthodromic and antidromic responses evoked in the Vmes by stimulation of the peripheral and central axons of the muscle proprioceptive afferents, and (3) the extracellular unitary discharge of masseter muscle spindles recorded in the Vmes. The masseter muscle was fatigued by prolonged tetanic masseter nerve electrical stimulation. Pre- and postsynaptic components of the potentials evoked in the Vmot showed a significant reduction in amplitude following muscle fatigue. Orthodromic and antidromic potentials recorded in the Vmes also showed a similar amplitude decrease. Furthermore, muscle fatigue caused a decrease of the discharge frequency of masseter muscle spindle afferents in most of the examined units. The inhibition of the potential amplitude and discharge frequency was strictly correlated with the extent of muscle fatigue and was mediated by the group III and IV afferent muscle fibers activated by fatigue. In fact, the inhibitory effect was abolished by capsaicin injection in the masseter muscle that provokes selective degeneration of small afferent muscle fibers containing neurokinins. We concluded that fatigue signals originating from the muscle and traveling through capsaicin-sensitive fibers are able to diminish the proprioceptive input by a central presynaptic influence. In the second part of the study, we examined the central projection of the masseter small afferents sensitive to capsaicin at the electron-microscopic level. Fiber degeneration was induced by injecting capsaicin into the masseter muscle. Degenerating terminals were found on the soma and stem process in Vmes and on the dendritic tree of neurons in Vmot. This suggests that small muscle afferents may influence the muscle spindle activity through

Focal vibration of quadriceps muscle enhances leg power and decreases knee joint laxity in female volleyball players.

PubMed

Brunetti, O; Botti, F M; Roscini, M; Brunetti, A; Panichi, R; Filippi, G M; Biscarini, A; Pettorossi, V E

2012-12-01

This double-blind randomized controlled study aims at determining the effect of repeated muscle vibration (rMV) on explosive and reactive leg power and on knee laxity of female volleyball players. Eighteen voluntary volleyball athletes, belonging to the same senior regional level team (age=22.7 ± 3 years, height=180.3 ± 5 cm, mass= 64 ± 4 kg) were assigned to three groups (N.=6) for vibration on contracted quadriceps (VC), vibration on relaxed muscle (VR), and sham vibration (NV), respectively. Intervention consisted in 3 rMV sessions performed in 3 consecutive days. In each session, 100 Hz, 300-500 μm amplitude vibratory stimuli were bilaterally delivered to the quadriceps in three consecutive 10-minutes applications. Explosive and reactive leg power and knee joint laxity were evaluated 1 day before, and 1, 30, and 240 days after intervention. In VC group, explosive and reactive leg power increased respectively by ~16% and ~9% at 1 day, by ~19% and ~11% at 30 days and by ~26% and ~13% at 240 days, concomitantly knee laxity decreased by ~6%, ~15% and ~18% at the same times. These changes were significantly larger than in the other groups, in which leg power increment and knee joint laxity reduction remained close to ~3%, ~5% and ~10% at 1, 30 and 240 days, respectively. Combined bilateral voluntary contraction and rMV of the quadriceps muscles is a short-lasting, non-invasive technique that can significantly and persistently improve muscle performance and knee laxity in volleyball women players.

The relationship between quadriceps muscle force, knee flexion, and anterior cruciate ligament strain in an in vitro simulated jump landing.

PubMed

Withrow, Thomas J; Huston, Laura J; Wojtys, Edward M; Ashton-Miller, James A

2006-02-01

An instrumented cadaveric knee construct was used to quantify the association between impact force, quadriceps force, knee flexion angle, and anterior cruciate ligament relative strain in simulated unipedal jump landings. Anterior cruciate ligament strain will correlate with impact force, quadriceps force, and knee flexion angle. Descriptive laboratory study. Eleven cadaveric knees (age, 70.8 [19.3] years; 5 male; 6 female) were mounted in a custom fixture with the tibia and femur secured to a triaxial load cell. Quadriceps, hamstring, and gastrocnemius muscle forces were simulated using pretensioned steel cables (stiffness, 7 kN/cm), and the quadriceps tendon force was measured using a load cell. Mean strain on the anteromedial bundle of the anterior cruciate ligament was measured using a DVRT. With the knee in 25 degrees of flexion, the construct was vertically loaded by an impact force initially directed 4 cm posterior to the knee joint center. Tibiofemoral kinematics was measured using a 3D optoelectronic tracking system. The increase in anterior cruciate ligament relative strain was proportional to the increase in quadriceps force (r(2) = 0.74; P < .00001) and knee flexion angle (r(2) = 0.88; P < .00001) but was not correlated with the impact force (r(2) = 0.009; P = .08). The increase in knee flexion and quadriceps force during this simulated 1-footed landing strongly influenced the relative strain on the anteromedial bundle of the anterior cruciate ligament. These results suggest that even in the presence of knee flexor muscle forces, the increase in quadriceps force required to prevent the knee from flexing during landing can place the anterior cruciate ligament at risk for large strains.

Biomarkers of peripheral muscle fatigue during exercise

PubMed Central

2012-01-01

Background Biomarkers of peripheral muscle fatigue (BPMFs) are used to offer insights into mechanisms of exhaustion during exercise in order to detect abnormal fatigue or to detect defective metabolic pathways. This review aims at describing recent advances and future perspectives concerning the most important biomarkers of muscle fatigue during exercise. Results BPMFs are classified according to the mechanism of fatigue related to adenosine-triphosphate-metabolism, acidosis, or oxidative-metabolism. Muscle fatigue is also related to an immunological response. impaired calcium handling, disturbances in bioenergetic pathways, and genetic responses. The immunological and genetic response may make the muscle susceptible to fatigue but may not directly cause muscle fatigue. Production of BPMFs is predominantly dependent on the type of exercise. BPMFs need to change as a function of the process being monitored, be stable without appreciable diurnal variations, correlate well with exercise intensity, and be present in detectable amounts in easily accessible biological fluids. The most well-known BPMFs are serum lactate and interleukin-6. The most widely applied clinical application is screening for defective oxidative metabolism in mitochondrial disorders by means of the lactate stress test. The clinical relevance of most other BPMFs, however, is under debate, since they often depend on age, gender, physical fitness, the energy supply during exercise, the type of exercise needed to produce the BPMF, and whether healthy or diseased subjects are investigated. Conclusions Though the role of BPMFs during fatigue is poorly understood, measuring BPMFs under specific, standardised conditions appears to be helpful for assessing biological states or processes during exercise and fatigue. PMID:23136874

Long-Term Muscle Fatigue After Standing Work.

PubMed

Garcia, Maria-Gabriela; Läubli, Thomas; Martin, Bernard J

2015-11-01

The aims of this study were to determine long-term fatigue effects in the lower limbs associated with standing work and to estimate possible age and gender influences. The progressive accumulation of muscle fatigue effects is assumed to lead to musculoskeletal disorders, as fatigue generated by sustained low-level exertions exhibits long-lasting effects. However, these effects have received little attention in the lower limbs. Fourteen men and 12 women from two different age groups simulated standing work for 5 hr including 5-min seated rest breaks and a 30-min lunch. The younger group was also tested in a control day. Muscle fatigue was quantified by electrically induced muscle twitches (muscle twitch force [MTF]), postural stability, and subjective evaluation of discomfort. MTF showed a significant fatigue effect after standing work that persisted beyond 30 min after the end of the workday. MTF was not affected on the control day. The center of pressure displacement speed increased significantly over time after standing work but was also affected on the control day. Subjective evaluations of discomfort indicated a significant increase in perception of fatigue immediately after the end of standing work; however, this perception did not persist 30 min after. Age and gender did not influence fatigue. Objective measures show the long-term effects of muscle fatigue after 5 hr of standing work; however, this fatigue is no longer perceived after 30 min of rest postwork. The present results suggest that occupational activities requiring prolonged standing are likely to contribute to lower-extremity and/or back disorders. © 2015, Human Factors and Ergonomics Society.

N-acetylcysteine inhibits muscle fatigue in humans.

PubMed Central

Reid, M B; Stokić, D S; Koch, S M; Khawli, F A; Leis, A A

1994-01-01

N-acetylcysteine (NAC) is a nonspecific antioxidant that selectively inhibits acute fatigue of rodent skeletal muscle stimulated at low (but not high) tetanic frequencies and that decreases contractile function of unfatigued muscle in a dose-dependent manner. The present experiments test the hypothesis that NAC pretreatment can inhibit acute muscular fatigue in humans. Healthy volunteers were studied on two occasions each. Subjects were pretreated with NAC 150 mg/kg or 5% dextrose in water by intravenous infusion. The subject then sat in a chair with surface electrodes positioned over the motor point of tibialis anterior, an ankle dorsiflexor of mixed-fiber composition. The muscle was stimulated to contract electrically (40-55 mA, 0.2-ms pulses) and force production was measured. Function of the unfatigued muscle was assessed by measuring the forces produced during maximal voluntary contractions (MVC) of ankle dorsiflexor muscle groups and during electrical stimulation of tibialis anterior at 1, 10, 20, 40, 80, and 120 Hz (protocol 1). Fatigue was produced using repetitive tetanic stimulations at 10 Hz (protocol 1) or 40 Hz (protocol 2); intermittent stimulations subsequently were used to monitor recovery from fatigue. The contralateral leg then was studied using the same protocol. Pretreatment with NAC did not alter the function of unfatigued muscle; MVC performance and the force-frequency relationship of tibialis anterior were unchanged. During fatiguing contractions stimulated at 10 Hz, NAC increased force output by approximately 15% (P < 0.0001), an effect that was evident after 3 min of repetitive contraction (P < 0.0125) and persisted throughout the 30-min protocol. NAC had no effect on fatigue induced using 40 Hz stimuli or on recovery from fatigue. N-acetylcysteine pretreatment can improve performance of human limb muscle during fatiguing exercise, suggesting that oxidative stress plays a causal role in the fatigue process and identifying antioxidant

Understanding Muscle Dysfunction in Chronic Fatigue Syndrome

PubMed Central

Rutherford, Gina; Manning, Philip; Newton, Julia L.

2016-01-01

Introduction. Chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) is a debilitating disorder of unknown aetiology, characterised by severe disabling fatigue in the absence of alternative diagnosis. Historically, there has been a tendency to draw psychological explanations for the origin of fatigue; however, this model is at odds with findings that fatigue and accompanying symptoms may be explained by central and peripheral pathophysiological mechanisms, including effects of the immune, oxidative, mitochondrial, and neuronal pathways. For example, patient descriptions of their fatigue regularly cite difficulty in maintaining muscle activity due to perceived lack of energy. This narrative review examined the literature for evidence of biochemical dysfunction in CFS/ME at the skeletal muscle level. Methods. Literature was examined following searches of PUB MED, MEDLINE, and Google Scholar, using key words such as CFS/ME, immune, autoimmune, mitochondria, muscle, and acidosis. Results. Studies show evidence for skeletal muscle biochemical abnormality in CFS/ME patients, particularly in relation to bioenergetic dysfunction. Discussion. Bioenergetic muscle dysfunction is evident in CFS/ME, with a tendency towards an overutilisation of the lactate dehydrogenase pathway following low-level exercise, in addition to slowed acid clearance after exercise. Potentially, these abnormalities may lead to the perception of severe fatigue in CFS/ME. PMID:26998359

Pacing Strategy, Muscle Fatigue, and Technique in 1500-m Speed-Skating and Cycling Time Trials.

PubMed

Stoter, Inge K; MacIntosh, Brian R; Fletcher, Jared R; Pootz, Spencer; Zijdewind, Inge; Hettinga, Florentina J

2016-04-01

To evaluate pacing behavior and peripheral and central contributions to muscle fatigue in 1500-m speed-skating and cycling time trials when a faster or slower start is instructed. Nine speed skaters and 9 cyclists, all competing at regional or national level, performed two 1500-m time trials in their sport. Athletes were instructed to start faster than usual in 1 trial and slower in the other. Mean velocity was measured per 100 m. Blood lactate concentrations were measured. Maximal voluntary contraction (MVC), voluntary activation (VA), and potentiated twitch (PT) of the quadriceps muscles were measured to estimate central and peripheral contributions to muscle fatigue. In speed skating, knee, hip, and trunk angles were measured to evaluate technique. Cyclists showed a more explosive start than speed skaters in the fast-start time trial (cyclists performed first 300 m in 24.70 ± 1.73 s, speed skaters in 26.18 ± 0.79 s). Both trials resulted in reduced MVC (12.0% ± 14.5%), VA (2.4% ± 5.0%), and PT (25.4% ± 15.2%). Blood lactate concentrations after the time trial and the decrease in PT were greater in the fast-start than in the slow-start trial. Speed skaters showed higher trunk angles in the fast-start than in the slow-start trial, while knee angles remained similar. Despite similar instructions, behavioral adaptations in pacing differed between the 2 sports, resulting in equal central and peripheral contributions to muscle fatigue in both sports. This provides evidence for the importance of neurophysiological aspects in the regulation of pacing. It also stresses the notion that optimal pacing needs to be studied sport specifically, and coaches should be aware of this.

Electromyography of the quadriceps in patellofemoral pain with patellar subluxation.

PubMed

Mohr, Karen J; Kvitne, Ronald S; Pink, Marilyn M; Fideler, Bradley; Perry, Jacquelin

2003-10-01

This study compared muscle activity and timing of gait phases during functional activities in 13 subjects with patellofemoral pain associated with lateral subluxation and in 11 subjects with healthy knees. Fine wire electromyography recorded activity in the vastus lateralis and vastus medialis oblique during walking and ascending and descending stairs. Subjects were filmed to divide the activities into phases and determine timing. The vastus medialis oblique and vastus lateralis had similar patterns during all activities. Subjects with patellofemoral pain had significantly increased activity in the vastus medialis oblique and vastus lateralis compared with the healthy subjects during the most demanding phases of the gait cycle, suggesting a generalized quadriceps weakness in the patients with patellofemoral pain. Timing differences were seen in walking and stair ascending with the subjects with patellofemoral pain spending significantly more time in stance compared with the healthy subjects. This may be an attempt to reduce the load on weak quadriceps. These data reflect a generalized quadriceps muscle weakness, rather than the prevailing theory of quadriceps muscle imbalance as an etiology of patellofemoral pain. Therefore, we support the practice of strengthening the entire quadriceps muscle group, rather than attempting to specifically target the vastus medialis oblique.

Effects of local and widespread muscle fatigue on movement timing.

PubMed

Cowley, Jeffrey C; Dingwell, Jonathan B; Gates, Deanna H

2014-12-01

Repetitive movements can cause muscle fatigue, leading to motor reorganization, performance deficits, and/or possible injury. The effects of fatigue may depend on the type of fatigue task employed, however. The purpose of this study was to determine how local fatigue of a specific muscle group versus widespread fatigue of various muscle groups affected the control of movement timing. Twenty healthy subjects performed an upper extremity low-load work task similar to sawing for 5 continuous minutes both before and after completing a protocol that either fatigued all the muscles used in the task (widespread fatigue) or a protocol that selectively fatigued the primary muscles used to execute the pushing stroke of the sawing task (localized fatigue). Subjects were instructed to time their movements with a metronome. Timing error, movement distance, and speed were calculated for each movement. Data were then analyzed using a goal-equivalent manifold approach to quantify changes in goal-relevant and non-goal-relevant variability. We applied detrended fluctuation analysis to each time series to quantify changes in fluctuation dynamics that reflected changes in the control strategies used. After localized fatigue, subjects made shorter, slower movements and exerted greater control over non-goal-relevant variability. After widespread fatigue, subjects exerted less control over non-goal-relevant variability and did not change movement patterns. Thus, localized and widespread muscle fatigue affected movement differently. Local fatigue may reduce the available motor solutions and therefore cause greater movement reorganization than widespread muscle fatigue. Subjects altered their control strategies but continued to achieve the timing goal after both fatigue tasks.

Isometric muscle fatigue of the paravertebral and upper extremity muscles after whiplash injury.

PubMed

Rastovic, Pejana; Gojanovic, Marija Definis; Berberovic, Marina; Pavlovic, Marko; Lesko, Josip; Galic, Gordan; Pandza, Maja

2017-01-01

Whiplash-associated disorders (WAD) result from injury of neck structures that most often occur during traffic accidents as a result of rapid acceleration-deceleration. The dominant symptoms manifest in the musculoskeletal system and include increased fatigue. Because of the frequency of whiplash injuries, a simple, cheap and useful diagnostic tool is needed to differentiate whiplash injury from healthy patients or those faking symptoms. To determine muscle fatigue in patients with whiplash injury in six body positions. Analytical cross-sectional study. Emergency center, university hospital. We studied patients with whiplash injury from vehicular traffic accidents who presented to the emergency center within 6 hours of sustaining the injury. We determined whiplash injury grade according to the Quebec Task Force (QTF) classification and measured isometric muscle endurance in six different body positions. Control subjects for each patient were matched by age, gender and anthropomorphic characteristics. Cut-off values were determined to distinguish patients with whiplash injury from controls and for determination of injury grade . QTF grade, time to muscle fatigue in seconds. From September 2013 to September 2016, we enrolled 75 patients with whiplash injury and 75 matching control subjects. In all six positions, the patients with whiplash injury felt muscle fatigue faster than equivalent controls (P < .05) and the time to onset of muscle fatigue decreased with increasing injury grades in all six positions. Assignment to the patient or control group and to injury grade could be predicted with more than 90% accuracy on the basis of time to muscle fatigue. The most efficient position was the highest injury grade, by which 99.9% of the patients were accurately categorized. Isometric muscle endurance correlated with whiplash injury grade in all six positions (P < .01). Under clinical conditions, muscle endurance and the appearance of isometric muscle fatigue during

Muscle fatigue effects can be anticipated to reproduce a movement kinematics learned without fatigue.

PubMed

Monjo, Florian; Forestier, Nicolas

2016-12-17

Muscle fatigue modifies the gain between motor command magnitude and the mechanical muscular response. In other words, post-fatigue, central drives to the muscles must increase to maintain a particular submaximum mechanical output. In this study, we tested the hypothesis that this modified gain can be predicted by the central nervous system (CNS) during discrete ballistic movements. In two separate experiments, subjects were required to perform shoulder flexions in standing and sitting positions at submaximum target peak accelerations. They were assisted with visual feedback informing them on their performance after each trial. Shoulder flexions were performed before and after fatiguing protocols of the focal muscles. Acceleration signals, focal and postural muscle electromyograms (EMGs) were recorded. The results demonstrated that participants were able to reach with precision the target acceleration during the first movements post-fatigue at the cost of significant increase in focal motor command magnitude. Decreased variance of peak accelerations associated with increased focal command variability was observed post-fatigue. During the standing experiment, postural muscle EMGs revealed that anticipatory postural adjustments (APAs) scaled to focal movement acceleration post-fatigue. All these results support that fatigue effects are taken into account during movement planning. Indeed, given that no feedback could enable participants to adjust acceleration during movement, this capacity to anticipate fatigue effects is the exclusive result of feedforward processes. To account for this prediction capacity, we discuss the role of fatigue-related modifications in sensory inputs from the working muscles. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

Static vs. Dynamic Acute Stretching Effect on Quadriceps Muscle Activity during Soccer Instep Kicking

PubMed Central

Amiri-Khorasani, Mohammadtaghi; Kellis, Eleftherios

2013-01-01

The purpose of this study was to compare the effects of static and dynamic stretching on quadriceps muscle activation during maximal soccer instep kicking. The kicking motion of twelve male college soccer players (body height: 174.66 ± 5.01 cm; body mass: 72.83 ± 4.83 kg; age: 18.83 ± 0.75 years) was captured using six synchronized high-speed infra-red cameras whilst electromyography (EMG) signals from vastus medialis (VM), lateralis (VL) and rectus femoris (RF) were recorded before and after static or dynamic stretching. Analysis of variance designs showed a higher increase in knee extension angular velocity (9.65% vs. −1.45%, p < 0.001), RF (37.5% vs. −8.33%, p < 0.001), VM (12% vs. −12%, p < 0.018), and VL EMG activity (20% vs. −6.67%, p < 0.001) after dynamic stretching exercises. Based on these results, it could be suggested that dynamic stretching is probably more effective in increasing quadriceps muscle activity and knee extension angular velocity during the final swing phase of a maximal soccer instep kick than static stretching. PMID:24511339

Mechanisms of cisplatin-induced muscle atrophy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sakai, Hiroyasu, E-mail: sakai@hoshi.ac.jp; Division of Pharmacy Professional Development and Research, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo 1428501; Sagara, Atsunobu

Fatigue is the most common side effect of chemotherapy. However, the mechanisms of “muscle fatigue” induced by anti-cancer drugs are not fully understood. We therefore investigated the muscle-atrophic effect of cisplatin, a platinum-based anti-cancer drug, in mice. C57BL/6J mice were treated with cisplatin (3 mg/kg, i.p.) or saline for 4 consecutive days. On Day 5, hindlimb and quadriceps muscles were isolated from mice. The loss of body weight and food intake under the administration of cisplatin was the same as those in a dietary restriction (DR) group. Under the present conditions, the administration of cisplatin significantly decreased not only themore » muscle mass of the hindlimb and quadriceps but also the myofiber diameter, compared to those in the DR group. The mRNA expression levels of muscle atrophy F-box (MAFbx), muscle RING finger-1 (MuRF1) and forkhead box O3 (FOXO3) were significantly and further increased by cisplatin treated group, compared to DR. Furthermore, the mRNA levels of myostatin and p21 were significantly upregulated by the administration of cisplatin, compared to DR. On the other hand, the phosphorylation of Akt and FOXO3a, which leads to the blockade of the upregulation of MuRF1 and MAFbx, was significantly and dramatically decreased by cisplatin. These findings suggest that the administration of cisplatin increases atrophic gene expression, and may lead to an imbalance between protein synthesis and protein degradation pathways, which would lead to muscle atrophy. This phenomenon could, at least in part, explain the mechanism of cisplatin-induced muscle fatigue. - Highlights: • Cisplatin decreased mass and myofiber diameter in quadriceps muscle. • The mRNA of MAFbx, MuRF1 and FOXO3 were increased by the cisplatin. • The mRNA of myostatin and p21 were upregulated by cisplatin. • The phosphorylation of Akt and FOXO3a was decreased by cisplatin.« less

Proximal and distal muscle fatigue differentially affect movement coordination

PubMed Central

Cowley, Jeffrey C.

2017-01-01

Muscle fatigue can cause people to change their movement patterns and these changes could contribute to acute or overuse injuries. However, these effects depend on which muscles are fatigued. The purpose of this study was to determine the differential effects of proximal and distal upper extremity muscle fatigue on repetitive movements. Fourteen subjects completed a repetitive ratcheting task before and after a fatigue protocol on separate days. The fatigue protocol either fatigued the proximal (shoulder flexor) or distal (finger flexor) muscles. Pre/Post changes in trunk, shoulder, elbow, and wrist kinematics were compared to determine how proximal and distal fatigue affected multi-joint movement patterns and variability. Proximal fatigue caused a significant increase (7°, p < 0.005) in trunk lean and velocity, reduced humeral elevation (11°, p < 0.005), and increased elbow flexion (4°, p < 0.01). In contrast, distal fatigue caused small but significant changes in trunk angles (2°, p < 0.05), increased velocity of wrench movement relative to the hand (17°/s, p < 0.001), and earlier wrist extension (4%, p < 0.005). Movement variability increased at proximal joints but not distal joints after both fatigue protocols (p < 0.05). Varying movements at proximal joints may help people adapt to fatigue at either proximal or distal joints. The identified differences between proximal and distal muscle fatigue adaptations could facilitate risk assessment of occupational tasks. PMID:28235005

Effects of soluble milk protein or casein supplementation on muscle fatigue following resistance training program: a randomized, double-blind, and placebo-controlled study

PubMed Central

2014-01-01

Background The effects of protein supplementation on muscle thickness, strength and fatigue seem largely dependent on its composition. The current study compared the effects of soluble milk protein, micellar casein, and a placebo on strength and fatigue during and after a resistance training program. Methods Sixty-eight physically active men participated in this randomized controlled trial and underwent 10 weeks of lower-body resistance training. Participants were randomly assigned to the Placebo (PLA), Soluble Milk Protein (SMP, with fast digestion rate) or Micellar Casein (MC, with slow digestion rate) group. During the 10-week training period, participants were instructed to take 30 g of the placebo or protein twice a day, or three times on training days. Tests were performed on quadriceps muscles at inclusion (PRE), after 4 weeks (MID) and after 10 weeks (POST) of training. They included muscle endurance (maximum number of repetitions during leg extensions using 70% of the individual maximal load), fatigue (decrease in muscle power after the endurance test), strength, power and muscle thickness. Results Muscle fatigue was significantly lower (P < 0.05) in the SMP group at MID and POST (-326.8 ± 114.1 W and -296.6 ± 130.1 W, respectively) as compared with PLA (-439.2 ± 153.9 W and -479.2 ± 138.1 W, respectively) and MC (-415.1 ± 165.1 W and -413.7 ± 139.4 W, respectively). Increases in maximal muscle power, strength, endurance and thickness were not statistically different between groups. Conclusions The present study demonstrated that protein composition has a large influence on muscular performance after prolonged resistance training. More specifically, as compared with placebo or micellar casein, soluble milk protein (fast digestible) appeared to significantly reduce muscle fatigue induced by intense resistance exercise. PMID:25057266

Effects of soluble milk protein or casein supplementation on muscle fatigue following resistance training program: a randomized, double-blind, and placebo-controlled study.

PubMed

Babault, Nicolas; Deley, Gaëlle; Le Ruyet, Pascale; Morgan, François; Allaert, François André

2014-01-01

The effects of protein supplementation on muscle thickness, strength and fatigue seem largely dependent on its composition. The current study compared the effects of soluble milk protein, micellar casein, and a placebo on strength and fatigue during and after a resistance training program. Sixty-eight physically active men participated in this randomized controlled trial and underwent 10 weeks of lower-body resistance training. Participants were randomly assigned to the Placebo (PLA), Soluble Milk Protein (SMP, with fast digestion rate) or Micellar Casein (MC, with slow digestion rate) group. During the 10-week training period, participants were instructed to take 30 g of the placebo or protein twice a day, or three times on training days. Tests were performed on quadriceps muscles at inclusion (PRE), after 4 weeks (MID) and after 10 weeks (POST) of training. They included muscle endurance (maximum number of repetitions during leg extensions using 70% of the individual maximal load), fatigue (decrease in muscle power after the endurance test), strength, power and muscle thickness. Muscle fatigue was significantly lower (P < 0.05) in the SMP group at MID and POST (-326.8 ± 114.1 W and -296.6 ± 130.1 W, respectively) as compared with PLA (-439.2 ± 153.9 W and -479.2 ± 138.1 W, respectively) and MC (-415.1 ± 165.1 W and -413.7 ± 139.4 W, respectively). Increases in maximal muscle power, strength, endurance and thickness were not statistically different between groups. The present study demonstrated that protein composition has a large influence on muscular performance after prolonged resistance training. More specifically, as compared with placebo or micellar casein, soluble milk protein (fast digestible) appeared to significantly reduce muscle fatigue induced by intense resistance exercise.

A review of concepts regarding the origin of respiratory muscle fatigue

NASA Astrophysics Data System (ADS)

Kuraszkiewicz, Bożena; Piotrkiewicz, Maria

2011-01-01

In this review, the classification of respiratory muscle fatigue from the perspective of its origin is presented. The fatigue is classified as central or peripheral, and the latter further subdivided into high- and low-frequency fatigue. However, muscle fatigue is a complex process and all three types of fatigue probably occur simultaneously in the overloaded respiratory muscles. The relative importance of each type depends on the duration of respiratory loading and other physiological variables. However, central and high-frequency fatigue resolve rapidly once muscle overload is removed, whereas low-frequency fatigue persists over long time.

Muscle fatigue caused by repeated aerial combat maneuvering exercises.

PubMed

Oksa, J; Hämäläinen, O; Rissanen, S; Salminen, M; Kuronen, P

1999-06-01

Little is known about the development of in-flight muscular fatigue during repeated flights. This study was conducted to evaluate muscular fatigue in different upper body and neck muscles during repeated aerial combat maneuvering exercises. Six pilots volunteered as test subjects. They performed one-to-one dog fight exercise three times (1 pilot, four times) in one day. During the flights, the pilots' electromyographic activity (EMG) was measured from the abdomen, back, neck and lateral neck. The mean muscular strain for each muscle was calculated. Before the first flight and after each flight, the maximal isometric strength of each muscle was measured. The results showed that maximal isometric strength between the first and last measurement decreased in the back, neck (p < 0.05) and lateral neck muscles. While the G-stress remained the same, the muscular strain during exercises increased in every muscle, but was significant only in neck and lateral neck (p < 0.05-0.01). Due to these changes, the fatigue index in the neck and lateral neck muscles was 2.0-2.1, and 1.3-1.4 (1.0 = no fatigue) in the abdomen and back muscles. Repeated aerial combat maneuvering exercises caused fatigue in every muscle studied. The fatigue was greater in the neck area, which may increase the risk for neck injuries, and may reduce mission effectiveness. The fighter pilots' muscular strength and endurance in the neck area are subjected to very high demands, especially if exercises are repeated several times. The recovery of the neck muscles from fatigue after repetitive exercises should receive special attention.

Pain-evoked trunk muscle activity changes during fatigue and DOMS.

PubMed

Larsen, L H; Hirata, R P; Graven-Nielsen, T

2017-05-01

Muscle pain may reorganize trunk muscle activity but interactions with exercise-related muscle fatigue and delayed onset muscle soreness (DOMS) is to be clarified. In 19 healthy participants, the trunk muscle activity during 20 multi-directional unpredictable surface perturbations were recorded after bilateral isotonic saline injections (control) and during unilateral and bilateral hypertonic saline-induced low back pain (LBP) in conditions of back muscle fatigue (Day-1) and DOMS (Day-2). Pain intensity and distribution were assessed by visual analogue scale (VAS) scores and pain drawings. The degree of fatigue and DOMS were assessed by Likert scale scores. Root-mean-square electromyographic (RMS-EMG) signals were recorded post-perturbation from six bilateral trunk muscles and the difference from baseline conditions (Delta-RMS-EMG) was extracted and averaged across abdominal and back muscles. In DOMS, peak VAS scores were higher during bilateral control and bilateral saline-induced pain than fatigue (p < 0.001) and during bilateral compared with unilateral pain (p < 0.001). The saline-induced pain areas were larger during DOMS than fatigue (p < 0.01). In response to surface perturbations during fatigue and DOMS, the back muscle Delta-RMS-EMG increased during bilateral compared with unilateral pain and control injections (p < 0.001) and decreased during unilateral pain compared with control injections (p < 0.04). In DOMS compared with fatigue, the post-perturbation Delta-RMS-EMG in back muscles was higher during bilateral pain and lower during unilateral pain (p < 0.001). The abdominal Delta-RMS-EMG was not significantly affected. Facilitated and attenuated back muscle responses to surface perturbations in bilateral and unilateral LBP, respectively, was more expressed during exercise-induced back muscle soreness compared with fatigue. Back muscle activity decreased during unilateral and increased during bilateral pain after unpredictable surface

Muscle fatigue in the temporal and masseter muscles in patients with temporomandibular dysfunction.

PubMed

Woźniak, Krzysztof; Lipski, Mariusz; Lichota, Damian; Szyszka-Sommerfeld, Liliana

2015-01-01

The aim of this study is to evaluate muscle fatigue in the temporal and masseter muscles in patients with temporomandibular dysfunction (TMD). Two hundred volunteers aged 19.3 to 27.8 years (mean 21.50, SD 0.97) participated in this study. Electromyographical (EMG) recordings were performed using a DAB-Bluetooth Instrument (Zebris Medical GmbH, Germany). Muscle fatigue was evaluated on the basis of a maximum effort test. The test was performed during a 10-second maximum isometric contraction (MVC) of the jaws. An analysis of changes in the mean power frequency of the two pairs of temporal and masseter muscles (MPF%) revealed significant differences in the groups of patients with varying degrees of temporomandibular disorders according to Di (P < 0.0000). The study showed an increase in the muscle fatigue of the temporal and masseter muscles correlated with the intensity of temporomandibular dysfunction symptoms in patients. The use of surface electromyography in assessing muscle fatigue is an excellent diagnostic tool for identifying patients with temporomandibular dysfunction.

Muscle Fatigue in the Temporal and Masseter Muscles in Patients with Temporomandibular Dysfunction

PubMed Central

Woźniak, Krzysztof; Lipski, Mariusz; Lichota, Damian

2015-01-01

The aim of this study is to evaluate muscle fatigue in the temporal and masseter muscles in patients with temporomandibular dysfunction (TMD). Two hundred volunteers aged 19.3 to 27.8 years (mean 21.50, SD 0.97) participated in this study. Electromyographical (EMG) recordings were performed using a DAB-Bluetooth Instrument (Zebris Medical GmbH, Germany). Muscle fatigue was evaluated on the basis of a maximum effort test. The test was performed during a 10-second maximum isometric contraction (MVC) of the jaws. An analysis of changes in the mean power frequency of the two pairs of temporal and masseter muscles (MPF%) revealed significant differences in the groups of patients with varying degrees of temporomandibular disorders according to Di (P < 0.0000). The study showed an increase in the muscle fatigue of the temporal and masseter muscles correlated with the intensity of temporomandibular dysfunction symptoms in patients. The use of surface electromyography in assessing muscle fatigue is an excellent diagnostic tool for identifying patients with temporomandibular dysfunction. PMID:25883949

Changes in Quadriceps Muscle Activity During Sustained Recreational Alpine Skiing

PubMed Central

Kröll, Josef; Müller, Erich; Seifert, John G.; Wakeling, James M.

2011-01-01

During a day of skiing thousands of repeated contractions take place. Previous research on prolonged recreational alpine skiing show that physiological changes occur and hence some level of fatigue is inevitable. In the present paper the effect of prolonged skiing on the recruitment and coordination of the muscle activity was investigated. Six subjects performed 24 standardized runs. Muscle activity during the first two (PREskiing) and the last two (POSTskiing) runs was measured from the vastus lateralis (VL) and rectus femoris (RF) using EMG and quantified using wavelet and principal component analysis. The frequency content of the EMG signal shifted in seven out of eight cases significantly towards lower frequencies with highest effects observed for RF on outside leg. A significant pronounced outside leg loading occurred during POSTskiing and the timing of muscle activity peaks occurred more towards turn completion. Specific EMG frequency changes were observed at certain time points throughout the time windows and not over the whole double turn. It is suggested that general muscular fatigue, where additional specific muscle fibers have to be recruited due to the reduced power output of other fibers did not occur. The EMG frequency decrease and intensity changes for RF and VL are caused by altered timing (coordination) within the turn towards a most likely more uncontrolled skiing technique. Hence, these data provide evidence to suggest recreational skiers alter their skiing technique before a potential change in muscle fiber recruitment occurs. Key points The frequency content of the EMG signal shifted in seven out of eight cases significantly towards lower frequencies with highest effects observed for RF. General muscular fatigue, where additional specific fibers have to be recruited due to the reduced power output of other fibers, did not occur. A modified skiing style towards a less functional and hence more uncontrolled skiing technique seems to be a key

Effects of Acute Fatigue of the Hip Flexor Muscles on Hamstring Muscle Extensibility.

PubMed

Muyor, José M; Arrabal-Campos, Francisco M

2016-12-01

The purpose of the present study was to evaluate the influence of acute fatigue of the hip flexor muscles on scores attained in tests frequently used in literature to measure hamstring muscle extensibility, namely the passive straight leg raise (PSLR), active straight leg raise (ASLR), passive knee extension (PKE), active knee extension (AKE), sit-and-reach (SR) and toe-touch (TT) tests. A total of seventy-five healthy and recreationally active adults voluntarily participated in this study. To reach fatigue, the participants actively lifted their legs alternately as many times as possible. In the passive tests, the results were 7.10 ± 5.21° and 5.68 ± 4.54° higher (p < 0.01) for PSLR and PKE tests, respectively, after acute fatigue. However, in the ASLR test, the results were lower post-fatigue than pre-fatigue (mean difference = -5.30° ± 9.51°; p < 0.01). The AKE, SR and TT tests did not show significant differences between pre- and post-fatigue (p > 0.05). Moderate (r = 0.40) to high (r = 0.97) correlation coefficients were found, which were statistically significant among all the measured flexibility tests both pre- and post-fatigue. In conclusion, the active implication of the hip flexor muscles until reaching fatigue had acute influences on the results of the PSLR, PKE and ASLR tests, but not on the results of the AKE, SR and TT tests. It is recommended to use the AKE test to assess hamstring muscle extensibility in situations where athletes show fatigue in their hip flexor muscles.

Aspects of respiratory muscle fatigue in a mountain ultramarathon race.

PubMed

Wüthrich, Thomas U; Marty, Julia; Kerherve, Hugo; Millet, Guillaume Y; Verges, Samuel; Spengler, Christina M

2015-03-01

Ultramarathon running offers a unique possibility to investigate the mechanisms contributing to the limitation of endurance performance. Investigations of locomotor muscle fatigue show that central fatigue is a major contributor to the loss of strength in the lower limbs after an ultramarathon. In addition, respiratory muscle fatigue is known to limit exercise performance, but only limited data are available on changes in respiratory muscle function after ultramarathon running and it is not known whether the observed impairment is caused by peripheral and/or central fatigue. In 22 experienced ultra-trail runners, we assessed respiratory muscle strength, i.e., maximal voluntary inspiratory and expiratory pressures, mouth twitch pressure (n = 16), and voluntary activation (n = 16) using cervical magnetic stimulation, lung function, and maximal voluntary ventilation before and after a 110-km mountain ultramarathon with 5862 m of positive elevation gain. Both maximal voluntary inspiratory (-16% ± 13%) and expiratory pressures (-21% ± 14%) were significantly reduced after the race. Fatigue of inspiratory muscles likely resulted from substantial peripheral fatigue (reduction in mouth twitch pressure, -19% ± 15%; P < 0.01), as voluntary activation (-3% ± 6%, P = 0.09) only tended to be decreased, suggesting negligible or only mild levels of central fatigue. Forced vital capacity remained unchanged, whereas forced expiratory volume in 1 s, peak inspiratory and expiratory flow rates, and maximal voluntary ventilation were significantly reduced (P < 0.05). Ultraendurance running reduces respiratory muscle strength for inspiratory muscles shown to result from significant peripheral muscle fatigue with only little contribution of central fatigue. This is in contrast to findings in locomotor muscles. Whether this difference between muscle groups results from inherent neuromuscular differences, their specific pattern of loading or other reasons remain to be clarified.

Eight weeks of exercise training increases aerobic capacity and muscle mass and reduces fatigue in patients with cirrhosis.

PubMed

Zenith, Laura; Meena, Neha; Ramadi, Ailar; Yavari, Milad; Harvey, Andrea; Carbonneau, Michelle; Ma, Mang; Abraldes, Juan G; Paterson, Ian; Haykowsky, Mark J; Tandon, Puneeta

2014-11-01

Patients with cirrhosis have reduced exercise tolerance, measured objectively as decreased peak exercise oxygen uptake (peak VO2). Reduced peak VO2 is associated with decreased survival time. The effect of aerobic exercise training on peak VO2 has not been well studied in patients with cirrhosis. We evaluated the safety and efficacy of 8 weeks of supervised exercise on peak VO2, quadriceps muscle thickness, and quality of life. In a prospective pilot study, stable patients (79% male, 57.6 ± 6.7 years old) with Child-Pugh class A or B cirrhosis (mean Model for End-Stage Liver Disease score, 10 ± 2.2) were randomly assigned to groups that received exercise training (n = 9) or usual care (controls, n = 10) at the University of Alberta Hospital in Canada from February through June 2013. Supervised exercise was performed on a cycle ergometer 3 days/week for 8 weeks at 60%-80% of baseline peak VO2. Peak VO2, quadriceps muscle thickness (measured by ultrasound), thigh circumference, answers from Chronic Liver Disease Questionnaires, EQ-visual analogue scales, 6-minute walk distance, and Model for End-Stage Liver Disease scores were evaluated at baseline and at week 8. Analysis of covariance was used to compare variables. At week 8, peak VO2 was 5.3 mL/kg/min higher in the exercise group compared with controls (95% confidence interval, 2.9-7.8; P = .001). Thigh circumference (P = .001), thigh muscle thickness (P = .01), and EQ-visual analogue scale determined self-perceived health status (P = .01) was also significantly higher in the exercise group compared with controls at week 8; fatigue subscores of the Chronic Liver Disease Questionnaires were lower in the exercise group compared with controls (P = .01). No adverse events occurred during cardiopulmonary exercise testing or training. In a controlled prospective pilot trial, 8 weeks of supervised aerobic exercise training increased peak VO2 and muscle mass and reduced fatigue in patients with cirrhosis. No

Fatigue-induced early onset of anticipatory postural adjustments in non-fatigued muscles: support for a centrally mediated adaptation.

PubMed

Strang, Adam J; Berg, William P; Hieronymus, Mathias

2009-08-01

Muscle fatigue has been shown to result in early onset of anticipatory postural adjustments (APAs) relative to those produced in a non-fatigued state. This adaptation is thought to reflect an attempt to preserve postural stability during a focal movement performed in a fatigued state. It remains unclear, however, whether this adaptation is of central (e.g., central nervous system motor command) or peripheral (e.g., muscle contractile properties), origin. One way to confirm that this adaptation is centrally driven is to identify fatigued-induced early APA onsets in non-fatigued muscles. In this study, APAs were obtained using a rapid bilateral reaching maneuver and recorded via surface electromyography before and after conditions of rest (n = 25) or fatigue (n = 25). Fatigue was generated using isokinetic exercise of the right leg. Results showed that fatigue-induced early APA onsets occurred in fatigued and non-fatigued muscles, confirming that fatigue-induced early APA onset is a centrally mediated adaptation.

