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Sample records for isometric exercise effects

  1. The effectiveness of isometric exercises as compared to general exercises in the management of chronic non-specific neck pain.

    PubMed

    Khan, Muhammad; Soomro, Rabail Rani; Ali, Syed Shahzad

    2014-09-01

    To evaluate the effectiveness of isometric exercises as compared to general exercises in chronic non-specific neck pain. For this randomised controlled trial total 68 patients (34 each group) with chronic non-specific neck pain were recruited from Alain Poly Clinic and Institute of Physical Medicine & Rehabilitation Dow University of Health Sciences, Karachi between May, 2012 and August, 2012. Simple randomisation method was used to assign participants into isometric exercise group and general exercise groups. The isometric exercise group performed exercises for neck muscle groups with a rubber band and general exercises group performed active range of movement exercises for all neck movements. Patients in both groups received 3 supervised treatment sessions per week for 12 weeks. Visual Analogue Scale (VAS), North wick Park Neck Pain Questionnaire and goniometer were used to assess pain, disability and neck range of movements at baseline and after 12 weeks. Both interventions showed statistically significant improvements in pain, function and range of movement p = 0.001f or isometric exercise group, p = 0.04 for general exercises group and p = 0.001 for range of movement. However, mean improvements in post intervention VAS score and North wick Park Neck Pain Questionnaire score was better in isometric exercises group as compared to general exercise group. In conclusion, both interventions are effective in the treatment of chronic non-specific neck pain however; isometric exercises are clinically more effective than general exercises.

  2. Isometric exercise: cardiovascular responses in normal and cardiac populations.

    PubMed

    Hanson, P; Nagle, F

    1987-05-01

    Isometric exercise produces a characteristic pressor increase in blood pressure which may be important in maintaining perfusion of muscle during sustained contraction. This response is mediated by combined central and peripheral afferent input to medullary cardiovascular centers. In normal individuals the increase in blood pressure is mediated by a rise in cardiac output with little or no change in systemic vascular resistance. However, the pressor response is also maintained during pharmacologic blockade or surgical denervation by increasing systemic vascular resistance. Left ventricular function is normally maintained or improves in normal subjects and cardiac patients with mild impairment of left ventricular contractility. Patients with poor left ventricular function may show deterioration during isometric exercise, although this pattern of response is difficult to predict from resting studies. Recent studies have shown that patients with uncomplicated myocardial infarction can perform submaximum isometric exercise such as carrying weights in the range of 30 to 50 lb without difficulty or adverse responses. In addition, many patients who show ischemic ST depression or angina during dynamic exercise may have a reduced ischemic response during isometric or combined isometric and dynamic exercise. Isometric exercises are frequently encountered in activities of daily living and many occupational tasks. Cardiac patients should be gradually exposed to submaximum isometric training in supervised cardiac rehabilitation programs. Specific job tasks that require isometric or combined isometric and dynamic activities may be evaluated by work simulation studies. This approach to cardiac rehabilitation may facilitate patients who wish to return to a job requiring frequent isometric muscle contraction. Finally, there is a need for additional research on the long-term effects of isometric exercise training on left ventricular hypertrophy and performance. The vigorous training

  3. Isometric exercise (image)

    MedlinePlus

    Isometric exercise works muscles and strengthens bone. Increased muscle mass elevates metabolism, which in turn burns fat. Strength training is also called anaerobic exercise, as opposed to aerobic, because increased oxygen production is not ...

  4. Brief submaximal isometric exercise improves cold pressor pain tolerance.

    PubMed

    Foxen-Craft, Emily; Dahlquist, Lynnda M

    2017-10-01

    Exercise-induced hypoalgesia (EIH), or the inhibition of pain following physical exercise, has been demonstrated in adults, but its mechanisms have remained unclear due to variations in methodology. This study aimed to address methodological imitations of past studies and contribute to the literature demonstrating the generalizability of EIH to brief submaximal isometric exercise and cold pressor pain. Young adults (n = 134) completed a baseline cold pressor trial, maximal voluntary contraction (hand grip strength) assessment, 10-min rest, and either a 2-min submaximal isometric handgrip exercise or a sham exercise in which no force was exerted, followed by a cold pressor posttest. Results indicated that cold pressor pain tolerance significantly increased during the exercise condition, but not during the sham exercise condition. Exercise did not affect pain intensity and marginally affected pain unpleasantness ratings. These findings suggest that submaximal isometric exercise can improve cold pressor pain tolerance but may have an inconsistent analgesic effect on ratings of cold pressor pain.

  5. Effects of isotonic and isometric exercises with mist sauna bathing on cardiovascular, thermoregulatory, and metabolic functions

    NASA Astrophysics Data System (ADS)

    Iwase, Satoshi; Kawahara, Yuko; Nishimura, Naoki; Nishimura, Rumiko; Sugenoya, Junichi; Miwa, Chihiro; Takada, Masumi

    2014-08-01

    To clarify the effects of isometric and isotonic exercise during mist sauna bathing on the cardiovascular function, thermoregulatory function, and metabolism, six healthy young men (22 ± 1 years old, height 173 ± 4 cm, weight 65.0 ± 5.0 kg) were exposed to a mist sauna for 10 min at a temperature of 40 °C, and relative humidity of 100 % while performing or not performing ˜30 W of isometric or isotonic exercise. The effect of the exercise was assessed by measuring tympanic temperature, heart rate, systolic and diastolic blood pressure, chest sweat rate, chest skin blood flow, and plasma catecholamine and cortisol, glucose, lactate, and free fatty acid levels. Repeated measures ANOVA showed no significant differences in blood pressure, skin blood flow, sweat rate, and total amount of sweating. Tympanic temperature increased more during isotonic exercise, and heart rate increase was more marked during isotonic exercise. The changes in lactate indicated that fatigue was not very great during isometric exercise. The glucose level indicated greater energy expenditure during isometric exercise. The free fatty acid and catecholamine levels indicated that isometric exercise did not result in very great energy expenditure and stress, respectively. The results for isotonic exercise of a decrease in lactate level and an increase in plasma free fatty acid level indicated that fatigue and energy expenditure were rather large while the perceived stress was comparatively low. We concluded that isotonic exercise may be a more desirable form of exercise during mist sauna bathing given the changes in glucose and free fatty acid levels.

  6. Effect of nifedipine on choroidal blood flow regulation during isometric exercise.

    PubMed

    Schmidl, Doreen; Prinz, Ana; Kolodjaschna, Julia; Polska, Elzbieta; Luksch, Alexandra; Fuchsjager-Mayrl, Gabriele; Garhofer, Gerhard; Schmetterer, Leopold

    2012-01-25

    To determine whether nifedipine, an L-type calcium channel blocker, alters choroidal blood flow (ChBF) regulation during isometric exercise in healthy subjects. The study was carried out in a randomized, placebo-controlled, double-masked, two-way crossover design. Fifteen healthy male subjects were randomly assigned to receive either placebo or nifedipine on two different study days. Subfoveal ChBF was measured with laser Doppler flowmetry while the study participants performed isometric exercise (squatting). This was performed before drug administration and during infusion of nifedipine and placebo, respectively. Mean arterial pressure (MAP) and intraocular pressure (IOP) were measured noninvasively, and ocular perfusion pressure (OPP) was calculated as ⅔ MAP-IOP. MAP and OPP increased significantly during all squatting periods (P < 0.01). The increase in ChBF was less pronounced than the increase in OPP during isometric exercise. Nifedipine did not alter the OPP increase in response to isometric exercise, but it significantly augmented the exercise-induced increase in ChBF (P < 0.001 vs. placebo). Although ChBF increased by a maximum of 14.2% ± 9.2% during the squatting period when placebo was administered, the maximum increase during administration of nifedipine was 23.2% ± 7.2%. In conclusion, the data of the present study suggest that nifedipine augments the ChBF response to an experimental increase in OPP. In addition, it confirms that the choroidal vasculature has a significant regulatory capacity over wide ranges of OPPs during isometric exercise. (ClinicalTrials.gov number, NCT00280462.).

  7. Systemic Exercise-Induced Hypoalgesia Following Isometric Exercise Reduces Conditioned Pain Modulation.

    PubMed

    Alsouhibani, Ali; Vaegter, Henrik Bjarke; Hoeger Bement, Marie

    2018-04-03

    Physically active individuals show greater conditioned pain modulation (CPM) compared with less active individuals. Understanding the effects of acute exercise on CPM may allow for a more targeted use of exercise in the management of pain. This study investigated the effects of acute isometric exercise on CPM. In addition, the between-session and within-session reliability of CPM was investigated. Experimental, randomized crossover study. Laboratory at Marquette University. Thirty healthy adults (19.3±1.5 years, 15 males). Subjects underwent CPM testing before and after isometric exercise (knee extension, 30% maximum voluntary contraction for three minutes) and quiet rest in two separate experimental sessions. Pressure pain thresholds (PPTs) at the quadriceps and upper trapezius muscles were assessed before, during, and after ice water immersions. PPTs increased during ice water immersion (i.e., CPM), and quadriceps PPT increased after exercise (P < 0.05). CPM decreased similarly following exercise and quiet rest (P > 0.05). CPM within-session reliability was fair to good (intraclass correlation coefficient [ICC] = 0.43-0.70), and the between-session reliability was poor (ICC = 0.20-0.35). Due to the variability in the systemic exercise-induced hypoalgesia (EIH) response, participants were divided into systemic EIH responders (N = 9) and nonresponders (N = 21). EIH responders experienced attenuated CPM following exercise (P = 0.03), whereas the nonresponders showed no significant change (P > 0.05). Isometric exercise decreased CPM in individuals who reported systemic EIH, suggesting activation of shared mechanisms between CPM and systemic EIH responses. These results may improve the understanding of increased pain after exercise in patients with chronic pain and potentially attenuated CPM.

  8. 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.

  9. Reduced Modulation of Pain in Older Adults After Isometric and Aerobic Exercise.

    PubMed

    Naugle, Kelly M; Naugle, Keith E; Riley, Joseph L

    2016-06-01

    Laboratory-based studies show that acute aerobic and isometric exercise reduces sensitivity to painful stimuli in young healthy individuals, indicative of a hypoalgesic response. However, little is known regarding the effect of aging on exercise-induced hypoalgesia (EIH). The purpose of this study was to examine age differences in EIH after submaximal isometric exercise and moderate and vigorous aerobic exercise. Healthy older and younger adults completed 1 training session and 4 testing sessions consisting of a submaximal isometric handgrip exercise, vigorous or moderate intensity stationary cycling, or quiet rest (control). The following measures were taken before and after exercise/quiet rest: 1) pressure pain thresholds, 2) suprathreshold pressure pain ratings, 3) pain ratings during 30 seconds of prolonged noxious heat stimulation, and 4) temporal summation of heat pain. The results revealed age differences in EIH after isometric and aerobic exercise, with younger adults experiencing greater EIH compared with older adults. The age differences in EIH varied across pain induction techniques and exercise type. These results provide evidence for abnormal pain modulation after acute exercise in older adults. This article enhances our understanding of the influence of a single bout of exercise on pain sensitivity and perception in healthy older compared with younger adults. This knowledge could help clinicians optimize exercise as a method of pain management. Copyright © 2016 American Pain Society. Published by Elsevier Inc. All rights reserved.

  10. Differential activation of parts of the latissimus dorsi with various isometric shoulder exercises.

    PubMed

    Park, Se-yeon; Yoo, Won-gyu

    2014-04-01

    As no study has examined whether the branches of the latissimus dorsi are activated differently in different exercises, we investigated intramuscular differences of components of the latissimus dorsi during various shoulder isometric exercises. Seventeen male subjects performed four isometric exercises: shoulder extension, adduction, internal rotation, and shoulder depression. Surface electromyography (sEMG) was used to collect data from the medial and lateral components of the latissimus dorsi during the isometric exercises. Two-way repeated analysis of variance with two within-subject factors (exercise condition and muscle branch) was used to determine the significance of differences between the branches, and which branch was activated more with the exercise variation. The root mean squared sEMG values for the muscles were normalized using the modified isolation equation (%Isolation) and maximum voluntary isometric contraction (%MVIC). Neither the %MVIC nor %Isolation data differed significantly between muscle branches, while there was a significant difference with exercise. %MVIC was significantly higher with shoulder extension, compared to the other isometric exercises. There was a significant correlation between exercise condition and muscle branch in the %Isolation data. Shoulder extension and adduction and internal rotation increased %Isolation of the medial latissimus dorsi more than shoulder depression. Shoulder depression had the highest value of %Isolation of the lateral latissimus dorsi compared to the other isometric exercises. Comparing the medial and lateral latissimus dorsi, the medial component was predominantly activated with shoulder extension, adduction, and internal rotation, and the lateral component with shoulder depression. Shoulder extension is effective for activating the latissimus dorsi regardless of the intramuscular branch. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Comparison of EMG activity on abdominal muscles during plank exercise with unilateral and bilateral additional isometric hip adduction.

    PubMed

    Kim, Soo-Yong; Kang, Min-Hyeok; Kim, Eui-Ryong; Jung, In-Gui; Seo, Eun-Young; Oh, Jae-Seop

    2016-10-01

    The aim of this study was to investigate the effects of additional isometric hip adduction during the plank exercise on the abdominal muscles. Twenty healthy young men participated in this study. Surface electromyography (EMG) was used to monitor the activity of the bilateral rectus abdominis (RA), the internal oblique (IO), and the external oblique (EO) muscles. The participants performed three types of plank exercise; the standard plank exercise, the plank exercise with bilateral isometric hip adduction, and the plank exercise with unilateral isometric hip adduction. All abdominal muscle activity was significantly increased during the plank exercise combined with the bilateral and unilateral isometric hip adduction compared with the standard plank exercise (p<0.05). Bilateral IO, EO, and left RA muscle activity was significantly increased during the unilateral isometric hip adduction compared with the bilateral isometric hip adduction (p<0.05). These findings suggest that additional isometric hip adduction during the plank exercise could be a useful method to enhance abdominal muscle activity. In particular, the unilateral isometric hip adduction is a more beneficial exercise than the bilateral isometric hip adduction. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. A new isometric quadriceps-strengthening exercise using EMG-biofeedback.

    PubMed

    Kesemenli, Cumhur C; Sarman, Hakan; Baran, Tuncay; Memisoglu, Kaya; Binbir, Ismail; Savas, Yilmaz; Isik, Cengiz; Boyraz, Ismail; Koc, Bunyamin

    2014-01-01

    A new isometric contraction quadriceps-strengthening exercise was developed to restore the quadriceps strength lost after knee surgery more rapidly. This study evaluated the results of this new method. Patients were taught to perform the isometric quadriceps-strengthening exercise in the unaffected knee in the supine position, and then they performed it in the affected knee. First, patients were taught the classical isometric quadriceps-strengthening exercise, and then they were taught our new alternative method: "pull the patella superiorly tightly and hold the leg in the same position for 10 seconds". Afterward, the quadriceps contraction was evaluated using a non-invasive Myomed 932 EMG-biofeedback device (Enraf-Nonius, The Netherlands) with gel-containing 48 mm electrodes (Türklab, The Turkey) placed on both knees. The isometric quadriceps-strengthening exercise performed using our new method had stronger contraction than the classical method (P < 0.01). The new method involving pulling the patella superiorly appears to be a better choice, which can be applied easily, leading to better patient compliance and greater quadriceps force after arthroscopic and other knee surgeries.

  13. Comparative effects of proprioceptive and isometric exercises on pain intensity and difficulty in patients with knee osteoarthritis: A randomised control study.

    PubMed

    Ojoawo, Adesola O; Olaogun, Matthew O B; Hassan, Mariam A

    2016-11-14

    The study compared the effects of isometric quadriceps exercise and proprioceptive exercise on pain, joint stiffness and physical difficulties of patients with knee osteoarthritis. Forty-five patients with history of knee osteoarthritis were randomly allocated into two groups; A with 23 subjects and B with 22 subjects. All subjects received infrared radiation for 20 minutes and kneading massage with methyl salicylate ointment. Group A underwent proprioceptive exercises while Group B had isometric quadriceps exercise. Each exercise session lasted for 10 minutes according to standard protocol, twice in a week for six weeks. Pre-treatment, 3rd week and 6th week pain intensity, joint stiffness and physical difficulties were assessed using Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) questionnaire. Statistical package for social sciences (SPSS) version 17 was used to analyse the data while descriptive and inferential statistics were used to summarise the result. Proprioceptive exercises reduced pain intensity significantly (F = 4.76; p = 0.00) at 6th week with effect size of 2.79, and physical difficulty (F = 3.69; p < 0.04) with effect size of 7.53 better than isometric exercises. There was a significant reduction in the pain intensity (F = 12.08; p < 0.001), and physical difficulties (F = 3.69, p = 0.04) in pre-treatment, 3rd week and 6th week in both Group A and B. Both exercises are effective but proprioceptive exercises may be more effective in the management of patients with knee osteoarthritis (KOA) than isometric exercises.

  14. Comparison of isometric exercises for activating latissimus dorsi against the upper body weight.

    PubMed

    Park, Se-yeon; Yoo, Won-gyu; An, Duk-hyun; Oh, Jae-seop; Lee, Jung-hoon; Choi, Bo-ram

    2015-02-01

    Because there is little agreement as to which exercise is the most effective for activating the latissimus dorsi, and its intramuscular components are rarely compared, we investigated the intramuscular components of the latissimus dorsi during both trunk and shoulder exercises. Sixteen male subjects performed four isometric exercises: inverted row, body lifting, trunk extension, and trunk lateral bending. Surface electromyography (sEMG) was used to collect data from the medial and lateral components of the latissimus dorsi, lower trapezius, and the erector spinae at the 12th thoracic level during the isometric exercises. Two-way repeated analysis of variance with two within-subject factors (muscles and exercise conditions) was used to determine the significance of differences between the muscles and differences between exercise variations. The inverted row showed the highest values for the medial latissimus dorsi, which were significantly higher than those of the body lifting or trunk extension exercises. For the lateral latissimus dorsi, lateral bending showed significantly higher muscle activity than the inverted row or trunk extension. During body lifting, the % maximum voluntary isometric contraction (MVIC) of the erector spinae showed the lowest value, significantly lower than those of the other isometric exercises. The inverted row exercise was effective for activating the medial latissimus dorsi versus the shoulder depression and trunk exertion exercises. The lateral bending and body lifting exercises were favorable for activating the lateral component of the latissimus dorsi. Evaluating trunk lateral bending is essential for examining the function of the latissimus dorsi. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Effect of gender on strength gains after isometric exercise coupled with electromyographic biofeedback in knee osteoarthritis: a preliminary study.

    PubMed

    Anwer, S; Equebal, A; Nezamuddin, M; Kumar, R; Lenka, P K

    2013-09-01

    The objective of this trial was to evaluate the effect of gender on strength gains after five week training programme that consisted of isometric exercise coupled with electromyographic biofeedback to the quadriceps muscle. Forty-three (20 men and 23 women) patients with knee osteoarthritis (OA), were placed into two groups based on their gender. Both groups performed isometric exercise coupled with electromyographic biofeedback for five days a week for five weeks. Both groups reported gains in muscle strength after five week training. However, the difference was found to be statistically insignificant between the two groups (P=0.224). The results suggest that gender did not affect gains in muscle strength by isometric exercise coupled with electromyographic biofeedback in patients with knee OA. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

  16. Comparison of the Effect of Massage Therapy and Isometric Exercises on Primary Dysmenorrhea: A Randomized Controlled Clinical Trial.

    PubMed

    Azima, Sara; Bakhshayesh, Hajar Rajaei; Kaviani, Maasumeh; Abbasnia, Keramatallah; Sayadi, Mehrab

    2015-12-01

    Dysmenorrhea is the most common cyclic pelvic pain, and it affects the quality of life of many women. We sought to compare the effects of massage and isometric exercises on primary dysmenorrhea. We conducted a randomized controlled trial at the dormitories of Shiraz University among 102 students with primary dysmenorrheal. The student groups were randomly divided into massage, isometric exercises, and control groups. The first group received 2 consecutive cycles of effleurage massage with lavender oil. The second group had 8 weeks of isometric exercises. No intervention was performed for the control group. Pain intensity was measured and recorded by using a visual analog scale. In addition, the duration of pain was measured in hours, and Spielberger's questionnaire was used to measure the anxiety level. Pain intensity had significantly reduced in the massage and exercises groups; the reduction was more significant in the massage group (P < .001). The results revealed a significant difference among the 3 groups in regard to the mean duration of pain after the third cycle (P = .006). However, no significant difference was found among the 3 groups concerning the mean level of anxiety. The results of intragroup comparisons only showed a significant reduction of anxiety level in the massage group after the third cycle (P = .017). Based on the present findings, it seems that massage therapy and isometric exercises were effective in reducing some symptoms of dysmenorrhea. Copyright © 2015 North American Society for Pediatric and Adolescent Gynecology. Published by Elsevier Inc. All rights reserved.

  17. 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.

  18. Do isometric pull-down exercises increase the acromio-humeral distance?

    PubMed

    Sealey, P; Critchley, D

    2017-06-01

    To evaluate the effect of isometric shoulder extension in 90° shoulder flexion on the acromio-humeral distance, to establish the force required to achieve a clinically important increase in the acromio-humeral distance, and to investigate the practicality and reliability of real-time ultrasound measurement of the acromio-humeral distance in 90° shoulder forward flexion. Prospective single-group intervention. King's College London, Guy's Campus. Twenty healthy volunteers [five males and 15 females (40 shoulders)] with a mean age of 32 (standard deviation 10, range 19 to 55) years were recruited from the faculty and staff at King's College London. The acromio-humeral distance in asymptomatic participants was measured using real-time ultrasound in the neutral position at rest, at 90° shoulder flexion at rest, and while performing an isometric pull-down exercise at 100%, 50%, 30% and 10% maximal voluntary isometric contraction. Real-time ultrasound measures of the acromio-humeral distance. Of the 20 participants, 38 shoulders were imaged. In 90° shoulder flexion, pull-down exercises at all levels of force increased the acromio-humeral distance compared with no pull-down (P<0.05), but this was only clinically significant in males. Measures had excellent short-term intra-operator reliability. Isometric pull-down exercises lead to an increase in the acromio-humeral distance in asymptomatic males that may be clinically important, and therefore may be an appropriate exercise for patients with shoulder pathology. Ultrasound measurement of the acromio-humeral distance in 90° shoulder flexion is practical and reliable. Copyright © 2016 Chartered Society of Physiotherapy. Published by Elsevier Ltd. All rights reserved.

  19. Effects of a 16-week Pilates exercises training program for isometric trunk extension and flexion strength.

    PubMed

    Kliziene, Irina; Sipaviciene, Saule; Vilkiene, Jovita; Astrauskiene, Audrone; Cibulskas, Gintautas; Klizas, Sarunas; Cizauskas, Ginas

    2017-01-01

    To evaluate the effects of Pilates exercises designed to improve isometric trunk extension and flexion strength of muscles in women with chronic low back pain (cLBP). Female volunteers with cLBP were divided into an experimental group (EG; n = 27) and a control group (CG; n = 27). Pilates exercises were performed twice per week by the EG; the duration of each session was 60 min. The program lasted for 16 weeks; thus patients underwent a total of 32 exercise sessions. The maximum isometric waist bending strength of the EG had improved significantly (p = 0.001) after 16 weeks of the Pilates program. The results of trunk flexion muscle endurance tests significantly depended on the trunk extension muscle endurance before the intervention, and at 1 month (r = 0.723, p < 0.001) and 2 months (r = 0.779, p < 0.001) after the Pilates exercise program. At the end of the 16-week exercise program, cLBP intensity decreased by 2.01 ± 0.8 (p < 0.05) in the EG, and this reduction persisted for 1 month after completion of the program. At 1 and 2 months after cessation of the Pilates exercise program the pain intensified and the functional state deteriorated much faster than the maximum trunk muscle strength. Therefore, it can be concluded that, to decrease pain and improve functional condition, regular exercise (and not only improved strength and endurance) is required. We established that, although the 16-week lumbar stabilization exercise program increased isometric trunk extension and flexion strength and this increase in strength persisted for 2 months, decreased LBP and improved functional condition endured for only 1 month. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Exercise-Induced Hypoalgesia After Isometric Wall Squat Exercise: A Test-Retest Reliabilty Study.

    PubMed

    Vaegter, Henrik Bjarke; Lyng, Kristian Damgaard; Yttereng, Fredrik Wannebo; Christensen, Mads Holst; Sørensen, Mathias Brandhøj; Graven-Nielsen, Thomas

    2018-05-19

    Isometric exercises decrease pressure pain sensitivity in exercising and nonexercising muscles known as exercise-induced hypoalgesia (EIH). No studies have assessed the test-retest reliability of EIH after isometric exercise. This study investigated the EIH on pressure pain thresholds (PPTs) after an isometric wall squat exercise. The relative and absolute test-retest reliability of the PPT as a test stimulus and the EIH response in exercising and nonexercising muscles were calculated. In two identical sessions, PPTs of the thigh and shoulder were assessed before and after three minutes of quiet rest and three minutes of wall squat exercise, respectively, in 35 healthy subjects. The relative test-retest reliability of PPT and EIH was determined using analysis of variance models, Person's r, and intraclass correlations (ICCs). The absolute test-retest reliability of EIH was determined based on PPT standard error of measurements and Cohen's kappa for agreement between sessions. Squat increased PPTs of exercising and nonexercising muscles by 16.8% ± 16.9% and 6.7% ± 12.9%, respectively (P < 0.001), with no significant differences between sessions. PPTs within and between sessions showed moderately strong correlations (r ≥ 0.74) and excellent (ICC ≥ 0.84) within-session (rest) and between-session test-retest reliability. EIH responses of exercising and nonexercising muscles showed no systematic errors between sessions; however, the relative test-retest reliability was low (ICCs = 0.03-0.43), and agreement in EIH responders and nonresponders between sessions was not significant (κ < 0.13, P > 0.43). A wall squat exercise increased PPTs compared with quiet rest; however, the relative and absolute reliability of the EIH response was poor. Future research is warranted to investigate the reliability of EIH in clinical pain populations.

  1. The safety of isometric exercise

    PubMed Central

    Wiles, Jonathan D.; Taylor, Katrina; Coleman, Damian; Sharma, Rajan; O’Driscoll, Jamie M.

    2018-01-01

    Abstract Few studies have investigated the relative safety of prescribing isometric exercise (IE) to reduce resting blood pressure (BP). This study aimed to ascertain the safety of the hemodynamic response during an IE wall squat protocol. Twenty-six hypertensive (BP of 120–139 mm Hg systolic and/or 80–90 mm Hg diastolic) males (45 ± 8 years; 1.78 ± 0.07 m; 89.7 ± 12.3 kg; mean ± SD), visited the laboratory on 2 separate occasions. Heart rate (HR) and BP were measured at rest and continuously throughout exercise. In visit 1, participants completed a continuous incremental isometric wall squat exercise test, starting at 135° of knee flexion, decreasing by 10° every 2 minutes until 95° (final stage). Exercise was terminated upon completion of the test or volitional fatigue. The relationship between knee joint angle and mean HR was used to calculate the participant-specific knee joint angle required to elicit a target HR of 95% HRpeak. This angle was used to determine exercise intensity for a wall squat training session consisting of 4 × 2 minute bouts (visit 2). Systolic BPs during the exercise test and training were 173 ± 21 mm Hg and 171 ± 19 mm Hg, respectively, (P > .05) and were positively related (r = 0.73, P < .05) with ratio limits of agreement (LoA) of 0.995 ×/÷ 1.077. Diastolic BPs were 116 ± 14 mm Hg and 113 ± 11 mm Hg, respectively, (P > .05) and were positively related (r = 0.42, P < .05) with ratio LoA of 0.99 ×/÷ 1.107. No participant recorded a systolic BP > 250 mm Hg. Diastolic BP values > 115 mm Hg were recorded in 12 participants during the incremental test and 6 participants during the training session. Peak rate pressure product was 20681 ± 3911 mm Hg bpm during the IE test and was lower (18074 ± 3209 mm Hg bpm) during the IE session (P = .002). No adverse effects were reported. Based on the current ACSM guidelines for aerobic exercise

  2. Insulin and glucose responses during bed rest with isotonic and isometric exercise

    NASA Technical Reports Server (NTRS)

    Dolkas, C. B.; Greenleaf, J. E.

    1977-01-01

    The effects of daily intensive isotonic (68% maximum oxygen uptake) and isometric (21% maximum extension force) leg exercise on plasma insulin and glucose responses to an oral glucose tolerance test (OGTT) during 14-day bed-rest (BR) periods were investigated in seven young healthy men. The OGTT was given during ambulatory control and on day 10 of the no-exercise, isotonic, and isometric exercise BR periods during the 15-wk study. The subjects were placed on a controlled diet starting 10 days before each BR period. During BR, basal plasma glucose concentration remained unchanged with no exercise, but increased (P less 0.05) to 87-89 mg/100 ml with both exercise regimens on day 2, and then fell slightly below control levels on day 13. The fall in glucose content during BR was independent of the exercise regimen and was an adjustment for the loss of plasma volume. The intensity of the responses of insulin and glucose to the OGTT was inversely proportional to the total daily energy expenditure during BR. It was estimated that at least 1020 kcal/day must be provided by supplemental exercise to restore the hyperinsulinemia to control levels.

  3. Regular physical exercise improves cardiac autonomic and muscle vasodilatory responses to isometric exercise in healthy elderly.

    PubMed

    Sarmento, Adriana de Oliveira; Santos, Amilton da Cruz; Trombetta, Ivani Credidio; Dantas, Marciano Moacir; Oliveira Marques, Ana Cristina; do Nascimento, Leone Severino; Barbosa, Bruno Teixeira; Dos Santos, Marcelo Rodrigues; Andrade, Maria do Amparo; Jaguaribe-Lima, Anna Myrna; Brasileiro-Santos, Maria do Socorro

    2017-01-01

    The objective of this study was to evaluate cardiac autonomic control and muscle vasodilation response during isometric exercise in sedentary and physically active older adults. Twenty healthy participants, 10 sedentary and 10 physically active older adults, were evaluated and paired by gender, age, and body mass index. Sympathetic and parasympathetic cardiac activity (spectral and symbolic heart rate analysis) and muscle blood flow (venous occlusion plethysmography) were measured for 10 minutes at rest (baseline) and during 3 minutes of isometric handgrip exercise at 30% of the maximum voluntary contraction (sympathetic excitatory maneuver). Variables were analyzed at baseline and during 3 minutes of isometric exercise. Cardiac autonomic parameters were analyzed by Wilcoxon and Mann-Whitney tests. Muscle vasodilatory response was analyzed by repeated-measures analysis of variance followed by Tukey's post hoc test. Sedentary older adults had higher cardiac sympathetic activity compared to physically active older adult subjects at baseline (63.13±3.31 vs 50.45±3.55 nu, P =0.02). The variance (heart rate variability index) was increased in active older adults (1,438.64±448.90 vs 1,402.92±385.14 ms, P =0.02), and cardiac sympathetic activity (symbolic analysis) was increased in sedentary older adults (5,660.91±1,626.72 vs 4,381.35±1,852.87, P =0.03) during isometric handgrip exercise. Sedentary older adults showed higher cardiac sympathetic activity (spectral analysis) (71.29±4.40 vs 58.30±3.50 nu, P =0.03) and lower parasympathetic modulation (28.79±4.37 vs 41.77±3.47 nu, P =0.03) compared to physically active older adult subjects during isometric handgrip exercise. Regarding muscle vasodilation response, there was an increase in the skeletal muscle blood flow in the second (4.1±0.5 vs 3.7±0.4 mL/min per 100 mL, P =0.01) and third minute (4.4±0.4 vs 3.9±0.3 mL/min per 100 mL, P =0.03) of handgrip exercise in active older adults. The results indicate

  4. Regular physical exercise improves cardiac autonomic and muscle vasodilatory responses to isometric exercise in healthy elderly

    PubMed Central

    Sarmento, Adriana de Oliveira; Santos, Amilton da Cruz; Trombetta, Ivani Credidio; Dantas, Marciano Moacir; Oliveira Marques, Ana Cristina; do Nascimento, Leone Severino; Barbosa, Bruno Teixeira; Dos Santos, Marcelo Rodrigues; Andrade, Maria do Amparo; Jaguaribe-Lima, Anna Myrna; Brasileiro-Santos, Maria do Socorro

    2017-01-01

    The objective of this study was to evaluate cardiac autonomic control and muscle vasodilation response during isometric exercise in sedentary and physically active older adults. Twenty healthy participants, 10 sedentary and 10 physically active older adults, were evaluated and paired by gender, age, and body mass index. Sympathetic and parasympathetic cardiac activity (spectral and symbolic heart rate analysis) and muscle blood flow (venous occlusion plethysmography) were measured for 10 minutes at rest (baseline) and during 3 minutes of isometric handgrip exercise at 30% of the maximum voluntary contraction (sympathetic excitatory maneuver). Variables were analyzed at baseline and during 3 minutes of isometric exercise. Cardiac autonomic parameters were analyzed by Wilcoxon and Mann–Whitney tests. Muscle vasodilatory response was analyzed by repeated-measures analysis of variance followed by Tukey’s post hoc test. Sedentary older adults had higher cardiac sympathetic activity compared to physically active older adult subjects at baseline (63.13±3.31 vs 50.45±3.55 nu, P=0.02). The variance (heart rate variability index) was increased in active older adults (1,438.64±448.90 vs 1,402.92±385.14 ms, P=0.02), and cardiac sympathetic activity (symbolic analysis) was increased in sedentary older adults (5,660.91±1,626.72 vs 4,381.35±1,852.87, P=0.03) during isometric handgrip exercise. Sedentary older adults showed higher cardiac sympathetic activity (spectral analysis) (71.29±4.40 vs 58.30±3.50 nu, P=0.03) and lower parasympathetic modulation (28.79±4.37 vs 41.77±3.47 nu, P=0.03) compared to physically active older adult subjects during isometric handgrip exercise. Regarding muscle vasodilation response, there was an increase in the skeletal muscle blood flow in the second (4.1±0.5 vs 3.7±0.4 mL/min per 100 mL, P=0.01) and third minute (4.4±0.4 vs 3.9±0.3 mL/min per 100 mL, P=0.03) of handgrip exercise in active older adults. The results indicate that

  5. THE ANTIHYPERTENSIVE EFFECTS OF AEROBIC VERSUS ISOMETRIC HANDGRIP RESISTANCE EXERCISE

    PubMed Central

    ASH, Garrett I.; TAYLOR, Beth A.; THOMPSON, Paul D.; MACDONALD, Hayley V.; LAMBERTI, Lauren; CHEN, Ming-Hui; FARINATTI, Paulo; KRAEMER, William J.; PANZA, Gregory A.; ZALESKI, Amanda L.; DESHPANDE, Ved; BALLARD, Kevin D.; MUJTABA, Mohammadtokir; WHITE, C. Michael; PESCATELLO, Linda S.

    2017-01-01

    Aerobic exercise reduces blood pressure (BP) on average 5 to 7 mmHg among those with hypertension; limited evidence suggests similar or even greater BP benefits may result from isometric handgrip (IHG) resistance exercise. We conducted a randomized controlled trial investigating the antihypertensive effects of an acute bout of aerobic compared to IHG exercise in the same individuals. Middle-aged adults (n=27) with prehypertension and obesity randomly completed three experiments: aerobic [60% peak oxygen uptake, 30 minutes]; IHG [30% maximum voluntary contraction, 4x2 minutes bilateral]; and non-exercise control. Subjects were assessed for carotid-femoral pulse wave velocity (PWV) pre and post exercise, and left the laboratory wearing an ambulatory BP monitor. Systolic and diastolic BP (SBP/DBP) were lower after aerobic versus IHG (4.8±1.8/3.1±1.3mmHg, p=0.01/0.04) and control (5.6±1.8/3.6±1.3mmHg, p=0.02/0.04) over the awake hours, with no difference between IHG versus control (p=0.80/0.83). PWV changes following acute exercise did not differ by modality (aerobic increased 0.01±0.21m•s−1, IHG decreased 0.06±0.15m•s−1, control increased 0.25±0.17m•s−1, p>0.05). A subset of participants then completed either 8 weeks of aerobic or IHG training. Awake SBP was lower after versus before aerobic training (7.6±3.1mmHg, p=0.02), while sleep DBP was higher after IHG training (7.7±2.3mmHg, p=0.02). Our findings did not support IHG as antihypertensive therapy but that aerobic exercise should continue to be recommended as the primary exercise modality for its immediate and sustained BP benefits. PMID:27861249

  6. Isometric exercise induces analgesia and reduces inhibition in patellar tendinopathy.

    PubMed

    Rio, Ebonie; Kidgell, Dawson; Purdam, Craig; Gaida, Jamie; Moseley, G Lorimer; Pearce, Alan J; Cook, Jill

    2015-10-01

    Few interventions reduce patellar tendinopathy (PT) pain in the short term. Eccentric exercises are painful and have limited effectiveness during the competitive season. Isometric and isotonic muscle contractions may have an immediate effect on PT pain. This single-blinded, randomised cross-over study compared immediate and 45 min effects following a bout of isometric and isotonic muscle contractions. Outcome measures were PT pain during the single-leg decline squat (SLDS, 0-10), quadriceps strength on maximal voluntary isometric contraction (MVIC), and measures of corticospinal excitability and inhibition. Data were analysed using a split-plot in time-repeated measures analysis of variance (ANOVA). 6 volleyball players with PT participated. Condition effects were detected with greater pain relief immediately from isometric contractions: isometric contractions reduced SLDS (mean±SD) from 7.0±2.04 to 0.17±0.41, and isotonic contractions reduced SLDS (mean±SD) from 6.33±2.80 to 3.75±3.28 (p<0.001). Isometric contractions released cortical inhibition (ratio mean±SD) from 27.53%±8.30 to 54.95%±5.47, but isotonic contractions had no significant effect on inhibition (pre 30.26±3.89, post 31.92±4.67; p=0.004). Condition by time analysis showed pain reduction was sustained at 45 min postisometric but not isotonic condition (p<0.001). The mean reduction in pain scores postisometric was 6.8/10 compared with 2.6/10 postisotonic. MVIC increased significantly following the isometric condition by 18.7±7.8%, and was significantly higher than baseline (p<0.001) and isotonic condition (p<0.001), and at 45 min (p<0.001). A single resistance training bout of isometric contractions reduced tendon pain immediately for at least 45 min postintervention and increased MVIC. The reduction in pain was paralleled by a reduction in cortical inhibition, providing insight into potential mechanisms. Isometric contractions can be completed without pain for people with PT. The

  7. 'Diving reflex' in man - Its relation to isometric and dynamic exercise.

    NASA Technical Reports Server (NTRS)

    Bergman, S. A., Jr.; Campbell, J. K.; Wildenthal, K.

    1972-01-01

    To test the influence of physical activity on the diving reflex, 10 normal men held their breath with their faces immersed in 15 C water during rest, bicycle exercise, and sustained isometric handgrip contraction. At all conditions, a slight but statistically significant elevation of blood pressure and a marked decrease in heart rate occurred during each dive. During moderate bicycle exercise heart rate fell more rapidly than at rest and the final level of bradycardia approached that achieved at rest, despite the fact that predive heart rates were much higher during exercise. When diving occurred in combination with isometric exercise, bradycardia was less severe than during resting dives and final heart rates could be represented as the sum of the expected responses to each intervention alone. In all conditions apnea without face immersion caused bradycardia that was less severe than during wet dives.

  8. Triggered intravoxel incoherent motion MRI for the assessment of calf muscle perfusion during isometric intermittent exercise.

    PubMed

    Mastropietro, Alfonso; Porcelli, Simone; Cadioli, Marcello; Rasica, Letizia; Scalco, Elisa; Gerevini, Simonetta; Marzorati, Mauro; Rizzo, Giovanna

    2018-06-01

    The main aim of this paper was to propose triggered intravoxel incoherent motion (IVIM) imaging sequences for the evaluation of perfusion changes in calf muscles before, during and after isometric intermittent exercise. Twelve healthy volunteers were involved in the study. The subjects were asked to perform intermittent isometric plantar flexions inside the MRI bore. MRI of the calf muscles was performed on a 3.0 T scanner and diffusion-weighted (DW) images were obtained using eight different b values (0 to 500 s/mm 2 ). Acquisitions were performed at rest, during exercise and in the subsequent recovery phase. A motion-triggered echo-planar imaging DW sequence was implemented to avoid movement artifacts. Image quality was evaluated using the average edge strength (AES) as a quantitative metric to assess the motion artifact effect. IVIM parameters (diffusion D, perfusion fraction f and pseudo-diffusion D*) were estimated using a segmented fitting approach and evaluated in gastrocnemius and soleus muscles. No differences were observed in quality of IVIM images between resting state and triggered exercise, whereas the non-triggered images acquired during exercise had a significantly lower value of AES (reduction of more than 20%). The isometric intermittent plantar-flexion exercise induced an increase of all IVIM parameters (D by 10%; f by 90%; D* by 124%; fD* by 260%), in agreement with the increased muscle perfusion occurring during exercise. Finally, IVIM parameters reverted to the resting values within 3 min during the recovery phase. In conclusion, the IVIM approach, if properly adapted using motion-triggered sequences, seems to be a promising method to investigate muscle perfusion during isometric exercise. Copyright © 2018 John Wiley & Sons, Ltd.

  9. Choroidal hemodynamic changes during isometric exercise in patients with inactive central serous chorioretinopathy.

    PubMed

    Tittl, Michael; Maar, Noemi; Polska, Elzbieta; Weigert, Günther; Stur, Michael; Schmetterer, Leopold

    2005-12-01

    Imaging studies suggest that the choroidal vasculature may be altered in central serous chorioretinopathy. Little is known, however, about the regulation of ocular blood flow in patients with central serous chorioretinopathy (CSC). The hypothesis for the present study was that choroidal blood flow changes during an increase in ocular perfusion pressure induced by isometric exercise may be altered in CSC. An observer-masked, two-cohort study was performed in 14 nonsmoking patients with chronic-relapsing but inactive CSC and in 14 healthy nonsmoking volunteers. Both groups were matched for age and sex. Subfoveal choroidal blood flow (CBF) was assessed with laser Doppler flowmetry, and ocular perfusion pressure (OPP) was calculated from mean arterial pressure (MAP) and intraocular pressure (IOP). Changes of CBF during isometric exercise over a period of 6 minutes were measured. Whereas the increase of MAP, the pulse rate, and the OPP were comparable between the two study groups, subfoveal CBF increased significantly more in the group of patients with CSC (P < 0.001). IOP remained unchanged in both groups during isometric exercise. At an 85% increase in OPP, subfoveal CBF was approximately twice as high in the patients with CSC compared with the healthy control group. The data indicate an abnormal subfoveal CBF regulation in patients with relapsing CSC compared with age-matched, nonsmoking, healthy volunteers during isometric exercise.

  10. Bed rest attenuates sympathetic and pressor responses to isometric exercise in antigravity leg muscles in humans.

    PubMed

    Kamiya, Atsunori; Michikami, Daisaku; Shiozawa, Tomoki; Iwase, Satoshi; Hayano, Junichiro; Kawada, Toru; Sunagawa, Kenji; Mano, Tadaaki

    2004-05-01

    Although spaceflight and bed rest are known to cause muscular atrophy in the antigravity muscles of the legs, the changes in sympathetic and cardiovascular responses to exercises using the atrophied muscles remain unknown. We hypothesized that bed rest would augment sympathetic responses to isometric exercise using antigravity leg muscles in humans. Ten healthy male volunteers were subjected to 14-day 6 degrees head-down bed rest. Before and after bed rest, they performed isometric exercises using leg (plantar flexion) and forearm (handgrip) muscles, followed by 2-min postexercise muscle ischemia (PEMI) that continues to stimulate the muscle metaboreflex. These exercises were sustained to fatigue. We measured muscle sympathetic nerve activity (MSNA) in the contralateral resting leg by microneurography. In both pre- and post-bed-rest exercise tests, exercise intensities were set at 30 and 70% of the maximum voluntary force measured before bed rest. Bed rest attenuated the increase in MSNA in response to fatiguing plantar flexion by approximately 70% at both exercise intensities (both P < 0.05 vs. before bed rest) and reduced the maximal voluntary force of plantar flexion by 15%. In contrast, bed rest did not alter the increase in MSNA response to fatiguing handgrip and had no effects on the maximal voluntary force of handgrip. Although PEMI sustained MSNA activation before bed rest in all trials, bed rest entirely eliminated the PEMI-induced increase in MSNA in leg exercises but partially attenuated it in forearm exercises. These results do not support our hypothesis but indicate that bed rest causes a reduction in isometric exercise-induced sympathetic activation in (probably atrophied) antigravity leg muscles.