Effect of time-dependent cryotherapy on redox balance of quadriceps injuries.

PubMed

Silva, Marco Aurélio dos Santos; Carvalho, Taiara Ramos de; Cruz, Amanda Cristina Marques Barros da; Jesus, Lennon Rafael Guedine de; Silva Neto, Larissa Alexsandra da; Trajano, Eduardo Tavares Lima; Bezerra, Frank Silva

2016-02-01

Muscle trauma represents a high number of injuries in professional sport and recreation and may occur through several mechanisms. This study aims at analyzing time-dependent effects of cryotherapy on the redox balance in lesioned quadriceps muscles in F1 mice. Twenty male F1 mice were divided into five groups: (a) animals were not subjected to muscle lesioning or treatment (CTR); (b) quadriceps muscle was lesioned without treatment (L); (c) quadriceps muscle was lesioned and treated with cryotherapy for 5 min (LC5); (d) quadriceps muscle was lesioned and treated with cryotherapy for 20 min (LC20); and quadriceps muscle was lesioned and treated with cryotherapy for 40 min (LC40). The mice were euthanized; the quadriceps muscles were collected and subjected to analyses for levels of protein, hydroperoxides, nitrite, catalase (CAT) activity, oxidized glutathione (GSSG) and reduced glutathione (GSH). Protein levels were reduced in L (-39%; p < 0.05), LC5 (-54%; p < 0.05), LC20 (-40%; p < 0.05) and LC40 (-50%; p < 0.05) compared to CTR. There was an increase in lipid peroxidation in L (158%; p < 0.05), LC5 (300%; p < 0.01), LC20 (292%; p < 0.01) and LC40 (362%; p < 0.01) compared to CTR. We observed a significant increase in CAT activity in L (164%; p < 0.05) and LC5 (193%; p < 0.01) compared to CTR; a significant reduction in GSH in L (-60%; p < 0.05) and LC20 (-61%; p < 0.05) compared to CTR; and a significant increase in GSSG in LC5 (171%; p < 0.05) compared to CTR. In addition, GSH/GSSG was reduced in L (-89%; p < 0.01), LC5 (-95%; p < 0.01), LC20 (-59%; p < 0.05), and LC40 (-82%; p < 0.01) compared to CTR. This study showed that the cryotherapy does not improve the oxidative stress in lesioned muscles. Copyright © 2016 Elsevier Inc. All rights reserved.

Sarcolipin overexpression improves muscle energetics and reduces fatigue

PubMed Central

Sopariwala, Danesh H.; Pant, Meghna; Shaikh, Sana A.; Goonasekera, Sanjeewa A.; Molkentin, Jeffery D.; Weisleder, Noah; Ma, Jianjie; Pan, Zui

2015-01-01

Sarcolipin (SLN) is a regulator of sarcoendoplasmic reticulum calcium ATPase in skeletal muscle. Recent studies using SLN-null mice have identified SLN as a key player in muscle thermogenesis and metabolism. In this study, we exploited a SLN overexpression (SlnOE) mouse model to determine whether increased SLN level affected muscle contractile properties, exercise capacity/fatigue, and metabolic rate in whole animals and isolated muscle. We found that SlnOE mice are more resistant to fatigue and can run significantly longer distances than wild-type (WT). Studies with isolated extensor digitorum longus (EDL) muscles showed that SlnOE EDL produced higher twitch force than WT. The force-frequency curves were not different between WT and SlnOE EDLs, but at lower frequencies the pyruvate-induced potentiation of force was significantly higher in SlnOE EDL. SLN overexpression did not alter the twitch and force-frequency curve in isolated soleus muscle. However, during a 10-min fatigue protocol, both EDL and soleus from SlnOE mice fatigued significantly less than WT muscles. Interestingly, SlnOE muscles showed higher carnitine palmitoyl transferase-1 protein expression, which could enhance fatty acid metabolism. In addition, lactate dehydrogenase expression was higher in SlnOE EDL, suggesting increased glycolytic capacity. We also found an increase in store-operated calcium entry (SOCE) in isolated flexor digitorum brevis fibers of SlnOE compared with WT mice. These data allow us to conclude that increased SLN expression improves skeletal muscle performance during prolonged muscle activity by increasing SOCE and muscle energetics. PMID:25701006

Reduced Radial Displacement of the Gastrocnemius Medialis Muscle After Electrically Elicited Fatigue.

PubMed

Macgregor, Lewis J; Ditroilo, Massimiliano; Smith, Iain J; Fairweather, Malcolm M; Hunter, Angus M

2016-08-01

Assessments of skeletal-muscle functional capacity often necessitate maximal contractile effort, which exacerbates muscle fatigue or injury. Tensiomyography (TMG) has been investigated as a means to assess muscle contractile function after fatigue; however, observations have not been contextualized by concurrent physiological measures. To measure peripheral-fatigue-induced alterations in mechanical and contractile properties of the plantar-flexor muscles through noninvasive TMG concurrently with maximal voluntary contraction (MVC) and passive muscle tension (PMT) to validate TMG as a gauge of peripheral fatigue. Pre- and posttest intervention with control. University laboratory. 21 healthy male volunteers. Subjects' plantar flexors were tested for TMG parameters, along with MVC and PMT, before and after either a 5-min rest period (control) or a 5-min electrical-stimulation intervention (fatigue). Temporal (contraction velocity) and spatial (radial displacement) contractile parameters of the gastrocnemius medialis were recorded through TMG. MVC was measured as an indicator of muscle fatigue, and PMT was measured to assess muscle stiffness. Radial displacement demonstrated a fatigue-associated reduction (3.3 ± 1.2 vs 4.0 ± 1.4 mm, P = .031), while contraction velocity remained unaltered. In addition, MVC significantly declined by 122.6 ± 104 N (P < .001) after stimulation (fatigue). PMT was significantly increased after fatigue (139.8 ± 54.3 vs 111.3 ± 44.6 N, P = .007). TMG successfully detected fatigue, evident from reduced MVC, by displaying impaired muscle displacement accompanied by elevated PMT. TMG could be useful in establishing skeletal-muscle fatigue status without exacerbating the functional decrement of the muscle.

Changes in interhemispheric motor connectivity after muscle fatigue

NASA Astrophysics Data System (ADS)

Peltier, Scott; LaConte, Stephen M.; Niyazov, Dmitriy; Liu, Jing; Sahgal, Vinod; Yue, Guang; Hu, Xiaoping

2005-04-01

Synchronized oscillations in resting state timecourses have been detected in recent fMRI studies. These oscillations are low frequency in nature (< 0.08 Hz), and seem to be a property of symmetric cortices. These fluctuations are important as a potential signal of interest, which could indicate connectivity between functionally related areas of the brain. It has also been shown that the synchronized oscillations decrease in some spontaneous pathological states. Thus, detection of these functional connectivity patterns may help to serve as a gauge of normal brain activity. The cognitive effects of muscle fatigue are not well characterized. Sustained fatigue has the potential to dynamically alter activity in brain networks. In this work, we examined the interhemispheric correlations in the left and right primary motor cortices and how they change with muscle fatigue. Resting-state functional MRI imaging was done before and after a repetitive unilateral fatigue task. We find that the number of significant correlations in the bilateral motor network decreases with fatigue. These results suggest that resting-state interhemispheric motor cortex functional connectivity is affected by muscle fatigue.

Duration Dependent Effect of Static Stretching on Quadriceps and Hamstring Muscle Force

PubMed Central

Çetin, Ebru

2018-01-01

The aim of this study was to determine the acute effect of static stretching on hamstring and quadriceps muscles’ isokinetic strength when applied for various durations to elite athletes, to investigate the effect of different static stretching durations on isokinetic strength, and finally to determine the optimal stretching duration. Fifteen elite male athletes from two different sport branches (10 football and five basketball) participated in this study. Experimental protocol was designed as 17 repetitive static stretching exercises for hamstring and quadriceps muscle groups according to the indicated experimental protocols; ((A) 5 min jogging; (B) 5 min jogging followed by 15 s static stretching; (C) 5 min jogging followed by 30 s static stretching; (D) 5 min jogging, followed by static stretching for 45 s). Immediately after each protocol, an isokinetic strength test consisting of five repetitions at 60°/s speed and 20 repetitions at 180°/s speed was recorded for the right leg by the Isomed 2000 device. Friedman variance analysis test was employed for data analysis. According to the analyzes, it was observed that 5 min jogging and 15 s stretching exercises increased the isokinetic strength, whereas 30 and 45 s stretching exercises caused a decrease.

Characterization of chronic fatigue in patients with sarcoidosis in clinical remission.

PubMed

Korenromp, Ingrid H E; Heijnen, Cobi J; Vogels, Oscar J M; van den Bosch, Jules M M; Grutters, Jan C

2011-08-01

Patients with sarcoidosis frequently complain of fatigue, even when sarcoidosis has come into clinical remission. The primary aim of this study was to assess the severity of fatigue in patients with sarcoidosis in clinical remission and to characterize it according to the international criteria for chronic fatigue syndrome (CFS). Furthermore, we evaluated whether fatigue is associated with depression and anxiety, health status, and patient-reported sleep quality, and we recorded physical activity levels and muscle strength as objective assessments of fatigue. Data on 75 patients with sarcoidosis in clinical remission were obtained by questionnaires (Checklist Individual Strength [CIS], Symptom Checklist-90, Beck Depression Inventory for primary care, Medical Outcomes Study 36-Item Short-Form Health Survey), standardized interview (CFS criteria), sleep diary, accelerometer, and muscle strength tests. Fatigue severity mean score in patients with sarcoidosis in clinical remission was high (CIS fatigue severity 30.5 ± 15.5), and criteria for CFS were met in 47% of fatigued participants. Median time since diagnosis was 9 years. Fatigue was associated with depression (P = .01), anxiety (P = .013), and reduced health status (P < .001). Scores on sleep quality were normal. Physical activity levels were reduced in fatigued participants. Muscle strength, particularly handgrip (P = .006) and quadriceps strength (P < .001), was significantly associated with fatigue. Fatigue in patients with sarcoidosis in clinical remission is a frequent symptom and can be characterized as a severe and long-lasting problem, symptomatically similar to CFS. Psychologic distress and reduced health status are associated with fatigue. Interestingly, we observed significantly reduced physical activity and muscle weakness in fatigued patients.

Quadriceps muscle blood flow and oxygen availability during repetitive bouts of isometric exercise in simulated sailing.

PubMed

Vogiatzis, Ioannis; Andrianopoulos, Vasileios; Louvaris, Zafeiris; Cherouveim, Evgenia; Spetsioti, Stavroula; Vasilopoulou, Maroula; Athanasopoulos, Dimitrios

2011-07-01

In this study, we wished to determine whether the observed reduction in quadriceps muscle oxygen availability, reported during repetitive bouts of isometric exercise in simulated sailing efforts (i.e. hiking), is because of restricted muscle blood flow. Six national-squad Laser sailors initially performed three successive 3-min hiking bouts followed by three successive 3-min cycling tests sustained at constant intensities reproducing the cardiac output recorded during each of the three hiking bouts. The blood flow index (BFI) was determined from assessment of the vastus lateralis using near-infrared spectroscopy in association with the light-absorbing tracer indocyanine green dye, while cardiac output was determined from impedance cardiography. At equivalent cardiac outputs (ranging from 10.3±0.5 to 14.8±0.86 L · min(-1)), the increase from baseline in vastus lateralis BFI across the three hiking bouts (from 1.1±0.2 to 3.1±0.6 nM · s(-1)) was lower (P = 0.036) than that seen during the three cycling bouts (from 1.1±0.2 to 7.2±1.4 nM · s(-1)) (Cohen's d: 3.80 nM · s(-1)), whereas the increase from baseline in deoxygenated haemoglobin (by ∼17.0±2.9 μM) (an index of tissue oxygen extraction) was greater (P = 0.006) during hiking than cycling (by ∼5.3±2.7 μM) (Cohen's d: 4.17 μM). The results suggest that reduced vastus lateralis muscle oxygen availability during hiking arises from restricted muscle blood flow in the isometrically acting quadriceps muscles.

Higher Protein Intake Is Associated with Higher Lean Mass and Quadriceps Muscle Strength in Adult Men and Women.

PubMed

Sahni, Shivani; Mangano, Kelsey M; Hannan, Marian T; Kiel, Douglas P; McLean, Robert R

2015-07-01

The impact of dietary protein intake on lower extremity lean mass and strength in community-dwelling adult Americans is not fully understood. The objective was to determine the associations between total protein (TP), animal protein (AP), and plant protein (PP) intakes and lean mass of the legs and quadriceps muscle strength. We further examined whether the associations with quadriceps strength may be explained by lean mass of the legs. This cross-sectional study included men (n = 1166) and women (n = 1509) from the Framingham Offspring Cohort in Massachusetts. Protein intake in grams per day was measured in either 1995-1998 or 1998-2001. Leg lean mass and isometric quadriceps strength, both in kilograms, were measured in 1996-2001. Multilinear regression models estimated adjusted least squares means of each of the muscle measures by quartile categories of protein intake, adjusting for relevant confounders and covariates. Mean age was 59 ± 9 y (range: 29-86 y) and TP intake was 80 ± 27 g/d in men and 76 ± 26 g/d in women. In men and women, leg lean mass was higher in participants in the highest quartiles of TP and AP intake compared with those in the lowest quartiles of intake [least squares means (kg): TP-17.6 vs. 17.1 in men, P-trend: 0.005, and 11.7 vs. 11.4 in women, P-trend: 0.006; AP-17.6 vs. 17.1 in men, P-trend: 0.002, and 11.7 vs. 11.4 in women, P-trend: 0.003]. PP intake was not associated with lean mass in either sex. In men and women, quadriceps strength was higher in participants in the highest quartile of PP intake compared with those in the lowest quartile [least squares means (kg): 22.9 vs. 21.7 in men, P-trend: 0.01, and 19.0 vs. 18.2 in women, P-trend: 0.01]; this association was no longer significant after adjustment for fruit and vegetable intake (P-trend: 0.06 in men and 0.10 in women). Although no significant association was observed for AP intake in either sex, nonsignificant protective trends were observed for TP intake (P-trend: 0.08 in

Capsaicin-sensitive muscle afferents modulate the monosynaptic reflex in response to muscle ischemia and fatigue in the rat.

PubMed

Della Torre, G; Brunetti, O; Pettorossi, V E

2002-01-01

The role of muscle ischemia and fatigue in modulating the monosynaptic reflex was investigated in decerebrate and spinalized rats. Field potentials and fast motoneuron single units in the lateral gastrocnemious (LG) motor pool were evoked by dorsal root stimulation. Muscle ischemia was induced by occluding the LG vascular supply and muscle fatigue by prolonged tetanic electrical stimulation of the LG motor nerve. Under muscle ischemia the monosynaptic reflex was facilitated since the size of the early and late waves of the field potential and the excitability of the motoneuron units increased. This effect was abolished after L3-L6 dorsal rhizotomy, but it was unaffected after L3-L6 ventral rhizotomy. By contrast, the monosynaptic reflex was inhibited by muscle fatiguing stimulation, and this effect did not fully depend on the integrity of the dorsal root. However, when ischemia was combined with repetitive tetanic muscle stimulation the inhibitory effect of fatigue was significantly enhanced. Both the ischemia and fatigue effects were abolished by capsaicin injected into the LG muscle at a dose that blocked a large number of group III and IV muscle afferents. We concluded that muscle ischemia and fatigue activate different groups of muscle afferents that are both sensitive to capsaicin, but enter the spinal cord through different roots. They are responsible for opposite effects, when given separately: facilitation during ischemia and inhibition during fatigue; however, in combination, ischemia enhances the responsiveness of the afferent fibres to fatigue.

Quadriceps oxygenation during isometric exercise in sailing.

PubMed

Vogiatzis, I; Tzineris, D; Athanasopoulos, D; Georgiadou, O; Geladas, N

2008-01-01

The aim of the present study was to investigate why blood lactate after prolonged quadriceps contraction during hiking is only marginally increased. Eight sailors performed five 3-min hiking bouts interspersed with 5-s recovery periods. Whole body oxygen uptake, heart rate and lactate were recorded, along with continuous-wave near-infrared spectroscopy measures of quadriceps oxygenation. The time for 50% re-oxygenation was also assessed as an indication of the degree of localized oxygen delivery stress. Hiking elicited a significant (p = 0.001) increase in mean (+/- SD) heart rate (124 +/- 10 beats . min (-1)) which was accompanied by a disproportionately low oxygen uptake (12 +/- 2 ml.kg(-1).min(-1)). Lactate was significantly (p = 0.001) increased throughout hiking manoeuvres, though post-exercise it remained low (3.2 +/- 0.9 mmol.l(-1)). During the hiking bouts mean quadriceps oxygenation was significantly (p = 0.001) reduced compared to baseline (by 33 +/- 5%), indicating an imbalance between muscle oxygen accessibility and oxygen demand. During rest intervals quadriceps oxygenation was partially restored. After the end of the final bout the time for 50 % re-oxygenation was only 8 +/- 2 s, whereas recovery of quadriceps oxygenation and oxygen uptake was completed within 3 min. We conclude that the observed low lactate could be attributed to the small oxygen and energy deficits during hiking as the muscles' oxygen accessibility is presumably partially restored during the brief rest intervals.

Influence of Lumbar Muscle Fatigue on Trunk Adaptations during Sudden External Perturbations

PubMed Central

Abboud, Jacques; Nougarou, François; Lardon, Arnaud; Dugas, Claude; Descarreaux, Martin

2016-01-01

Introduction: When the spine is subjected to perturbations, neuromuscular responses such as reflex muscle contractions contribute to the overall balance control and spinal stabilization mechanisms. These responses are influenced by muscle fatigue, which has been shown to trigger changes in muscle recruitment patterns. Neuromuscular adaptations, e.g., attenuation of reflex activation and/or postural oscillations following repeated unexpected external perturbations, have also been described. However, the characterization of these adaptations still remains unclear. Using high-density electromyography (EMG) may help understand how the nervous system chooses to deal with an unknown perturbation in different physiological and/or mechanical perturbation environments. Aim: To characterize trunk neuromuscular adaptations following repeated sudden external perturbations after a back muscle fatigue task using high-density EMG. Methods: Twenty-five healthy participants experienced a series of 15 sudden external perturbations before and after back muscle fatigue. Erector spinae muscle activity was recorded using high-density EMG. Trunk kinematics during perturbation trials were collected using a 3-D motion analysis system. A two-way repeated measure ANOVA was conducted to assess: (1) the adaptation effect across trials; (2) the fatigue effect; and (3) the interaction effect (fatigue × adaptation) for the baseline activity, the reflex latency, the reflex peak and trunk kinematic variables (flexion angle, velocity and time to peak velocity). Muscle activity spatial distribution before and following the fatigue task was also compared using t-tests for dependent samples. Results: An attenuation of muscle reflex peak was observed across perturbation trials before the fatigue task, but not after. The spatial distribution of muscle activity was significantly higher before the fatigue task compared to post-fatigue trials. Baseline activity showed a trend to higher values after muscle

Asymmetry of quadriceps muscle oxygenation during elite short-track speed skating.

PubMed

Hesford, Catherine Mary; Laing, Stewart J; Cardinale, Marco; Cooper, Chris E

2012-03-01

It has been suggested that, because of the low sitting position in short-track speed skating, muscle blood flow is restricted, leading to decreases in tissue oxygenation. Therefore, wearable wireless-enabled near-infrared spectroscopy (NIRS) technology was used to monitor changes in quadriceps muscle blood volume and oxygenation during a 500-m race simulation in short-track speed skaters. Six elite skaters, all of Olympic standard (age = 23 ± 1.8 yr, height = 1.8 ± 0.1 m, mass = 80.1 ± 5.7 kg, midthigh skinfold thickness = 7 ± 2 mm), were studied. Subjects completed a 500-m race simulation time trial (TT). Whole-body oxygen consumption was simultaneously measured with muscle oxygenation in right and left vastus lateralis as measured by NIRS. Mean time for race completion was 44.8 ± 0.4 s. VO2 peaked 20 s into the race. In contrast, muscle tissue oxygen saturation (TSI%) decreased and plateaued after 8 s. Linear regression analysis showed that right leg TSI% remained constant throughout the rest of the TT (slope value = 0.01), whereas left leg TSI% increased steadily (slope value = 0.16), leading to a significant asymmetry (P < 0.05) in the final lap. Total muscle blood volume decreased equally in both legs at the start of the simulation. However, during subsequent laps, there was a strong asymmetry during cornering; when skaters traveled solely on the right leg, there was a decrease in its muscle blood volume, whereas an increase was seen in the left leg. NIRS was shown to be a viable tool for wireless monitoring of muscle oxygenation. The asymmetry in muscle desaturation observed on the two legs in short-track speed skating has implications for training and performance.

The 12-week progressive quadriceps resistance training improves muscle strength, exercise capacity and quality of life in patients with stable chronic heart failure.

PubMed

Jankowska, Ewa A; Wegrzynowska, Kinga; Superlak, Malgorzata; Nowakowska, Katarzyna; Lazorczyk, Malgorzata; Biel, Bartosz; Kustrzycka-Kratochwil, Dorota; Piotrowska, Katarzyna; Banasiak, Waldemar; Wozniewski, Marek; Ponikowski, Piotr

2008-10-30

Abnormalities in the skeletal musculature underlie exercise intolerance in chronic heart failure (CHF). We investigated, whether in CHF selective resistance training without accompanying aerobic regime favourably affects muscle strength, muscle mass and improves exercise capacity. Ten patients with stable ischaemic CHF in NYHA class III (9 men, age: 70+/-6 years [mean+/-SD], left ventricular ejection fraction: 30+/-5%, peak oxygen consumption [peak VO(2)]: 12.4+/-3.0 mL/min/kg) underwent the rehabilitation programme which consisted of a 12-week training phase (progressive resistance exercises restricted to the quadriceps muscles) followed by a 12-week detraining phase. All subjects completed a training phase of the programme with no adverse events. Resistance training markedly increased quadriceps strength (right leg: 260+/-34 vs. 352+/-28 N, left leg: 264+/-38 vs. 342+/-30 N, both p<0.01 - all comparisons: baseline vs. after training), but did not affect lean tissue mass of lower extremities (both p>0.2). It was accompanied by an improvement in clinical status (all NYHA III vs. all NYHA II, p<0.01), quality of life (Minnesota questionnaire: 44+/-15 vs. 33+/-18 points, p<0.05), exercise capacity assessed using a distance during 6-minute walk test (6MWT: 362+/-83 vs. 455+/-71 m, p<0.01), but not peak VO(2) (p>0.2). Plasma NT-proBNP remained unchanged during the training. At the end of detraining phase, only a partial improvement in quadriceps strength (p<0.05), a 6MWT distance (p<0.05) and NYHA class (p=0.07 vs. baseline) persisted. Applied resistance quadriceps training is safe in patients with CHF. It increases muscle strength, improves clinical status, exercise capacity, and quality of life.

Electromyogram and perceived fatigue changes in the trapezius muscle during typewriting and recovery.

PubMed

Kimura, Mitsutoshi; Sato, Hirotaka; Ochi, Mamoru; Hosoya, Satoshi; Sadoyama, Tsugutake

2007-05-01

The purpose of the present study was to investigate the development and recovery of muscle fatigue in the upper trapezius muscle by analyzing electromyographic signals. Six male subjects performed a simulated typewriting task for four 25-min sessions. During fatigue and the following rest periods, subjective fatigue and surface electromyography (EMG) from the trapezius muscle during isometric contraction at 30% maximum voluntary contraction (MVC) were periodically measured in the interval. We detected a significant decrease in muscle fiber conduction velocity (MFCV) (P = 0.008) and median frequency (MDF) (P = 0.026) as well as an increase in root mean square (RMS) (P = 0.039) and subjective fatigue (P = 0.0004) during the fatigue period. During the recovery period, subjective fatigue decreased drastically and significantly (P = 0.0004), however, the EMG parameters did not recover completely. Thus, physiological muscle fatigue in the trapezius developed in accordance with subjective muscle fatigue during typewriting. On the other hand, differences between the physiological and subjective parameters were found during recovery. Further studies should be necessary to reveal the discrepancy could be a major factor of a transition from temporal phenomena to serious chronic muscle fatigue and to identify the necessity of some guidelines to prevent VDT work-related chronic muscle fatigue in the trapezius.

Mechanisms of in vivo muscle fatigue in humans: investigating age‐related fatigue resistance with a computational model

PubMed Central

Callahan, Damien M.; Umberger, Brian R.

2016-01-01

Key points Muscle fatigue can be defined as the transient decrease in maximal force that occurs in response to muscle use. Fatigue develops because of a complex set of changes within the neuromuscular system that are difficult to evaluate simultaneously in humans.The skeletal muscle of older adults fatigues less than that of young adults during static contractions. The potential sources of this difference are multiple and intertwined.To evaluate the individual mechanisms of fatigue, we developed an integrative computational model based on neural, biochemical, morphological and physiological properties of human skeletal muscle.Our results indicate first that the model provides accurate predictions of fatigue and second that the age‐related resistance to fatigue is due largely to a lower reliance on glycolytic metabolism during contraction.This model should prove useful for generating hypotheses for future experimental studies into the mechanisms of muscle fatigue. Abstract During repeated or sustained muscle activation, force‐generating capacity becomes limited in a process referred to as fatigue. Multiple factors, including motor unit activation patterns, muscle fibre contractile properties and bioenergetic function, can impact force‐generating capacity and thus the potential to resist fatigue. Given that neuromuscular fatigue depends on interrelated factors, quantifying their independent effects on force‐generating capacity is not possible in vivo. Computational models can provide insight into complex systems in which multiple inputs determine discrete outputs. However, few computational models to date have investigated neuromuscular fatigue by incorporating the multiple levels of neuromuscular function known to impact human in vivo function. To address this limitation, we present a computational model that predicts neural activation, biomechanical forces, intracellular metabolic perturbations and, ultimately, fatigue during repeated isometric contractions

Fatigue-related firing of muscle nociceptors reduces voluntary activation of ipsilateral but not contralateral lower limb muscles.

PubMed

Kennedy, David S; Fitzpatrick, Siobhan C; Gandevia, Simon C; Taylor, Janet L

2015-02-15

During fatiguing upper limb exercise, maintained firing of group III/IV muscle afferents can limit voluntary drive to muscles within the same limb. It is not known if this effect occurs in the lower limb. We investigated the effects of group III/IV muscle afferent firing from fatigued ipsilateral and contralateral extensor muscles and ipsilateral flexor muscles of the knee on voluntary activation of the knee extensors. In three experiments, we examined voluntary activation of the knee extensors by measuring changes in superimposed twitches evoked by femoral nerve stimulation. Subjects attended on 2 days for each experiment. On one day a sphygmomanometer cuff occluded blood flow of the fatigued muscles to maintain firing of group III/IV muscle afferents. After a 2-min extensor contraction (experiment 1; n = 9), mean voluntary activation was lower with than without maintained ischemia (47 ± 19% vs. 87 ± 8%, respectively; P < 0.001). After a 2-min knee flexor maximal voluntary contraction (MVC) (experiment 2; n = 8), mean voluntary activation was also lower with than without ischemia (59 ± 21% vs. 79 ± 9%; P < 0.01). After the contralateral (left) MVC (experiment 3; n = 8), mean voluntary activation of the right leg was similar with or without ischemia (92 ± 6% vs. 93 ± 4%; P = 0.65). After fatiguing exercise, activity in group III/IV muscle afferents reduces voluntary activation of the fatigued muscle and nonfatigued antagonist muscles in the same leg. However, group III/IV muscle afferents from the fatigued left leg had no effect on the unfatigued right leg. This suggests that any "crossover" of central fatigue in the lower limbs is not mediated by group III/IV muscle afferents. Copyright © 2015 the American Physiological Society.

Noninvasive evaluation of muscle mass by ultrasonography of quadriceps femoris muscle in End-Stage Renal Disease patients on hemodialysis.

PubMed

Sabatino, Alice; Regolisti, Giuseppe; Delsante, Marco; Di Motta, Tommaso; Cantarelli, Chiara; Pioli, Sarah; Grassi, Giulia; Batini, Valentina; Gregorini, Mariacristina; Fiaccadori, Enrico

2018-05-19

Protein-Energy Wasting (PEW) is a pathological condition of renal patients with advanced Chronic Kidney Disease characterized by a progressive reduction of energy and protein assets. Nutritional status assessment, especially for what concerns muscle mass, is essential for both the identification of patients at risk for the development of PEW, as well as monitoring the effects of nutritional interventions. Ultrasound methods are easily applicable at the bedside for quantitative assessment of skeletal muscle. The present study was aimed at evaluating quadriceps rectus femoris thickness (QRFT) and quadriceps vastus intermedius thickness (QVIT) in patients on chronic hemodialysis. This was a prospective observational study. Three groups of adult patients were studied: young healthy subjects, well-nourished hospitalized patients with normal renal function, and End-Stage Renal Disease patients on hemodialysis (ESRD-HD). QRFT and QVIT were measured at two sites bilaterally (8 measures/patient) and were compared between groups, and also between subgroups of ESRD-HD patients stratified on the basis of conventional nutritional status parameters. We enrolled 35 healthy subjects, 30 hospitalized patients, and 121 ESRD-HD patients on hemodialysis. QRFT and QVIT of ESRD patients on hemodialysis were lower than those of both control groups (P < 0.001). After stratifying ESRD patients into subgroups based on nutritional variable cut-offs commonly used to define PEW in this clinical setting (BMI [≥ 23 vs <23 kg/m 2 ], albumin [≥3.8 vs <3.8 g/dL]) and malnutrition inflammation score (MIS) status (<6 vs ≥6), QRFT and QVIT of patients with worse nutritional status were significantly lower than those of well-nourished ESRD-HD patients (P value range: <0.001 to <0.05). Skeletal muscle ultrasound is a simple and easily applicable bedside technique in the dialysis units, and could represent an adequate tool for the identification of patients with reduced muscle mass. Copyright �

Quantifying the history dependency of muscle recovery from a fatiguing intermittent task.

PubMed

Rashedi, Ehsan; Nussbaum, Maury A

2017-01-25

Muscle fatigue and recovery are complex processes influencing muscle force generation capacity. While fatigue reduces this capacity, recovery acts to restore the unfatigued muscle state. Many factors can potentially affect muscle recovery, and among these may be a task dependency of recovery following an exercise. However, little has been reported regarding the history dependency of recovery after fatiguing contractions. We examined the dependency of muscle recovery subsequent to four different histories of fatiguing muscle contractions, imposed using two cycle times (30 and 60s) during low to moderate levels (15% and 25% of maximum voluntary contraction (MVC)) of intermittent static exertions involving index finger abduction. MVC and low-frequency electrical stimulation (LFES) measures (i.e., magnitude, rise and relaxation rates) of muscle capacity were used, all of which indicated a dependency of muscle recovery on the muscle capacity state existing immediately after fatiguing exercise. This dependency did not appear to be modified by either the cycle time or exertion level leading to that state. These results imply that the post-exercise rate of recovery is primarily influenced by the immediate post-exercise muscle contractile status (estimated by MVC and LFES measures). Such results may help improve existing models of muscle recovery, facilitating more accurate predictions of localized muscle fatigue development and thereby helping to enhance muscle performance and reduce the risk of injury. Copyright © 2016 Elsevier Ltd. All rights reserved.

β2-Adrenergic stimulation enhances Ca2+ release and contractile properties of skeletal muscles, and counteracts exercise-induced reductions in Na+–K+-ATPase Vmax in trained men

PubMed Central

Hostrup, M; Kalsen, A; Ørtenblad, N; Juel, C; Mørch, K; Rzeppa, S; Karlsson, S; Backer, V; Bangsbo, J

2014-01-01

The aim of the present study was to examine the effect of β2-adrenergic stimulation on skeletal muscle contractile properties, sarcoplasmic reticulum (SR) rates of Ca2+ release and uptake, and Na+–K+-ATPase activity before and after fatiguing exercise in trained men. The study consisted of two experiments (EXP1, n = 10 males, EXP2, n = 20 males), where β2-adrenoceptor agonist (terbutaline) or placebo was randomly administered in double-blinded crossover designs. In EXP1, maximal voluntary isometric contraction (MVC) of m. quadriceps was measured, followed by exercise to fatigue at 120% of maximal oxygen uptake (). A muscle biopsy was taken after MVC (non-fatigue) and at time of fatigue. In EXP2, contractile properties of m. quadriceps were measured with electrical stimulations before (non-fatigue) and after two fatiguing 45 s sprints. Non-fatigued MVCs were 6 ± 3 and 6 ± 2% higher (P < 0.05) with terbutaline than placebo in EXP1 and EXP2, respectively. Furthermore, peak twitch force was 11 ± 7% higher (P < 0.01) with terbutaline than placebo at non-fatigue. After sprints, MVC declined (P < 0.05) to the same levels with terbutaline as placebo, whereas peak twitch force was lower (P < 0.05) and half-relaxation time was prolonged (P < 0.05) with terbutaline. Rates of SR Ca2+ release and uptake at 400 nm [Ca2+] were 15 ± 5 and 14 ± 5% (P < 0.05) higher, respectively, with terbutaline than placebo at non-fatigue, but declined (P < 0.05) to similar levels at time of fatigue. Na+–K+-ATPase activity was unaffected by terbutaline compared with placebo at non-fatigue, but terbutaline counteracted exercise-induced reductions in maximum rate of activity (Vmax) at time of fatigue. In conclusion, increased contractile force induced by β2-adrenergic stimulation is associated with enhanced rate of Ca2+ release in humans. While β2-adrenergic stimulation elicits positive inotropic and lusitropic effects on non-fatigued m. quadriceps, these effects are blunted when

Gender differences in tibio-femoral kinematics and quadriceps muscle force during weight-bearing knee flexion in vitro.

PubMed

Wünschel, Markus; Wülker, Nikolaus; Müller, Otto

2013-11-01

Females have a higher risk in terms of anterior cruciate ligament injuries during sports than males. Reasons for this fact may be different anatomy and muscle recruitment patterns leading to less protection for the cruciate- and collateral-ligaments. This in vitro study aims to evaluate gender differences in knee joint kinematics and muscle force during weight-bearing knee flexions. Thirty-four human knee specimens (17 females/17 males) were mounted on a dynamic knee simulator. Weight-bearing single-leg knee flexions were performed with different amounts of simulated body weight (BW). Gender-specific kinematics was measured with an ultrasonic motion capture system and different loading conditions were examined. Knee joint kinematics did not show significant differences regarding anteroposterior and medial-lateral movement as well as tibial varus-valgus and internal-external rotation. This applied to all simulated amounts of BW. Simulating 100 N BW in contrast to AF50 led to a significant higher quadriceps overall force in female knees from 45° to 85° of flexion in contrast to BW 50 N. In these female specimens, the quadriceps overall force was about 20 % higher than in male knees being constant in higher flexion angles. It is indicated by our results that in a squatting movement females compared with males produce higher muscle forces, suggesting an increased demand for muscular stabilization, whereas tibio-femoral kinematics was similar for both genders.

Use of muscle synergies and wavelet transforms to identify fatigue during squatting.

PubMed

Smale, Kenneth B; Shourijeh, Mohammad S; Benoit, Daniel L

2016-06-01

The objective of this study was to supplement continuous wavelet transforms with muscle synergies in a fatigue analysis to better describe the combination of decreased firing frequency and altered activation profiles during dynamic muscle contractions. Nine healthy young individuals completed the dynamic tasks before and after they squatted with a standard Olympic bar until complete exhaustion. Electromyography (EMG) profiles were analyzed with a novel concatenated non-negative matrix factorization method that decomposed EMG signals into muscle synergies. Muscle synergy analysis provides the activation pattern of the muscles while continuous wavelet transforms output the temporal frequency content of the EMG signals. Synergy analysis revealed subtle changes in two-legged squatting after fatigue while differences in one-legged squatting were more pronounced and included the shift from a general co-activation of muscles in the pre-fatigue state to a knee extensor dominant weighting post-fatigue. Continuous wavelet transforms showed major frequency content decreases in two-legged squatting after fatigue while very few frequency changes occurred in one-legged squatting. It was observed that the combination of methods is an effective way of describing muscle fatigue and that muscle activation patterns play a very important role in maintaining the overall joint kinetics after fatigue. Copyright © 2016 Elsevier Ltd. All rights reserved.

Association between leg strength and muscle cross-sectional area of the quadriceps femoris with the physical activity level in octogenarians.

PubMed

Latorre-Román, Pedro Á; Arévalo-Arévalo, Juan Manuel; García-Pinillos, Felipe

2016-06-03

Aging is a complex physiological process whose main feature is the progressive loss of functionality, which may be delayed or attenuated by improving physical fitness.  To determine the association between leg strength and the muscle cross-sectional area of the quadriceps femoris in relation to physical activity level in the elderly.  Thirty-two functionally autonomous people over 80 years (men: 82.80±2.09 years; women: 83.77±4.09 years) participated in this study. The Barthel Index, the Yale Physical Activity Survey and the Chair Stand Test were the instruments used.  There were significant differences between sexes in muscle area (p<0.001) in the Chair Stand Test (p=0.028) and the walk index (p=0.029), with higher values in men. The muscle area and the Chair Stand Test correlated significantly with the walk index (r=0.445, p<0.005, and r=0.522, p<0.001, respectively) and the total weekly activity index (r=0.430, p<0.005, and r=0.519, p<0.001, respectively). In the multiple linear regression models for the total weekly activity index, muscle area and the Chair Stand Test, only the latter behaved as a predictor variable.  Muscle strength and muscle mass of quadriceps showed a significant association with the physical activity level in older people. Leg muscle strength was useful to reveal muscle mass and physical activity level in older people, which is relevant as a clinical practice indicator.

Validity and reliability of isometric, isokinetic and isoinertial modalities for the assessment of quadriceps muscle strength in patients with total knee arthroplasty.

PubMed

Lienhard, K; Lauermann, S P; Schneider, D; Item-Glatthorn, J F; Casartelli, N C; Maffiuletti, N A

2013-12-01

Reliability of isometric, isokinetic and isoinertial modalities for quadriceps strength evaluation, and the relation between quadriceps strength and physical function was investigated in 29 total knee arthroplasty (TKA) patients, with an average age of 63 years. Isometric maximal voluntary contraction torque, isokinetic peak torque, and isoinertial one-repetition maximum load of the involved and uninvolved quadriceps were evaluated as well as objective (walking parameters) and subjective physical function (WOMAC). Reliability was good and comparable for the isometric, isokinetic, and isoinertial strength outcomes on both sides (intraclass correlation coefficient range: 0.947-0.966; standard error of measurement range: 5.1-9.3%). Involved quadriceps strength was significantly correlated to walking speed (r range: 0.641-0.710), step length (r range: 0.685-0.820) and WOMAC function (r range: 0.575-0.663), independent from the modality (P < 0.05). Uninvolved quadriceps strength was also significantly correlated to walking speed (r range: 0.413-0.539), step length (r range: 0.514-0.608) and WOMAC function (r range: 0.374-0.554) (P < 0.05), except for WOMAC function/isokinetic peak torque (P > 0.05). In conclusion, isometric, isokinetic, and isoinertial modalities ensure valid and reliable assessment of quadriceps muscle strength in TKA patients. Copyright © 2013 Elsevier Ltd. All rights reserved.

Muscle Damage and Its Relationship with Muscle Fatigue During a Half-Iron Triathlon

PubMed Central

Coso, Juan Del; González-Millán, Cristina; Salinero, Juan José; Abián-Vicén, Javier; Soriano, Lidón; Garde, Sergio; Pérez-González, Benito

2012-01-01

Background To investigate the cause/s of muscle fatigue experienced during a half-iron distance triathlon. Methodology/Principal Findings We recruited 25 trained triathletes (36±7 yr; 75.1±9.8 kg) for the study. Before and just after the race, jump height and leg muscle power output were measured during a countermovement jump on a force platform to determine leg muscle fatigue. Body weight, handgrip maximal force and blood and urine samples were also obtained before and after the race. Blood myoglobin and creatine kinase concentrations were determined as markers of muscle damage. Results Jump height (from 30.3±5.0 to 23.4±6.4 cm; P<0.05) and leg power output (from 25.6±2.9 to 20.7±4.6 W · kg−1; P<0.05) were significantly reduced after the race. However, handgrip maximal force was unaffected by the race (430±59 to 430±62 N). Mean dehydration after the race was 2.3±1.2% with high inter-individual variability in the responses. Blood myoglobin and creatine kinase concentration increased to 516±248 µg · L−1 and 442±204 U · L−1, respectively (P<0.05) after the race. Pre- to post-race jump change did not correlate with dehydration (r = 0.16; P>0.05) but significantly correlated with myoglobin concentration (r = 0.65; P<0.001) and creatine kinase concentration (r = 0.54; P<0.001). Conclusions/significance During a half-iron distance triathlon, the capacity of leg muscles to produce force was notably diminished while arm muscle force output remained unaffected. Leg muscle fatigue was correlated with blood markers of muscle damage suggesting that muscle breakdown is one of the most relevant sources of muscle fatigue during a triathlon. PMID:22900101

The influence of lumbar extensor muscle fatigue on lumbar-pelvic coordination during weightlifting.

PubMed

Hu, Boyi; Ning, Xiaopeng

2015-01-01

Lumbar muscle fatigue is a potential risk factor for the development of low back pain. In this study, we investigated the influence of lumbar extensor muscle fatigue on lumbar-pelvic coordination patterns during weightlifting. Each of the 15 male subjects performed five repetitions of weightlifting tasks both before and after a lumbar extensor muscle fatiguing protocol. Lumbar muscle electromyography was collected to assess fatigue. Trunk kinematics was recorded to calculate lumbar-pelvic continuous relative phase (CRP) and CRP variability. Results showed that fatigue significantly reduced the average lumbar-pelvic CRP value (from 0.33 to 0.29 rad) during weightlifting. The average CRP variability reduced from 0.17 to 0.15 rad, yet this change ws statistically not significant. Further analyses also discovered elevated spinal loading during weightlifting after the development of lumbar extensor muscle fatigue. Our results suggest that frequently experienced lumbar extensor muscle fatigue should be avoided in an occupational environment. Lumbar extensor muscle fatigue generates more in-phase lumbar-pelvic coordination patterns and elevated spinal loading during lifting. Such increase in spinal loading may indicate higher risk of back injury. Our results suggest that frequently experienced lumbar muscle fatigue should be avoided to reduce the risk of LBP.

Coordinated collagen and muscle protein synthesis in human patella tendon and quadriceps muscle after exercise

PubMed Central

Miller, Benjamin F; Olesen, Jens L; Hansen, Mette; Døssing, Simon; Crameri, Regina M; Welling, Rasmus J; Langberg, Henning; Flyvbjerg, Allan; Kjaer, Michael; Babraj, John A; Smith, Kenneth; Rennie, Michael J

2005-01-01

We hypothesized that an acute bout of strenuous, non-damaging exercise would increase rates of protein synthesis of collagen in tendon and skeletal muscle but these would be less than those of muscle myofibrillar and sarcoplasmic proteins. Two groups (n = 8 and 6) of healthy young men were studied over 72 h after 1 h of one-legged kicking exercise at 67% of maximum workload (Wmax). To label tissue proteins in muscle and tendon primed, constant infusions of [1-13C]leucine or [1-13C]valine and flooding doses of [15N] or [13C]proline were given intravenously, with estimation of labelling in target proteins by gas chromatography–mass spectrometry. Patellar tendon and quadriceps biopsies were taken in exercised and rested legs at 6, 24, 42 or 48 and 72 h after exercise. The fractional synthetic rates of all proteins were elevated at 6 h and rose rapidly to peak at 24 h post exercise (tendon collagen (0.077% h−1), muscle collagen (0.054% h−1), myofibrillar protein (0.121% h−1), and sarcoplasmic protein (0.134% h−1)). The rates decreased toward basal values by 72 h although rates of tendon collagen and myofibrillar protein synthesis remained elevated. There was no tissue damage of muscle visible on histological evaluation. Neither tissue microdialysate nor serum concentrations of IGF-I and IGF binding proteins (IGFBP-3 and IGFBP-4) or procollagen type I N-terminal propeptide changed from resting values. Thus, there is a rapid increase in collagen synthesis after strenuous exercise in human tendon and muscle. The similar time course of changes of protein synthetic rates in different cell types supports the idea of coordinated musculotendinous adaptation. PMID:16002437

Selective hypertrophy of the quadriceps musculature after 14 weeks of isokinetic and conventional resistance training.

PubMed

Matta, Thiago Torres; Nascimento, Francisco Xavier; Trajano, Gabriel S; Simão, Roberto; Willardson, Jeffrey Michael; Oliveira, Liliam Fernandes

2017-03-01

One of the fundamental adaptations observed with resistance training (RT) is muscle hypertrophy. Conventional and isokinetic machines provide different forms of mechanical stress, and it is possible that these two training modes could promote differing degrees of hypertrophic adaptations. There is a lack of data comparing the selective hypertrophy of the quadriceps musculature after training with a conventional knee extension machine versus an isokinetic machine. The purpose of this study was to evaluate the selective hypertrophy of the quadriceps musculature and knee extension maximal isometric torque after 14 weeks of conventional versus isokinetic RT. Thirty-five men were assigned to three groups: control group and training groups (conventional and isokinetic) performed three sets of unilateral knee extensions per session with a progressive loading scheme twice a week. Prior to and following the intervention, maximal isometric knee extensor torque was measured using an isokinetic dynamometer, and muscle thickness (MT) of quadriceps femoris muscles was assessed via ultrasound. The results indicated non-uniform changes in MT between the muscles that comprise the quadriceps femoris group. For the conventional group, significantly greater increases in rectus femoris thickness were evident versus all other quadriceps muscles (14%). For the isokinetic group, increases in RF thickness (11%) were significantly greater in comparison with the vastus intermedius only. Although the muscle thickness did not increase for all the quadriceps femoris muscles, the relative rectus femoris adaptation suggested a selective hypertrophy favouring this portion. © 2015 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

Massage therapy decreases pain and perceived fatigue after long-distance Ironman triathlon: a randomised trial.

PubMed

Nunes, Guilherme S; Bender, Paula Urio; de Menezes, Fábio Sprada; Yamashitafuji, Igor; Vargas, Valentine Zimermann; Wageck, Bruna

2016-04-01

Can massage therapy reduce pain and perceived fatigue in the quadriceps of athletes after a long-distance triathlon race (Ironman)? Randomised, controlled trial with concealed allocation, intention-to-treat analysis and blinded outcome assessors. Seventy-four triathlon athletes who completed an entire Ironman triathlon race and whose main complaint was pain in the anterior portion of the thigh. The experimental group received massage to the quadriceps, which was aimed at recovery after competition, and the control group rested in sitting. The outcomes were pain and perceived fatigue, which were reported using a visual analogue scale, and pressure pain threshold at three points over the quadriceps muscle, which was assessed using digital pressure algometry. The experimental group had significantly lower scores than the control group on the visual analogue scale for pain (MD -7 mm, 95% CI -13 to -1) and for perceived fatigue (MD -15 mm, 95% CI -21 to -9). There were no significant between-group differences for the pressure pain threshold at any of the assessment points. Massage therapy was more effective than no intervention on the post-race recovery from pain and perceived fatigue in long-distance triathlon athletes. Brazilian Registry of Clinical Trials, RBR-4n2sxr. Copyright © 2016 Australian Physiotherapy Association. Published by Elsevier B.V. All rights reserved.

Neural Contributions to Muscle Fatigue: From the Brain to the Muscle and Back Again

PubMed Central

Taylor, Janet L.; Amann, Markus; Duchateau, Jacques; Meeusen, Romain; Rice, Charles L.

2016-01-01

During exercise, there is a progressive reduction in the ability to produce muscle forces. Processes within the nervous system, as well as within the muscles contribute to this fatigue. In addition to impaired function of the motor system, sensations associated with fatigue, and impairment of homeostasis can contribute to impairment of performance during exercise. This review discusses some of the neural changes that accompany exercise and the development of fatigue. The role of brain monoaminergic neurotransmitter systems in whole-body endurance performance is discussed, particularly with regard to exercise in hot environments. Next, fatigue-related alterations in the neuromuscular pathway are discussed in terms of changes in motor unit firing, motoneuron excitability and motor cortical excitability. These changes have mostly been investigated during single-limb isometric contractions. Finally, the small-diameter muscle afferents that increase firing with exercise and fatigue are discussed. These afferents have roles in cardiovascular and respiratory responses to exercise, and in impairment of exercise performance through interaction with the motor pathway, as well as providing sensations of muscle discomfort. Thus, changes at all levels of the nervous system including the brain, spinal cord, motor output, sensory input and autonomic function occur during exercise and fatigue. The mix of influences and the importance of their contribution varies with the type of exercise being performed. PMID:27003703

Sites of Failure in Muscle Fatigue

DTIC Science & Technology

2001-10-25

anticipate to the taps. At the beginning of the experiment, tapping force was gradually increased until significant triceps muscle contraction was elicited...367-374, 1986. [11] J. A. Stephens and A. Taylor, "Fatigue of maintained voluntary muscle contraction in man," J. Physiol. (London), vol. 220, pp. 1-18, 1972.

Mechanisms Explaining Muscle Fatigue and Muscle Pain in Patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS): a Review of Recent Findings.

PubMed

Gerwyn, Morris; Maes, Michael

2017-01-01

Here, we review potential causes of muscle dysfunction seen in many patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) such as the effects of oxidative and nitrosative stress (O&NS) and mitochondrial impairments together with reduced heat shock protein production and a range of metabolic abnormalities. Several studies published in the last few years have highlighted the existence of chronic O&NS, inflammation, impaired mitochondrial function and reduced heat shock protein production in many patients with ME/CFS. These studies have also highlighted the detrimental effects of chronically elevated O&NS on muscle functions such as reducing the time to muscle fatigue during exercise and impairing muscle contractility. Mechanisms have also been revealed by which chronic O&NS and or impaired heat shock production may impair muscle repair following exercise and indeed the adaptive responses in the striated muscle to acute and chronic increases in physical activity. The presence of chronic O&NS, low-grade inflammation and impaired heat shock protein production may well explain the objective findings of increased muscle fatigue, impaired contractility and multiple dimensions of exercise intolerance in many patients with ME/CFS.

Effects of inspiratory muscle training on resistance to fatigue of respiratory muscles during exhaustive exercise.

PubMed

Segizbaeva, M O; Timofeev, N N; Donina, Zh A; Kur'yanovich, E N; Aleksandrova, N P

2015-01-01

The aim of this study was to assess the effect of inspiratory muscle training (IMT) on resistance to fatigue of the diaphragm (D), parasternal (PS), sternocleidomastoid (SCM) and scalene (SC) muscles in healthy humans during exhaustive exercise. Daily inspiratory muscle strength training was performed for 3 weeks in 10 male subjects (at a pressure threshold load of 60% of maximal inspiratory pressure (MIP) for the first week, 70% of MIP for the second week, and 80% of MIP for the third week). Before and after training, subjects performed an incremental cycle test to exhaustion. Maximal inspiratory pressure and EMG-analysis served as indices of inspiratory muscle fatigue assessment. The before-to-after exercise decreases in MIP and centroid frequency (fc) of the EMG (D, PS, SCM, and SC) power spectrum (P<0.05) were observed in all subjects before the IMT intervention. Such changes were absent after the IMT. The study found that in healthy subjects, IMT results in significant increase in MIP (+18%), a delay of inspiratory muscle fatigue during exhaustive exercise, and a significant improvement in maximal work performance. We conclude that the IMT elicits resistance to the development of inspiratory muscles fatigue during high-intensity exercise.

Fatigue is associated with muscle weakness in Ehlers-Danlos syndrome: an explorative study.

PubMed

Voermans, N C; Knoop, H; Bleijenberg, G; van Engelen, B G

2011-06-01

Ehlers-Danlos syndrome (EDS) is a clinically and genetically heterogeneous group of inherited connective tissue disorders characterised by joint hypermobility, skin hyperextensibility and tissue fragility. It has recently been shown that muscle weakness occurs frequently in EDS, and that fatigue is a common and clinically important symptom. The aim of this study was to investigate the relationship between fatigue severity and subjective and objective measures of muscle weakness. Furthermore, the predictive value of muscle weakness for fatigue severity was determined, together with that of pain and physical activity. An explorative, cross-sectional, observational study. Thirty EDS patients, recruited from the Dutch patient association, were investigated at the neuromuscular outpatient department of a tertiary referral centre in The Netherlands. Muscle strength measured with manual muscle strength testing and hand-held dynamometry. Self-reported muscle weakness, pain, physical activity levels and fatigue were assessed with standardised questionnaires. Fatigue severity in EDS was significantly correlated with measured and self-reported muscle weakness (r=-0.408 for manual muscle strength, r=0.461 for hand-held dynamometry and r=0.603 for self-reported muscle weakness). Both muscle weakness and pain severity were significant predictors of fatigue severity in a multiple regression analysis. The results suggest a positive and direct relationship between fatigue severity and muscle weakness in EDS. Future research should focus on the relationship between fatigue, muscle weakness and objectively measured physical activity, preferably in a larger cohort of EDS patients. Copyright © 2010 Chartered Society of Physiotherapy. Published by Elsevier Ltd. All rights reserved.

Muscle fatigue evaluation of astronaut upper limb based on sEMG and subjective assessment

NASA Astrophysics Data System (ADS)

Zu, Xiaoqi; Zhou, Qianxiang; Li, Yun

2012-07-01

All movements are driven by muscle contraction, and it is easy to cause muscle fatigue. Evaluation of muscle fatigue is a hot topic in the area of astronaut life support training and rehabilitation. If muscle gets into fatigue condition, it may reduce work efficiency and has an impact on psychological performance. Therefore it is necessary to develop an accurate and usable method on muscle fatigue evaluation of astronaut upper limb. In this study, we developed a method based on surface electromyography (sEMG) and subjective assessment (Borg scale) to evaluate local muscle fatigue. Fifteen healthy young male subjects participated in the experiment. They performed isometric muscle contractions of the upper limb. sEMG of the biceps brachii were recorded during the entire process of isotonic muscle contraction and Borg scales of muscle fatigue were collected in certain times. sEMG were divided into several parts, and then mean energy of each parts were calculated by the one-twelfth band octave method. Equations were derived based on the relationship between the mean energy of sEMG and Borg scale. The results showed that cubic curve could describe the degree of local muscle fatigue, and could be used to evaluate and monitor local muscle fatigue during the entire process.

Fatigue-induced changes in group IV muscle afferent activity: differences between high- and low-frequency electrically induced fatigues.

PubMed

Darques, J L; Jammes, Y

1997-03-07

Recordings of group IV afferent activity of tibialis anterior muscle were performed in paralysed rabbits during runs of electrically induced fatigue produced by direct muscle stimulation at a high (100 Hz, high-frequency fatigue HFF) or a low rate (10 Hz, low-frequency fatigue LFF). In addition to analysis of afferent nerve action potentials, muscle force and compound muscle action potentials (M waves) elicited by direct muscle stimulation with single shocks were recorded. Changes in M wave configuration were used as an index of the altered propagation of membrane potentials and the associated efflux of potassium from muscle fibers. The data show that increased group IV afferent activity occurred during LFF as well as HFF trials and developed parallel with force failure. Enhanced afferent activity was significantly higher during LFF (maximal delta f(impulses) = 249 +/- 35%) than HFF (147 +/- 45%). No correlation was obtained between the responses of group IV afferents to LFF or to pressure exerted on tibialis anterior muscle. On the other hand, decreased M wave amplitude was minimal with LFF while it was pronounced with HFF. Close correlations were found between fatigue-induced activation of group IV afferents and decreases in force or M wave amplitude, but their strength was significantly higher with LFF compared to HFF. Thus, electrically induced fatigue activates group IV muscle afferents with a prominent effect of low-frequency stimulation. The mechanism of muscle afferent stimulation does not seem to be due to the sole increase in extracellular potassium concentration, but also by the efflux of muscle metabolites, present during fatiguing contractions at low rate of stimulation.

Assessment of Muscle Fatigue Associated with Prolonged Standing in the Workplace

PubMed Central

Omar, Abdul Rahman; Saman, Alias Mohd; Othman, Ibrahim

2012-01-01

Objectives The objectives of this study were to determine the psychological fatigue and analyze muscle activity of production workers who are performing processes jobs while standing for prolonged time periods. Methods The psychological fatigue experienced by the workers was obtained through questionnaire surveys. Meanwhile, muscle activity has been analyzed using surface electromyography (sEMG) measurement. Lower extremities muscles include: erector spinae, tibialis anterior, and gastrocnemius were concurrently measured for more than five hours of standing. Twenty male production workers in a metal stamping company participated as subjects in this study. The subjects were required to undergo questionnaire surveys and sEMG measurement. Results Results of the questionnaire surveys found that all subjects experienced psychological fatigue due to prolonged standing jobs. Similarly, muscle fatigue has been identified through sEMG measurement. Based on the non-parametric statistical test using the Spearman's rank order correlation, the left erector spinae obtained a moderate positive correlation and statistically significant (rs = 0.552, p < 0.05) between the results of questionnaire surveys and sEMG measurement. Conclusion Based on this study, the authors concluded that prolonged standing was contributed to psychological fatigue and to muscle fatigue among the production workers. PMID:22953228

Challenging the role of pH in skeletal muscle fatigue.

PubMed

Stackhouse, S K; Reisman, D S; Binder-Macleod, S A

2001-12-01

Muscle fatigue is frequently defined as a temporary loss in force- or torque-generating ability because of recent, repetitive muscle contraction (1). The development of this temporary loss of force is a complex process and results from the failure of a number of processes, including motor unit recruitment and firing rate, chemical transmission across the neuromuscular junction, propagation of the action potential along the muscle membrane and T tubules, Ca2+ release from the sarcoplasmic reticulum (SR), Ca2+ binding to troponin C, and cross-bridge cycling (for detailed reviews, see Bigland-Ritchie and Woods(1), McLester(2), and Favero(3)). Muscle fatigue may limit the time a person can stand, the distance a person can ambulate, or the number of stairs a person can ascend or descend. In practical terms, however, we cannot know what actually leads to a decline in function for a given patient. For a phenomenon that may have profound clinical implications, muscle fatigue often receives inadequate attention in physiology textbooks, many of which contain a page or less of information on the entire topic (4-8). In addition, many textbooks report that muscle fatigue is mainly the result of a decrease in pH within the muscle cell due to a rise in hydrogen ion concentration ([H+]) resulting from anaerobic metabolism and the accumulation of lactic acid (6-8). Recent literature, however, contradicts this assertion (9-10). The purpose of this update, therefore, is to provide a brief review of the role of pH in the development of muscle fatigue.

Method to Reduce Muscle Fatigue During Transcutaneous Neuromuscular Electrical Stimulation in Major Knee and Ankle Muscle Groups.

PubMed

Sayenko, Dimitry G; Nguyen, Robert; Hirabayashi, Tomoyo; Popovic, Milos R; Masani, Kei

2015-09-01

A critical limitation with transcutaneous neuromuscular electrical stimulation as a rehabilitative approach is the rapid onset of muscle fatigue during repeated contractions. We have developed a method called spatially distributed sequential stimulation (SDSS) to reduce muscle fatigue by distributing the center of electrical field over a wide area within a single stimulation site, using an array of surface electrodes. To extend the previous findings and to prove feasibility of the method by exploring the fatigue-reducing ability of SDSS for lower limb muscle groups in the able-bodied population, as well as in individuals with spinal cord injury (SCI). SDSS was delivered through 4 active electrodes applied to the knee extensors and flexors, plantarflexors, and dorsiflexors, sending a stimulation pulse to each electrode one after another with 90° phase shift between successive electrodes. Isometric ankle torque was measured during fatiguing stimulations using SDSS and conventional single active electrode stimulation lasting 2 minutes. We demonstrated greater fatigue-reducing ability of SDSS compared with the conventional protocol, as revealed by larger values of fatigue index and/or torque peak mean in all muscles except knee flexors of able-bodied individuals, and in all muscles tested in individuals with SCI. Our study has revealed improvements in fatigue tolerance during transcutaneous neuromuscular electrical stimulation using SDSS, a stimulation strategy that alternates activation of subcompartments of muscles. The SDSS protocol can provide greater stimulation times with less decrement in mechanical output compared with the conventional protocol. © The Author(s) 2014.

Hyperexcitability to electrical stimulation and accelerated muscle fatiguability of taut bands in rats.

PubMed

Wang, Yong-Hui; Yin, Ming-Jing; Fan, Zhen-Zhen; Arendt-Nielsen, Lars; Ge, Hong-You; Yue, Shou-Wei

2014-04-01

Myofascial trigger points contribute significantly to musculoskeletal pain and motor dysfunction and may be associated with accelerated muscle fatiguability. The aim of this study was to investigate the electrically induced force and fatigue characteristics of muscle taut bands in rats. Muscle taut bands were dissected out and subjected to trains of electrical stimulation. The electrical threshold intensity for muscle contraction and maximum contraction force (MCF), electrical intensity dependent fatigue and electrical frequency dependent fatigue characteristics were assessed in three different sessions (n=10 each) and compared with non-taut bands in the biceps femoris muscle. The threshold intensity for muscle contraction and MCF at the 10th, 15th and 20th intensity dependent fatigue stimuli of taut bands were significantly lower than those of non-taut bands (all p<0.05). The MCF at the 15th and 20th intensity dependent fatigue stimuli of taut bands were significantly lower than those at the 1st and 5th stimuli (all p<0.01). The MCF in the frequency dependent fatigue test was significantly higher and the stimulus frequency that induced MCF was significantly lower for taut bands than for non-taut bands (both p<0.01). The present study demonstrates that the muscle taut band itself was more excitable to electrical stimulation and significantly less fatigue resistant than normal muscle fibres.

Muscle Fatigue Affects the Interpolated Twitch Technique When Assessed Using Electrically-Induced Contractions in Human and Rat Muscles.

PubMed

Neyroud, Daria; Cheng, Arthur J; Bourdillon, Nicolas; Kayser, Bengt; Place, Nicolas; Westerblad, Håkan

2016-01-01

The interpolated twitch technique (ITT) is the gold standard to assess voluntary activation and central fatigue. Yet, its validity has been questioned. Here we studied how peripheral fatigue can affect the ITT. Repeated contractions at submaximal frequencies were produced by supramaximal electrical stimulations of the human adductor pollicis muscle in vivo and of isolated rat soleus fiber bundles; an extra stimulation pulse was given during contractions to induce a superimposed twitch. Human muscles fatigued by repeated 30-Hz stimulation trains (3 s on-1 s off) showed an ~80% reduction in the superimposed twitch force accompanied by a severely reduced EMG response (M-wave amplitude), which implies action potential failure. Subsequent experiments combined a less intense stimulation protocol (1.5 s on-3 s off) with ischemia to cause muscle fatigue, but which preserved M-wave amplitude. However, the superimposed twitch force still decreased markedly more than the potentiated twitch force; with ITT this would reflect increased "voluntary activation." In contrast, the superimposed twitch force was relatively spared when a similar protocol was performed in rat soleus bundles. Force relaxation was slowed by >150% in fatigued human muscles, whereas it was unchanged in rat soleus bundles. Accordingly, results similar to those in the human muscle were obtained when relaxation was slowed by cooling the rat soleus muscles. In conclusion, our data demonstrate that muscle fatigue can confound the quantification of central fatigue using the ITT.

Reduced servo-control of fatigued human finger extensor and flexor muscles.

PubMed Central

Hagbarth, K E; Bongiovanni, L G; Nordin, M

1995-01-01

1. In healthy human subjects holding the index finger semi-extended at the metacarpophalangeal joint against a moderate load, electromyographic (EMG) activity was recorded from the finger extensor and flexor muscles during different stages of muscle fatigue. The aim was to study the effect of muscle fatigue on the level of background EMG activity and on the reflex responses to torque pulses causing sudden extensor unloadings. Paired comparisons were made between the averaged EMG and finger deflection responses under two conditions: (1) at a stage of fatigue (following a sustained co-contraction) when great effort was required to maintain the finger position, and (2) under non-fatigue conditions while the subject tried to produce similar background EMG levels to those in the corresponding fatigue trials. 2. Both the unloading reflex in the extensor and the concurrent stretch reflex in the flexor were significantly less pronounced and had a longer latency in the fatigue trials. Consequently, the finger deflections had a larger amplitude and were arrested later in the fatigue trials. 3. It is concluded that--with avoidance of 'automatic gain compensation', i.e. reflex modifications attributable to differences in background EMG levels--the servo-like action of the unloading and stretch reflexes is reduced in fatigued finger extensor and flexor muscles. PMID:7562624

A Review of Non-Invasive Techniques to Detect and Predict Localised Muscle Fatigue

PubMed Central

Al-Mulla, Mohamed R.; Sepulveda, Francisco; Colley, Martin

2011-01-01

Muscle fatigue is an established area of research and various types of muscle fatigue have been investigated in order to fully understand the condition. This paper gives an overview of the various non-invasive techniques available for use in automated fatigue detection, such as mechanomyography, electromyography, near-infrared spectroscopy and ultrasound for both isometric and non-isometric contractions. Various signal analysis methods are compared by illustrating their applicability in real-time settings. This paper will be of interest to researchers who wish to select the most appropriate methodology for research on muscle fatigue detection or prediction, or for the development of devices that can be used in, e.g., sports scenarios to improve performance or prevent injury. To date, research on localised muscle fatigue focuses mainly on the clinical side. There is very little research carried out on the implementation of detecting/predicting fatigue using an autonomous system, although recent research on automating the process of localised muscle fatigue detection/prediction shows promising results. PMID:22163810

Inter- and intramuscular differences in training-induced hypertrophy of the quadriceps femoris: association with muscle activation during the first training session.

PubMed

Wakahara, Taku; Ema, Ryoichi; Miyamoto, Naokazu; Kawakami, Yasuo

2017-07-01

The purpose of this study was to examine whether inter- and intramuscular differences in hypertrophy induced by resistance training correspond to differences in muscle activation during the first training session. Eleven young men completed 12 weeks of training intervention for knee extension. Before and after the intervention, T1-weighted magnetic resonance (MR) images were recorded to determine the volume and anatomical cross-sectional area (CSA) along the length of the individual muscles of the quadriceps femoris. The T2-weighted MR images were also acquired before and immediately after the first training session. The T2 was calculated for each pixel within the quadriceps femoris, from which the muscle activation was evaluated as %activated volume and area. The results showed that the %activated volume after the first training session was significantly higher in the vastus intermedius than the vastus medialis. However, the relative change in muscle volume after the training intervention was significantly greater in the rectus femoris than the vasti muscles (vastus lateralis, intermedius and medialis). Within the rectus femoris, both the %activated area and relative increase in CSA were significantly greater in the distal region than the proximal region. In contrast, the %activated area and relative increase in CSA of the vasti were nearly uniform along each muscle. These results suggest that the muscle activation during the first training session is associated with the intramuscular difference in hypertrophy induced by training intervention, but not with the intermuscular difference. © 2015 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

Plantar flexor muscle weakness and fatigue in spastic cerebral palsy patients.

PubMed

Neyroud, Daria; Armand, Stéphane; De Coulon, Geraldo; Sarah R Dias Da Silva; Maffiuletti, Nicola A; Kayser, Bengt; Place, Nicolas

2017-02-01

Patients with cerebral palsy develop an important muscle weakness which might affect the aetiology and extent of exercise-induced neuromuscular fatigue. This study evaluated the aetiology and extent of plantar flexor neuromuscular fatigue in patients with cerebral palsy. Ten patients with cerebral palsy and 10 age- and sex-matched healthy individuals (∼20 years old, 6 females) performed four 30-s maximal isometric plantar flexions interspaced by a resting period of 2-3s to elicit a resting twitch. Maximal voluntary contraction force, voluntary activation level and peak twitch were quantified before and immediately after the fatiguing task. Before fatigue, patients with cerebral palsy were weaker than healthy individuals (341±134N vs. 858±151N, p<0.05) and presented lower voluntary activation (73±19% vs. 90±9%, p<0.05) and peak twitch (100±28N vs. 199±33N, p<0.05). Maximal voluntary contraction force was not significantly reduced in patients with cerebral palsy following the fatiguing task (-10±23%, p>0.05), whereas it decreased by 30±12% (p<0.05) in healthy individuals. Plantar flexor muscles of patients with cerebral palsy were weaker than their healthy peers but showed greater fatigue resistance. Cerebral palsy is a widely defined pathology that is known to result in muscle weakness. The extent and origin of muscle weakness were the topic of several previous investigations; however some discrepant results were reported in the literature regarding how it might affect the development of exercise-induced neuromuscular fatigue. Importantly, most of the studies interested in the assessment of fatigue in patients with cerebral palsy did so with general questionnaires and reported increased levels of fatigue. Yet, exercise-induced neuromuscular fatigue was quantified in just a few studies and it was found that young patients with cerebral palsy might be more fatigue resistant that their peers. Thus, it appears that (i) conflicting results exist regarding

β2-adrenergic stimulation enhances Ca2+ release and contractile properties of skeletal muscles, and counteracts exercise-induced reductions in Na+-K+-ATPase Vmax in trained men.

PubMed

Hostrup, M; Kalsen, A; Ortenblad, N; Juel, C; Mørch, K; Rzeppa, S; Karlsson, S; Backer, V; Bangsbo, J

2014-12-15

The aim of the present study was to examine the effect of β2-adrenergic stimulation on skeletal muscle contractile properties, sarcoplasmic reticulum (SR) rates of Ca(2+) release and uptake, and Na(+)-K(+)-ATPase activity before and after fatiguing exercise in trained men. The study consisted of two experiments (EXP1, n = 10 males, EXP2, n = 20 males), where β2-adrenoceptor agonist (terbutaline) or placebo was randomly administered in double-blinded crossover designs. In EXP1, maximal voluntary isometric contraction (MVC) of m. quadriceps was measured, followed by exercise to fatigue at 120% of maximal oxygen uptake (V̇O2, max ). A muscle biopsy was taken after MVC (non-fatigue) and at time of fatigue. In EXP2, contractile properties of m. quadriceps were measured with electrical stimulations before (non-fatigue) and after two fatiguing 45 s sprints. Non-fatigued MVCs were 6 ± 3 and 6 ± 2% higher (P < 0.05) with terbutaline than placebo in EXP1 and EXP2, respectively. Furthermore, peak twitch force was 11 ± 7% higher (P < 0.01) with terbutaline than placebo at non-fatigue. After sprints, MVC declined (P < 0.05) to the same levels with terbutaline as placebo, whereas peak twitch force was lower (P < 0.05) and half-relaxation time was prolonged (P < 0.05) with terbutaline. Rates of SR Ca(2+) release and uptake at 400 nm [Ca(2+)] were 15 ± 5 and 14 ± 5% (P < 0.05) higher, respectively, with terbutaline than placebo at non-fatigue, but declined (P < 0.05) to similar levels at time of fatigue. Na(+)-K(+)-ATPase activity was unaffected by terbutaline compared with placebo at non-fatigue, but terbutaline counteracted exercise-induced reductions in maximum rate of activity (Vmax) at time of fatigue. In conclusion, increased contractile force induced by β2-adrenergic stimulation is associated with enhanced rate of Ca(2+) release in humans. While β2-adrenergic stimulation elicits positive inotropic and lusitropic effects on non-fatigued m. quadriceps, these effects

Atrophy of the Quadriceps Is Not Isolated to the Vastus Medialis Oblique in Individuals With Patellofemoral Pain.

PubMed

Giles, Lachlan S; Webster, Kate E; McClelland, Jodie A; Cook, Jill

2015-08-01

Cross-sectional. Objectives To determine if quadriceps atrophy was present in people with patellofemoral pain (PFP), and whether the vastus medialis oblique (VMO) was selectively involved. Despite the lack of research investigating individual quadriceps muscle size in individuals with PFP, it has been suggested that selective atrophy of the VMO relative to the vastus lateralis could be associated with PFP. The quadriceps muscle sizes of 35 participants with PFP (22 with unilateral and 13 with bilateral symptoms) and 35 asymptomatic control participants matched for age and sex were measured using real-time ultrasound. The thicknesses of the VMO, vastus lateralis, vastus medialis, rectus femoris, and vastus intermedius were measured. Paired-samples t tests were used to compare muscle thickness between limbs in those with unilateral PFP, and independent t tests were used to compare muscle thickness between groups with and without PFP. Results In those with unilateral PFP, the thickness of all portions of the quadriceps muscle was statistically smaller in the symptomatic compared to the asymptomatic limb: VMO (P = .038), vastus medialis (P<.001), vastus lateralis (P = .005), vastus intermedius (P = .013), and rectus femoris (P = .045). No difference was found in thickness of any of the portions of the quadriceps on the affected side of people with PFP compared to asymptomatic controls: VMO (P = .148), vastus medialis (P = .474), vastus lateralis (P = .122), vastus intermedius (P = .466), and rectus femoris (P = .508). Atrophy of all portions of the quadriceps muscles is present in the affected limb of people with unilateral PFP. There was no atrophy of the quadriceps in individuals with PFP compared to those without pathology. Selective atrophy of the VMO relative to the vastus lateralis was not identified in people with PFP.

Efficacy of pre-exercise low-level laser therapy on isokinetic muscle performance in individuals with type 2 diabetes mellitus: study protocol for a randomized controlled trial

PubMed Central

2014-01-01

Background Type 2 diabetes, also known non-insulin-dependent diabetes, is the most prevalent type of the disease and involves defects in the secretion and action of insulin. The aim of the proposed study is to evaluate the efficacy of pre-exercise low-level laser therapy (LLLT) on muscle performance of the quadriceps femoris in individuals with type 2 diabetes. Methods/Design A double-blind, randomized, controlled clinical trial will be carried out in two treatment phases. In the first phase, quadriceps muscle performance will be evaluated using an isokinetic dynamometer and the levels of creatine kinase and lactate dehydrogenase (biochemical markers of muscle damage) will be determined. The participants will then be allocated to four LLLT groups through a randomization process using opaque envelopes: Group A (4 Joules), Group B (6 Joules), Group C (8 Joules) and Group D (0 Joules; placebo). Following the administration of LLLT, the participants will be submitted to an isokinetic eccentric muscle fatigue protocol involving the quadriceps muscle bilaterally. Muscle performance and biochemical markers of muscle damage will be evaluated again immediately after as well as 24 and 48 hours after the experimental protocol. One week after the last evaluation the second phase will begin, during which Groups A, B and C will receive the LLLT protocol that achieved the best muscle performance in phase 1 for a period of 4 weeks. At the end of this period, muscle performance will be evaluated again. The protocol for this study is registered with the World Health Organization under Universal Trial Number U1111-1146-7109. Discussion The purpose of this randomized clinical trial is to evaluate the efficacy of pre-exercise LLLT on the performance of the quadriceps muscle (peak torque, total muscle work, maximum power and fatigue index – normalized by body mass) in individuals with DM-2. The study will support the practice of evidence-based to the use of LLLT in improving muscle

Efficacy of pre-exercise low-level laser therapy on isokinetic muscle performance in individuals with type 2 diabetes mellitus: study protocol for a randomized controlled trial.

PubMed

Gomes, Cid André Fidelis de Paula; Leal-Junior, Ernesto Cesar Pinto; Biasotto-Gonzalez, Daniela Aparecida; El-Hage, Yasmin; Politti, Fabiano; Gonzalez, Tabajara de Oliveira; Dibai-Filho, Almir Vieira; de Oliveira, Adriano Rodrigues; Frigero, Marcelo; Antonialli, Fernanda Colella; Vanin, Adriane Aver; de Tarso Camillo de Carvalho, Paulo

2014-04-09

Type 2 diabetes, also known non-insulin-dependent diabetes, is the most prevalent type of the disease and involves defects in the secretion and action of insulin. The aim of the proposed study is to evaluate the efficacy of pre-exercise low-level laser therapy (LLLT) on muscle performance of the quadriceps femoris in individuals with type 2 diabetes. A double-blind, randomized, controlled clinical trial will be carried out in two treatment phases. In the first phase, quadriceps muscle performance will be evaluated using an isokinetic dynamometer and the levels of creatine kinase and lactate dehydrogenase (biochemical markers of muscle damage) will be determined. The participants will then be allocated to four LLLT groups through a randomization process using opaque envelopes: Group A (4 Joules), Group B (6 Joules), Group C (8 Joules) and Group D (0 Joules; placebo). Following the administration of LLLT, the participants will be submitted to an isokinetic eccentric muscle fatigue protocol involving the quadriceps muscle bilaterally. Muscle performance and biochemical markers of muscle damage will be evaluated again immediately after as well as 24 and 48 hours after the experimental protocol. One week after the last evaluation the second phase will begin, during which Groups A, B and C will receive the LLLT protocol that achieved the best muscle performance in phase 1 for a period of 4 weeks. At the end of this period, muscle performance will be evaluated again. The protocol for this study is registered with the World Health Organization under Universal Trial Number U1111-1146-7109. The purpose of this randomized clinical trial is to evaluate the efficacy of pre-exercise LLLT on the performance of the quadriceps muscle (peak torque, total muscle work, maximum power and fatigue index - normalized by body mass) in individuals with DM-2. The study will support the practice of evidence-based to the use of LLLT in improving muscle performance in Individuals with DM-2

Subacromial impingement syndrome: An electromyographic study of shoulder girdle muscle fatigue.

PubMed

Alizadehkhaiyat, Omid; Roebuck, Margaret M; Makki, Ahmed T; Frostick, Simon P

2018-02-01

Muscle fatigue affecting glenohumeral and/or scapular muscles is suggested as one of the contributing factors to the development of subacromial impingement syndrome (SAIS). Nonetheless, the fatigability of shoulder girdle muscles in association with the pathomechanics of SAIS has not been reported. This study aimed to measure and compare fatigue progression within the shoulder girdle musculature of patients and healthy controls. 75 participants including 39 patients (20 females; 19 males) and 36 healthy controls (15 females; 21 males) participated in the study. Study evaluated the progression of muscle fatigue in 15 shoulder girdle muscles by means of surface and fine-wire EMG during submaximal contraction of four distinct movements (abduction, flexion, internal and external rotation). Shoulder strength, subjective pain experience (McGill Pain Questionnaire), and psychological status (Hospital Anxiety and Depression Scale) were also assessed. The results were compared between patient and control groups according to the gender. Despite marked fatigue observed in the majority of muscles particularly during flexion and abduction at 90°, overall results indicated a lower tendency of fatigue progression in the impingement group across the tests (p < 0.05 - p < 0.001). Shoulder Strength, pain experience, and psychological status were significantly different between the two groups (P < .05). Lower tendency to fatigue progression in the impingement group can be attributed to the presence of fear avoidance and pain-related muscle inhibition, which in turn lead to adaptations in motor programme to reduce muscle recruitment and activation. The significantly higher levels of pain experience and anxiety/depression in the impingement group further support this proposition. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mechanomyogram for identifying muscle activity and fatigue.

PubMed

Yang, Zhao Feng; Kumar, Dinesh Kant; Arjunan, Sridhar Poosapadi

2009-01-01

Mechanomyogram is the recording of the acoustic activity associated with the muscle contraction. While discovered nearly a decade ago with the intention of providing an alternate to the surface electromyogram, it has not yet been investigated thoroughly and there are no current applications associated with MMG. This paper reports an experimental study of MMG against force of contraction and muscle fatigue during cyclic contraction. The results indicate that there is a relationship between the intensity of the MMG recording and force of contraction. A change in the intensity of MMG is also observed with the onset of muscle fatigue. However, the inter-subject variation is very large. The results also indicate that the spectrum of the MMG is very inconsistent and not a useful feature of the signal.

ACL deficient potential copers and non-copers reveal different isokinetic quadriceps strength profiles in the early stage after injury

PubMed Central

Eitzen, I; Eitzen, TJ; Holm, I; Snyder-Mackler, L; Risberg, MA

2011-01-01

Background Isokinetic muscle strength tests using the peak torque value is the most frequently included quadriceps muscle strength measurement for anterior cruciate ligament (ACL) injured subjects. Aims The purpose of this study was to investigate quadriceps muscle performance during the whole isokinetic curve in ACL deficient subjects classified as potential copers or non-copers, and investigate whether these curve profiles were associated with single-leg hop performance. We hypothesized that quadriceps muscle torque at other knee flexion angles than peak torque would give more information about quadriceps muscle strength deficits. Furthermore, we hypothesized that there would be significant torque differences between potential copers and non-copers, and a significant relationship between angle specific torque values and single-leg hop performance. Study Design Cross-sectional study; Level of evidence, 2 Methods Seventy-six individuals with a complete unilateral ACL rupture within the last 3 months were included. The subjects were classified into potential copers and non-copers according to the criteria from Fitzgerald et al12. Isokinetic quadriceps muscle tests were performed at 60°/sec (Biodex 6000). Mean torque values were calculated for peak torque as well as for specific knee flexion angles. The one-leg hop and the 6 meter timed hop tests were included and symmetry indices were used. Results The peak torque value did not identify the largest quadriceps muscle strength deficit. Rather, these were established at knee flexion angles of less than 40°. There were significant differences in angle specific torque values between potential copers and non-copers (p<0.05). Moderate to strong associations were disclosed between angle specific torque values and single-leg hop performance, but only for non-copers (r≥0.32– 0.58). Conclusions Angle specific quadriceps muscle torque values of less than 40° of knee flexion provide more information on the quadriceps

Is the Sørensen test valid to assess muscle fatigue of the trunk extensor muscles?

PubMed

Demoulin, Christophe; Boyer, Mathieu; Duchateau, Jacques; Grosdent, Stéphanie; Jidovtseff, Boris; Crielaard, Jean-Michel; Vanderthommen, Marc

2016-01-01

Very few studies have quantified the degree of fatigue characterized by the decline in the maximal voluntary contraction (MVC) force of the trunk extensors induced by the widely used Sørensen test. Measure the degree of fatigue of the trunk extensor muscles induced by the Sørensen test. Eighty young healthy subjects were randomly divided into a control group (CG) and an experimental group (EG), each including 50% of the two genders. The EG performed an isometric MVC of the trunk extensors (pre-fatigue test) followed by the Sørensen test, the latter being immediately followed by another MVC (post-fatigue test). The CG performed only the pre- and post-fatigue tests without any exertion in between. The comparison of the pre- and post-fatigue tests revealed a significant (P< 0.05) decrease in MVC force normalized by body mass (-13%) in the EG, whereas a small increase occurred in the CG (+2.7%, P= 0.001). This study shows that the Sørensen test performed until failure in a young healthy population results in a reduced ability of the trunk extensor muscles to generate maximal force, and indicates that this test is valid for the assessment of fatigue in trunk extensor muscles.

A Muscle Fibre Conduction Velocity Tracking ASIC for Local Fatigue Monitoring.