  11. Role of NO in choroidal blood flow regulation during isometric exercise in healthy humans.

    PubMed

    Luksch, Alexandra; Polska, Elzbieta; Imhof, Andrea; Schering, Joanne; Fuchsjäger-Mayrl, Gabriele; Wolzt, Michael; Schmetterer, Leopold

    2003-02-01

    Nitric oxide (NO) is an important regulator of basal choroidal blood flow. Animal experiments indicate that NO is also involved in choroidal blood flow regulation during changes in ocular perfusion pressure and inhibition of NO synthase (NOS) has been reported to shift choroidal pressure-flow curves to the right. The hypothesis for the study was that inhibition of NOS may influence choroidal blood flow during isometric exercise. To test this hypothesis, a randomized, double-masked, placebo-controlled, three-way crossover study was performed in 12 healthy male volunteers. Subjects received on different study days intravenous infusions of N(G)-monomethyl-L-arginine (L-NMMA), phenylephrine, or placebo. During these infusion periods, subjects were asked to squat for 6 minutes. Choroidal blood flow was assessed with laser Doppler flowmetry, and ocular perfusion pressure (OPP) was calculated from mean arterial pressure and intraocular pressure. L-NMMA and phenylephrine increased resting OPP by 10% and 13%, respectively, but only L-NMMA reduced resting choroidal blood flow (-17%, P < 0.001). The relative increase in OPP during isometric exercise was comparable with all drugs administered. Isometric exercise increased choroidal blood flow during administration of placebo and phenylephrine, but not during administration of L-NMMA (P < 0.001 vs. placebo). These data indicate that NO plays an important role in the regulation of choroidal blood flow during isometric exercise.

  12. The Impact of Chocolate Goat's and Cow's Milk on Postresistance Exercise Endocrine Responses and Isometric Mid-Thigh Pull Performance.

    PubMed

    Bellar, David; LeBlanc, Nina R; Murphy, Kellie; Moody, Kaitlyn M; Buquet, Gina

    2016-01-01

    The present investigation examined the effects of chocolate cow's and goat's milk on endocrine responses and isometric mid-thigh pull performance post back squat exercise. Twelve college-aged males volunteered to participate and reported to the lab on four occasions. The first visit included anthropometric measurement, one-repetition back squat (1RM), and familiarization with the isometric mid-thigh pull assessment (IMTP). During the subsequent three visits, five sets of eight repetitions of the back squat exercise at 80% of 1RM were performed. For these trials, the participants performed an IMTP and gave a saliva sample prior to, immediately after, 1 hr and 2 hr post exercise. After exercise, a treatment of low-fat chocolate goat's milk (355 ml, 225 kcal), low-fat chocolate cow's milk (355 ml, 225 kcal), or control (water 355 ml, 0 kcal) was given in a counterbalanced order. Saliva samples were analyzed for testosterone, cortisol, and dehydroepiandrosterone (DHEA). Cortisol and DHEA hormone were unaffected by exercise; however, testosterone values did increase significantly post exercise. For IMTP, there was a significant main effect for time (F = 8.41, p = .007) but no treatment or interactions effects. N changes were noted post supplementation for cortisol or DHEA, but testosterone was found to be significantly reduced in both diary treatments compared to control (F = 4.27, p = .022). Based upon these data, it appears that a single treatment of chocolate goat's or cow's milk results in similar endocrine alterations but both fail to enhance postexercise isometric strength following resistance exercise.

  13. Comparison of sympathetic nerve responses to neck and forearm isometric exercise

    NASA Technical Reports Server (NTRS)

    Steele, S. L. Jr; Ray, C. A.

    2000-01-01

    PURPOSE: Although the autonomic and cardiovascular responses to arm and leg exercise have been studied, the sympathetic adjustments to exercise of the neck have not. The purpose of the present study was twofold: 1) to determine sympathetic and cardiovascular responses to isometric contractions of the neck extensors and 2) to compare sympathetic and cardiovascular responses to isometric exercise of the neck and forearm. METHODS: Muscle sympathetic nerve activity (MSNA), mean arterial pressure (MAP), and heart rate were measured in nine healthy subjects while performing isometric neck extension (INE) and isometric handgrip (IHG) in the prone position. After a 3-min baseline period, subjects performed three intensities of INE for 2.5 min each: 1) unloaded (supporting head alone), 2) 10% maximal voluntary contraction (MVC), and 3) 30% MVC, then subjects performed two intensities (10% and 30% MVC) of IHG for 2.5 min. RESULTS: Supporting the head by itself did not significantly change any of the variables. During [NE, MAP significantly increased by 10 +/- 2 and 31 +/- 4 mm Hg and MSNA increased by 67 +/- 46 and 168 +/- 36 units/30 s for 10% and 30% MVC, respectively. IHG and INE evoked similar responses at 10% MVC, but IHG elicited higher peak MAP and MSNA at 30% MVC (37 +/- 7 mm Hg (P < 0.05) and 300 +/- 48 units/30 s (P < 0.01) for IHG, respectively). CONCLUSIONS: The data indicate that INE can elicit marked increases in MSNA and cardiovascular responses but that it evokes lower peak responses as compared to IHG. We speculate that possible differences in muscle fiber type composition, muscle mass, and/or muscle architecture of the neck and forearm are responsible for these differences in peak responses.

  14. Effects of caffeinated chewing gum on muscle pain during submaximal isometric exercise in individuals with fibromyalgia.

    PubMed

    Umeda, Masataka; Kempka, Laura; Weatherby, Amy; Greenlee, Brennan; Mansion, Kimberly

    2016-04-01

    Physical activity is important to manage symptom of fibromyalgia (FM); however, individuals with FM typically experience augmented muscle pain during exercise. This study examined the effects of caffeinated chewing gum on exercise-induced muscle pain in individuals with FM. This study was conducted with a double-blind, placebo-controlled, cross-over design. Twenty-three patients with FM completed a caffeine condition where they consumed a caffeinated chewing gum that contains 100mg of caffeine, and a placebo condition where they consumed a non-caffeinated chewing gum. They completed isometric handgrip exercise at 25% of their maximal strength for 3 min, and muscle pain rating (MPR) was recorded every 30s during exercise. Clinical pain severity was assessed in each condition using a pain questionnaire. The order of the two conditions was randomly determined. MPR increased during exercise, but caffeinated chewing gum did not attenuate the increase in MPR compared to placebo gum. Clinical pain severity was generally associated with the average MPR and the caffeine effects on MPR, calculated as difference in the average MPR between the two conditions. The results suggest that more symptomatic individuals with FM may experience greater exercise-induced muscle pain, but benefit more from caffeinated chewing gum to reduce exercise-induced muscle pain. Copyright © 2016 Elsevier Inc. All rights reserved.

  15. The effects of a 28-Hz vibration on arm muscle activity during isometric exercise.

    PubMed

    Mischi, Massimo; Cardinale, Marco

    2009-03-01

    The aim of this study was to evaluate activation and coactivation of biceps and triceps muscles during isometric exercise performed with and without superimposing a vibration stimulation. Twelve healthy volunteers (age = 22.7 +/- 2.6 yr) participated in this study. The subjects performed five trials of isometric elbow flexion and five trials of elbow extension with increasing levels of force in two conditions: vibration (V) and normal loading (C). V stimulation was characterized by a frequency of 28 Hz. Surface EMG activity of biceps and triceps muscles was simultaneously measured by bipolar surface electromyography and assessed by the estimation of the root mean square (RMS) of the electrical recordings over a fixed 5-s interval. Frequency analysis was adopted to estimate the RMS related to muscle activation and to exclude the harmonics generated by movement artifacts due to V. The analysis of the recordings revealed a significant EMG RMS increase when V was applied. On average, the EMG RMS of biceps and triceps during elbow flexion was, respectively, 26.1% (P < 0.05) and 18.2% (P = 0.15) higher than C. During elbow extension, the EMG RMS of biceps and triceps was 77.2% and 45.2% (P < 0.05) higher than C, respectively. The coactivation was assessed as the ratio between the activation of antagonist and agonist muscles during arm flexion and extension tasks. The results revealed an increase of coactivation during V exercise, especially for lighter loads. This study shows that V exercise at 28 Hz produces an increase of the activation and the coactivation of biceps and triceps. This exercise modality seems therefore suitable for various applications.

  16. Short-term vascular hemodynamic responses to isometric exercise in young adults and in the elderly.

    PubMed

    Hartog, Renee; Bolignano, Davide; Sijbrands, Eric; Pucci, Giacomo; Mattace-Raso, Francesco

    2018-01-01

    Vascular aging is known to induce progressive stiffening of the large elastic arteries, altering vascular hemodynamics under both rest and stress conditions. In this study, we aimed to investigate changes in vascular hemodynamics in response to isometric handgrip exercise across ages. We included 62 participants, who were divided into three age categories: 20-40 (n=22), 41-60 (n=20), and 61-80 (n=20) years. Vascular hemodynamics were measured using the Mobil-o-Graph ® based on the pulsatile pressure changes in the brachial artery. One-way ANOVA test was performed to analyze the changes induced by isometric handgrip exercise. After isometric handgrip exercise, aortic pulse wave velocity (PWV) increased by 0.10 m/s in the youngest, 0.06 m/s in the middle-age, and 0.02 m/s in the oldest age category. Changes in PWV strongly correlated with those in central systolic blood pressure (cSBP) ( r =0.878, P <0.01). After isometric exercise, the mean change of systolic blood pressure (SBP) was -1.9% in the youngest, 0.6% in the middle-aged, and 8.2% in the oldest subjects. Increasing handgrip strength was associated with an increase in SBP and cSBP (1.08 and 1.37 mmHg per 1 kg increase in handgrip strength, respectively, P =0.01). Finally, PWV was significantly associated with increasing handgrip strength with an increase of 0.05 m/s per 1 kg higher handgrip strength ( P =0.01). This study found increased blood pressure levels after isometric challenge and a strong association between handgrip strength and change in blood pressure levels and aortic stiffness in elderly subjects.

  17. Isometric strength training lowers the O2 cost of cycling during moderate-intensity exercise.

    PubMed

    Zoladz, Jerzy A; Szkutnik, Zbigniew; Majerczak, Joanna; Grandys, Marcin; Duda, Krzysztof; Grassi, Bruno

    2012-12-01

    The effect of maximal voluntary isometric strength training of knee extensor muscles on pulmonary V'O(2) on-kinetics, the O(2) cost of cycling and peak oxygen uptake (V'O(2peak)) in humans was studied. Seven healthy males (mean ± SD, age 22.3 ± 2.0 years, body weight 75.0 ± 9.2 kg, V'O(2peak) 49.5 ± 3.8 ml kg(-1) min(-1)) performed maximal isometric strength training lasting 7 weeks (4 sessions per week). Force during maximal voluntary contraction (MVC) increased by 15 % (P < 0.001) after 1 week of training, and by 19 % (P < 0.001) after 7 weeks of training. This increase in MVC was accompanied by no significant changes in the time constant of the V'O(2) on-kinetics during 6 min of moderate and heavy cycling intensities. Strength training resulted in a significant decrease (by ~7 %; P < 0.02) in the amplitude of the fundamental component of the V'O(2) on-kinetics, and therefore in a lower O(2) cost of cycling during moderate cycling intensity. The amplitude of the slow component of V'O(2) on-kinetics during heavy cycling intensity did not change with training. Training had no effect on the V'O(2peak), whereas the maximal power output reached at V'O(2peak) was slightly but significantly increased (P < 0.05). Isometric strength training rapidly (i.e., after 1 week) decreases the O(2) cost of cycling during moderate-intensity exercise, whereas it does not affect the amplitude of the slow component of the V'O(2) on-kinetics during heavy-intensity exercise. Isometric strength training can have beneficial effects on performance during endurance events.

  18. Effect of Isometric Hand Grip Exercises on Blood Flow and Placement of IV Catheters for Administration of Chemotherapy.

    PubMed

    Ozkaraman, Ayse; Yesilbalkan, Öznur Usta

    2016-04-01

    Complications may occur in the subcutaneous or subdermal tissues during IV administration of chemotherapy related to blood flow and catheter placement. Daily isometric hand grip exercises were evaluated for their effect on blood flow in the vessels of the nondominant arm before placement of IV catheters and the success rate of IV catheter placement on the first attempt. The study focused on patients with non-Hodgkin lymphoma receiving the first and second cycles of chemotherapy. The intervention group performed daily isometric hand grip exercises before chemotherapy with peripheral catheter insertion. The control group performed routine activities only. Blood flow was measured by ultrasound in the brachial artery (BA) and brachial vein (BV) of the nondominant arm before the first (T1) and second (T2) cycles of chemotherapy. Blood flow slightly increased in the intervention group at T2 compared to T1. In the control group, blood flow decreased in the BA and did not change in the BV at T2 compared to T1. The success rate for first-attempt placement of a peripheral IV catheter was the same for the intervention and control groups.

  19. Effect of cold air inhalation and isometric exercise on coronary blood flow and myocardial function in humans

    PubMed Central

    Muller, Matthew D.; Gao, Zhaohui; Drew, Rachel C.; Herr, Michael D.; Leuenberger, Urs A.

    2011-01-01

    The effects of cold air inhalation and isometric exercise on coronary blood flow are currently unknown, despite the fact that both cold air and acute exertion trigger angina in clinical populations. In this study, we used transthoracic Doppler echocardiography to measure coronary blood flow velocity (CBV; left anterior descending coronary artery) and myocardial function during cold air inhalation and handgrip exercise. Ten young healthy subjects underwent the following protocols: 5 min of inhaling cold air (cold air protocol), 5 min of inhaling thermoneutral air (sham protocol), 2 min of isometric handgrip at 30% of maximal voluntary contraction (grip protocol), and 5 min of isometric handgrip at 30% maximal voluntary contraction while breathing cold air (cold + grip protocol). Heart rate, blood pressure, inspired air temperature, CBV, myocardial function (tissue Doppler imaging), O2 saturation, and pulmonary function were measured. The rate-pressure product (RPP) was used as an index of myocardial O2 demand, whereas CBV was used as an index of myocardial O2 supply. Compared with the sham protocol, the cold air protocol caused a significantly higher RPP, but there was a significant reduction in CBV. The cold + grip protocol caused a significantly greater increase in RPP compared with the grip protocol (P = 0.045), but the increase in CBV was significantly less (P = 0.039). However, myocardial function was not impaired during the cold + grip protocol relative to the grip protocol alone. Collectively, these data indicate that there is a supply-demand mismatch in the coronary vascular bed when cold ambient air is breathed during acute exertion but myocardial function is preserved, suggesting an adequate redistribution of blood flow. PMID:21940852

  20. Effectiveness of various isometric exercises at improving bone strength in cortical regions prone to distal tibial stress fractures.

    PubMed

    Florio, C S

    2018-06-01

    A computational model was used to compare the local bone strengthening effectiveness of various isometric exercises that may reduce the likelihood of distal tibial stress fractures. The developed model predicts local endosteal and periosteal cortical accretion and resorption based on relative local and global measures of the tibial stress state and its surface variation. Using a multisegment 3-dimensional leg model, tibia shape adaptations due to 33 combinations of hip, knee, and ankle joint angles and the direction of a single or sequential series of generated isometric resultant forces were predicted. The maximum stress at a common fracture-prone region in each optimized geometry was compared under likely stress fracture-inducing midstance jogging conditions. No direct correlations were found between stress reductions over an initially uniform circular hollow cylindrical geometry under these critical design conditions and the exercise-based sets of active muscles, joint angles, or individual muscle force and local stress magnitudes. Additionally, typically favorable increases in cross-sectional geometric measures did not guarantee stress decreases at these locations. Instead, tibial stress distributions under the exercise conditions best predicted strengthening ability. Exercises producing larger anterior distal stresses created optimized tibia shapes that better resisted the high midstance jogging bending stresses. Bent leg configurations generating anteriorly directed or inferiorly directed resultant forces created favorable adaptations. None of the studied loads produced by a straight leg was significantly advantageous. These predictions and the insight gained can provide preliminary guidance in the screening and development of targeted bone strengthening techniques for those susceptible to distal tibial stress fractures. Copyright © 2018 John Wiley & Sons, Ltd.

  1. Comparison of isometric cervical flexor and isometric cervical extensor system exercises on patients with neuromuscular imbalance and cervical crossed syndrome associated forward head posture.

    PubMed

    Lee, Jaejin; Kim, Dohyeon; Yu, Kyunghoon; Cho, Youngki; You, Joshua H

    2018-01-01

    Isometric cervical flexor system exercise (ICF) and isometric cervical extensor system exercise (ICE) are cervical stabilization techniques that have been used to restore cervical crossed syndrome (CCS)-associated forward head posture. However, the therapeutic effects and underlying motor control mechanisms remain elusive. The purpose of present study was investigating the concurrent therapeutic effects of ICF and ICE on muscle size, muscle imbalance ratio, and muscle recruitment sequence using ultrasound imaging and electromyography. A total of 18 participants (7 females; age=24±4.0 years) with CCS associated with forward head posture underwent ICF and ICE. Paired t-test analysis was used for statistical analysis. Paired t-test analysis showed that sternocleidomastoid thickness was greater during ICF than ICE. Similarly, cross-sectional area and horizontal thickness of the longus colli were greater during ICE than ICF. The upper trapezius/lower trapezius muscle imbalance ratio and the pectoralis major/lower trapezius muscle imbalance ratio were significantly decreased during the application of ICE compared to ICF. These results provide compelling, mechanistic evidence as to how ICE is more beneficial for the restoration of neuromuscular imbalance than ICF in individuals with CCS.

  2. A pilot randomised controlled trial of the feasibility of using body scan and isometric exercises for reducing urge to smoke in a smoking cessation clinic

    PubMed Central

    Al-Chalabi, Lemees; Prasad, Neha; Steed, Lucy; Stenner, Sarah; Aveyard, Paul; Beach, Jane; Ussher, Michael

    2008-01-01

    Background The main cause of relapse in smokers attempting to quit is inability to resist urges to smoke. Pharmacotherapy ameliorates but does not entirely prevent urges to smoke when abstinent, so other methods to resist urges to smoke might be helpful. Exercise is effective, but aerobic exercise is often impractical when urges strike. Two techniques, body scan and isometric exercise, have been shown to reduce urge intensity and nicotine withdrawal symptoms in temporarily abstinent smokers. It is unclear whether they would be used or effective in typical smokers attempting to quit. Methods In a pilot trial set in a UK smoking cessation clinic, 20 smokers were randomised to receive emails containing .mp3 files and .pdf illustrations of the instructions for doing the body scan and isometric exercises. Twenty smokers received no other intervention, although all 40 were receiving weekly behavioural support and nicotine replacement therapy. Carbon monoxide confirmed abstinence, nicotine withdrawal symptoms, urges to smoke, and use of the techniques to resist urges were recorded weekly for four weeks after quit day. Results 60–80% of quitters reported using the isometric exercises each week and 40–70% reported using the body scan to deal with urges. On average, these techniques were rated as 'slightly helpful' for controlling the urges. There were no large or significant differences in withdrawal symptoms or urge intensity between the two groups. The risk ratio and 95% confidence interval for exercises compared with controls for prolonged confirmed abstinence at four weeks was 0.82 (0.44–1.53). 81% of quitters intended to continue using isometric exercises and 25% body scan, while 81% and 50% respectively would recommend using these techniques to others trying to stop. Conclusion Isometric exercises, and to a lesser extent body scan, were popular and perceived as somewhat helpful by quitters. The trial showed that these techniques were used and a larger trial

  3. Cardiovascular responses to water ingestion at rest and during isometric handgrip exercise.

    PubMed

    Mendonca, Goncalo V; Teixeira, Micael S; Pereira, Fernando D

    2012-07-01

    Water drinking activates sympathetic vasoconstriction in healthy young adults; however, this is not accompanied by a concomitant increase in resting blood pressure. It is not known whether the water pressor effect is unmasked by a physiological condition such as exercise. Therefore, we examined the effect of water ingestion (50 vs. 500 mL) on the cardiovascular and autonomic responses to isometric handgrip in 17 healthy participants (9 men, 8 women, aged 28.4 ± 9.7 years). Beat-to-beat blood pressure and R-R intervals were recorded in both conditions at rest (pre- and post-ingestion) and during handgrip at 30% of maximal voluntary contraction. R-R series were spectrally decomposed using an autoregressive approach. Water ingestion did not interact with the increase in mean arterial pressure (MAP) from rest to exercise, which was similar between conditions. In contrast, there was an overall bradycardic effect of water and this was accompanied by increased high frequency power (condition main effect, p < 0.05). When the differences in high frequency power between conditions were controlled for, MAP was significantly higher after drinking 500 mL of water (condition main effect, p < 0.05). In addition, water ingestion attenuated the increase in the low to high frequency power ratio from rest to handgrip (interaction effect, p < 0.05). In conclusion, the rise in blood pressure post-water ingestion is prevented both at rest and during isometric handgrip. Interestingly, this is not sustained after controlling for the enhanced vagal drive caused by water ingestion. Therefore, the mechanisms underlying this response most likely depend on reflex bradycardia of vagal origin.

  4. The efficacy of isometric resistance training utilizing handgrip exercise for blood pressure management: A randomized trial.

    PubMed

    Carlson, Debra J; Inder, Jodie; Palanisamy, Suresh K A; McFarlane, James R; Dieberg, Gudrun; Smart, Neil A

    2016-12-01

    Hypertension is a major risk factor contributing to cardiovascular disease, which is the number one cause of deaths worldwide. Although antihypertensive medications are effective at controlling blood pressure, current first-line treatment for hypertension is nonpharmacological lifestyle modifications. Recent studies indicate that isometric resistance training (IRT) may also be effective for assisting with blood pressure management. The aim of this study was to determine the efficacy of IRT for blood pressure management and the suitability of a low-intensity working control group. Forty hypertensive individuals, aged between 36 and 65 years, conducted IRT for 8 weeks. Participants were randomized into 2 groups, working at an intensity of either 5% or 30% of their maximum voluntary contraction. Participants performed 4 × 2 minute isometric handgrip exercises with their nondominant hand, each separated by a 3-minute rest period, 3 days a week. Blood pressure measurements were conducted at baseline and at the end of the protocol using a Finometer. Eight weeks of isometric resistance training resulted in a 7-mmHg reduction of resting systolic blood pressure (SBP) (136 ± 12 to 129 ± 15; P = 0.04) in the 30% group. Reductions of 4 mmHg were also seen in mean arterial pressure (MAP) (100 ± 8 to 96 ± 11; P = 0.04) in the 30% group. There were no statistically significant reductions in diastolic blood pressure for the 30% group, or any of the data for the 5% group. Isometric resistance training conducted using handgrip exercise at 30% of maximum voluntary contraction significantly reduced SBP and MAP. A lack of reduction in blood pressure in the 5% group indicates that a low-intensity group may be suitable as a working control for future studies.

  5. Isometric Exercise for the Cervical Extensors Can Help Restore Physiological Lordosis and Reduce Neck Pain: A Randomized Controlled Trial.

    PubMed

    Alpayci, Mahmut; İlter, Server

    2017-09-01

    The aim of this study was to investigate whether isometric neck extension exercise restores physiological cervical lordosis and reduces pain. Sixty-five patients with loss of cervical lordosis were randomly assigned to exercise (27 women, 7 men; mean age, 32.82 ± 8.83 yrs) and control (26 women, 5 men; mean age, 33.48 ± 9.67 yrs) groups. Both groups received nonsteroidal anti-inflammatory drugs for 10 days. The exercise group received additional therapy as a home exercise program, which consisted of isometric neck extension for 3 mos. Neck pain severity and cervical lordosis were measured at baseline and at 3 mos after baseline. Compared with baseline levels, cervical lordosis angle was significantly improved in the exercise group (P < 0.001) but not in the control group (P = 0.371) at the end of 3 mos. Moreover, the exercise group was significantly superior to the control group considering the number of patients in whom cervical lordosis angle returned to physiological conditions (85.2% vs. 22.5%; P < 0.001). At the end of 3 mos, pain intensity was significantly reduced in both groups compared with baseline levels (for all, P < 0.001). Nevertheless, considering the change from baseline to month 3, the reduction in pain was about twice in the exercise group compared with the control group (P < 0.001). Isometric neck extension exercise improves cervical lordosis and pain.

  6. Role of endothelin-1 in choroidal blood flow regulation during isometric exercise in healthy humans.

    PubMed

    Fuchsjäger-Mayrl, Gabriele; Luksch, Alexandra; Malec, Magdalena; Polska, Elzbieta; Wolzt, Michael; Schmetterer, Leopold

    2003-02-01

    There is evidence that the choroid has some autoregulatory capacity in response to changes in ocular perfusion pressure (OPP). The mediators of this response are hitherto unidentified. The hypothesis for the current study was that endothelin (ET)-1 and/or angiotensin (ANF)-II may be involved in choroidal vasoconstriction during an increase in OPP. To test this hypothesis a randomized, double-masked, placebo-controlled, three way crossover study was performed in 12 healthy male volunteers. Subjects received on different study days intravenous infusions of the specific ET(A) receptor antagonist BQ-123, the angiotensin converting enzyme inhibitor enalapril or placebo. During these infusion periods subjects were asked to squat for 6 minutes. Choroidal blood flow was measured using a confocal laser Doppler flowmeter and ocular perfusion pressure (OPP) was calculated from mean arterial pressure and intraocular pressure. BQ-123 and enalapril had no effect on basal blood pressure, pulse rate, intraocular pressure, or choroidal blood flow. During isometric exercise, a pronounced increase in mean arterial pressure paralleled by an increase in OPP was observed. Although choroidal blood flow slightly increased during squatting, the increase was much less pronounced than the increase in OPP, indicating some regulatory potential of the choroid. Enalapril did not alter the choroidal pressure-flow relationship during isometric exercise, but BQ-123 induced a significant leftward shift of the pressure-flow curve (P < 0.001). The present data indicate that ET-1, but not ANG II, plays a role in choroidal blood flow regulation during isometric exercise in healthy humans. Hence, impaired choroidal autoregulation in patients with ocular vascular diseases may arise from an altered endothelin system. Further studies in such patients are warranted to verify this hypothesis.

  7. The safety of isometric exercise: Rethinking the exercise prescription paradigm for those with stage 1 hypertension.

    PubMed

    Wiles, Jonathan D; Taylor, Katrina; Coleman, Damian; Sharma, Rajan; O'Driscoll, Jamie M

    2018-03-01

    Few studies have investigated the relative safety of prescribing isometric exercise (IE) to reduce resting blood pressure (BP). This study aimed to ascertain the safety of the hemodynamic response during an IE wall squat protocol.Twenty-six hypertensive (BP of 120-139 mm Hg systolic and/or 80-90 mm Hg diastolic) males (45 ± 8 years; 1.78 ± 0.07 m; 89.7 ± 12.3 kg; mean ± SD), visited the laboratory on 2 separate occasions. Heart rate (HR) and BP were measured at rest and continuously throughout exercise. In visit 1, participants completed a continuous incremental isometric wall squat exercise test, starting at 135° of knee flexion, decreasing by 10° every 2 minutes until 95° (final stage). Exercise was terminated upon completion of the test or volitional fatigue. The relationship between knee joint angle and mean HR was used to calculate the participant-specific knee joint angle required to elicit a target HR of 95% HRpeak. This angle was used to determine exercise intensity for a wall squat training session consisting of 4 × 2 minute bouts (visit 2).Systolic BPs during the exercise test and training were 173 ± 21 mm Hg and 171 ± 19 mm Hg, respectively, (P > .05) and were positively related (r = 0.73, P < .05) with ratio limits of agreement (LoA) of 0.995 ×/÷ 1.077. Diastolic BPs were 116 ± 14 mm Hg and 113 ± 11 mm Hg, respectively, (P > .05) and were positively related (r = 0.42, P < .05) with ratio LoA of 0.99 ×/÷ 1.107. No participant recorded a systolic BP > 250 mm Hg. Diastolic BP values > 115 mm Hg were recorded in 12 participants during the incremental test and 6 participants during the training session. Peak rate pressure product was 20681 ± 3911 mm Hg bpm during the IE test and was lower (18074 ± 3209 mm Hg bpm) during the IE session (P = .002). No adverse effects were reported.Based on the current ACSM guidelines for aerobic exercise termination

  8. Serratus anterior and lower trapezius muscle activities during multi-joint isotonic scapular exercises and isometric contractions.

    PubMed

    Tsuruike, Masaaki; Ellenbecker, Todd S

    2015-02-01

    Proper scapular function during humeral elevation, such as upward rotation, external rotation, and posterior tilting of the scapula, is necessary to prevent shoulder injury. However, the appropriate intensity of rehabilitation exercise for the periscapular muscles has yet to be clarified. To identify the serratus anterior, lower trapezius, infraspinatus, and posterior deltoid muscle activities during 2 free-motion exercises using 3 intensities and to compare these muscle activities with isometric contractions during quadruped shoulder flexion and external rotation and abduction of the glenohumeral joint. Cross-sectional study. Health Science Laboratory. A total of 16 uninjured, healthy, active, male college students (age = 19.5 ± 1.2 years, height = 173.1 ± 6.5 cm, weight = 68.8 ± 6.6 kg). Mean electromyographic activity normalized by the maximal voluntary isometric contraction was analyzed across 3 intensities and 5 exercises. Intraclass correlation coefficients were calculated for electromyographic activity of the 4 muscles in each free-motion exercise. Significant interactions in electromyographic activity were observed between intensities and exercises (P < .05). The quadruped shoulder-flexion exercise activated all 4 muscles compared with other exercises. Also, the modified robbery free-motion exercise activated the serratus anterior, lower trapezius, and infraspinatus compared with the lawn-mower free-motion exercise. However, neither exercise showed a difference in posterior deltoid electromyographic activity. Three intensities exposed the nature of the periscapular muscle activities across the different exercises. The free-motion exercise in periscapular muscle rehabilitation may not modify serratus anterior, lower trapezius, and infraspinatus muscle activities unless knee-joint extension is limited.

  9. Use of diffuse optical spectroscopy to monitor muscle and brain oxygenation dynamics during isometric and isokinetic exercise

    NASA Astrophysics Data System (ADS)

    Ganesan, Goutham; Cotter, Joshua; Reuland, Warren; Warren, Robert V.; Mirzaei Zarandi, Soroush M.; Cerussi, Albert E.; Tromberg, Bruce J.; Galassetti, Pietro

    2013-03-01

    The use of near-infrared time-resolved spectroscopy (TRS-20, Hamamatsu Corporation) in two resistance type exercise applications in human subjects is described. First, using isometric flexion of the biceps, we compared the magnitude and relevance of tissue hemoglobin concentration and oxygen saturation (stO2) changes when assuming constant scattering versus continuous measurement of reduced scattering coefficients at three wavelengths. It was found that the assumption of constant scattering resulted in significant errors in hemoglobin concentration assessment during sustained isometric contractions. Secondly, we tested the effect of blood flow restriction (BFR) on oxygenation in a muscle (vastus medialis oblique, VMO) and in the prefrontal cortex (PFC) of the brain. The BFR training technique resulted in considerably more fatigability in subjects, and correlated with reduced muscle stO2 between sets of exertion. Additionally, exercise with BFR resulted in greater PFC deoxygenation than a condition with equivalent work performance but no BFR. These experiments demonstrate novel applications for diffuse optical spectroscopy in strength testing and targeted muscle rehabilitation.

  10. Beta-1 vs. beta-2 adrenergic control of coronary blood flow during isometric handgrip exercise in humans.

    PubMed

    Maman, Stephan R; Vargas, Alvaro F; Ahmad, Tariq Ali; Miller, Amanda J; Gao, Zhaohui; Leuenberger, Urs A; Proctor, David N; Muller, Matthew D

    2017-08-01

    During exercise, β-adrenergic receptors are activated throughout the body. In healthy humans, the net effect of β-adrenergic stimulation is an increase in coronary blood flow. However, the role of vascular β1 vs. β2 receptors in coronary exercise hyperemia is not clear. In this study, we simultaneously measured noninvasive indexes of myocardial oxygen supply (i.e., blood velocity in the left anterior descending coronary artery; Doppler echocardiography) and demand [i.e., rate pressure product (RPP) = heart rate × systolic blood pressure) and tested the hypothesis that β1 blockade with esmolol improves coronary exercise hyperemia compared with nonselective β-blockade with propranolol. Eight healthy young men received intravenous infusions of esmolol, propranolol, and saline on three separate days in a single-blind, randomized, crossover design. During each infusion, subjects performed isometric handgrip exercise until fatigue. Blood pressure, heart rate, and coronary blood velocity (CBV) were measured continuously, and RPP was calculated. Changes in parameters from baseline were compared with paired t -tests. Esmolol (Δ = 3296 ± 1204) and propranolol (Δ = 2997 ± 699) caused similar reductions in peak RPP compared with saline (Δ = 5384 ± 1865). In support of our hypothesis, ΔCBV with esmolol was significantly greater than with propranolol (7.3 ± 2.4 vs. 4.5 ± 1.6 cm/s; P = 0.002). This effect was also evident when normalizing ΔCBV to ΔRPP. In summary, not only does selective β1 blockade reduce myocardial oxygen demand during exercise, but it also unveils β2-receptor-mediated coronary exercise hyperemia. NEW & NOTEWORTHY In this study, we evaluated the role of vascular β1 vs. β2 receptors in coronary exercise hyperemia in a single-blind, randomized, crossover study in healthy men. In response to isometric handgrip exercise, blood flow velocity in the left anterior descending coronary artery was significantly greater with esmolol compared with

  11. Serratus Anterior and Lower Trapezius Muscle Activities During Multi-Joint Isotonic Scapular Exercises and Isometric Contractions.

    PubMed

    Tsuruike, Masaaki; Ellenbecker, Todd

    2014-11-14

    Context :  Proper scapular function during humeral elevation, such as upward rotation, external rotation, and posterior tilting of the scapula, is necessary to prevent shoulder injury. However, the appropriate intensity of rehabilitation exercise for the periscapular muscles has yet to be clarified. Objective :  To identify the serratus anterior, lower trapezius, infraspinatus, and posterior deltoid muscle activities during 2 free-motion exercises using 3 intensities and to compare these muscle activities with isometric contractions during quadruped shoulder flexion and external rotation and abduction of the glenohumeral joint. Design :  Cross-sectional study. Setting :  Health Science Laboratory. Patients or Other Participants :  A total of 16 uninjured, healthy, active, male college students (age = 19.5 ± 1.2 years, height = 173.1 ± 6.5 cm, weight = 68.8 ± 6.6 kg). Main Outcome Measure(s) :  Mean electromyographic activity normalized by the maximal voluntary isometric contraction was analyzed across 3 intensities and 5 exercises. Intraclass correlation coefficients were calculated for electromyographic activity of the 4 muscles in each free-motion exercise. Results :  Significant interactions in electromyographic activity were observed between intensities and exercises (P < .05). The quadruped shoulder-flexion exercise activated all 4 muscles compared with other exercises. Also, the modified robbery free-motion exercise activated the serratus anterior, lower trapezius, and infraspinatus compared with the lawn-mower free-motion exercise. However, neither exercise showed a difference in posterior deltoid electromyographic activity. Conclusions :  Three intensities exposed the nature of the periscapular muscle activities across the different exercises. The free-motion exercise in periscapular muscle rehabilitation may not modify serratus anterior, lower trapezius, and infraspinatus muscle activities unless knee-joint extension is limited.

  12. Serratus Anterior and Lower Trapezius Muscle Activities During Multi-Joint Isotonic Scapular Exercises and Isometric Contractions

    PubMed Central

    Tsuruike, Masaaki; Ellenbecker, Todd S.

    2015-01-01

    Context: Proper scapular function during humeral elevation, such as upward rotation, external rotation, and posterior tilting of the scapula, is necessary to prevent shoulder injury. However, the appropriate intensity of rehabilitation exercise for the periscapular muscles has yet to be clarified. Objective: To identify the serratus anterior, lower trapezius, infraspinatus, and posterior deltoid muscle activities during 2 free-motion exercises using 3 intensities and to compare these muscle activities with isometric contractions during quadruped shoulder flexion and external rotation and abduction of the glenohumeral joint. Design: Cross-sectional study. Setting: Health Science Laboratory. Patients or Other Participants: A total of 16 uninjured, healthy, active, male college students (age = 19.5 ± 1.2 years, height = 173.1 ± 6.5 cm, weight = 68.8 ± 6.6 kg). Main Outcome Measure(s): Mean electromyographic activity normalized by the maximal voluntary isometric contraction was analyzed across 3 intensities and 5 exercises. Intraclass correlation coefficients were calculated for electromyographic activity of the 4 muscles in each free-motion exercise. Results: Significant interactions in electromyographic activity were observed between intensities and exercises (P < .05). The quadruped shoulder-flexion exercise activated all 4 muscles compared with other exercises. Also, the modified robbery free-motion exercise activated the serratus anterior, lower trapezius, and infraspinatus compared with the lawn-mower free-motion exercise. However, neither exercise showed a difference in posterior deltoid electromyographic activity. Conclusions: Three intensities exposed the nature of the periscapular muscle activities across the different exercises. The free-motion exercise in periscapular muscle rehabilitation may not modify serratus anterior, lower trapezius, and infraspinatus muscle activities unless knee-joint extension is limited. PMID:25689561

  13. The effect of short-term isometric training on core/torso stiffness.

    PubMed

    Lee, Benjamin; McGill, Stuart

    2017-09-01

    "Core" exercise is a basic part of many physical training regimens with goals ranging from rehabilitation of spine and knee injuries to improving athletic performance. Core stiffness has been proposed to perform several functions including reducing pain by minimising joint micro-movements, and enhancing strength and speed performance. This study probes the links between a training approach and immediate but temporary changes in stiffness. Passive and active stiffness was measured on 24 participants; 12 having little to no experience in core training (inexperienced), and the other 12 being athletes experienced to core training methods; before and after a 15 min bout of isometric core exercises. Passive stiffness was assessed on a "frictionless" bending apparatus and active stiffness assessed via a quick release mechanism. Short-term isometric core training increased passive and active stiffness in most directions for both inexperienced and experienced participants, passive left lateral bend among experienced participants being the exception (P < 0.05). There was no difference between the inexperienced and experienced groups. The results confirm that the specific isometric training exercise approach tested here can induce immediate changes in core stiffness, in this case following a single session. This may influence performance and injury resilience for a brief period.

  14. Sweat production during global heating and during isometric exercise in people with diabetes.

    PubMed

    Petrofsky, Jerrold Scott; Lee, Scott; Patterson, Chris; Cole, Melissa; Stewart, Brian

    2005-11-01

    While sweat production in response to heat is impaired in people with diabetes, sweat production has not been examined during isometric exercise. Eight subjects with type 2 diabetes and 9 control subjects exerted a fatiguing isometric contraction of the handgrip muscles at a tension of 40% of the maximum voluntary strength (MVC) after exposure to a 32 deg C environment for 30 min. compared to 10 controls and 10 subjects with diabetes exposed to a 39 deg C environment. Sweat was impaired to all areas of the body during heat exposure in patients with diabetes under both environmental conditions. For example, on the chest, the average sweat rates after exposure to the 32 deg environment was 259.2 +/- 55.2 nanoliters/min in control subjects and 198.3 +/- 46.2 nanoliters/min for subjects with diabetes. Compared to the 32 deg C environment, control subjects increased sweat in all 4 areas proportionally more than subjects with diabetes. Sudomotor rhythm was present in sweat in control subjects at a rate of repetition of 11 and 50 seconds but almost absent in subjects with diabetes. During exercise, sweat rates slowly increased from the beginning to the end of the exercise. But the head of the subjects with diabetes showed hypersweating while the other areas showed diminished sweating compared to control subjects. Thus some of the impairment in sweating may be due to central mechanisms associated with heat sensitivity or in the hypothalamus and not to the sweat glands themselves.

  15. Effect of long-term isometric training on core/torso stiffness.

    PubMed

    Lee, Benjamin C Y; McGill, Stuart M

    2015-06-01

    Although core stiffness enhances athletic performance traits, controversy exists regarding the effectiveness of isometric vs. dynamic core training methods. This study aimed to determine whether long-term changes in stiffness can be trained, and if so, what is the most effective method. Twenty-four healthy male subjects (23 ± 3 years; 1.8 ± 0.06 m; 77.5 ± 10.8 kg) were recruited for passive and active stiffness measurements before and after a 6-week core training intervention. Twelve subjects (22 ± 2 years; 1.8 ± 0.08 m; 78.3 ± 12.3 kg) were considered naive to physical and core exercise. The other 12 subjects (24 ± 3 years; 1.8 ± 0.05 m; 76.8 ± 9.7 kg) were Muay Thai athletes (savvy). A repeated-measures design compared core training methods (isometric vs. dynamic, with a control group) and subject training experience (naive vs. savvy) before and after a 6-week training period. Passive stiffness was assessed on a "frictionless" bending apparatus and active stiffness assessed through a quick release mechanism. Passive stiffness increased after the isometric training protocol. Dynamic training produced a smaller effect, and as expected, there was no change in the control group. Active stiffness did not change in any group. Comparisons between subject and training groups did not reveal any interactions. Thus, an isometric training approach was superior in terms of enhancing core stiffness. This is important since increased core stiffness enhances load bearing ability, arrests painful vertebral micromovements, and enhances ballistic distal limb movement. This may explain the efficacy reported for back and knee injury reduction.

  16. Cerebral mechanisms underlying the effects of music during a fatiguing isometric ankle-dorsiflexion task.

    PubMed

    Bigliassi, Marcelo; Karageorghis, Costas I; Nowicky, Alexander V; Orgs, Guido; Wright, Michael J

    2016-10-01

    The brain mechanisms by which music-related interventions ameliorate fatigue-related symptoms during the execution of fatiguing motor tasks are hitherto under-researched. The objective of the present study was to investigate the effects of music on brain electrical activity and psychophysiological measures during the execution of an isometric fatiguing ankle-dorsiflexion task performed until the point of volitional exhaustion. Nineteen healthy participants performed two fatigue tests at 40% of maximal voluntary contraction while listening to music or in silence. Electrical activity in the brain was assessed by use of a 64-channel EEG. The results indicated that music downregulated theta waves in the frontal, central, and parietal regions of the brain during exercise. Music also induced a partial attentional switching from associative thoughts to task-unrelated factors (dissociative thoughts) during exercise, which led to improvements in task performance. Moreover, participants experienced a more positive affective state while performing the isometric task under the influence of music. © 2016 Society for Psychophysiological Research.

  17. Trunk muscle activation during dynamic weight-training exercises and isometric instability activities.

    PubMed

    Hamlyn, Nicolle; Behm, David G; Young, Warren B

    2007-11-01

    The purpose of this study was to examine the extent of activation in various trunk muscles during dynamic weight-training and isometric instability exercises. Sixteen subjects performed squats and deadlifts with 80% 1 repetition maximum (1RM), as well as with body weight as resistance and 2 unstable calisthenic-type exercises (superman and sidebridge). Electromyographic (EMG) activity was measured from the lower abdominals (LA), external obliques (EO), upper lumbar erector spinae (ULES), and lumbar-sacral erector spinae (LSES) muscle groups. Results indicated that the LSES EMG activity during the 80% 1RM squat significantly exceeded 80% 1RM deadlift LSES EMG activity by 34.5%. The LSES EMG activity of the 80% 1RM squat also exceeded the body weight squat, deadlift, superman, and sidebridge by 56, 56.6, 65.5, and 53.1%, respectively. The 80% 1RM deadlift ULES EMG activity significantly exceeded the 80% 1RM squat exercise by 12.9%. In addition, the 80% 1RM deadlift ULES EMG activity also exceeded the body weight squat, deadlift, superman, and sidebridge exercises by 66.7, 65.5, 69.3, and 68.6%, respectively. There were no significant changes in EO or LA activity. Therefore, the augmented activity of the LSES and ULES during 80% 1RM squat and deadlift resistance exercises exceeded the activation levels achieved with the same exercises performed with body weight and selected instability exercises. Individuals performing upright, resisted, dynamic exercises can achieve high trunk muscle activation and thus may not need to add instability device exercises to augment core stability training.