PubMed

Koutsos, Ermis; Cretu, Vlad; Georgiou, Pantelis

2016-12-01

Electromyography analysis can provide information about a muscle's fatigue state by estimating Muscle Fibre Conduction Velocity (MFCV), a measure of the travelling speed of Motor Unit Action Potentials (MUAPs) in muscle tissue. MFCV better represents the physical manifestations of muscle fatigue, compared to the progressive compression of the myoelectic Power Spectral Density, hence it is more suitable for a muscle fatigue tracking system. This paper presents a novel algorithm for the estimation of MFCV using single threshold bit-stream conversion and a dedicated application-specified integrated circuit (ASIC) for its implementation, suitable for a compact, wearable and easy to use muscle fatigue monitor. The presented ASIC is implemented in a commercially available AMS 0.35 [Formula: see text] CMOS technology and utilizes a bit-stream cross-correlator that estimates the conduction velocity of the myoelectric signal in real time. A test group of 20 subjects was used to evaluate the performance of the developed ASIC, achieving good accuracy with an error of only 3.2% compared to Matlab.

Fatigue-enhanced hyperalgesia in response to muscle insult: induction and development occur in a sex-dependent manner

PubMed Central

Gregory, N. S.; Gibson-Corley, K.; Frey-Law, L.; Sluka, K. A.

2014-01-01

Chronic muscle pain affects 20–50% of the population, is more common in women than men, and is associated with increased pain during physical activity and exercise. Muscle fatigue is common in people with chronic muscle pain, occurs in response to exercise and is associated with release of fatigue metabolites. Fatigue metabolites can sensitize muscle nociceptors which could enhance pain with exercise. Using a mouse model we tested whether fatigue of a single muscle, induced by electrical stimulation, resulted in enhanced muscle hyperalgesia and if the enhanced hyperalgesia was more pronounced in female mice. Muscle fatigue was induced in combination with a sub-threshold muscle insult (2 injections of pH 5.0 saline) in male and female mice. We show that male and female mice, fatigued immediately prior to muscle insult in the same muscle, develop similar muscle hyperalgesia 24h later. However, female mice also develop hyperalgesia when muscle fatigue and muscle insult occur in different muscles, and when muscle insult is administered 24 hours after fatigue in the same muscle. Further, hyperalgesia lasts significantly longer in females. Finally, muscle insult with or without muscle fatigue results in minimal inflammatory changes in the muscle itself, and sex differences are not related to estradiol (ovariectomy) or changes in brainstem activity (pNR1). Thus, the current model mimics muscle fatigue-induced enhancement of pain observed in chronic muscle pain conditions in the human population. Interactions between fatigue and muscle insult may underlie the development of chronic widespread pain with an associated female predominance observed in human subjects. PMID:23906552

Quadriceps combined with hip abductor strengthening versus quadriceps strengthening in treating knee osteoarthritis: a study protocol for a randomized controlled trial.

PubMed

Xie, Yujie; Zhang, Chi; Jiang, Wei; Huang, Juan; Xu, Lili; Pang, Guoyin; Tang, Haiyan; Chen, Ruyan; Yu, Jihua; Guo, Shengmin; Xu, Fangyuan; Wang, Jianxiong

2018-05-15

Lower limb strengthening, especially the quadriceps training, is of much necessity for patients with knee osteoarthritis (KOA). Previous studies suggest that strengthening of the hip muscles, especially the hip abductor, can potentially relieve the KOA-associated symptoms. Nevertheless, the effects of quadriceps combined with hip abductor strengthening remain unclear. Therefore, the current randomized controlled trial is designed aiming to observe whether quadriceps in combination with hip abductor strengthening can better improve the function and reduce pain in KOA patients than quadriceps training alone. A total of 80 subjects with symptomatic KOA will be recruited from the communities and hospital outpatient, and will be randomly assigned to the experiment group (Quadriceps-plus-hip-abductor-strengthening) or the control group (Quadriceps-strengthening). Specifically, participants in the experiment group will complete 4 exercises to train the quadriceps and hip abductor twice a day for 6 weeks at home, while those in the control group will only perform 2 exercises to strengthen the quadriceps. Besides, all patients will also receive usual care management, including health education and physical agent therapy when necessary. Knee pain will be measured using the Visual Analogue Scale (VAS) at baseline, in every week during the course of treatment, as well as 8 and 12 weeks after randomization. Furthermore, knee function will be measured using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scale, and the quality of life will be measured using the MOS Item Short-form Health Survey (SF-36). In this study, several simple tests will be applied to assess the objective function. All the assessments except for VAS will be carried out at baseline, and in the 6th, 8th and 12th weeks respectively. Our findings will provide more evidence for the effects of hip abductor strengthening on relieving pain and improving function in KOA patients. Hip

Myoelectric manifestations of jaw elevator muscle fatigue and recovery in healthy and TMD subjects.

PubMed

Castroflorio, T; Falla, D; Tartaglia, G M; Sforza, C; Deregibus, A

2012-09-01

The effects of muscle pain and fatigue on the control of jaw elevator muscles are not well known. Furthermore, the myoelectric manifestations of fatigue and recovery from fatigue in the masticatory muscles are not reported in literature. The main aims of this study were (i) to evaluate the possible use of surface electromyography (sEMG) as an objective measure of fatigue of the jaw elevator muscles, (ii) to compare the myoelectric manifestations of fatigue in the temporalis anterior and masseter muscles bilaterally, (iii) to assess recovery of the investigated muscles after an endurance test and (iv) to compare fatigue and recovery of the jaw elevator muscles in healthy subjects and patients with muscle-related temporomandibular disorders (TMD). The study was performed on twenty healthy volunteers and eighteen patients with muscle-related TMD. An intra-oral compressive-force sensor was used to measure the voluntary contraction forces close to the intercuspal position and to provide visual feedback of submaximal forces to the subject. Surface EMG signals were recorded with linear electrode arrays during isometric contractions at 20%, 40%, 60% and 80% of the maximum voluntary contraction force, during an endurance test and during the recovery phase. The results showed that (i) the slope of the mean power spectral frequency (MNF) and the initial average rectified value (ARV) could be used to monitor fatigue of the jaw elevators, (ii) the temporalis anterior and masseter muscle show the same myoelectric manifestations of fatigue and recovery and (iii) the initial values of MNF and ARV were lower in patients with muscle-related TMD. The assessment of myoelectric manifestations of fatigue in the masticatory muscles may assist in the clinical assessment of TMDs. © 2012 Blackwell Publishing Ltd.

Fatigue of muscles weakened by death of motoneurons.

PubMed

Thomas, Christine K; Zijdewind, Inge

2006-01-01

Weakness is a characteristic of muscles influenced by the postpolio syndrome (PPS), amyotrophic lateral sclerosis (ALS), and spinal cord injury (SCI). The strength deficits relate to changes in muscle use and to the chronic denervation that can follow the spinal motoneuron death common to these disorders. PPS, ALS, and SCI also involve variable amounts of supraspinal neuron death, the effects of which on muscle weakness remains unclear. Nevertheless, weakness of muscle itself defines the functional consequences of these disorders. A weaker muscle requires an individual to work that muscle at higher than usual intensities relative to its maximal capacity, inducing progressive fatigue and an increased sense of effort. Little evidence is available to suggest that the fatigue commonly experienced by individuals with these disorders relates to an increase in the intrinsic fatigability of the muscle fibers. The only exception is when SCI induces chronic muscle paralysis. To reduce long-term functional deficits in these disorders, studies must identify the signaling pathways that influence neuron survival and determine the factors that encourage and limit sprouting of motor axons. This may ensure that a greater proportion of the fibers in each muscle remain innervated and available for use.

The effects of accumulated muscle fatigue on the mechanomyographic waveform: implications for injury prediction.

PubMed

Tosovic, D; Than, C; Brown, J M M

2016-08-01

Muscle fatigue has been identified as a risk factor for spontaneous muscle injuries in sport. However, few studies have investigated the accumulated effects of muscle fatigue on human muscle contractile properties. This study aimed to determine whether repeated bouts of exercise inducing acute fatigue leads to longer-term fatigue-related changes in muscle contractile properties. Maximum voluntary contraction (MVC), electromyographic (EMG) and mechanomyographic (MMG) measures were recorded in the biceps brachii of 11 participants for 13 days, before and after a maximally fatiguing exercise protocol. The exercise protocol involved participants repetitively lifting a weight (concentric contractions only) equal to 40 % MVC, until failure. A significant (p < 0.05) acute pre- to post-exercise decline of biceps brachii MVC and median power frequency (MPF) was observed each day, whilst no difference existed between pre-exercise MVC or MPF values on subsequent days (days 2-13). However, decreases in number of lift repetitions and in pre-exercise MMG values of muscle belly displacement, contraction velocity and half-relaxation velocity were observed through to day 13. Whilst MVC and MPF measures resolved by the following day's test session, MMG measures indicated an ongoing decrement in muscle performance through days 2-13 consistent with the decline in lift repetitions observed. These results suggest that MMG may be more sensitive in detecting accumulated muscle fatigue than the 'gold standard' measures of MVC/MPF. Considering that muscle fatigue leads to injury, the on-going monitoring of MMG derived contractile properties of muscles in athletes may aid in the prediction of fatigued-induced muscle injury.

Changes in the flexion relaxation response induced by lumbar muscle fatigue.

PubMed

Descarreaux, Martin; Lafond, Danik; Jeffrey-Gauthier, Renaud; Centomo, Hugo; Cantin, Vincent

2008-01-24

The flexion relaxation phenomenon (FRP) is an interesting model to study the modulation of lumbar stability. Previous investigations have explored the effect of load, angular velocity and posture on this particular response. However, the influence of muscular fatigue on FRP parameters has not been thoroughly examined. The objective of the study is to identify the effect of erector spinae (ES) muscle fatigue and spine loading on myoelectric silence onset and cessation in healthy individuals during a flexion-extension task. Twenty healthy subjects participated in this study and performed blocks of 3 complete trunk flexions under 4 different experimental conditions: no fatigue/no load (1), no fatigue/load (2), fatigue/no load(3), and fatigue/load (4). Fatigue was induced according to the Sorenson protocol, and electromyographic (EMG) power spectral analysis confirmed that muscular fatigue was adequate in each subject. Trunk and pelvis angles and surface EMG of the ES L2 and L5 were recorded during a flexion-extension task. Trunk flexion angle corresponding to the onset and cessation of myoelectric silence was then compared across the different experimental conditions using 2 x 2 repeated-measures ANOVA. Onset of myoelectric silence during the flexion motion appeared earlier after the fatigue task. Additionally, the cessation of myoelectric silence was observed later during the extension after the fatigue task. Statistical analysis also yielded a main effect of load, indicating a persistence of ES myoelectric activity in flexion during the load condition. The results of this study suggest that the presence of fatigue of the ES muscles modifies the FRP. Superficial back muscle fatigue seems to induce a shift in load-sharing towards passive stabilizing structures. The loss of muscle contribution together with or without laxity in the viscoelastic tissues may have a substantial impact on post fatigue stability.

Electrical Stimulation Frequency and Skeletal Muscle Characteristics: Effects on Force and Fatigue.

PubMed

Vromans, Maria; Faghri, Pouran

2017-12-05

This investigation aimed to determine the force and muscle surface electromyography (EMG) responses to different frequencies of electrical stimulation (ES) in two groups of muscles with different size and fiber composition (fast- and slow-twitch fiber proportions) during a fatigue-inducing protocol. Progression towards fatigue was evaluated in the abductor pollicis brevis (APB) and vastus lateralis (VL) when activated by ES at three frequencies (10, 35, and 50Hz). Ten healthy adults (mean age: 23.2 ± 3.0 years) were recruited; participants signed an IRB approved consent form prior to participation. Protocols were developed to 1) identify initial ES current intensity required to generate the 25% maximal voluntary contraction (MVC) at each ES frequency and 2) evaluate changes in force and EMG activity during ES-induced contraction at each frequency while progressing towards fatigue. For both muscles, stimulation at 10Hz required higher current intensity of ES to generate the initial force. There was a significant decline in force in response to ES-induced fatigue for all frequencies and for both muscles (p<0.05). However, the EMG response was not consistent between muscles. During the progression towards fatigue, the APB displayed an initial drop in force followed by an increase in EMG activity and the VL displayed a decrease in EMG activity for all frequencies. Overall, it appeared that there were some significant interactions between muscle size and fiber composition during progression towards fatigue for different ES frequencies. It could be postulated that muscle characteristics (size and fiber composition) should be considered when evaluating progression towards fatigue as EMG and force responses are not consistent between muscles.

Contribution from motor unit firing adaptations and muscle co-activation during fatigue.

PubMed

Contessa, Paola; Letizi, John; De Luca, Gianluca; Kline, Joshua C

2018-03-14

The control of motor unit firing behavior during fatigue is still debated in the literature. Most studies agree that the central nervous system increases the excitation to the motoneuron pool to compensate for decreased force contributions of individual motor units and sustain muscle force output during fatigue. However, some studies claim that motor units may decrease their firing rates despite increased excitation, contradicting the direct relationship between firing rates and excitation that governs the voluntary control of motor units. To investigate whether the control of motor units in fact changes with fatigue, we measured motor unit firing behavior during repeated contractions of the first dorsal interosseous (FDI) muscle while concurrently monitoring the activation of surrounding muscles - including the flexor carpi radialis, extensor carpi radialis, and pronator teres. Across all subjects, we observed an overall increase in FDI activation and motor unit firing rates by the end of the fatigue task. However, in some subjects we observed increases in FDI activation and motor unit firing rates only during the initial phase of the fatigue task, followed by subsequent decreases during the late phase of the fatigue task while the co-activation of surrounding muscles increased. These findings indicate that the strategy for sustaining force output may occasionally change leading to increases in the relative activation of surrounding muscles while the excitation to the fatiguing muscle decreases. Importantly, irrespective of changes in the strategy for sustaining force output, the control properties regulating motor unit firing behavior remain unchanged during fatigue.

Neuromuscular transmission and muscle fatigue changes by nanostructured oxygen.

PubMed

Ivannikov, Maxim V; Sugimori, Mutsuyuki; Llinás, Rodolfo R

2017-04-01

Oxygen (O 2 ) nanobubbles offer a new method for tissue oxygenation. The effects of O 2 nanobubbles on transmission at neuromuscular junctions (NMJs) and muscle function were explored in murine diaphragm. Electrophysiological parameters, NMJ ultrastructure, muscle force, and muscle fatigue were studied during superfusion with solutions with different oxygen levels or oxygen nanobubbles. High frequency nerve stimulation of muscles superfused with O 2 nanobubble solution slowed neurotransmission decline over those with either control or hyperoxic solution. O 2 nanobubble solution increased the amplitude of evoked end plate potentials and quantal content but did not affect spontaneous activity. Electron microscopy of stimulated O 2 nanobubble treated NMJs showed accumulation of large synaptic vesicles and endosome-like structures. O 2 nanobubble solution had no effects on isometric muscle force, but it significantly decreased fatigability and maximum force recovery time in nerve stimulated muscles. O 2 nanobubbles increase neurotransmission and reduce the probability of neurotransmission failure in muscle fatigue. Muscle Nerve 55: 555-563, 2017. © 2016 Wiley Periodicals, Inc.

Impaired muscle strength may contribute to fatigue in patients with aneurysmal subarachnoid hemorrhage.

PubMed

Harmsen, Wouter J; Ribbers, Gerard M; Zegers, Bart; Sneekes, Emiel M; Praet, Stephan F E; Heijenbrok-Kal, Majanka H; Khajeh, Ladbon; van Kooten, Fop; Neggers, Sebastiaan J C M M; van den Berg-Emons, Rita J

2017-03-01

Patients with aneurysmal subarachnoid hemorrhage (a-SAH) show long-term fatigue and face difficulties in resuming daily physical activities. Impaired muscle strength, especially of the lower extremity, impacts the performance of daily activities and may trigger the onset of fatigue complaints. The present study evaluated knee muscle strength and fatigue in patients with a-SAH. This study included 33 patients, 6 months after a-SAH, and 33 sex-matched and age-matched healthy controls. Isokinetic muscle strength of the knee extensors and flexors was measured at 60 and 180°/s. Maximal voluntary muscle strength was defined as peak torque and measured in Newton-meter. Fatigue was examined using the Fatigue Severity Scale. In patients with a-SAH, the maximal knee extension was 22% (60°/s) and 25% (180°/s) lower and maximal knee flexion was 33% (60°/s) and 36% (180°/s) lower compared with that of matched controls (P≤0.001). The Fatigue Severity Scale score was related to maximal knee extension (60°/s: r=-0.426, P=0.015; 180°/s: r=-0.376, P=0.034) and flexion (60°/s: r=-0.482, P=0.005; 180°/s: r=-0.344, P=0.083). The knee muscle strength was 28-47% lower in fatigued (n=13) and 11-32% lower in nonfatigued (n=20) patients; deficits were larger in fatigued patients (P<0.05), particularly when the muscle strength (peak torque) was measured at 60°/s. The present results indicate that patients with a-SAH have considerably impaired knee muscle strength, which is related to more severe fatigue. The present findings are exploratory, but showed that knee muscle strength may play a role in the severity of fatigue complaints, or vice versa. Interventions targeting fatigue after a-SAH seem necessary and may consider strengthening exercise training in order to treat a debilitating condition.

Positive inotropism in mammalian skeletal muscle in vitro during and after fatigue.

PubMed

Reading, S A; Murrant, C L; Barclay, J K

2004-04-01

We tested the hypothesis that positive inotropic factors decrease fatigue and improve recovery from fatigue in mammalian skeletal muscle in vitro. To induce fatigue, we stimulated mouse soleus and extensor digitorum longus (EDL) to perform isometric tetanic contractions (50 impulses x s(-1) for 0.5 s) at 6 contractions x min(-1) for 60 min in soleus and 3 contractions x min(-1) for 20 min in EDL. Muscles were submerged in Krebs-Henseleit bicarbonate solution (Krebs) at 27 degrees C gassed with 95% nitrogen - 5% carbon dioxide (anoxia). Before and for 67 min after the fatigue period, muscles contracted at 0.6 contractions x min(-1) in 95% oxygen - 5% carbon dioxide (hyperoxia). We added a permeable cAMP analog (N6, 2'-O-dibutyryladenosine 3':5'-cyclic monophosphate at 10(-3) mol x L(-1) (dcAMP)), caffeine (2 x 10(-3) mol x L(-1), or Krebs as vehicle control at 25 min before, during, or at the end of the fatigue period. In soleus and EDL, both challenges added before fatigue significantly increased developed force but only caffeine increased developed force when added during the fatigue period. At the end of fatigue, the decrease in force in challenged muscles was equal to or greater than in controls so that the force remaining was the same or less than in controls. EDL challenged with dcAMP or caffeine at any time recovered more force than controls. In soleus, caffeine improved recovery except when added before fatigue. With dcAMP added to soleus, recovery was better after challenges at 10 min and the end of the fatigue period. Thus, increased intracellular concentrations of cAMP and (or) Ca2+ did not decrease fatigue in either muscle but improved recovery from fatigue in EDL and, in some conditions, in soleus.

Measurement of fatigue in knee flexor and extensor muscles.

PubMed

Kawabata, Y; Senda, M; Oka, T; Yagata, Y; Takahara, Y; Nagashima, H; Inoue, H

2000-04-01

In order to examine fatigue of the knee flexor and extensor muscles and to investigate the characteristics of muscular fatigue in different sports, a Cybex machine was used to measure muscle fatigue and recovery during isokinetic knee flexion and extension. Eighteen baseball players, 12 soccer players and 13 marathon runners were studied. Each subject was tested in the sitting position and made to perform 50 consecutive right knee bends and stretches at maximum strength. This was done 3 times with an interval of 10 min between each series. The peak torque to body weight ratio and the fatigue rate were determined in each case. In all subjects, the peak torque to body weight ratio was higher for extensors than flexors. Over the 3 trials, the fatigue rate of extensors showed little change, while that of flexors had a tendency to increase. In each subject, knee extensors showed a high fatigue rate but a quick recovery, while knee flexors showed a low fatigue rate but a slow recovery. As the marathon runners had the smallest fatigue rates for both flexors and extensors, we concluded that marathon runners had more stamina than baseball players and soccer players.

Predictive model of muscle fatigue after spinal cord injury in humans.

PubMed

Shields, Richard K; Chang, Ya-Ju; Dudley-Javoroski, Shauna; Lin, Cheng-Hsiang

2006-07-01

The fatigability of paralyzed muscle limits its ability to deliver physiological loads to paralyzed extremities during repetitive electrical stimulation. The purposes of this study were to determine the reliability of measuring paralyzed muscle fatigue and to develop a model to predict the temporal changes in muscle fatigue that occur after spinal cord injury (SCI). Thirty-four subjects underwent soleus fatigue testing with a modified Burke electrical stimulation fatigue protocol. The between-day reliability of this protocol was high (intraclass correlation, 0.96). We fit the fatigue index (FI) data to a quadratic-linear segmental polynomial model. FI declined rapidly (0.3854 per year) for the first 1.7 years, and more slowly (0.01 per year) thereafter. The rapid decline of FI immediately after SCI implies that a "window of opportunity" exists for the clinician if the goal is to prevent these changes. Understanding the timing of change in muscle endurance properties (and, therefore, load-generating capacity) after SCI may assist clinicians when developing therapeutic interventions to maintain musculoskeletal integrity.

Muscle- and Mode-Specific Responses of the Forearm Flexors to Fatiguing, Concentric Muscle Actions

PubMed Central

Hill, Ethan; Housh, Terry; Smith, Cory; Schmidt, Richard; Johnson, Glen

2016-01-01

Background: Electromyographic (EMG) and mechanomyographic (MMG) studies of fatigue have generally utilized maximal isometric or dynamic muscle actions, but sport- and work-related activities involve predominately submaximal movements. Therefore, the purpose of the present investigation was to examine the torque, EMG, and MMG responses as a result of submaximal, concentric, isokinetic, forearm flexion muscle actions. Methods: Twelve men performed concentric peak torque (PT) and isometric PT trials before (pretest) and after (posttest) performing 50 submaximal (65% of concentric PT), concentric, isokinetic (60°·s−1), forearm flexion muscle actions. Surface EMG and MMG signals were simultaneously recorded from the biceps brachii and brachioradialis muscles. Results: The results of the present study indicated similar decreases during both the concentric PT and isometric PT measurements for torque, EMG mean power frequency (MPF), and MMG MPF following the fatiguing workbout, but no changes in EMG amplitude (AMP) or MMG AMP. Conclusions: These findings suggest that decreases in torque as a result of fatiguing, dynamic muscle actions may have been due to the effects of metabolic byproducts on excitation–contraction coupling as indicated by the decreases in EMG MPF and MMG MPF, but lack of changes in EMG AMP and MMG AMP from both the biceps brachii and brachioradialis muscles.

Locomotor Muscle Fatigue Does Not Alter Oxygen Uptake Kinetics during High-Intensity Exercise.

PubMed

Hopker, James G; Caporaso, Giuseppe; Azzalin, Andrea; Carpenter, Roger; Marcora, Samuele M

2016-01-01

The [Formula: see text] slow component ([Formula: see text]) that develops during high-intensity aerobic exercise is thought to be strongly associated with locomotor muscle fatigue. We sought to experimentally test this hypothesis by pre-fatiguing the locomotor muscles used during subsequent high-intensity cycling exercise. Over two separate visits, eight healthy male participants were asked to either perform a non-metabolically stressful 100 intermittent drop-jumps protocol (pre-fatigue condition) or rest for 33 min (control condition) according to a random and counterbalanced order. Locomotor muscle fatigue was quantified with 6-s maximal sprints at a fixed pedaling cadence of 90 rev·min -1 . Oxygen kinetics and other responses (heart rate, capillary blood lactate concentration and rating of perceived exertion, RPE) were measured during two subsequent bouts of 6 min cycling exercise at 50% of the delta between the lactate threshold and [Formula: see text] determined during a preliminary incremental exercise test. All tests were performed on the same cycle ergometer. Despite significant locomotor muscle fatigue ( P = 0.03), the [Formula: see text] was not significantly different between the pre-fatigue (464 ± 301 mL·min -1 ) and the control (556 ± 223 mL·min -1 ) condition ( P = 0.50). Blood lactate response was not significantly different between conditions ( P = 0.48) but RPE was significantly higher following the pre-fatiguing exercise protocol compared with the control condition ( P < 0.01) suggesting higher muscle recruitment. These results demonstrate experimentally that locomotor muscle fatigue does not significantly alter the [Formula: see text] kinetic response to high intensity aerobic exercise, and challenge the hypothesis that the [Formula: see text] is strongly associated with locomotor muscle fatigue.

Muscle-Cooling Intervention to Reduce Fatigue and Fatigue-Induced Tremor in Novice and Experienced Surgeons: A Preliminary Investigation.

PubMed

Jensen, Lauren; Dancisak, Michael; Korndorffer, James

2016-10-01

A localized, intermittent muscle-cooling protocol was implemented to determine cooling garment efficacy in reducing upper extremity muscular fatigue and tremor in novice ( n  = 10) and experienced surgeons ( n  = 9). Subjects wore a muscle-cooling garment while performing multiple trials of a forearm exercise and paired suturing task to induce muscular fatigue and exercise-induced tremor. A reduction in tremor amplitude and an extension in time to fatigue were expected with muscle cooling as compared with control trials. Each subject completed an intervention session (5°C cooling condition) and a control session (32°C or thermal neutral condition). A paired samples t test indicated that tremor amplitude was significantly reduced ( t [8] = 1.89458; p  < 0.05) in experienced surgeons in two dimensions (up and down, and back and forth). Tremor amplitude was reduced in novice surgeons but the effect was not significant. Time to fatigue and suture time improved in both cohorts with muscle cooling, but the effect did not reach significance. Results from the pilot work suggest muscle cooling as an intervention for reduction of fatigue and tremor is very promising, warranting further investigation. Surgical specialties that require prolonged procedures might benefit more from this intervention.

Influence of inspiratory resistive loading on expiratory muscle fatigue in healthy humans.

PubMed

Peters, Carli M; Welch, Joseph F; Dominelli, Paolo B; Molgat-Seon, Yannick; Romer, Lee M; McKenzie, Donald C; Sheel, A William

2017-09-01

What is the central question of this study? This study is the first to measure objectively both inspiratory and expiratory muscle fatigue after inspiratory resistive loading to determine whether the expiratory muscles are activated to the point of fatigue when specifically loading the inspiratory muscles. What is the main finding and its importance? The absence of abdominal muscle fatigue suggests that future studies attempting to understand the neural and circulatory consequences of diaphragm fatigue can use inspiratory resistive loading without considering the confounding effects of abdominal muscle fatigue. Expiratory resistive loading elicits inspiratory as well as expiratory muscle fatigue, suggesting parallel coactivation of the inspiratory muscles during expiration. It is unknown whether the expiratory muscles are likewise coactivated to the point of fatigue during inspiratory resistive loading (IRL). The purpose of this study was to determine whether IRL elicits expiratory as well as inspiratory muscle fatigue. Healthy male subjects (n = 9) underwent isocapnic IRL (60% maximal inspiratory pressure, 15 breaths min -1 , 0.7 inspiratory duty cycle) to task failure. Abdominal and diaphragm contractile function was assessed at baseline and at 3, 15 and 30 min post-IRL by measuring gastric twitch pressure (P ga,tw ) and transdiaphragmatic twitch pressure (P di,tw ) in response to potentiated magnetic stimulation of the thoracic and phrenic nerves, respectively. Fatigue was defined as a significant reduction from baseline in P ga,tw or P di,tw . Throughout IRL, there was a time-dependent increase in cardiac frequency and mean arterial blood pressure, suggesting activation of the respiratory muscle metaboreflex. The P di,tw was significantly lower than baseline (34.3 ± 9.6 cmH 2 O) at 3 (23.2 ± 5.7 cmH 2 O, P < 0.001), 15 (24.2 ± 5.1 cmH 2 O, P < 0.001) and 30 min post-IRL (26.3 ± 6.0 cmH 2 O, P < 0.001). The P ga,tw was not significantly

Surface-distributed low-frequency asynchronous stimulation delays fatigue of stimulated muscles.

PubMed

Maneski, Lana Z Popović; Malešević, Nebojša M; Savić, Andrej M; Keller, Thierry; Popović, Dejan B

2013-12-01

One important reason why functional electrical stimulation (FES) has not gained widespread clinical use is the limitation imposed by rapid muscle fatigue due to non-physiological activation of the stimulated muscles. We aimed to show that asynchronous low-pulse-rate (LPR) electrical stimulation applied by multipad surface electrodes greatly postpones the occurrence of muscle fatigue compared with conventional stimulation (high pulse rate, HPR). We compared the produced force vs. time of the forearm muscles responsible for finger flexion in 2 stimulation protocols, LPR (fL = 10 Hz) and HPR (fH = 40 Hz). Surface-distributed low-frequency asynchronous stimulation (sDLFAS) doubles the time interval before the onset of fatigue (104 ± 80%) compared with conventional synchronous stimulation. Combining the performance of multipad electrodes (increased selectivity and facilitated positioning) with sDLFAS (decreased fatigue) can improve many FES applications in both the lower and upper extremities. Copyright © 2013 Wiley Periodicals, Inc.

Evaluation of localized muscle fatigue using power spectral density analysis of the electromyogram

NASA Technical Reports Server (NTRS)

Lafevers, E. V.

1974-01-01

Surface electromyograms (EMGs) taken from three upper torso muscles during a push-pull task were analyzed by a power spectral density technique to determine the operational feasibility of the technique for identifying changes in the EMGs resulting from muscular fatigue. The EMGs were taken from four subjects under two conditions (1) in shirtsleeves and (2) in a pressurized space suit. This study confirmed that frequency analysis of dynamic muscle activity is capable of providing reliable data for many industrial applications where fatigue may be of practical interest. The results showed significant effects of the pressurized space suit on the pattern of shirtsleeve fatigue responses of the muscles. The data also revealed (1) reliable differences between muscles in fatigue-induced responses to various locations in the reach envelope at which the subjects were required to perform the push-pull exercise and (2) the differential sensitivity of muscles to the various reach positions in terms of fatigue-related shifts in EMG power.

Locomotor Muscle Fatigue Does Not Alter Oxygen Uptake Kinetics during High-Intensity Exercise

PubMed Central

Hopker, James G.; Caporaso, Giuseppe; Azzalin, Andrea; Carpenter, Roger; Marcora, Samuele M.

2016-01-01

The V˙O2 slow component (V˙O2sc) that develops during high-intensity aerobic exercise is thought to be strongly associated with locomotor muscle fatigue. We sought to experimentally test this hypothesis by pre-fatiguing the locomotor muscles used during subsequent high-intensity cycling exercise. Over two separate visits, eight healthy male participants were asked to either perform a non-metabolically stressful 100 intermittent drop-jumps protocol (pre-fatigue condition) or rest for 33 min (control condition) according to a random and counterbalanced order. Locomotor muscle fatigue was quantified with 6-s maximal sprints at a fixed pedaling cadence of 90 rev·min−1. Oxygen kinetics and other responses (heart rate, capillary blood lactate concentration and rating of perceived exertion, RPE) were measured during two subsequent bouts of 6 min cycling exercise at 50% of the delta between the lactate threshold and V˙O2max determined during a preliminary incremental exercise test. All tests were performed on the same cycle ergometer. Despite significant locomotor muscle fatigue (P = 0.03), the V˙O2sc was not significantly different between the pre-fatigue (464 ± 301 mL·min−1) and the control (556 ± 223 mL·min−1) condition (P = 0.50). Blood lactate response was not significantly different between conditions (P = 0.48) but RPE was significantly higher following the pre-fatiguing exercise protocol compared with the control condition (P < 0.01) suggesting higher muscle recruitment. These results demonstrate experimentally that locomotor muscle fatigue does not significantly alter the V˙O2 kinetic response to high intensity aerobic exercise, and challenge the hypothesis that the V˙O2sc is strongly associated with locomotor muscle fatigue. PMID:27790156

[Difference analysis of muscle fatigue during the exercises of core stability training].

PubMed

Xiao, Jinzhuang; Sun, Jinli; Wang, Hongrui; Yang, Xincai; Zhao, Jinkui

2017-04-01

The present study was carried out with the surface electromyography signal of subjects during the time when subjects did the exercises of the 6 core stability trainings. We analyzed the different activity level of surface electromyography signal, and finally got various fatigue states of muscles in different exercises. Thirty subjects completed exercises of 6 core stability trainings, which were prone bridge, supine bridge, unilateral bridge (divided into two trainings, i.e. the left and right sides alternatively) and bird-dog (divided into two trainings, i.e. the left and right sides alternatively), respectively. Each exercise was held on for 1 minute and 2 minutes were given to relax between two exercises in this test. We measured both left and right sides of the body's muscles, which included erector spina, external oblique, rectus abdominis, rectus femoris, biceps femoris, anterior tibial and gastrocnemius muscles. We adopted the frequency domain characteristic value of the surface electromyography signal, i.e . median frequency slope to analyze the muscle fatigue in this study. In the present paper, the results exhibit different fatigue degrees of the above muscles during the time when they did the core stability rehabilitation exercises. It could be concluded that supine bridge and unilateral bridge can cause more fatigue on erector spina muscle, prone bridge caused Gastrocnemius muscle much fatigue and there were statistical significant differences ( P <0.05) between prone bridge and other five rehabilitation exercises in the degree of rectus abdominis muscle fatigue. There were no statistical significant differences ( P >0.05) between all the left and right sides of the same-named muscles in the median frequency slope during all the exercises of the six core stability trainings, i.e. the degree which the various kinds of rehabilitation exercises effected the left and right side of the same-named muscle had no statistical significant difference ( P >0

Electrophysiology of Muscle Fatigue in Cardiopulmonary Resuscitation on Manikin Model.

PubMed

Cobo-Vázquez, Carlos; De Blas, Gemma; García-Canas, Pablo; Del Carmen Gasco-García, María

2018-01-01

Cardiopulmonary resuscitation requires the provider to adopt positions that could be dangerous for his or her spine, specifically affecting the muscles and ligaments in the lumbar zone and the scapular spinal muscles. Increased fatigue caused by muscular activity during the resuscitation could produce a loss of quality and efficacy, resulting in compromising resuscitation. The aim of this study was to evaluate the maximum time a rescuer can perform uninterrupted chest compressions correctly without muscle fatigue. This pilot study was performed at Universidad Complutense de Madrid (Spain) with the population recruited following CONSORT 2010 guidelines. From the 25 volunteers, a total of 14 students were excluded because of kyphoscoliosis (4), lumbar muscle pain (1), anti-inflammatory treatment (3), or not reaching 80% of effective chest compressions during the test (6). Muscle activity at the high spinal and lumbar (L5) muscles was assessed using electromyography while students performed continuous chest compressions on a ResusciAnne manikin. The data from force exerted were analyzed according to side and muscle groups using Student's t test for paired samples. The influence of time, muscle group, and side was analyzed by multivariate analyses ( p ≤ .05). At 2 minutes, high spinal muscle activity (right: 50.82 ± 9.95; left: 57.27 ± 20.85 μV/ms) reached the highest values. Activity decreased at 5 and 15 minutes. At 2 minutes, L5 activity (right: 45.82 ± 9.09; left: 48.91 ± 10.02 μV/ms) reached the highest values. After 5 minutes and at 15 minutes, activity decreased. Fatigue occurred bilaterally and time was the most important factor. Fatigue began at 2 minutes. Rescuers exert muscular countervailing forces in order to maintain effective compressions. This imbalance of forces could determine the onset of poor posture, musculoskeletal pain, and long-term injuries in the rescuer.

Fatigue and muscle-tendon stiffness after stretch-shortening cycle and isometric exercise.

PubMed

Toumi, Hechmi; Poumarat, Georges; Best, Thomas M; Martin, Alain; Fairclough, John; Benjamin, Mike

2006-10-01

The purpose of the present study was to compare vertical jump performance after 2 different fatigue protocols. In the first protocol, subjects performed consecutive sets of 10 repetitions of stretch-shortening cycle (SSC) contractions. In the second protocol, successive sets of 10 repetitions of isometric contractions were performed for 10 s with the knee at 90 degrees of flexion. The exercises were stopped when the subjects failed to reach 50% of their maximum voluntary isometric contractions. Maximal isometric force and maximal concentric power were assessed by performing supine leg presses, squat jumps, and drop jumps. Surface EMG was used to determine changes in muscle activation before and after fatigue. In both groups, the fatigue exercises reduced voluntary isometric force, maximal concentric power, and drop jump performance. Kinematic data showed a decrease in knee muscle-tendon stiffness accompanied by a lengthened ground contact time. EMG analysis showed that the squat and drop jumps were performed similarly before and after the fatigue exercise for both groups. Although it was expected that the stiffness would decrease more after SSC than after isometric fatigue (as a result of a greater alteration of the reflex sensitivity SSC), our results showed that both protocols had a similar effect on knee muscle stiffness during jumping exercises. Both fatigue protocols induced muscle fatigue, and the decrease in jump performance was linked to a decrease in the strength and stiffness of the knee extensor muscles.

Fatigue and contraction of slow and fast muscles in hypokinetic/hypodynamic rats

NASA Technical Reports Server (NTRS)

Fell, R. D.; Gladden, L. B.; Steffen, J. M.; Musacchia, X. J.

1985-01-01

The effects of hypokinesia/hypodynamia (H/H) on the fatigability and contractile properties of the rat soleus (S) and gastrocnemius (G) muscles have been investigated experimentally. Whole body suspension for one week was used to induce H/H, and fatigue was brought on by train stimulation for periods of 45 and 16 minutes. Following stimulation, rapid rates of fatigue were observed in the G-muscles of the suspended rats, while minimal fatigue was observed in the S-muscles. The twitch and tetanic contractile properties of the muscles were measured before and after train stimulation. It is found that H/H suspension increased twitch tension in the G-muscles, but did not change any contractile properties in the S-muscles. The peak twitch, train, tetanic tensions and time to peak were unchanged in the S-muscles of the suspended rats. On the basis of the experimental results, it is concluded that 1 wk of muscle atropy induced by H/H significantly increases fatigability in G-muscles, but does not affect the contractile properties of fast-twitch and slow-twitch muscles.

Testing of motor unit synchronization model for localized muscle fatigue.

PubMed

Naik, Ganesh R; Kumar, Dinesh K; Yadav, Vivek; Wheeler, Katherine; Arjunan, Sridhar

2009-01-01

Spectral compression of surface electromyogram (sEMG) is associated with onset of localized muscle fatigue. The spectral compression has been explained based on motor unit synchronization theory. According to this theory, motor units are pseudo randomly excited during muscle contraction, and with the onset of muscle fatigue the recruitment pattern changes such that motor unit firings become more synchronized. While this is widely accepted, there is little experimental proof of this phenomenon. This paper has used source dependence measures developed in research related to independent component analysis (ICA) to test this theory.

Muscle fatigue examined at different temperatures in experiments on intact mammalian (rat) muscle fibers.

PubMed

Roots, H; Ball, G; Talbot-Ponsonby, J; King, M; McBeath, K; Ranatunga, K W

2009-02-01

In experiments on small bundles of intact fibers from a rat fast muscle, in vitro, we examined the decline in force in repeated tetanic contractions; the aim was to characterize the effect of shortening and of temperature on the initial phase of muscle fatigue. Short tetanic contractions were elicited at a control repetition rate of 1/60 s, and fatigue was induced by raising the rate to 1/5 s for 2-3 min, both in isometric mode (no shortening) and in shortening mode, in which each tetanic contraction included a ramp shortening at a standard velocity. In experiments at 20 degrees C (n = 12), the force decline during a fatigue run was 25% in the isometric mode but was significantly higher (35%) in the shortening mode. In experiments at different temperatures (10-30 degrees C, n = 11), the tetanic frequency and duration were adjusted as appropriate, and for shortening mode, the velocity was adjusted for maximum power output. In isometric mode, fatigue of force was significantly less at 30 degrees C ( approximately 20%) than at 10 degrees C ( approximately 30%); the power output (force x velocity) was >10x higher at 30 degrees C than at 10 degrees C, and power decline during a fatigue run was less at 30 degrees C ( approximately 20-30%) than at 10 degrees C ( approximately 50%). The finding that the extent of fatigue is increased with shortening contractions and is lower at higher temperatures is consistent with the view that force depression by inorganic phosphate, which accumulates within fibers during activity, may be a primary cause of initial muscle fatigue.

Effectiveness of the Wavelet Transform on the Surface EMG to Understand the Muscle Fatigue During Walk

NASA Astrophysics Data System (ADS)

Hussain, M. S.; Mamun, Md.

2012-01-01

Muscle fatigue is the decline in ability of a muscle to create force. Electromyography (EMG) is a medical technique for measuring muscle response to nervous stimulation. During a sustained muscle contraction, the power spectrum of the EMG shifts towards lower frequencies. These effects are due to muscle fatigue. Muscle fatigue is often a result of unhealthy work practice. In this research, the effectiveness of the wavelet transform applied to the surface EMG (SEMG) signal as a means of understanding muscle fatigue during walk is presented. Power spectrum and bispectrum analysis on the EMG signal getting from right rectus femoris muscle is executed utilizing various wavelet functions (WFs). It is possible to recognize muscle fatigue appreciably with the proper choice of the WF. The outcome proves that the most momentous changes in the EMG power spectrum are symbolized by WF Daubechies45. Moreover, this research has compared bispectrum properties to the other WFs. To determine muscle fatigue during gait, Daubechies45 is used in this research to analyze the SEMG signal.

Functional electrical stimulation to the abdominal wall muscles synchronized with the expiratory flow does not induce muscle fatigue.

PubMed

Okuno, Yukako; Takahashi, Ryoichi; Sewa, Yoko; Ohse, Hirotaka; Imura, Shigeyuki; Tomita, Kazuhide

2017-03-01

[Purpose] Continuous electrical stimulation of abdominal wall muscles is known to induce mild muscle fatigue. However, it is not clear whether this is also true for functional electrical stimulation delivered only during the expiratory phase of breathing. This study aimed to examine whether or not intermittent electrical stimulation delivered to abdominal wall muscles induces muscle fatigue. [Subjects and Methods] The subjects were nine healthy adults. Abdominal electrical stimulation was applied for 1.5 seconds from the start of expiration and then turned off during inspiration. The electrodes were attached to both sides of the abdomen at the lower margin of the 12th rib. Abdominal electrical stimulation was delivered for 15 minutes with the subject in a seated position. Expiratory flow was measured during stimulus. Trunk flexor torque and electromyography activity were measured to evaluate abdominal muscle fatigue. [Results] The mean stimulation on/off ratio was 1:2.3. The declining rate of abdominal muscle torque was 61.1 ± 19.1% before stimulus and 56.5 ± 20.9% after stimulus, not significantly different. The declining rate of mean power frequency was 47.8 ± 11.7% before stimulus and 47.9 ± 10.2% after stimulus, not significantly different. [Conclusion] It was found that intermittent electrical stimulation to abdominal muscles synchronized with the expiratory would not induce muscle fatigue.

Muscle mass as a target to reduce fatigue in patients with advanced cancer.

PubMed

Neefjes, Elisabeth C W; van den Hurk, Renske M; Blauwhoff-Buskermolen, Susanne; van der Vorst, Maurice J D L; Becker-Commissaris, Annemarie; de van der Schueren, Marian A E; Buffart, Laurien M; Verheul, Henk M W

2017-08-01

Cancer-related fatigue (CRF) reduces quality of life and the activity level of patients with cancer. Cancer related fatigue can be reduced by exercise interventions that may concurrently increase muscle mass. We hypothesized that low muscle mass is directly related to higher CRF. A total of 233 patients with advanced cancer starting palliative chemotherapy for lung, colorectal, breast, or prostate cancer were studied. The skeletal muscle index (SMI) was calculated as the patient's muscle mass on level L3 or T4 of a computed tomography scan, adjusted for height. Fatigue was assessed with the Functional Assessment of Chronic Illness Therapy-fatigue questionnaire (cut-off for fatigue <34). Multiple linear regression analyses were conducted to study the association between SMI and CRF adjusting for relevant confounders. In this group of patients with advanced cancer, the median fatigue score was 36 (interquartile range 26-44). A higher SMI on level L3 was significantly associated with less CRF for men (B 0.447, P 0.004) but not for women (B - 0.401, P 0.090). No association between SMI on level T4 and the Functional Assessment of Chronic Illness Therapy-fatigue score was found (n = 82). The association between SMI and CRF may lead to the suggestion that male patients may be able to reduce fatigue by exercise interventions aiming at an increased muscle mass. In women with advanced cancer, CRF is more influenced by other causes, because it is not significantly related to muscle mass. To further reduce CRF in both men and women with cancer, multifactorial assessments need to be performed in order to develop effective treatment strategies. © 2017 The Authors. Journal of Cachexia, Sarcopenia and Muscle published by John Wiley & Sons Ltd on behalf of the Society on Sarcopenia, Cachexia and Wasting Disorders.

Increased susceptibility to fatigue of slow- and fast-twitch muscles from mice lacking the MG29 gene.

PubMed

Nagaraj, R Y; Nosek, C M; Brotto, M A; Nishi, M; Takeshima, H; Nosek, T M; Ma, J

2000-11-09

Mitsugumin 29 (MG29), a major protein component of the triad junction in skeletal muscle, has been identified to play roles in the formation of precise junctional membrane structures important for efficient signal conversion in excitation-contraction (E-C) coupling. We carried out several experiments to not only study the role of MG29 in normal muscle contraction but also to determine its role in muscle fatigue. We compared the in vitro contractile properties of three muscles types, extensor digitorum longus (EDL) (fast-twitch muscle), soleus (SOL) (slow-twitch muscle), and diaphragm (DPH) (mixed-fiber muscle), isolated from mice lacking the MG29 gene and wild-type mice prior to and after fatigue. Our results indicate that the mutant EDL and SOL muscles, but not DPH, are more susceptible to fatigue than the wild-type muscles. The mutant muscles not only fatigued to a greater extent but also recovered significantly less than the wild-type muscles. Following fatigue, the mutant EDL and SOL muscles produced lower twitch forces than the wild-type muscles; in addition, fatiguing produced a downward shift in the force-frequency relationship in the mutant mice compared with the wild-type controls. Our results indicate that fatiguing affects the E-C components of the mutant EDL and SOL muscles, and the effect of fatigue in these mutant muscles could be primarily due to an alteration in the intracellular Ca homeostasis.

Evoked EMG-based torque prediction under muscle fatigue in implanted neural stimulation

NASA Astrophysics Data System (ADS)

Hayashibe, Mitsuhiro; Zhang, Qin; Guiraud, David; Fattal, Charles

2011-10-01

In patients with complete spinal cord injury, fatigue occurs rapidly and there is no proprioceptive feedback regarding the current muscle condition. Therefore, it is essential to monitor the muscle state and assess the expected muscle response to improve the current FES system toward adaptive force/torque control in the presence of muscle fatigue. Our team implanted neural and epimysial electrodes in a complete paraplegic patient in 1999. We carried out a case study, in the specific case of implanted stimulation, in order to verify the corresponding torque prediction based on stimulus evoked EMG (eEMG) when muscle fatigue is occurring during electrical stimulation. Indeed, in implanted stimulation, the relationship between stimulation parameters and output torques is more stable than external stimulation in which the electrode location strongly affects the quality of the recruitment. Thus, the assumption that changes in the stimulation-torque relationship would be mainly due to muscle fatigue can be made reasonably. The eEMG was proved to be correlated to the generated torque during the continuous stimulation while the frequency of eEMG also decreased during fatigue. The median frequency showed a similar variation trend to the mean absolute value of eEMG. Torque prediction during fatigue-inducing tests was performed based on eEMG in model cross-validation where the model was identified using recruitment test data. The torque prediction, apart from the potentiation period, showed acceptable tracking performances that would enable us to perform adaptive closed-loop control through implanted neural stimulation in the future.

C60 fullerene as promising therapeutic agent for correcting and preventing skeletal muscle fatigue.

PubMed

Prylutskyy, Yurij I; Vereshchaka, Inna V; Maznychenko, Andriy V; Bulgakova, Nataliya V; Gonchar, Olga O; Kyzyma, Olena A; Ritter, Uwe; Scharff, Peter; Tomiak, Tomasz; Nozdrenko, Dmytro M; Mishchenko, Iryna V; Kostyukov, Alexander I

2017-01-13

Bioactive soluble carbon nanostructures, such as the C 60 fullerene can bond with up to six electrons, thus serving by a powerful scavenger of reactive oxygen species similarly to many natural antioxidants, widely used to decrease the muscle fatigue effects. The aim of the study is to define action of the pristine C 60 fullerene aqueous colloid solution (C 60 FAS), on the post-fatigue recovering of m. triceps surae in anaesthetized rats. During fatigue development, we observed decrease in the muscle effort level before C 60 FAS administration. After the application of C 60 FAS, a slower effort decrease, followed by the prolonged retention of a certain level, was recorded. An analysis of the metabolic process changes accompanying muscle fatigue showed an increase in the oxidative stress markers H 2 O 2 (hydrogen peroxide) and TBARS (thiobarbituric acid reactive substances) in relation to the intact muscles. After C 60 FAS administration, the TBARS content and H 2 O 2 level were decreased. The endogenous antioxidant system demonstrated a similar effect because the GSH (reduced glutathione) in the muscles and the CAT (catalase) enzyme activity were increased during fatigue. C 60 FAS leads to reduction in the recovery time of the muscle contraction force and to increase in the time of active muscle functioning before appearance of steady fatigue effects. Therefore, it is possible that C 60 FAS affects the prooxidant-antioxidant muscle tissue homeostasis, subsequently increasing muscle endurance.

Computation and evaluation of features of surface electromyogram to identify the force of muscle contraction and muscle fatigue.

PubMed

Arjunan, Sridhar P; Kumar, Dinesh K; Naik, Ganesh

2014-01-01

The relationship between force of muscle contraction and muscle fatigue with six different features of surface electromyogram (sEMG) was determined by conducting experiments on thirty-five volunteers. The participants performed isometric contractions at 50%, 75%, and 100% of their maximum voluntary contraction (MVC). Six features were considered in this study: normalised spectral index (NSM5), median frequency, root mean square, waveform length, normalised root mean square (NRMS), and increase in synchronization (IIS) index. Analysis of variance (ANOVA) and linear regression analysis were performed to determine the significance of the feature with respect to the three factors: muscle force, muscle fatigue, and subject. The results show that IIS index of sEMG had the highest correlation with muscle fatigue and the relationship was statistically significant (P < 0.01), while NSM5 associated best with level of muscle contraction (%MVC) (P < 0.01). Both of these features were not affected by the intersubject variations (P > 0.05).

Computation and Evaluation of Features of Surface Electromyogram to Identify the Force of Muscle Contraction and Muscle Fatigue

PubMed Central

Arjunan, Sridhar P.; Kumar, Dinesh K.; Naik, Ganesh

2014-01-01

The relationship between force of muscle contraction and muscle fatigue with six different features of surface electromyogram (sEMG) was determined by conducting experiments on thirty-five volunteers. The participants performed isometric contractions at 50%, 75%, and 100% of their maximum voluntary contraction (MVC). Six features were considered in this study: normalised spectral index (NSM5), median frequency, root mean square, waveform length, normalised root mean square (NRMS), and increase in synchronization (IIS) index. Analysis of variance (ANOVA) and linear regression analysis were performed to determine the significance of the feature with respect to the three factors: muscle force, muscle fatigue, and subject. The results show that IIS index of sEMG had the highest correlation with muscle fatigue and the relationship was statistically significant (P < 0.01), while NSM5 associated best with level of muscle contraction (%MVC) (P < 0.01). Both of these features were not affected by the intersubject variations (P > 0.05). PMID:24995275

Alternating activation is related to fatigue in lumbar muscles during sustained sitting.

PubMed

Ringheim, Inge; Indahl, Aage; Roeleveld, Karin

2014-06-01

The aim of this study was to investigate the relation between variability in muscle activity and fatigue during a sustained low level contraction in the lumbar muscles. Twenty-five healthy participants (13 men 12 women) performed a 30min sitting task with 5 degrees inclination of the trunk. Surface electromyographic (EMG) signals were recorded bilaterally from the lumbar muscles with 2 high density surface EMG grids of 9×14 electrodes. Median frequency (MDF) decrease, amplitude (RMS) increase and the rating of perceived exertion (RPE) were used as fatigue indices. Alternating activation and spatial and temporal variability were computed and relations with the fatigue indices were explored. During sitting, the mono- and bipolar RMS slightly increased while the MDF remained unchanged indicating no systematic muscle fatigue, although the average RPE increased from 6 to 13 on a scale ranging between 6 and 20. Higher frequency of alternating activation between the left and right side was associated with increased RPE (p=0.03) and decreased MDF (p=0.05). A tendency in the same direction was seen between increased spatial and temporal variation within the grids and increased RPE and decreased MDF. Present findings provide evidence for a relationship between variability in muscle activity and fatigue. Copyright © 2014 Elsevier Ltd. All rights reserved.

Exposure to microgravity for 30 days onboard Bion M1 caused muscle atrophy and impaired regeneration in murine femoral Quadriceps

NASA Astrophysics Data System (ADS)

Radugina, E. A.; Almeida, E. A. C.; Blaber, E.; Poplinskaya, V. A.; Markitantova, Y. V.; Grigoryan, E. N.

2018-02-01

Mechanical unloading in microgravity during spaceflight is known to cause muscular atrophy, changes in muscle fiber composition, gene expression, and reduction in regenerative muscle growth. Although some limited data exists for long-term effects of microgravity in human muscle, these processes have mostly been studied in rodents for short periods of time. Here we report on how long-term (30-day long) mechanical unloading in microgravity affects murine muscles of the femoral Quadriceps group. To conduct these studies we used muscle tissue from 6 microgravity mice, in comparison to habitat (7), and vivarium (14) ground control mice from the NASA Biospecimen Sharing Program conducted in collaboration with the Institute for Biomedical Problems of the Russian Academy of Sciences, during the Russian Bion M1 biosatellite mission in 2013. Muscle histomorphology from microgravity specimens showed signs of extensive atrophy and regenerative hypoplasia relative to ground controls. Specifically, we observed a two-fold decrease in the number of myonuclei, compared to vivarium and ground controls, and central location of myonuclei, low density of myofibers in the tissue, and of myofibrils within a fiber, as well as fragmentation and swelling of myofibers. Despite obvious atrophy, muscle regeneration nevertheless appeared to have continued after 30 days in microgravity as evidenced by thin and short newly formed myofibers. Many of them, however, showed evidence of apoptotic cells and myofibril degradation, suggesting that long-term unloading in microgravity may affect late stages of myofiber differentiation. Ground asynchronous and vivarium control animals demonstrated normal, well-developed tissue structure with sufficient blood and nerve supply and evidence of regenerative formation of new myofibers free of apoptotic nuclei. Regenerative activity of satellite cells in muscles was observed both in microgravity and ground control groups, using Pax7 and Myogenin

Effects of contraction duration on low-frequency fatigue in voluntary and electrically induced exercise of quadriceps muscle in humans.

PubMed

Ratkevicius, A; Skurvydas, A; Povilonis, E; Quistorff, B; Lexell, J

1998-04-01

The aims of this study were to investigate if low-frequency fatigue (LFF) dependent on the duration of repeated muscle contractions and to compare LFF in voluntary and electrically induced exercise. Male subjects performed three 9-min periods of repeated isometric knee extensions at 40% maximal voluntary contraction with contraction plus relaxation periods of 30 plus 60 s, 15 plus 30 s and 5 plus 10 s in protocols 1, 2 and 3, respectively. The same exercise protocols were repeated using feedback-controlled electrical stimulation at 40% maximal tetanic torque. Before and 15 min after each exercise period, knee extension torque at 1, 7, 10, 15, 20, 50 and 100 Hz was assessed. During voluntary exercise, electromyogram root mean square (EMGrms) of the vastus lateralis muscle was evaluated. The 20-Hz torque:100-Hz torque (20:100 Hz torque) ratio was reduced more after electrically induced than after voluntary exercise (P < 0.05). During electrically induced exercise, the decrease in 20:100 Hz torque ratio was gradually (P < 0.05) reduced as the individual contractions shortened. During voluntary exercise, the decrease in 20:100 Hz torque ratio and the increase in EMGrms were greater in protocol 1 (P < 0.01) than in protocols 2 and 3, which did not differ from each other. In conclusion, our results showed that LFF is dependent on the duration of individual muscle contractions during repetitive isometric exercise and that the electrically induced exercise produced a more pronounced LFF compared to voluntary exercise of submaximal intensity. It is suggested that compensatory recruitment of faster-contracting motor units is an additional factor affecting the severity of LFF during voluntary exercise.

Overexpression of antioxidant enzymes in diaphragm muscle does not alter contraction-induced fatigue or recovery

PubMed Central

McClung, Joseph M.; DeRuisseau, Keith C.; Whidden, Melissa A.; Van Remmen, Holly; Richardson, Arlan; Song, Wook; Vrabas, Ioannis S.; Powers, Scott K.

2010-01-01

Low levels of reactive oxygen species (ROS) production are necessary to optimize muscle force production in unfatigued muscle. In contrast, sustained high levels of ROS production have been linked to impaired muscle force production and contraction-induced skeletal muscle fatigue. Using genetically engineered mice, we tested the hypothesis that the independent transgenic overexpression of catalase (CAT), copper/zinc superoxide dismutase (CuZnSOD; SOD1) or manganese superoxide dismutase (MnSOD; SOD2) antioxidant enzymes would negatively affect force production in unfatigued diaphragm muscle but would delay the development of muscle fatigue and enhance force recovery after fatiguing contractions. Diaphragm muscle from wild-type littermates (WT) and from CAT, SOD1 and SOD2 overexpressing mice were subjected to an in vitro contractile protocol to investigate the force–frequency characteristics, the fatigue properties and the time course of recovery from fatigue. The CAT, SOD1 and SOD2 overexpressors produced less specific force (in N cm−2) at stimulation frequencies of 20–300 Hz and produced lower maximal tetanic force than WT littermates. The relative development of muscle fatigue and recovery from fatigue were not influenced by transgenic overexpression of any antioxidant enzyme. Morphologically, the mean cross-sectional area (in μm2) of diaphragm myofibres expressing myosin heavy chain type IIA was decreased in both CAT and SOD2 transgenic animals, and the percentage of non-contractile tissue increased in diaphragms from all transgenic mice. In conclusion, our results do not support the hypothesis that overexpression of independent antioxidant enzymes protects diaphragm muscle from contraction-induced fatigue or improves recovery from fatigue. Moreover, our data are consistent with the concept that a basal level of ROS is important to optimize muscle force production, since transgenic overexpression of major cellular antioxidants is associated with

Potential of M-Wave Elicited by Double Pulse for Muscle Fatigue Evaluation in Intermittent Muscle Activation by Functional Electrical Stimulation for Motor Rehabilitation

PubMed Central

Miura, Naoto; Watanabe, Takashi

2016-01-01

Clinical studies on application of functional electrical stimulation (FES) to motor rehabilitation have been increasing. However, muscle fatigue appears early in the course of repetitive movement production training by FES. Although M-wave variables were suggested to be reliable indices of muscle fatigue in long lasting constant electrical stimulation under the isometric condition, the ability of M-wave needs more studies under intermittent stimulation condition, because the intervals between electrical stimulations help recovery of muscle activation level. In this paper, M-waves elicited by double pulses were examined in muscle fatigue evaluation during repetitive movements considering rehabilitation training with surface electrical stimulation. M-waves were measured under the two conditions of repetitive stimulation: knee extension force production under the isometric condition and the dynamic movement condition by knee joint angle control. Amplitude of M-wave elicited by the 2nd pulse of a double pulse decreased during muscle fatigue in both measurement conditions, while the change in M-waves elicited by single pulses in a stimulation burst was not relevant to muscle fatigue in repeated activation with stimulation interval of 1 s. Fatigue index obtained from M-waves elicited by 2nd pulses was suggested to provide good estimation of muscle fatigue during repetitive movements with FES. PMID:27110556

Fatigue-related firing of distal muscle nociceptors reduces voluntary activation of proximal muscles of the same limb.

PubMed

Kennedy, David S; McNeil, Chris J; Gandevia, Simon C; Taylor, Janet L

2014-02-15

With fatiguing exercise, firing of group III/IV muscle afferents reduces voluntary activation and force of the exercised muscles. These afferents can also act across agonist/antagonist pairs, reducing voluntary activation and force in nonfatigued muscles. We hypothesized that maintained firing of group III/IV muscle afferents after a fatiguing adductor pollicis (AP) contraction would decrease voluntary activation and force of AP and ipsilateral elbow flexors. In two experiments (n = 10) we examined voluntary activation of AP and elbow flexors by measuring changes in superimposed twitches evoked by ulnar nerve stimulation and transcranial magnetic stimulation of the motor cortex, respectively. Inflation of a sphygmomanometer cuff after a 2-min AP maximal voluntary contraction (MVC) blocked circulation of the hand for 2 min and maintained firing of group III/IV muscle afferents. After a 2-min AP MVC, maximal AP voluntary activation was lower with than without ischemia (56.2 ± 17.7% vs. 76.3 ± 14.6%; mean ± SD; P < 0.05) as was force (40.3 ± 12.8% vs. 57.1 ± 13.8% peak MVC; P < 0.05). Likewise, after a 2-min AP MVC, elbow flexion voluntary activation was lower with than without ischemia (88.3 ± 7.5% vs. 93.6 ± 3.9%; P < 0.05) as was torque (80.2 ± 4.6% vs. 86.6 ± 1.0% peak MVC; P < 0.05). Pain during ischemia was reported as Moderate to Very Strong. Postfatigue firing of group III/IV muscle afferents from the hand decreased voluntary drive and force of AP. Moreover, this effect decreased voluntary drive and torque of proximal unfatigued muscles, the elbow flexors. Fatigue-sensitive group III/IV muscle nociceptors act to limit voluntary drive not only to fatigued muscles but also to unfatigued muscles within the same limb.

Disruption of quadriceps tendon after total knee arthroplasty: Case report of four cases.

PubMed

Soong, J W; Silva, A N; Andrew, Tan Hc

2017-01-01

Quadriceps tendon rupture after total knee arthroplasty (TKA) is a rare but dire complication. It is associated with adverse outcomes and morbidities. Studies on such complications are scarce in the literature. In this study, we share our experience in the management of four patients who sustained quadriceps tendon rupture in the early postoperative period. Efforts should be focused on prevention. Meticulous surgical techniques during the medial parapatellar approach to preserve the integrity of quadriceps can reduce the risk of rupture. The importance of prompt diagnosis is emphasized as delayed treatment may lead to poor outcomes. However, making a diagnosis can be challenging, as worsening of the quadriceps strength after TKA is expected because of the surgical approach that violates the quadriceps muscle. In an event of postoperative trauma with resultant extensor weakness, an ultrasound evaluation to exclude a quadriceps tendon rupture should be promptly performed after a fracture is excluded.

Ischemia causes muscle fatigue

NASA Technical Reports Server (NTRS)

Murthy, G.; Hargens, A. R.; Lehman, S.; Rempel, D. M.

2001-01-01

The purpose of this investigation was to determine whether ischemia, which reduces oxygenation in the extensor carpi radialis (ECR) muscle, causes a reduction in muscle force production. In eight subjects, muscle oxygenation (TO2) of the right ECR was measured noninvasively and continuously using near infrared spectroscopy (NIRS) while muscle twitch force was elicited by transcutaneous electrical stimulation (1 Hz, 0.1 ms). Baseline measurements of blood volume, muscle oxygenation and twitch force were recorded continuously, then a tourniquet on the upper arm was inflated to one of five different pressure levels: 20, 40, 60 mm Hg (randomized order) and diastolic (69 +/- 9.8 mm Hg) and systolic (106 +/- 12.8 mm Hg) blood pressures. Each pressure level was maintained for 3-5 min, and was followed by a recovery period sufficient to allow measurements to return to baseline. For each respective tourniquet pressure level, mean TO2 decreased from resting baseline (100% TO2) to 99 +/- 1.2% (SEM), 96 +/- 1.9%, 93 +/- 2.8%, 90 +/- 2.5%, and 86 +/- 2.7%, and mean twitch force decreased from resting baseline (100% force) to 99 +/- 0.7% (SEM), 96 +/- 2.7%, 93 +/- 3.1%, 88 +/- 3.2%, and 86 +/- 2.6%. Muscle oxygenation and twitch force at 60 mm Hg tourniquet compression and above were significantly lower (P < 0.05) than baseline value. Reduced twitch force was correlated in a dose-dependent manner with reduced muscle oxygenation (r = 0.78, P < 0.001). Although the correlation does not prove causation, the results indicate that ischemia leading to a 7% or greater reduction in muscle oxygenation causes decreased muscle force production in the forearm extensor muscle. Thus, ischemia associated with a modest decline in TO2 causes muscle fatigue.

The compensatory interaction between motor unit firing behavior and muscle force during fatigue

PubMed Central

De Luca, Carlo J.; Kline, Joshua C.

2016-01-01

Throughout the literature, different observations of motor unit firing behavior during muscle fatigue have been reported and explained with varieties of conjectures. The disagreement amongst previous studies has resulted, in part, from the limited number of available motor units and from the misleading practice of grouping motor unit data across different subjects, contractions, and force levels. To establish a more clear understanding of motor unit control during fatigue, we investigated the firing behavior of motor units from the vastus lateralis muscle of individual subjects during a fatigue protocol of repeated voluntary constant force isometric contractions. Surface electromyographic decomposition technology provided the firings of 1,890 motor unit firing trains. These data revealed that to sustain the contraction force as the muscle fatigued, the following occurred: 1) motor unit firing rates increased; 2) new motor units were recruited; and 3) motor unit recruitment thresholds decreased. Although the degree of these adaptations was subject specific, the behavior was consistent in all subjects. When we compared our empirical observations with those obtained from simulation, we found that the fatigue-induced changes in motor unit firing behavior can be explained by increasing excitation to the motoneuron pool that compensates for the fatigue-induced decrease in muscle force twitch reported in empirical studies. Yet, the fundamental motor unit control scheme remains invariant throughout the development of fatigue. These findings indicate that the central nervous system regulates motor unit firing behavior by adjusting the operating point of the excitation to the motoneuron pool to sustain the contraction force as the muscle fatigues. PMID:27385798

The compensatory interaction between motor unit firing behavior and muscle force during fatigue.

PubMed

Contessa, Paola; De Luca, Carlo J; Kline, Joshua C

2016-10-01

Throughout the literature, different observations of motor unit firing behavior during muscle fatigue have been reported and explained with varieties of conjectures. The disagreement amongst previous studies has resulted, in part, from the limited number of available motor units and from the misleading practice of grouping motor unit data across different subjects, contractions, and force levels. To establish a more clear understanding of motor unit control during fatigue, we investigated the firing behavior of motor units from the vastus lateralis muscle of individual subjects during a fatigue protocol of repeated voluntary constant force isometric contractions. Surface electromyographic decomposition technology provided the firings of 1,890 motor unit firing trains. These data revealed that to sustain the contraction force as the muscle fatigued, the following occurred: 1) motor unit firing rates increased; 2) new motor units were recruited; and 3) motor unit recruitment thresholds decreased. Although the degree of these adaptations was subject specific, the behavior was consistent in all subjects. When we compared our empirical observations with those obtained from simulation, we found that the fatigue-induced changes in motor unit firing behavior can be explained by increasing excitation to the motoneuron pool that compensates for the fatigue-induced decrease in muscle force twitch reported in empirical studies. Yet, the fundamental motor unit control scheme remains invariant throughout the development of fatigue. These findings indicate that the central nervous system regulates motor unit firing behavior by adjusting the operating point of the excitation to the motoneuron pool to sustain the contraction force as the muscle fatigues. Copyright © 2016 the American Physiological Society.

Hip Strength in Patients with Quadriceps Strength Deficits after ACL Reconstruction.

PubMed

Bell, David R; Trigsted, Stephanie M; Post, Eric G; Walden, Courtney E

2016-10-01

Quadriceps strength deficits persist for years after anterior cruciate ligament (ACL) reconstruction, and patients with these deficits often shift torque demands away from the knee extensors to the hip during functional tasks. However, it is not clear how quadriceps strength deficits may affect hip strength. Therefore, the purpose of this study was to investigate differences in lower extremity strength in individuals with ACL reconstruction with differing levels of quadriceps strength asymmetry. Isometric strength was recorded bilaterally in 135 participants (73 control and 62 with unilateral ACL reconstruction, time from surgery = 30.9 ± 17.6 months) from the knee extensors and flexors, hip extensors and abductors, and hip internal and external rotator muscle groups. Symmetry indices (limb symmetry index (LSI)) were created based on quadriceps strength, and subjects with ACL reconstruction were subdivided (high quadriceps (LSI ≥ 90%), n = 37; low quadriceps (LSI < 85%), n = 18). Individual group (control vs high quadriceps vs low quadriceps) by limb (reconstructed/nondominant vs healthy/dominant) repeated-measures ANOVA was used to compare strength (%BW) for each of the six joint motions of interest (knee extensors/flexors, hip abductors/extensors/external, and internal rotators) while controlling for time from surgery. An interaction was observed for quadriceps strength (P < 0.001), and the reconstructed limb in the low quadriceps group was weaker than all other limbs. A main effect for group was observed with the low quadriceps group having greater hip extension (P = 0.007) strength in both limbs compared with the other groups. Knee flexion strength was weaker in the reconstructed limb of the high quadriceps group (P = 0.047) compared with all other groups and limbs. Individuals with ACL reconstruction and involved limb quadriceps weakness have greater hip extension strength in both limbs compared with patients with bilateral strength symmetry and controls.

Nandrolone decanoate and physical activity affect quadriceps in peripubertal rats.

PubMed

Sretenovic, Jasmina; Ajdzanovic, Vladimir; Zivkovic, Vladimir; Srejovic, Ivan; Corbic, Milena; Milosevic, Verica; Jakovljevic, Vladimir; Milosavljevic, Zoran

2018-07-01

Anabolic androgenic steroids (AASs) are synthetic analogs of testosterone often used by athletes to increase the skeletal muscle mass. Our goal was to examine the effects of physical activity and physical activity combined with supraphysiological doses of nandrolone on functional morphology of the quadriceps muscle. The study included 32 peripubertal Wistar rats, divided into 4 groups: control (T-N-), nandrolone (T-N+), physical activity (T+N-) and physical activity plus nandrolone (T+N+) groups. The T+N- and T+N+ group swam for 4 weeks, 1 h/day, 5 days/week. The T-N+ and T+N+ groups received nandolone decanoate (20 mg/kg b.w.) once per week, subcutaneously. Subsequently, the rats were sacrificed and muscle specimens were prepared for the processing. Tissue sections were histochemically and immunohistochemically stained, while the image analysis was used for quantification. Longitudinal diameter of quadriceps muscle cells was increased for 21% in T-N+, for 57% in T+N- and for 64% in T+N+ group while cross section muscle cell area was increased in T-N+ for 19%, in T+N- for 47% and in T+N+ group for 59%, compared to the control. Collagen fibers covered area was increased in T-N+ group for 36%, in T+N- for 109% and in T+N+ group for 159%, compared to the control. Erythrocyte depots were decreased in T-N+ group and increased in T+N- and T+N+ group, in comparison with T-N-. VEGF depots were increased in all treated groups. Chronic administration of supraphysiological doses of AASs alone or in combination with physical activity induces hypertrophy and significant changes in the quadriceps muscle tissue structure. Copyright © 2018 Elsevier GmbH. All rights reserved.

Association of Muscle Endurance, Fatigability, and Strength With Functional Limitation and Mortality in the Health Aging and Body Composition Study

PubMed Central

Patel, Kushang V.; Fried, Linda F.; Robinson-Cohen, Cassianne; de Boer, Ian H.; Harris, Tamara; Murphy, Rachel A.; Satterfield, Suzanne; Goodpaster, Bret H.; Shlipak, Michael; Newman, Anne B.; Kestenbaum, Bryan

2017-01-01

Background: Mobility limitation is highly prevalent among older adults and is central to the loss of functional independence. Dynamic isokinetic muscle fatigue testing may reveal increased vulnerability to disability and mortality beyond strength testing. Methods: We studied community-dwelling older adults enrolled in the Health Aging and Body Composition study (age range: 71–82) free of mobility disability and who underwent isokinetic muscle fatigue testing in 1999–2000 (n = 1,963). Isokinetic quadriceps work and fatigue index was determined over 30 repetitions and compared with isometric quadriceps maximum torque. Work was normalized to leg lean mass accounting for gender-specific differences (specific work). The primary outcome was incident persistent severe lower extremity limitation (PSLL), defined as two consecutive reports of either having a lot of difficulty or being unable to walk 1/4 mile or climb 10 steps without resting. The secondary outcome was all-cause mortality. Results: There were 608 (31%) occurrences of incident PSLL and 488 (25%) deaths during median follow-up of 9.3 years. After adjustment, lower isokinetic work was associated with significantly greater risks of PSLL and mortality across the full measured range. Hazard ratios per standard deviation lower specific isokinetic work were 1.22 (95% CI 1.12, 1.33) for PSLL and 1.21 (95% CI 1.13, 1.30) for mortality, respectively. Lower isometric strength was associated with PSLL, but not mortality. Fatigue index was not associated with PSLL or mortality. Conclusions: Muscle endurance, estimated by isokinetic work, is an indicator of muscle health associated with mobility limitation and mortality providing important insight beyond strength testing. PMID:27907890

Intercostal and forearm muscle deoxygenation during respiratory fatigue in patients with heart failure: potential role of a respiratory muscle metaboreflex.

PubMed

Moreno, A M; Castro, R R T; Silva, B M; Villacorta, H; Sant'Anna Junior, M; Nóbrega, A C L

2014-11-01

The purpose of this study was to determine the effect of respiratory muscle fatigue on intercostal and forearm muscle perfusion and oxygenation in patients with heart failure. Five clinically stable heart failure patients with respiratory muscle weakness (age, 66 ± 12 years; left ventricle ejection fraction, 34 ± 3%) and nine matched healthy controls underwent a respiratory muscle fatigue protocol, breathing against a fixed resistance at 60% of their maximal inspiratory pressure for as long as they could sustain the predetermined inspiratory pressure. Intercostal and forearm muscle blood volume and oxygenation were continuously monitored by near-infrared spectroscopy with transducers placed on the seventh left intercostal space and the left forearm. Data were compared by two-way ANOVA and Bonferroni correction. Respiratory fatigue occurred at 5.1 ± 1.3 min in heart failure patients and at 9.3 ± 1.4 min in controls (P<0.05), but perceived effort, changes in heart rate, and in systolic blood pressure were similar between groups (P>0.05). Respiratory fatigue in heart failure reduced intercostal and forearm muscle blood volume (P<0.05) along with decreased tissue oxygenation both in intercostal (heart failure, -2.6 ± 1.6%; controls, +1.6 ± 0.5%; P<0.05) and in forearm muscles (heart failure, -4.5 ± 0.5%; controls, +0.5 ± 0.8%; P<0.05). These results suggest that respiratory fatigue in patients with heart failure causes an oxygen demand/delivery mismatch in respiratory muscles, probably leading to a reflex reduction in peripheral limb muscle perfusion, featuring a respiratory metaboreflex.

Methods for the assessment of peripheral muscle fatigue and its energy and metabolic determinants in COPD.

PubMed

Rondelli, Rafaella Rezende; Dal Corso, Simone; Simões, Alexandre; Malaguti, Carla

2009-11-01

It has been well established that, in addition to the pulmonary involvement, COPD has systemic consequences that can lead to peripheral muscle dysfunction, with greater muscle fatigue, lower exercise tolerance and lower survival in these patients. In view of the negative repercussions of early muscle fatigue in COPD, the objective of this review was to discuss the principal findings in the literature on the metabolic and bioenergy determinants of muscle fatigue, its functional repercussions, as well as the methods for its identification and quantification. The anatomical and functional substrate of higher muscle fatigue in COPD appears to include lower levels of high-energy phosphates, lower mitochondrial density, early lactacidemia, higher serum ammonia and reduced muscle perfusion. These alterations can be revealed by contraction failure, decreased firing rates of motor units and increased recruitment of motor units in a given activity, which can be functionally detected by a reduction in muscle strength, power and endurance. This review article also shows that various types of muscle contraction regimens and protocols have been used in order to detect muscle fatigue in this population. With this understanding, rehabilitation strategies can be developed in order to improve the resistance to muscle fatigue in this population.

Cardiorespiratory and neuromuscular deconditioning in fatigued and non-fatigued breast cancer survivors.

PubMed

Neil, Sarah E; Klika, Riggs J; Garland, S Jayne; McKenzie, Donald C; Campbell, Kristin L

2013-03-01

Fatigue is one of the most commonly reported side effects during treatment for breast cancer and can persist following treatment completion. Cancer-related fatigue after treatment is multifactorial in nature, and one hypothesized mechanism is cardiorespiratory and neuromuscular deconditioning. The purpose of this study was to compare cardiorespiratory and neuromuscular function in breast cancer survivors who had completed treatment and met the specified criteria for cancer-related fatigue and a control group of breast cancer survivors without fatigue. Participants in the fatigue (n = 16) and control group (n = 11) performed a maximal exercise test on a cycle ergometer for determination of peak power, power at lactate threshold, and VO(2) peak. Neuromuscular fatigue was induced with a sustained submaximal contraction of the right quadriceps. Central fatigue (failure of voluntary activation) was evaluated using twitch interpolation, and peripheral fatigue was measured with an electrically evoked twitch. Power at lactate threshold was lower in the fatigue group (p = 0.05). There were no differences between groups for power at lactate threshold as percentage of peak power (p = 0.10) or absolute or relative VO(2) peak (p = 0.08 and 0.33, respectively). When adjusted for age, the fatigue group had a lower power at lactate threshold (p = 0.02) and absolute VO(2) peak (p = 0.03). There were no differences between groups in change in any neuromuscular parameters after the muscle-fatiguing protocol. Findings support the hypothesis that cardiorespiratory deconditioning may play a role in the development and persistence of cancer-related fatigue following treatment. Future research into the use of exercise training to reduce cardiorespiratory deconditioning as a treatment for cancer-related fatigue is warranted to confirm these preliminary findings.

Effects of Physical Activity and Inactivity on Muscle Fatigue

PubMed Central

Bogdanis, Gregory C.

2012-01-01

The aim of this review was to examine the mechanisms by which physical activity and inactivity modify muscle fatigue. It is well known that acute or chronic increases in physical activity result in structural, metabolic, hormonal, neural, and molecular adaptations that increase the level of force or power that can be sustained by a muscle. These adaptations depend on the type, intensity, and volume of the exercise stimulus, but recent studies have highlighted the role of high intensity, short-duration exercise as a time-efficient method to achieve both anaerobic and aerobic/endurance type adaptations. The factors that determine the fatigue profile of a muscle during intense exercise include muscle fiber composition, neuromuscular characteristics, high energy metabolite stores, buffering capacity, ionic regulation, capillarization, and mitochondrial density. Muscle fiber-type transformation during exercise training is usually toward the intermediate type IIA at the expense of both type I and IIx myosin heavy-chain isoforms. High-intensity training results in increases of both glycolytic and oxidative enzymes, muscle capillarization, improved phosphocreatine resynthesis and regulation of K+, H+, and lactate ions. Decreases of the habitual activity level due to injury or sedentary lifestyle result in partial or even compete reversal of the adaptations due to previous training, manifested by reductions in fiber cross-sectional area, decreased oxidative capacity, and capillarization. Complete immobilization due to injury results in markedly decreased force output and fatigue resistance. Muscle unloading reduces electromyographic activity and causes muscle atrophy and significant decreases in capillarization and oxidative enzymes activity. The last part of the review discusses the beneficial effects of intermittent high-intensity exercise training in patients with different health conditions to demonstrate the powerful effect of exercise on health and well being. PMID

Skeletal muscle power and fatigue at the tolerable limit of ramp-incremental exercise in COPD.

PubMed

Cannon, Daniel T; Coelho, Ana Claudia; Cao, Robert; Cheng, Andrew; Porszasz, Janos; Casaburi, Richard; Rossiter, Harry B

2016-12-01

Muscle fatigue (a reduced power for a given activation) is common following exercise in chronic obstructive pulmonary disease (COPD). Whether muscle fatigue, and reduced maximal voluntary locomotor power, are sufficient to limit whole body exercise in COPD is unknown. We hypothesized in COPD: 1) exercise is terminated with a locomotor muscle power reserve; 2) reduction in maximal locomotor power is related to ventilatory limitation; and 3) muscle fatigue at intolerance is less than age-matched controls. We used a rapid switch from hyperbolic to isokinetic cycling to measure the decline in peak isokinetic power at the limit of incremental exercise ("performance fatigue") in 13 COPD patients (FEV 1 49 ± 17%pred) and 12 controls. By establishing the baseline relationship between muscle activity and isokinetic power, we apportioned performance fatigue into the reduction in muscle activation and muscle fatigue. Peak isokinetic power at intolerance was ~130% of peak incremental power in controls (274 ± 73 vs. 212 ± 84 W, P < 0.05), but ~260% in COPD patients (187 ± 141 vs. 72 ± 34 W, P < 0.05), greater than controls (P < 0.05). Muscle fatigue as a fraction of baseline peak isokinetic power was not different in COPD patients vs. controls (0.11 ± 0.20 vs. 0.19 ± 0.11). Baseline to intolerance, the median frequency of maximal isokinetic muscle activity, was unchanged in COPD patients but reduced in controls (+4.3 ± 11.6 vs. -5.5 ± 7.6%, P < 0.05). Performance fatigue as a fraction of peak incremental power was greater in COPD vs. controls and related to resting (FEV 1 /FVC) and peak exercise (V̇ E /maximal voluntary ventilation) pulmonary function (r 2 = 0.47 and 0.55, P < 0.05). COPD patients are more fatigable than controls, but this fatigue is insufficient to constrain locomotor power and define exercise intolerance. Copyright © 2016 the American Physiological Society.

Cancer cachexia decreases specific force and accelerates fatigue in limb muscle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roberts, B.M.; Frye, G.S.; Ahn, B.