  18. Muscle Activation Differs between Three Different Knee Joint-Angle Positions during a Maximal Isometric Back Squat Exercise

    PubMed Central

    Jarbas da Silva, Josinaldo; Jon Schoenfeld, Brad; Nardi, Priscyla Silva Monteiro; Pecoraro, Silvio Luis; D'Andréa Greve, Julia Maria; Hartigan, Erin

    2016-01-01

    The purpose of this study was to compare muscle activation of the lower limb muscles when performing a maximal isometric back squat exercise over three different positions. Fifteen young, healthy, resistance-trained men performed an isometric back squat at three knee joint angles (20°, 90°, and 140°) in a randomized, counterbalanced fashion. Surface electromyography was used to measure muscle activation of the vastus lateralis (VL), vastus medialis (VM), rectus femoris (RF), biceps femoris (BF), semitendinosus (ST), and gluteus maximus (GM). In general, muscle activity was the highest at 90° for the three quadriceps muscles, yet differences in muscle activation between knee angles were muscle specific. Activity of the GM was significantly greater at 20° and 90° compared to 140°. The BF and ST displayed similar activation at all joint angles. In conclusion, knee position alters muscles activation of the quadriceps and gluteus maximus muscles. An isometric back squat at 90° generates the highest overall muscle activation, yet an isometric back squat at 140° generates the lowest overall muscle activation of the VL and GM only. PMID:27504484

  19. Ways of increasing muscular activity by means of isometric muscular exertion

    NASA Technical Reports Server (NTRS)

    Kovalik, A. V.

    1980-01-01

    The effect of isometric muscular exertion on the human body was investigated by having subjects perform basic movements in a sitting position in the conventional manner with additional muscle tension at 50% maximum force and at maximum force. The pulse, arterial pressure, skin temperature, respiratory rate, minute respiratory volume and electrical activity of the muscles involved were all measured. Performance of the exercises with maximum muscular exertion for 20 sec and without movement resulted in the greatest shifts in these indices; in the conventional manner substantial changes did not occur; and with isometric muscular exertion with 50% maximum force with and without movement, optimal functional shifts resulted. The latter is recommended for use in industrial exercises for the prevention of hypodynamia. Ten exercises are suggested.

  20. Effect of bed rest and exercise on body balance

    NASA Technical Reports Server (NTRS)

    Haines, R. F.

    1974-01-01

    A battery of 11 body balance tests was administered to 7 men before and after 14 days of bedrest. Seven men who had not undergone bed rest served as controls. During bed rest, each subject underwent daily either isotonic, isometric, or no leg exercise. The results showed that, for the bed-rested no exercise, isotonic exercise, and isometric exercise groups, 2 weeks of bed rest produces significant body balance decrements on 3, 4, and 5 of the 11 tests, respectively. Daily leg exercise did not prevent the debilitating effects of bed rest on body balance. After bed rest, balance skill was relearned rapidly so that in most tests, performance had reached prebed-rest levels by the third recovery day. These data suggest that balance impairment is not due to loss of muscular strength in the legs but, perhaps, to a bed-rest-related change in the neurally coded information to postural control centers.

  1. Isometric pre-conditioning blunts exercise-induced muscle damage but does not attenuate changes in running economy following downhill running.

    PubMed

    Lima, Leonardo C R; Bassan, Natália M; Cardozo, Adalgiso C; Gonçalves, Mauro; Greco, Camila C; Denadai, Benedito S

    2018-05-08

    Running economy (RE) is impaired following unaccustomed eccentric-biased exercises that induce muscle damage. It is also known that muscle damage is reduced when maximal voluntary isometric contractions (MVIC) are performed at a long muscle length 2-4 days prior to maximal eccentric exercise with the same muscle, a phenomenon that can be described as isometric pre-conditioning (IPC). We tested the hypothesis that IPC could attenuate muscle damage and changes in RE following downhill running. Thirty untrained men were randomly assigned into experimental or control groups and ran downhill on a treadmill (-15%) for 30 min. Participants in the experimental group completed 10 MVIC in a leg press machine two days prior to downhill running, while participants in the control group did not perform IPC. The magnitude of changes in muscle soreness determined 48 h after downhill running was greater for the control group (122 ± 28 mm) than for the experimental group (92 ± 38 mm). Isometric peak torque recovered faster in the experimental group compared with the control group (3 days vs. no full recovery, respectively). No significant effect of IPC was found for countermovement jump height, serum creatine kinase activity or any parameters associated with RE. These results supported the hypothesis that IPC attenuates changes in markers of muscle damage. The hypothesis that IPC attenuates changes in RE was not supported by our data. It appears that the mechanisms involved in changes in markers of muscle damage and parameters associated with RE following downhill running are not completely shared. Copyright © 2018 Elsevier B.V. All rights reserved.

  2. The acute effects of bodyweight suspension exercise on muscle activation and muscular fatigue.

    PubMed

    Cayot, Trent E; Lauver, Jakob D; Scheuermann, Barry W

    2017-07-01

    This investigation examined effects of two exercise modes (barbell, BB; bodyweight suspension, BWS) on muscle activation, resistance load, and fatigue. During session one, nine resistance-trained males completed an elbow flexion one-repetition maximum (1RM). During sessions two and three, subjects completed standing biceps curls to fatigue at 70% 1RM utilizing a randomized exercise mode. Surface electromyography (sEMG) recorded muscle activation of the biceps brachii, triceps brachii, anterior deltoid, posterior deltoid, rectus abdominis, and erector spinae. BWS resistance load was measured using a force transducer. Standing maximal voluntary isometric contractions of the elbow flexors recorded at 90° were used to determine the isometric force decrement and rate of fatigue (ROF) during exercise. sEMG and resistance load data were divided into 25% contraction duration bins throughout the concentric phase. BWS resulted in a 67.7 ± 7.4% decline in resistance load throughout the concentric phase (p ≤ 0.05). As a result, BB elicited higher mean resistance loads (31.4 ± 4.0 kg) and biceps brachii sEMG (84.7 ± 27.8% maximal voluntary isometric contractions, MVIC) compared with BWS (20.4 ± 3.4 kg, 63.4 ± 21.6% MVIC). No difference in rectus abdominis or erector spinae sEMG was detected between exercise modes. Isometric force decrement was greater during BWS (-21.7 ± 7.0 kg) compared with BB (-14.9 ± 4.7 kg); however, BB (-3.0 ± 0.8 kg/set) resulted in a steeper decline in ROF compared with BWS (-1.7 ± 0.6 kg/set). The variable resistance loading and greater isometric force decrement observed suggest that select BWS exercises may resemble variable resistance exercise more than previously considered.

  3. Propranolol and atropine do not alter choroidal blood flow regulation during isometric exercise in healthy humans.

    PubMed

    Polska, Elzbieta; Luksch, Alexandra; Schering, Joanne; Frank, Barbara; Imhof, Andrea; Fuchsjäger-Mayrl, Gabriele; Wolzt, Michael; Schmetterer, Leopold

    2003-01-01

    Recent studies indicate that the human choroid has a considerable capacity to keep blood flow constant despite exercise-induced increases in perfusion pressure. The mechanisms underlying this vasoconstrictor response remain unclear. We hypothesized that pharmacological modulation of the autonomic nervous system may alter the choroidal pressure/flow relationship during squatting. To test this hypothesis, we performed a randomized, double-masked, placebo-controlled, three-way crossover study in 15 healthy male volunteers. Subjects received, on different study days, intravenous infusions of the beta-adrenoceptor antagonist propranolol, the muscarinic receptor antagonist atropine, or placebo. During these infusions, subjects performed squatting for 6 min. Choroidal blood flow was assessed with laser Doppler flowmetry and ocular perfusion pressure (OPP) was calculated from mean arterial pressure and intraocular pressure. As expected, propranolol reduced basal pulse rate, whereas atropine increased pulse rate, indicating that the drugs were administered at systemically effective doses. None of the drugs altered the choroidal pressure/flow relationship during isometric exercise. These data indicate that the regulatory vasoconstrictor capacity of the choroid during exercise is not affected by systemic blockade of beta-adrenoceptors or muscarinic receptors.

  4. Smoking before isometric exercise amplifies myocardial stress and dysregulates baroreceptor sensitivity and cerebral oxygenation.

    PubMed

    Anyfanti, Panagiota; Triantafyllidou, Eleftheria; Papadopoulos, Stavros; Triantafyllou, Areti; Nikolaidis, Michalis G; Kyparos, Antonios; Vrabas, Ioannis S; Douma, Stella; Zafeiridis, Andreas; Dipla, Konstantina

    2017-06-01

    This crossover study examined whether acute cardiovascular responses, baroreceptor sensitivity (BRS), and brain oxygenation during isometric exercise are altered after cigarette smoking. Twelve young, habitual smokers randomly performed a smoking and a control protocol, during which participants smoked one cigarette (0.9 mg nicotine) or a sham cigarette, before exercise. Testing involved baseline, a 5-minute smoking, a 10-minute post-smoking rest, 3-minute handgrip exercise (30% maximum voluntary contraction), and recovery. Beat-to-beat blood pressure, heart rate (HR), and cerebral oxygenation (near infrared spectroscopy) were continuously monitored. Double-product, stroke volume (SV), cardiac output, systemic vascular resistance and BRS were assessed. During post-smoking rest, systolic or diastolic blood pressure (140.8 ± 12.1/87.0 ± 6.9 vs. 125.9 ± 7.1/77.3 ± 5.5 mm Hg), HR, and double product were higher in the smoking versus the control protocol, whereas BRS was lower (P < .05). During handgrip exercise, smoking resulted in greater HR and double product (17,240 ± 3893 vs. 15,424 ± 3173 mm Hg·bpm) and lower BRS versus the control protocol (P < .05), without significant differences in stroke volume and systemic vascular resistance between protocols. During recovery, smoking elicited a delayed return of brain oxygenation indices, lower BRS, and higher double product. Smoking a cigarette shortly before the exercise session amplifies myocardial stress and dysregulates autonomic function and cerebral oxygenation during exercise and recovery, even in young habitual smokers, perceived as free from long-term cardiovascular effects of smoking. Copyright © 2017 American Society of Hypertension. Published by Elsevier Inc. All rights reserved.

  5. Exercise training improves hemodynamic recovery to isometric exercise in obese men with type 2 diabetes but not in obese women.

    PubMed

    Kanaley, Jill A; Goulopoulou, Styliani; Franklin, Ruth; Baynard, Tracy; Carhart, Robert L; Weinstock, Ruth S; Fernhall, Bo

    2012-12-01

    Women with type 2 diabetes (T2D) show greater rates of mortality due to ischemic heart disease than men with T2D. We aimed to examine cardiovascular and autonomic function responses to isometric handgrip (IHG) exercise between men and women with T2D, before and after an exercise training program. Hemodynamic responses were measured in 22 men and women with T2D during and following a 3-min IHG test, and before and after 16 wks of aerobic exercise training. Women had a smaller decrease in mean arterial pressure (MAP) and systolic blood pressure (BP) during recovery from IHG (ΔMAP(REC)) than men pre- and post-training (P<0.05). Men showed a greater reduction in diastolic BP during recovery from IHG (P<0.05), and exercise training improved this response in men but not in women (men, pre-training: -13.9±1.8, post-training: -20.5±5.3 mmHg vs. women, pre-training: -10.7±1.7, post-training: -4.1±4.9 mmHg; P<0.05). Men had a greater reduction in sympathetic modulation of vasomotor tone (P<0.05), as estimated by blood pressure variability, following IHG. This response was accentuated after training, while this training effect was not seen in women. Post-training ΔMAP(REC) was correlated with recovery of low frequency component of the BP spectrum (ΔLF(SBPrec), r=0.52, P<0.05). Differences in BP recovery immediately following IHG may be attributed to gender differences in cardiovascular autonomic modulation. An improvement in these responses occurs following aerobic exercise training in obese men, but not in obese women with T2D which reflects a better adaptive autonomic response to exercise training. Copyright © 2012 Elsevier Inc. All rights reserved.

  6. Effects of adding whole body vibration to squat training on isometric force/time characteristics.

    PubMed

    Lamont, Hugh S; Cramer, Joel T; Bemben, Debra A; Shehab, Randa L; Anderson, Mark A; Bemben, Michael G

    2010-01-01

    Resistance training interventions aimed at increasing lower-body power and rates of force development have produced varying results. Recent studies have suggested that whole-body low-frequency vibration (WBLFV) may elicit an acute postactivation potentiation response, leading to acute improvements in power and force development. Potentially, the use of WBLFV between sets of resistance training rather than during training itself may lead to increased recruitment and synchronization of high-threshold motor units, minimize fatigue potential, and facilitate the chronic adaptation to resistance exercise. The purpose of this study was to determine the effects of applying TriPlaner, WBLFV, prior to and then intermittently between sets of Smith machine squats on short-term adaptations in explosive isometric force expression. Thirty recreationally resistance trained men aged 18-30 were randomly assigned to 1 of 3 groups: resistance training only (SQT, n = 11), resistance plus whole-body vibration (SQTV, n = 13), or active control (CON, n = 6). An isometric squat test was performed prior to and following a 6-week periodized Smith machine squat program. Whole-body low-frequency vibration was applied 180 seconds prior to the first work set (50 Hz, 2-4 mm, 30 seconds) and intermittently (50 Hz, 4-6 mm, 3 x 10 seconds, 60 seconds between exposures) within a 240-second interset rest period. Subjects were instructed to assume a quarter squat posture while positioning their feet directly under their center of mass, which was modified using a handheld goniometer to a knee angle of 135 +/- 5 degrees . Instructions were given to subjects to apply force as fast and as hard as possible for 3.5 seconds. Isometric force (N) and rates of force development (N.s(-1)) were recorded from the onset of contraction (F(0)) to time points corresponding to 30, 50, 80, 100, 150, and 250 milliseconds, as well as the peak isometric rate of force development (PISORFD), and rate of force development to

  7. A comparison of isometric, isotonic concentric and isotonic eccentric exercises in the physiotherapy management of subacromial pain syndrome/rotator cuff tendinopathy: study protocol for a pilot randomised controlled trial.

    PubMed

    Kinsella, Rita; Cowan, Sallie M; Watson, Lyn; Pizzari, Tania

    2017-01-01

    Subacromial pain syndrome (SPS) involving rotator cuff tendinopathy is a common cause of shoulder pain and disability. Evidence suggests that structured physiotherapy may be as effective as surgery in this condition with significant improvements demonstrated in trials involving scapular retraining, rotator cuff strengthening and flexibility exercises. Most published programs typically utilise isotonic concentric and/or eccentric strengthening modes. Recently, immediate analgesic effects and muscle strength gains following heavy-load isometric exercises in lower limb tendinopathy conditions have been observed. It is pertinent to ascertain whether such outcomes can be replicated in SPS/rotator cuff tendinopathy. The primary aim of this study is to establish the feasibility of undertaking a full-scale randomised controlled trial (RCT) that compares the effects of isometric, isotonic concentric and isotonic eccentric rotator cuff contractions when used as part of a semi-standardised exercise-based physiotherapy program in patients diagnosed with SPS. The secondary aim is to explore potential trends or treatment effects of the exercise intervention. Thirty-six participants diagnosed with SPS will be randomised to one of three intervention groups and undergo a one-on-one exercise-based physiotherapy intervention, involving scapular and rotator cuff muscle retraining and strengthening. Each group will utilise a different mode of rotator cuff strengthening-isometric, isotonic concentric or isotonic eccentric. Rotator cuff tendon responses to isometric loading are not yet established in the literature; hence, individualised, progressive loading will be used in this pilot study in accordance with symptoms. The intervention will involve two phases: during Phase 1 (weeks 1-6) participants undertake the active group-specific physiotherapy treatment; in Phase 2 (weeks 6-12), they undertake a progressive, but no longer group-specific exercise program. To determine feasibility, an

  8. Effects of plyometric and isometric training on muscle and tendon stiffness in vivo.

    PubMed

    Kubo, Keitaro; Ishigaki, Tomonobu; Ikebukuro, Toshihiro

    2017-08-01

    The purpose of this study was to compare the effects of plyometric and isometric training on tendon properties during ramp and ballistic contractions and muscle stiffness under passive and active conditions. Eleven subjects completed 12 weeks (3 days/week) of a unilateral training program for the plantar flexors. They performed plyometric training on one side (PLY) and isometric training on the other side (ISO). Active muscle stiffness in the medial gastrocnemius muscle was calculated according to changes in estimated muscle force and fascicle length during fast stretching after submaximal isometric contractions. Passive muscle stiffness was also calculated from estimated passive muscle force and fascicle length during slow passive stretching. Stiffness and hysteresis of tendon structures were measured using ultrasonography during ramp and ballistic contractions. Passive muscle stiffness and tendon hysteresis did not change for PLY or ISO Active muscle stiffness significantly increased for PLY, but not for ISO Tendon stiffness during ramp and ballistic contractions increased significantly for ISO, but not for PLY In addition, tendon elongation values at force production levels beyond 100 N during ballistic contractions increased for PLY These results suggest that plyometric training (but not isometric training) enhances the extensibility of tendon structures during ballistic contractions and active muscle stiffness during fast stretching, and these changes may be related to improved performances during stretch-shortening cycle exercises. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

  9. The Effects of Exercise on the Firing Patterns of Single Motor Units.

    ERIC Educational Resources Information Center

    Cracraft, Joe D.

    In this study, the training effects of static and dynamic exercise programs on the firing patterns of 450 single motor units (SMU) in the human tibialis anterior muscle were investigated. In a six week program, the static group (N=5) participated in daily high intensity, short duration, isometric exercises while the dynamic group (N=5)…

  10. Sex Differences in Cardiac Baroreflex Sensitivity after Isometric Handgrip Exercise.

    PubMed

    Teixeira, André L; Ritti-Dias, Raphael; Antonino, Diego; Bottaro, Martim; Millar, Philip J; Vianna, Lauro C

    2018-04-01

    This study aimed to investigate potential sex-related differences on spontaneous cardiac baroreflex sensitivity (cBRS) after acute isometric handgrip (IHG) exercise. Twenty men (age, 23 ± 3 yr) and 20 women (age, 24 ± 4 yr) randomly performed four sets of 2-min IHG exercise (two sets for each limb) at 30% maximal voluntary contraction (experimental) or 3% maximal voluntary contraction (sham). Beat-to-beat heart rate (HR) and arterial blood pressure (BP) were monitored using finger photoplethysmography before and 10, 20, and 30 min after IHG. Spontaneous cBRS was assessed via the sequence technique and cardiac autonomic modulation via time- and frequency-domain HR variability. After IHG, spontaneous cBRS increased during 10 min of recovery in men (Δ13% ± 5%, P = 0.03 vs rest) and increased further in women (Δ23% ± 4%, P < 0.01 vs rest; P = 0.04 vs men). During 20 and 30 min of recovery, cBRS returned to baseline in men but remained elevated in women. HR decreased 10 min after IHG in men (10 min: Δ-2 ± 1 bpm, P < 0.01 vs rest; 20 min: Δ-1 ± 1 bpm, P = 0.39 vs rest; 30 min: Δ1 ± 1 bpm, P = 0.31 vs rest) and throughout recovery in women (10 min: Δ-5 ± 1 bpm, P < 0.01 vs rest; 20 min: Δ-3 ± 1 bpm, P < 0.01 vs rest; 30 min: Δ-2 ± 1 bpm, P < 0.01 vs rest). Systolic BP increased 10 min after IHG and remained elevated during 20 min and 30 min in men (P < 0.05). In women, systolic BP increased during 10 min (P < 0.01) and returned to baseline during 20 and 30 min of recovery. Time-domain HR variability (root mean square of successive differences) was increased during recovery in men and women (P < 0.05). Sham had no effect on any variables. Acute IHG exercise increases cBRS and cardiac vagal activity in healthy young subjects, but the magnitude and the time course of changes in cBRS differ between men and women.

  11. Fractal based complexity measure and variation in force during sustained isometric muscle contraction: effect of aging.

    PubMed

    Arjunan, Sridhar P; Kumar, Dinesh K; Bastos, Teodiano

    2012-01-01

    This study has investigated the effect of age on the fractal based complexity measure of muscle activity and variance in the force of isometric muscle contraction. Surface electromyogram (sEMG) and force of muscle contraction were recorded from 40 healthy subjects categorized into: Group 1: Young - age range 20-30; 10 Males and 10 Females, Group 2: Old - age range 55-70; 10 Males and 10 Females during isometric exercise at Maximum Voluntary contraction (MVC). The results show that there is a reduction in the complexity of surface electromyogram (sEMG) associated with aging. The results demonstrate that there is an increase in the coefficient of variance (CoV) of the force of muscle contraction and a decrease in complexity of sEMG for the Old age group when compared with the Young age group.

  12. Effect of New Zealand blueberry consumption on recovery from eccentric exercise-induced muscle damage

    PubMed Central

    2012-01-01

    Background Exercise-induced muscle damage (EIMD) is accompanied by localized oxidative stress / inflammation which, in the short-term at least, is associated with impaired muscular performance. Dietary antioxidants have been shown to reduce excessive oxidative stress; however, their effectiveness in facilitating recovery following EIMD is not clear. Blueberries demonstrate antioxidant and anti-inflammatory properties. In this study we examine the effect of New Zealand blueberries on EIMD after strenuous eccentric exercise. Methods In a randomized cross-over design, 10 females consumed a blueberry smoothie or placebo of a similar antioxidant capacity 5 and 10 hours prior to and then immediately, 12 and 36 hours after EIMD induced by 300 strenuous eccentric contractions of the quadriceps. Absolute peak and average peak torque across the knee, during concentric, isometric, and eccentric actions were measured. Blood biomarkers of oxidative stress, antioxidant capacity, and inflammation were assessed at 12, 36 and 60 hours post exercise. Data were analyzed using a two-way ANOVA. Results A significant (p < 0.001) decrease in isometric, concentric and eccentric torque was observed 12 hours following exercise in both treatment groups. During the 60 hour recovery period, a significant (p = 0.047) interaction effect was seen for peak isometric tension suggesting a faster rate of recovery in the blueberry intervention group. A similar trend was observed for concentric and eccentric strength. An increase in oxidative stress and inflammatory biomarkers was also observed in both treatment groups following EIMD. Although a faster rate of decrease in oxidative stress was observed in the blueberry group, it was not significant (p < 0.05) until 36 hours post-exercise and interestingly coincided with a gradual increase in plasma antioxidant capacity, whereas biomarkers for inflammation were still elevated after 60 hours recovery. Conclusions This study demonstrates that

  13. Effect of New Zealand blueberry consumption on recovery from eccentric exercise-induced muscle damage.

    PubMed

    McLeay, Yanita; Barnes, Matthew J; Mundel, Toby; Hurst, Suzanne M; Hurst, Roger D; Stannard, Stephen R

    2012-07-11

    Exercise-induced muscle damage (EIMD) is accompanied by localized oxidative stress / inflammation which, in the short-term at least, is associated with impaired muscular performance. Dietary antioxidants have been shown to reduce excessive oxidative stress; however, their effectiveness in facilitating recovery following EIMD is not clear. Blueberries demonstrate antioxidant and anti-inflammatory properties. In this study we examine the effect of New Zealand blueberries on EIMD after strenuous eccentric exercise. In a randomized cross-over design, 10 females consumed a blueberry smoothie or placebo of a similar antioxidant capacity 5 and 10 hours prior to and then immediately, 12 and 36 hours after EIMD induced by 300 strenuous eccentric contractions of the quadriceps. Absolute peak and average peak torque across the knee, during concentric, isometric, and eccentric actions were measured. Blood biomarkers of oxidative stress, antioxidant capacity, and inflammation were assessed at 12, 36 and 60 hours post exercise. Data were analyzed using a two-way ANOVA. A significant (p < 0.001) decrease in isometric, concentric and eccentric torque was observed 12 hours following exercise in both treatment groups. During the 60 hour recovery period, a significant (p = 0.047) interaction effect was seen for peak isometric tension suggesting a faster rate of recovery in the blueberry intervention group. A similar trend was observed for concentric and eccentric strength. An increase in oxidative stress and inflammatory biomarkers was also observed in both treatment groups following EIMD. Although a faster rate of decrease in oxidative stress was observed in the blueberry group, it was not significant (p < 0.05) until 36 hours post-exercise and interestingly coincided with a gradual increase in plasma antioxidant capacity, whereas biomarkers for inflammation were still elevated after 60 hours recovery. This study demonstrates that the ingestion of a blueberry smoothie

  14. Comparison of exercises inducing maximum voluntary isometric contraction for the latissimus dorsi using surface electromyography.

    PubMed

    Park, Se-yeon; Yoo, Won-gyu

    2013-10-01

    The aim of this study was to compare muscular activation during five different normalization techniques that induced maximal isometric contraction of the latissimus dorsi. Sixteen healthy men participated in the study. Each participant performed three repetitions each of five types of isometric exertion: (1) conventional shoulder extension in the prone position, (2) caudal shoulder depression in the prone position, (3) body lifting with shoulder depression in the seated position, (4) trunk bending to the right in the lateral decubitus position, and (5) downward bar pulling in the seated position. In most participants, maximal activation of the latissimus dorsi was observed during conventional shoulder extension in the prone position; the percentage of maximal voluntary contraction was significantly greater for this exercise than for all other normalization techniques except downward bar pulling in the seated position. Although differences in electrode placement among various electromyographic studies represent a limitation, normalization techniques for the latissimus dorsi are recommended to minimize error in assessing maximal muscular activation of the latissimus dorsi through the combined use of shoulder extension in the prone position and downward pulling. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. Relationship between isometric and dynamic strength in recreationally trained men.

    PubMed

    McGuigan, Michael R; Newton, Michael J; Winchester, Jason B; Nelson, Arnold G

    2010-09-01

    The purpose of this investigation was to examine the relationships between measures of maximal isometric force (peak force [PF]), rate of force development (RFD), vertical jump performance (VJ) and 1-repetition maximum (1RM) strength in recreationally trained men. The subjects in this study were 26 men ([mean +/- SD]: age 22 +/- 1 years; height 175 +/- 7 cm; mass 90 +/- 10 kg). They were tested for PF using the isometric midthigh pull exercise. The 1RM for the squat and bench press exercise were determined as a measure of dynamic strength. Explosive strength was measured as RFD from the isometric force-time curve. Correlations between the variables were calculated using Pearson product moment correlation coefficient. There was a nearly perfect correlation between measures of PF and 1RM squat (r = 0.97, p < 0.05) and 1RM bench press (r = 0.99, p < 0.05). The correlations were very strong between VJ and PF (r = 0.72, p < 0.05) and 1RM bench press (r = 0.70, p < 0.05). There were also strong correlations between VJ and 1RM squat (r = 0.69, p < 0.05). There were no significant correlations with RFD. The results showed that isometric maximum strength determined during the isometric midthigh pull test correlated well with 1RM and VJ testing. However, RFD measured during the same test did not appear to correlate as well with other measures. The isometric midthigh pull provides an efficient method for assessing strength in recreationally trained individuals. Practitioners wishing to obtain performance data related to maximum strength may wish to consider isometric testing as a less time intensive method of testing.

  16. Acute effects of dynamic exercises on the relationship between the motor unit firing rate and the recruitment threshold.

    PubMed

    Ye, Xin; Beck, Travis W; DeFreitas, Jason M; Wages, Nathan P

    2015-04-01

    The aim of this study was to compare the acute effects of concentric versus eccentric exercise on motor control strategies. Fifteen men performed six sets of 10 repetitions of maximal concentric exercises or eccentric isokinetic exercises with their dominant elbow flexors on separate experimental visits. Before and after the exercise, maximal strength testing and submaximal trapezoid isometric contractions (40% of the maximal force) were performed. Both exercise conditions caused significant strength loss in the elbow flexors, but the loss was greater following the eccentric exercise (t=2.401, P=.031). The surface electromyographic signals obtained from the submaximal trapezoid isometric contractions were decomposed into individual motor unit action potential trains. For each submaximal trapezoid isometric contraction, the relationship between the average motor unit firing rate and the recruitment threshold was examined using linear regression analysis. In contrast to the concentric exercise, which did not cause significant changes in the mean linear slope coefficient and y-intercept of the linear regression line, the eccentric exercise resulted in a lower mean linear slope and an increased mean y-intercept, thereby indicating that increasing the firing rates of low-threshold motor units may be more important than recruiting high-threshold motor units to compensate for eccentric exercise-induced strength loss. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Impact of Hypertension on Ventricular-Arterial Coupling and Regional Myocardial Work at Rest and during Isometric Exercise

    PubMed Central

    Kuznetsova, Tatiana; D’hooge, Jan; Kloch-Badelek, Malgorzata; Sakiewicz, Wojciech; Thijs, Lutgarde; Staessen, Jan A.

    2013-01-01

    Background To understand better the mechanism of left ventricular (LV) remodeling related to hypertension, it is important to evaluate LV function in relation to the changes in loading conditions. The aim of this study was to investigate changes in conventional ventricular-arterial coupling indexes, LV strain, and a new index reflecting regional myocardial work assessed noninvasively at rest and during isometric exercise in a random sample including participants with normal blood pressure and those with hypertension. Methods A total of 148 participants (53.4% women; mean age, 52.0 years; 39.2% with hypertension) underwent simultaneous echocardiographic and arterial data acquisition at rest and during increased afterload (handgrip exercise). End-systolic pressure was determined from the carotid pulse wave. Arterial elastance (Ea) and LV elastance (Ees) were calculated as end-systolic pressure/stroke volume and end-systolic pressure/end-systolic volume. Doppler tissue imaging and two-dimensional speckle tracking were used to derive LV longitudinal strain. Regional myocardial work (ejection work density [EWD]) was the area of the pressure-strain loop during ejection. Results At rest, with adjustments applied, Ees (3.06 vs 3.71 mmHg/mL,P = .0003), Ea/Ees (0.54 vs 0.47,P=.002) and EWD (670 vs 802 Pa/m2, P = .0001) differed significantly between participants with normal blood pressure and those with hypertension. During handgrip exercise, Ea and Ea/Ees significantly increased (P < .0001) in both groups. Doppler tissue imaging and two-dimensional LV strain decreased in participants with hypertension (P ≤ .008). Only in subjects with normal blood pressure EWD significantly increased (+14.7%, P = .0009). Conclusions Although patients with hypertension compared with those with normal blood pressure have increased LV systolic stiffness and regional myocardial work to match arterial load at rest, they might have diminished cardiac reserve to increase myocardial performance

  18. Effect of exercise on the pseudodiabetes of bed rest

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.

    1982-01-01

    The effect of intensive isotonic exercise and isometric exercise (with its low metabolic rate) during bed rest on plasma insulin and glucose tolerance test was investigated. The subjects were seven healthy men, 19 to 22 years in age, 166 to 188 cm in height, and 62.40 to 103.80 kg in weight; maximal oxygen uptakes ranged from 3.36 to 4.38 liters/min. It appears that bed-rest-induced glucose intolerance is diminished with increasing energy expenditure during both bed rest and recovery.

  19. Evaluation of the numeric rating scale for perception of effort during isometric elbow flexion exercise.

    PubMed

    Lampropoulou, Sofia; Nowicky, Alexander V

    2012-03-01

    The aim of the study was to examine the reliability and validity of the numerical rating scale (0-10 NRS) for rating perception of effort during isometric elbow flexion in healthy people. 33 individuals (32 ± 8 years) participated in the study. Three re-test measurements within one session and three weekly sessions were undertaken to determine the reliability of the scale. The sensitivity of the scale following 10 min isometric fatiguing exercise of the elbow flexors as well as the correlation of the effort with the electromyographic (EMG) activity of the flexor muscles were tested. Perception of effort was tested during isometric elbow flexion at 10, 30, 50, 70, 90, and 100% MVC. The 0-10 NRS demonstrated an excellent test-retest reliability [intra class correlation (ICC) = 0.99 between measurements taken within a session and 0.96 between 3 consecutive weekly sessions]. Exploratory curve fitting for the relationship between effort ratings and voluntary force, and underlying EMG showed that both are best described by power functions (y = ax ( b )). There were also strong correlations (range 0.89-0.95) between effort ratings and EMG recordings of all flexor muscles supporting the concurrent criterion validity of the measure. The 0-10 NRS was sensitive enough to detect changes in the perceived effort following fatigue and significantly increased at the level of voluntary contraction used in its assessment (p < 0.001). These findings suggest the 0-10 NRS is a valid and reliable scale for rating perception of effort in healthy individuals. Future research should seek to establish the validity of the 0-10 NRS in clinical settings.

  20. Exercise increases pressure pain tolerance but not pressure and heat pain thresholds in healthy young men.

    PubMed

    Vaegter, H B; Hoeger Bement, M; Madsen, A B; Fridriksson, J; Dasa, M; Graven-Nielsen, T

    2017-01-01

    Exercise causes an acute decrease in the pain sensitivity known as exercise-induced hypoalgesia (EIH), but the specificity to certain pain modalities remains unknown. This study aimed to compare the effect of isometric exercise on the heat and pressure pain sensitivity. On three different days, 20 healthy young men performed two submaximal isometric knee extensions (30% maximal voluntary contraction in 3 min) and a control condition (quiet rest). Before and immediately after exercise and rest, the sensitivity to heat pain and pressure pain was assessed in randomized and counterbalanced order. Cuff pressure pain threshold (cPPT) and pain tolerance (cPTT) were assessed on the ipsilateral lower leg by computer-controlled cuff algometry. Heat pain threshold (HPT) was recorded on the ipsilateral foot by a computer-controlled thermal stimulator. Cuff pressure pain tolerance was significantly increased after exercise compared with baseline and rest (p < 0.05). Compared with rest, cPPT and HPT were not significantly increased by exercise. No significant correlation between exercise-induced changes in HPT and cPPT was found. Test-retest reliability before and after the rest condition was better for cPPT and CPTT (intraclass correlation > 0.77) compared with HPT (intraclass correlation = 0.54). The results indicate that hypoalgesia after submaximal isometric exercise is primarily affecting tolerance of pressure pain compared with the pain threshold. These data contribute to the understanding of how isometric exercise influences pain perception, which is necessary to optimize the clinical utility of exercise in management of chronic pain. The effect of isometric exercise on pain tolerance may be relevant for patients in chronic musculoskeletal pain as a pain-coping strategy. WHAT DOES THIS STUDY ADD?: The results indicate that hypoalgesia after submaximal isometric exercise is primarily affecting tolerance of pressure pain compared with the heat and pressure pain

  1. Activation of selected shoulder muscles during unilateral wall and bench press tasks under submaximal isometric effort.

    PubMed

    Tucci, Helga T; Ciol, Marcia A; de Araújo, Rodrigo C; de Andrade, Rodrigo; Martins, Jaqueline; McQuade, Kevin J; Oliveira, Anamaria S

    2011-07-01

    Controlled laboratory study. To assess the activation of 7 shoulder muscles under 2 closed kinetic chain (CKC) tasks for the upper extremity using submaximal isometric effort, thus providing relative quantification of muscular isometric effort for these muscles across the CKC exercises, which may be applied to rehabilitation protocols for individuals with shoulder weakness. CKC exercises favor joint congruence, reduce shear load, and promote joint dynamic stability. Additionally, knowledge about glenohumeral and periscapular muscle activity elicited during CKC exercises may help clinicians to design protocols for shoulder rehabilitation. Using surface electromyography, activation level was measured across 7 shoulder muscles in 20 healthy males, during the performance of a submaximal isometric wall press and bench press. Signals were normalized to the maximal voluntary isometric contraction, and, using paired t tests, data were analyzed between the exercises for each muscle. Compared to the wall press, the bench press elicited higher activity for most muscles, except for the upper trapezius. Levels of activity were usually low but were above 20% maximal voluntary isometric contraction for the serratus anterior on both tasks, and for the long head triceps brachii on the bench press. Both the bench press and wall press, as performed in this study, led to relatively low EMG activation levels for the muscles measured and may be considered for use in the early phases of rehabilitation.

  2. Differences in muscle sympathetic nerve response to isometric exercise in different muscle groups.

    PubMed

    Saito, M

    1995-01-01

    The aim of this study was to examine the effects of muscle fibre composition on muscle sympathetic nerve activity (MSNA) in response to isometric exercise. The MSNA, recorded from the tibial nerve by a microneurographic technique during contraction and following arterial occlusion, was compared in three different muscle groups: the forearm (handgrip), anterior tibialis (foot dorsal contraction), and soleus muscles (foot plantar contraction) contracted separately at intensities of 20%, 33% and 50% of the maximal voluntary force. The increases in MSNA relative to control levels during contraction and occlusion were significant at all contracting forces for handgrip and at 33% and 50% of maximal for dorsal contraction, but there were no significant changes, except during exercise at 50%, for plantar contraction. The size of the MSNA response correlated with the contraction force in all muscle groups. Pooling data for all contraction forces, there were different MSNA responses among muscle groups in contraction forces (P = 0.0001, two-way analysis of variance), and occlusion periods (P = 0.0001). The MSNA increases were in the following order of magnitude: handgrip, dorsal, and plantar contractions. The order of the fibre type composition in these three muscles is from equal numbers of types I and II fibres in the forearm to increasing number of type I fibres in the leg muscles. The different MSNA responses to the contraction of different muscle groups observed may have been due in part to muscle metaboreflex intensity influenced by their metabolic capacity which is related to by their metabolic capacity which is related to the fibre type.

  3. Association Between Maximal Bench Press Strength and Isometric Handgrip Strength Among Breast Cancer Survivors.

    PubMed

    Rogers, Benjamin H; Brown, Justin C; Gater, David R; Schmitz, Kathryn H

    2017-02-01

    To characterize the relationship between 1-repetition maximum (1-RM) bench press strength and isometric handgrip strength among breast cancer survivors. Cross-sectional study. Laboratory. Community-dwelling breast cancer survivors (N=295). Not applicable. 1-RM bench press strength was measured with a barbell and exercise bench. Isometric handgrip strength was measured using an isometric dynamometer, with 3 maximal contractions of the left and right hands. All measures were conducted by staff with training in clinical exercise testing. Among 295 breast cancer survivors, 1-RM bench press strength was 18.2±6.1kg (range, 2.2-43.0kg), and isometric handgrip strength was 23.5±5.8kg (range, 9.0-43.0kg). The strongest correlate of 1-RM bench press strength was the average isometric handgrip strength of both hands (r=.399; P<.0001). Mean difference analysis suggested that the average isometric handgrip strength of both hands overestimated 1-RM bench press strength by 4.7kg (95% limits of agreement, -8.2 to 17.6kg). In a multivariable linear regression model, the average isometric handgrip strength of both hands (β=.31; P<.0001) and age (β=-.20; P<.0001) were positively correlated with 1-RM bench press strength (R 2 =.23). Isometric handgrip strength is a poor surrogate for 1-RM bench press strength among breast cancer survivors. 1-RM bench press strength and isometric handgrip strength quantify distinct components of muscular strength. Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  4. Acute effect of whole body vibration on isometric strength, squat jump, and flexibility in well-trained combat athletes.

    PubMed

    Kurt, C; Pekünlü, E

    2015-06-01

    The purpose of this study was to investigate the effect of whole body vibration (WBV) training on maximal strength, squat jump, and flexibility of well-trained combat athletes. Twelve female and 8 male combat athletes (age: 22.8 ± 3.1 years, mass: 65.4 ± 10.7 kg, height: 168.8 ± 8.8 cm, training experience: 11.6 ± 4.7 years, training volume: 9.3 ± 2.8 hours/week) participated in this study. The study consisted of three sessions separated by 48 hours. The first session was conducted for familiarization. In the subsequent two sessions, participants performed WBV or sham intervention in a randomized, balanced order. During WBV intervention, four isometric exercises were performed (26 Hz, 4 mm). During the sham intervention, participants performed the same WBV intervention without vibration treatment (0 Hz, 0 mm). Hand grip, squat jump, trunk flexion, and isometric leg strength tests were performed after each intervention. The results of a two-factor (pre-post[2] × intervention[2]) repeated measures ANOVA revealed a significant interaction (p = 0.018) of pre-post × intervention only for the hand grip test, indicating a significant performance increase of moderate effect (net increase of 2.48%, d = 0.61) after WBV intervention. Squat jump, trunk flexion, and isometric leg strength performances were not affected by WBV. In conclusion, the WBV protocol used in this study potentiated hand grip performance, but did not enhance squat jump, trunk flexion, or isometric leg strength in well-trained combat athletes.

  5. Validation and Reliability of a Novel Test of Upper Body Isometric Strength.

    PubMed

    Bellar, David; Marcus, Lena; Judge, Lawrence W

    2015-09-29

    The purpose of the present investigation was to examine the association of a novel test of upper body isometric strength against a 1RM bench press measurement. Forty college age adults (n = 20 female, n = 20 male; age 22.8 ± 2.8 years; body height 171.6 ± 10.8 cm; body mass 73.5 ± 16.3 kg; body fat 23.1 ± 5.4%) volunteered for the present investigation. The participants reported to the lab on three occasions. The first visit included anthropometric measurements and familiarization with both the upper body isometric test and bench press exercise. The final visits were conducted in a randomized order, with one being a 1RM assessment on the bench press and the other consisting of three trials of the upper body isometric assessment. For the isometric test, participants were positioned in a "push-up" style position while tethered (stainless steel chain) to a load cell (high frequency) anchored to the ground. The peak isometric force was consistent across all three trials (ICC = 0.98) suggesting good reliability. Multiple regression analysis was completed with the predictors: peak isometric force, gender, against the outcome variable 1RM bench press. The analysis resulted in a significant model (r2 = 0.861, p≤0.001) with all predictor variables attaining significance in the model (p<0.05). Isometric peak strength had the greatest effect on the model (Beta = 5.19, p≤0.001). Results from this study suggest that the described isometric upper body strength assessment is likely a valid and reliable tool to determine strength. Further research is warranted to gather a larger pool of data in regard to this assessment.

  6. Plasma lactic dehydrogenase activities in men during bed rest with exercise training

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Juhos, L. T.; Young, H. L.

    1985-01-01

    Peak oxygen uptake and the activity of lactic dehydrogenase (LDH-T) and its five isoenzymes were measured by spectrophotometer in seven men before, during, and after bed rest and exercise training. Exercise training consisted of isometric leg exercises of 250 kcal/hr for a period of one hour per day. It is found that LDH-T was reduced by 0.05 percent in all three regimens by day 10 of bed rest, and that the decrease occurred at different rates. The earliest reduction in LDH-T activity in the no-exercise regimen was associated with a decrease in peak oxygen uptake of 12.3 percent. It is concluded that isometric (aerobic) muscular strength training appear to maintain skeletal muscle integrity better during bed rest than isotonic exercise training. Reduced hydrostatic pressure during bed rest, however, ultimately counteracts the effects of both moderate isometric and isotonic exercise training, and may result in decreased LDH-T activity.

  7. The Association between Maximal Bench Press Strength and Isometric Handgrip Strength among Breast Cancer Survivors

    PubMed Central

    Rogers, Benjamin H.; Brown, Justin C.; Gater, David R.; Schmitz, Kathryn H.

    2016-01-01

    Objective One-repetition maximum (1-RM) bench press strength is considered the gold standard to quantify upper-body muscular strength. Isometric handgrip strength is frequently used as a surrogate for 1-RM bench press strength among breast cancer (BrCa) survivors. The relationship between 1-RM bench press strength and isometric handgrip strength, however, has not been characterized among BrCa survivors. Design Cross-sectional study. Setting Laboratory. Participants Community-dwelling BrCa survivors. Interventions Not applicable. Main Outcome Measure 1-RM bench press strength was measured with a barbell and exercise bench. Isometric handgrip strength was measured using an isometric dynamometer with three maximal contractions of left and right hands. All measures were conducted by staff with training in clinical exercise testing. Results Among 295 BrCa survivors, 1-RM bench press strength was 18.2±6.1 kg (range: 2.2-43.0) and isometric handgrip strength was 23.5±5.8 kg (range: 9.0-43.0). The strongest correlate of 1-RM bench press strength was the average isometric handgrip strength of both hands (r=0.399; P<0.0001). Mean-difference analysis suggested that the average isometric handgrip strength of both hands overestimated 1-RM bench press strength by 4.7 kg (95% limits of agreement: −8.2 to 17.6). In a multivariable linear regression model, the average isometric handgrip strength of both hands (β=0.31; P<0.0001) and age (β=−0.20; P<0.0001) were positively correlated with 1-RM bench press strength (R2=0.23). Conclusions Isometric handgrip strength is a poor surrogate for 1-RM bench press strength among BrCa survivors. 1-RM bench press and isometric handgrip strength quantify distinct components of muscular strength. PMID:27543047

  8. Sweating responses to isometric hand-grip exercise and forearm muscle metaboreflex in prepubertal children and elderly.