Highlights: •C-26 cancer cachexia causes a significant decrease in limb muscle absolute force. •C-26 cancer cachexia causes a significant decrease in limb muscle specific force. •C-26 cancer cachexia decreases fatigue resistance in the soleus muscle. •C-26 cancer cachexia prolongs time to peak twitch tension in limb muscle. •C-26 cancer cachexia prolongs one half twitch relaxation time in limb muscle. -- Abstract: Cancer cachexia is a complex metabolic syndrome that is characterized by the loss of skeletal muscle mass and weakness, which compromises physical function, reduces quality of life, and ultimately can lead to mortality. Experimental models of cancer cachexia havemore » recapitulated this skeletal muscle atrophy and consequent decline in muscle force generating capacity. However, more recently, we provided evidence that during severe cancer cachexia muscle weakness in the diaphragm muscle cannot be entirely accounted for by the muscle atrophy. This indicates that muscle weakness is not just a consequence of muscle atrophy but that there is also significant contractile dysfunction. The current study aimed to determine whether contractile dysfunction is also present in limb muscles during severe Colon-26 (C26) carcinoma cachexia by studying the glycolytic extensor digitorum longus (EDL) muscle and the oxidative soleus muscle, which has an activity pattern that more closely resembles the diaphragm. Severe C-26 cancer cachexia caused significant muscle fiber atrophy and a reduction in maximum absolute force in both the EDL and soleus muscles. However, normalization to muscle cross sectional area further demonstrated a 13% decrease in maximum isometric specific force in the EDL and an even greater decrease (17%) in maximum isometric specific force in the soleus. Time to peak tension and half relaxation time were also significantly slowed in both the EDL and the solei from C-26 mice compared to controls. Since, in addition to postural control, the

Analysis of three different equations for predicting quadriceps femoris muscle strength in patients with COPD *

PubMed Central

Nellessen, Aline Gonçalves; Donária, Leila; Hernandes, Nidia Aparecida; Pitta, Fabio

2015-01-01

Abstract Objective: To compare equations for predicting peak quadriceps femoris (QF) muscle force; to determine the agreement among the equations in identifying QF muscle weakness in COPD patients; and to assess the differences in characteristics among the groups of patients classified as having or not having QF muscle weakness by each equation. Methods: Fifty-six COPD patients underwent assessment of peak QF muscle force by dynamometry (maximal voluntary isometric contraction of knee extension). Predicted values were calculated with three equations: an age-height-weight-gender equation (Eq-AHWG); an age-weight-gender equation (Eq-AWG); and an age-fat-free mass-gender equation (Eq-AFFMG). Results: Comparison of the percentage of predicted values obtained with the three equations showed that the Eq-AHWG gave higher values than did the Eq-AWG and Eq-AFFMG, with no difference between the last two. The Eq-AHWG showed moderate agreement with the Eq-AWG and Eq-AFFMG, whereas the last two also showed moderate, albeit lower, agreement with each other. In the sample as a whole, QF muscle weakness (< 80% of predicted) was identified by the Eq-AHWG, Eq-AWG, and Eq-AFFMG in 59%, 68%, and 70% of the patients, respectively (p > 0.05). Age, fat-free mass, and body mass index are characteristics that differentiate between patients with and without QF muscle weakness. Conclusions: The three equations were statistically equivalent in classifying COPD patients as having or not having QF muscle weakness. However, the Eq-AHWG gave higher peak force values than did the Eq-AWG and the Eq-AFFMG, as well as showing greater agreement with the other equations. PMID:26398750

Acute effects of static stretching on peak and end-range hamstring-to-quadriceps functional ratios.

PubMed

Sekir, Ufuk; Arabaci, Ramiz; Akova, Bedrettin

2015-10-18

To evaluate if static stretching influences peak and end-range functional hamstring-to-quadriceps (H/Q) strength ratios in elite women athletes. Eleven healthy female athletes in an elite competitive level participated to the study. All the participants fulfilled the static stretching or non-stretching (control) intervention protocol in a randomized design on different days. Two static unassisted stretching exercises, one in standing and one in sitting position, were used to stretch both the hamstring and quadriceps muscles during these protocols. The total time for the static stretching was 6 ± 1 min. The isokinetic peak torque measurements for the hamstring and quadriceps muscles in eccentric and concentric modes and the calculations for the functional H/Q strength ratios at angular velocities of 60°/s and 180°/s were made before (pre) and after (post) the control or stretching intervention. The strength measurements and functional strength ratio calculations were based during the entire- and end-range of knee extension. The pre-test scores for quadriceps and hamstring peak torque and end range values were not significantly different between the groups (P > 0.05). Subsequently, although the control group did not exhibit significant changes in quadriceps and hamstring muscle strength (P > 0.05), static stretching decreased eccentric and concentric quadriceps muscle strength at both the 60°/s and 180°/s test speeds (P < 0.01). Similarly, static stretching also decreased eccentric and concentric hamstring muscle strength at both the 60°/s and 180°/s test speeds (P < 0.01). On the other hand, when the functional H/Q strength ratios were taken into consideration, the pre-intervention values were not significant different between the groups both during the entire and end range of knee extension (P > 0.05). Furthermore, the functional H/Q strength ratios exhibited no significant alterations during the entire and end ranges of knee extension both in the static

Acute effects of static stretching on peak and end-range hamstring-to-quadriceps functional ratios

PubMed Central

Sekir, Ufuk; Arabaci, Ramiz; Akova, Bedrettin

2015-01-01

AIM: To evaluate if static stretching influences peak and end-range functional hamstring-to-quadriceps (H/Q) strength ratios in elite women athletes. METHODS: Eleven healthy female athletes in an elite competitive level participated to the study. All the participants fulfilled the static stretching or non-stretching (control) intervention protocol in a randomized design on different days. Two static unassisted stretching exercises, one in standing and one in sitting position, were used to stretch both the hamstring and quadriceps muscles during these protocols. The total time for the static stretching was 6 ± 1 min. The isokinetic peak torque measurements for the hamstring and quadriceps muscles in eccentric and concentric modes and the calculations for the functional H/Q strength ratios at angular velocities of 60°/s and 180°/s were made before (pre) and after (post) the control or stretching intervention. The strength measurements and functional strength ratio calculations were based during the entire- and end-range of knee extension. RESULTS: The pre-test scores for quadriceps and hamstring peak torque and end range values were not significantly different between the groups (P > 0.05). Subsequently, although the control group did not exhibit significant changes in quadriceps and hamstring muscle strength (P > 0.05), static stretching decreased eccentric and concentric quadriceps muscle strength at both the 60°/s and 180°/s test speeds (P < 0.01). Similarly, static stretching also decreased eccentric and concentric hamstring muscle strength at both the 60°/s and 180°/s test speeds (P < 0.01). On the other hand, when the functional H/Q strength ratios were taken into consideration, the pre-intervention values were not significant different between the groups both during the entire and end range of knee extension (P > 0.05). Furthermore, the functional H/Q strength ratios exhibited no significant alterations during the entire and end ranges of knee extension

The L-Z complexity of exercise-induced muscle fatigue based on acoustic myographye

NASA Astrophysics Data System (ADS)

Yijian, Min; Xinyuan, Liu; Tingting, Wang

2014-01-01

The mechanism of exercise fatigue was investigated during exercise using L-Z complexity of non-linear analysis. Muscle fatigue was induced in the sitting position by lifting the heel under a load. An acoustic myogram of the gastrocnemius was obtained until exhaustion. The different modes of the speed responses were calculated using the L-Z complexity method, which analyzes muscle fibers participation, while the exercise is in progress. The L-Z complexity decreased incrementally with decreases in muscle strength, reaching a minimum value when the muscle was exhausted. Our data indicate that the L-Z complexity method is easy to use and effective at revealing the dynamic characteristics and variations of exercise fatigue. This method could be used to monitor sports training.

Static stretching vs. dynamic warm-ups: a comparison of their effects on torque and electromyography output of the quadriceps and hamstring muscles.

PubMed

Williams, N; Coburn, J; Gillum, T

2015-11-01

The aim of this paper was to determine if two different warm-up protocols differently affect torque of the quadriceps and hamstrings, and electromyography (EMG) output of the rectus femoris (RF) and vastus lateralis (VL) when completing 30 maximal leg extensions and curls. Twenty-one healthy male (N.=8) and female (N.=13) subjects volunteered to participate in a familiarization session and three testing sessions. The three testing sessions control, dynamic, and static were completed in a counterbalanced order on non-consecutive days. First, subjects warmed-up on a treadmill for five minutes before completing six dynamic movements, six static-stretches, or no stretches. They then rested for five minutes before completing 30 maximal leg extensions and curls at a speed of 60 s-1. A significant decrease in quadriceps torque output over time was determined for the dynamic protocol when compared to the control (P<0.01) and static (P<0.05) protocols. A significant decrease was found in peak quadriceps torque for the dynamic protocol (P<0.01) when compared to the static, and a significant increase was found for the static protocol (P<0.05) when compared to the control. A significant decrease in average quadriceps torque was found for the dynamic protocol when compared to the static (P<0.05) and control (P<0.01) protocols. No difference was found in hamstring torque or EMG output of the RF and VL. Short duration static-stretching has the ability to increase peak and average torque of the leg extensors, while some types of anaerobic exercise involving maximal contractions to fatigue may be hindered by performing dynamic movements as part of the warm-up.

Multiple Causes of Fatigue during Shortening Contractions in Rat Slow Twitch Skeletal Muscle

PubMed Central

Hortemo, Kristin Halvorsen; Munkvik, Morten; Lunde, Per Kristian; Sejersted, Ole M.

2013-01-01

Fatigue in muscles that shorten might have other causes than fatigue during isometric contractions, since both cross-bridge cycling and energy demand are different in the two exercise modes. While isometric contractions are extensively studied, the causes of fatigue in shortening contractions are poorly mapped. Here, we investigate fatigue mechanisms during shortening contractions in slow twitch skeletal muscle in near physiological conditions. Fatigue was induced in rat soleus muscles with maintained blood supply by in situ shortening contractions at 37°C. Muscles were stimulated repeatedly (1 s on/off at 30 Hz) for 15 min against a constant load, allowing the muscle to shorten and perform work. Fatigue and subsequent recovery was examined at 20 s, 100 s and 15 min exercise. The effects of prior exercise were investigated in a second exercise bout. Fatigue developed in three distinct phases. During the first 20 s the regulatory protein Myosin Light Chain-2 (slow isoform, MLC-2s) was rapidly dephosphorylated in parallel with reduced rate of force development and reduced shortening. In the second phase there was degradation of high-energy phosphates and accumulation of lactate, and these changes were related to slowing of muscle relengthening and relaxation, culminating at 100 s exercise. Slowing of relaxation was also associated with increased leak of calcium from the SR. During the third phase of exercise there was restoration of high-energy phosphates and elimination of lactate, and the slowing of relaxation disappeared, whereas dephosphorylation of MLC-2s and reduced shortening prevailed. Prior exercise improved relaxation parameters in a subsequent exercise bout, and we propose that this effect is a result of less accumulation of lactate due to more rapid onset of oxidative metabolism. The correlation between dephosphorylation of MLC-2s and reduced shortening was confirmed in various experimental settings, and we suggest MLC-2s as an important regulator of

Shoulder girdle muscle activity and fatigue in traditional and improved design carpet weaving workstations.

PubMed

Allahyari, Teimour; Mortazavi, Narges; Khalkhali, Hamid Reza; Sanjari, Mohammad Ali

2016-01-01

Work-related musculoskeletal disorders in the neck and shoulder regions are common among carpet weavers. Working for prolonged hours in a static and awkward posture could result in an increased muscle activity and may lead to musculoskeletal disorders. Ergonomic workstation improvements can reduce muscle fatigue and the risk of musculoskeletal disorders. The aim of this study is to assess and to compare upper trapezius and middle deltoid muscle activity in 2 traditional and improved design carpet weaving workstations. These 2 workstations were simulated in a laboratory and 12 women carpet weavers worked for 3 h. Electromyography (EMG) signals were recorded during work in bilateral upper trapezius and bilateral middle deltoid. The root mean square (RMS) and median frequency (MF) values were calculated and used to assess muscle load and fatigue. Repeated measure ANOVA was performed to assess the effect of independent variables on muscular activity and fatigue. The participants were asked to report shoulder region fatigue on the Borg's Category-Ratio scale (Borg CR-10). Root mean square values in workstation A are significantly higher than in workstation B. Furthermore, EMG amplitude was higher in bilateral trapezius than in bilateral deltoid. However, muscle fatigue was not observed in any of the workstations. The results of the study revealed that muscle load in a traditional workstation was high, but fatigue was not observed. Further studies investigating other muscles involved in carpet weaving tasks are recommended. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

Spatial distribution of motor units recruited during electrical stimulation of the quadriceps muscle versus the femoral nerve.

PubMed

Rodriguez-Falces, Javier; Maffiuletti, Nicola A; Place, Nicolas

2013-11-01

In this study we investigated differences in the spatial recruitment of motor units (MUs) in the quadriceps when electrical stimulation is applied over the quadriceps belly versus the femoral nerve. M-waves and mechanical twitches were evoked using over-the-quadriceps and femoral nerve stimulation of gradually increasing intensity from 22 young, healthy subjects. Spatial recruitment was investigated using recruitment curves of M-waves recorded from the vastus medialis (VM) and vastus lateralis (VL) and of twitches recorded from the quadriceps. At maximal stimulation intensity (Imax), no differences were found between nerve and over-the-quadriceps stimulation. At submaximal intensities, VL M-wave amplitude was higher for over-the-quadriceps stimulation at 40% Imax, and peak twitch force was greater for nerve stimulation at 60% and 80% Imax. For the VM, MU spatial recruitment during nerve and over-the-quadriceps stimulation of increasing intensity occurred in a similar manner, whereas significant differences were observed for the VL. Copyright © 2013 Wiley Periodicals, Inc.

Effects of fatigue on lower limb, pelvis and trunk kinematics and muscle activation: Gender differences.

PubMed

Lessi, Giovanna Camparis; Dos Santos, Ana Flávia; Batista, Luis Fylipe; de Oliveira, Gabriela Clemente; Serrão, Fábio Viadanna

2017-02-01

Muscle fatigue is associated with biomechanical changes that may lead to anterior cruciate ligament (ACL) injuries. Alterations in trunk and pelvis kinematics may also be involved in ACL injury. Although some studies have compared the effects of muscle fatigue on lower limb kinematics between men and women, little is known about its effects on pelvis and trunk kinematics. The aim of the study was to compare the effects of fatigue on lower limb, pelvis and trunk kinematics and muscle activation between men and women during landing. The participants included forty healthy subjects. We performed kinematic analysis of the trunk, pelvis, hip and knee and muscle activation analysis of the gluteal muscles, vastus lateralis and biceps femoris, during a single-leg landing before and after fatigue. Men had greater trunk flexion than women after fatigue. After fatigue, a decrease in peak knee flexion and an increase in Gmax and BF activation were observed. The increase in the trunk flexion can decrease the anterior tibiofemoral shear force resulted from the lower knee flexion angle, thereby decreasing the stress on the ACL. Copyright © 2016 Elsevier Ltd. All rights reserved.

Muscle fatigue in frog semitendinosus: alterations in contractile function

NASA Technical Reports Server (NTRS)

Thompson, L. V.; Balog, E. M.; Riley, D. A.; Fitts, R. H.

1992-01-01

The purpose of this study was to characterize the contractile properties of the frog semitendinosus (ST) muscle before and during recovery from fatigue, to relate the observed functional changes to alterations in specific steps in the crossbridge model of muscle contraction, and to determine how fatigue affects the force-frequency relationship. The frog ST (22 degrees C) was fatigued by direct electrical stimulation with 100-ms 150-Hz trains at 1/s for 5 min. The fatigue protocol reduced peak twitch (Pt) and tetanic (Po) force to 32 and 8.5% of initial force, respectively. The decline in Pt was less than Po, in part due to a prolongation in the isometric contraction time (CT), which increased to 300% of the initial value. The isometric twitch duration was greatly prolonged as reflected by the lengthened CT and the 800% increase in the one-half relaxation time (1/2RT). Both Pt and Po showed a biphasic recovery, a rapid initial phase (2 min) followed by a slower (40 min) return to the prefatigue force. CT and 1/2RT also recovered in two phases, returning to 160 and 265% of control in the first 5 min. CT returned to the prefatigue value between 35 and 40 min, whereas even at 60 min 1/2RT was 133% of control. The maximal velocity of shortening, determined by the slack test, was significantly reduced [from 6.7 +/- 0.5 to 2.5 +/- 0.4 optimal muscle length/s] at fatigue. The force-frequency relationship was shifted to the left, so that optimal frequency for generating Po was reduced.(ABSTRACT TRUNCATED AT 250 WORDS).

Muscle activity, time to fatigue, and maximum task duration at different levels of production standard time

PubMed Central

Nur, Nurhayati Mohd; Dawal, Siti Zawiah Md; Dahari, Mahidzal; Sanusi, Junedah

2015-01-01

[Purpose] This study investigated the variations in muscle fatigue, time to fatigue, and maximum task duration at different levels of production standard time. [Methods] Twenty subjects performed repetitive tasks at three different levels of production standard time corresponding to “normal”, “hard” and “very hard”. Surface electromyography was used to measure the muscle activity. [Results] The results showed that muscle activity was significantly affected by the production standard time level. Muscle activity increased twice in percentage as the production standard time shifted from hard to very hard (6.9% vs. 12.9%). The muscle activity increased over time, indicating muscle fatigue. The muscle fatigue rate increased for the harder production standard time (Hard: 0.105; Very hard: 0.115), which indicated the associated higher risk of work-related musculoskeletal disorders. Muscle fatigue was also found to occur earlier for hard and very hard production standard times. [Conclusion] It is recommended that the maximum task duration should not exceed 5.6, 2.9, and 2.2 hours for normal, hard, and very hard production standard times, respectively, in order to maintain work performance and minimize the risk of work-related musculoskeletal disorders. PMID:26311974

MUSCLE WEAKNESS, FATIGUE, AND TORQUE VARIABILITY: EFFECTS OF AGE AND MOBILITY STATUS

PubMed Central

KENT-BRAUN, JANE A.; CALLAHAN, DAMIEN M.; FAY, JESSICA L.; FOULIS, STEPHEN A.; BUONACCORSI, JOHN P.

2013-01-01

Introduction Whereas deficits in muscle function, particularly power production, develop in old age and are risk factors for mobility impairment, a complete understanding of muscle fatigue during dynamic contractions is lacking. We tested hypotheses related to torque-producing capacity, fatigue resistance, and variability of torque production during repeated maximal contractions in healthy older, mobility-impaired older, and young women. Methods Knee extensor fatigue (decline in torque) was measured during 4 min of dynamic contractions. Torque variability was characterized using a novel 4-component logistic regression model. Results Young women produced more torque at baseline and during the protocol than older women (P < 0.001). Although fatigue did not differ between groups (P = 0.53), torque variability differed by group (P = 0.022) and was greater in older impaired compared with young women (P = 0.010). Conclusions These results suggest that increased torque variability may combine with baseline muscle weakness to limit function, particularly in older adults with mobility impairments. PMID:23674266

Relationship of quadriceps muscle power and optimal shortening velocity with angiotensin-converting enzyme activity in older women.

PubMed

Kostka, Joanna; Sikora, Joanna; Kostka, Tomasz

2017-01-01

The goal of this study was to assess whether angiotensin-converting enzyme (ACE) activity is related to muscle function (strength, power and velocity), as well as to assess if ACE inhibitors (ACEIs) and other angiotensin system blocking medications (ASBMs) influence muscle performance in elderly women. Ninety-five community-dwelling elderly women took part in this study. Anthropometric data, blood ACE activity analysis, maximum power (P max ) and optimal shortening velocity (υ opt ) of the knee extensor muscles, handgrip strength, physical activity (PA) and functional performance were measured. Women taking ACEI were on average almost 2 years older than the women who did not take ACEI. They took more medicines and were also characterized by significantly lower level of ACE, but they did not differ in terms of PA level, results of functional performance and parameters characterizing muscle functions. No correlations of ACE activity with P max and handgrip strength, as well as with PA or functional performance were found. Higher ACE activity was connected with lower υ opt for women who did not take any ASBMs (rho =-0.37; p =0.01). Serum ACE activity was not associated with muscle strength, power and functional performance in both ASBM users and nonusers, but was associated with optimal shortening velocity of quadriceps muscles in older women. Further prospective studies are needed to assess if ACEIs or other ASBMs may slow down the decline in muscle function and performance.

Influence on muscle oxygenation to EMG parameters at different skeletal muscle contraction

NASA Astrophysics Data System (ADS)

Zhang, Li; Song, Gaoqing

2010-02-01

The purpose of this study is to investigate the influence of muscle oxygenation on EMG parameters during isometric and incremental exercises and to observe the relationship between EMG parameters and muscle oxygenation. Twelve rowers took part in the tests. Near infrared spectrometer was utilized for measurements of muscle oxygenation on lateral quadriceps. sEMG measurement is performed for EMG parameters during isometric and incremental exercises. Results indicated that Oxy-Hb decrease significantly correlated with IEMG, E/T ratio and frequency of impulse signal during 1/3 MVC and 2/3 MVC isometric exercise, and it is also correlated with IEMG, E/T ratio and frequency of impulse signal. Increase of IEMG occurred at the time after Oxy-Hb decrease during incremental exercise and highly correlated with BLa. It is concluded that no matter how heavy the intensity is, Oxy-Hb dissociation may play an important role in affecting EMG parameters of muscle fatigue during isometric exercise. 2) EMG parameters may be influenced by Oxy-Hb dissociation and blood lactate concentration during dynamic exercise.

Influence on muscle oxygenation to EMG parameters at different skeletal muscle contraction

NASA Astrophysics Data System (ADS)

Zhang, Li; Song, Gaoqing

2009-10-01

The purpose of this study is to investigate the influence of muscle oxygenation on EMG parameters during isometric and incremental exercises and to observe the relationship between EMG parameters and muscle oxygenation. Twelve rowers took part in the tests. Near infrared spectrometer was utilized for measurements of muscle oxygenation on lateral quadriceps. sEMG measurement is performed for EMG parameters during isometric and incremental exercises. Results indicated that Oxy-Hb decrease significantly correlated with IEMG, E/T ratio and frequency of impulse signal during 1/3 MVC and 2/3 MVC isometric exercise, and it is also correlated with IEMG, E/T ratio and frequency of impulse signal. Increase of IEMG occurred at the time after Oxy-Hb decrease during incremental exercise and highly correlated with BLa. It is concluded that no matter how heavy the intensity is, Oxy-Hb dissociation may play an important role in affecting EMG parameters of muscle fatigue during isometric exercise. 2) EMG parameters may be influenced by Oxy-Hb dissociation and blood lactate concentration during dynamic exercise.

The effects of load carriage and muscle fatigue on lower-extremity joint mechanics.

PubMed

Wang, He; Frame, Jeff; Ozimek, Elicia; Leib, Daniel; Dugan, Eric L

2013-09-01

Military personnel are commonly afflicted by lower-extremity overuse injuries. Load carriage and muscular fatigue are major stressors during military basic training. To examine effects of load carriage and muscular fatigue on lower-extremity joint mechanics during walking. Eighteen men performed the following tasks: unloaded walking, walking with a 32-kg load, fatigued walking with a 32-kg load, and fatigued walking. After the second walking task, muscle fatigue was elicited through a fatiguing protocol consisting of metered step-ups and heel raises with a 16-kg load. Each walking task was performed at 1.67 m x s(-1) for 5 min. Walking movement was tracked by a VICON motion capture system at 120 Hz. Ground reaction forces were collected by a tandem force instrumented treadmill (AMTI) at 2,400 Hz. Lower-extremity joint mechanics were calculated in Visual 3D. There was no interaction between load carriage and fatigue on lower-extremity joint mechanics (p > .05). Both load carriage and fatigue led to pronounced alterations of lower-extremity joint mechanics (p < .05). Load carriage resulted in increases of pelvis anterior tilt, hip and knee flexion at heel contact, and increases of hip, knee, and ankle joint moments and powers during weight acceptance. Muscle fatigue led to decreases of ankle dorsiflexion at heel contact, dorsiflexor moment, and joint power at weight acceptance. In addition, muscle fatigue increased demand for hip extensor moment and power at weight acceptance. Statistically significant changes in lower-extremity joint mechanics during loaded and fatigued walking may expose military personnel to increased risk for overuse injuries.

An analysis of the activity and muscle fatigue of the muscles around the neck under the three most frequent postures while using a smartphone

PubMed Central

Choi, Jung-Hyun; Jung, Min-Ho; Yoo, Kyung-Tae

2016-01-01

[Purpose] The purpose of this study was to identify changes in the activity and fatigue of the splenius capitis and upper trapezius muscles, which are agonists to the muscles supporting the head, under the three postures most frequently adopted while using a smartphone. [Subjects and Methods] The subjects were 15 college students in their 20s. They formed a single group and had to adopt three different postures (maximum bending, middle bending, and neutral). While the 15 subjects maintained the postures, muscle activity and fatigue were measured using surface electromyography. [Results] Comparison of the muscle fatigue caused by each posture showed statistically significant differences for the right splenius capitis, left splenius capitis, and left upper trapezius muscles. In addition, maintaining the maximum bending posture while using a smartphone resulted in higher levels of fatigue in the right splenius capitis, left splenius capitis, and left upper trapezius muscles compared with those for the middle bending posture. [Conclusion] Therefore, this study suggests that individuals should bend their neck slightly when using a smartphone, rather than bending it too much, or keep their neck straight to reduce fatigue of the cervical erector muscles. PMID:27313393

An analysis of the activity and muscle fatigue of the muscles around the neck under the three most frequent postures while using a smartphone.

PubMed

Choi, Jung-Hyun; Jung, Min-Ho; Yoo, Kyung-Tae

2016-05-01

[Purpose] The purpose of this study was to identify changes in the activity and fatigue of the splenius capitis and upper trapezius muscles, which are agonists to the muscles supporting the head, under the three postures most frequently adopted while using a smartphone. [Subjects and Methods] The subjects were 15 college students in their 20s. They formed a single group and had to adopt three different postures (maximum bending, middle bending, and neutral). While the 15 subjects maintained the postures, muscle activity and fatigue were measured using surface electromyography. [Results] Comparison of the muscle fatigue caused by each posture showed statistically significant differences for the right splenius capitis, left splenius capitis, and left upper trapezius muscles. In addition, maintaining the maximum bending posture while using a smartphone resulted in higher levels of fatigue in the right splenius capitis, left splenius capitis, and left upper trapezius muscles compared with those for the middle bending posture. [Conclusion] Therefore, this study suggests that individuals should bend their neck slightly when using a smartphone, rather than bending it too much, or keep their neck straight to reduce fatigue of the cervical erector muscles.

Electrically-induced muscle fatigue affects feedforward mechanisms of control.

PubMed

Monjo, F; Forestier, N

2015-08-01

To investigate the effects of focal muscle fatigue induced by electromyostimulation (EMS) on Anticipatory Postural Adjustments (APAs) during arm flexions performed at maximal velocity. Fifteen healthy subjects performed self-paced arm flexions at maximal velocity before and after the completion of fatiguing electromyostimulation programs involving the medial and anterior deltoids and aiming to degrade movement peak acceleration. APA timing and magnitude were measured using surface electromyography. Following muscle fatigue, despite a lower mechanical disturbance evidenced by significant decreased peak accelerations (-12%, p<.001), APAs remained unchanged as compared to control trials (p>.11 for all analyses). The fatigue signals evoked by externally-generated contractions seem to be gated by the Central Nervous System and result in postural strategy changes which aim to increase the postural safety margin. EMS is widely used in rehabilitation and training programs for its neuromuscular function-related benefits. However and from a motor control viewpoint, the present results show that the use of EMS can lead to acute inaccuracies in predictive motor control. We propose that clinicians should investigate the chronic and global effects of EMS on motor control. Copyright © 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Nicorandil improves post-fatigue tension in slow skeletal muscle fibers by modulating glutathione redox state.

PubMed

Sánchez-Duarte, E; Trujillo, X; Cortés-Rojo, C; Saavedra-Molina, A; Camargo, G; Hernández, L; Huerta, M; Montoya-Pérez, R

2017-04-01

Fatigue is a phenomenon in which force reduction has been linked to impairment of several biochemical processes. In skeletal muscle, the ATP-sensitive potassium channels (K ATP ) are actively involved in myoprotection against metabolic stress. They are present in sarcolemma and mitochondria (mitoK ATP channels). K + channel openers like nicorandil has been recognized for their ability to protect skeletal muscle from ischemia-reperfusion injury, however, the effects of nicorandil on fatigue in slow skeletal muscle fibers has not been explored, being the aim of this study. Nicorandil (10 μM), improved the muscle function reversing fatigue as increased post-fatigue tension in the peak and total tension significantly with respect to the fatigued condition. However, this beneficial effect was prevented by the mitoK ATP channel blocker 5-hydroxydecanoate (5-HD, 500 μM) and by the free radical scavenger N-2-mercaptopropionyl glycine (MPG, 1 mM), but not by the nitric oxide (NO) synthase inhibitor Nω-nitro-L-arginine methyl ester (L-NAME, 100 μM). Nicorandil also decreased lipid peroxidation and maintained both reduced glutathione (GSH) levels and an elevated GSH/GSSG ratio, whereas total glutathione (TGSH) remained unaltered during post-fatigue tension. In addition, NO production, measured through nitrite concentrations was significantly increased with nicorandil during post-fatigue tension; this increase remained unaltered in the presence of nicorandil plus L-NAME, nonetheless, this effect was reversed with nicorandil plus MPG. Hence, these results suggest that nicorandil improves the muscle function reversing fatigue in slow skeletal muscle fibers of chicken through its effects not only as a mitoK ATP channel opener but also as NO donor and as an antioxidant.

Functional characterization of muscle fibres from patients with chronic fatigue syndrome: case-control study.

PubMed

Pietrangelo, T; Toniolo, L; Paoli, A; Fulle, S; Puglielli, C; Fanò, G; Reggiani, C

2009-01-01

Chronic fatigue syndrome (CFS) is a disabling condition characterized by unexplained chronic fatigue that impairs normal activities. Although immunological and psychological aspects are present, symptoms related to skeletal muscles, such as muscle soreness, fatigability and increased lactate accumulation, are prominent in CFS patients. In this case-control study, the phenotype of the same biopsy samples was analyzed by determining i) fibre-type proportion using myosin isoforms as fibre type molecular marker and gel electrophoresis as a tool to separate and quantify myosin isoforms, and ii) contractile properties of manually dissected, chemically made permeable and calcium-activated single muscle fibres. The results showed that fibre-type proportion was significantly altered in CSF samples, which showed a shift from the slow- to the fast-twitch phenotype. Cross sectional area, force, maximum shortening velocity and calcium sensitivity were not significantly changed in single muscle fibres from CSF samples. Thus, the contractile properties of muscle fibres were preserved but their proportion was changed, with an increase in the more fatigue-prone, energetically expensive fast fibre type. Taken together, these results support the view that muscle tissue is directly involved in the pathogenesis of CSF and it might contribute to the early onset of fatigue typical of the skeletal muscles of CFS patients.

Local Muscle Fatigue and 3D Kinematics of the Cervical Spine in Healthy Subjects.

PubMed

Niederer, Daniel; Vogt, Lutz; Pippig, Torsten; Wall, Rudolf; Banzer, Winfried

2016-01-01

The authors aimed to further explore the effects of local muscle fatigue on cervical 3D kinematics and the interrelationship between these kinematic characteristics and local muscle endurance capacity in the unimpaired cervical spine. Twenty healthy subjects (38 ± 10 years; 5 women) performed 2 × 10 maximal cervical flexion-extension movements. Isometric muscle endurance tests (prone/supine lying) were applied between sets to induce local muscle fatigue quantified by Borg scale rates of perceived exertion (RPE) and slope in mean power frequency (MPF; surface electromyography; m. sternocleidomastoideus, m. splenius capitis). Cervical motion characteristics (maximal range of motion [ROM], coefficient of variation of the 10 repetitive movements, mean angular velocity, conjunct movements in transversal and frontal plane) were calculated from raw 3D ultrasonic movement data. Average isometric strength testing duration for flexion and extension correlated to the cervical ROM (r = .49/r = .48; p < .05). However, Student's t test demonstrated no significant alterations in any kinematic parameter following local muscle fatigue (p > .05). Although subjects' cervical muscle endurance capacity and motor output seems to be conjugated, no impact of local cervical muscle fatigue on motor function was shown. These findings underline the importance of complementary measures to address muscular performance and kinematic characteristics in outcome assessment and functional rehabilitation of the cervical spine.

Shoulder External Rotation Fatigue and Scapular Muscle Activation and Kinematics in Overhead Athletes

PubMed Central

Joshi, Mithun; Thigpen, Charles A.; Bunn, Kevin; Karas, Spero G.; Padua, Darin A.

2011-01-01

Context: Glenohumeral external rotation (GH ER) muscle fatigue might contribute to shoulder injuries in overhead athletes. Few researchers have examined the effect of such fatigue on scapular kinematics and muscle activation during a functional movement pattern. Objective: To examine the effects of GH ER muscle fatigue on upper trapezius, lower trapezius, serratus anterior, and infraspinatus muscle activation and to examine scapular kinematics during a diagonal movement task in overhead athletes. Setting: Human performance research laboratory. Design: Descriptive laboratory study. Patients or Other Participants: Our study included 25 overhead athletes (15 men, 10 women; age = 20 ± 2 years, height = 180 ± 11 cm, mass = 80 ± 11 kg) without a history of shoulder pain on the dominant side. Interventions: We tested the healthy, dominant shoulder through a diagonal movement task before and after a fatiguing exercise involving low-resistance, high-repetition, prone GH ER from 0° to 75° with the shoulder in 90° of abduction. Main Outcome Measure(s): Surface electromyography was used to measure muscle activity for the upper trapezius, lower trapezius, serratus anterior, and infraspinatus. An electromyographic motion analysis system was used to assess 3-dimensional scapular kinematics. Repeated-measures analyses of variance (phase × condition) were used to test for differences. Results: We found a decrease in ascending-phase and descending-phase lower trapezius activity (F1,25 = 5.098, P = .03) and an increase in descending-phase infraspinatus activity (F1,25 = 5.534, P = .03) after the fatigue protocol. We also found an increase in scapular upward rotation (F1,24 = 3.7, P = .04) postfatigue. Conclusions: The GH ER muscle fatigue protocol used in this study caused decreased lower trapezius and increased infraspinatus activation concurrent with increased scapular upward rotation range of motion during the functional task. This highlights the interdependence of scapular

Fatigue mechanisms in patients with cancer: effects of tumor necrosis factor and exercise on skeletal muscle

NASA Technical Reports Server (NTRS)

St Pierre, B. A.; Kasper, C. E.; Lindsey, A. M.

1992-01-01

Fatigue is a common adverse effect of cancer and its therapy. However, the specific mechanisms underlying cancer fatigue are unclear. One physiologic mechanism may involve changes in skeletal muscle protein stores or metabolite concentration. A reduction in skeletal muscle protein stores may result from endogenous tumor necrosis factor (TNF) or from TNF administered as antineoplastic therapy. This muscle wasting would require patients to exert an unusually high amount of effort to generate adequate contractile force during exercise performance or during extended periods of sitting or standing. This additional effort could result in the onset of fatigue. Additionally, cancer fatigue may develop or become exacerbated during exercise as a consequence of changes in the concentration of skeletal muscle metabolites. These biochemical alterations may interfere with force that is produced by the muscle contractile proteins. These physiologic changes may play a role in the decision to include exercise in the rehabilitation plans of patients with cancer. They also may affect ideas about fatigue.

Electromyographic fatigue of orbicular oris muscles during exercises in mouth and nasal breathing children.

PubMed

Busanello-Stella, Angela Ruviaro; Blanco-Dutra, Ana Paula; Corrêa, Eliane Castilhos Rodrigues; Silva, Ana Maria Toniolo da

2015-01-01

To investigate the process of fatigue in orbicularis oris muscles by analyzing the median frequency of electromyographic signal and the referred fatigue time, according to the breathing mode and the facial pattern. The participants were 70 children, aged 6 to 12 years, who matched the established criteria. To be classified as 36 nasal-breathing and 34 mouth-breathing children, they underwent speech-language, otorhinolaryngologic, and cephalometric evaluation. For the electromyographic assessment, the children had to sustain lip dumbbells weighing 40, 60, and 100 g and a lip exerciser, until the feeling of fatigue. Median frequency was analyzed in 5, 10, 15, and 20 seconds of activity. The referred time of the feeling of fatigue was also recorded. Data were analyzed through the analysis of variance--repeated measures (post hoc Tukey's test), Kruskal-Wallis test, and Mann-Whitney U-test. A significant decrease in the median frequency from 5 seconds of activity was observed, independently from the comparison between the groups. On comparison, the muscles did not show significant decrease. The reported time for the feeling of fatigue was shorter for mouth-breathing individuals. This feeling occurred after the significant decrease in the median frequency. There were signals that indicated myoelectric fatigue for the orbicularis oris muscles, in both groups analyzed, from the first 5 seconds of activity. Myoelectric fatigue in the orbicularis oris muscles preceded the reported feeling of fatigue in all groups. The account for fatigue time was influenced by only the breathing pattern, occurring more precociously in mouth-breathing children.

On simulating sustained isometric muscle fatigue: a phenomenological model considering different fiber metabolisms.

PubMed

Grasa, J; Sierra, M; Muñoz, M J; Soteras, F; Osta, R; Calvo, B; Miana-Mena, F J

2014-11-01

The present study shows a new computational FEM technique to simulate the evolution of the mechanical response of 3D muscle models subjected to fatigue. In an attempt to obtain very realistic models, parameters needed to adjust the mathematical formulation were obtained from in vivo experimental tests. The fatigue contractile properties of three different rat muscles (Tibialis Anterior, Extensor Digitorium Longus and Soleus) subjected to sustained maximal isometric contraction were determined. Experiments were conducted on three groups [Formula: see text] of male Wistar rats [Formula: see text] using a protocol previously developed by the authors for short tetanic contractions. The muscles were subjected to an electrical stimulus to achieve tetanic contraction during 10 s. The parameters obtained for each muscle were incorporated into a finite strain formulation for simulating active and passive behavior of muscles with different fiber metabolisms. The results show the potential of the model to predict muscle fatigue under high-frequency stimulation and the 3D distribution of mechanical variables such as stresses and strains.

Extended healing validation of an artificial tendon to connect the quadriceps muscle to the Tibia: 180-day study.

PubMed

Melvin, Alan J; Litsky, Alan S; Mayerson, Joel L; Stringer, Keith; Juncosa-Melvin, Natalia

2012-07-01

Whenever a tendon or its bone insertion is disrupted or removed, existing surgical techniques provide a temporary connection or scaffolding to promote healing, but the interface of living to non-living materials soon breaks down under the stress of these applications, if it must bear the load more than acutely. Patients are thus disabled whose prostheses, defect size, or mere anatomy limit the availability or outcomes of such treatments. Our group developed the OrthoCoupler™ device to join skeletal muscle to prosthetic or natural structures without this interface breakdown. In this study, the goat knee extensor mechanism (quadriceps tendon, patella, and patellar tendon) was removed from the right hind limb in 16 goats. The device connected the quadriceps muscle to a stainless steel bone plate on the tibia. Mechanical testing and histology specimens were collected from each operated leg and contralateral unoperated control legs at 180 days. Maximum forces in the operated leg (vs. unoperated) were 1,400 ± 93 N (vs. 1,179 ± 61 N), linear stiffnesses were 33 ± 3 N/mm (vs. 37 ± 4 N/mm), and elongations at failure were 92.1 ± 5.3 mm (vs. 68.4 ± 3.8 mm; mean ± SEM). Higher maximum forces (p = 0.02) and elongations at failure (p=0.008) of legs with the device versus unoperated controls were significant; linear stiffnesses were not (p=0.3). We believe this technology will yield improved procedures for clinical challenges in orthopedic oncology, revision arthroplasty, tendon transfer, and tendon injury reconstruction. Copyright © 2011 Orthopaedic Research Society.

Fatigue-Induced Changes in Movement Pattern and Muscle Activity During Ballet Releve on Demi-Pointe.

PubMed

Lin, Cheng-Feng; Lee, Wan-Chin; Chen, Yi-An; Hsue, Bih-Jen

2016-08-01

Fatigue in ballet dancers may lead to injury, particularly in the lower extremities. However, few studies have investigated the effects of fatigue on ballet dancers' performance and movement patterns. Thus, the current study examines the effect of fatigue on the balance, movement pattern, and muscle activities of the lower extremities in ballet dancers. Twenty healthy, female ballet dancers performed releve on demi-pointe before and after fatigue. The trajectory of the whole body movement and the muscle activities of the major lower extremity muscles were recorded continuously during task performance. The results show that fatigue increases the medial-lateral center of mass (COM) displacement and hip and trunk motion, but decreases the COM velocity and ankle motion. Moreover, fatigue reduces the activities of the hamstrings and tibialis anterior, but increases that of the soleus. Finally, greater proximal hip and trunk motions are applied to compensate for the effects of fatigue, leading to a greater COM movement. Overall, the present findings show that fatigue results in impaired movement control and may therefore increase the risk of dance injury.

Dysregulation of metabolic-associated pathways in muscle of breast cancer patients: preclinical evaluation of interleukin-15 targeting fatigue.

PubMed

Bohlen, Joseph; McLaughlin, Sarah L; Hazard-Jenkins, Hannah; Infante, Aniello M; Montgomery, Cortney; Davis, Mary; Pistilli, Emidio E

2018-03-26

Breast cancer patients report a perception of increased muscle fatigue, which can persist following surgery and standardized therapies. In a clinical experiment, we tested the hypothesis that pathways regulating skeletal muscle fatigue are down-regulated in skeletal muscle of breast cancer patients and that different muscle gene expression patterns exist between breast tumour subtypes. In a preclinical study, we tested the hypothesis that mammary tumour growth in mice induces skeletal muscle fatigue and that overexpression of the cytokine interleukin-15 (IL-15) can attenuate mammary tumour-induced muscle fatigue. Early stage non-metastatic female breast cancer patients (n = 14) and female non-cancer patients (n = 6) provided a muscle biopsy of the pectoralis major muscle during mastectomy, lumpectomy, or breast reconstruction surgeries. The breast cancer patients were diagnosed with either luminal (ER + /PR + , n = 6), triple positive (ER + /PR + /Her2/neu + , n = 5), or triple negative (ER - /PR - /Her2/neu - , n = 3) breast tumours and were being treated with curative intent either with neoadjuvant chemotherapy followed by surgery or surgery followed by standard post-operative therapy. Biopsies were used for RNA-sequencing to compare the skeletal muscle gene expression patterns between breast cancer patients and non-cancer patients. The C57BL/6 mouse syngeneic mammary tumour cell line, E0771, was used to induce mammary tumours in immunocompetent mice, and isometric muscle contractile properties and fatigue properties were analysed following 4 weeks of tumour growth. RNA-sequencing and subsequent bioinformatics analyses revealed a dysregulation of canonical pathways involved in oxidative phosphorylation, mitochondrial dysfunction, peroxisome proliferator-activated receptor signalling and activation, and IL-15 signalling and production. In a preclinical mouse model of breast cancer, the rate of muscle fatigue was greater in mice exposed to mammary tumour

Growth trend of the quadriceps femoris muscle in junior Olympic weight lifters: an 18-month follow-up survey.

PubMed

Kanehisa, Hiroaki; Funato, Kazuo; Kuno, Shinya; Fukunaga, Tetsuo; Katsuta, Shigeru

2003-05-01

Isometric torque and the cross-sectional area (CSA) of the quadriceps femoris muscle (QF) were measured twice at an interval of 18 months in seven junior Olympic weight lifters (aged 15.5-17.1 years at the start of the study) to investigate the growth trend of this muscle group in junior athletes specializing in strength and power events. The CSAs of the QF and its four constituent muscles were determined at 30% (proximal to the knee), 50%, and 70% of femur length (Fl) using a magnetic resonance imaging method. Only at 30%Fl were significant increases found in the CSAs of the QF and all constituent muscles, except for the rectus femoris. At this level, the CSA of the vastus medialis relative to the QF decreased significantly, suggesting a predominant hypertrophy in the vastus intermedius and vastus lateralis muscles. Isometric torque during knee extension increased significantly compared, to the CSA for the QF measured at the three levels. Thus, the present results indicate that, at least at high school age, the QF for junior Olympic weight lifters is characterized by a preferential hypertrophy at the level proximal to the knee joint, with an increase in knee extension torque relative to the CSA.

Classifying Lower Extremity Muscle Fatigue during Walking using Machine Learning and Inertial Sensors

PubMed Central

Zhang, Jian; Lockhart, Thurmon E.; Soangra, Rahul

2013-01-01

Fatigue in lower extremity musculature is associated with decline in postural stability, motor performance and alters normal walking patterns in human subjects. Automated recognition of lower extremity muscle fatigue condition may be advantageous in early detection of fall and injury risks. Supervised machine learning methods such as Support Vector Machines (SVM) have been previously used for classifying healthy and pathological gait patterns and also for separating old and young gait patterns. In this study we explore the classification potential of SVM in recognition of gait patterns utilizing an inertial measurement unit associated with lower extremity muscular fatigue. Both kinematic and kinetic gait patterns of 17 participants (29±11 years) were recorded and analyzed in normal and fatigued state of walking. Lower extremities were fatigued by performance of a squatting exercise until the participants reached 60% of their baseline maximal voluntary exertion level. Feature selection methods were used to classify fatigue and no-fatigue conditions based on temporal and frequency information of the signals. Additionally, influences of three different kernel schemes (i.e., linear, polynomial, and radial basis function) were investigated for SVM classification. The results indicated that lower extremity muscle fatigue condition influenced gait and loading responses. In terms of the SVM classification results, an accuracy of 96% was reached in distinguishing the two gait patterns (fatigue and no-fatigue) within the same subject using the kinematic, time and frequency domain features. It is also found that linear kernel and RBF kernel were equally good to identify intra-individual fatigue characteristics. These results suggest that intra-subject fatigue classification using gait patterns from an inertial sensor holds considerable potential in identifying “at-risk” gait due to muscle fatigue. PMID:24081829

Skeletal muscle fatigue precedes the slow component of oxygen uptake kinetics during exercise in humans.

PubMed

Cannon, Daniel T; White, Ailish C; Andriano, Melina F; Kolkhorst, Fred W; Rossiter, Harry B

2011-02-01

The mechanisms determining exercise intolerance are poorly understood. A reduction in work efficiency in the form of an additional energy cost and oxygen requirement occurs during high-intensity exercise and contributes to exercise limitation. Muscle fatigue and subsequent recruitment of poorly efficient muscle fibres has been proposed to mediate this decline. These data demonstrate in humans, that muscle fatigue, generated in the initial minutes of exercise, is correlated with the increasing energy demands of high-intensity exercise. Surprisingly, however, while muscle fatigue reached a plateau, oxygen uptake continued to increase throughout 8 min of exercise. This suggests that additional recruitment of inefficient muscle fibres may not be the sole mechanism contributing to the decline in work efficiency during high-intensity exercise.

Muscle mass and composition of the hip, thigh and abdominal muscles in women with and without hip osteoarthritis.

PubMed

Fukumoto, Yoshihiro; Ikezoe, Tome; Tateuchi, Hiroshige; Tsukagoshi, Rui; Akiyama, Haruhiko; So, Kazutaka; Kuroda, Yutaka; Yoneyama, Tomohide; Ichihashi, Noriaki

2012-09-01

The objective of this study was to compare muscle mass and composition between individuals with and without hip osteoarthritis. Twenty-four women with hip osteoarthritis (OA group) and 16 healthy women (healthy group) participated in this study. Muscle thickness (MT) and echo intensity (EI) were measured as indices of muscle mass and composition, respectively, using ultrasound imaging. Seven muscles were examined: gluteus maximus, gluteus medius, quadriceps femoris, rectus abdominis, external oblique, internal oblique and transversus abdominis. MT of only quadriceps femoris in the OA group was significantly thinner than that in the healthy group. EIs of gluteus medius, quadriceps femoris and rectus abdominis were significantly higher in the OA group than those in the healthy group. Thus, actual contractile tissue of gluteus medius and rectus abdominis substantially decreased, although muscle mass was similar, whereas both quantitative and qualitative changes occurred in quadriceps femoris in patients with hip OA. Copyright © 2012 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

EFFECTS OF AGE AND ACUTE MUSCLE FATIGUE ON REACTIVE POSTURAL CONTROL IN HEALTHY ADULTS

PubMed Central

Papa, Evan V.; Foreman, K. Bo; Dibble, Lee E.

2015-01-01

BACKGROUND Falls can cause moderate to severe injuries such as hip fractures and head trauma in older adults. While declines in muscle strength and sensory function contribute to increased falls in older adults, skeletal muscle fatigue is often overlooked as an additional contributor to fall risk. The purpose of this investigation was to examine the effects of acute lower extremity muscle fatigue and age on reactive postural control in healthy adults. METHODS A sample of 16 individuals participated in this study (8 healthy older adults and 8 healthy young persons). Whole body kinematic and kinetic data were collected during anterior and posterior reproducible fall tests before (T0) and immediately after (T1) eccentric muscle fatiguing exercise, as well as after 15-minutes (T15) and 30-minutes (T30) of rest. FINDINGS Lower extremity joint kinematics of the stepping limb during the support (landing) phase of the anterior fall were significantly altered by the presence of acute muscle fatigue. Step velocity was significantly decreased during the anterior falls. Statistically significant main effects of age were found for step length in both fall directions. Effect sizes for all outcomes were small. No statistically significant interaction effects were found. INTERPRETATION Muscle fatigue has a measurable effect on lower extremity joint kinematics during simulated falls. These alterations appear to resolve within 15 minutes of recovery. The above deficits, coupled with a reduced step length, may help explain the increased fall risk in older adults. PMID:26351001

Effects of age and acute muscle fatigue on reactive postural control in healthy adults.

PubMed

Papa, Evan V; Foreman, K Bo; Dibble, Leland E

2015-12-01

Falls can cause moderate to severe injuries such as hip fractures and head trauma in older adults. While declines in muscle strength and sensory function contribute to increased falls in older adults, skeletal muscle fatigue is often overlooked as an additional contributor to fall risk. The purpose of this investigation was to examine the effects of acute lower extremity muscle fatigue and age on reactive postural control in healthy adults. A sample of 16 individuals participated in this study (8 healthy older adults and 8 healthy young persons). Whole body kinematic and kinetic data were collected during anterior and posterior reproducible fall tests before (T0) and immediately after (T1) eccentric muscle fatiguing exercise, as well as after 15-min (T15) and 30-min (T30) of rest. Lower extremity joint kinematics of the stepping limb during the support (landing) phase of the anterior fall were significantly altered by the presence of acute muscle fatigue. Step velocity was significantly decreased during the anterior falls. Statistically significant main effects of age were found for step length in both fall directions. Effect sizes for all outcomes were small. No statistically significant interaction effects were found. Muscle fatigue has a measurable effect on lower extremity joint kinematics during simulated falls. These alterations appear to resolve within 15 min of recovery. The above deficits, coupled with a reduced step length, may help explain the increased fall risk in older adults. Copyright © 2015 Elsevier Ltd. All rights reserved.

Ubiquinol reduces muscle wasting but not fatigue in tumor-bearing mice.

PubMed

Clark, Yvonne Y; Wold, Loren E; Szalacha, Laura A; McCarthy, Donna O

2015-05-01

Fatigue is the most common and distressing symptom reported by cancer patients during and after treatment. Tumor growth increases oxidative stress and cytokine production, which causes skeletal muscle wasting and cardiac dysfunction. The purpose of this study was to determine whether treatment with the antioxidant ubiquinol improves muscle mass, cardiac function, and behavioral measures of fatigue in tumor-bearing mice. Adult female mice were inoculated with colon26 tumor cells. Half the control and tumor-bearing mice were administered ubiquinol (500 mg/kg/day) in their drinking water. Voluntary wheel running (i.e., voluntary running activity [VRA]) and grip strength were measured at Days 0, 8, 14, and 17 of tumor growth. Cardiac function was measured using echocardiography on Day 18 or 19. Biomarkers of inflammation, protein degradation, and oxidative stress were measured in serum and heart and gastrocnemius tissue. VRA and grip strength progressively declined in tumor-bearing mice. Muscle mass and myocardial diastolic function were decreased, and expression of proinflammatory cytokines was increased in serum and muscle and heart tissue on Day 19 of tumor growth. Oxidative stress was present only in the heart, while biomarkers of protein degradation were increased only in the gastrocnemius muscle. Ubiquinol increased muscle mass in the tumor-bearing and control animals but had no effect on the expression of biomarkers of inflammation, protein degradation, or oxidative stress or on behavioral measures of fatigue. © The Author(s) 2014.

Performance Demands in Softball Pitching: A Comprehensive Muscle Fatigue Study.

PubMed

Corben, Jeffrey S; Cerrone, Sara A; Soviero, Julie E; Kwiecien, Susan Y; Nicholas, Stephen J; McHugh, Malachy P

2015-08-01

Monitoring pitch count is standard practice in minor league baseball but not in softball because of the perception that fast-pitch softball pitching is a less stressful motion. To examine muscle fatigue after fast-pitch softball performances to provide an assessment of performance demand. Descriptive laboratory study. Bilateral strength measurements (handheld dynamometer) were made on 19 female softball pitchers (mean age [±SD], 15.2 ± 1.2 years) before and after pitching a game (mean number of pitches, 99 ± 21; mean innings pitched, 5 ± 1). A total of 20 tests were performed on the dominant and nondominant sides: forearm (grip, wrist flexion/extension, pronation/supination, elbow flexion/extension), shoulder (flexion, abduction/adduction, external/internal rotation, empty can test), scapula (middle/lower trapezius, rhomboid), and hip (hip flexion/extension, abduction/adduction). Fatigue (percentage strength loss) was categorized based on bilateral versus unilateral presentation using paired t tests: bilateral symmetric (significant on dominant and nondominant and not different between sides), bilateral asymmetric (significant on dominant and nondominant but significantly greater on dominant), unilateral asymmetric (significant on dominant only and significantly greater than nondominant), or unilateral equivocal (significant on dominant only but not different from nondominant). Bilateral symmetric fatigue was evident for all hip (dominant, 19.3%; nondominant, 15.2%) and scapular tests (dominant, 19.2%; nondominant, 19.3%). In general, shoulder tests exhibited bilateral asymmetric fatigue (dominant, 16.9%; nondominant, 11.6%). Forearm tests were more variable, with bilateral symmetric fatigue in the elbow flexors (dominant, 22.5%; nondominant, 19.2%), and wrist flexors (dominant, 21.6%; nondominant, 19.0%), bilateral asymmetric fatigue in the supinators (dominant, 21.8%; nondominant, 15.5%), unilateral asymmetric fatigue in the elbow extensors (dominant, 22

Normal paraspinal muscle electromyographic fatigue characteristics in patients with primary fibromyalgia.

PubMed

Stokes, M J; Colter, C; Klestov, A; Cooper, R G

1993-08-01

Paraspinal muscle fatigue mechanisms were compared in 14 primary fibromyalgia patients and 14 age and sex matched normal subjects using a standardized 60-s isometric endurance test of the paraspinal muscles, during which surface integrated electromyographic (IEMG) activity was recorded. Fatigue-induced IEMG increases were similar for both groups during the initial 40 s (up to 112 +/- 20% and 111 +/- 6% of initial values in patients and normal subjects respectively). Thereafter, IEMG fell significantly in patients (P < 0.05) but only slightly in controls, so that at 58 s IEMG was 102 +/- 13% in patients and 109 +/- 12% in controls. If patients were divided according to body mass index (BMI, range 19-25 in controls) those with a BMI < 26 (n = 5) showed IEMG changes similar to those of control subjects throughout the test, while obese patients with BMI > 26 (n = 9) showed greater IEMG declines after 40 s than either normal subjects or in the fibromyalgia group as a whole. Paraspinal muscle fatigue mechanisms appear normal in primary fibromyalgia patients. Isometric force maintenance in overweight patients, despite IEMG declines, illustrates the action of intrinsic fatigue resistance mechanisms which were presumably utilized to a greater extent in these patients to cope with the extra load.

Endurance and fatigue characteristics in the neck muscles during sub-maximal isometric test in patients with cervical radiculopathy.

PubMed

Halvorsen, Marie; Abbott, Allan; Peolsson, Anneli; Dedering, Åsa

2014-03-01

The aim of the study was to compare myoelectric manifestation in neck muscle endurance and fatigue characteristics during sub-maximal isometric endurance test in patients with cervical radiculopathy and asymptomatic subjects. An additional aim was to explore associations between primary neck muscle endurance, myoelectric fatigability, and self-rated levels of fatigue, pain and subjective health measurements in patients with cervical radiculopathy. Muscle fatigue in the ventral and dorsal neck muscles was assessed in patients with cervical radiculopathy and in an asymptomatic group during an isometric neck muscle endurance test in prone and supine. 46 patients and 34 asymptomatic subjects participated. Surface electromyography signals were recorded from the sternocleidomastoid, cervical paraspinal muscles and upper and middle trapezius bilaterally during the endurance test. Subjective health measurements were assessed with questionnaires. The results showed altered neck muscle endurance in several of the muscles investigated with greater negative median frequency slope, greater variability, side imbalance, lower endurance time and higher experience of fatigue among the cervical radiculopathy patients compared with healthy subjects. Endurance times were significantly lower in both prone and in supine positions between the patients compared to asymptomatic subjects. During the neck muscle endurance test, fatigues in the upper trapezius muscles during the prone test and in the sternocleidomastoid muscles during the supine test were of more importance than self-perceived pain, fatigue, disability and kinesiophobia in predicting neck muscle endurance (NME). NME testing in the primary neck muscles seems to be an important factor to take into consideration in rehabilitation.

Effects of the forearm support band on wrist extensor muscle fatigue.

PubMed

Knebel, P T; Avery, D W; Gebhardt, T L; Koppenhaver, S L; Allison, S C; Bryan, J M; Kelly, A

1999-11-01

A crossover experimental design with repeated measures. To determine whether the forearm support band alters wrist extensor muscle fatigue. Fatigue of the wrist extensor muscles is thought to be a contributing factor in the development of lateral epicondylitis. The forearm support band is purported to reduce or prevent symptoms of lateral epicondylitis but the mechanism of action is unknown. Fifty unimpaired subjects (36 men, 14 women; mean age = 29 +/- 6 years) were tested with and without a forearm support band before and after a fatiguing bout of exercise. Peak wrist extension isometric force, peak isometric grip force, and median power spectral frequency for wrist extensor electromyographic activity were measured before and after exercise and with and without the forearm support band. A 2 x 2 repeated measures multivariate analysis of variance was used to analyze the data, followed by univariate analysis of variance and Tukey's multiple comparison tests. Peak wrist extension isometric force, peak grip isometric force, and median power spectral frequency were all reduced after exercise. However, there was a significant reduction in peak grip isometric force and peak wrist extension isometric force values for the with-forearm support band condition (grip force 28%, wrist extension force 26%) compared to the without-forearm support band condition (grip force 18%, wrist extension force 15%). Wearing the forearm support band increased the rate of fatigue in unimpaired individuals. Our findings do not support the premise that wearing the forearm support band reduces muscle fatigue in the wrist extensors.

Influence of fatigue and velocity on the latency and recruitment order of scapular muscles.

PubMed

Mendez-Rebolledo, Guillermo; Gatica-Rojas, Valeska; Guzman-Muñoz, Eduardo; Martinez-Valdes, Eduardo; Guzman-Venegas, Rodrigo; Berral de la Rosa, Francisco Jose

2018-07-01

To determine the influence of velocity and fatigue on scapular muscle activation latency and recruitment order during a voluntary arm raise task, in healthy individuals. Cross-sectional study. University laboratory. Twenty three male adults per group (high-velocity and low-velocity). Onset latency of scapular muscles [Anterior deltoid (AD), lower trapezius (LT), middle trapezius (MT), upper trapezius (UT), and serratus anterior (SA)] was assessed by surface electromyography. The participants were assigned to one of two groups: low-velocity or high-velocity. Both groups performed a voluntary arm raise task in the scapular plane under two conditions: no-fatigue and fatigue. The UT showed early activation (p < 0.01) in the fatigue condition when performing the arm raise task at a high velocity. At a low velocity and with no muscular fatigue, the recruitment order was MT, LT, SA, AD, and UT. However, the recruitment order changed in the high-velocity with muscular fatigue condition, since the recruitment order was UT, AD, SA, LT, and MT. The simultaneous presence of fatigue and high-velocity in an arm raise task is associated with a decrease in the UT activation latency and a modification of the recruitment order of scapular muscles. Copyright © 2018 Elsevier Ltd. All rights reserved.

Influence of fatigue on upper limb muscle activity and performance in tennis.

PubMed

Rota, Samuel; Morel, Baptiste; Saboul, Damien; Rogowski, Isabelle; Hautier, Christophe

2014-02-01

The study examined the fatigue effect on tennis performance and upper limb muscle activity. Ten players were tested before and after a strenuous tennis exercise. Velocity and accuracy of serve and forehand drives, as well as corresponding surface electromyographic (EMG) activity of eight upper limb muscles were measured. EMG and force were also evaluated during isometric maximal voluntary contractions (IMVC). Significant decreases were observed after exercise in serve accuracy (-11.7%) and velocity (-4.5%), forehand accuracy (-25.6%) and consistency (-15.6%), as well as pectoralis major (PM) and flexor carpi radialis (FCR) IMVC strength (-13.0% and -8.2%, respectively). EMG amplitude decreased for PM and FCR in serve, forehand and IMVC, and for extensor carpi radialis in forehand. No modification was observed in EMG activation timing during strokes or in EMG frequency content during IMVC. Several hypotheses can be put forward to explain these results. First, muscle fatigue may induce a reduction in activation level of PM and forearm muscles, which could decrease performance. Second, conscious or subconscious strategies could lead to a redistribution of muscle activity to non-fatigued muscles in order to protect the organism and/or limit performance losses. Otherwise, the modifications of EMG activity could also illustrate the strategies adopted to manage the speed-accuracy trade-off in such a complex task. Copyright © 2013 Elsevier Ltd. All rights reserved.

The effect of elbow flexor fatigue on spine kinematics and muscle activation in response to sudden loading at the hands.

PubMed

Zwambag, Derek P; Freeman, Nikole E; Brown, Stephen H M

2015-04-01

Sudden loads, originating at either the hands or the feet, can cause injury to spine structures. As muscles are primarily responsible for stabilization following a perturbation, the effect of spine muscle fatigue in this context has been well investigated. However, the effect of fatigue of arm muscles, which can help control perturbations originating at the hands, on the spine is unknown. The purpose of this study was to determine if the magnitude of spine flexion or the pre-activation, reflex amplitude, and reflex latency of spine muscles were altered by elbow flexor fatigue during a sudden loading (6.8 kg) perturbation at the hands. Elbow flexor fatigue was induced by an isometric 30% maximal elbow flexion moment until failure. Results demonstrate that spine kinematics were not altered in the presence of elbow flexor fatigue. Small magnitude differences in trunk muscle pre- and peak activation indicate that the presence of elbow flexor fatigue does not necessitate substantially greater spine muscle action under the tested conditions. Despite fatigued elbow flexors, the arm muscles were sufficiently able to control the perturbation. Interestingly, 5/14 participants demonstrated altered reflex latencies in all observed muscles that lasted up to 10 min after the fatiguing task. Copyright © 2015 Elsevier Ltd. All rights reserved.

Gear Shifting of Quadriceps during Isometric Knee Extension Disclosed Using Ultrasonography.

PubMed

Zhang, Shu; Huang, Weijian; Zeng, Yu; Shi, Wenxiu; Diao, Xianfen; Wei, Xiguang; Ling, Shan

2018-01-01

Ultrasonography has been widely employed to estimate the morphological changes of muscle during contraction. To further investigate the motion pattern of quadriceps during isometric knee extensions, we studied the relative motion pattern between femur and quadriceps under ultrasonography. An interesting observation is that although the force of isometric knee extension can be controlled to change almost linearly, femur in the simultaneously captured ultrasound video sequences has several different piecewise moving patterns. This phenomenon is like quadriceps having several forward gear ratios like a car starting from rest towards maximal voluntary contraction (MVC) and then returning to rest. Therefore, to verify this assumption, we captured several ultrasound video sequences of isometric knee extension and collected the torque/force signal simultaneously. Then we extract the shapes of femur from these ultrasound video sequences using video processing techniques and study the motion pattern both qualitatively and quantitatively. The phenomenon can be seen easier via a comparison between the torque signal and relative spatial distance between femur and quadriceps. Furthermore, we use cluster analysis techniques to study the process and the clustering results also provided preliminary support to the conclusion that, during both ramp increasing and decreasing phases, quadriceps contraction may have several forward gear ratios relative to femur.

Muscle vibration sustains motor unit firing rate during submaximal isometric fatigue in humans

PubMed Central

Griffin, L; Garland, S J; Ivanova, T; Gossen, E R

2001-01-01

In keeping with the ‘muscular wisdom hypothesis’, many studies have documented that the firing rate of the majority of motor units decreased during fatiguing isometric contractions. The present study investigated whether the application of periodic muscle vibration, which strongly activates muscle spindles, would alter the modulation of motor unit firing rate during submaximal fatiguing isometric contractions. Thirty-three motor units from the lateral head of the triceps brachii muscle were recorded from 10 subjects during a sustained isometric 20 % maximal voluntary contraction (MVC) of the elbow extensors. Vibration was interposed on the contraction for 2 s every 10 s. Twenty-two motor units were recorded from the beginning of the fatigue task. The discharge rate of the majority of motor units remained constant (12/22) or increased (4/22) with fatigue. Six motor units demonstrated a reduction in discharge rate that later returned toward initial values; these motor units had higher initial discharge rates than the other 16 motor units. In a second series of experiments, four subjects held a sustained isometric 20 % MVC for 2 min and then vibration was applied as above for the remainder of the contraction. In this case, motor units initially demonstrated a decrease in firing rate that increased after the vibration was applied. Thus muscle spindle disfacilitation of the motoneurone pool may be associated with the decline of motor unit discharge rate observed during the first 2 min of the contraction. In a third set of experiments, seven subjects performed the main experiment on one occasion and repeated the fatigue task without vibration on a second occasion. Neither the endurance time of the fatiguing contraction nor the MVC torque following fatigue was affected by the application of vibration. This finding calls into question the applicability of the muscular wisdom hypothesis to submaximal contractions. PMID:11559785

Muscle vibration sustains motor unit firing rate during submaximal isometric fatigue in humans.

PubMed

Griffin, L; Garland, S J; Ivanova, T; Gossen, E R

2001-09-15

1. In keeping with the 'muscular wisdom hypothesis', many studies have documented that the firing rate of the majority of motor units decreased during fatiguing isometric contractions. The present study investigated whether the application of periodic muscle vibration, which strongly activates muscle spindles, would alter the modulation of motor unit firing rate during submaximal fatiguing isometric contractions. 2. Thirty-three motor units from the lateral head of the triceps brachii muscle were recorded from 10 subjects during a sustained isometric 20 % maximal voluntary contraction (MVC) of the elbow extensors. Vibration was interposed on the contraction for 2 s every 10 s. Twenty-two motor units were recorded from the beginning of the fatigue task. The discharge rate of the majority of motor units remained constant (12/22) or increased (4/22) with fatigue. Six motor units demonstrated a reduction in discharge rate that later returned toward initial values; these motor units had higher initial discharge rates than the other 16 motor units. 3. In a second series of experiments, four subjects held a sustained isometric 20 % MVC for 2 min and then vibration was applied as above for the remainder of the contraction. In this case, motor units initially demonstrated a decrease in firing rate that increased after the vibration was applied. Thus muscle spindle disfacilitation of the motoneurone pool may be associated with the decline of motor unit discharge rate observed during the first 2 min of the contraction. 4. In a third set of experiments, seven subjects performed the main experiment on one occasion and repeated the fatigue task without vibration on a second occasion. Neither the endurance time of the fatiguing contraction nor the MVC torque following fatigue was affected by the application of vibration. This finding calls into question the applicability of the muscular wisdom hypothesis to submaximal contractions.

The effects of trunk extensor and abdominal muscle fatigue on postural control and trunk proprioception in young, healthy individuals.

PubMed

Larson, Dennis J; Brown, Stephen H M

2018-02-01

The purpose of this study was to induce both trunk extensor and abdominal muscle fatigue, on separate occasions, and compare their effects on standing postural control and trunk proprioception, as well as look at the effects of a recovery period on these outcome measures. A total of 20 individuals participated, with 10 (5 males and 5 females) completing either a standing postural control or lumbar axial repositioning protocol. Participants completed their randomly assigned protocol on two occasions, separated by at least 4  days, with either their trunk extensor or abdominal muscles being fatigued on either day. Postural control centre of pressure variables and trunk proprioception errors were compared pre- and post-fatigue. Results showed that both trunk extensor and abdominal muscle fatigue significantly degraded standing postural control immediately post-fatigue, with recovery occurring within 2 min post-fatigue. In general, these degradative effects on postural control appeared to be greater when the trunk extensor muscles were fatigued compared to the abdominal muscles. No statistically significant changes in trunk proprioception were found after either fatigue protocol. The present findings demonstrate our body's ability to quickly adapt and reweight somatosensory information to maintain postural control and trunk proprioception, as well as illustrate the importance of considering the abdominal muscles, along with the trunk extensor muscles, when considering the impact of fatigue on trunk movement and postural control. Copyright © 2017 Elsevier B.V. All rights reserved.

Measuring the interactions between different locations in a muscle to monitor localized muscle fatigue.

PubMed

Bingham, Adrian; Arjunan, Sridhar P; Kumar, Dinesh K

2017-07-01

In this study we investigated a technique for estimating the progression of localized muscle fatigue. This technique measures the dependence between motor units using high density surface electromyogram (HD-sEMG) and is based on the Normalized Mutual Information (NMI) measure. The NMI between every pair combination of the electrode array is computed to measure the interactions between electrodes. Participants in the experiment had an array of 64 electrodes (16 by 4) placed over the TA of their dominate leg such that the columns of the array ran parallel with the muscle fibers. The HD-sEMG was recorded whilst the participants maintained an isometric dorsiflexion with their dominate foot until task failure at 40% and 80% of their maximum voluntary contraction (MVC). The interactions between different locations over the muscle were computed using the recorded HD-sEMG signals. The results show that the average interactions between various locations over the TA significantly increased during fatigue at both levels of contraction. This can be attributed to the dependence in the motor units.

Tumor Growth Increases Neuroinflammation, Fatigue and Depressive-like Behavior Prior to Alterations in Muscle Function

PubMed Central

Norden, Diana M.; Bicer, Sabahattin; Clark, Yvonne; Jing, Runfeng; Henry, Christopher J.; Wold, Loren E.; Reiser, Peter J.; Godbout, Jonathan P.; McCarthy, Donna O.

2014-01-01

Cancer patients frequently suffer from fatigue, a complex syndrome associated with loss of muscle mass, weakness, and depressed mood. Cancer-related fatigue (CRF) can be present at the time of diagnosis, during treatment, and persists for years after treatment. CRF negatively influences quality of life, limits functional independence, and is associated with decreased survival in patients with incurable disease. Currently there are no effective treatments to reduce CRF. The aim of this study was to use a mouse model of tumor growth and discriminate between two main components of fatigue: loss of muscle mass/function and altered mood/motivation. Here we show that tumor growth increased fatigue- and depressive-like behaviors, and reduced body and muscle mass. Decreased voluntary wheel running activity (VWRA) and increased depressive-like behavior in the forced swim and sucrose preference tests were evident in tumor-bearing mice within the first two weeks of tumor growth and preceded the loss of body and muscle mass. At three weeks, tumor-bearing mice had reduced grip strength but this was not associated with altered expression of myosin isoforms or impaired contractile properties of muscles. These increases in fatigue and depressive-like behaviors were paralleled by increased expression of IL-1β mRNA in the cortex and hippocampus. Minocycline administration reduced tumor-induced expression of IL-1β in the brain, reduced depressive-like behavior, and improved grip strength without altering muscle mass. Taken together, these results indicate that neuroinflammation and depressed mood, rather than muscle wasting, contribute to decreased voluntary activity and precede major changes in muscle contractile properties with tumor growth. PMID:25102452

Tumor growth increases neuroinflammation, fatigue and depressive-like behavior prior to alterations in muscle function.

PubMed

Norden, Diana M; Bicer, Sabahattin; Clark, Yvonne; Jing, Runfeng; Henry, Christopher J; Wold, Loren E; Reiser, Peter J; Godbout, Jonathan P; McCarthy, Donna O

2015-01-01

Cancer patients frequently suffer from fatigue, a complex syndrome associated with loss of muscle mass, weakness, and depressed mood. Cancer-related fatigue (CRF) can be present at the time of diagnosis, during treatment, and persists for years after treatment. CRF negatively influences quality of life, limits functional independence, and is associated with decreased survival in patients with incurable disease. Currently there are no effective treatments to reduce CRF. The aim of this study was to use a mouse model of tumor growth and discriminate between two main components of fatigue: loss of muscle mass/function and altered mood/motivation. Here we show that tumor growth increased fatigue- and depressive-like behaviors, and reduced body and muscle mass. Decreased voluntary wheel running activity (VWRA) and increased depressive-like behavior in the forced swim and sucrose preference tests were evident in tumor-bearing mice within the first two weeks of tumor growth and preceded the loss of body and muscle mass. At three weeks, tumor-bearing mice had reduced grip strength but this was not associated with altered expression of myosin isoforms or impaired contractile properties of muscles. These increases in fatigue and depressive-like behaviors were paralleled by increased expression of IL-1β mRNA in the cortex and hippocampus. Minocycline administration reduced tumor-induced expression of IL-1β in the brain, reduced depressive-like behavior, and improved grip strength without altering muscle mass. Taken together, these results indicate that neuroinflammation and depressed mood, rather than muscle wasting, contribute to decreased voluntary activity and precede major changes in muscle contractile properties with tumor growth. Copyright © 2014 Elsevier Inc. All rights reserved.

Knee joint laxity does not moderate the relationship between quadriceps strength and physical function in knee osteoarthritis patients: A cross-sectional study.

PubMed

Altubasi, Ibrahim M

2018-06-07

Knee osteoarthritis is a common and a disabling musculoskeletal disorder. Patients with knee osteoarthritis have activity limitations which are linked to the strength of the quadriceps muscle. Previous research reported that the relationship between quadriceps muscle strength and physical function is moderated by the level of knee joint frontal plane laxity. The purpose of the current study is to reexamine the moderation effect of the knee joint laxity as measured by stress radiographs on the relationship between quadriceps muscle strength and physical function. One-hundred and sixty osteoarthritis patients participated in this cross-sectional study. Isometric quadriceps muscle strength was measured using an isokinetic dynamometer. Self-rated and performance-based physical function were measured using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) physical function subscale and Get Up and Go test, respectively. Stress radiographs which were taken while applying varus and valgus loads to knee using the TELOS device. Knee joint laxity was determined by measuring the distance between joint surfaces on the medial and lateral sides. Hierarchical multiple regression models were constructed to study the moderation effect of laxity on the strength function relationship. Two regression models were constructed for self-rated and performance-based function. After controlling for demographics, strength contributed significantly in the models. The addition of laxity and laxity-strength interaction did not add significant contributions in the regression models. Frontal plane knee joint laxity measured by stress radiographs does not moderate the relationship between quadriceps muscle strength and physical function in patients with osteoarthritis. Copyright © 2018 Elsevier B.V. All rights reserved.

Lean muscle volume of the thigh has a stronger relationship with muscle power than muscle strength in women with knee osteoarthritis.

PubMed

Davison, Michael J; Maly, Monica R; Keir, Peter J; Hapuhennedige, Sandani M; Kron, Amie T; Adachi, Jonathan D; Beattie, Karen A

2017-01-01

Thigh lean muscle and intramuscular fat have been implicated in the impairment of physical function observed in people with knee osteoarthritis. We investigated the relationships of quadriceps and hamstrings intramuscular fat fraction and lean muscle volume with muscle power and strength, controlling for neuromuscular activation, and physical performance in women with knee OA. Women (n=20) 55years or older with symptomatic, radiographic knee osteoarthritis underwent a 3.0T magnetic resonance imaging scan of the thigh of their most symptomatic knee. Axial fat-separated images were analyzed using software to quantify intramuscular fat and lean muscle volumes of the quadriceps and hamstrings. To quantify strength and power of the knee extensors and flexors, participants performed maximum voluntary isometric contraction and isotonic knee extensions and flexions, respectively. Electromyography of the quadriceps and hamstrings was measured. Participants also completed five physical performance tests. Quadriceps and hamstrings lean muscle volumes were related to isotonic knee extensor (B=0.624; p=0.017) and flexor (B=1.518; p=0.032) power, but not knee extensor (B=0.001; p=0.615) or flexor (B=0.001; p=0.564) isometric strength. Intramuscular fat fractions were not related to isotonic knee extensor or flexor power, nor isometric strength. No relationships were found between intramuscular fat or lean muscle volume and physical performance. Muscle power may be more sensitive than strength to lean muscle mass in women with knee osteoarthritis. Thigh lean muscle mass, but neither intramuscular nor intermuscular fat, is related to knee extensor and flexor power in women with knee osteoarthritis. Copyright © 2016 Elsevier Ltd. All rights reserved.

Major League Baseball pace-of-play rules and their influence on predicted muscle fatigue during simulated baseball games.

PubMed

Sonne, Michael W L; Keir, Peter J

2016-11-01

Major League Baseball (MLB) has proposed rule changes to speed up baseball games. Reducing the time between pitches may impair recovery from fatigue. Fatigue is a known precursor to injury and may jeopardise joint stability. This study examined how fatigue accumulated during baseball games and how different pace of play initiatives may influence fatigue. Pitcher data were retrieved from a public database. A predictive model of muscle fatigue estimated muscle fatigue in 8 arm muscles. A self-selected pace (22.7 s), 12 s pace (Rule 8.04 from the MLB) and a 20 s rest (a pitch clock examined in the 2014 Arizona Fall League (AFL)) were examined. Significantly more muscle fatigue existed in both the AFL and Rule 8.04 conditions, when compared to the self-selected pace condition (5.01 ± 1.73%, 3.95 ± 1.20% and 3.70 ± 1.10% MVC force lost, respectively). Elevated levels of muscle fatigue are predicted in the flexor-pronator mass, which is responsible for providing elbow stability. Reduced effectiveness of the flexor-pronator mass may reduce the active contributions to joint rotational stiffness, increasing strain on the ulnar collateral ligament (UCL) and possibly increasing injury risk.

The relationship between exercise-induced muscle fatigue, arterial blood flow and muscle perfusion after 56 days local muscle unloading.

PubMed

Weber, Tobias; Ducos, Michel; Mulder, Edwin; Beijer, Åsa; Herrera, Frankyn; Zange, Jochen; Degens, Hans; Bloch, Wilhelm; Rittweger, Jörn

2014-05-01

In the light of the dynamic nature of habitual plantar flexor activity, we utilized an incremental isokinetic exercise test (IIET) to assess the work-related power deficit (WoRPD) as a measure for exercise-induced muscle fatigue before and after prolonged calf muscle unloading and in relation to arterial blood flow and muscle perfusion. Eleven male subjects (31 ± 6 years) wore the HEPHAISTOS unloading orthosis unilaterally for 56 days. It allows habitual ambulation while greatly reducing plantar flexor activity and torque production. Endpoint measurements encompassed arterial blood flow, measured in the femoral artery using Doppler ultrasound, oxygenation of the soleus muscle assessed by near-infrared spectroscopy, lactate concentrations determined in capillary blood and muscle activity using soleus muscle surface electromyography. Furthermore, soleus muscle biopsies were taken to investigate morphological muscle changes. After the intervention, maximal isokinetic torque was reduced by 23·4 ± 8·2% (P<0·001) and soleus fibre size was reduced by 8·5 ± 13% (P = 0·016). However, WoRPD remained unaffected as indicated by an unchanged loss of relative plantar flexor power between pre- and postexperiments (P = 0·88). Blood flow, tissue oxygenation, lactate concentrations and EMG median frequency kinematics during the exercise test were comparable before and after the intervention, whereas the increase of RMS in response to IIET was less following the intervention (P = 0·03). In conclusion, following submaximal isokinetic muscle work exercise-induced muscle fatigue is unaffected after prolonged local muscle unloading. The observation that arterial blood flow was maintained may underlie the unchanged fatigability. © 2013 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

Incubating Isolated Mouse EDL Muscles with Creatine Improves Force Production and Twitch Kinetics in Fatigue Due to Reduction in Ionic Strength

PubMed Central

Head, Stewart I.; Greenaway, Bronwen; Chan, Stephen

2011-01-01

Background Creatine supplementation can improve performance during high intensity exercise in humans and improve muscle strength in certain myopathies. In this present study, we investigated the direct effects of acute creatine incubation on isolated mouse fast-twitch EDL muscles, and examined how these effects change with fatigue. Methods and Results The extensor digitorum longus muscle from mice aged 12–14 weeks was isolated and stimulated with field electrodes to measure force characteristics in 3 different states: (i) before fatigue; (ii) immediately after a fatigue protocol; and (iii) after recovery. These served as the control measurements for the muscle. The muscle was then incubated in a creatine solution and washed. The measurement of force characteristics in the 3 different states was then repeated. In un-fatigued muscle, creatine incubation increased the maximal tetanic force. In fatigued muscle, creatine treatment increased the force produced at all frequencies of stimulation. Incubation also increased the rate of twitch relaxation and twitch contraction in fatigued muscle. During repetitive fatiguing stimulation, creatine-treated muscles took 55.1±9.5% longer than control muscles to lose half of their original force. Measurement of weight changes showed that creatine incubation increased EDL muscle mass by 7%. Conclusion Acute creatine application improves force production in isolated fast-twitch EDL muscle, and these improvements are particularly apparent when the muscle is fatigued. One likely mechanism for this improvement is an increase in Ca2+ sensitivity of contractile proteins as a result of ionic strength decreases following creatine incubation. PMID:21850234

Effect of old age on human skeletal muscle force-velocity and fatigue properties

PubMed Central

Callahan, Damien M.

2011-01-01

It is generally accepted that the muscles of aged individuals contract with less force, have slower relaxation rates, and demonstrate a downward shift in their force-velocity relationship. The factors mediating age-related differences in skeletal muscle fatigue are less clear. The present study was designed to test the hypothesis that age-related shifts in the force-velocity relationship impact the fatigue response in a velocity-dependent manner. Three fatigue protocols, consisting of intermittent, maximum voluntary knee extension contractions performed for 4 min, were performed by 11 young (23.5 ± 0.9 yr, mean ± SE) and 10 older (68.9 ± 4.3) women. The older group fatigued less during isometric contractions than the young group (to 71.1 ± 3.7% initial torque and 59.8 ± 2.5%, respectively; P = 0.02), while the opposite was true during contractions performed at a relatively high angular velocity of 270°·s−1 (old: 28.0 ± 3.9% initial power, young: 52.1 ± 6.9%; P < 0.01). Fatigue was not different (P = 0.74) between groups during contractions at an intermediate velocity, which was selected for each participant based on their force-velocity relationship. There was a significant association between force-velocity properties and fatigue induced by the intermediate-velocity fatigue protocol in the older (r = 0.72; P = 0.02) and young (r = 0.63; P = 0.04) groups. These results indicate that contractile velocity has a profound impact on age-related skeletal muscle fatigue resistance and suggest that changes in the force-velocity relationship partially mediate this effect. PMID:21868683

Detection and Alert of muscle fatigue considering a Surface Electromyography Chaotic Model

NASA Astrophysics Data System (ADS)

Herrera, V.; Romero, J. F.; Amestegui, M.