    PubMed

    Amano, Tatsuro; Kai, Seiko; Nakajima, Michi; Ichinose-Kuwahara, Tomoko; Gerrett, Nicola; Kondo, Narihiko; Inoue, Yoshimitsu

    2017-02-01

    What is the central question of this study? Non-thermal factors (e.g. muscle metaboreflex) contribute to the sweating response during exercise. Although it is well recognized that the sweating responses caused by core temperature elevation in prepubertal children and the elderly are attenuated compared with young adults, it is unknown whether non-thermal sweating is also attenuated in these populations. What is the main finding and its importance? The non-thermal sweating response during isometric hand-grip exercise and isolated muscle metaboreflex were attenuated in prepubertal children compared with young adults in a non-uniform manner over the body, but only during the muscle metaboreflex in the elderly. This may explain the maturation- and ageing-related decline of sweating during exercise. The purpose of the present study was to investigate sweating responses to isometric hand-grip (IH) exercise and muscle metaboreflex in prepubertal children and the elderly. In hot conditions (ambient temperature, 35°C; relative humidity, 45%), 13 healthy young adults, 10 prepubertal children and 10 elderly subjects (aged 20.4 ± 1.2, 11.4 ± 0.5 and 63.5 ± 3.1 years, respectively) repeated a three hand-grip exercise protocol that consisted of 1 min IH exercise at 15, 30 or 45% of maximal voluntary contraction (MVC) followed by 2 min postexercise forearm occlusion. Local sweat rates (SRs) on the forehead, chest, forearm, thigh and palm were continuously measured (ventilated capsule method). The forehead SR in prepubertal children during IH exercise at 45% MVC was significantly lower than that of young adults (0.26 ± 0.22 and 0.08 ± 0.15 mg cm -2  min -1 for young adults and children, respectively; P < 0.05) but not of the elderly at any exercise intensities. The SR on the chest (0.22 ± 0.22 and -0.01 ± 0.05 mg cm -2  min -1 for young adults and children, respectively), forearm (0.14 ± 0.12 and 0.03 ± 0.04 mg cm -2  min -1 ) and thigh (0

  9. Fatigue Analysis Before and After Shaker Exercise: Physiologic Tool for Exercise Design

    PubMed Central

    White, Kevin T.; Easterling, Caryn; Roberts, Niles; Shaker, Reza

    2016-01-01

    Recent studies suggest that the Shaker exercise induces fatigue in the upper esophageal sphincter (UES) opening muscles and sternocleidomastoid (SCM), with the SCMs fatiguing earliest. The aim of this study was to measure fatigue induced by the isometric portion of the Shaker exercise by measuring the rate of change in the median frequency (MF rate) of the power spectral density (PSD) function, which is interpreted as proportional to the rate of fatigue, from surface electromyography (EMG) of suprahyoid (SHM), infrahyoid (IHM), and SCM. EMG data compared fatigue-related changes from 20-, 40-, and 60-s isometric hold durations of the Shaker exercise. We found that fatigue-related changes were manifested during the 20-s hold. The findings confirm that the SCM fatigues initially and as fast as or faster than the SHM and IHM. In addition, upon completion of the exercise protocol, the SCM had a decreased MF rate, implying improved fatigue resistance, while the SHM and IHM showed increased MF rates, implying that these muscles increased their fatiguing effort. We conclude that the Shaker exercise initially leads to increased fatigue resistance of the SCM, after which the exercise loads the less fatigue-resistant SHM and IHM, potentiating the therapeutic effect of the Shaker exercise regimen with continued exercise performance. PMID:18369673

  10. Muscle fiber type-specific response of Hsp70 expression in human quadriceps following acute isometric exercise.

    PubMed

    Tupling, A R; Bombardier, E; Stewart, R D; Vigna, C; Aqui, A E

    2007-12-01

    To investigate the time course of fiber type-specific heat shock protein 70 (Hsp70) expression in human skeletal muscle after acute exercise, 10 untrained male volunteers performed single-legged isometric knee extensor exercise at 60% of their maximal voluntary contraction (MVC) with a 50% duty cycle (5-s contraction and 5-s relaxation) for 30 min. Muscle biopsies were collected from the vastus lateralis before (Pre) exercise in the rested control leg (C) and immediately after exercise (Post) in the exercised leg (E) only and on recovery days 1 (R1), 2 (R2), 3 (R3), and 6 (R6) from both legs. As demonstrated by Western blot analysis, whole muscle Hsp70 content was unchanged (P > 0.05) immediately after exercise (Pre vs. Post), was increased (P < 0.05) by approximately 43% at R1, and remained elevated throughout the entire recovery period in E only. Hsp70 expression was also assessed in individual muscle fiber types I, IIA, and IIAX/IIX by immunohistochemistry. There were no fiber type differences (P > 0.05) in basal Hsp70 expression. Immediately after exercise, Hsp70 expression was increased (P < 0.05) in type I fibers by approximately 87% but was unchanged (P > 0.05) in type II fibers (Pre vs. Post). At R1 and throughout recovery, Hsp70 content in E was increased above basal levels (P < 0.05) in all fiber types, but Hsp70 expression was always highest (P < 0.05) in type I fibers. Hsp70 content in C was not different from Pre at any time throughout recovery. Glycogen depletion was observed at Post in all type II, but not type I, fibers, suggesting that the fiber type differences in exercise-induced Hsp70 expression were not related to glycogen availability. These results demonstrate that the time course of exercise-induced Hsp70 expression in human skeletal muscle is fiber type specific.

  11. Effect of muscle mass and intensity of isometric contraction on heart rate.

    PubMed

    Gálvez, J M; Alonso, J P; Sangrador, L A; Navarro, G

    2000-02-01

    The purpose of this study was to determine the effect of muscle mass and the level of force on the contraction-induced rise in heart rate. We conducted an experimental study in a sample of 28 healthy men between 20 and 30 yr of age (power: 95%, alpha: 5%). Smokers, obese subjects, and those who performed regular physical activity over a certain amount of energetic expenditure were excluded from the study. The participants exerted two types of isometric contractions: handgrip and turning a 40-cm-diameter wheel. Both were sustained to exhaustion at 20 and 50% of maximal force. Twenty-five subjects finished the experiment. Heart rate increased a mean of 15.1 beats/min [95% confidence interval (CI): 5.5-24.6] from 20 to 50% handgrip contractions, and 20.7 beats/min (95% CI: 11.9-29.5) from 20 to 50% wheel-turn contractions. Heart rate also increased a mean of 13.3 beats/min (95% CI: 10.4-16.1) from handgrip to wheel-turn contractions at 20% maximal force, and 18.9 beats/min (95% CI: 9. 8-28.0) from handgrip to wheel-turn contractions at 50% maximal force. We conclude that the magnitude of the heart rate increase during isometric exercise is related to the intensity of the contraction and the mass of the contracted muscle.

  12. Validation and Reliability of a Novel Test of Upper Body Isometric Strength

    PubMed Central

    Bellar, David; Marcus, Lena; Judge, Lawrence W.

    2015-01-01

    The purpose of the present investigation was to examine the association of a novel test of upper body isometric strength against a 1RM bench press measurement. Forty college age adults (n = 20 female, n = 20 male; age 22.8 ± 2.8 years; body height 171.6 ± 10.8 cm; body mass 73.5 ± 16.3 kg; body fat 23.1 ± 5.4%) volunteered for the present investigation. The participants reported to the lab on three occasions. The first visit included anthropometric measurements and familiarization with both the upper body isometric test and bench press exercise. The final visits were conducted in a randomized order, with one being a 1RM assessment on the bench press and the other consisting of three trials of the upper body isometric assessment. For the isometric test, participants were positioned in a “push-up” style position while tethered (stainless steel chain) to a load cell (high frequency) anchored to the ground. The peak isometric force was consistent across all three trials (ICC = 0.98) suggesting good reliability. Multiple regression analysis was completed with the predictors: peak isometric force, gender, against the outcome variable 1RM bench press. The analysis resulted in a significant model (r2 = 0.861, p≤0.001) with all predictor variables attaining significance in the model (p<0.05). Isometric peak strength had the greatest effect on the model (Beta = 5.19, p≤0.001). Results from this study suggest that the described isometric upper body strength assessment is likely a valid and reliable tool to determine strength. Further research is warranted to gather a larger pool of data in regard to this assessment. PMID:26557203

  13. SUSTAINED ISOMETRIC SHOULDER CONTRACTION ON MUSCULAR STRENGTH AND ENDURANCE: A RANDOMIZED CLINICAL TRIAL.

    PubMed

    Myers, Natalie L; Toonstra, Jenny L; Smith, Jacob S; Padgett, Cooper A; Uhl, Tim L

    2015-12-01

    The Advanced Throwers Ten Exercise Program incorporates sustained isometric contractions in conjunction with dynamic shoulder movements. It has been suggested that incorporating isometric holds may facilitate greater increases in muscular strength and endurance. However, no objective evidence currently exists to support this claim. The purpose of this research was to compare the effects of a sustained muscle contraction resistive training program (Advanced Throwers Ten Program) to a more traditional exercise training protocol to determine if increases in shoulder muscular strength and endurance occur in an otherwise healthy population. It was hypothesized that utilizing a sustained isometric hold during a shoulder scaption exercise from the Advanced Throwers Ten would produce greater increases in shoulder strength and endurance as compared to a traditional training program incorporating a isotonic scapular plane abduction (scaption) exercise. Randomized Clinical Trial. Fifty healthy participants were enrolled in this study, of which 25 were randomized into the traditional training group (age: 26 ± 8, height:172 ± 10 cm, weight: 73 ± 13 kg, Marx Activity Scale: 11 ± 4) and 25 were randomized to the Advanced Throwers Ten group (age: 28 ± 9, height: 169 ± 23 cm, weight: 74 ± 16 kg, Marx Activity Scale: 11 ± 5). No pre-intervention differences existed between the groups (P>0.05). Arm endurance and strength data were collected pre and post intervention using a portable load cell (BTE Evaluator, Hanover, MD). Both within and between group analyses were done in order to investigate average torque (strength) and angular impulse (endurance) changes. The traditional and Advanced Throwers Ten groups both significantly improved torque and angular impulse on both the dominant and non-dominant arms by 10-14%. There were no differences in strength or endurance following the interventions between the two training groups (p>0

  14. A Systematic Review of Isometric Lingual Strength-Training Programs in Adults With and Without Dysphagia.

    PubMed

    McKenna, Victoria S; Zhang, Bin; Haines, Morgan B; Kelchner, Lisa N

    2017-05-17

    This systematic review summarizes the effects of isometric lingual strength training on lingual strength and swallow function in adult populations. Furthermore, it evaluates the designs of the reviewed studies and identifies areas of future research in isometric lingual strength training for dysphagia remediation. A comprehensive literature search of 3 databases and additional backward citation search identified 10 studies for inclusion in the review. The review reports and discusses the isometric-exercise intervention protocols, pre- and postintervention lingual-pressure data (maximum peak pressures and lingual-palatal pressures during swallowing), and oropharyngeal swallowing measures such as penetration-aspiration scales, oropharyngeal residue and duration, lingual volumes, and quality-of-life assessments. Studies reported gains in maximum peak lingual pressures following isometric lingual strength training for both healthy adults and select groups of individuals with dysphagia. However, due to the variability in study designs, it remains unclear whether strength gains generalize to swallow function. Although isometric lingual strength training is a promising intervention for oropharyngeal dysphagia, the current literature is too variable to confidently report specific therapeutic benefits. Future investigations should target homogenous patient populations and use randomized controlled trials to determine the efficacy of this treatment for individuals with dysphagia.

  15. Muscle damage and repeated bout effect following blood flow restricted exercise.

    PubMed

    Sieljacks, Peter; Matzon, Andreas; Wernbom, Mathias; Ringgaard, Steffen; Vissing, Kristian; Overgaard, Kristian

    2016-03-01

    Blood-flow restricted resistance exercise training (BFRE) is suggested to be effective in rehabilitation training, but more knowledge is required about its potential muscle damaging effects. Therefore, we investigated muscle-damaging effects of BFRE performed to failure and possible protective effects of previous bouts of BFRE or maximal eccentric exercise (ECC). Seventeen healthy young men were allocated into two groups completing two exercise bouts separated by 14 days. One group performed BFRE in both exercise bouts (BB). The other group performed ECC in the first and BFRE in the second bout. BFRE was performed to failure. Indicators of muscle damage were evaluated before and after exercise. The first bout in the BB group led to decrements in maximum isometric torque, and increases in muscle soreness, muscle water retention, and serum muscle protein concentrations after exercise. These changes were comparable in magnitude and time course to what was observed after first bout ECC. An attenuated response was observed in the repeated exercise bout in both groups. We conclude that unaccustomed single-bout BFRE performed to failure induces significant muscle damage. Additionally, both ECC and BFRE can precondition against muscle damage induced by a subsequent bout of BFRE.

  16. Different weight bearing push-up plus exercises with and without isometric horizontal abduction in subjects with scapular winging: A randomized trial.

    PubMed

    Choi, Woo-Jeong; Yoon, Tae-Lim; Choi, Sil-Ah; Lee, Ji-Hyun; Cynn, Heon-Seock

    2017-07-01

    The aim of the present study was to determine whether the application of isometric horizontal abduction (IHA) differentially affected two weight-bearing push-up plus exercises by examining activation of the scapulothoracic muscles in subjects with scapular winging. Fifteen male subjects performed standard push-up plus (SPP) and wall push-up plus (WPP), with and without IHA. Two-way analyses of variance using two within-subject factors were used to determine the statistical significance of observed differences in upper trapezius (UT), pectoralis major (PM), and serratus anterior (SA) muscle activities and UT/SA and PM/SA muscle activity ratios. UT and SA muscle activities were greater during SPP than WPP. PM muscle activity was lower with IHA application. The UT/SA and PM/SA muscle activity ratios were lower during SPP than WPP. The PM/SA muscle activity ratio was lower with IHA application. The results suggest that IHA application using a Thera-Band can effectively reduce PM muscle activity during SPP and WPP exercises. Moreover, the SPP exercise can be used to increase UT and SA muscle activity and reduce the UT/SA and PM/SA muscle activity ratios in subjects with scapular winging. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Influence of exercise on visceral pain: an explorative study in healthy volunteers

    PubMed Central

    van Weerdenburg, Laura JGM; Brock, Christina; Drewes, Asbjørn Mohr; van Goor, Harry; de Vries, Marjan; Wilder-Smith, Oliver HG

    2017-01-01

    Background and objectives Contradictory results have been found about the effect of different exercise modalities on pain. The aim of this study was to investigate the early effects of aerobic and isometric exercise on different types of experimental pain, including visceral pain, compared to an active control condition. Methods Fifteen healthy subjects (6 women, mean [standard deviation] age 25 [6.5] years) completed 3 interventions consisting of 20 minutes of aerobic cycling, 12 minutes of isometric knee extension and a deep breathing procedure as active control. At baseline and after each intervention, psychophysical tests were performed, including electrical stimulation of the esophagus, pressure pain thresholds and the cold pressor test as a measure for conditioned pain modulation. Participants completed the Medical Outcome Study Short-Form 36 and State-Trait Anxiety Inventory prior to the experiments. Data were analyzed using two-way repeated measures analysis of variance. Results No significant differences were found for the psychophysical tests after the interventions, compared to baseline pain tests and the control condition. Conclusion No hypoalgesic effect of aerobic and isometric exercise was found. The evidence for exercise-induced hypoalgesia appears to be not as consistent as initially thought, and caution is recommended when interpreting the effects of exercise on pain. PMID:28096689

  18. Handgrip and general muscular strength and endurance during prolonged bedrest with isometric and isotonic leg exercise training

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Starr, J. C.; Van Beaumont, W.; Convertino, V. A.

    1983-01-01

    Measurements of maximal grip strength and endurance at 40 percent max strength were obtained for 7 men 19-21 years of age, 1-2 days before and on the first recovery day during three 2-week bedrest (BR) periods, each separated by a 3-week ambulatory recovery period. The subjects performed isometric exercise (IME) for 1 hr/day, isotonic exercise (ITE) for 1 hr/day, and no exercise (NOE) in the three BR periods. It was found that the mean maximal grip strength was unchanged after all three BR periods. Mean grip endurance was found to be unchanged after IME and ITE training, but was significantly reduced after NOE. These results indicate that IME and ITE training during BR do not increase or decrease maximal grip strength, alghough they prevent loss of grip endurance, while the maximal strength of all other major muscle groups decreases in proportion to the length of BR to 70 days. The maximal strength reduction of the large muscle groups was found to be about twice that of the small muscle groups during BR. In addition, it is shown that changes in maximal strength after spaceflight, BR, or water immersion deconditioning cannot be predicted from changes in submaximal or maximal oxygen uptake values.

  19. Effects of whole-body cryotherapy on recovery after hamstring damaging exercise: a crossover study.

    PubMed

    Fonda, B; Sarabon, N

    2013-10-01

    The purpose of this study was to examine the effects of whole-body cryotherapy (WBC) on biochemical, pain, and performance parameters during the 5-day recovery period after damaging exercise for hamstrings. Participants completed a bout of damaging exercise for the hamstring muscles on two separate occasions (control and experimental condition) separated by 10 weeks. During the control condition, subjects received no treatment after the damaging exercise. The experimental condition consisted of WBC everyday during the recovery period. WBC included single 3-min daily exposures to low temperatures (-140 to -19 °C) in the cryo-cabin. During the recovery period, subjects were tested for biochemical markers, perceived pain sensation, and physical performance (squat jump, counter movement jump, maximal isometric torque production, and maximally explosive isometric torque production). Majority of the observed variables showed statistically significant time effects (P < 0.05) in control group, which indicates the presence of muscle damage. Significant interaction between the control and WBC condition was evident for the rate of torque development (P < 0.05). Pain measures substantially differed between the WBC and the control condition after the exercise. Results of this study are not completely supportive of the use of WBC for recovery enhancement after strenuous training. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  20. Effects of different duration isometric contractions on tendon elasticity in human quadriceps muscles

    PubMed Central

    Kubo, Keitaro; Kanehisa, Hiroaki; Fukunaga, Tetsuo

    2001-01-01

    The present study aimed to investigate the influence of isometric training protocols with long- and short-duration contractions on the elasticity of human tendon structures in vivo. The elasticity was assessed through in vivo determination of the elongation (L) of the tendons and aponeuroses using ultrasonography, while the subjects performed ramp isometric exercise up to maximum voluntary contraction (MVC).Eight young males completed 12 weeks (4 days per week) of a unilateral isometric training programme on knee extensors, which consisted of two different combinations of contraction and relaxation times at 70 % MVC: one leg was trained using a short-duration protocol (3 sets of 50 repetitions of contraction for 1 s and relaxation for 2 s), and the other leg was trained using a long-duration protocol (4 sets of a combination of contraction for 20 s and relaxation for 1 min). The training volume per session, expressed as the integrated torque, was the same for the two protocols.Both protocols resulted in a significant increase in MVC: 31.8 ± 17.2 % for the short-duration protocol and 33.9 ± 14.4 % for the long-duration protocol. Moreover, the training produced significant increases in the muscle volume of the constituents of the quadriceps femoris, with similar relative gains for the two protocols: 7.4 ± 3.9 % for the short-duration protocol and 7.6 ± 4.3 % for the long-duration protocol.The short-duration protocol produced no significant change in L values at any of the force production levels. For the long-duration protocol, however, the L values above 550 N were significantly shorter after training. Analysis revealed that the group × test time interaction effect on tendon stiffness was significant. Stiffness increased significantly for the long-duration protocol, but not for the short-duration protocol.The present study demonstrates a greater increase in stiffness of human tendon structures following isometric training using longer duration contractions

  1. The Effects of a Motorized Aquatic Treadmill Exercise Program on Muscle Strength, Cardiorespiratory Fitness, and clinical function in Subacute Stroke Patients -- a Randomized Controlled Pilot Trial.

    PubMed

    Lee, So Young; Han, Eun Young; Kim, Bo Ryun; Im, Sang Hee

    2018-03-12

    The aim of this study was to assess the effects of a motorized aquatic treadmill exercise program improve the isometric strength of the knee muscles, cardiorespiratory fitness, arterial stiffness, motor function, balance, functional outcomes and quality of life in subacute stroke patients. Thirty-two patients were randomly assigned to 4-week training sessions of either aquatic therapy(n=19) or land-based aerobic exercise(n=18). Isometric strength was measured using an isokinetic dynamometer. Cardiopulmonary fitness was evaluated using a symptom-limited exercise tolerance test and by measuring brachial ankle pulse wave velocity. Moreover, motor function(Fugl-Meyer Assessment[FMA] and FMA-lower limb[FMA-LL]), balance(Berg Balance Scale[BBS]), Activities of daily living(Korean version of the Modified Barthel Index [K-MBI]), and Quality of life(EQ-5D index) were examined. There were no inter-group differences between demographic and clinical characteristics at baseline(p>0.05). The results shows significant improvements in peak oxygen consumption (p=0.02), maximal isometric strength of the bilateral knee extensors (p<0.01) and paretic knee flexors (p=0.01), FMA (p=0.03), FMA-LL (p=0.01), BBS (p=0.01), K-MBI (p<0.01), and EQ-5D index (p=0.04) after treatment in the aquatic therapy group. However, only significant improvements in maximal isometric strength in the knee extensors (p=0.03) and flexors (p=0.04) were found within the aquatic therapy group and control group. Water-based aerobic exercise performed on a motorized aquatic treadmill had beneficial effect on isometric muscle strength in the lower limb.

  2. Effects of exercise on fluid exchange and body composition in man during 14-day bed rest

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Bernauer, E. M.; Juhos, L. T.; Young, H. L.; Morse, J. T.; Staley, R. W.

    1977-01-01

    A description is presented of an investigation in which body composition, fluid intake, and fluid and electrolyte losses were measured in seven normal, healthy men during three 2-wk bed-rest periods, separated by two 3-wk recovery periods. During bed rest the subjects remained in the horizontal position continuously. During the dietary control periods, body mass decreased significantly with all three regimens, including no exercise, isometric exercise, and isotonic excercise. During bed rest, body mass was essentially unchanged with no exercise, but decreased significantly with isotonic and isometric exercise. With one exception, there were no statistically significant changes in body density, lean body mass, or body fat content by the end of each of the three bed-rest periods.

  3. A Systematic Review of Isometric Lingual Strength-Training Programs in Adults With and Without Dysphagia

    PubMed Central

    Zhang, Bin; Haines, Morgan B.; Kelchner, Lisa N.

    2017-01-01

    Purpose This systematic review summarizes the effects of isometric lingual strength training on lingual strength and swallow function in adult populations. Furthermore, it evaluates the designs of the reviewed studies and identifies areas of future research in isometric lingual strength training for dysphagia remediation. Method A comprehensive literature search of 3 databases and additional backward citation search identified 10 studies for inclusion in the review. The review reports and discusses the isometric-exercise intervention protocols, pre- and postintervention lingual-pressure data (maximum peak pressures and lingual-palatal pressures during swallowing), and oropharyngeal swallowing measures such as penetration-aspiration scales, oropharyngeal residue and duration, lingual volumes, and quality-of-life assessments. Results Studies reported gains in maximum peak lingual pressures following isometric lingual strength training for both healthy adults and select groups of individuals with dysphagia. However, due to the variability in study designs, it remains unclear whether strength gains generalize to swallow function. Conclusion Although isometric lingual strength training is a promising intervention for oropharyngeal dysphagia, the current literature is too variable to confidently report specific therapeutic benefits. Future investigations should target homogenous patient populations and use randomized controlled trials to determine the efficacy of this treatment for individuals with dysphagia. PMID:28282484

  4. Suppression of Oxidative Stress by Resveratrol After Isometric Contractions in Gastrocnemius Muscles of Aged Mice

    PubMed Central

    Ryan, Michael J.; Jackson, Janna R.; Hao, Yanlei; Williamson, Courtney L.; Dabkowski, Erinne R.; Hollander, John M.

    2010-01-01

    This study tested the hypothesis that resveratrol supplementation would lower oxidative stress in exercised muscles of aged mice. Young (3 months) and aged (27 months) C57BL/6 mice received a control or a 0.05% trans-resveratrol-supplemented diet for 10 days. After 7 days of dietary intervention, 20 maximal electrically evoked isometric contractions were obtained from the plantar flexors of one limb in anesthetized mice. Exercise was conducted for three consecutive days. Resveratrol supplementation blunted the exercise-induced increase in xanthine oxidase activity in muscles from young (25%) and aged (53%) mice. Resveratrol lowered H2O2 levels in control (13%) and exercised (38%) muscles from aged animals, reduced Nox4 protein in both control and exercised muscles of young (30%) and aged mice (40%), and increased the ratio of reduced glutathione to oxidized glutathione in exercised muscles from young (38%) and aged (135%) mice. Resveratrol prevented the increase in lipid oxidation, increased catalase activity, and increased MnSOD activity in exercised muscles from aged mice. These data show that dietary resveratrol suppresses muscle indicators of oxidative stress in response to isometric contractions in aged mice. PMID:20507922

  5. Is there really an eccentric action of the hamstrings during the swing phase of high-speed running? Part II: Implications for exercise.

    PubMed

    Van Hooren, Bas; Bosch, Frans

    2017-12-01

    We have previously argued that there may actually be no significant eccentric, but rather predominantly an isometric action of the hamstring muscle fibres during the swing phase of high-speed running when the attachment points of the hamstrings are moving apart. Based on this we suggested that isometric rather than eccentric exercises are a more specific way of conditioning the hamstrings for high-speed running. In this review we argue that some of the presumed beneficial adaptations following eccentric training may actually not be related to the eccentric muscle fibre action, but to other factors such as exercise intensity. Furthermore, we discuss several disadvantages associated with commonly used eccentric hamstring exercises. Subsequently, we argue that high-intensity isometric exercises in which the series elastic element stretches and recoils may be equally or even more effective at conditioning the hamstrings for high-speed running, since they also avoid some of the negative side effects associated with eccentric training. We provide several criteria that exercises should fulfil to effectively condition the hamstrings for high-speed running. Adherence to these criteria will guarantee specificity with regards to hamstrings functioning during running. Practical examples of isometric exercises that likely meet several criteria are provided.

  6. Effects of Isometric Scaling on Vertical Jumping Performance

    PubMed Central

    Bobbert, Maarten F.

    2013-01-01

    Jump height, defined as vertical displacement in the airborne phase, depends on vertical takeoff velocity. For centuries, researchers have speculated on how jump height is affected by body size and many have adhered to what has come to be known as Borelli’s law, which states that jump height does not depend on body size per se. The underlying assumption is that the amount of work produced per kg body mass during the push-off is independent of size. However, if a big body is isometrically downscaled to a small body, the latter requires higher joint angular velocities to achieve a given takeoff velocity and work production will be more impaired by the force-velocity relationship of muscle. In the present study, the effects of pure isometric scaling on vertical jumping performance were investigated using a biologically realistic model of the human musculoskeletal system. The input of the model, muscle stimulation over time, was optimized using jump height as criterion. It was found that when the human model was miniaturized to the size of a mouse lemur, with a mass of about one-thousandth that of a human, jump height dropped from 40 cm to only 6 cm, mainly because of the force-velocity relationship. In reality, mouse lemurs achieve jump heights of about 33 cm. By implication, the unfavourable effects of the small body size of mouse lemurs on jumping performance must be counteracted by favourable effects of morphological and physiological adaptations. The same holds true for other small jumping animals. The simulations for the first time expose and explain the sheer magnitude of the isolated effects of isometric downscaling on jumping performance, to be counteracted by morphological and physiological adaptations. PMID:23936494

  7. Dynamic balance ability in young elite soccer players: implication of isometric strength.

    PubMed

    Chtara, Moktar; Rouissi, Mehdi; Bragazzi, Nicola L; Owen, Adam L; Haddad, Monoem; Chamari, Karim

    2018-04-01

    Soccer requires maintaining unilateral balance when executing movement with the contralateral leg. Despite the fact that balance requires standing with maintaining isometric posture with the support leg, currently there is a lack of studies regarding the implication of isometric strength on dynamic balance's performance among young soccer players. Therefore, the aim of this study was to examine the relationship between the Y-Balance Test and 12 lower limbs isometric strength tests. Twenty-six right footed soccer players (mean±SD, age=16.2±1.6 years, height=175±4.2 cm, body mass=68.8±6.1 kg) performed a dynamic balance test (star excursion balance-test with dominant- (DL) and nondominant-legs (NDL). Furthermore, maximal isometric contraction tests of 12 lower limb muscle groups were assessed in DL and NDL. Correlations analysis reported a significant positive relationship between some of isometric strength tests (with DL and NDL) and the Y-Balance Test. Furthermore, stepwise multiple regression analysis showed that maximal isometric strength explained between 21.9% and 49.4% of the variance of the Y-Balance Test. Moreover, maximal isometric strength was dependent upon the reaching angle of the Y-Balance Test and the leg used to support body weight. This study showed a significant implication of maximal isometric strength of the lower limb and the Y-Balance Test. Moreover, the present investigation suggests the implementation of specific lower limb strengthening exercises depending on players' deficit in each reaching direction and leg. This result suggests that further studies should experiment if increasing lower limbs isometric strength could improve dynamic balance ability among young soccer players.

  8. Using Maximal Isometric Force to Determine the Optimal Load for Measuring Dynamic Muscle Power

    NASA Technical Reports Server (NTRS)

    Spiering, Barry A.; Lee, Stuart M. C.; Mulavara, Ajitkumar P.; Bentley, Jason R.; Nash, Roxanne E.; Sinka, Joseph; Bloomberg, Jacob J.

    2009-01-01

    Maximal power output occurs when subjects perform ballistic exercises using loads of 30-50% of one-repetition maximum (1-RM). However, performing 1-RM testing prior to power measurement requires considerable time, especially when testing involves multiple exercises. Maximal isometric force (MIF), which requires substantially less time to measure than 1-RM, might be an acceptable alternative for determining the optimal load for power testing. PURPOSE: To determine the optimal load based on MIF for maximizing dynamic power output during leg press and bench press exercises. METHODS: Twenty healthy volunteers (12 men and 8 women; mean +/- SD age: 31+/-6 y; body mass: 72 +/- 15 kg) performed isometric leg press and bench press movements, during which MIF was measured using force plates. Subsequently, subjects performed ballistic leg press and bench press exercises using loads corresponding to 20%, 30%, 40%, 50%, and 60% of MIF presented in randomized order. Maximal instantaneous power was calculated during the ballistic exercise tests using force plates and position transducers. Repeated-measures ANOVA and Fisher LSD post hoc tests were used to determine the load(s) that elicited maximal power output. RESULTS: For the leg press power test, six subjects were unable to be tested at 20% and 30% MIF because these loads were less than the lightest possible load (i.e., the weight of the unloaded leg press sled assembly [31.4 kg]). For the bench press power test, five subjects were unable to be tested at 20% MIF because these loads were less than the weight of the unloaded aluminum bar (i.e., 11.4 kg). Therefore, these loads were excluded from analysis. A trend (p = 0.07) for a main effect of load existed for the leg press exercise, indicating that the 40% MIF load tended to elicit greater power output than the 60% MIF load (effect size = 0.38). A significant (p . 0.05) main effect of load existed for the bench press exercise; post hoc analysis indicated that the effect of

  9. The Effect of Isometric Massage on Global Grip Strength after Conservative Treatment of Distal Radial Fractures. Pilot Study.

    PubMed

    Ratajczak, Karina; Płomiński, Janusz

    2015-01-01

    The most common fracture of the distal end of the radius is Colles' fracture. Treatment modalities available for use in hand rehabilitation after injury include massage. The aim of this study was to evaluate the effect of isometric massage on the recovery of hand function in patients with Colles fractures. For this purpose, the strength of the finger flexors was assessed as an objective criterion for the evaluation of hand function. The study involved 40 patients, randomly divided into Group A of 20 patients and Group B of 20 patients. All patients received physical therapy and exercised individually with a physiotherapist. Isometric massage was additionally used in Group A. Global grip strength was assessed using a pneumatic force meter on the first and last day of therapy. Statistical analysis was performed using STATISTICA. Statistical significance was defined as a P value of less than 0.05. In both groups, global grip strength increased significantly after the therapy. There was no statistically significant difference between the groups. The men and women in both groups equally improved grip strength. A statistically significant difference was demonstrated between younger and older patients, with younger patients achieving greater gains in global grip strength in both groups. The incorporation of isometric massage in the rehabilitation plan of patients after a distal radial fracture did not significantly contribute to faster recovery of hand function or improve their quality of life.

  10. Effect of vibration during fatiguing resistance exercise on subsequent muscle activity during maximal voluntary isometric contractions.

    PubMed

    McBride, Jeffrey M; Porcari, John P; Scheunke, Mark D

    2004-11-01

    This investigation was designed to determine if vibration during fatiguing resistance exercise would alter associated patterns of muscle activity. A cross-over design was employed with 8 subjects completing a resistance exercise bout once with a vibrating dumbbell (V) (44 Hz, 3 mm displacement) and once without vibration (NV). For both exercise bouts, 10 sets were performed with a load that induced concentric muscle failure during the 10th repetition. The appropriate load for each set was determined during a pretest. Each testing session was separated by 1 week. Electromyography (EMG) was obtained from the biceps brachii muscle at 12 different time points during a maximum voluntary contraction (MVC) at a 170 degrees elbow angle after each set of the dumbbell exercise. The time points were as follows: pre (5 minutes before the resistance exercise bout), T1-T10 (immediately following each set of resistance exercise), and post (15 minutes after the resistance exercise bout). EMG was analyzed for median power frequency (MPF) and maximum (mEMG). NV resulted in a significant decrease in MPF at T1-T4 (p < or 0.05) and a significant increase in mEMG at T2 during the MVC. V had an overall trend of lower mEMG in comparison to NV. The mEMG and MPF values associated with NV were similar to previously reported investigations. The lower mEMG values and the higher MPF of V in comparison to NV are undocumented. The EMG patterns observed with vibration may indicate a more efficient and effective recruitment of high threshold motor units during fatiguing contractions. This may indicate the usage of vibration with resistance exercise as an effective tool for strength training athletes.

  11. The dose-response effect of medical exercise therapy on impairment in patients with unilateral longstanding subacromial pain.

    PubMed

    Osterås, Håvard; Torstensen, Tom Arild

    2010-01-05

    The primary aim of this study was to investigate the effect of medical exercise therapy in shoulder impingement patients, along with possible correlations between impairment variables. A prospective unblended randomized clinical trial. Over four months, 61 participants were randomly assigned into a high-graded exercise therapy group (HD) (n=31) and into a low-graded exercise therapy group (LD) (n=30). Prognostic variables were similar between the groups at baseline. Five (8%) patients dropped out during the treatment period, and another four (6%) dropped out before followup. Pain was a composite score of a visual analogue scale (VAS). Isometric strength was measured during four resisted break tests on the shoulder. Function was measured by means of a functional assessment questionnaire (Shoulder Rating Questionnaire, SRQ). Both groups trained three times per week for twelve weeks, with tests pre- and posttraining and six months follow-up. The HD group achieved significantly (p < 0.05) better outcome effects than the LD group for pain, range of motion, isometric functional strength and function, but both groups increased function from pretest to posttest. In patients with uncomplicated subacromial pain syndrome, medical exercise therapy is an efficient treatment alternative, where high-grade doses should be emphasized. A major limitation is that the measurements were not undertaken by another person than the treating physiotherapists.

  12. Effects of trunk stability on isometric knee extension muscle strength measurement while sitting.

    PubMed

    Hirano, Masahiro; Gomi, Masahiro; Katoh, Munenori

    2016-09-01

    [Purpose] This study aimed to investigate the effect of trunk stability on isometric knee extension muscle strength measurement while sitting by performing simultaneous measurements with a handheld dynamometer (HHD) and an isokinetic dynamometer (IKD) in the same seated condition. [Subjects and Methods] The subjects were 30 healthy volunteers. Isometric knee extension muscle strength was simultaneously measured with a HHD and an IKD by using an IKD-specific chair. The measurement was performed twice. Measurement instrument variables and the number of measurements were examined by using the analysis of variance and correlation tests. [Results] The measurement instrument variables and the number of measurements were not significantly different. The correlation coefficients between the HHD and IKD measurements were ≥0.96. [Conclusion] Isometric knee extension muscle strength measurement using the HHD in the sitting position resulted in a lower value than that using the IKD, presumably because of the effect of trunk stability on the measurement. In the same seated posture with trunk stability, no significant difference in measurement values was observed between the HHD and IKD. The present findings suggest that trunk stability while seated during isometric knee extension muscle strength measurement influenced the HHD measurement.

  13. Effect of fluid ingestion on neuromuscular function during prolonged cycling exercise.

    PubMed

    Vallier, J-M; Grego, F; Basset, F; Lepers, R; Bernard, T; Brisswalter, J

    2005-04-01

    To investigate the effects of fluid ingestion on neuromuscular function during prolonged cycling exercise. Eight well trained subjects exercised for 180 minutes in a moderate environment at a workload requiring approximately 60% maximal oxygen uptake. Two conditions, fluid (F) and no fluid (NF) ingestion, were investigated. During maximal voluntary isometric contraction (MVC), prolonged cycling exercise reduced (p<0.05) the maximal force generating capacity of quadriceps muscles (after three hours of cycling) and root mean square (RMS) values (after two hours of cycling) with no difference between the two conditions despite greater body weight loss (p<0.05) in NF. The mean power frequency (MPF) for vastus lateralis muscle was reduced (p<0.05) and the rate of force development (RFD) was increased (p<0.05) only during NF. During cycling exercise, integrated electromyographic activity and perceived exertion were increased in both conditions (p<0.05) with no significant effect of fluid ingestion. The results suggest that fluid ingestion did not prevent the previously reported decrease in maximal force with exercise duration, but seems to have a positive effect on some indicators of neuromuscular fatigue such as mean power frequency and rate of force development during maximal voluntary contraction. Further investigations are needed to assess the effect of change in hydration on neural mechanisms linked to the development of muscular fatigue during prolonged exercise.

  14. The Effects of Different Passive Static Stretching Intensities on Recovery from Unaccustomed Eccentric Exercise - A Randomized Controlled Trial.

    PubMed

    Apostolopoulos, Nikos C; Lahart, Ian M; Plyley, Michael J; Taunton, Jack; Nevill, Alan M; Koutedakis, Yiannis; Wyon, Matthew; Metsios, George S

    2018-03-12

    Effects of passive static stretching intensity on recovery from unaccustomed eccentric exercise of right knee extensors was investigated in 30 recreationally active males randomly allocated into three groups: high-intensity (70-80% maximum perceived stretch), low-intensity (30-40% maximum perceived stretch), and control. Both stretching groups performed 3 sets of passive static stretching exercises of 60s each for hamstrings, hip flexors, and quadriceps, over 3 consecutive days, post-unaccustomed eccentric exercise. Muscle function (eccentric and isometric peak torque) and blood biomarkers (CK and CRP) were measured before (baseline) and after (24, 48, and 72h) unaccustomed eccentric exercise. Perceived muscle soreness scores were collected immediately (time 0), and after 24, 48, and 72h post-exercise. Statistical time x condition interactions observed only for eccentric peak torque (p=.008). Magnitude-based inference analyses revealed low-intensity stretching had most likely, very likely, or likely beneficial effects on perceived muscle soreness (48-72h and 0-72h) and eccentric peak torque (baseline-24h and baseline-72h), compared with high-intensity stretching. Compared with control, low-intensity stretching had very likely or likely beneficial effects on perceived muscle soreness (0-24h and 0-72h), eccentric peak torque (baseline-48h and baseline-72h), and isometric peak torque (baseline-72h). High-intensity stretching had likely beneficial effects on eccentric peak torque (baseline-48h), but likely harmful effects eccentric peak torque (baseline-24h) and CK (baseline-48h and baseline-72h), compared with control. Therefore, low-intensity stretching is likely to result in small-to-moderate beneficial effects on perceived muscle soreness and recovery of muscle function post-unaccustomed eccentric exercise, but not markers of muscle damage and inflammation, compared with high-intensity or no stretching.

  15. The Effect of Water Temperature during Cold-Water Immersion on Recovery from Exercise-Induced Muscle Damage.

    PubMed

    Vieira, A; Siqueira, A F; Ferreira-Junior, J B; do Carmo, J; Durigan, J L Q; Blazevich, A; Bottaro, M

    2016-11-01

    This study investigated the effects of 5 and 15°C cold-water immersion on recovery from exercise resulting in exercise-induced muscle damage. 42 college-aged men performed 5×20 drop-jumps and were randomly allocated into one of 3 groups: (1) 5°C; (2) 15°C; or (3) control. After exercise, individuals from the cold-water immersion groups had their lower limbs immerged in iced water for 20 min. Isometric knee extensor torque, countermovement jump, muscle soreness, and creatine kinase were measured before, immediately after, 24, 48, 72, 96 and 168 h post-exercise. There was no between-group difference in isometric strength recovery (p=0.73). However, countermovement jump recovered quicker in cold-water immersion groups compared to control group (p<0.05). Countermovement jump returned to baseline after 72 h in 15°C, 5°C group recovered after 96 h and control did not recovered at any time point measured. Also, creatine kinase returned to baseline at 72 h and remained stable for all remaining measurements for 15°C group, whereas remained elevated past 168 h in both 5°C and control groups. There was a trend toward lower muscle soreness (p=0.06) in 15°C group compared to control at 24 h post-exercise. The result suggests that cold-water immersion promote recovery of stretch-shortening cycle performance, but not influence the recovery of maximal contractile force. Immersion at warmer temperature may be more effective than colder temperatures promoting recovery from strenuous exercise. © Georg Thieme Verlag KG Stuttgart · New York.

  16. 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.

  17. Electromyographic analysis of exercise resulting in symptoms of muscle damage.

    PubMed

    McHugh, M P; Connolly, D A; Eston, R G; Gleim, G W

    2000-03-01

    Surface electromyographic (EMG) signals were recorded from the hamstring muscles during six sets of submaximal isokinetic (2.6 rad x s(-1)) eccentric (11 men, 9 women) or concentric (6 men, 4 women) contractions. The EMG per unit torque increased during eccentric (P < 0.01) but not during concentric exercise. Similarly, the median frequency increased during eccentric (P < 0.01) but not during concentric exercise. The EMG per unit torque was lower for submaximal eccentric than maximum isometric contractions (P < 0.001), and lower for submaximal concentric than maximum isometric contractions (P < 0.01). The EMG per unit torque was lower for eccentric than concentric contractions (P < 0.05). The median frequency was higher for submaximal eccentric than maximum isometric contractions (P < 0.001); it was similar, however, between submaximal concentric and maximum isometric contractions (P = 0.07). Eccentric exercise resulted in significant isometric strength loss (P < 0.01), pain (P < 0.01) and muscle tenderness (P < 0.05). The greatest strength loss was seen 1 day after eccentric exercise, while the most severe pain and muscle tenderness occurred 2 days after eccentric exercise. A lower EMG per unit torque is consistent with the selective recruitment of a small number of motor units during eccentric exercise. A higher median frequency during eccentric contractions may be explained by selective recruitment of fast-twitch motor units. The present results are consistent with the theory that muscle damage results from excessive stress on a small number of active fibres during eccentric contractions.

  18. The effect of 6 days of alpha glycerylphosphorylcholine on isometric strength.

    PubMed

    Bellar, David; LeBlanc, Nina R; Campbell, Brian

    2015-01-01

    Ergogenic aides are widely used by fitness enthusiasts and athletes to increase performance. Alpha glycerylphosphorylcholine (A-GPC) has demonstrated some initial promise in changing explosive performance. The purpose of the present investigation was to determine if 6 days of supplementation with A-GPC would augment isometric force production compared to a placebo. Thirteen college-aged males (Means ± SD; Age: 21.9 ± 2.2 years, Height: 180.3 ± 7.7 cm, Weight: 87.6 ± 15.6 kg; VO2 max: 40.08 ± 7.23 ml O2*Kg(-1)*min(-1), Body Fat: 17.5 ± 4.6%) gave written informed consent to participate in the study. The study was a double blind, placebo controlled, cross-over design. The participants reported to the lab for an initial visit where they were familiarized with the isometric mid thigh pull in a custom squat cage on a force platform and upper body isometric test against a high frequency load cell, and baseline measurements were taken for both. The participant then consumed either 600 mg per day of A-GPC or placebo and at the end of 6 days performed isometric mid thigh pulls and an upper body isometric test. A one-week washout period was used before the participants' baseline was re-measured and crossed over to the other treatment. The A-GPC treatment resulted in significantly greater isometric mid thigh pull peak force change from baseline (t = 1.76, p = 0.044) compared with placebo (A-GPC: 98.8. ± 236.9 N vs Placebo: -39.0 ± 170.9 N). For the upper body test the A-GPC treatment trended towards greater change from baseline force production (A-GPC: 50.9 ± 67.2 N Placebo: -14.9 ± 114.9 N) but failed to obtain statistical significance (t = 1.16, p = 0.127). A-GPC is effective at increasing lower body force production after 6 days of supplementation. Sport performance coaches can consider adding A-GPC to the diet of speed and power athletes to enhance muscle performance.

  19. Optimization measurement of muscle oxygen saturation under isometric studies using FNIRS

    NASA Astrophysics Data System (ADS)

    Halim, A. A. A.; Laili, M. H.; Salikin, M. S.; Rusop, M.

    2018-05-01

    Development of functional near infrared spectroscopy (fNIRS) technologies has advanced quantification signal using multiple wavelength and detector to investigate hemodynamic response in human muscle. These non-invasive technologies have been widely used to solve the propagation of light inside the tissues including the absorption, scattering coefficient and to quantify the oxygenation level of haemoglobin and myoglobin in human muscle. The goal of this paper is to optimize the measurement of muscle oxygen saturation during isometric exercise using functional near infrared spectroscopy (fNIRS). The experiment was carried out on 15 sedentary healthy male volunteers. All volunteers are required to perform an isometric exercise at three assessment of muscular fatigue's level on flexor digitalis (FDS) muscle in the human forearm using fNIRS. The slopes of the signals have been highlighted to evaluate the muscle oxygen saturation of regional muscle fatigue. As a result, oxygen saturation slope from 10% exercise showed steeper than the first assessment at 30%-50% of fatigues level. The hemodynamic signal response showed significant value (p=0.04) at all three assessment of muscular fatigue's level which produce a p-value (p<0.05) measured by fNIRS. Thus, this highlighted parameter could be used to estimate fatigue's level of human and could open other possibilities to study muscle performance diagnosis.

  20. Age-related differences in skeletal muscle microvascular response to exercise as detected by contrast-enhanced ultrasound (CEUS).

    PubMed

    Hildebrandt, Wulf; Schwarzbach, Hans; Pardun, Anita; Hannemann, Lena; Bogs, Björn; König, Alexander M; Mahnken, Andreas H; Hildebrandt, Olaf; Koehler, Ulrich; Kinscherf, Ralf

    2017-01-01

    Aging involves reductions in exercise total limb blood flow and exercise capacity. We hypothesized that this may involve early age-related impairments of skeletal muscle microvascular responsiveness as previously reported for insulin but not for exercise stimuli in humans. Using an isometric exercise model, we studied the effect of age on contrast-enhanced ultrasound (CEUS) parameters, i.e. microvascular blood volume (MBV), flow velocity (MFV) and blood flow (MBF) calculated from replenishment of Sonovue contrast-agent microbubbles after their destruction. CEUS was applied to the vastus lateralis (VLat) and intermedius (VInt) muscle in 15 middle-aged (MA, 43.6±1.5 years) and 11 young (YG, 24.1±0.6 years) healthy males before, during, and after 2 min of isometric knee extension at 15% of peak torque (PT). In addition, total leg blood flow as recorded by femoral artery Doppler-flow. Moreover, fiber-type-specific and overall capillarisation as well as fiber composition were additionally assessed in Vlat biopsies obtained from CEUS site. MA and YG had similar quadriceps muscle MRT-volume or PT and maximal oxygen uptake as well as a normal cardiovascular risk factors and intima-media-thickness. During isometric exercise MA compared to YG reached significantly lower levels in MFV (0.123±0.016 vs. 0.208±0.036 a.u.) and MBF (0.007±0.001 vs. 0.012±0.002 a.u.). In the VInt the (post-occlusive hyperemia) post-exercise peaks in MBV and MBF were significantly lower in MA vs. YG. Capillary density, capillary fiber contacts and femoral artery Doppler were similar between MA and YG. In the absence of significant age-related reductions in capillarisation, total leg blood flow or muscle mass, healthy middle-aged males reveal impaired skeletal muscle microcirculatory responses to isometric exercise. Whether this limits isometric muscle performance remains to be assessed.

  1. Immediate effect of exercise on achilles tendon properties: systematic review.

    PubMed

    Obst, Steven J; Barrett, Rod S; Newsham-West, Richard

    2013-08-01

    Understanding the mechanical and morphological adaptation of the Achilles tendon (AT) in response to acute exercise could have important implications for athletic performance, injury prevention, and rehabilitation. The purpose of this study was to conduct a systematic review and critical evaluation of the literature to determine the immediate effect of a single bout of exercise on the mechanical and morphological properties of the AT in vivo. Five electronic research databases were systematically searched for intervention-based studies reporting mechanical and morphological properties of the AT after a single bout of exercise. Searches revealed 3292 possible articles; 21 met the inclusion criteria. There is evidence that maximal isometric contractions and prolonged static stretching (>5 min) of the triceps surae complex cause an immediate decrease in AT stiffness, whereas prolonged running and hopping have minimal effect. Limited but consistent evidence exists, indicating that AT hysteresis is reduced after prolonged static stretching. Consistent evidence supports a reduction in free AT diameter (anterior-posterior) after dynamic ankle exercise, and this change appears most pronounced in the healthy tendon and after eccentric exercise. The mechanical and morphological properties of the AT in vivo are affected by acute exercise in a mode- and dose-dependent manner. Transient changes in AT stiffness, hysteresis, and diameter after unaccustomed exercise modes and doses may expose the tendon to increased risk of strain injury and impact on the mechanical function of the triceps surae muscle-tendon unit.

  2. Strength Recovery Following Rhythmic or Sustained Exercise as a Function of Time.

    ERIC Educational Resources Information Center

    Kearney, Jay T.

    The relative rates of strength recovery subsequent to bouts of rhythmic or sustained isometric exercise were investigated. The 72 undergraduates who served as subjects were tested seven times within the framework of a repeated measures design. Each testing session involved two bouts of either rhythmic or sustained isometric exercise separated by a…

  3. Effects of neck strength training on isometric neck strength in rugby union players.

    PubMed

    Geary, Kevin; Green, Brian S; Delahunt, Eamonn

    2014-11-01

    To investigate the effectiveness of a neck strengthening program on the isometric neck strength profile of male rugby union players. Controlled laboratory study. Professional rugby union club. Fifteen professional and 10 semiprofessional rugby union players. The 15 professional players undertook a 5-week neck strengthening intervention, which was performed twice per week, whereas the 10 semiprofessional players acted as the control group. Isometric strength of the neck musculature was tested using a hand-held dynamometer, for flexion (F), extension (E), left-side flexion (LSF), and right-side flexion (RSF). Preintervention and postintervention evaluations were undertaken. No significant between-group differences in isometric neck strength were noted preintervention. A significant main effect for time was observed (P < 0.05), whereby the intervention group increased isometric neck strength in all planes after the 5-week intervention (F preintervention = 334.45 ± 39.31 N vs F postintervention 396.05 ± 75.55 N; E preintervention = 606.19 ± 97.34 vs E postintervention = 733.88 ± 127.16 N; LSF preintervention = 555.56 ± 88.34 N vs LSF postintervention = 657.14 ± 122.99 N; RSF preintervention = 570.00 ± 106.53 N vs RSF postintervention = 668.00 ± 142.18 N). No significant improvement in neck strength was observed for control group participants. The results of the present study indicate that a 5-week neck strengthening program improves isometric neck strength in rugby union players, which may have implications for injury prevention, screening, and rehabilitation. The strengthening program described in the present study may facilitate rehabilitation specialists in the development of neck injury prevention, screening, and rehabilitation protocols.

  4. A contralateral repeated bout effect attenuates induction of NF-κB DNA binding following eccentric exercise.

    PubMed

    Xin, Ling; Hyldahl, Robert D; Chipkin, Stuart R; Clarkson, Priscilla M

    2014-06-01

    We investigated the existence of contralateral repeated bout effect and tested if the attenuation of nuclear factor-kappa B (NF-κB; an important regulator of muscle inflammation) induction following eccentric exercise is a potential mechanism. Thirty-one healthy men performed two bouts of knee extension eccentric exercise, initially with one leg and then with the opposite leg 4 wk later. Vastus lateralis muscle biopsies of both exercised and control legs were taken 3 h postexercise. Knee extension isometric and isokinetic strength (60°/sec and 180°/sec) were measured at baseline, pre-exercise, immediately postexercise, and 1/day for 5 days postexercise. Serum creatine kinase (CK) activity and muscle soreness were assessed at baseline and 1/day for 5 days postexercise. NF-κB (p65) DNA-binding activity was measured in the muscle biopsies. Isometric strength loss was lower in bout 2 than in bout 1 at 24, 72, and 96 h postexercise (P < 0.05). Isokinetic strength (60°/s and 180°/s) was reduced less in bout 2 than in bout 1 at 72 h postexercise (P < 0.01). There were no significant differences between bouts for postexercise CK activity or muscle soreness. p65 DNA-binding activity was increased following eccentric exercise (compared with the control leg) in bout 1 (122.9% ± 2.6%; P < 0.001) and bout 2 (109.1% ± 3.0%; P < 0.05). Compared with bout 1, the increase in NF-κB DNA-binding activity postexercise was attenuated after bout 2 (P = 0.0008). Repeated eccentric exercise results in a contralateral repeated bout effect, which could be due to the attenuated increase in NF-κB activity postexercise. Copyright © 2014 the American Physiological Society.

  5. Transcutaneous electrical nerve stimulation reduces exercise-induced perceived pain and improves endurance exercise performance.

    PubMed

    Astokorki, Ali H Y; Mauger, Alexis R

    2017-03-01

    Muscle pain is a natural consequence of intense and prolonged exercise and has been suggested to be a limiter of performance. Transcutaneous electrical nerve stimulation (TENS) and interferential current (IFC) have been shown to reduce both chronic and acute pain in a variety of conditions. This study sought to ascertain whether TENS and IFC could reduce exercise-induced pain (EIP) and whether this would affect exercise performance. It was hypothesised that TENS and IFC would reduce EIP and result in an improved exercise performance. In two parts, 18 (Part I) and 22 (Part II) healthy male and female participants completed an isometric contraction of the dominant bicep until exhaustion (Part I) and a 16.1 km cycling time trial as quickly as they could (Part II) whilst receiving TENS, IFC, and a SHAM placebo in a repeated measures, randomised cross-over, and placebo-controlled design. Perceived EIP was recorded in both tasks using a validated subjective scale. In Part I, TENS significantly reduced perceived EIP (mean reduction of 12%) during the isometric contraction (P = 0.006) and significantly improved participants' time to exhaustion by a mean of 38% (P = 0.02). In Part II, TENS significantly improved (P = 0.003) participants' time trial completion time (~2% improvement) through an increased mean power output. These findings demonstrate that TENS can attenuate perceived EIP in a healthy population and that doing so significantly improves endurance performance in both submaximal isometric single limb exercise and whole-body dynamic exercise.

  6. Effects of air-pulsed cryotherapy on neuromuscular recovery subsequent to exercise-induced muscle damage.

    PubMed

    Guilhem, Gaël; Hug, François; Couturier, Antoine; Regnault, Stéphanie; Bournat, Laure; Filliard, Jean-Robert; Dorel, Sylvain

    2013-08-01

    Localized cooling has been proposed as an effective strategy to limit the deleterious effects of exercise-induced muscle damage on neuromuscular function. However, the literature reports conflicting results. This randomized controlled trial aimed to determine the effects of a new treatment, localized air-pulsed cryotherapy (-30°C), on the recovery time-course of neuromuscular function following a strenuous eccentric exercise. Controlled laboratory study. A total of 24 participants were included in either a control group (CONT) or a cryotherapy group (CRYO). Immediately after 3 sets of 20 maximal isokinetic eccentric contractions of elbow flexors, and then 1, 2, and 3 days after exercise, the CRYO group received a cryotherapy treatment (3 × 4 minutes at -30°C separated by 1 minute). The day before and 1, 2, 3, 7, and 14 days after exercise, several parameters were quantified: maximal isometric torque and its associated maximal electromyographic activity recorded by a 64-channel electrode, delayed-onset muscle soreness (DOMS), biceps brachii transverse relaxation time (T2) measured using magnetic resonance imaging, creatine kinase activity, interleukin-6, and C-reactive protein. Maximal isometric torque decreased similarly for the CONT (-33% ± 4%) and CRYO groups (-31% ± 6%). No intergroup differences were found for DOMS, electromyographic activity, creatine kinase activity, and T2 level averaged across the whole biceps brachii. C-reactive protein significantly increased for CONT (+93% at 72 hours, P < .05) but not for CRYO. Spatial analysis showed that cryotherapy delayed the significant increase of T2 and the decrease of electromyographic activity level for CRYO compared with CONT (between day 1 and day 3) in the medio-distal part of the biceps brachii. Although some indicators of muscle damage after severe eccentric exercise were delayed (ie, local formation of edema and decrease of muscle activity) by repeated air-pulsed cryotherapy, we provide evidence that

  7. [Hypertension and exercise. Sports methods for the hypertensive patient].

    PubMed

    Thiele, Holger; Pohlink, Carla; Schuler, Gerhard

    2004-06-01

    Physical exercise is of paramount therapeutic importance in nonpharmacological interventions of arterial hypertension. The extent and the effects of exercise on blood pressure lowering are analyzed according to the actual literature. Suitable and nonsuitable activities are considered. Dynamic isotonic endurance training is more effective than static isometric exercise. A rather low or moderate extent of endurance training lowers the systolic and diastolic blood pressure by approximately 5-11 mmHg and 3-8 mmHg, respectively. This effect of exercise can be achieved besides the favorable effects on other cardiovascular risk factors. Intensity of exercise should be monitored by the heart rate. The mean intensity should not exceed 70% of the maximal heart rate. An initial ergometry might be suitable for the planning of training recommendations.

  8. Alterations in Skeletal Muscle Function with Microgravity, and the Protective Effects of High Resistance Isometric and Isotonic Exercise

    NASA Technical Reports Server (NTRS)

    Fitts, R. H.; Hurst, J. E.; Norenberg, K. M.; Widrick, J. J.; Riley, D. A.; Bain, J. L. W.; Trappe, S. W.; Trappe, T. A.; Costill, D. L.

    1999-01-01

    Exposure to microgravity or models designed to mimic the unloaded condition, such as bed rest in humans and hindlimb unloading (HU) in rats leads to skeletal muscle atrophy, a loss in peak force and power, and an increased susceptibility to fatigue. The posterior compartment muscles of the lower leg (calf muscle group) appear to be particularly susceptible. Following only 1 wk in space or HU, rat soleus muscle showed a 30 to 40% loss in wet weight. After 3 wk of HU, almost all of the atrophied soleus fibers showed a significant increase in maximal shortening velocity (V(sub 0)), while only 25 to 30 % actually transitioned to fast fibers. The increased V(sub 0), was protective in that it reduced the decline in peak power associated with the reduced peak force. When the soleus is stimulated in situ following HU or zero-g one observes an increased rate and extent of fatigue, and in the former the increased fatigue is associated with a more rapid depletion of muscle glycogen and lactate production. Our working hypothesis is that following HU or spaceflight in rats and bed rest or spaceflight in humans limb skeletal muscles during contractile activity depend more on carbohydrates and less on fatty acids for their substrate supply. Baldwin et al. found 9 days of spaceflight to reduce by 37% the ability of both the high and low oxidative regions of the vastus muscle to oxidize long-chain fatty acids. This decline was not associated with any change in the enzymes of the tricarboxylic acid cycle or oxidation pathway. The purpose of the current research was to establish the extent of functional change in the slow type I and fast type H fibers of the human calf muscle following 17 days of spaceflight, and determine the cellular mechanisms of the observed changes. A second goal was to study the effectiveness of high resistance isotonic and isometric exercise in preventing the deleterious functional changes associated with unloading.

  9. Effects of combined β-hydroxy-β-methylbutyrate (HMB) and whey protein ingestion on symptoms of eccentric exercise-induced muscle damage.

    PubMed

    Shirato, Minayuki; Tsuchiya, Yosuke; Sato, Teruyuki; Hamano, Saki; Gushiken, Takeshi; Kimura, Naoto; Ochi, Eisuke

    2016-01-01

    The purpose of this study was to examine the effects of combined β-hydroxy-β-methylbutyrate (HMB) and whey protein ingestion on muscle strength and damage following a single bout of eccentric exercise. Eighteen untrained male subjects were assigned to HMB and Whey protein (HMB + Whey; 3 g/day HMB and 36.6 g/day whey protein, n = 6), HMB (3 g/day, n = 6), or whey protein (36.6 g/day, n = 6) groups. Ingestion commenced 7 days before non-dominant elbow flexor eccentric exercise (30 deg/sec, 6 reps × 7 sets) and continued until 4 days post-exercise. The maximal isometric strength, muscle soreness, plasma creatine kinase (CK), lactate dehydrogenase (LDH) were assessed pre-exercise, and at 1, 2, 3, and 5 days after exercise. The change scores of maximal isometric strength significantly decreased at day 1, 2, and 5 in the whey protein group compared to pre value and that in HMB + Whey protein and HMB groups decreased at day 1 and 5. The muscle soreness significantly increased in the whey and HMB + Whey protein groups at day 3 compared to pre value (p < 0.05). CK and LDH significantly increased (time effect: p < 0.05) after exercise. However, all data were not significant difference among the groups. These results suggest that ingestion of combined HMB and whey protein does not have a role to inhibit muscle strength loss and soreness, and decrease in muscle damage markers after eccentric exercise in comparison with HMB and whey protein alone.

  10. The influence of bar diameter on neuromuscular strength and activation: inferences from an isometric unilateral bench press.

    PubMed

    Fioranelli, Douglas; Lee, C Matthew

    2008-05-01

    The purpose of this study was to examine the influence of two different bar diameters on neuromuscular activation and strength. The bar diameters used reflected a standard Olympic bar (28 mm (1.1 inch); THIN) and a larger fat bar (51 mm [2 inch]; THICK). Eighteen healthy men (age 25.0 +/- 1 years) were assessed for their maximal voluntary contraction (MVC) during a unilateral isometric bench press exercise with the 2 bar types at 2 different joint angles (angle 1 and angle 2; elbow joint at approximately 45 and 90 degrees , respectively). Additionally, on a separate day, subjects performed three 10-second isometric repetitions at an intensity of 80% MVC using the 2 different bars at angle 1 and angle 2. Electromyographic recordings were collected in the pectoralis major and the muscles of the forearm flexor region at a sampling rate of 1000 Hz during the second day of testing. Analysis of variance was used to examine differences in MVC between bars and also examine between bar differences in electromyographic activity for each muscle group at each joint angle. A significance level of 0.05 was used for all tests. MVC was not different between bar types, although there was a main effect of joint angle on MVC such that it was greater at angle 2. There was a main effect of bar at both angles for the forearm muscles and at angle 1 for the pectoralis such that electromyographic activity was greater with THIN. Our data do not support the hypothesis that bar diameter influences performance during an isometric bench press exercise. However, higher electromyographic activity with THIN suggests greater neuromuscular activation with a standard Olympic bar as opposed to a larger diameter "fat" bar. Although our data do not support the use of a fat bar for increasing neuromuscular activation, these findings should be confirmed in other resistance training exercises.

  11. Rotator cuff exercises

    MedlinePlus

    ... activities, including your shoulder joint and your shoulder blade Observe your spine and posture as you stand ... band Isometric shoulder exercises Wall push-ups Shoulder blade (scapular) retraction - no tubing Shoulder blade (scapular) retraction - ...

  12. Effects of Exercise on Arrhythmia (and Viceversa): Lesson from the Greek Mythology.

    PubMed

    Lambiase, Caterina; Macerola, Silvia; Bosco, Giovanna; Messina, Elisa; Franciosa, Pasquale

    2017-01-01

    Exercise represents an important lifestyle factor in all human ages when felt in harmony with other psycho-physical and environmental variables that affect individual life (e. g. quality of interest, affections, environment, diet and food). Consequently, in addition to the training level, the amount, intensity and modality of exercise (ana-/aerobic, isometric/isotonic), need to be personalized, considering the underlying diseases, which may benefit from it or worsening.Greek mythology gives us good examples of the exercise concept's evolution.From Discus-thrower to Spear-carrier the idea of physical activity is more effectively expressed. The Myron Discobolus displays the enduring pattern of athletic energy translated into the dynamic force given by the exercise. In Doryphoros instead, the physical activity is oriented to the achievement of the required psyco-physical harmony, who's the concept is aimed of being expressed by the sculpture.As outlined below, even in the field of arrhythmia, scientific evidence as well as clinical experience, supports the same concept: physical activity may be important while safely managed and personalized.

  13. Age-related differences in skeletal muscle microvascular response to exercise as detected by contrast-enhanced ultrasound (CEUS)

    PubMed Central

    Hildebrandt, Wulf; Schwarzbach, Hans; Pardun, Anita; Hannemann, Lena; Bogs, Björn; König, Alexander M.; Mahnken, Andreas H.; Hildebrandt, Olaf; Koehler, Ulrich; Kinscherf, Ralf

    2017-01-01

    Background Aging involves reductions in exercise total limb blood flow and exercise capacity. We hypothesized that this may involve early age-related impairments of skeletal muscle microvascular responsiveness as previously reported for insulin but not for exercise stimuli in humans. Methods Using an isometric exercise model, we studied the effect of age on contrast-enhanced ultrasound (CEUS) parameters, i.e. microvascular blood volume (MBV), flow velocity (MFV) and blood flow (MBF) calculated from replenishment of Sonovue contrast-agent microbubbles after their destruction. CEUS was applied to the vastus lateralis (VLat) and intermedius (VInt) muscle in 15 middle-aged (MA, 43.6±1.5 years) and 11 young (YG, 24.1±0.6 years) healthy males before, during, and after 2 min of isometric knee extension at 15% of peak torque (PT). In addition, total leg blood flow as recorded by femoral artery Doppler-flow. Moreover, fiber-type-specific and overall capillarisation as well as fiber composition were additionally assessed in Vlat biopsies obtained from CEUS site. MA and YG had similar quadriceps muscle MRT-volume or PT and maximal oxygen uptake as well as a normal cardiovascular risk factors and intima-media-thickness. Results During isometric exercise MA compared to YG reached significantly lower levels in MFV (0.123±0.016 vs. 0.208±0.036 a.u.) and MBF (0.007±0.001 vs. 0.012±0.002 a.u.). In the VInt the (post-occlusive hyperemia) post-exercise peaks in MBV and MBF were significantly lower in MA vs. YG. Capillary density, capillary fiber contacts and femoral artery Doppler were similar between MA and YG. Conclusions In the absence of significant age-related reductions in capillarisation, total leg blood flow or muscle mass, healthy middle-aged males reveal impaired skeletal muscle microcirculatory responses to isometric exercise. Whether this limits isometric muscle performance remains to be assessed. PMID:28273102

  14. Enhanced knee joint function due to accelerated rehabilitation exercise after anterior cruciate ligament reconstruction surgery in Korean male high school soccer players.

    PubMed

    Lee, Myungchun; Sung, Dong Jun; Lee, Joohyung; Oh, Inyoung; Kim, Sojung; Kim, Seungho; Kim, Jooyoung

    2016-02-01

    This study was conducted on Korean male high school soccer players who underwent anterior cruciate ligament reconstruction (ACLR) to identify the effects of an accelerated rehabilitation exercise (ARE) program on knee joint isometric strength, thigh circumference, Lysholm score, and active balance agility. We assigned eight test participants each to a physical therapy group (PTG) and an accelerated rehabilitation exercise group (AREG), and compared differences between the groups. Both the PTG and AREG showed significant increases in 30° away and 60° toward isometric strength after treatment. In addition, significant differences were observed in these strength tests between the two groups. Both groups also showed significant increases in thigh circumference, Lysholm score, and active balance agility after treatment, but no significant differences were observed between the two groups. We conclude that the ARE treatment was more effective for improving isometric strength of the knee joint than that of physical therapy, and that an active rehabilitation exercise program after ACLR had positive effects on recovery performance of patients with an ACL injury and their return to the playing field.

  15. The Validity and Responsiveness of Isometric Lower Body Multi-Joint Tests of Muscular Strength: a Systematic Review.

    PubMed

    Drake, David; Kennedy, Rodney; Wallace, Eric

    2017-12-01

    Researchers and practitioners working in sports medicine and science require valid tests to determine the effectiveness of interventions and enhance understanding of mechanisms underpinning adaptation. Such decision making is influenced by the supportive evidence describing the validity of tests within current research. The objective of this study is to review the validity of lower body isometric multi-joint tests ability to assess muscular strength and determine the current level of supporting evidence. Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines were followed in a systematic fashion to search, assess and synthesize existing literature on this topic. Electronic databases such as Web of Science, CINAHL and PubMed were searched up to 18 March 2015. Potential inclusions were screened against eligibility criteria relating to types of test, measurement instrument, properties of validity assessed and population group and were required to be published in English. The Consensus-based Standards for the Selection of health Measurement Instruments (COSMIN) checklist was used to assess methodological quality and measurement property rating of included studies. Studies rated as fair or better in methodological quality were included in the best evidence synthesis. Fifty-nine studies met the eligibility criteria for quality appraisal. The ten studies that rated fair or better in methodological quality were included in the best evidence synthesis. The most frequently investigated lower body isometric multi-joint tests for validity were the isometric mid-thigh pull and isometric squat. The validity of each of these tests was strong in terms of reliability and construct validity. The evidence for responsiveness of tests was found to be moderate for the isometric squat test and unknown for the isometric mid-thigh pull. No tests using the isometric leg press met the criteria for inclusion in the best evidence synthesis. Researchers and

  16. Combined isometric and vibration training does not enhance strength beyond that of isometric training alone.

    PubMed

    Fisher, J; Van-Dongen, M; Sutherland, R

    2014-10-08

    Research considering combined vibration and strength training is extensive yet results are equivocal. However, to date there appears no research which has considered the combination of both direct vibration and whole---body vibration when used in an isometric deadlift position. The aims of this study were to compare groups performing isometric training with and without direct and whole---body vibration. Twenty four participants (19---24 years) were randomly divided into: isometric training with vibration (ST+VT: n=8), isometric training without vibration (ST: n=8), and control (CON: n=8). Within the training groups participants trained twice per week, for 6 weeks, performing 6---sets of maximal isometric deadlift contractions, increasing in duration from 30 seconds to 40 seconds (weeks 1---6). Hip and knee angle was maintained at 60° and 110°, respectively for both testing and training. Training sessions for ST+VT were identical to ST with the addition of a direct vibratory stimulus through hand---held straps and whole---body vibration via standing on vibration a platform. The amplitude remained constant (2mm) throughout the intervention whilst the frequency increased from 35Hz to 50Hz. Pre--- and post---test isometric strength was measured using an isometric deadlift dynamometer. Results revealed significant increases in isometric strength for both ST+VT (p < 0.001, 23.8%) and ST (p < 0.001, 32.5%) compared to CON, with no significant differences between ST+VT and ST training groups. The present study provides evidence to suggest that there are no greater gains to be incurred by the addition of a vibratory stimulus to traditional strength training.

  17. Combined isometric and vibration training does not enhance strength beyond that of isometric training alone.

    PubMed

    Fisher, J; Van-Dongen, M; Sutherland, R

    2015-09-01

    Research considering combined vibration and strength training is extensive yet results are equivocal. However, to date there appears no research which has considered the combination of both direct vibration and whole-body vibration when used in an isometric deadlift position. The aim of this study was to compare groups performing isometric training with and without direct and whole-body vibration. Twenty four participants (19-24 years) were randomly divided into: isometric training with vibration (ST+VT: N.=8), isometric training without vibration (ST: N.=8), and control (CON: N.=8). Within the training groups participants trained twice per week, for 6 weeks, performing 6-sets of maximal isometric deadlift contractions, increasing in duration from 30 seconds to 40 seconds (weeks 1-6). Hip and knee angle was maintained at 60° and 110°, respectively for both testing and training. Training sessions for ST+VT were identical to ST with the addition of a direct vibratory stimulus through hand-held straps and whole-body vibration via standing on vibration a platform. The amplitude remained constant (2 mm) throughout the intervention whilst the frequency increased from 35Hz to 50Hz. Pre- and post-test isometric strength was measured using an isometric deadlift dynamometer. Results revealed significant increases in isometric strength for both ST+VT (P<0.001, 23.8%) and ST (P<0.001, 32.5%) compared to CON, with no significant differences between ST+VT and ST training groups. The present study provides evidence to suggest that there are no greater gains to be incurred by the addition of a vibratory stimulus to traditional strength training.

  18. Blackcurrant Alters Physiological Responses and Femoral Artery Diameter during Sustained Isometric Contraction

    PubMed Central

    Cook, Matthew David; Myers, Stephen David; Gault, Mandy Lucinda; Willems, Mark Elisabeth Theodorus

    2017-01-01

    Blackcurrant is rich in anthocyanins that may affect exercise-induced physiological responses. We examined tissue oxygen saturation, muscle activity, cardiovascular responses and femoral artery diameter during a submaximal sustained isometric contraction. In a randomised, double-blind, crossover design, healthy men (n = 13, age: 25 ± 4 years, BMI: 25 ± 3 kg·m−2, mean ± SD) ingested New Zealand blackcurrant (NZBC) extract (600 mg∙day−1 CurraNZ™) or placebo (PL) for 7-days separated by 14-days washout. Participants produced isometric maximal voluntary contractions (iMVC) and a 120-s 30%iMVC of the quadriceps with electromyography (EMG), near-infrared spectroscopy, hemodynamic and ultrasound recordings. There was no effect of NZBC extract on iMVC (NZBC: 654 ± 73, PL: 650 ± 78 N). During the 30%iMVC with NZBC extract, total peripheral resistance, systolic, diastolic, and mean arterial pressure were lower with increased cardiac output and stroke volume. With NZBC extract, EMG root mean square of the vastus medialis and muscle oxygen saturation were lower with higher total haemoglobin. During the 30%iMVC, femoral artery diameter was increased with NZBC extract at 30 (6.9%), 60 (8.2%), 90 (7.7%) and 120 s (6.0%). Intake of NZBC extract for 7-days altered cardiovascular responses, muscle oxygen saturation, muscle activity and femoral artery diameter during a 120-s 30%iMVC of the quadriceps. The present study provides insight into the potential mechanisms for enhanced exercise performance with intake of blackcurrant. PMID:28555052

  19. Effects of flexi-bar and non-flexi-bar exercises on trunk muscles activity in different postures in healthy adults.

    PubMed

    Chung, Jun Sub; Park, Seol; Kim, JiYoung; Park, Ji Won

    2015-07-01

    [Purpose] The purpose of this study was to assess the effects of flexi-bar exercises and non-flexi-bar exercises on trunk muscle activity in different postures in healthy adults. [Subjects] Twenty healthy right-hand dominant adults (10 males and 10 females) were selected for this study. None of the participants had experienced any orthopedic problems in the spine or in the upper and lower extremities in the previous six months. [Methods] The subjects were instructed to adopt three exercise postures: posture 1, quadruped; posture 2, side-bridge; and posture 3, standing. Surface electromyography of selected trunk muscles was normalized to maximum voluntary isometric contraction. [Results] The external oblique, internal oblique, and erector spinae muscle activity showed significant differences between flexi-bar exercises and non-flexi-bar exercises. [Conclusion] The results of this study suggest that flexi-bar exercises are useful in the activation of trunk muscles.

  20. Relationship between innervation zone width and mean muscle fiber conduction velocity during a sustained isometric contraction.

    PubMed

    Ye, X; Beck, T W; Wages, N P

    2015-03-01

    To examine the relationship between the biceps brachii muscle innervation zone (IZ) width and the mean muscle fiber conduction velocity (MFCV) during a sustained isometric contraction. Fifteen healthy men performed a sustained isometric elbow flexion exercise at their 60% maximal voluntary contraction (MVC) until they could not maintain the target force. Mean MFCV was estimated through multichannel surface electromyographic recordings from a linear electrode array. Before exercise, IZ width was quantified. Separate non-parametric one-way analyses of variance (ANOVAs) were used to examine whether there was a difference in each mean MFCV variable among groups with different IZ width. In addition, separate bivariate correlations were also performed to examine the relationships between the IZ width and the mean MFCV variables during the fatiguing exercise. There was a significant difference in the percent decline of mean MFCV (%ΔMFCV) among groups with different IZ width (χ(2) (3)=11.571, p=0.009). In addition, there was also a significant positive relationship between the IZ width and the %ΔMFCV (Kendall's tau= 0.807; p<0.001). We believe that such relationship is likely influenced by both muscle fiber size and the muscle fiber type composition.

  1. Calculation of Resistive Loads for Elastic Resistive Exercises.

    PubMed

    Picha, Kelsey; Uhl, Tim

    2018-03-14

    What is the correct resistive load to start resistive training with elastic resistance to gain strength? This question is typically answered by the clinician's best estimate and patient's level of discomfort without objective evidence. To determine the average level of resistance to initiate a strengthening routine with elastic resistance following isometric strength testing. Cohort. Clinical. 34 subjects (31 ± 13 y, 73 ± 17 kg, 170 ± 12 cm). The force produced was measured in Newtons (N) with an isometric dynamometer. The force distance was the distance from center of joint to location of force applied was measured in meters to calculate torque that was called "Test Torque" for the purposes of this report. This torque data was converted to "Exercise Load" in pounds based on the location where the resistance was applied, specifically the distance away from the center of rotation of the exercising limb. The average amount of exercise load as percentage of initial Test Torque for each individual for each exercise was recorded to determine what the average level of resistance that could be used for elastic resistance strengthening program. The percentage of initial test torque calculated for the exercise was recorded for each exercise and torque produced was normalized to body weight. The average percentage of maximal isometric force that was used to initiate exercises was 30 ± 7% of test torque. This provides clinicians with an objective target load to start elastic resistance training. Individual variations will occur but utilization of a load cell during elastic resistance provides objective documentation of exercise progression.

  2. Comparison in muscle damage between maximal voluntary and electrically evoked isometric contractions of the elbow flexors.

    PubMed

    Jubeau, Marc; Muthalib, Makii; Millet, Guillaume Y; Maffiuletti, Nicola A; Nosaka, Kazunori

    2012-02-01

    This study compared between maximal voluntary (VOL) and electrically stimulated (ES) isometric contractions of the elbow flexors for changes in indirect markers of muscle damage to investigate whether ES would induce greater muscle damage than VOL. Twelve non-resistance-trained men (23-39 years) performed VOL with one arm and ES with the contralateral arm separated by 2 weeks in a randomised, counterbalanced order. Both VOL and ES (frequency 75 Hz, pulse duration 250 μs, maximally tolerated intensity) exercises consisted of 50 maximal isometric contractions (4-s on, 15-s off) of the elbow flexors at a long muscle length (160°). Changes in maximal voluntary isometric contraction torque (MVC), range of motion, muscle soreness, pressure pain threshold and serum creatine kinase (CK) activity were measured before, immediately after and 1, 24, 48, 72 and 96 h following exercise. The average peak torque over the 50 isometric contractions was greater (P < 0.05) for VOL (32.9 ± 9.8 N m) than ES (16.9 ± 6.3 N m). MVC decreased greater and recovered slower (P < 0.05) after ES (15% lower than baseline at 96 h) than VOL (full recovery). Serum CK activity increased (P < 0.05) only after ES, and the muscles became more sore and tender after ES than VOL (P < 0.05). These results showed that ES induced greater muscle damage than VOL despite the lower torque output during ES. It seems likely that higher mechanical stress imposed on the activated muscle fibres, due to the specificity of motor unit recruitment in ES, resulted in greater muscle damage.

  3. Estimations of One Repetition Maximum and Isometric Peak Torque in Knee Extension Based on the Relationship Between Force and Velocity.

    PubMed

    Sugiura, Yoshito; Hatanaka, Yasuhiko; Arai, Tomoaki; Sakurai, Hiroaki; Kanada, Yoshikiyo

    2016-04-01

    We aimed to investigate whether a linear regression formula based on the relationship between joint torque and angular velocity measured using a high-speed video camera and image measurement software is effective for estimating 1 repetition maximum (1RM) and isometric peak torque in knee extension. Subjects comprised 20 healthy men (mean ± SD; age, 27.4 ± 4.9 years; height, 170.3 ± 4.4 cm; and body weight, 66.1 ± 10.9 kg). The exercise load ranged from 40% to 150% 1RM. Peak angular velocity (PAV) and peak torque were used to estimate 1RM and isometric peak torque. To elucidate the relationship between force and velocity in knee extension, the relationship between the relative proportion of 1RM (% 1RM) and PAV was examined using simple regression analysis. The concordance rate between the estimated value and actual measurement of 1RM and isometric peak torque was examined using intraclass correlation coefficients (ICCs). Reliability of the regression line of PAV and % 1RM was 0.95. The concordance rate between the actual measurement and estimated value of 1RM resulted in an ICC(2,1) of 0.93 and that of isometric peak torque had an ICC(2,1) of 0.87 and 0.86 for 6 and 3 levels of load, respectively. Our method for estimating 1RM was effective for decreasing the measurement time and reducing patients' burden. Additionally, isometric peak torque can be estimated using 3 levels of load, as we obtained the same results as those reported previously. We plan to expand the range of subjects and examine the generalizability of our results.

  4. Chronic Effects of Different Rest Intervals Between Sets on Dynamic and Isometric Muscle Strength and Muscle Activity in Trained Older Women.

    PubMed

    Jambassi Filho, José Claudio; Gurjão, André Luiz Demantova; Ceccato, Marilia; Prado, Alexandre Konig Garcia; Gallo, Luiza Herminia; Gobbi, Sebastião

    2017-09-01

    This study investigated the chronic effects of different rest intervals (RIs) between sets on dynamic and isometric muscle strength and muscle activity. We used a repeated-measures design (pretraining and posttraining) with independent groups (different RI). Twenty-one resistance-trained older women (66.4 ± 4.4 years) were randomly assigned to either a 1-minute RI group (G-1 min; n = 10) or 3-minute RI group (G-3 min; n = 11). Both groups completed 3 supervised sessions per week during 8 weeks. In each session, participants performed 3 sets of 15 repetitions of leg press exercise, with a load that elicited muscle failure in the third set. Fifteen maximum repetitions, maximal voluntary contraction, peak rate of force development, and integrated electromyography activity of the vastus lateralis and vastus medialis muscles were assessed pretraining and posttraining. There was a significant increase in load of 15 maximum repetitions posttraining for G-3 min only (3.6%; P < 0.05). However, posttraining results showed no significant differences between G-1 min and G-3 min groups for all dependent variables (P > 0.05). The findings suggest that different RIs between sets did not influence dynamic and isometric muscle strength and muscle activity in resistance-trained older women.

  5. A gravity exercise system. [for muscle conditioning during manned space flight

    NASA Technical Reports Server (NTRS)

    Brandt, W. E.; Clark, A. L.

    1973-01-01

    An effective method for muscle conditioning during weightlessness flight is derived from isometric exercise. The basic principle of gravity exercise is to periodically displace the human body upon reactionless rollers so that spacial equilibrium can only be maintained by the proper tension and relaxation of the body's muscles. A rotating platform mounted upon two degrees of freedom rollers provides such a condition of gravitational reaction stress throughout each of its 360 deg rotation.

  6. The acute effects of exercise on cigarette cravings, withdrawal symptoms, affect, and smoking behaviour: systematic review update and meta-analysis.

    PubMed

    Roberts, Vaughan; Maddison, Ralph; Simpson, Caroline; Bullen, Chris; Prapavessis, Harry

    2012-07-01

    Smoking cessation is associated with cigarette cravings and tobacco withdrawal symptoms (TWS), and exercise appears to ameliorate many of these negative effects. A number of studies have examined the relationships between exercise, cigarette cravings, and TWS. The objectives of this study were (a) to review and update the literature examining the effects of short bouts of exercise on cigarette cravings, TWS, affect, and smoking behaviour and (b) to conduct meta-analyses of the effect of exercise on cigarette cravings. A systematic review of all studies published between January 2006 and June 2011 was conducted. Fifteen new studies were identified, 12 of which found a positive effect of exercise on cigarette cravings. The magnitude of statistically significant effect sizes for 'desire to smoke' and 'strength of desire to smoke' ranged from 0.4 to 1.98 in favour of exercise compared to passive control conditions, and peaked either during or soon after treatment. Effects were found up to 30 min post-exercise. Cigarette cravings were reduced following exercise with a wide range of intensities from isometric exercise and yoga to activity as high as 80-85 % heart rate reserve. Meta-analyses revealed weighted mean differences of -1.90 and -2.41 in 'desire to smoke' and 'strength of desire to smoke' outcomes, respectively. Measures of TWS and negative affect were reduced following light-moderate intensity exercise, but increased during vigorous exercise. Exercise can have a positive effect on cigarette cravings and TWS. However, the most effective exercise intensity to reduce cravings and the underlying mechanisms associated with this effect remain unclear.

  7. Reduced Metaboreflex Control of Blood Pressure during Exercise in Individuals with Intellectual Disability: A Possible Contributor to Exercise Intolerance

    ERIC Educational Resources Information Center

    Dipla, K.; Zafeiridis, A.; Papadopoulos, S.; Koskolou, M.; Geladas, N.; Vrabas, I. S.

    2013-01-01

    The aim was to investigate the hemodynamic responses to isometric handgrip exercise (HG) and examine the role of the muscle metaboreflex in the exercise pressor response in individuals with intellectual disability (IID) and non-disabled control subjects. Eleven males with mild-moderate intellectual disabilities and eleven non-disabled males…

  8. Long-term effects of a very low-carbohydrate weight loss diet on exercise capacity and tolerance in overweight and obese adults.

    PubMed

    Wycherley, Thomas P; Buckley, Jonathan D; Noakes, Manny; Clifton, Peter M; Brinkworth, Grant D

    2014-01-01

    Compare the long-term effects of an energy-restricted very low-carbohydrate, high-fat (LC) diet with an isocaloric high-carbohydrate, low-fat (HC) diet on exercise tolerance and capacity in overweight and obese adults. Seventy-six adults (25 males; age 49.2 ± 1.1 years; BMI 33.6 ± 0.5 kg/m(2)) were randomized to either a hypocaloric (6-7 MJ/day) LC diet (35% protein, 4% carbohydrate, 61% fat) or isocaloric HC diet (24% protein, 46% carbohydrate, 30% fat) for 52 weeks. Pre- and postintervention, participants' body weight and composition, handgrip, and isometric knee extensor strength were assessed and participants performed an incremental exercise test to exhaustion. Forty-three participants completed the study (LC = 23; HC = 20). Overall, peak relative oxygen uptake increased (+11.3%) and reductions occurred in body weight (-14.6%), body fat percentage (-6.9% [absolute]), isometric knee extensor strength (-12.4%), handgrip strength (-4.5%), and absolute peak oxygen uptake (-5.2%; p ≤ 0.02 time for all) with no diet effect (p ≥ 0.18). During submaximal exercise, rating of perceived exertion did not change in either group (p = 0.16 time, p = 0.59 Time × Group). Compared to the HC diet, the LC diet had greater reductions in respiratory exchange ratio (LC -0.04 ± 0.01, HC -0.00 ± 0.01; p = 0.03), and increased fat oxidation (LC 15.0 ± 5.3% [of energy expenditure], HC 0.5 ± 3.9%; p = 0.04). In overweight and obese patients, an LC diet promoted greater fat utilization during submaximal exercise. Both an LC diet and an HC diet had similar effects on aerobic capacity and muscle strength, suggesting that long-term consumption of an LC weight loss diet does not adversely affect physical function or the ability to perform exercise.