2011-03-01

This work propose a detection and alert algorithm for muscle fatigue in paraplegic patients undergoing electro-therapy sessions. The procedure is based on a mathematical chaotic model emulating physiological signals and Continuous Wavelet Transform (CWT). The chaotic model developed is based on a logistic map that provides suitable data accomplishing some physiological signal class patterns. The CWT was applied to signals generated by the model and the resulting vector was obtained through Total Wavelet Entropy (TWE). In this sense, the presented work propose a viable and practical alert and detection algorithm for muscle fatigue.

Quadriceps Muscles O2 Extraction and EMG Breakpoints during a Ramp Incremental Test

PubMed Central

Iannetta, Danilo; Qahtani, Ahmad; Millet, Guillaume Y.; Murias, Juan M.

2017-01-01

Muscle deoxygenated breakpoint ([HHb]BP) has been found to be associated with other indices of exercise tolerance in the vastus lateralis (VL) muscle but not in the vastus medialis (VM) and rectus femoris (RF). Purpose: To investigate whether the [HHb]BP occurs also in the VM and RF muscles and whether or not it is associated with other physiological indices of exercise tolerance, such as the EMG threshold (EMGt) and the respiratory compensation point (RCP). Methods: Twelve young endurance trained participants performed maximal ramp incremental (RI) cycling tests (25–30 W·min−1 increments). Muscle oxygen extraction and activity as well as ventilatory and gas exchange parameters were measured. After accounting for the mean response time, the oxygen uptake (V·O2) corresponding to the RCP, [HHb]BP, and the EMGt was determined. Results: Peak power output (POpeak) was 359 ± 48 W. Maximal oxygen consumption (V·O2max) was 3.87 ± 0.46 L·min−1. The V·O2 at the RCP was 3.39 ± 0.41 L·min−1. The V·O2 (L·min−1) corresponding to the [HHb]BP and EMGt were: 3.49 ± 0.46 and 3.40 ± 0.44; 3.44 ± 0.61 and 3.43 ± 0.49; 3.59 ± 0.52, and 3.48 ± 0.46 for VL, VM, and RF, respectively. Pearson's correlation between these thresholds ranged from 0.90 to 0.97 (P < 0.05). No difference was found for the absolute V·O2 and the normalized PO (%) at which the thresholds occurred in all three muscles investigated (P > 0.05). Although in eight out of 12 participants, the [HHb]BP in the RF led to a steeper increase instead of leading to a plateau-like response as observed in the VL and VM, the V·O2 at the breakpoints still coincided with that at the RCP. Conclusions: This study demonstrated that local indices of exercise tolerance derived from different portions of the quadriceps are not different to the systemic index of the RCP. PMID:28970805

Recovery of upper limb muscle function in chronic fatigue syndrome with and without fibromyalgia.

PubMed

Ickmans, Kelly; Meeus, Mira; De Kooning, Margot; Lambrecht, Luc; Nijs, Jo

2014-02-01

Chronic fatigue syndrome (CFS) patients frequently complain of muscle fatigue and abnormally slow recovery, especially of the upper limb muscles during and after activities of daily living. Furthermore, disease heterogeneity has not yet been studied in relation to recovery of muscle function in CFS. Here, we examine recovery of upper limb muscle function from a fatiguing exercise in CFS patients with (CFS+FM) and without (CFS-only) comorbid fibromyalgia and compare their results with a matched inactive control group. In this case-control study, 18 CFS-only patients, 30 CFS+FM patients and 30 healthy inactive controls performed a fatiguing upper limb exercise test with subsequent recovery measures. There was no significant difference among the three groups for maximal handgrip strength of the non-dominant hand. A significant worse recovery of upper limb muscle function was found in the CFS+FM, but not in de CFS-only group compared with the controls (P < 0·05). This study reveals, for the first time, delayed recovery of upper limb muscle function in CFS+FM, but not in CFS-only patients. The results underline that CFS is a heterogeneous disorder suggesting that reducing the heterogeneity of the disorder in future research is important to make progress towards a better understanding and uncovering of mechanisms regarding the nature of divers impairments in these patients. © 2013 Stichting European Society for Clinical Investigation Journal Foundation. Published by John Wiley & Sons Ltd.

Prior Heat Stress Effects Fatigue Recovery of the Elbow Flexor Muscles

PubMed Central

Iguchi, Masaki; Shields, Richard K.

2011-01-01

Introduction Long-lasting alterations in hormones, neurotransmitters and stress proteins after hyperthermia may be responsible for the impairment in motor performance during muscle fatigue. Methods Subjects (n = 25) performed a maximal intermittent fatigue task of elbow flexion after sitting in either 73 or 26 deg C to examine the effects of prior heat stress on fatigue mechanisms. Results The heat stress increased the tympanic and rectal temperatures by 2.3 and 0.82 deg C, respectively, but there was full recovery prior to the fatigue task. While prior heat stress had no effects on fatigue-related changes in volitional torque, EMG activity, torque relaxation rate, MEP size and SP duration, prior heat stress acutely increased the pre-fatigue relaxation rate and chronically prevented long-duration fatigue (p < 0.05). Discussion These findings indicate that prior passive heat stress alone does not alter voluntary activation during fatigue, but prior heat stress and exercise produce longer-term protection against long-duration fatigue. PMID:21674526

Fatiguing contractions increase protein S-glutathionylation occupancy in mouse skeletal muscle.

PubMed

Kramer, Philip A; Duan, Jicheng; Gaffrey, Matthew J; Shukla, Anil K; Wang, Lu; Bammler, Theo K; Qian, Wei-Jun; Marcinek, David J

2018-05-23

Protein S-glutathionylation is an important reversible post-translational modification implicated in redox signaling. Oxidative modifications to protein thiols can alter the activity of metabolic enzymes, transcription factors, kinases, phosphatases, and the function of contractile proteins. However, the extent to which muscle contraction induces oxidative modifications in redox sensitive thiols is not known. The purpose of this study was to determine the targets of S-glutathionylation redox signaling following fatiguing contractions. Anesthetized adult male CB6F1 (BALB/cBy × C57BL/6) mice were subjected to acute fatiguing contractions for 15 min using in vivo stimulations. The right (stimulated) and left (unstimulated) gastrocnemius muscleswere collected 60 min after the last stimulation and processed for redox proteomics assay of S-glutathionylation. Using selective reduction with a glutaredoxin enzyme cocktail and resin-assisted enrichment technique, we quantified the levels of site-specific protein S-glutathionylation at rest and following fatiguing contractions. Redox proteomics revealed over 2200 sites of S-glutathionylation modifications, of which 1290 were significantly increased after fatiguing contractions. Muscle contraction leads to the greatest increase in S-glutathionylation in the mitochondria (1.03%) and the smallest increase in the nucleus (0.47%). Regulatory cysteines were significantly S-glutathionylated on mitochondrial complex I and II, GAPDH, MDH1, ACO2, and mitochondrial complex V among others. Similarly, S-glutathionylation of RYR1, SERCA1, titin, and troponin I2 are known to regulate muscle contractility and were significantly S-glutathionylated after just 15 min of fatiguing contractions. The largest fold changes (> 1.6) in the S-glutathionylated proteome after fatigue occurred on signaling proteins such as 14-3-3 protein gamma and MAP2K4, as well as proteins like SERCA1, and NDUV2 of mitochondrial complex I, at previously unknown

The Effects of Vibration and Muscle Fatigue on Trunk Sensorimotor Control in Low Back Pain Patients

PubMed Central

Abboud, Jacques; Nougarou, François; Normand, Martin C.

2015-01-01

Introduction Changes in sensorimotor function and increased trunk muscle fatigability have been identified in patients with chronic low back pain (cLBP). This study assessed the control of trunk force production in conditions with and without local erector spinae muscle vibration and evaluated the influence of muscle fatigue on trunk sensorimotor control. Methods Twenty non-specific cLBP patients and 20 healthy participants were asked to perform submaximal isometric trunk extension torque with and without local vibration stimulation, before and after a trunk extensor muscle fatigue protocol. Constant error (CE), variable error (VE) as well as absolute error (AE) in peak torque were computed and compared across conditions. Trunk extensor muscle activation during isometric contractions and during the fatigue protocol was measured using surface electromyography (sEMG). Results Force reproduction accuracy of the trunk was significantly lower in the patient group (CE = 9.81 ± 2.23 Nm; AE = 18.16 ± 3.97 Nm) than in healthy participants (CE = 4.44 ± 1.68 Nm; AE = 12.23 ± 2.44 Nm). Local erector spinae vibration induced a significant reduction in CE (4.33 ± 2.14 Nm) and AE (13.71 ± 3.45 Nm) mean scores in the patient group. Healthy participants conversely showed a significant increase in CE (8.17 ± 2.10 Nm) and AE (16.29 ± 2.82 Nm) mean scores under vibration conditions. The fatigue protocol induced erector spinae muscle fatigue as illustrated by a significant decrease in sEMG median time-frequency slopes. Following the fatigue protocol, patients with cLBP showed significant decrease in sEMG root mean square activity at L4-5 level and responded in similar manner with and without vibration stimulation in regard to CE mean scores. Conclusions Patients with cLBP have a less accurate force reproduction sense than healthy participants. Local muscle vibration led to significant trunk neuromuscular control improvements in the cLBP patients before and after a muscle

The Effects of Vibration and Muscle Fatigue on Trunk Sensorimotor Control in Low Back Pain Patients.

PubMed

Boucher, Jean-Alexandre; Abboud, Jacques; Nougarou, François; Normand, Martin C; Descarreaux, Martin

2015-01-01

Changes in sensorimotor function and increased trunk muscle fatigability have been identified in patients with chronic low back pain (cLBP). This study assessed the control of trunk force production in conditions with and without local erector spinae muscle vibration and evaluated the influence of muscle fatigue on trunk sensorimotor control. Twenty non-specific cLBP patients and 20 healthy participants were asked to perform submaximal isometric trunk extension torque with and without local vibration stimulation, before and after a trunk extensor muscle fatigue protocol. Constant error (CE), variable error (VE) as well as absolute error (AE) in peak torque were computed and compared across conditions. Trunk extensor muscle activation during isometric contractions and during the fatigue protocol was measured using surface electromyography (sEMG). Force reproduction accuracy of the trunk was significantly lower in the patient group (CE = 9.81 ± 2.23 Nm; AE = 18.16 ± 3.97 Nm) than in healthy participants (CE = 4.44 ± 1.68 Nm; AE = 12.23 ± 2.44 Nm). Local erector spinae vibration induced a significant reduction in CE (4.33 ± 2.14 Nm) and AE (13.71 ± 3.45 Nm) mean scores in the patient group. Healthy participants conversely showed a significant increase in CE (8.17 ± 2.10 Nm) and AE (16.29 ± 2.82 Nm) mean scores under vibration conditions. The fatigue protocol induced erector spinae muscle fatigue as illustrated by a significant decrease in sEMG median time-frequency slopes. Following the fatigue protocol, patients with cLBP showed significant decrease in sEMG root mean square activity at L4-5 level and responded in similar manner with and without vibration stimulation in regard to CE mean scores. Patients with cLBP have a less accurate force reproduction sense than healthy participants. Local muscle vibration led to significant trunk neuromuscular control improvements in the cLBP patients before and after a muscle fatigue protocol. Muscle vibration stimulation

Knee flexion with quadriceps cocontraction: A new therapeutic exercise for the early stage of ACL rehabilitation.

PubMed

Biscarini, Andrea; Contemori, Samuele; Busti, Daniele; Botti, Fabio M; Pettorossi, Vito E

2016-12-08

Quadriceps strengthening exercises designed for the early phase of anterior cruciate ligament (ACL) rehabilitation should limit the anterior tibial translation developed by quadriceps contraction near full knee extension, in order to avoid excessive strain on the healing tissue. We hypothesize that knee-flexion exercises with simultaneous voluntary contraction of quadriceps (voluntary quadriceps cocontraction) can yield considerable levels of quadriceps activation while preventing the tibia from translating forward relative to the femur. Electromyographic activity in quadriceps and hamstring muscles was measured in 20 healthy males during isometric knee-flexion exercises executed near full knee extension with maximal voluntary effort of quadriceps cocontraction and external resistance (R) ranging from 0% to 60% of the 1-repetition maximum (1RM). Biomechanical modeling was applied to derive the shear (anterior/posterior) tibiofemoral force developed in each exercise condition. Isometric knee-flexion exercises with small external resistance (R=10% 1RM) and maximal voluntary effort of quadriceps cocontraction yielded a net posterior (ACL-unloading) tibial pull (P=0.005) and levels of activation of 32%, 50%, and 45% of maximum voluntary isometric contraction, for the rectus femoris, vastus medialis, and vastus lateralis, respectively. This exercise might potentially rank as one of the most appropriate quadriceps strengthening interventions in the early phase of ACL rehabilitation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Development and Applications of a Self-Contained, Non-Invasive EVA Joint Angle and Muscle Fatigue Sensor System

NASA Technical Reports Server (NTRS)

Ranniger, C. U.; Sorenson, E. A.; Akin, D. L.

1995-01-01

The University of Maryland Space Systems Laboratory, as a participant in NASA's INSTEP program, is developing a non-invasive, self-contained sensor system which can provide quantitative measurements of joint angles and muscle fatigue in the hand and forearm. The goal of this project is to develop a system with which hand/forearm motion and fatigue metrics can be determined in various terrestrial and zero-G work environments. A preliminary study of the prototype sensor systems and data reduction techniques for the fatigue measurement system are presented. The sensor systems evaluated include fiberoptics, used to measure joint angle, surface electrodes, which measure the electrical signals created in muscle as it contracts; microphones, which measure the noise made by contracting muscle; and accelerometers, which measure the lateral muscle acceleration during contraction. The prototype sensor systems were used to monitor joint motion of the metacarpophalangeal joint and muscle fatigue in flexor digitorum superficialis and flexor carpi ulnaris in subjects performing gripping tasks. Subjects were asked to sustain a 60-second constant-contraction (isometric) exercise and subsequently to perform a repetitive handgripping task to failure. Comparison of the electrical and mechanical signals of the muscles during the different tasks will be used to evaluate the applicability of muscle signal measurement techniques developed for isometric contraction tasks to fatigue prediction in quasi-dynamic exercises. Potential data reduction schemes are presented.

Expiratory muscle loading increases intercostal muscle blood flow during leg exercise in healthy humans

PubMed Central

Athanasopoulos, Dimitris; Louvaris, Zafeiris; Cherouveim, Evgenia; Andrianopoulos, Vasilis; Roussos, Charis; Zakynthinos, Spyros

2010-01-01

We investigated whether expiratory muscle loading induced by the application of expiratory flow limitation (EFL) during exercise in healthy subjects causes a reduction in quadriceps muscle blood flow in favor of the blood flow to the intercostal muscles. We hypothesized that, during exercise with EFL quadriceps muscle blood flow would be reduced, whereas intercostal muscle blood flow would be increased compared with exercise without EFL. We initially performed an incremental exercise test on eight healthy male subjects with a Starling resistor in the expiratory line limiting expiratory flow to ∼ 1 l/s to determine peak EFL exercise workload. On a different day, two constant-load exercise trials were performed in a balanced ordering sequence, during which subjects exercised with or without EFL at peak EFL exercise workload for 6 min. Intercostal (probe over the 7th intercostal space) and vastus lateralis muscle blood flow index (BFI) was calculated by near-infrared spectroscopy using indocyanine green, whereas cardiac output (CO) was measured by an impedance cardiography technique. At exercise termination, CO and stroke volume were not significantly different during exercise, with or without EFL (CO: 16.5 vs. 15.2 l/min, stroke volume: 104 vs. 107 ml/beat). Quadriceps muscle BFI during exercise with EFL (5.4 nM/s) was significantly (P = 0.043) lower compared with exercise without EFL (7.6 nM/s), whereas intercostal muscle BFI during exercise with EFL (3.5 nM/s) was significantly (P = 0.021) greater compared with that recorded during control exercise (0.4 nM/s). In conclusion, increased respiratory muscle loading during exercise in healthy humans causes an increase in blood flow to the intercostal muscles and a concomitant decrease in quadriceps muscle blood flow. PMID:20507965

Motor Unit Activity during Fatiguing Isometric Muscle Contraction in Hemispheric Stroke Survivors

PubMed Central

McManus, Lara; Hu, Xiaogang; Rymer, William Z.; Suresh, Nina L.; Lowery, Madeleine M.

2017-01-01

Enhanced muscle weakness is commonly experienced following stroke and may be accompanied by increased susceptibility to fatigue. To examine the contributions of central and peripheral factors to isometric muscle fatigue in stroke survivors, this study investigates changes in motor unit (MU) mean firing rate, and action potential duration during, and directly following, a sustained submaximal fatiguing contraction at 30% maximum voluntary contraction (MVC). A series of short contractions of the first dorsal interosseous muscle were performed pre- and post-fatigue at 20% MVC, and again following a 10-min recovery period, by 12 chronic stroke survivors. Individual MU firing times were extracted using surface EMG decomposition and used to obtain the spike-triggered average MU action potential waveforms. During the sustained fatiguing contraction, the mean rate of change in firing rate across all detected MUs was greater on the affected side (-0.02 ± 0.03 Hz/s) than on the less-affected side (-0.004 ± 0.003 Hz/s, p = 0.045). The change in firing rate immediately post-fatigue was also greater on the affected side than less-affected side (-13.5 ± 20 and 0.1 ± 19%, p = 0.04). Mean MU firing rates increased following the recovery period on the less-affected side when compared to the affected side (19.3 ± 17 and 0.5 ± 20%, respectively, p = 0.03). MU action potential duration increased post-fatigue on both sides (10.3 ± 1.2 to 11.2 ± 1.3 ms on the affected side and 9.9 ± 1.7 to 11.2 ± 1.9 ms on the less-affected side, p = 0.001 and p = 0.02, respectively), and changes in action potential duration tended to be smaller in subjects with greater impairment (p = 0.04). This study presents evidence of both central and peripheral fatigue at the MU level during isometric fatiguing contraction for the first time in stroke survivors. Together, these preliminary observations indicate that the response to an isometric fatiguing contraction differs between the affected and less

Comparison of the effects of fatigue on kinematics and muscle activation between men and women after anterior cruciate ligament reconstruction.

PubMed

Lessi, Giovanna Camparis; Silva, Rodrigo Scattone; Serrão, Fábio Viadanna

2018-05-01

Studies comparing the effects of fatigue between men and women after anterior cruciate ligament (ACL) reconstruction are lacking. The purpose of this study was to compare the effects of muscle fatigue on trunk, pelvis and lower limb kinematics and on lower limb muscle activation between male and female athletes who underwent ACL reconstruction. Cross-sectional study. Laboratory setting. Fourteen recreational athletes (7 males and 7 females) with unilateral ACL reconstruction participated of this study. Trunk, pelvis and lower limb kinematics and muscle activation of the vastus lateralis, gluteus medius and gluteus maximus were evaluated during a single-leg drop vertical jump landing before and after a fatigue protocol. Females had greater peak knee abduction after fatigue in relation to before fatigue (P = 0.008), and in relation to men after fatigue (P = 0.011). Also, in females, peak knee abduction was greater in the reconstructed limb in relation to the non-reconstructed limb after fatigue (P = 0.029). Males showed a greater mean amplitude of activation of the vastus lateralis muscle after fatigue in relation to before fatigue (P < 0.001). Muscle fatigue produced kinematic alterations that have been shown to increase the risk for a second ACL injury in female athletes. Copyright © 2018 Elsevier Ltd. All rights reserved.

Dynamic versus isometric electromechanical delay in non-fatigued and fatigued muscle: A combined electromyographic, mechanomyographic, and force approach.

PubMed

Smith, Cory M; Housh, Terry J; Hill, Ethan C; Johnson, Glen O; Schmidt, Richard J

2017-04-01

This study used a combined electromyographic, mechanomyographic, and force approach to identify electromechanical delay (EMD) from the onsets of the electromyographic to force signals (EMD E-F ), onsets of the electromyographic to mechanomyogrpahic signals (EMD E-M ), and onsets of mechanomyographic to force signals (EMD M-F ). The purposes of the current study were to examine: (1) the differences in EMD E-F , EMD E-M , and EMD M-F from the vastus lateralis during maximal, voluntary dynamic (1 repetition maximum [1-RM]) and isometric (maximal voluntary isometric contraction [MVIC]) muscle actions; and (2) the effects of fatigue on EMD E-F , EMD M-F , and EMD E-M . Ten men performed pretest and posttest 1-RM and MVIC leg extension muscle actions. The fatiguing workbout consisted of 70% 1-RM dynamic constant external resistance leg extension muscle actions to failure. The results indicated that there were no significant differences between 1-RM and MVIC EMD E-F , EMD E-M , or EMD M-F. There were, however, significant fatigue-induced increases in EMD E-F (94% and 63%), EMD E-M (107%), and EMD M-F (63%) for both the 1-RM and MVIC measurements. Therefore, these findings demonstrated the effects of fatigue on EMD measures and supported comparisons among studies which examined dynamic or isometric EMD measures from the vastus lateralis using a combined electromyographic, mechanomyographic, and force approach. Copyright © 2017 Elsevier Ltd. All rights reserved.

Volume measurements of individual muscles in human quadriceps femoris using atlas-based segmentation approaches.

PubMed

Le Troter, Arnaud; Fouré, Alexandre; Guye, Maxime; Confort-Gouny, Sylviane; Mattei, Jean-Pierre; Gondin, Julien; Salort-Campana, Emmanuelle; Bendahan, David

2016-04-01

Atlas-based segmentation is a powerful method for automatic structural segmentation of several sub-structures in many organs. However, such an approach has been very scarcely used in the context of muscle segmentation, and so far no study has assessed such a method for the automatic delineation of individual muscles of the quadriceps femoris (QF). In the present study, we have evaluated a fully automated multi-atlas method and a semi-automated single-atlas method for the segmentation and volume quantification of the four muscles of the QF and for the QF as a whole. The study was conducted in 32 young healthy males, using high-resolution magnetic resonance images (MRI) of the thigh. The multi-atlas-based segmentation method was conducted in 25 subjects. Different non-linear registration approaches based on free-form deformable (FFD) and symmetric diffeomorphic normalization algorithms (SyN) were assessed. Optimal parameters of two fusion methods, i.e., STAPLE and STEPS, were determined on the basis of the highest Dice similarity index (DSI) considering manual segmentation (MSeg) as the ground truth. Validation and reproducibility of this pipeline were determined using another MRI dataset recorded in seven healthy male subjects on the basis of additional metrics such as the muscle volume similarity values, intraclass coefficient, and coefficient of variation. Both non-linear registration methods (FFD and SyN) were also evaluated as part of a single-atlas strategy in order to assess longitudinal muscle volume measurements. The multi- and the single-atlas approaches were compared for the segmentation and the volume quantification of the four muscles of the QF and for the QF as a whole. Considering each muscle of the QF, the DSI of the multi-atlas-based approach was high 0.87 ± 0.11 and the best results were obtained with the combination of two deformation fields resulting from the SyN registration method and the STEPS fusion algorithm. The optimal variables for FFD

Acromiohumeral Distance and 3-Dimensional Scapular Position Change After Overhead Muscle Fatigue

PubMed Central

Maenhout, Annelies; Dhooge, Famke; Van Herzeele, Maarten; Palmans, Tanneke; Cools, Ann

2015-01-01

Context: Muscle fatigue due to repetitive and prolonged overhead sports activity is considered an important factor contributing to impingement-related rotator cuff pathologic conditions in overhead athletes. The evidence on scapular and glenohumeral kinematic changes after fatigue is contradicting and prohibits conclusions about how shoulder muscle fatigue affects acromiohumeral distance. Objective: To investigate the effect of a fatigue protocol resembling overhead sports activity on acromiohumeral distance and 3-dimensional scapular position in overhead athletes. Design: Cross-sectional study. Setting: Institutional laboratory. Patients or Other Participants: A total of 29 healthy recreational overhead athletes (14 men, 15 women; age = 22.23 ± 2.82 years, height = 178.3 ± 7.8 cm, mass = 71.6 ± 9.5 kg). Intervention(s) The athletes were tested before and after a shoulder muscle-fatiguing protocol. Main Outcome Measure(s) Acromiohumeral distance was measured using ultrasound, and scapular position was determined with an electromagnetic motion-tracking system. Both measurements were performed at 3 elevation positions (0°, 45°, and 60° of abduction). We used a 3-factor mixed model for data analysis. Results: After fatigue, the acromiohumeral distance increased when the upper extremity was actively positioned at 45° (Δ = 0.78 ± 0.24 mm, P = .002) or 60° (Δ = 0.58 ± 0.23 mm, P = .02) of abduction. Scapular position changed after fatigue to a more externally rotated position at 45° (Δ = 4.97° ± 1.13°, P < .001) and 60° (Δ = 4.61° ± 1.90°, P = .001) of abduction, a more upwardly rotated position at 45° (Δ = 6.10° ± 1.30°, P < .001) and 60° (Δ = 7.20° ± 1.65°, P < .001) of abduction, and a more posteriorly tilted position at 0°, 45°, and 60° of abduction (Δ = 1.98° ± 0.41°, P < .001). Conclusions: After a fatiguing protocol, we found changes in acromiohumeral distance and scapular position that corresponded with an impingement

Blood flow occlusion-related O2 extraction "reserve" is present in different muscles of the quadriceps but greater in deeper regions after ramp-incremental test.

PubMed

Iannetta, Danilo; Okushima, Dai; Inglis, Erin Calaine; Kondo, Narihiko; Murias, Juan M; Koga, Shunsaku

2018-05-03

It was recently demonstrated that an O 2 extraction reserve, as assessed by the near-infrared spectroscopy (NIRS)-derived deoxygenation signal ([HHb]), exists in the superficial region of vastus lateralis (VL) muscle during an occlusion performed at the end of a ramp-incremental test. However, it is unknown whether this reserve is present and/or different in magnitude in other portions and depths of the quadriceps muscles. We tested the hypothesis that O 2 extraction would exist in other regions of this muscle but greater in deep compared to more superficial portions. Superficial and deep VL (VL-s and VL-d, respectively) as well as superficial rectus femoris (RF-s) were monitored by a combination of low- and high- power time resolved (TRS) NIRS. During the occlusion immediately post ramp-incremental test there was a significant overshoot in the [HHb] signal (P<0.05). However, the magnitude of this increase was greater in VL-d (93.2{plus minus}42.9%) compared to VL-s (55.0{plus minus}19.6%) and RF-s (47.8{plus minus}14.0%) (P<0.05). The present study demonstrated that an O2 extraction reserve exists in different pools of active muscle fibers of the quadriceps at the end of a ramp exercise to exhaustion. The greater magnitude in the reserve observed in the deeper portion of VL, however, suggests that this portion of muscle may present a greater surplus of oxygenated blood, likely due to a greater population of slow-twitch fibers. These findings add to the notion that the plateau in the [HHb] signal towards the end of a ramp-incremental exercise does not indicate the upper limit of O 2 extraction.

Comparison of the effect of selected muscle groups fatigue on postural control during bipedal stance in healthy young women.

PubMed

Shirazi, Zahra Rojhani; Jahromi, Fatemeh Nikhalat

2013-09-01

The maintenance of balance is an essential requirement for the performance of daily tasks and sporting activities and muscular fatigue is a factor to impair postural control, so this study was done to compare the effect of selected muscle groups fatigue on postural control during bipedal stance in healthy subjects. Fifteen healthy female students (24.3 ± 2.6 years) completed three testing session with a break period of at least 2 days. During each session, postural control was assessed during two 30-s trials of bipedal stance with eyes close before and after the fatigue protocol. Fatigue protocols were performed by 60% of their unfatigued Maximum Voluntary Contraction of unilateral ankle plantar flexors, bilateral lumbar extensors and bilateral neck extensors. One of the three fatigue protocols was performed on each session. The result showed that fatigue had a significant effect on COP velocity and it increase COP velocity but there was not found any difference in postural sway between muscle groups. Localized muscle fatigue caused deficits in postural control regardless of the location of fatigue. Authors suggest the possibility of the contributions of central mechanisms to postural deficits due to fatigue and it seems that difference was not between muscle groups due to central fatigue.

Wet, volatile, and dry biomarkers of exercise-induced muscle fatigue.

PubMed

Finsterer, Josef; Drory, Vivian E

2016-01-21

The physiological background of exercise-induced muscle fatigue(EIMUF) is only poorly understood. Thus, monitoring of EIMUF by a single or multiple biomarkers(BMs) is under debate. After a systematic literature review 91 papers were included. EIMUF is mainly due to depletion of substrates, increased oxidative stress, muscle membrane depolarisation following potassium depletion, muscle hyperthermia, muscle damage, impaired oxygen supply to the muscle, activation of an inflammatory response, or impaired calcium-handling. Dehydration, hyperammonemia, mitochondrial biogenesis, and genetic responses are also discussed. Since EIMUF is dependent on age, sex, degree of fatigue, type, intensity, and duration of exercise, energy supply during exercise, climate, training status (physical fitness), and health status, BMs currently available for monitoring EIMUF have limited reliability. Generally, wet, volatile, and dry BMs are differentiated. Among dry BMs of EIMUF the most promising include power output measures, electrophysiological measures, cardiologic measures, and questionnaires. Among wet BMs of EIMUF those most applicable include markers of ATP-metabolism, of oxidative stress, muscle damage, and inflammation. VO2-kinetics are used as a volatile BM. Though the physiology of EIMUF remains to be fully elucidated, some promising BMs have been recently introduced, which together with other BMs, could be useful in monitoring EIMUF. The combination of biomarkers seems to be more efficient than a single biomarker to monitor EIMUF. However, it is essential that efficacy, reliability, and applicability of each BM candidate is validated in appropriate studies.

Sex Comparison of Knee Extensor Size, Strength and Fatigue Adaptation to Sprint Interval Training.

PubMed

Bagley, Liam; Al-Shanti, Nasser; Bradburn, Steven; Baig, Osamah; Slevin, Mark; McPhee, Jamie S

2018-03-12

Regular sprint interval training (SIT) improves whole-body aerobic capacity and muscle oxidative potential, but very little is known about knee extensor anabolic or fatigue resistance adaptations, or whether effects are similar for males and females. The purpose of this study was to compare sex-related differences in knee extensor size, torque-velocity relationship and fatigability adaptations to 12 weeks SIT. Sixteen males and fifteen females (mean (SEM) age: 41 (±2.5) yrs) completed measurements of total body composition assessed by DXA, quadriceps muscle cross-sectional area (CSAQ) assessed by MRI, the knee extensor torque-velocity relationship (covering 0 - 240°·sec) and fatigue resistance, which was measured as the decline in torque from the first to the last of 60 repeated concentric knee extensions performed at 180°·sec. SIT consisted of 4 x 20 second sprints on a cycle ergometer set at an initial power output of 175% of power at VO2max, three times per week for 12 weeks. CSAQ increased by 5% (p=0.023) and fatigue resistance improved 4.8% (p=0.048), with no sex differences in these adaptations (sex comparisons: p=0.140 and p=0.282, respectively). Knee extensor isometric and concentric torque was unaffected by SIT in both males and females (p>0.05 for all velocities). 12 weeks SIT, totalling 4 minutes very intense cycling per week, significantly increased fatigue resistance and CSAQ similarly in males and females, but did not significantly increase torque in males or females. These results suggest that SIT is a time-effective training modality for males and females to increase leg muscle size and fatigue resistance.

Comparison of algorithms to quantify muscle fatigue in upper limb muscles based on sEMG signals.

PubMed

Kahl, Lorenz; Hofmann, Ulrich G

2016-11-01

This work compared the performance of six different fatigue detection algorithms quantifying muscle fatigue based on electromyographic signals. Surface electromyography (sEMG) was obtained by an experiment from upper arm contractions at three different load levels from twelve volunteers. Fatigue detection algorithms mean frequency (MNF), spectral moments ratio (SMR), the wavelet method WIRM1551, sample entropy (SampEn), fuzzy approximate entropy (fApEn) and recurrence quantification analysis (RQA%DET) were calculated. The resulting fatigue signals were compared considering the disturbances incorporated in fatiguing situations as well as according to the possibility to differentiate the load levels based on the fatigue signals. Furthermore we investigated the influence of the electrode locations on the fatigue detection quality and whether an optimized channel set is reasonable. The results of the MNF, SMR, WIRM1551 and fApEn algorithms fell close together. Due to the small amount of subjects in this study significant differences could not be found. In terms of disturbances the SMR algorithm showed a slight tendency to out-perform the others. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.

Androgen signaling in myocytes contributes to the maintenance of muscle mass and fiber type regulation but not to muscle strength or fatigue.

PubMed

Ophoff, Jill; Van Proeyen, Karen; Callewaert, Filip; De Gendt, Karel; De Bock, Katrien; Vanden Bosch, An; Verhoeven, Guido; Hespel, Peter; Vanderschueren, Dirk

2009-08-01

Muscle frailty is considered a major cause of disability in the elderly and chronically ill. However, the exact role of androgen receptor (AR) signaling in muscle remains unclear. Therefore, a postmitotic myocyte-specific AR knockout (mARKO) mouse model was created and investigated together with a mouse model with ubiquitous AR deletion. Muscles from mARKO mice displayed a marked reduction in AR protein (60-88%). Interestingly, body weights and lean body mass were lower in mARKO vs. control mice (-8%). The weight of the highly androgen-sensitive musculus levator ani was significantly reduced (-46%), whereas the weights of other peripheral skeletal muscles were not or only slightly reduced. mARKO mice had lower intra-abdominal fat but did not demonstrate a cortical or trabecular bone phenotype, indicating that selective ablation of the AR in myocytes affected male body composition but not skeletal homeostasis. Furthermore, muscle contractile performance in mARKO mice did not differ from their controls. Myocyte-specific AR ablation resulted in a conversion of fast toward slow fibers, without affecting muscle strength or fatigue. Similar results were obtained in ubiquitous AR deletion, showing lower body weight, whereas some but not all muscle weights were reduced. The percent slow fibers was increased, but no changes in muscle strength or fatigue could be detected. Together, our findings show that myocyte AR signaling contributes to the maintenance of muscle mass and fiber type regulation but not to muscle strength or fatigue. The levator ani weight remains the most sensitive and specific marker of AR-mediated anabolic action on muscle.

Fatigue Responses in Various Muscle Groups in Well-Trained Competitive Male Players after a Simulated Soccer Game

PubMed Central

Fransson, Dan; Vigh-Larsen, Jeppe Foged; Fatouros, Ioannis G.; Krustrup, Peter; Mohr, Magni

2018-01-01

Abstract We examined the degree of post-game fatigue and the recovery pattern in various leg and upper-body muscle groups after a simulated soccer game. Well-trained competitive male soccer players (n = 12) participated in the study. The players completed the Copenhagen Soccer Test, a 2 x 45 min simulated soccer protocol, following baseline measures of maximal voluntary contractions of multiple muscle groups and systemic markers of muscle damage and inflammation at 0, 24 and 48 h into recovery. All muscle groups had a strength decrement (p ≤ 0.05) at 0 h post-match with knee flexors (14 ± 3%) and hip abductors (6 ± 1%) demonstrating the largest and smallest impairment. However, 24 h into recovery all individual muscles had recovered. When pooled in specific muscle groups, the trunk muscles and knee joint muscles presented the largest decline 0 h post-match, 11 ± 2% for both, with the performance decrement still persistent (4 ± 1%, p ≤ 0.05) for trunk muscles 24 h into recovery. Large inter-player variations were observed in game-induced fatigue and recovery patterns in the various muscle groups. Markers of muscle damage and inflammation peaked 0 h post-match (myoglobin) and 24 h into recovery (creatine kinase), respectively, but thereafter returned to baseline. Intermittent test performance correlated with creatine kinase activity 24 h after the Copenhagen Soccer Test (r = -0.70; p = 0.02). In conclusion, post-game fatigue is evident in multiple muscle groups with knee flexors showing the greatest performance decrement. Fatigue and recovery patterns vary markedly between muscle groups and players, yet trunk muscles display the slowest recovery. PMID:29599862

Fatigue Responses in Various Muscle Groups in Well-Trained Competitive Male Players after a Simulated Soccer Game.

PubMed

Fransson, Dan; Vigh-Larsen, Jeppe Foged; Fatouros, Ioannis G; Krustrup, Peter; Mohr, Magni

2018-03-01

We examined the degree of post-game fatigue and the recovery pattern in various leg and upper-body muscle groups after a simulated soccer game. Well-trained competitive male soccer players (n = 12) participated in the study. The players completed the Copenhagen Soccer Test, a 2 x 45 min simulated soccer protocol, following baseline measures of maximal voluntary contractions of multiple muscle groups and systemic markers of muscle damage and inflammation at 0, 24 and 48 h into recovery. All muscle groups had a strength decrement ( p ≤ 0.05) at 0 h post-match with knee flexors (14 ± 3%) and hip abductors (6 ± 1%) demonstrating the largest and smallest impairment. However, 24 h into recovery all individual muscles had recovered. When pooled in specific muscle groups, the trunk muscles and knee joint muscles presented the largest decline 0 h post-match, 11 ± 2% for both, with the performance decrement still persistent (4 ± 1%, p ≤ 0.05) for trunk muscles 24 h into recovery. Large inter-player variations were observed in game-induced fatigue and recovery patterns in the various muscle groups. Markers of muscle damage and inflammation peaked 0 h post-match (myoglobin) and 24 h into recovery (creatine kinase), respectively, but thereafter returned to baseline. Intermittent test performance correlated with creatine kinase activity 24 h after the Copenhagen Soccer Test (r = -0.70; p = 0.02). In conclusion, post-game fatigue is evident in multiple muscle groups with knee flexors showing the greatest performance decrement. Fatigue and recovery patterns vary markedly between muscle groups and players, yet trunk muscles display the slowest recovery.

Relative Distribution of Quadriceps Head Anatomical Cross-Sectional Areas and Volumes – Sensitivity to Pain and to Training Intervention

PubMed Central

Sattler, M; Dannhauer, T; Ring-Dimitriou, S; Sänger, AM; Wirth, W; Hudelmaier, M; Eckstein, F

2014-01-01

SUMMARY Introduction Quadriceps heads are important in biomechanical stabilization and in the pathogenesis osteoarthritis of the knee. This is the first study to explore the relative distribution of quadriceps head anatomical cross-sectional areas (ACSA) and volumes, and their response to pain and to training intervention. Methods The relative proportions of quadriceps heads were determined in 48 Osteoarthritis Initiative participants with unilateral pain (65% women; age 45–78y). Quadriceps head volumes were also measured in 35 untrained women (45–55y) before and after 12 week training intervention. Cross-sectional areas of the vastus medialis (VM), inter-medius (VIM), and lateralis (VL), and of the rectus femoris (RF) were determined from axial T1-weighted MR images. Results The proportion of the VM on the total quadriceps ACSA increased from proximal to distal. The difference in quadriceps ACSA of painful (vs. pain-free) limbs was −5.4% for the VM (p<0.001), −6.8% for the VL (p<0.01), −2.8% for the VIM (p=0.06), and +3.4% for the RF (p=0.67) but the VM/VL ratio was not significantly altered. The muscle volume increase during training intervention was +4.2% (p<0.05) for VM, +1.3% for VL, +2.0% for VIM (p<0.05) and +1.6% for RF. Conclusion The proportion of quadriceps head relative to total muscle ACSA and volume depends on the anatomical level studied. The results suggest that there may be a differential response of the quadriceps heads to pain-induced atrophy and to training-related hypertrophy. Studies in larger samples are needed to ascertain whether the observed differences in response to pain and training are statistically and clinically significant. PMID:25153247

Effects of Static and Dynamic Stretching on the Isokinetic Peak Torques and Electromyographic Activities of the Antagonist Muscles.

PubMed

Serefoglu, Abdullah; Sekir, Ufuk; Gür, Hakan; Akova, Bedrettin

2017-03-01

The aim of this study was to investigate if static and dynamic stretching exercises of the knee muscles (quadriceps and hamstring muscles) have any effects on concentric and eccentric isokinetic peak torques and electromyographic amplitudes (EMG) of the antagonist muscles. Twenty healthy male athletes (age between 18-30 years) voluntarily participated in this study. All of the subjects visited the laboratory to complete the following intervention in a randomized order on 5 separate days; (a) non-stretching (control), (b) static stretching of the quadriceps muscles, (c) static stretching of the hamstring muscles, (d) dynamic stretching of the quadriceps muscles, and (e) dynamic stretching of the hamstring muscles. Static stretching exercises either for the quadriceps or the hamstring muscles were carried out at the standing and sitting positions. Subjects performed four successive repetitions of each stretching exercises for 30 seconds in both stretching positions. Similar to static stretching exercises two different stretching modes were designed for dynamic stretching exercises. Concentric and eccentric isokinetic peak torque for the non-stretched antagonist quadriceps or hamstring muscles at angular velocities of 60°/sec and 240°/sec and their concurrent electromyographic (EMG) activities were measured before and immediately after the intervention. Isokinetic peak torques of the non-stretched agonist hamstring and quadriceps muscles did not represent any significant (p > 0.05) differences following static and dynamic stretching of the antagonist quadriceps and hamstring muscles, respectively. Similarly, the EMG activities of the agonist muscles exhibited no significant alterations (p > 0.05) following both stretching exercises of the antagonist muscles. According to the results of the present study it is possible to state that antagonist stretching exercises either in the static or dynamic modes do not affect the isokinetic peak torques and the EMG activities