  9. Effect of hydrotherapy on the signs and symptoms of delayed onset muscle soreness.

    PubMed

    Vaile, Joanna; Halson, Shona; Gill, Nicholas; Dawson, Brian

    2008-03-01

    This study independently examined the effects of three hydrotherapy interventions on the physiological and functional symptoms of delayed onset muscle soreness (DOMS). Strength trained males (n = 38) completed two experimental trials separated by 8 months in a randomised crossover design; one trial involved passive recovery (PAS, control), the other a specific hydrotherapy protocol for 72 h post-exercise; either: (1) cold water immersion (CWI: n = 12), (2) hot water immersion (HWI: n = 11) or (3) contrast water therapy (CWT: n = 15). For each trial, subjects performed a DOMS-inducing leg press protocol followed by PAS or one of the hydrotherapy interventions for 14 min. Weighted squat jump, isometric squat, perceived pain, thigh girths and blood variables were measured prior to, immediately after, and at 24, 48 and 72 h post-exercise. Squat jump performance and isometric force recovery were significantly enhanced (P < 0.05) at 24, 48 and 72 h post-exercise following CWT and at 48 and 72 h post-exercise following CWI when compared to PAS. Isometric force recovery was also greater (P < 0.05) at 24, 48, and 72 h post-exercise following HWI when compared to PAS. Perceived pain improved (P < 0.01) following CWT at 24, 48 and 72 h post-exercise. Overall, CWI and CWT were found to be effective in reducing the physiological and functional deficits associated with DOMS, including improved recovery of isometric force and dynamic power and a reduction in localised oedema. While HWI was effective in the recovery of isometric force, it was ineffective for recovery of all other markers compared to PAS.

  10. Resistance exercise improves muscle strength, health status and pain intensity in fibromyalgia--a randomized controlled trial.

    PubMed

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

    2015-06-18

    Fibromyalgia (FM) is characterized by persistent widespread pain, increased pain sensitivity and tenderness. Muscle strength in women with FM is reduced compared to healthy women. The aim of this study was to examine the effects of a progressive resistance exercise program on muscle strength, health status, and current pain intensity in women with FM. A total of 130 women with FM (age 22-64 years, symptom duration 0-35 years) were included in this assessor-blinded randomized controlled multi-center trial examining the effects of progressive resistance group exercise compared with an active control group. A person-centred model of exercise was used to support the participants' self-confidence for management of exercise because of known risks of activity-induced pain in FM. The intervention was performed twice a week for 15 weeks and was supervised by experienced physiotherapists. Primary outcome measure was isometric knee-extension force (Steve Strong®), secondary outcome measures were health status (FIQ total score), current pain intensity (VAS), 6MWT, isometric elbow-flexion force, hand-grip force, health related quality of life, pain disability, pain acceptance, fear avoidance beliefs, and patient global impression of change (PGIC). Outcomes were assessed at baseline and immediately after the intervention. Long-term follow up comprised the self-reported questionnaires only and was conducted after 13-18 months. Between-group and within-group differences were calculated using non-parametric statistics. Significant improvements were found for isometric knee-extension force (p = 0.010), health status (p = 0.038), current pain intensity (p = 0.033), 6MWT (p = 0.003), isometric elbow flexion force (p = 0.02), pain disability (p = 0.005), and pain acceptance (p = 0.043) in the resistance exercise group (n = 56) when compared to the control group (n = 49). PGIC differed significantly (p = 0.001) in favor of the resistance exercise group at post-treatment examinations

  11. Effects of cold water immersion and active recovery on hemodynamics and recovery of muscle strength following resistance exercise.

    PubMed

    Roberts, Llion A; Muthalib, Makii; Stanley, Jamie; Lichtwark, Glen; Nosaka, Kazunori; Coombes, Jeff S; Peake, Jonathan M

    2015-08-15

    Cold water immersion (CWI) and active recovery (ACT) are frequently used as postexercise recovery strategies. However, the physiological effects of CWI and ACT after resistance exercise are not well characterized. We examined the effects of CWI and ACT on cardiac output (Q̇), muscle oxygenation (SmO2), blood volume (tHb), muscle temperature (Tmuscle), and isometric strength after resistance exercise. On separate days, 10 men performed resistance exercise, followed by 10 min CWI at 10°C or 10 min ACT (low-intensity cycling). Q̇ (7.9 ± 2.7 l) and Tmuscle (2.2 ± 0.8°C) increased, whereas SmO2 (-21.5 ± 8.8%) and tHb (-10.1 ± 7.7 μM) decreased after exercise (P < 0.05). During CWI, Q̇ (-1.1 ± 0.7 l) and Tmuscle (-6.6 ± 5.3°C) decreased, while tHb (121 ± 77 μM) increased (P < 0.05). In the hour after CWI, Q̇ and Tmuscle remained low, while tHb also decreased (P < 0.05). By contrast, during ACT, Q̇ (3.9 ± 2.3 l), Tmuscle (2.2 ± 0.5°C), SmO2 (17.1 ± 5.7%), and tHb (91 ± 66 μM) all increased (P < 0.05). In the hour after ACT, Tmuscle, and tHb remained high (P < 0.05). Peak isometric strength during 10-s maximum voluntary contractions (MVCs) did not change significantly after CWI, whereas it decreased after ACT (-30 to -45 Nm; P < 0.05). Muscle deoxygenation time during MVCs increased after ACT (P < 0.05), but not after CWI. Muscle reoxygenation time after MVCs tended to increase after CWI (P = 0.052). These findings suggest first that hemodynamics and muscle temperature after resistance exercise are dependent on ambient temperature and metabolic demands with skeletal muscle, and second, that recovery of strength after resistance exercise is independent of changes in hemodynamics and muscle temperature. Copyright © 2015 the American Physiological Society.

  12. Beta-alanine supplementation improves isometric, but not isotonic or isokinetic strength endurance in recreationally strength-trained young men.

    PubMed

    Bassinello, Diogo; de Salles Painelli, Vitor; Dolan, Eimear; Lixandrão, Manoel; Cajueiro, Monique; de Capitani, Mariana; Saunders, Bryan; Sale, Craig; Artioli, Guilherme G; Gualano, Bruno; Roschel, Hamilton

    2018-06-15

    β-Alanine (BA) supplementation may be ergogenic during high-intensity exercise, primarily due to the buffering of hydrogen cations, although the effects of beta-alanine supplementation on strength endurance are equivocal. The aim of the study was to determine the effects of 4 weeks of beta-alanine supplementation on skeletal muscle endurance using a battery of performance tests. This study employed a parallel group, repeated measures, randomised, double-blinded and placebo-controlled design. Twenty recreationally strength-trained healthy males completed tests of isotonic strength endurance (repeated bench and leg press), along with tests of isometric and isokinetic endurance conducted using an isokinetic dynamometer. Tests were performed before and after a 4 week intervention, comprising an intake of 6.4 g day -1 of BA (n = 9) or placebo (maltodextrin, n = 11). Time-to-exhaustion during the isometric endurance test improved by ~ 17% in the BA group (p < 0.01), while PL remained unchanged. No significant within-group differences (p > 0.1) were shown for any of the performance variables in the isokinetic test (peak torque, fatigue index, total work) nor for the total number of repetitions performed in the isotonic endurance tests (leg or bench press). Four weeks of BA supplementation (6.4 g day -1 ) improved isometric, but not isokinetic or isotonic endurance performance.

  13. Supervised Versus Home Exercise Training Programs on Functional Balance in Older Subjects.

    PubMed

    Youssef, Enas Fawzy; Shanb, Alsayed Abd Elhameed

    2016-11-01

    Aging is associated with a progressive decline in physical capabilities and a disturbance of both postural control and daily living activities. The aim of this study was to evaluate the effects of supervised versus home exercise programs on muscle strength, balance and functional activities in older participants. Forty older participants were equally assigned to a supervised exercise program (group-I) or a home exercise program (group-II). Each participant performed the exercise program for 35-45 minutes, two times per week for four months. Balance indices and isometric muscle strength were measured with the Biodex Balance System and Hand-Held Dynamometer. Functional activities were evaluated by the Berg Balance Scale (BBS) and the timed get-up-and-go test (TUG). The mean values of the Biodex balance indices and the BBS improved significantly after both the supervised and home exercise programs ( P < 0.05). However, the mean values of the TUG and muscle strength at the ankle, knee and hip improved significantly only after the supervised program. A comparison between the supervised and home exercise programs revealed there were only significant differences in the BBS, TUG and muscle strength. Both the supervised and home exercise training programs significantly increased balance performance. The supervised program was superior to the home program in restoring functional activities and isometric muscle strength in older participants.

  14. Cardiorespiratory deconditioning with static and dynamic leg exercise during bed rest

    NASA Technical Reports Server (NTRS)

    Stremel, R. W.; Convertino, V. A.; Bernauer, E. M.; Greenleaf, J. E.

    1976-01-01

    Results are presented for an experimental study designed to compare the effects of heavy static and dynamic exercise training during 14 days of bed rest on the cardiorespiratory responses to submaximal and maximal exercise performed by seven healthy men aged 19-22 yr. The parameters measured were submaximal and maximal oxygen uptake, minute ventilation, heart rate, and plasma volume. The results indicate that exercise alone during bed rest reduces but does not eliminate the reduction in maximal oxygen uptake. An additional positive hydrostatic effect is therefore necessary to restore maximal oxygen uptake to ambulatory control levels. The greater protective effect of static exercise on maximal oxygen uptake is probably due to a greater hydrostatic component from the isometric muscular contraction. Neither the static nor the dynamic exercise training regimes are found to minimize the changes in all the variables studied, thereby suggesting a combination of static and dynamic exercises.

  15. Spine lateral flexion strength development differences between exercises with pelvic stabilization and without pelvic stabilization

    NASA Astrophysics Data System (ADS)

    Straton, Alexandru; Gidu, Diana Victoria; Micu, Alexandru

    2015-02-01

    Poor lateral flexor muscle strength can be an important source of lumbar/thoracic back pain in women. The purpose of this study was to evaluate pelvic stabilization (PS) and no pelvic stabilization (NoPS) lateral flexion strength exercise training on the development of isolated right and left lateral flexion strength. Isometric torque of the isolated right and left lateral flexion muscles was measured at two positions (0° and 30° opposed angle range of motion) on 42 healthy women before and after 8 weeks of PS and NoPS lateral flexion strength exercise training. Subjects were assigned in three groups, the first (n=14) trained 3 times/week with PS lateral flexion strength exercise, the second (n=14) trained 3 times/week with NoPS lateral flexion strength exercise and the third (control, n=14) did not train. Post training isometric strength values describing PS and NoPS lateral flexion strength improved in greater extent for the PS lateral flexion strength exercise group and in lesser extent for the NoPS lateral flexion strength exercise group, in both angles (p<0.05) relative to controls. These data indicate that the most effective way of training the spine lateral flexion muscles is PS lateral flexion strength exercises; NoPS lateral flexion strength exercises can be an effective way of training for the spine lateral flexion muscles, if there is no access to PS lateral flexion strength training machines.

  16. 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.

  17. Effect of strain on actomyosin kinetics in isometric muscle fibers.

    PubMed

    Siththanandan, V B; Donnelly, J L; Ferenczi, M A

    2006-05-15

    Investigations were conducted into the biochemical and mechanical states of cross-bridges during isometric muscle contraction. Rapid length steps (3 or 6 nm hs(-1)) were applied to rabbit psoas fibers, permeabilized and isometric, at either 12 degrees C or 20 degrees C. Fibers were activated by photolysis of P(3)-1-(2-nitrophenyl)-ethyl ester of ATP infused into rigor fibers at saturating Ca(2+). Sarcomere length, tension, and phosphate release were recorded-the latter using the MDCC-PBP fluorescent probe. A reduction in strain, induced by a rapid release step, produced a short-lived acceleration of phosphate release. Rates of the phosphate transient and that of phases 3 and 4 of tension recovery were unaffected by step size but were elevated at higher temperatures. In contrast the amplitude of the phosphate transient was smaller at 20 degrees C than 12 degrees C. The presence of 0.5 or 1.0 mM added ADP during a release step reduced both the rate of tension recovery and the poststep isometric tension. A kinetic scheme is presented to simulate the observed data and to precisely determine the rate constants for the elementary steps of the ATPase cycle.

  18. Effects of Isometric Hand-Grip Muscle Contraction on Young Adults' Free Recall and Recognition Memory.

    PubMed

    Tomporowski, Phillip D; Albrecht, Chelesa; Pendleton, Daniel M

    2017-03-01

    The purpose of this study was to determine if physical arousal produced by isometric hand-dynamometer contraction performed during word-list learning affects young adults' free recall or recognition memory. Twenty-four young adults (12 female; M age  = 22 years) were presented with 4 20-item word lists. Moderate arousal was induced in 12 adults by an initial 30-s maximal hand-dynamometer squeeze with force productions of 50% maximum; low arousal was induced in 12 adults by an initial 1-s maximal dynamometer squeeze with force production of 10% maximum during learning. Memory performances following dual-task conditions experienced during the encoding, consolidation, and recall phases of learning were compared to a single-task control condition during which words were learned in the absence of isometric exercise. Planned contrasts revealed that arousal coinciding with word encoding led to significantly poorer immediate recall, F(1, 23) = 10.13, p < .05, [Formula: see text] = .31, delayed free recall, F(1, 23) = 15.81, p < .05, [Formula: see text] = .41, and recognition memory, F(1, 23) = 6.07, p < .05, [Formula: see text] = .21, compared with when there was no arousal. Neither arousal condition facilitated participants' memory performance. The reduction in long-term memory performance specific to the encoding phase of learning is explained in terms of the dual-task attentional demands placed on participants.

  19. Hiking physiology and the "quasi-isometric" concept.

    PubMed

    Spurway, Neil C

    2007-08-01

    The literature indicates that the heart rate of a planing-dinghy sailor, in winds of 4 - 5 m . s(-1), is in the range seen in aerobic athletes, yet oxygen consumption (VO(2)) is roughly half that of the same individual cycling at that heart rate. Thus, although upper-body dynamic activity is a contributing factor, the dominant physiological demand must be the "quasi-isometric" stress on the lower-body anterior muscles - especially the quadriceps, which appears to impose 40 - 50% of the total oxygen demand in a typical hiking posture. Therefore, a non-trivial part of the sailor's fitness training should involve sustained quadriceps stress. Estimates of this stress on water vary widely in the literature, but about 25 - 30% maximal voluntary contraction (MVC) tallies with endurance times recorded both in the literature and in an outline of new work reported here. Muscle blood flow is restricted under such a load, but not occluded. Laser Doppler measurements of femoral blood flow on a leg-extension ergometer found similar values during 10 - 30% MVC, much less at 40%, and marked hyperaemia on relaxation from 20% MVC or more - implying metabolic debt. Adding low-amplitude alternating leg movements while holding the same overall load stationary, and therefore increasing only internal not external work, further elevates blood flow and VO(2) both during and after exercise. Femoral-vein lactate concentration is also higher after these movements. Speculations that unusually dynamic lower-body movements by elite sailors might assist hiking endurance are not supported by these findings. Nevertheless, afloat or ashore, capillary lactate concentrations hardly ever exceed 5 mmol . l(-1), even during the post-exercise surge - challenging assumptions that the quadriceps had been profoundly anaerobic while under load. On the contrary, it appears that aerobic metabolism contributes substantially, if not completely, to energy supply. A preliminary comparison of elite sailors with

  20. Electromyographic response of global abdominal stabilizers in response to stable- and unstable-base isometric exercise.

    PubMed

    Atkins, Stephen J; Bentley, Ian; Brooks, Darrell; Burrows, Mark P; Hurst, Howard T; Sinclair, Jonathan K

    2015-06-01

    Core stability training traditionally uses stable-base techniques. Less is known as to the use of unstable-base techniques, such as suspension training, to activate core musculature. This study sought to assess the neuromuscular activation of global core stabilizers when using suspension training techniques, compared with more traditional forms of isometric exercise. Eighteen elite level, male youth swimmers (age, 15.5 ± 2.3 years; stature, 163.3 ± 12.7 cm; body mass, 62.2 ± 11.9 kg) participated in this study. Surface electromyography (sEMG) was used to determine the rate of muscle contraction in postural musculature, associated with core stability and torso bracing (rectus abdominus [RA], external obliques [EO], erector spinae [ES]). A maximal voluntary contraction test was used to determine peak amplitude for all muscles. Static bracing of the core was achieved using a modified "plank" position, with and without a Swiss ball, and held for 30 seconds. A mechanically similar "plank" was then held using suspension straps. Analysis of sEMG revealed that suspension produced higher peak amplitude in the RA than using a prone or Swiss ball "plank" (p = 0.04). This difference was not replicated in either the EO or ES musculature. We conclude that suspension training noticeably improves engagement of anterior core musculature when compared with both lateral and posterior muscles. Further research is required to determine how best to activate both posterior and lateral musculature when using all forms of core stability training.

  1. Measurement of strain and tensile force of the supraspinatus tendon under conditions that simulates low angle isometric elevation of the gleno-humeral joint: Influence of adduction torque and joint positioning.

    PubMed

    Miyamoto, Hiroki; Aoki, Mitsuhiro; Hidaka, Egi; Fujimiya, Mineko; Uchiyama, Eiichi

    2017-12-01

    Recently, supraspinatus muscle exercise has been reported to treat rotator cuff disease and to recover shoulder function. However, there have been no report on the direct measurement of strain on the supraspinatus tendon during simulated isometric gleno-humeral joint elevation. Ten fresh-frozen shoulder specimens with the rotator cuff complex left intact were used as experimental models. Isometric gleno-humeral joint elevation in a sitting position was reproduced with low angle of step-by-step elevation in the scapular plane and strain was measured on the surface layer of the supraspinatus tendon. In isometric conditions, applied tensile force of the supraspinatus tendon increased significantly with increases in adduction torque on the gleno-humeral joint. Significant increases in the strain on the layer were observed by increase in adduction torque, which were recorded in isometric elevation at -10° and 0°, but little increase in the strain was observed at 10° or greater gleno-humeral elevation. Increased strain on the surface layer of the supraspinatus tendon was observed during isometric gleno-humeral elevation from -10 to 0°. These findings demonstrate a potential risk of inducing overstretching of the supraspinatus tendon during supraspinatus muscle exercise. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Pneumatic strength assessment device: design and isometric measurement.

    PubMed

    Paulus, David C; Reiser, Raoul F; Troxell, Wade O

    2004-01-01

    In order to load a muscle optimally during resistance exercise, it should be heavily taxed throughout the entire range of motion for that exercise. However, traditional constant resistance squats only tax the lower-extremity muscles to their limits at the "sticking region" or a critical joint configuration of the exercise cycle. Therefore, a linear motion (Smith) exercise machine was modified with pneumatics and appropriate computer control so that it could be capable of adjusting force to control velocity within a repetition of the squat exercise or other exercise performed with the device. Prior to application of this device in a dynamic squat setting, the maximum voluntary isometric force (MVIF) produced over a spectrum of knee angles is needed. This would reveal the sticking region and overall variation in strength capacity. Five incremental knee angles (90, 110, 130, 150, and 170 degrees, where 180 degrees defined full extension) were examined. After obtaining university-approved informed consent, 12 men and 12 women participated in the study. The knee angle was set, and the pneumatic cylinder was pressurized such that the subject could move the barbell slightly but no more than two-centimeters. The peak pressure exerted over a five-second maximum effort interval was recorded at each knee angle in random order and then repeated. The average of both efforts was then utilized for further analysis. The sticking region occurred consistently at a 90 degrees knee angle, however, the maximum force produced varied between 110 degrees and 170 degrees with the greatest frequency at 150 degrees for both men and women. The percent difference between the maximum and minimum MVIF was 46% for men and 57% for women.

  3. 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.

  4. Plyometric training improves voluntary activation and strength during isometric, concentric and eccentric contractions.

    PubMed

    Behrens, Martin; Mau-Moeller, Anett; Mueller, Karoline; Heise, Sandra; Gube, Martin; Beuster, Nico; Herlyn, Philipp K E; Fischer, Dagmar-C; Bruhn, Sven

    2016-02-01

    This study investigated effects of plyometric training (6 weeks, 3 sessions/week) on maximum voluntary contraction (MVC) strength and neural activation of the knee extensors during isometric, concentric and eccentric contractions. Twenty-seven participants were randomly assigned to the intervention or control group. Maximum voluntary torques (MVT) during the different types of contraction were measured at 110° knee flexion (180°=full extension). The interpolated twitch technique was applied at the same knee joint angle during isometric, concentric and eccentric contractions to measure voluntary activation. In addition, normalized root mean square of the EMG signal at MVT was calculated. The twitch torque signal induced by electrical nerve stimulation at rest was used to evaluate training-related changes at the muscle level. In addition, jump height in countermovement jump was measured. After training, MVT increased by 20Nm (95% CI: 5-36Nm, P=0.012), 24Nm (95% CI: 9-40Nm, P=0.004) and 27Nm (95% CI: 7-48Nm, P=0.013) for isometric, concentric and eccentric MVCs compared to controls, respectively. The strength enhancements were associated with increases in voluntary activation during isometric, concentric and eccentric MVCs by 7.8% (95% CI: 1.8-13.9%, P=0.013), 7.0% (95% CI: 0.4-13.5%, P=0.039) and 8.6% (95% CI: 3.0-14.2%, P=0.005), respectively. Changes in the twitch torque signal of the resting muscle, induced by supramaximal electrical stimulation of the femoral nerve, were not observed, indicating no alterations at the muscle level, whereas jump height was increased. Given the fact that the training exercises consisted of eccentric muscle actions followed by concentric contractions, it is in particular relevant that the plyometric training increased MVC strength and neural activation of the quadriceps muscle regardless of the contraction mode. Copyright © 2015 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  5. Characteristics of fast voluntary and electrically evoked isometric knee extensions during 56 days of bed rest with and without exercise countermeasure

    PubMed Central

    Gerrits, K. H. L.; Rittweger, J.; Felsenberg, D.; Stegeman, D. F.; de Haan, A.

    2008-01-01

    The contractile characteristics of fast voluntary and electrically evoked unilateral isometric knee extensions were followed in 16 healthy men during 56 days of horizontal bed rest and assessed at bed rest days 4, 7, 10, 17, 24, 38 and 56. Subjects were randomized to either an inactive control group (Ctrl, n = 8) or a resistive vibration exercise countermeasure group (RVE, n = 8). No changes were observed in neural activation, indicated by the amplitude of the surface electromyogram, or the initial rate of voluntary torque development in either group during bed rest. In contrast, for Ctrl, the force oscillation amplitude at 10 Hz stimulation increased by 48% (P < 0.01), the time to reach peak torque at 300 Hz stimulation decreased by 7% (P < 0.01), and the half relaxation time at 150 Hz stimulation tended to be slightly reduced by 3% (P = 0.056) after 56 days of bed rest. No changes were observed for RVE. Torque production at 10 Hz stimulation relative to maximal (150 Hz) stimulation was increased after bed rest for both Ctrl (15%; P < 0.05) and RVE (41%; P < 0.05). In conclusion, bed rest without exercise countermeasure resulted in intrinsic speed properties of a faster knee extensor group, which may have partly contributed to the preserved ability to perform fast voluntary contractions. The changes in intrinsic contractile properties were prevented by resistive vibration exercise, and voluntary motor performance remained unaltered for RVE subjects as well. PMID:18386049

  6. Familiarization, validity and smallest detectable difference of the isometric squat test in evaluating maximal strength.

    PubMed

    Drake, David; Kennedy, Rodney; Wallace, Eric

    2018-02-06

    Isometric multi-joint tests are considered reliable and have strong relationships with 1RM performance. However, limited evidence is available for the isometric squat in terms of effects of familiarization and reliability. This study aimed to assess, the effect of familiarization, stability reliability, determine the smallest detectible difference, and the correlation of the isometric squat test with 1RM squat performance. Thirty-six strength-trained participants volunteered to take part in this study. Following three familiarization sessions, test-retest reliability was evaluated with a 48-hour window between each time point. Isometric squat peak, net and relative force were assessed. Results showed three familiarizations were required, isometric squat had a high level of stability reliability and smallest detectible difference of 11% for peak and relative force. Isometric strength at a knee angle of ninety degrees had a strong significant relationship with 1RM squat performance. In conclusion, the isometric squat is a valid test to assess multi-joint strength and can discriminate between strong and weak 1RM squat performance. Changes greater than 11% in peak and relative isometric squat performance should be considered as meaningful in participants who are familiar with the test.

  7. Eight-Week Vibration Training of the Elbow Flexors by Force Modulation: Effects on Dynamic and Isometric Strength.

    PubMed

    Xu, Lin; Cardinale, Marco; Rabotti, Chiara; Beju, Bogdan; Mischi, Massimo

    2016-03-01

    Vibration exercise (VE) has been suggested as an effective method to improve strength and power capabilities. However, the underlying mechanisms in response to VE are still unclear. A pulley-like VE system, characterized by sinusoidal force applications has been developed and tested for proof of concept in a previous study. The aim of this study was to evaluate the effects of such force modulation on elbow flexors strength and compare it with conventional methods. Forty subjects were randomly divided into 4 groups of 10: the vibration group (VG), the no-vibration group (NVG), the dumbbell group (DG), and the control group (CG). Biceps curl exercises were used to train the elbow flexors 2 times a week for 8 weeks. Subjects in the VG were trained using a ramp-up baseline with superimposed 30 Hz sinusoidal vibration whereas the subjects in the NVG were trained using the same baseline but without vibration. Subjects in the DG were trained using dumbbells, and the subjects in the CG were not trained. The isometric break force (IBF) and 1 repetition maximum (1RM) of the subject's dominant arm were assessed before and after the 8-week training period. The VG achieved 1RM improvement (22.7%) larger than the NVG (10.8%) and comparable with the DG (22.3%). Differences in IBF gains following the training period among the training groups were found to be not significant. Our results support the inclusion of the proposed VE in strength training programs aimed at improving dynamic strength on the elbow flexors.

  8. Selective activation of the latissimus dorsi and the inferior fibers of trapezius at various shoulder angles during isometric pull-down exertion.

    PubMed

    Park, Se-yeon; Yoo, Won-gyu

    2013-12-01

    The aim of this study was to determine the effect of isometric pull down exercise on muscle activity with shoulder elevation angles of 60°, 90°, and 120° and sagittal, scapular, and frontal movement planes, by electromyography (EMG) of the latissimus dorsi, inferior fibers of trapezius, and latissimus dorsi/inferior fibers of trapezius activity ratio. Fourteen men performed nine conditions of isometric pull down exercise (three conditions of shoulder elevation × three conditions of movement planes). Surface EMG was used to collect data from the latissimus dorsi and inferior fibers of trapezius during exercise. Two-way repeated analysis of variance with two within-subject factors (shoulder elevation angles and planes of movement) was used to determine the significance of the latissimus dorsi and inferior fibers of trapezius activity and latissimus dorsi/inferior fibers of trapezius activity ratio. The latissimus dorsi activity and ratio between the latissimus dorsi and the inferior fibers of trapezius were significantly decreased as shoulder elevation angle increased from 60° to 120°. The inferior fibers of trapezius activity was significantly increased with shoulder elevation angle. The EMG activity and the ratios were not affected by changes in movement planes. This study suggests that selective activation of the latissimus dorsi is accomplished with a low shoulder elevation angle, while the inferior fibers of the trapezius are activated with high shoulder elevation angles. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. Effects of Training on the Estimation of Muscular Moment in Submaximal Exercise

    ERIC Educational Resources Information Center

    Leverrier, Celine; Gauthier, Antoine; Nicolas, Arnaud; Molinaro, Corinne

    2011-01-01

    The purpose of this study was to observe the effects of a submaximal isometric training program on estimation capacity at 25, 50, and 75% of maximal contraction in isometric action and at two angular velocities. The second purpose was to study the variability of isometric action. To achieve these purposes, participants carried out an isokinetic…

  10. Relative Activity of Abdominal Muscles during Commonly Prescribed Strengthening Exercises.

    ERIC Educational Resources Information Center

    Willett, Gilbert M.; Hyde, Jennifer E.; Uhrlaub, Michael B.; Wendel, Cara L.; Karst, Gregory M.

    2001-01-01

    Examined the relative electromyographic (EMG) activity of upper and lower rectus abdominis (LRA) and external oblique (EOA) muscles during five abdominal strengthening exercises. Isometric and dynamic EMG data indicated that abdominal strengthening exercises activated various abdominal muscle groups. For the LRA and EOA muscle groups, there were…

  11. Effects of a Short-Term High-Nitrate Diet on Exercise Performance

    PubMed Central

    Porcelli, Simone; Pugliese, Lorenzo; Rejc, Enrico; Pavei, Gaspare; Bonato, Matteo; Montorsi, Michela; La Torre, Antonio; Rasica, Letizia; Marzorati, Mauro

    2016-01-01

    It has been reported that nitrate supplementation can improve exercise performance. Most of the studies have used either beetroot juice or sodium nitrate as a supplement; there is lack of data on the potential ergogenic benefits of an increased dietary nitrate intake from a diet based on fruits and vegetables. Our aim was to assess whether a high-nitrate diet increases nitric oxide bioavailability and to evaluate the effects of this nutritional intervention on exercise performance. Seven healthy male subjects participated in a randomized cross-over study. They were tested before and after 6 days of a high (HND) or control (CD) nitrate diet (~8.2 mmol∙day−1 or ~2.9 mmol∙day−1, respectively). Plasma nitrate and nitrite concentrations were significantly higher in HND (127 ± 64 µM and 350 ± 120 nM, respectively) compared to CD (23 ± 10 µM and 240 ± 100 nM, respectively). In HND (vs. CD) were observed: (a) a significant reduction of oxygen consumption during moderate-intensity constant work-rate cycling exercise (1.178 ± 0.141 vs. 1.269 ± 0.136 L·min−1); (b) a significantly higher total muscle work during fatiguing, intermittent sub-maximal isometric knee extension (357.3 ± 176.1 vs. 253.6 ± 149.0 Nm·s·kg−1); (c) an improved performance in Repeated Sprint Ability test. These findings suggest that a high-nitrate diet could be a feasible and effective strategy to improve exercise performance. PMID:27589795

  12. A mathematical model of forces in the knee under isometric quadriceps contractions.

    PubMed

    Huss, R A; Holstein, H; O'Connor, J J

    2000-02-01

    To predict the knee's response to isometric quadriceps contractions against a fixed tibial restraint.Design. Mathematical modelling of the human knee joint. Isometric quadriceps contraction is commonly used for leg muscle strengthening following ligament injury or reconstruction. It is desirable to know the ligament forces induced but direct measurement is difficult. The model, previously applied to the Lachmann or 'drawer' tests, combines an extensible fibre-array representation of the cruciate ligaments with a compressible 'thin-layer' representation of the cartilage. The model allows the knee configuration and force system to be calculated, given flexion angle, restraint position and loading. Inclusion of cartilage deformation increases relative tibio-femoral translation and decreases the ligament forces generated. For each restraint position, a range of flexion angles is found in which no ligament force is required, as opposed to a single flexion angle in the case of incompressible cartilage layers. Knee geometry and ligament elasticity are found to be the most important factors governing the joint's response to isometric quadriceps contractions, but cartilage deformation is found to be more important than in the Lachmann test. Estimation of knee ligament forces is important when devising exercise regimes following ligament injury or reconstruction. The finding of a 'neutral zone' of zero ligament force may have implications for rehabilitation of the ligament-injured knee.

  13. Neuromuscular fatigue following isometric contractions with similar torque time integral.

    PubMed

    Rozand, V; Cattagni, T; Theurel, J; Martin, A; Lepers, R

    2015-01-01

    Torque time integral (TTI) is the combination of intensity and duration of a contraction. The aim of this study was to compare neuromuscular alterations following different isometric sub-maximal contractions of the knee extensor muscles but with similar TTI. Sixteen participants performed 3 sustained contractions at different intensities (25%, 50%, and 75% of Maximal Voluntary Contraction (MVC) torque) with different durations (68.5±33.4 s, 35.1±16.8 s and 24.8±12.9 s, respectively) but similar TTI value. MVC torque, maximal voluntary activation level (VAL), M-wave characteristics and potentiated doublet amplitude were assessed before and immediately after the sustained contractions. EMG activity of the vastus lateralis (VL) and -rectus femoris (RF) muscles was recorded during the sustained contractions. MVC torque reduction was similar in the 3 conditions after the exercise (-23.4±2.7%). VAL decreased significantly in a similar extent (-3.1±1.3%) after the 3 sustained contractions. Potentiated doublet amplitude was similarly reduced in the 3 conditions (-19.7±1.5%), but VL and RF M-wave amplitudes remained unchanged. EMG activity of VL and RF muscles increased in the same extent during the 3 contractions (VL: 54.5±40.4%; RF: 53.1±48.7%). These results suggest that central and peripheral alterations accounting for muscle fatigue are similar following isometric contractions with similar TTI. TTI should be considered in the exploration of muscle fatigue during sustained isometric contractions. © Georg Thieme Verlag KG Stuttgart · New York.

  14. An investigation of the tri-bar gripping system on isometric muscular endurance.

    PubMed

    Drury, Daniel G; Faggiono, Heath; Stuempfle, Kristin J

    2004-11-01

    Recently, a new product called the Tri-Bar has been introduced as an alternative to the standard round weightlifting bar. The Tri-Bar has the same weight, length, and circumference as a standard weightlifting bar and differs only in that the shape of the bar is formed like a triangle with rounded edges. Theoretically, the shape of the bar will enhance gripping comfort and increase muscular endurance. We studied 32 moderately trained males who were free from upper-body injury or limitation. Each participant completed 4 visits to the lab as part of 2 separate investigations. The first investigation was a comparison of straight-arm hang times while grasping a standard Olympic bar or a Tri-Bar attached to the top of a power rack. The second investigation involved grasping a standard revolving cable handle or a Tri-Bar revolving handle attached to a weight equal to half the subject's body weight. In both investigations, time was used as a measure of isometric muscular endurance. Differences were determined using a dependent t-test, and a level of significance was set at p < 0.05. Mean hang times were significantly longer when the men hung from the Tri-Bar (107.6 seconds) versus the standard bar (95.4 seconds) (p = 0.015). Conversely, in the investigation using the revolving handles, the round bar produced longer grasping times (71.5 seconds) than the Tri-Bar (62.6 seconds) (p = 0.000). The results of this investigation indicate that a fixed and stable Tri-Bar may help to increase hang time, but a Tri-Bar free to rotate within the grasp may decrease grasping time in comparison to a standard round handle. With regard to exercises that require isometric grasping, the Tri-Bar may be an effective alternative to the standard bar for increasing isometric grasping endurance.

  15. Abnormal Neurocirculatory Control During Exercise in Humans with Chronic Renal Failure

    PubMed Central

    Park, Jeanie; Middlekauff, Holly R.

    2014-01-01

    Abnormal neurocirculatory control during exercise is one important mechanism leading to exercise intolerance in patients with both end-stage renal disease (ESRD) and earlier stages of chronic kidney disease (CKD). This review will provide an overview of mechanisms underlying abnormal neurocirculatory and hemodynamic responses to exercise in patients with kidney disease. Recent studies have shown that ESRD and CKD patients have an exaggerated increase in blood pressure (BP) during both isometric and rhythmic exercise. Subsequent studies examining the role of the exercise pressor reflex in the augmented pressor response revealed that muscle sympathetic nerve activity (MSNA) was not augmented during exercise in these patients, and metaboreflex-mediated increases in MSNA were blunted, while mechanoreflex-mediated increases were preserved under basal conditions. However, normalizing the augmented BP response during exercise via infusion of nitroprusside (NTP), and thereby equalizing baroreflex-mediated suppression of MSNA, an important modulator of the final hemodynamic response to exercise, revealed that CKD patients had an exaggerated increase in MSNA during isometric and rhythmic exercise. In addition, mechanoreflex-mediated control was augmented, and metaboreceptor blunting was no longer apparent in CKD patients with baroreflex normalization. Factors leading to mechanoreceptor sensitization, and other mechanisms underlying the exaggerated exercise pressor response, such as impaired functional sympatholysis, should be investigated in future studies. PMID:25458430

  16. Effects of Lumbar Strengthening Exercise in Lower-Limb Amputees With Chronic Low Back Pain.

    PubMed

    Shin, Min Kyung; Yang, Hee Seung; Yang, Hea-Eun; Kim, Dae Hyun; Ahn, Bo Ram; Kwon, Hyup; Lee, Ju Hwan; Jung, Suk; Choi, Hyun Chul; Yun, Sun Keaung; Ahn, Dong Young; Sim, Woo Sob

    2018-02-01

    To analyze the effect of lumbar strengthening exercise in lower-limb amputees with chronic low back pain. We included in this prospective study 19 lower-limb amputees who had experienced low back pain for longer than 6 months. Participants were treated with 30-minute lumbar strengthening exercises, twice weekly, for 8 weeks. We used the visual analog scale (VAS), and Oswestry low back pain disability questionnaire, and measured parameters such as iliopsoas length, abdominal muscle strength, back extensor strength, and back extensor endurance. In addition, we assessed the isometric peak torque and total work of the trunk flexors and extensors using isokinetic dynamometer. The pre- and post-exercise measurements were compared. Compared with the baseline, abdominal muscle strength (from 4.4±0.7 to 4.8±0.6), back extensor strength (from 2.6±0.6 to 3.5±1.2), and back extensor endurance (from 22.3±10.7 to 46.8±35.1) improved significantly after 8 weeks. The VAS decreased significantly from 4.6±2.2 to 2.6±1.6 after treatment. Furthermore, the peak torque and total work of the trunk flexors and extensors increased significantly (p<0.05). Lumbar strengthening exercise in lower-limb amputees with chronic low back pain resulted in decreased pain and increased lumbar extensor strength. The lumbar strengthening exercise program is very effective for lower-limb amputees with chronic low back pain.

  17. Children with Heavy Prenatal Alcohol Exposure have Different Frequency Domain Signal Characteristics when Producing Isometric Force

    PubMed Central

    Nguyen, Tanya T.; Ashrafi, Ashkan; Thomas, Jennifer D.; Riley, Edward P.; Simmons, Roger W.

    2013-01-01

    To extend our current understanding of the teratogenic effects of prenatal alcohol exposure on the control of isometric force, the present study investigated the signal characteristics of power spectral density functions resulting from sustained control of isometric force by children with and without heavy prenatal exposure to alcohol. It was predicted that the functions associated with the force signals would be fundamentally different for the two groups. Twenty-five children aged between 7 and 17 years with heavy prenatal alcohol exposure and 21 non-alcohol exposed control children attempted to duplicate a visually represented target force by pressing on a load cell. The level of target force (5 and 20% of maximum voluntary contraction) and the time interval between visual feedback (20ms, 320ms and 740ms) were manipulated. A multivariate spectral estimation method with sinusoidal windows was applied to individual isometric force-time signals. Analysis of the resulting power spectral density functions revealed that the alcohol-exposed children had a lower mean frequency, less spectral variability, greater peak power and a lower frequency at which peak power occurred. Furthermore, mean frequency and spectral variability produced by the alcohol-exposed group remained constant across target load and visual feedback interval, suggesting that these children were limited to making long-time scale corrections to the force signal. In contrast, the control group produced decreased mean frequency and spectral variability as target force and the interval between visual feedback increased, indicating that when feedback was frequently presented these children used the information to make short-time scale adjustments to the ongoing force signal. Knowledge of these differences could facilitate the design of motor rehabilitation exercises that specifically target isometric force control deficits in alcohol-exposed children. PMID:23238099

  18. Effect of age and gender on the surface electromyogram during various levels of isometric contraction.

    PubMed

    Arjunan, Sridhar; Kumar, Dinesh; Kalra, Chandan; Burne, John; Bastos, Teodiano

    2011-01-01

    This study reports the effects of age and gender on the surface electromyogram while performing isometric contraction. Experiments were conducted with two age groups--Young (Age: 20-29) and Old (Age: 60-69) where they performed sustained isometric contractions at various force levels (50%, 75%, 100% of maximum voluntary contraction). Traditional features such as root mean square (RMS) and median frequency (MDF) were computed from the recorded sEMG. The result indicates that the MDF of sEMG was not significantly affected by age, but was impacted by gender in both age groups. Also there was a significant change in the RMS of sEMG with age and gender at all levels of contraction. The results also indicate a large inter-subject variation. This study will provide an understanding of the underlying physiological effects of muscle contraction and muscle fatigue in different cohorts.

  19. Effectiveness of home exercise on pain, function, and strength of manual wheelchair users with spinal cord injury: a high-dose shoulder program with telerehabilitation.

    PubMed

    Van Straaten, Meegan G; Cloud, Beth A; Morrow, Melissa M; Ludewig, Paula M; Zhao, Kristin D

    2014-10-01

    To test the effectiveness of a high-dose home exercise/telerehabilitation program for manual wheelchair users who have a spinal cord injury (SCI) by determining whether the intervention would reduce pain and increase function, as we hypothesized. A pre-post trial with outcomes measured at 3 time points: baseline, postintervention (12wk), and follow-up (>24 wk). Subjects performed an exercise program at their homes using telerehabilitation for therapist monitoring of technique and exercise advancement. Baseline and postintervention data were collected at a motion analysis laboratory in a tertiary medical center. A convenience sample of manual wheelchair users (N=16, 3 women; average age, 41y; average time in a wheelchair, 16y) with shoulder pain (average pain duration, 9y) and mechanical impingement signs on physical examination. A 12-week home exercise program of rotator cuff and scapular stabilization exercises was given to each participant. The program included a high dose of 3 sets of 30 repetitions, 3 times weekly, and regular physical therapist supervision via videoconferencing. Primary outcomes of pain and function were measured with the Wheelchair User's Shoulder Pain Index (WUSPI), Disabilities of Arm, Shoulder, and Hand (DASH) Index, and Shoulder Rating Questionnaire (SRQ). Secondary outcomes of strength were measured with isometric strength tests of scapulothoracic and glenohumeral muscles, and a static fatigue test of the lower trapezius. Pain was reduced and function improved after the intervention. There was a significant main effect for pain and function between the 3 time points based on the Friedman signed-ranked test, WUSPI (χ(2)2=5.10, P=.014), DASH Index (χ(2)2=5.41, P=.012), and SRQ (χ(2)2=23.71, P≤.001). Wilcoxon signed-rank tests demonstrated that isometric strength measurements of the serratus anterior and scapular retractors increased after the exercise intervention ([t=2.42, P=.04] and [t=4.67, P=.003], respectively). Muscle impulse

  20. Effects of an exercise programme on self-esteem, self-concept and quality of life in women with fibromyalgia: a randomized controlled trial.

    PubMed

    García-Martínez, Aida M; De Paz, José A; Márquez, Sara

    2012-07-01

    This study was aimed to investigate the effects of an exercise trial on self-esteem, self-concept and quality of life in patients with fibromyalgia and to evaluate whether improvements in psychological distress were related to changes in physical functioning. Twenty-eight women with a primary diagnosis of fibromyalgia were randomized to a usual care control group or to a 12-week supervised training programme consisting of 3 weekly sessions of aerobic, strengthening and flexibility exercises. Outcomes were physical functioning (Fibromyalgia Impact Questionnaire (FIQ), lower-body strength and flexibility) and psychological functioning (SF-36, Rosenberg self-esteem scale and Erdmann self-concept scale). Outcomes were measured at study entry and at the end of the intervention. Compared to the control group, statistically significant improvements in self-esteem, self-concept, FIQ, physical functioning, role physical, bodily pain, vitality, role emotional, social functioning, mental health, isometric strength, muscular endurance and flexibility were evident in the exercise group at the end of treatment. Self-esteem and self-concept scores were correlated positively with role emotional, mental health and the mental component summary of SF-36 and were negatively correlated to FIQ scores. No significant correlation existed between self-esteem or self-concept and isometric strength, muscular endurance or flexibility. Our results highlight the need for a broader array of physical and mental outcomes and the importance of examining patient's perceptions in future research therapies.

  1. The role of exercise in migraine treatment.

    PubMed

    Koseoglu, E; Yetkin, M F; Ugur, F; Bilgen, M

    2015-09-01

    This review aims to provide a comprehensive overview of the literature on the use of exercise for migraine treatment with regard to its efficacy, mechanism of action and role in practice. Many randomized studies have reported the efficacy of prophylactic treatment of migrane with medications such as beta blockers or antiepileptic drugs. Studies on alternative approaches, like aerobic exercise and biofeedback, are however limited but also considered to be effective. Scientific databases were searched with keywords "exercise" and "migraine". The resulting publications were gathered, examined and discussed throughly. Past studies had limitations and were few in number, but more recent randomized controlled studies have concretely provided level of evidence about the effectiveness of exercise in prophylactic treatment of migraine. Core properties of exercise like intensity, duration, frequency, type and warming up period are required to be monitored while treating migraine to increase the beneficial effects and, also to prevent injuries and side effects which may include exertional headache. Isometric neck exercise is helpful when the migraine is accompanied by neck pain. Patient population with low beta endorphin level in blood, high physical fitness and high motivation receives significant benefits from the exercise treatment. The action of exercise on migraine is in general related to neurochemical factors, psychological states and increase in cardivascular and cerebrovascular fitness. Considering its effectiveness and minimal side effects, migraine patients should often be encouraged to practice physical exercise with intensity, frequency and duration that should be carefully instituted to achieve the most beneficial outcome while preventing potential injuries and side effects.

  2. Exercise training for blood pressure: a systematic review and meta-analysis.

    PubMed

    Cornelissen, Veronique A; Smart, Neil A

    2013-02-01

    We conducted meta-analyses examining the effects of endurance, dynamic resistance, combined endurance and resistance training, and isometric resistance training on resting blood pressure (BP) in adults. The aims were to quantify and compare BP changes for each training modality and identify patient subgroups exhibiting the largest BP changes. Randomized controlled trials lasting ≥4 weeks investigating the effects of exercise on BP in healthy adults (age ≥18 years) and published in a peer-reviewed journal up to February 2012 were included. Random effects models were used for analyses, with data reported as weighted means and 95% confidence interval. We included 93 trials, involving 105 endurance, 29 dynamic resistance, 14 combined, and 5 isometric resistance groups, totaling 5223 participants (3401 exercise and 1822 control). Systolic BP (SBP) was reduced after endurance (-3.5 mm Hg [confidence limits -4.6 to -2.3]), dynamic resistance (-1.8 mm Hg [-3.7 to -0.011]), and isometric resistance (-10.9 mm Hg [-14.5 to -7.4]) but not after combined training. Reductions in diastolic BP (DBP) were observed after endurance (-2.5 mm Hg [-3.2 to -1.7]), dynamic resistance (-3.2 mm Hg [-4.5 to -2.0]), isometric resistance (-6.2 mm Hg [-10.3 to -2.0]), and combined (-2.2 mm Hg [-3.9 to -0.48]) training. BP reductions after endurance training were greater (P<0.0001) in 26 study groups of hypertensive subjects (-8.3 [-10.7 to -6.0]/-5.2 [-6.8 to -3.4] mm Hg) than in 50 groups of prehypertensive subjects (-2.1 [-3.3 to -0.83]/-1.7 [-2.7 to -0.68]) and 29 groups of subjects with normal BP levels (-0.75 [-2.2 to +0.69]/-1.1 [-2.2 to -0.068]). BP reductions after dynamic resistance training were largest for prehypertensive participants (-4.0 [-7.4 to -0.5]/-3.8 [-5.7 to -1.9] mm Hg) compared with patients with hypertension or normal BP. Endurance, dynamic resistance, and isometric resistance training lower SBP and DBP, whereas combined training lowers only DBP. Data from a small

  3. The effect of active core exercise on fitness and foot pressure in Taekwondo club students.

    PubMed

    Yoon, Seong-Deok; Sung, Dong-Hun; Park, Gi Duck

    2015-02-01

    [Purpose] The effects of core training using slings and Togus on the improvement of posture control in Taekwondo club students, that is, balance ability, were investigated. To that end, changes in the Taekwondo players' balance ability resulting from active core training for eight weeks were examined through fitness and foot pressure. [Subjects] The present study was conducted with 13 male Taekwondo players of K University in Deagu, South Korea. Once the experiment process was explained, consent was obtained from those who participated voluntarily. [Methods] Air cushions (Germany), Jumpers (Germany), and Aero-Steps (Germany) were used as lumbar stabilization exercise tools. As a method of training proprioceptive senses by stimulating somatesthesia in standing postures, the subjects performed balance squats, supine pelvic lifts, and push-up plus exercise using slings while standing on an Aero-Step and performed hip extension parallel squats (Wall Gym Ball), and standing press-ups on a Togu using their own weight. The subjects performed four sets of these isometric exercises while maintaining an exercise time per set at 30 seconds in each session and repeated this session three times per week. [Result] Left grip strength significantly increased and number of sit-ups, which indicates muscle endurance, also significantly increased after the eight weeks exercise compared with before the exercise. The values measured during the sit and reach test, which indicate flexibility, also significantly increase after the eight weeks of exercise compared with before the exercise but only in the left foot. [Conclusion] The result of present study suggest that active core exercise using Slings and Togus can be applied as a very effective exercise program for enhancing balance, which is an important physical factor for Taekwondo club students.

  4. Electromyographic Analysis of Single-Leg, Closed Chain Exercises: Implications for Rehabilitation After Anterior Cruciate Ligament Reconstruction

    PubMed Central

    Beutler, Anthony I.; Cooper, Leslie W.; Kirkendall, Don T.; Garrett, William E.

    2002-01-01

    Objective: Many knee rehabilitation studies have examined open and closed kinetic chain exercises. However, most studies focus on 2-legged, closed chain exercise. The purpose of our study was to characterize 1-legged, closed chain exercise in young, healthy subjects. Subjects: Eighteen normal subjects (11 men, 7 women; age, 24.6 ± 1.6 years) performed unsupported, 1-legged squats and step-ups to approximately tibial height. Measurements: Knee angle data and surface electromyographic activity from the thigh muscles were recorded. Results: The maximum angle of knee flexion was 111 ± 23° for squats and 101 ± 16° for step-ups. The peak quadriceps activation was 201 ± 66% maximum voluntary isometric contraction, occurring at an angle of 96 ± 16° for squats. Peak quadriceps activation was 207 ± 50% maximum voluntary isometric contraction and occurred at 83 ± 12° for step-ups. Conclusions: The high and sustained levels of quadriceps activation indicate that 1-legged squats and step-ups would be effective in muscle rehabilitation. As functional, closed chain activities, they may also be protective of anterior cruciate ligament grafts. Because these exercises involve no weights or training equipment, they may prove more cost effective than traditional modes of rehabilitation. PMID:12937438

  5. Isometric and swallowing tongue strength in healthy adults.

    PubMed

    Todd, J Tee; Lintzenich, Catherine Rees; Butler, Susan G

    2013-10-01

    The tongue contributes to a safe swallow. It facilitates bolus control during mastication, maintains a bolus in the oral cavity to prevent premature entry of the bolus into the hypopharynx, and helps generate pressure in the hypopharynx during swallowing. This study examined isometric tongue strength and tongue pressure measured during swallowing in healthy young and older adults. Prospective group design. One hundred twenty-six healthy individuals who were recruited as part of a larger study on swallowing participated in this study. Participants were divided into three age groups: 20 to 40 years, 41 to 60 years, and ≥61 years. A KayPentax Digital Swallowing Workstation with an air-filled bulb array was placed on the tongue of each participant (anterior to posterior). Participants completed three isometric tongue presses and three swallows. Repeated measures analyses of variance revealed a significant main effect of age (P = .01) and gender by tongue bulb location interaction (P = .02) for isometric tongue strength. That is, older adults had lower isometric tongue strength than young adults, and females had a greater difference between anterior and posterior tongue strength than males. Tongue strength during swallowing yielded significantly greater anterior versus posterior tongue pressure. This study comprises one of the largest in terms of number of healthy participants reported to date and confirms previous findings that isometric tongue strength decreases with age. Furthermore, given young and older adults generate similar swallowing pressures, swallowing is a submaximal strength activity, yet older adults have less functional reserve. 4. Copyright © 2013 The American Laryngological, Rhinological, and Otological Society, Inc.

  6. A Comparison of Exercise-Induced Muscle Damage Following Maximal Eccentric Contractions in Men and Boys.

    PubMed

    Deli, Chariklia K; Fatouros, Ioannis G; Paschalis, Vassilis; Georgakouli, Kalliopi; Zalavras, Athanasios; Avloniti, Alexandra; Koutedakis, Yiannis; Jamurtas, Athanasios Z

    2017-08-01

    Research regarding exercise-induced muscle-damage mainly focuses on adults. The present study examined exercise-induced muscle-damage responses in adults compared with children. Eleven healthy boys (10-12 y) and 15 healthy men (18-45 y) performed 5 sets of 15 maximal eccentric contractions of the knee extensors. Range of motion (ROM), delayed onset muscle soreness (DOMS) during squat and walking, and peak isometric, concentric and eccentric torque were assessed before, post, 24, 48, 72, and 96 hr postexercise. Creatine kinase (CK) activity was assessed before and 72 hr postexercise. Eccentric exercise resulted in DOMS during squat that persisted for up to 96h in men, and 48 hr in boys (p < .05), and DOMS during walking that persisted for up to 72 hr in men, and 48 hr in boys (p < .01). The ROM was lower in both age groups 48 hr postexercise (p < .001). Isometric (p < .001), concentric (p < .01) and eccentric (p < .01) force decreased post, and up to 48 hr postexercise in men. Except for a reduction in isometric force immediately after exercise, no other changes occurred in boys' isokinetic force. CK activity increased in men at 72 hr postexercise compared with pre exercise levels (p = .05). Our data provide further confirmation that children are less susceptible to exercise-induced muscle damage compared with adults.

  7. Effect of dietary nitrate supplementation on tolerance to supramaximal intensity intermittent exercise.

    PubMed

    Aucouturier, Julien; Boissière, Julien; Pawlak-Chaouch, Mehdi; Cuvelier, Grégory; Gamelin, François-Xavier

    2015-09-15

    Dietary nitrate (NO3(-)) supplementation has been shown to increase exercise tolerance and improve oxidative efficiency during aerobic exercise in healthy subjects. We tested the hypothesis that a 3-day supplementation in beetroot juice (BJ) rich in NO3(-) would improve the tolerance to supramaximal intensity intermittent exercise consisting of 15-s exercise periods at 170% of the maximal aerobic power interspersed with 30-s passive recovery periods. The number of repetitions completed before reaching volitional exhaustion was significantly higher in the BJ than in the placebo condition (26.1 ± 10.7 versus 21.8 ± 8.0 respectively, P < 0.05). In contrast to previous findings during exercise performed at intensity below the peak oxygen uptake (VO2peak), oxygen uptake (VO2) was unaffected (BJ: 2735 ± 345 mL kg(-1) min(-1) vs. placebo: 2787 ± 346 mL kg(-1) min(-1), NS). However, the Area Under the Curve for microvascular total hemoglobin (AUC-THb) in the vastus lateralis muscle assessed by near infrared spectroscopy during 3 time-matched repetitions was significantly increased with NO3(-) supplementation (BJ: 9662 ± 1228 a.u. vs. placebo:8178 ± 1589 a.u.; P < 0.05). Thus, increased NO3(-) (BJ: 421.5 ± 107.4 μM vs placebo:39.4 ± 18.0 μM) and NO2(-) (BJ: 441 ± 184 nM vs placebo: 212 ± 119 nM) plasma levels (P < 0.001 for both) are associated with improved muscle microvascular Red Blood Cell (RBC) concentration and O2 delivery during intense exercise, despite no effect on resting femoral artery blood flow, and vascular conductance. Maximal voluntary force during an isometric leg extensor exercise, and blood lactate levels were also unaffected by NO3(-) supplementation. To conclude, dietary NO3(-) supplementation enhances tolerance to exercise at supramaximal intensity, with increased microvascular total RBC concentration in the working muscle, in the absence of effect on contractile function and resting hemodynamic parameters. Copyright © 2015 Elsevier Inc

  8. Effect of Acute Effort on Isometric Strength and Body Balance: Trained vs. Untrained Paradigm.

    PubMed

    Sterkowicz, Stanisław; Jaworski, Janusz; Lech, Grzegorz; Pałka, Tomasz; Sterkowicz-Przybycień, Katarzyna; Bujas, Przemysław; Pięta, Paweł; Mościński, Zenon

    2016-01-01

    Years of training in competitive sports leads to human body adaptation to a specific type of exercise. In judo bouts, maintaining hand grip on an opponent's clothes and postural balance is essential for the effective technical and tactical actions. This study compares changes after maximal anaerobic exercise among judo athletes and untrained subjects regarding 1) maximum isometric handgrip strength (HGSmax) and accuracy at the perceived 50% maximum handgrip force (1/2HGSmax) and 2) the balance of 13 judo athletes at national (n = 8) and international (n = 5) competitive levels and 19 untrained university students. The groups did not differ in age, body height, and weight. Body mass index (BMI) and body composition (JAWON) were evaluated. The Wingate Anaerobic Test (WAnT, Monark 875E) measured recommended anaerobic capacity indices. Hand grip strength (Takei dynamometer) and balance (biplate balance platform) were measured before warm-up (T1), before the WAnT test (T2), and after (T3). Parametric or non-parametric tests were performed after verifying the variable distribution assumption. Judoists had higher BMI and fat-free mass index (FFMI) than the students. The athletes also showed higher relative total work and relative peak power and lower levels of lactic acid. The difference in judoists between HGSmax at T1 and HGSmax at T3 was statistically significant. Before warm-up (T1), athletes showed higher strength (more divergent from the calculated ½HGSmax value) compared to students. Substantial fatigue after the WAnT test significantly deteriorated the body stability indices, which were significantly better in judo athletes at all time points. The findings suggest specific body adaptations in judoists, especially for body composition, anaerobic energy system efficiency, and postural balance. These characteristics could be trained for specifically by judo athletes to meet the time-motion and anaerobic demands of contemporary bouts.

  9. Effect of Acute Effort on Isometric Strength and Body Balance: Trained vs. Untrained Paradigm

    PubMed Central

    Sterkowicz, Stanisław; Jaworski, Janusz; Lech, Grzegorz; Pałka, Tomasz; Sterkowicz-Przybycień, Katarzyna; Bujas, Przemysław; Pięta, Paweł; Mościński, Zenon

    2016-01-01

    Years of training in competitive sports leads to human body adaptation to a specific type of exercise. In judo bouts, maintaining hand grip on an opponent’s clothes and postural balance is essential for the effective technical and tactical actions. This study compares changes after maximal anaerobic exercise among judo athletes and untrained subjects regarding 1) maximum isometric handgrip strength (HGSmax) and accuracy at the perceived 50% maximum handgrip force (1/2HGSmax) and 2) the balance of 13 judo athletes at national (n = 8) and international (n = 5) competitive levels and 19 untrained university students. The groups did not differ in age, body height, and weight. Body mass index (BMI) and body composition (JAWON) were evaluated. The Wingate Anaerobic Test (WAnT, Monark 875E) measured recommended anaerobic capacity indices. Hand grip strength (Takei dynamometer) and balance (biplate balance platform) were measured before warm-up (T1), before the WAnT test (T2), and after (T3). Parametric or non-parametric tests were performed after verifying the variable distribution assumption. Judoists had higher BMI and fat-free mass index (FFMI) than the students. The athletes also showed higher relative total work and relative peak power and lower levels of lactic acid. The difference in judoists between HGSmax at T1 and HGSmax at T3 was statistically significant. Before warm-up (T1), athletes showed higher strength (more divergent from the calculated ½HGSmax value) compared to students. Substantial fatigue after the WAnT test significantly deteriorated the body stability indices, which were significantly better in judo athletes at all time points. The findings suggest specific body adaptations in judoists, especially for body composition, anaerobic energy system efficiency, and postural balance. These characteristics could be trained for specifically by judo athletes to meet the time-motion and anaerobic demands of contemporary bouts. PMID:27218258

  10. Inhibition of xanthine oxidase reduces oxidative stress and improves skeletal muscle function in response to electrically stimulated isometric contractions in aged mice

    PubMed Central

    Ryan, Michael J.; Jackson, Janna R.; Hao, Yanlei; Leonard, Stephen S.; Alway, Stephen E.

    2012-01-01

    Oxidative stress is a putative factor responsible for reducing function and increasing apoptotic signaling in skeletal muscle with aging. This study examined the contribution and functional significance of the xanthine oxidase enzyme as a potential source of oxidant production in aged skeletal muscle during repetitive in situ electrically stimulated isometric contractions. Xanthine oxidase activity was inhibited in young adult and aged mice via a subcutaneously placed time release (2.5 mg/day) allopurinol pellet, 7 days prior to the start of in situ electrically stimulated isometric contractions. Gastrocnemius muscles were electrically activated with 20 maximal contractions for three consecutive days. Xanthine oxidase activity was 65% greater in the gastrocnemius muscle of aged mice compared to young mice. Xanthine oxidase activity also increased after in situ electrically stimulated isometric contractions in muscles from both young (33%) and aged (28%) mice, relative to contralateral non-contracted muscles. Allopurinol attenuated the exercise-induced increase in oxidative stress, but it did not affect the elevated basal levels of oxidative stress that was associated with aging. In addition, inhibition of xanthine oxidase activity decreased caspase 3 activity, but it had no effect on other markers of mitochondrial associated apoptosis. Our results show that compared to control conditions, suppression of xanthine oxidase activity by allopurinol reduced xanthine oxidase activity, H2O2 levels, lipid peroxidation and caspase-3 activity, prevented the in situ electrically stimulated isometric contraction-induced loss of glutathione, prevented the increase of catalase and copper-zinc superoxide dismutase activities, and increased maximal isometric force in the plantar flexor muscles of aged mice after repetitive electrically evoked contractions. PMID:21530649

  11. Development of exercise devices to minimize musculoskeletal and cardiovascular deconditioning in microgravity

    NASA Technical Reports Server (NTRS)

    Schwandt, Douglas F.; Whalen, Robert T.; Watenpaugh, Donald E.; Parazynski, Scott E.; Hargens, Alan R.

    1991-01-01

    The paper describes three exercise devices, developed at the NASA-Ames Research Center, for maintaining musculoskeletal and cardiovascular fitness in astronauts during extended space flights. These devices represent the following exercise concepts: (1) exercise against LBNP, (2) instrumented dynamic interlimb resistance, and (3) multiple resistive exercise. The three devices complement each other to provide the aerobic and strength training exercises for different situations. All three devices permit eccentric, concentric, and isometric contractions for a variety of exercises.

  12. Exercise in the healthy older adult.

    PubMed

    Karani, R; McLaughlin, M A; Cassel, C K

    2001-01-01

    Habitual exercise provides numerous health benefits to the older adult. While dynamic aerobic activities increase stamina and lung capacity, isometric or resistance training improves muscle strength and endurance. Long-term benefits of continued exercise include a decreased risk of death from heart disease, enhanced balance and mobility, a decreased risk of diabetes, and an improvement in depressive symptoms. While the hazards of exercise relate predominantly to extremes of intensity and duration, all older adults should consult with a physician before beginning a new activity program. A prescription for exercise should include both aerobic and resistance training components, and frequent follow-up to improve adherence is highly recommended. (c)2001 CVRR, Inc.

  13. A three-dimensional computerized isometric strength measurement system.

    PubMed

    Black, Nancy L; Das, Biman

    2007-05-01

    The three-dimensional Computerized Isometric Strength Measurement System (CISMS) reliably and accurately measures isometric pull and push strengths in work spaces of paraplegic populations while anticipating comparative studies with other populations. The main elements of the system were: an extendable arm, a vertical supporting track, a rotating platform, a force transducer, stability sensors and a computerized data collection interface. The CISMS with minor modification was successfully used to measure isometric push-up and pull-down strengths of paraplegics and isometric push, pull, push-up and pull-down strength in work spaces for seated and standing able-bodied populations. The instrument has satisfied criteria of versatility, safety and comfort, ease of operation, and durability. Results are accurate within 2N for aligned forces. Costing approximately $1,500 (US) including computer, the system is affordable and accurate for aligned isometric strength measurements.

  14. 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.

  15. Plyometric vs. isometric training influences on tendon properties and muscle output.

    PubMed

    Burgess, Katherine E; Connick, Mark J; Graham-Smith, Philip; Pearson, Stephen J

    2007-08-01

    The purpose of this study was to concurrently determine the effect that plyometric and isometric training has on tendon stiffness (K) and muscle output characteristics to compare any subsequent changes. Thirteen men trained the lower limbs either plyometrically or isometrically 2-3 times a week for a 6-week period. Medial gastrocnemius tendon stiffness was measured in vivo using ultrasonography during ramped isometric contractions before and after training. Mechanical output variables were measured using a force plate during concentric and isometric efforts. Significant (p < 0.05) training-induced increases in tendon K were seen for the plyometric (29.4%; 49.0 +/- 10.8 to 63.4 +/- 9.2 N x mm(-1)) and isometric groups (61.6%; 43.9 +/- 2.5 to 71.0 +/- 7.4 N x mm(-1)). Statistically similar increases in rate of force development and jump height were also seen for both training groups, with increases of 18.9 and 58.6% for the plyometric group and 16.7 and 64.3% for the isometric group, respectively. Jump height was found to be significantly correlated with tendon stiffness, such that stiffness could explain 21% of the variance in jump height. Plyometric training has been shown to place large stresses on the body, which can lead to a potential for injury, whereas explosive isometric training has been shown here to provide similar benefits to that of plyometric training with respect to the measured variables, but with reduced impact forces, and would therefore provide a useful adjunct for athletic training programs within a 6-week time frame.

  16. The effects of acute leucine or leucine-glutamine co-ingestion on recovery from eccentrically biased exercise.

    PubMed

    Waldron, Mark; Ralph, Cameron; Jeffries, Owen; Tallent, Jamie; Theis, Nicola; Patterson, Stephen David

    2018-05-16

    This study investigated the effects of leucine or leucine + glutamine supplementation on recovery from eccentric exercise. In a double-blind independent groups design, 23 men were randomly assigned to a leucine (0.087 g/kg; n = 8), leucine + glutamine (0.087 g/kg + glutamine 0.3 g/kg; n = 8) or placebo (0.3 g/kg maltodextrin; n = 7) group. Participants performed 5 sets of drop jumps, with each set comprising 20 repetitions. Isometric knee-extensor strength, counter-movement jump (CMJ) height, delayed-onset muscle soreness (DOMS) and creatine kinase (CK) were measured at baseline, 1, 24, 48 h and 72 h post-exercise. There was a time × group interaction for isometric strength, CMJ and CK (P < 0.05), with differences between the leucine + glutamine and placebo group at 48 h and 72 h for strength (P = 0.013; d = 1.43 and P < 0.001; d = 2.06), CMJ (P = 0.008; d = 0.87 and P = 0.019; d = 1.17) and CK at 24 h (P = 0.012; d = 0.54) and 48 h (P = 0.010; d = 1.37). The leucine group produced higher strength at 72 h compared to placebo (P = 0.007; d = 1.65) and lower CK at 24 h (P = 0.039; d = 0.63) and 48 h (P = 0.022; d = 1.03). Oral leucine or leucine + glutamine increased the rate of recovery compared to placebo after eccentric exercise. These findings highlight potential benefits of co-ingesting these amino acids to ameliorate recovery.

  17. Time course of the acute effects of core stabilisation exercise on seated postural control.

    PubMed

    Lee, Jordan B; Brown, Stephen H M

    2017-09-20

    Core stabilisation exercises are often promoted for purposes ranging from general fitness to high-performance athletics, and the prevention and rehabilitation of back troubles. These exercises, when performed properly, may have the potential to enhance torso postural awareness and control, yet the potential for achieving immediate gains has not been completely studied. Fourteen healthy young participants performed a single bout of non-fatiguing core stabilisation exercise that consisted of repeated sets of 2 isometric exercises, the side bridge and the four-point contralateral arm-and-leg extension. Seated postural control, using an unstable balance platform on top of a force plate, was assessed before and after exercise, including multiple time points within a 20-minute follow-up period. Nine standard postural control variables were calculated at each time point, including sway displacement and velocity ranges, root mean squares and cumulative path length. Statistical analysis showed that none of the postural control variables were significantly different at any time point following completion of core stabilisation exercise. Thus, we conclude that a single bout of acute core stabilisation exercise is insufficient to immediately improve seated trunk postural control in young healthy individuals.

  18. Electromyographic analysis of upper body, lower body, and abdominal muscles during advanced Swiss ball exercises.

    PubMed

    Marshall, Paul W M; Desai, Imtiaz

    2010-06-01

    Although there is now some evidence examining the use of a Swiss ball during core stability and resistance exercises, this has commonly been performed using basic or isometric exercises. There is currently no evidence examining more advanced Swiss ball exercises. The purpose of this study was to determine whether or not muscle activity measured during advanced Swiss ball exercises was at an approximate intensity recommended for strength or endurance training in advanced, or novice individuals. After a familiarization session, 14 recreationally active subjects performed 6 different "advanced" Swiss ball exercises in a randomized order. The primary dependent variables in this study were the activity levels collected from anterior deltoid, pectoralis major, rectus abdominis (RA), external obliques, lumbar erector spinae, vastus lateralis (VL), and biceps femoris using surface electromyography. All signals were normalized to maximal voluntary isometric contractions performed before testing for each muscle. The results of this study showed that the Swiss ball roll elicited muscle activity in triceps brachii (72.5+/-32.4%) and VL (83.6+/-44.2%) commensurate with the intensity recommended for strength exercises in advanced trainers. Rectus abdominis activity was greatest during the bridge exercise (61.3+/-28.5%, pexercise to elicit RA muscle activity commensurate with a strength training effect. The remainder of the exercises elicited abdominal activity that would require a higher number of repetitions to be performed for an endurance training adaptation. Although this study has provided evidence for one advanced Swiss ball exercise providing a significant whole-body stimulus, the practical difficulty and risks of performing these more complicated Swiss ball exercises may outweigh potential benefits.

  19. Hypertension and physical exercise: The role of oxidative stress.

    PubMed

    Korsager Larsen, Monica; Matchkov, Vladimir V

    2016-01-01

    Oxidative stress is associated with the pathogenesis of hypertension. Decreased bioavailability of nitric oxide (NO) is one of the mechanisms involved in the pathogenesis. It has been suggested that physical exercise could be a potential non-pharmacological strategy in treatment of hypertension because of its beneficial effects on oxidative stress and endothelial function. The aim of this review is to investigate the effect of oxidative stress in relation to hypertension and physical exercise, including the role of NO in the pathogenesis of hypertension. Endothelial dysfunction and decreased NO levels have been found to have the adverse effects in the correlation between oxidative stress and hypertension. Most of the previous studies found that aerobic exercise significantly decreased blood pressure and oxidative stress in hypertensive subjects, but the intense aerobic exercise can also injure endothelial cells. Isometric exercise decreases normally only systolic blood pressure. An alternative exercise, Tai chi significantly decreases blood pressure and oxidative stress in normotensive elderly, but the effect in hypertensive subjects has not yet been studied. Physical exercise and especially aerobic training can be suggested as an effective intervention in the prevention and treatment of hypertension and cardiovascular disease via reduction in oxidative stress. Copyright © 2016 The Lithuanian University of Health Sciences. Production and hosting by Elsevier Urban & Partner Sp. z o.o. All rights reserved.

  20. Reliability and validity of two isometric squat tests.

    PubMed

    Blazevich, Anthony J; Gill, Nicholas; Newton, Robert U

    2002-05-01

    The purpose of the present study was first to examine the reliability of isometric squat (IS) and isometric forward hack squat (IFHS) tests to determine if repeated measures on the same subjects yielded reliable results. The second purpose was to examine the relation between isometric and dynamic measures of strength to assess validity. Fourteen male subjects performed maximal IS and IFHS tests on 2 occasions and 1 repetition maximum (1-RM) free-weight squat and forward hack squat (FHS) tests on 1 occasion. The 2 tests were found to be highly reliable (intraclass correlation coefficient [ICC](IS) = 0.97 and ICC(IFHS) = 1.00). There was a strong relation between average IS and 1-RM squat performance, and between IFHS and 1-RM FHS performance (r(squat) = 0.77, r(FHS) = 0.76; p < 0.01), but a weak relation between squat and FHS test performances (r < 0.55). There was also no difference between observed 1-RM values and those predicted by our regression equations. Errors in predicting 1-RM performance were in the order of 8.5% (standard error of the estimate [SEE] = 13.8 kg) and 7.3% (SEE = 19.4 kg) for IS and IFHS respectively. Correlations between isometric and 1-RM tests were not of sufficient size to indicate high validity of the isometric tests. Together the results suggest that IS and IFHS tests could detect small differences in multijoint isometric strength between subjects, or performance changes over time, and that the scores in the isometric tests are well related to 1-RM performance. However, there was a small error when predicting 1-RM performance from isometric performance, and these tests have not been shown to discriminate between small changes in dynamic strength. The weak relation between squat and FHS test performance can be attributed to differences in the movement patterns of the tests

  1. Acute Effects of the Different Intensity of Static Stretching on Flexibility and Isometric Muscle Force.

    PubMed

    Kataura, Satoshi; Suzuki, Shigeyuki; Matsuo, Shingo; Hatano, Genki; Iwata, Masahiro; Yokoi, Kazuaki; Tsuchida, Wakako; Banno, Yasuhiro; Asai, Yuji

    2017-12-01

    Kataura, S, Suzuki, S, Matsuo, S, Hatano, G, Iwata, M, Yokoi, K, Tsuchida, W, Banno, Y, and Asai, Y. Acute effects of the different intensity of static stretching on flexibility and isometric muscle force. J Strength Cond Res 31(12): 3403-3410, 2017-In various fields, static stretching is commonly performed to improve flexibility, whereas the acute effects of different stretch intensities are unclear. Therefore, we investigated the acute effects of different stretch intensities on flexibility and muscle force. Eighteen healthy participants (9 men and 9 women) performed 180-second static stretches of the right hamstrings at 80, 100, and 120% of maximum tolerable intensity without stretching pain, in random order. The following outcomes were assessed as markers of lower limb function and flexibility: static passive torque (SPT), range of motion (ROM), passive joint (muscle-tendon) stiffness, passive torque (PT) at onset of pain, and isometric muscle force. Static passive torque was significantly decreased after all stretching intensities (p ≤ 0.05). Compared with before stretching at 100 and 120% intensities, ROM and PT were significantly increased after stretching (p ≤ 0.05), and passive stiffness (p = 0.05) and isometric muscle force (p ≤ 0.05) were significantly decreased. In addition, ROM was significantly greater after stretching at 100 and 120% than at 80%, and passive stiffness was significantly lower after 120% than after 80% (p ≤ 0.05). However, all measurements except SPT were unchanged after 80% intensity. There was a weak positive correlation between the intensities of stretching and the relative change for SPT (p ≤ 0.05), a moderate positive correlation with ROM (p ≤ 0.05), and a moderate positive correlation with passive stiffness (p ≤ 0.05). These results indicate that static stretching at greater intensity is more effective for increasing ROM and decreasing passive muscle-tendon stiffness.

  2. Exercise Training for Blood Pressure: A Systematic Review and Meta‐analysis

    PubMed Central

    Cornelissen, Veronique A.; Smart, Neil A.

    2013-01-01

    Background We conducted meta‐analyses examining the effects of endurance, dynamic resistance, combined endurance and resistance training, and isometric resistance training on resting blood pressure (BP) in adults. The aims were to quantify and compare BP changes for each training modality and identify patient subgroups exhibiting the largest BP changes. Methods and Results Randomized controlled trials lasting ≥4 weeks investigating the effects of exercise on BP in healthy adults (age ≥18 years) and published in a peer‐reviewed journal up to February 2012 were included. Random effects models were used for analyses, with data reported as weighted means and 95% confidence interval. We included 93 trials, involving 105 endurance, 29 dynamic resistance, 14 combined, and 5 isometric resistance groups, totaling 5223 participants (3401 exercise and 1822 control). Systolic BP (SBP) was reduced after endurance (−3.5 mm Hg [confidence limits −4.6 to −2.3]), dynamic resistance (−1.8 mm Hg [−3.7 to −0.011]), and isometric resistance (−10.9 mm Hg [−14.5 to −7.4]) but not after combined training. Reductions in diastolic BP (DBP) were observed after endurance (−2.5 mm Hg [−3.2 to −1.7]), dynamic resistance (−3.2 mm Hg [−4.5 to −2.0]), isometric resistance (−6.2 mm Hg [−10.3 to −2.0]), and combined (−2.2 mm Hg [−3.9 to −0.48]) training. BP reductions after endurance training were greater (P<0.0001) in 26 study groups of hypertensive subjects (−8.3 [−10.7 to −6.0]/−5.2 [−6.8 to −3.4] mm Hg) than in 50 groups of prehypertensive subjects (−2.1 [−3.3 to −0.83]/−1.7 [−2.7 to −0.68]) and 29 groups of subjects with normal BP levels (−0.75 [−2.2 to +0.69]/−1.1 [−2.2 to −0.068]). BP reductions after dynamic resistance training were largest for prehypertensive participants (−4.0 [−7.4 to −0.5]/−3.8 [−5.7 to −1.9] mm Hg) compared with patients with hypertension or normal BP. Conclusion Endurance

  3. Muscle damage and repeated bout effect induced by enhanced eccentric squats.

    PubMed

    Coratella, Giuseppe; Chemello, Alessandro; Schena, Federico

    2016-12-01

    Muscle damage and repeated bout effect have been studied after pure eccentric-only exercise. The aim of this study was to evaluate muscle damage and repeated bout effect induced by enhanced eccentric squat exercise using flywheel device. Thirteen healthy males volunteered for this study. Creatine kinase blood activity (CK), quadriceps isometric peak torque and muscle soreness were used as markers of muscle damage. The dependent parameters were measured at baseline, immediately after and each day up to 96 hours after the exercise session. The intervention consisted of 100 repetitions of enhanced eccentric squat exercise using flywheel device. The same protocol was repeated after 4 weeks. After the first bout, CK and muscle soreness were significantly greater (P<0.05) than baseline respectively up to 72 and 96 hours. Isometric peak torque was significantly lower (P<0.05) up to 72 hours. After the second bout, CK showed no significant increase (P>0.05), while isometric peak torque and muscle soreness returned to values similar to baseline after respectively 48 and 72 hours. All muscle damage markers were significantly lower after second compared to first bout. The enhanced eccentric exercise induced symptoms of muscle damage up to 96 hours. However, it provided muscle protection after the second bout, performed four weeks later. Although it was not eccentric-only exercise, the enhancement of eccentric phase provided muscle protection.

  4. Influence of Body Position on Shoulder and Trunk Muscle Activation During Resisted Isometric Shoulder External Rotation.

    PubMed

    Krause, David A; Dueffert, Lucas G; Postma, Jaclyn L; Vogler, Eric T; Walsh, Amy J; Hollman, John H

    External rotation (ER) strengthening of the shoulder is an integral component of rehabilitative and preventative programs for overhead athletes. A variety of shoulder ER strengthening exercises are reported, including those intended to integrate the core musculature. The purpose of this study was to examine ER torque and electromyographic (EMG) activation of shoulder and trunk muscles while performing resisted isometric shoulder ER in 3 positions (standing, side lying, and side plank). Significantly greater force and shoulder muscle activation would be generated while side lying given the inherent stability of the position, and greater trunk muscle activation would be generated in the less stable plank position. Quasi-experimental repeated-measures study. Level 5. A convenience sample of 25 healthy overhead recreational athletes (9 men, 16 women) participated in this study. EMG electrodes were placed on the infraspinatus, posterior deltoid, middle trapezius, multifidi, internal obliques, and external obliques. EMG signals were normalized to a maximal isometric contraction. Participants performed resisted isometric ER in standing, side-lying, and side plank positions. Results were analyzed using a repeated-measures analysis of variance with post hoc Bonferroni corrections (α = 0.05). There was no significant difference in ER torque between positions (α = 0.05). A significant difference in EMG activity of shoulder and trunk musculature between positions was found in 7 of the 8 muscles monitored. Significantly greater EMG activity in the infraspinatus, middle trapezius, and the nondominant external and internal obliques was found in the side plank position as compared with standing and side lying. While there was no difference in ER torque between the 3 exercise positions, EMG activity of the shoulder and trunk muscles was dependent on body position. If a clinician is seeking to integrate trunk muscle activation while performing shoulder ER strengthening, the side

  5. Does an exercise aimed at improving swallow function have an effect on vocal function in the healthy elderly?

    PubMed

    Easterling, Caryn

    2008-09-01

    Age-related sarcopenia or muscle wasting contributes to changes in the ability to perform activities of daily living, changes in deglutition, and changes in vocal function. The Shaker Exercise, an isometric and isokinetic exercise, has been shown to strengthen suprahyoid muscles and increase deglutitive anteroposterior (AP) upper esophageal sphincter (UES) opening diameter. The aim of this study was to determine if this exercise has an effect on the age-related changes in vocal function and deglutition in healthy older adults. Eleven females and 10 males, aged 65-78 years (mean = 70 +/- 4 years) and with a negative history for dysphagia and voice disorders, participated by exercising three times per day for 6 weeks. Five age-matched controls did not perform the exercise. Acoustic analysis of voice and biomechanical analysis of deglutition were performed before and after 6 weeks of exercise. Controls participated in voice analysis only. Dysphonia Severity Index (DSI), a multivariate voice index, was used to compare voice production initially and after 6 weeks. Deglutitive biomechanical measures increased and DSI scores improved in 10 of 21 participants following 6 weeks of the exercise. DSI for controls did not change over the 6-week period. Ten of 21 exercise participants experienced improved deglutitive biomechanics and DSI scores. Accuracy of exercise performance, compliance, and/or disclosed alterations in health status may contribute to the lack of deglutitive and DSI change in the participants who did not experience change in function. A large randomized control study, including periodic monitoring of health status, exercise performance accuracy, and compliance, is warranted to evaluate the affect of this exercise on deglutition as well as voice. The Shaker Exercise could be recommended as a preventative measure to diminish the effect of sarcopenia on the muscles used in deglutition and voice and alter the progression of the characteristic senescent voice and

  6. Do Differences in Levels, Types, and Duration of Muscle Contraction Have an Effect on the Degree of Post-exercise Depression?

    PubMed

    Miyaguchi, Shota; Kojima, Sho; Kirimoto, Hikari; Tamaki, Hiroyuki; Onishi, Hideaki

    2016-01-01

    We conducted two experiments to determine how differences in muscle contraction levels, muscle contraction types, and movement duration affect degree of post-exercise depression (PED) after non-exhaustive, repetitive finger movement. Twelve healthy participants performed repetitive abduction movements of the right index finger at 2 Hz. In experiment 1, we examined the effects of muscle contraction levels at 10, 20, and 30% maximum voluntary contraction and the effects of muscle contraction types at isotonic and isometric contraction. In experiment 2, we examined the effects of movement duration at 2 and 6 min. Motor-evoked potentials (MEPs) were recorded from the right first dorsal interosseous muscle before movement tasks and 1-10 min after movement tasks. MEP amplitudes after isotonic contraction tasks were significantly smaller than those after isometric contraction tasks and decreased with increasing contraction levels, but were independent of movement duration. This study demonstrated that the degree of PED after non-exhaustive repetitive finger movement depended on muscle contraction levels and types. Thus, the degree of PED may depend on the levels of activity in the motor cortex during a movement task. This knowledge will aid in the design of rehabilitation protocols.

  7. Model-based analysis of fatigued human knee extensors : Effects of isometrically induced fatigue on Hill-type model parameters and ballistic contractions.

    PubMed

    Penasso, Harald; Thaller, Sigrid

    2018-05-05

    This study investigated the effect of isometrically induced fatigue on Hill-type muscle model parameters and related task-dependent effects. Parameter identification methods were used to extract fatigue-related parameter trends from isometric and ballistic dynamic maximum voluntary knee extensions. Nine subjects, who completed ten fatiguing sets, each consisting of nine 3 s isometric maximum voluntary contractions with 3 s rest plus two ballistic contractions with different loads, were analyzed. Only at the isometric task, the identified optimized model parameter values of muscle activation rate and maximum force generating capacity of the contractile element decreased from [Formula: see text] to [Formula: see text] Hz and from [Formula: see text] to [Formula: see text] N, respectively. For all tasks, the maximum efficiency of the contractile element, mathematically related to the curvature of the force-velocity relation, increased from [Formula: see text] to [Formula: see text]. The model parameter maximum contraction velocity decreased from [Formula: see text] to [Formula: see text] m/s and the stiffness of the serial elastic element from [Formula: see text] to [Formula: see text] N/mm. Thus, models of fatigue should consider fatigue dependencies in active as well as in passive elements, and muscle activation dynamics should account for the task dependency of fatigue.

  8. Effect of Upper-Extremity Strengthening Exercises on the Lumbar Strength, Disability and Pain of Patients with Chronic Low Back Pain: A Randomized Controlled Study.

    PubMed

    Atalay, Erdem; Akova, Bedrettin; Gür, Hakan; Sekir, Ufuk

    2017-12-01

    The present study aimed to analyze the impacts of a low back rehabilitation program accompanied with neck, shoulder and upper back exercises on pain, disability, and physical characteristics of patients with chronic low back pain. Twenty sedentary male patients with chronic low back pain participated in the study on a voluntary basis. The patients were randomly allocated into two groups: a conventional low back exercise group (CE) and a supported exercise group (SE; CE plus upper back, neck, and shoulder exercises). The Modified Oswestry Disability Questionnaire (MODQ) was used to evaluate the disability status and the Visual Analog Scale (VAS) was used to identify the pain states of the patients. In addition, neck, lumbar and shoulder isokinetic and isometric strengths of the patients were evaluated. The CE group performed lumbar stretching, mobilization and stabilization exercises in addition to low-back and abdominal isometric and concentric strengthening exercises. The SE group performed static stretching and isotonic exercises for the neck, upper-back, and shoulder muscles, in addition to the exercises performed in CE group. The exercises were implemented 3 days a week for 6 weeks in both groups. Following the 6-week exercise periods in both groups, statistically significant (p < 0.01) improvements were observed in the patients' levels of pain and the scores of MODQ reflecting an easing of disability. With respect to the levels of pain and disability, the improvements observed in the SE group was significantly (p < 0.01) greater than the improvement observed in the CE group. Based on the findings of this study, we can conclude that a low back exercise program used in combination with neck, shoulder and upper back exercises reduces the level of pain and disability in patients with chronic low back pain more prominently than conventional low back exercises.

  9. The influence of isometric preload on power expressed during bench press in strength-trained men.

    PubMed

    Bartolomei, Sandro; Fukuda, David H; Hoffman, Jay R; Stout, Jeffrey R; Merni, Franco

    2017-03-01

    The purpose of this study was to compare the power expressed during the bench press exercise in resistance-trained men following different pre-activation conditions. Twenty-two trained men (age 24.1 ± 1.7 years, height 178.6 ± 6.1 cm, body mass 81.1 ± 10.6 kg) completed a maximal effort bench press (1-RM) test (100.0 kg ± 8.1 kg). In a subsequent assessment, each participant performed concentric bench press movements with loads of 20%, 30%, 40% and 50% of their 1-RM preceded by either a concentric contraction (CC), a low isometric preload (LIP; 70% 1-RM) or a high isometric preload (HIP; 100% 1-RM) conditions. All movements were performed in a Smith machine with a settable quick-release device. Participants performed all three conditions in randomized fashion. Results indicated that power outputs during the bench press exercise following HIP were significantly (p < 0.05) greater than CC at 20% 1-RM (+9%), 30% 1-RM (+16%) and 40% 1-RM (+14%), and LIP at 20% 1-RM (+4%), 30% 1-RM (+20%) and 40% 1-RM (+15%). No differences were found between conditions at 50% 1-RM. Area under the force-power curve with HIP was greater (p < 0.05) than with CC and LIP. In conclusion, results of this study indicate that the use of a HIP (100% 1-RM) in trained participants results in significantly greater power output during the concentric phase of a multi-joint exercise when compared to standard concentric movement.

  10. Microprocessor Controlled Isometric Contractions of Cat Gastrocnemius Muscle.

    DTIC Science & Technology

    1981-12-01

    A-A15 504 AIR FORCE INST OF TECH WRIGHT-PATTERSON AFS OH 5CHOO--ETC F/6 6/2 MICROPROCESSOR CONTROLLED ISOMETRIC CONTRACTIONS OF CAT GASTROC-ETC(U) D...CONTROLLED ISOMETRIC CONTRACTIONS OF CAT GASTROCNEMIUS MUSCLE THESIS Presented to the Faculty of the School of Engineering of the Air Force Institute of...1981 Appzoved for public release; distribution unlimited. AFIT/GE/EE/81D-4O \\ MICROPROCESSOR CONTROLLED ISOMETRIC COMUtCTIONS OF CAT GASTfOCNEMIUS i

  11. The Effects of Montmorency Tart Cherry Concentrate Supplementation on Recovery Following Prolonged, Intermittent Exercise.

    PubMed

    Bell, Phillip G; Stevenson, Emma; Davison, Gareth W; Howatson, Glyn

    2016-07-22

    This study investigated Montmorency tart cherry concentrate (MC) supplementation on markers of recovery following prolonged, intermittent sprint activity. Sixteen semi-professional, male soccer players, who had dietary restrictions imposed for the duration of the study, were divided into two equal groups and consumed either MC or placebo (PLA) supplementation for eight consecutive days (30 mL twice per day). On day 5, participants completed an adapted version of the Loughborough Intermittent Shuttle Test (LISTADAPT). Maximal voluntary isometric contraction (MVIC), 20 m Sprint, counter movement jump (CMJ), agility and muscle soreness (DOMS) were assessed at baseline, and 24, 48 and 72 h post-exercise. Measures of inflammation (IL-1-β, IL-6, IL-8, TNF-α, hsCRP), muscle damage (CK) and oxidative stress (LOOH) were analysed at baseline and 1, 3, 5, 24, 48 and 72 h post-exercise. Performance indices (MVIC, CMJ and agility) recovered faster and muscle soreness (DOMS) ratings were lower in the MC group (p < 0.05). Additionally, the acute inflammatory response (IL-6) was attenuated in the MC group. There were no effects for LOOH and CK. These findings suggest MC is efficacious in accelerating recovery following prolonged, repeat sprint activity, such as soccer and rugby, and lends further evidence that polyphenol-rich foods like MC are effective in accelerating recovery following various types of strenuous exercise.

  12. Effects of Jaw Clenching and Jaw Alignment Mouthpiece Use on Force Production During Vertical Jump and Isometric Clean Pull.

    PubMed

    Allen, Charles R; Fu, Yang-Chieh; Cazas-Moreno, Vanessa; Valliant, Melinda W; Gdovin, Jacob R; Williams, Charles C; Garner, John C

    2018-01-01

    Allen, CR, Fu, Y-C, Cazas-Moreno, V, Valliant, MW, Gdovin, JR, Williams, CC, and Garner, JC. Effects of jaw clenching and jaw alignment mouthpiece use on force production during vertical jump and isometric clean pull. J Strength Cond Res 32(1): 237-243, 2018-This study examined the effects of jaw clenching, a self-adapted, jaw-repositioning mouthpiece on force production during maximum countermovement vertical jump and maximum isometric midthigh clean pull assessments in an attempt to determine any ergogenic effect attributable to clenching, jaw-repositioning mouthpiece use, or the combination of both. Thirty-six male subjects performed vertical jump and isometric clean pull assessments from a force platform under various mouthpiece and clench conditions. A 3 × 2 (mouthpiece × clench) repeated-measures analysis of variance was conducted to analyze each of the following force production variables for both assessments: peak force, normalized peak force, and rate of force development. In addition, jump height was analyzed for the vertical jump. Results revealed improvements in peak force (F1,35 = 15.84, p ≤ 0.001, (Equation is included in full-text article.)= 0.31), normalized peak force (F1,35 = 16.28, p ≤ 0.001, (Equation is included in full-text article.)= 0.32), and rate of force development (F1,35 = 12.89, p = 0.001, (Equation is included in full-text article.)= 0.27) during the isometric clean pull assessment when participants maximally clenched their jaw, regardless of mouthpiece condition. There were no statistically significant differences in jump height, peak force, normalized peak force, or rate of force development during the vertical jump for any treatment condition. This study supports previous research demonstrating that the implementation of remote voluntary contractions such as jaw clenching can lead to concurrent activation potentiation and a resulting ergogenic effect during activities involving and requiring high-force production.

  13. The effects of a repeated bout of eccentric exercise on indices of muscle damage and delayed onset muscle soreness.

    PubMed

    Paddon-Jones, D; Muthalib, M; Jenkins, D

    2000-03-01

    This study examined markers of muscle damage following a repeated bout of maximal isokinetic eccentric exercise performed prior to full recovery from a previous bout. Twenty non-resistance trained volunteers were randomly assigned to a control (CON, n=10) or experimental (EXP, n=10) group. Both groups performed 36 maximal isokinetic eccentric contractions of the elbow flexors of the non-dominant arm (ECC1). The EXP group repeated the same eccentric exercise bout two days later (ECC2). Total work and peak eccentric torque were recorded during each set of ECC1 and ECC2. Isometric torque, delayed onset muscle soreness (DOMS), flexed elbow angle and plasma creatine kinase (CK) activity were measured prior to and immediately following ECC1 and ECC2. at 24h intervals for 7 days following ECC1 and finally on day 11. In both groups, all dependent variables changed significantly during the 2 days following ECC1. A further acute post-exercise impairment in isometric torque (30 +/- 5%) and flexed elbow angle (20 +/- 4%) was observed following ECC2 (p<0.05), despite EXP subjects producing uniformly lower work and peak eccentric torque values during ECC2 (p<0.05). No other significant differences between the CON and EXP groups were observed throughout the study (p>0.05). These findings suggest that when maximal isokinetic eccentric exercise is repeated two days after experiencing of contraction-induced muscle damage, the recovery time course is not significantly altered.

  14. Transcranial direct current stimulation improves isometric time to exhaustion of the knee extensors.

    PubMed

    Angius, L; Pageaux, B; Hopker, J; Marcora, S M; Mauger, A R

    2016-12-17

    Transcranial direct current stimulation (tDCS) can increase cortical excitability of a targeted brain area, which may affect endurance exercise performance. However, optimal electrode placement for tDCS remains unclear. We tested the effect of two different tDCS electrode montages for improving exercise performance. Nine subjects underwent a control (CON), placebo (SHAM) and two different tDCS montage sessions in a randomized design. In one tDCS session, the anodal electrode was placed over the left motor cortex and the cathodal on contralateral forehead (HEAD), while for the other montage the anodal electrode was placed over the left motor cortex and cathodal electrode above the shoulder (SHOULDER). tDCS was delivered for 10min at 2.0mA, after which participants performed an isometric time to exhaustion (TTE) test of the right knee extensors. Peripheral and central neuromuscular parameters were assessed at baseline, after tDCS application and after TTE. Heart rate (HR), ratings of perceived exertion (RPE), and leg muscle exercise-induced muscle pain (PAIN) were monitored during the TTE. TTE was longer and RPE lower in the SHOULDER condition (P<0.05). Central and peripheral parameters, and HR and PAIN did not present any differences between conditions after tDCS stimulation (P>0.05). In all conditions maximal voluntary contraction (MVC) significantly decreased after the TTE (P<0.05) while motor-evoked potential area (MEP) increased after TTE (P<0.05). These findings demonstrate that SHOULDER montage is more effective than HEAD montage to improve endurance performance, likely through avoiding the negative effects of the cathode on excitability. Copyright © 2016 The Author(s). Published by Elsevier Ltd.. All rights reserved.

  15. Effects of acute exercise on attenuated vagal baroreflex function during bed rest

    NASA Technical Reports Server (NTRS)

    Convertino, Victor A.; Doerr, Donald F.; Guell, Antonio; Marini, J.-F.

    1992-01-01

    We measured carotid baroreceptor-cardiac reflex responses in six healthy men, 24 h before and 24 h after a bout of leg exercise during 6 deg head-down bed rest to determine if depressed vagal baroreflex function associated with exposure to microgravity environments could be reversed by a single exposure to acute intense exercise. Baroreflex responses were measured before bed rest and on day 7 of bed rest. An exercise bout consisting of dynamic and isometric actions of the quadriceps at graded speeds and resistances was performed on day 8 of bed rest and measurements of baroreflex response were repeated 24 h later. Vagally-mediated cardiac responses were provoked with ramped neck pressure-suction sequences comprising pressure elevations to +40 mm Hg, followed by serial, R-wave triggered 15 mm Hg reductions, to -65 mm Hg. Baroreceptor stimulus-cardiac response relationships were derived by plotting each R-R interval as a function of systolic pressure less the neck chamber pressure applied during the interval. Compared with pre-bed rest baseline measurements, 7 d of bed rest decreased the gain (maximum slope) of the baroreflex stimulus-response relationship by 16.8 +/- 3.4 percent (p less than 0.05). On day 9 of bed rest, 24 h after exercise, the maximum slope of the baroreflex stimulus-response relationship was increased (p less than 0.05) by 10.7 +/- 3.7 percent above pre-bed rest levels and 34.3 +/- 7.9 percent above bed rest day 7. Our data verify that vagally-mediated baroreflex function is depressed by exposure to simulated microgravity and demonstrate that this effect can be acutely reversed by exposure to a single bout of intense exercise.

  16. Postactivation potentiation biases maximal isometric strength assessment.

    PubMed

    Lima, Leonardo Coelho Rabello; Oliveira, Felipe Bruno Dias; Oliveira, Thiago Pires; Assumpção, Claudio de Oliveira; Greco, Camila Coelho; Cardozo, Adalgiso Croscato; Denadai, Benedito Sérgio

    2014-01-01

    Postactivation potentiation (PAP) is known to enhance force production. Maximal isometric strength assessment protocols usually consist of two or more maximal voluntary isometric contractions (MVCs). The objective of this study was to determine if PAP would influence isometric strength assessment. Healthy male volunteers (n = 23) performed two five-second MVCs separated by a 180-seconds interval. Changes in isometric peak torque (IPT), time to achieve it (tPTI), contractile impulse (CI), root mean square of the electromyographic signal during PTI (RMS), and rate of torque development (RTD), in different intervals, were measured. Significant increases in IPT (240.6 ± 55.7 N·m versus 248.9 ± 55.1 N·m), RTD (746 ± 152 N·m·s(-1) versus 727 ± 158 N·m·s(-1)), and RMS (59.1 ± 12.2% RMSMAX  versus 54.8 ± 9.4% RMSMAX) were found on the second MVC. tPTI decreased significantly on the second MVC (2373 ± 1200 ms versus 2784 ± 1226 ms). We conclude that a first MVC leads to PAP that elicits significant enhancements in strength-related variables of a second MVC performed 180 seconds later. If disconsidered, this phenomenon might bias maximal isometric strength assessment, overestimating some of these variables.

  17. The effects of elevated pain inhibition on endurance exercise performance.

    PubMed

    Flood, Andrew; Waddington, Gordon; Keegan, Richard J; Thompson, Kevin G; Cathcart, Stuart

    2017-01-01

    The ergogenic effects of analgesic substances suggest that pain perception is an important regulator of work-rate during fatiguing exercise. Recent research has shown that endogenous inhibitory responses, which act to attenuate nociceptive input and reduce perceived pain, can be increased following transcranial direct current stimulation of the hand motor cortex. Using high-definition transcranial direct current stimulation (HD-tDCS; 2 mA, 20 min), the current study aimed to examine the effects of elevated pain inhibitory capacity on endurance exercise performance. It was hypothesised that HD-tDCS would enhance the efficiency of the endogenous pain inhibitory response and improve endurance exercise performance. Twelve healthy males between 18 and 40 years of age ( M  = 24.42 ± 3.85) were recruited for participation. Endogenous pain inhibitory capacity and exercise performance were assessed before and after both active and sham (placebo) stimulation. The conditioned pain modulation protocol was used for the measurement of pain inhibition. Exercise performance assessment consisted of both maximal voluntary contraction (MVC) and submaximal muscular endurance performance trials using isometric contractions of the non-dominant leg extensors. Active HD-tDCS (pre-tDCS, -.32 ± 1.33 kg; post-tDCS, -1.23 ± 1.21 kg) significantly increased pain inhibitory responses relative to the effects of sham HD-tDCS (pre-tDCS, -.91 ± .92 kg; post-tDCS, -.26 ± .92 kg; p  = .046). Irrespective of condition, peak MVC force and muscular endurance was reduced from pre- to post-stimulation. HD-tDCS did not significantly influence this reduction in maximal force (active: pre-tDCS, 264.89 ± 66.87 Nm; post-tDCS, 236.33 ± 66.51 Nm; sham: pre-tDCS, 249.25 ± 88.56 Nm; post-tDCS, 239.63 ± 67.53 Nm) or muscular endurance (active: pre-tDCS, 104.65 ± 42.36 s; post-tDCS, 93.07 ± 33.73 s; sham: pre-tDCS, 123.42 ± 72.48 s; post-tDCS, 100.27 ± 44.25 s). Despite increasing pain

  18. Probiotic Streptococcus thermophilus FP4 and Bifidobacterium breve BR03 Supplementation Attenuates Performance and Range-of-Motion Decrements Following Muscle Damaging Exercise.

    PubMed

    Jäger, Ralf; Purpura, Martin; Stone, Jason D; Turner, Stephanie M; Anzalone, Anthony J; Eimerbrink, Micah J; Pane, Marco; Amoruso, Angela; Rowlands, David S; Oliver, Jonathan M

    2016-10-14

    Probiotics have immunomodulatory effects. However, little is known about the potential benefit of probiotics on the inflammation subsequent to strenuous exercise. In a double-blind, randomized, placebo controlled, crossover design separated by a 21-day washout, 15 healthy resistance-trained men ingested an encapsulated probiotic Streptococcus ( S. ) thermophilus FP4 and Bifidobacterium ( B. ) breve BR03 at 5 bn live cells (AFU) concentration each, or a placebo, daily for 3 weeks prior to muscle-damaging exercise (ClinicalTrials.gov NCT02520583). Isometric strength, muscle soreness, range of motion and girth, and blood interleukin-6 (IL-6) and creatine kinase (CK) concentrations were measured from pre- to 72 h post-exercise. Statistical analysis was via mixed models and magnitude-based inference to the standardized difference. Probiotic supplementation resulted in an overall decrease in circulating IL-6, which was sustained to 48 h post-exercise. In addition, probiotic supplementation likely enhanced isometric average peak torque production at 24 to 72 h into the recovery period following exercise (probiotic-placebo point effect ±90% CI: 24 h, 11% ± 7%; 48 h, 12% ± 18%; 72 h, 8% ± 8%). Probiotics also likely moderately increased resting arm angle at 24 h (2.4% ± 2.0%) and 48 h (1.9% ± 1.9%) following exercise, but effects on soreness and flexed arm angle and CK were unclear. These data suggest that dietary supplementation with probiotic strains S. thermophilus FP4 and B. breve BR03 attenuates performance decrements and muscle tension in the days following muscle-damaging exercise.

  19. The efficacy of unsupervised home-based exercise regimens in comparison to supervised laboratory-based exercise training upon cardio-respiratory health facets.

    PubMed

    Blackwell, James; Atherton, Philip J; Smith, Kenneth; Doleman, Brett; Williams, John P; Lund, Jonathan N; Phillips, Bethan E

    2017-09-01

    Supervised high-intensity interval training (HIIT) can rapidly improve cardiorespiratory fitness (CRF). However, the effectiveness of time-efficient unsupervised home-based interventions is unknown. Eighteen volunteers completed either: laboratory-HIIT (L-HIIT); home-HIIT (H-HIIT) or home-isometric hand-grip training (H-IHGT). CRF improved significantly in L-HIIT and H-HIIT groups, with blood pressure improvements in the H-IHGT group only. H-HIIT offers a practical, time-efficient exercise mode to improve CRF, away from the laboratory environment. H-IHGT potentially provides a viable alternative to modify blood pressure in those unable to participate in whole-body exercise. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

  20. Creatine Loading, Resistance Exercise Performance, and Muscle Mechanics.

    ERIC Educational Resources Information Center

    Stevenson, Scott W.; Dudley, Gary A.

    2001-01-01

    Examined whether creatine (CR) monohydrate loading would alter resistance exercise performance, isometric strength, or in vivo contractile properties of the quadriceps femoris muscle compared with placebo loading in resistance-trained athletes. Overall, CR loading did not provide an ergogenic benefit for the unilateral dynamic knee extension…

  1. Exercisers' identities and exercise dependence: the mediating effect of exercise commitment.

    PubMed

    Lu, Frank Jing-Horng; Hsu, Eva Ya-Wen; Wang, Junn-Ming; Huang, Mei-Yao; Chang, Jo-Ning; Wang, Chien-Hsin

    2012-10-01

    The purpose of this study was to examine the associations of exercise identity, exercise commitment, exercise dependence, and, particularly, the mediating effects of exercise commitment on the relationship between exercise identity and exercise dependence. 253 Taiwanese regular exercisers completed measures, including the Exercise Dependence Scale-Revised, the Exercise Identity Scale, the Exercise Commitment Scale, and the Godin Leisure Time Exercise Questionnaire. Results showed that exercise identity, exercise dependence, and two types of exercise commitment were moderately to highly correlated. Furthermore, structural equation modelling indicated that a "have to" commitment partially mediated the relationship between exercise identity and exercise dependence. Based on the mediating role of a "have to" commitment, the findings are particularly informative to exercise instructors and for exercise program managers.

  2. Isometric arm counter-pressure maneuvers to abort impending vasovagal syncope.

    PubMed

    Brignole, Michele; Croci, Francesco; Menozzi, Carlo; Solano, Alberto; Donateo, Paolo; Oddone, Daniele; Puggioni, Enrico; Lolli, Gino

    2002-12-04

    We hypothesized that isometric arm exercises were able to increase blood pressure (BP) during the phase of impending vasovagal syncope and allow the patient to avoid losing consciousness. Hypotension is always present during the prodromal phase of vasovagal syncope. We evaluated the effect of handgrip (HG) and arm-tensing in 19 patients affected by tilt-induced vasovagal syncope. The study consisted of an acute single-blind, placebo-controlled, randomized, cross-over tilt-table efficacy study and a clinical follow-up feasibility study. In the acute tilt study, HG was administered for 2 min, starting at the time of onset of symptoms of impending syncope. In the active arm, HG caused an increase in systolic blood pressure (SBP) from 92 +/- 10 mm Hg to 105 +/- 38 mm Hg, whereas in the placebo arm SBP decreased from 91 +/- 11 mm Hg to 73 +/- 21 mm Hg (p = 0.008). Heart rate behavior was similar in the two arms. In the active arm, 63% of patients became asymptomatic, versus 11% in the control arm (p = 0.02); conversely, only 5% of patients developed syncope, versus 47% in the control arm (p = 0.01). The patients were trained to self-administer arm-tensing treatment as soon as symptoms of impending syncope occurred. During 9 +/- 3 months of follow-up, the treatment was actually performed in 95/97 episodes of impending syncope (98%) and was successful in 94/95 (99%). No patients suffered injury or other adverse morbidity related to the relapses. Isometric arm contraction is able to abort impending vasovagal syncope by increasing systemic BP. Arm counter-pressure maneuvers can be proposed as a new, feasible, safe, and well accepted first-line treatment for vasovagal syncope.

  3. Effect of an ADP analog on isometric force and ATPase activity of active muscle fibers.

    PubMed

    Karatzaferi, Christina; Myburgh, Kathryn H; Chinn, Marc K; Franks-Skiba, Kathleen; Cooke, Roger

    2003-04-01

    The role played by ADP in modulating cross-bridge function has been difficult to study, because it is hard to buffer ADP concentration in skinned muscle preparations. To solve this, we used an analog of ADP, spin-labeled ADP (SL-ADP). SL-ADP binds tightly to myosin but is a very poor substrate for creatine kinase or pyruvate kinase. Thus ATP can be regenerated, allowing well-defined concentrations of both ATP and SL-ADP. We measured isometric ATPase rate and isometric tension as a function of both [SL-ADP], 0.1-2 mM, and [ATP], 0.05-0.5 mM, in skinned rabbit psoas muscle, simulating fresh or fatigued states. Saturating levels of SL-ADP increased isometric tension (by P'), the absolute value of P' being nearly constant, approximately 0.04 N/mm(2), in variable ATP levels, pH 7. Tension decreased (50-60%) at pH 6, but upon addition of SL-ADP, P' was still approximately 0.04 N/mm(2). The ATPase was inhibited competitively by SL-ADP with an inhibition constant, K(i), of approximately 240 and 280 microM at pH 7 and 6, respectively. Isometric force and ATPase activity could both be fit by a simple model of cross-bridge kinetics.

  4. Does combined strength training and local vibration improve isometric maximum force? A pilot study.

    PubMed

    Goebel, Ruben; Haddad, Monoem; Kleinöder, Heinz; Yue, Zengyuan; Heinen, Thomas; Mester, Joachim

    2017-01-01

    The aim of the study was to determine whether a combination of strength training (ST) and local vibration (LV) improved the isometric maximum force of arm flexor muscles. ST was applied to the left arm of the subjects; LV was applied to the right arm of the same subjects. The main aim was to examine the effect of LV during a dumbbell biceps curl (Scott Curl) on isometric maximum force of the opposite muscle among the same subjects. It is hypothesized, that the intervention with LV produces a greater gain in isometric force of the arm flexors than ST. Twenty-seven collegiate students participated in the study. The training load was 70% of the individual 1 RM. Four sets with 12 repetitions were performed three times per week during four weeks. The right arm of all subjects represented the vibration trained body side (VS) and the left arm served as the traditional trained body side (TTS). A significant increase of isometric maximum force in both body sides (Arms) occurred. VS, however, significantly increased isometric maximum force about 43% in contrast to 22% of the TTS. The combined intervention of ST and LC improves isometric maximum force of arm flexor muscles. III.

  5. Effects of fatiguing constant versus alternating intensity intermittent isometric muscle actions on maximal torque and neuromuscular responses

    PubMed Central

    Smith, C.M.; Housh, T.J.; Hill, E.C.; Cochrane, K.C.; Jenkins, N.D.M.; Schmidt, R.J.; Johnson, G.O.

    2016-01-01

    Objective: To determine the effects of constant versus alternating applications of torque during fatiguing, intermittent isometric muscle actions of the leg extensors on maximal voluntary isometric contraction (MVIC) torque and neuromuscular responses. Methods: Sixteen subjects performed two protocols, each consisting of 50 intermittent isometric muscle actions of the leg extensors with equal average load at a constant 60% MVIC or alternating 40 then 80% (40/80%) MVIC with a work-to-rest ratio of 6-s on and 2-s off. MVIC torque as well as electromyographic signals from the vastus lateralis (VL), vastus medialis (VM), and rectus femoris (RF) and mechanomyographic signals from the VL were recorded pretest, immediately posttest, and 5-min posttest. Results: The results indicated that there were no time-related differences between the 60% MVIC and 40/80% MVIC protocols. The MVIC torque decreased posttest (22 to 26%) and remained depressed 5-min posttest (9%). There were decreases in electromyographic frequency (14 to 19%) and mechanomyographic frequency (23 to 24%) posttest that returned to pretest levels 5-min posttest. There were no changes in electromyographic amplitude and mechanomyogrpahic amplitude. Conclusions: These findings suggested that these neuromuscular parameters did not track the fatigue-induced changes in MVIC torque after 5-min of recovery. PMID:27973384

  6. Peripheral Vascular Resistance Impairment during Isometric Physical Exercise in Normotensive Offspring of Hypertensive Parents.

    PubMed

    Portela, Natália; Amaral, Josária Ferraz; Mira, Pedro Augusto de Carvalho; Souza, Livia Victorino de; Martinez, Daniel Godoy; Laterza, Mateus Camaroti

    2017-07-10

    A family history of hypertension is associated with vascular and autonomic abnormalities, as well as an impaired neurohemodynamic response to exercise. To test the hypothesis that normotensive individuals with a family history of hypertension present an impaired peripheral vascular resistance response to exercise. The study included 37 normotensive volunteers of both sexes who were sedentary, eutrophic, and nonsmokers, comprising 23 with (FH+; 24 ± 3 years) and 14 without (FH-; 27 ± 5 years) a family history of hypertension. Blood pressure, heart rate (DIXTAL®), forearm blood flow (Hokanson®), and peripheral vascular resistance were simultaneously measured for 3 minutes during rest and, subsequently, for 3 minutes during an isometric exercise at 30% of maximal voluntary contraction (Jamar®). At rest, the FH+ and FH- groups present similar mean blood pressure (83 ± 7 versus 83 ± 5 mmHg, p = 0.96), heart rate (69 ± 8 bpm versus 66 ± 7 bpm, p = 0.18), forearm blood flow (3 ± 1 mL/min/100 mL versus 2.7 ± 1 mL/min/100 mL, p = 0.16), and peripheral vascular resistance (30 ± 9 units versus 34±9 units, p = 0.21), respectively. Both groups showed a significant and similar increase in mean blood pressure (∆ = 15 ± 7 mmHg versus 14 ± 7 mmHg, p = 0.86), heart rate (∆ = 12 ± 8 bpm versus 13 ± 7 bpm, p = 0.86), and forearm blood flow (∆ = 0.8 ± 1.2 mL/min/100 mL versus 1.4 ± 1.1 mL/min/100 mL, p = 0.25), respectively, during exercise. However, individuals in the FH+ group showed no reduction in peripheral vascular resistance during exercise, which was observed in the FH- group (∆ = -0.4 ± 8.6 units versus -7.2 ± 6.3 units, p = 0.03). Normotensive individuals with a family history of hypertension present an impaired peripheral vascular resistance response to exercise. O histórico familiar para hipertensão arterial está relacionado a anormalidades vasculares e autonômicas, bem como disfunções no comportamento neuro-hemodinâmico durante o exerc

  7. Are there two forms of isometric muscle action? Results of the experimental study support a distinction between a holding and a pushing isometric muscle function.

    PubMed

    Schaefer, Laura V; Bittmann, Frank N

    2017-01-01

    In isometric muscle function, there are subjectively two different modes of performance: one can either hold isometrically - thus resist an impacting force - or push isometrically - therefore work against a stable resistance. The purpose of this study is to investigate whether or not two different isometric muscle actions - the holding vs. pushing one (HIMA vs PIMA) - can be distinguished by objective parameters. Ten subjects performed two different measuring modes at 80% of MVC realized by a special pneumatic system. During HIMA the subject had to resist the defined impacting force of the pneumatic system in an isometric position, whereby the force of the cylinder works in direction of elbow flexion against the subject. During PIMA the subject worked isometrically in direction of elbow extension against a stable position of the system. The signals of pressure, force, acceleration and mechanomyography/-tendography (MMG/MTG) of the elbow extensor (MMGtri/MTGtri) and the abdominal muscle (MMGobl) were recorded and evaluated concerning the duration of maintaining the force level (force endurance) and the characteristics of MMG-/MTG-signals. Statistical group differences comparing HIMA vs. PIMA were estimated using SPSS. Significant differences between HIMA and PIMA were especially apparent regarding the force endurance: During HIMA the subjects showed a decisively shorter time of stable isometric position (19 ± 8 s) in comparison with PIMA (41 ± 24 s; p  = .005). In addition, during PIMA the longest isometric plateau amounted to 59.4% of the overall duration time of isometric measuring, during HIMA it lasted 31.6% ( p  = .000). The frequency of MMG/MTG did not show significant differences. The power in the frequency ranges of 8-15 Hz and 10-29 Hz was significantly higher in the MTGtri performing HIMA compared to PIMA (but not for the MMGs). The amplitude of MMG/MTG did not show any significant difference considering the whole measurement. However

  8. Predicting non-isometric fatigue induced by electrical stimulation pulse trains as a function of pulse duration

    PubMed Central

    2013-01-01

    Background Our previous model of the non-isometric muscle fatigue that occurs during repetitive functional electrical stimulation included models of force, motion, and fatigue and accounted for applied load but not stimulation pulse duration. Our objectives were to: 1) further develop, 2) validate, and 3) present outcome measures for a non-isometric fatigue model that can predict the effect of a range of pulse durations on muscle fatigue. Methods A computer-controlled stimulator sent electrical pulses to electrodes on the thighs of 25 able-bodied human subjects. Isometric and non-isometric non-fatiguing and fatiguing knee torques and/or angles were measured. Pulse duration (170–600 μs) was the independent variable. Measurements were divided into parameter identification and model validation subsets. Results The fatigue model was simplified by removing two of three non-isometric parameters. The third remained a function of other model parameters. Between 66% and 77% of the variability in the angle measurements was explained by the new model. Conclusion Muscle fatigue in response to different stimulation pulse durations can be predicted during non-isometric repetitive contractions. PMID:23374142

  9. Contribution of hamstring fatigue to quadriceps inhibition following lumbar extension exercise.

    PubMed

    Hart, Joseph M; Kerrigan, D Casey; Fritz, Julie M; Saliba, Ethan N; Gansneder, Bruce; Ingersoll, Christopher D

    2006-01-01

    The purpose of this study was to determine the contribution of hamstrings and quadriceps fatigue to quadriceps inhibition following lumbar extension exercise. Regression models were calculated consisting of the outcome variable: quadriceps inhibition and predictor variables: change in EMG median frequency in the quadriceps and hamstrings during lumbar fatiguing exercise. Twenty-five subjects with a history of low back pain were matched by gender, height and mass to 25 healthy controls. Subjects performed two sets of fatiguing isometric lumbar extension exercise until mild (set 1) and moderate (set 2) fatigue of the lumbar paraspinals. Quadriceps and hamstring EMG median frequency were measured while subjects performed fatiguing exercise. A burst of electrical stimuli was superimposed while subjects performed an isometric maximal quadriceps contraction to estimate quadriceps inhibition after each exercise set. Results indicate the change in hamstring median frequency explained variance in quadriceps inhibition following the exercise sets in the history of low back pain group only. Change in quadriceps median frequency explained variance in quadriceps inhibition following the first exercise set in the control group only. In conclusion, persons with a history of low back pain whose quadriceps become inhibited following lumbar paraspinal exercise may be adapting to the fatigue by using their hamstring muscles more than controls. Key PointsA neuromuscular relationship between the lumbar paraspinals and quadriceps while performing lumbar extension exercise may be influenced by hamstring muscle fatigue.QI following lumbar extension exercise in persons with a history of LBP group may involve significant contribution from the hamstring muscle group.More hamstring muscle contribution may be a necessary adaptation in the history of LBP group due to weaker and more fatigable lumbar extensors.

  10. Isometric handgrip training reduces arterial pressure at rest without changes in sympathetic nerve activity

    NASA Technical Reports Server (NTRS)

    Ray, C. A.; Carrasco, D. I.

    2000-01-01

    The purpose of this study was to determine whether isometric handgrip (IHG) training reduces arterial pressure and whether reductions in muscle sympathetic nerve activity (MSNA) mediate this drop in arterial pressure. Normotensive subjects were assigned to training (n = 9), sham training (n = 7), or control (n = 8) groups. The training protocol consisted of four 3-min bouts of IHG exercise at 30% of maximal voluntary contraction (MVC) separated by 5-min rest periods. Training was performed four times per week for 5 wk. Subjects' resting arterial pressure and heart rate were measured three times on 3 consecutive days before and after training, with resting MSNA (peroneal nerve) recorded on the third day. Additionally, subjects performed IHG exercise at 30% of MVC to fatigue followed by muscle ischemia. In the trained group, resting diastolic (67 +/- 1 to 62 +/- 1 mmHg) and mean arterial pressure (86 +/- 1 to 82 +/- 1 mmHg) significantly decreased, whereas systolic arterial pressure (116 +/- 3 to 113 +/- 2 mmHg), heart rate (67 +/- 4 to 66 +/- 4 beats/min), and MSNA (14 +/- 2 to 15 +/- 2 bursts/min) did not significantly change following training. MSNA and cardiovascular responses to exercise and postexercise muscle ischemia were unchanged by training. There were no significant changes in any variables for the sham training and control groups. The results indicate that IHG training is an effective nonpharmacological intervention in lowering arterial pressure.

  11. 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.

  12. Intramuscular fiber conduction velocity, isometric force and explosive performance.

    PubMed

    Methenitis, Spyridon; Terzis, Gerasimos; Zaras, Nikolaos; Stasinaki, Angeliki-Nikoletta; Karandreas, Nikolaos

    2016-06-01

    Conduction of electrical signals along the surface of muscle fibers is acknowledged as an essential neuromuscular component which is linked with muscle force production. However, it remains unclear whether muscle fiber conduction velocity (MFCV) is also linked with explosive performance. The aim of the present study was to investigate the relationship between vastus lateralis MFCV and countermovement jumping performance, the rate of force development and maximum isometric force. Fifteen moderately-trained young females performed countermovement jumps as well as an isometric leg press test in order to determine the rate of force development and maximum isometric force. Vastus lateralis MFCV was measured with intramuscular microelectrodes at rest on a different occasion. Maximum MFCV was significantly correlated with maximum isometric force (r = 0.66, p < 0.01), nevertheless even closer with the leg press rate of force development at 100 ms, 150 ms, 200 ms, and 250 ms (r = 0.85, r = 0.89, r = 0.91, r = 0.92, respectively, p < 0.01). Similarly, mean MFCV and type II MFCV were better correlated with the rate of force development than with maximum isometric leg press force. Lower, but significant correlations were found between mean MFCV and countermovement jump power (r = 0.65, p < 0.01). These data suggest that muscle fiber conduction velocity is better linked with the rate of force development than with isometric force, perhaps because conduction velocity is higher in the larger and fastest muscle fibers which are recognized to contribute to explosive actions.

  13. Loading, electromyograph, and motion during exercise

    NASA Technical Reports Server (NTRS)

    Todd, Beth A.

    1993-01-01

    A bicycle ergometer system has been developed to determine forces acting in specific muscles and muscle groups for both cycling and isometric exercise. The bicycle has been instrumented with encoders, accelerometers, and load cells. A harnessing system has been developed to keep subjects in place during isometric exercise. EMG data will also be collected with electrodes attached to various muscles on the subject's leg. Data has been collected for static loading and will be collected for cycling in both an earth-based laboratory and on the KC-135. Once the data is analyzed, the forces will be entered into finite element models of bones of the lower extremities. A finite element model of the tibia-fibula has been generated from the experimental subject's MRI data. The linear elastic isoparametric brick elements representing the bones are connected by linear elastic isoparametric shell elements placed at the locations of ligaments. Models will be generated for the calcaneus and the femur. Material properties for the various tissues will be taken from the literature. The experimentally determined muscle forces will be applied to the models to determine the stress distribution which is created in the bones.

  14. The efficacy of Sustained Natural Apophyseal Glides with and without Isometric Exercise Training in Non-specific Neck Pain.

    PubMed

    Ali, Abid; Shakil-Ur-Rehman, Syed; Sibtain, Fozia

    2014-07-01

    To determine the efficacy of Sustained Natural Apophyseal Glides (SNAGs) with and without Isometric Exercise Training Program (IETP) in Non-specific Neck Pain (NSNP) Methods: This randomized control trial of one year duration was conducted at out-patient department of Physiotherapy and Rehabilitation, Khyber Teaching Hospital (KTH) Peshawar, Pakistan from July 2012 to June 2013. The sample of 102 patients of NSNP were randomly selected through simple random sampling technique, and placed into two groups. The SNAGs manual physical therapy technique with IETP was applied on 51 patients in group A and SNAGs manual physical therapy techniques was applied alone on 51 patients in group B. The duration of intervention was 6 weeks, at 4 times per week. The Neck Disability Index (NDI) and Visual Analog Scale (VAS) for neck pain were assessment tools used for all patients before and after 6 weeks of physical therapy intervention. All the patients were assessed through NDI and VAS before intervention and at the completion of 6 weeks program. The data of all 102 was analyzed by SPSS-20 and statistical test was applied at 95% level of significance determine the efficacy of both the treatments interventions and compare with each other. The patients in group A, treated with SNAGs and followed by IETP for 6 weeks, demonstrated more improvement in pain and physical activity as assessed by VAS (p=0.013) and NDI (p=0.003), as compared to the patients treated with SNAGS alone, as pain and function assessed by VAS (p=0.047) and NDI (p=0.164). In group A the NDI score improved from 40 to 15 and VAS from 7 to 4, while in group B the NDI score improved from 42 to 30 and VAS from 7 to 4. Patients with non-specific neck pain treated with SNAGs manual physical therapy techniques and followed by IETP was more effective in reduction of pain and enhancement of function, as compared to those patients treated with SNAGs manual physical therapy techniques alone.

  15. Isometric deformations of planar quadrilaterals with constant index

    SciTech Connect

    Zaputryaeva, E S

    We consider isometric deformations (motions) of polygons (so-called carpenter's rule problem) in the case of self-intersecting polygons with the additional condition that the index of the polygon is preserved by the motion. We provide general information about isometric deformations of planar polygons and give a complete solution of the carpenter's problem for quadrilaterals. Bibliography: 17 titles.

  16. Effect of cold pressor stimulation (4 degrees C) on human masseter muscle haemodynamics during and after sustained isometric contraction.

    PubMed

    Maekawa, K; Kuboki, T; Yamashita, A; Clark, G T

    1999-11-01

    The effect of cold pressor (CP) stimulation and sustained isometric contraction on the blood volume of the right masseter muscle was examined in seven healthy males, who performed 1 min of isometric jaw clenching at 50% of their maximum voluntary contraction without, with and again without a 4 degrees C CP stimulation. Total haemoglobin was measured in the masseter before, during and after the contraction task using near-infrared spectroscopy. CP stimulation during the isometric contraction diminished the magnitude of the contraction-induced decrease of blood volume when compared to the trials without CP stimulation. However, in the immediate post-contraction period (while the CP stimulation was still in place), no increase in blood volume above the usual post-contraction hyperaemia was evident. Once the CP stimulation had been removed, there was a clear decrease (faster return to baseline) in the vasodilation occurring in the post-contraction period. This diminished period of vasodilation occurred in spite of the fact that the vascular resistance (blood pressure) and heart rate were still substantially elevated by the CP effect during this same period. These data suggest that the strong CP stimulation produced a biphasic response. First, there was an early-onset strong vasodilation (during CP), which was followed by a period of diminished vasodilation, suggesting that an active, but delayed, vasoconstrictive drive may be induced by the CP stimulus.

  17. Physiotherapy exercise programmes: are instructional exercise sheets effective?

    PubMed

    Smith, Jo; Lewis, Jeremy; Prichard, Diana

    2005-01-01

    Effective compliance with physiotherapy exercises is only possible if patients remember the exercises accurately. The purpose of this study was to assess how well elderly in-patients remembered simple physiotherapy exercises, by comparing the ability to accurately reproduce a set of exercises in a group of patients that had received a written exercise sheet, with a group that had not. The study also aimed to investigate the relationship between memory for exercises and cognition. Sixty-four in-patients in an acute hospital were taught 3 exercises. Half of the subjects were randomised to receive exercise sheets to reinforce the teaching (Group 1). The rest of the subjects did not receive this memory aid (Group 2). Two to three days later subjects were asked to demonstrate their exercises. The accurate recall of the exercises was scored using a new assessment scale with a maximum score of 24. The mean exercise score was 17.19 for group 1 (SD = 5.91) and 16.24 for Group 2 (SD = 6.01). There was no significant difference in exercise score between groups (Mann Whitney U test p = 0.44). There was a statistically significant small positive correlation between exercise score and cognition (tau = 0.263). The study showed that older adult in-patients do not remember physiotherapy exercises effectively after a single teaching session and that their memory is not significantly improved by provision of an exercise sheet.

  18. Effect of Lumbar Progressive Resistance Exercise on Lumbar Muscular Strength and Core Muscular Endurance in Soldiers.

    PubMed

    Mayer, John M; Childs, John D; Neilson, Brett D; Chen, Henian; Koppenhaver, Shane L; Quillen, William S

    2016-11-01

    Low back pain is common, costly, and disabling for active duty military personnel and veterans. The evidence is unclear on which management approaches are most effective. The purpose of this study was to assess the effectiveness of lumbar extensor high-intensity progressive resistance exercise (HIPRE) training versus control on improving lumbar extension muscular strength and core muscular endurance in soldiers. A randomized controlled trial was conducted with active duty U.S. Army Soldiers (n = 582) in combat medic training at Fort Sam Houston, Texas. Soldiers were randomized by platoon to receive the experimental intervention (lumbar extensor HIPRE training, n = 298) or control intervention (core stabilization exercise training, n = 284) at one set, one time per week, for 11 weeks. Lumbar extension muscular strength and core muscular endurance were assessed before and after the intervention period. At 11-week follow-up, lumbar extension muscular strength was 9.7% greater (p = 0.001) for HIPRE compared with control. No improvements in core muscular endurance were observed for HIPRE or control. Lumbar extensor HIPRE training is effective to improve isometric lumbar extension muscular strength in U.S. Army Soldiers. Research is needed to explore the clinical relevance of these gains. Reprint & Copyright © 2016 Association of Military Surgeons of the U.S.

  19. Exercise-induced Hypoalgesia in People With Knee Osteoarthritis With Normal and Abnormal Conditioned Pain Modulation.

    PubMed

    Fingleton, Caitríona; Smart, Keith M; Doody, Catherine M

    2017-05-01

    Normal efficiency of exercise-induced hypoalgesia (EIH) has been demonstrated in people with knee osteoarthritis (OA), while recent evidence suggests that EIH may be associated with features of pain sensitization such as abnormal conditioned pain modulation (CPM). The aim of this study was to investigate whether people with knee OA with abnormal CPM have dysfunctional EIH compared with those with normal CPM and pain-free controls. Forty peoples with knee OA were subdivided into groups with abnormal and normal CPM, as determined by a decrease/increase in pressure pain thresholds (PPTs) following the cold pressor test. Abnormal CPM (n=19), normal CPM (n=21), and control participants (n=20) underwent PPT testing before, during, and after aerobic and isometric exercise protocols. Between-group differences were analyzed using repeated-measures analysis of variance and within-group differences were analyzed using Wilcoxon signed-rank tests. Significant differences were demonstrated between groups for changes in PPTs postaerobic (F2,55=4.860; P=0.011) and isometric (F2,57=4.727; P=0.013) exercise, with significant decreases in PPTs demonstrated during and postexercise in the abnormal CPM group (P<0.05), and significant increases in PPTs shown during and postexercise in the normal CPM and control groups (P<0.05). Results are suggestive of dysfunctional EIH in response to aerobic and isometric exercise in knee OA patients with abnormal CPM, and normal function of EIH in knee OA patients with an efficient CPM response. Identification of people with knee OA with inefficient endogenous pain modulation may allow for a more individualized and graded approach to exercises in these individuals.

  20. Stretch-activated ion channel blockade attenuates adaptations to eccentric exercise.

    PubMed

    Butterfield, Timothy A; Best, Thomas M

    2009-02-01

    The purpose of this study was to test the hypothesis that stretch-activated ion channel (SAC) function is essential for the repeated bout effect (RBE) in skeletal muscle. Specifically, we investigated if daily injections of streptomycin (a known SAC blocker) would abrogate the muscle's adaptive resistance to the damaging effects of eccentric exercise over a 4-wk period. Furthermore, we hypothesized that the lack of an RBE would be due to the lack of functional adaptations that typically result from repeated bouts of eccentric exercise, including increased peak isometric torque, muscle hypertrophy, and rightward shift of the torque-angle relationship. Twelve New Zealand white rabbits were each subjected to 12 bouts of eccentric exercise over a 4-wk period while receiving either daily injections of streptomycin or sham injections. Although blocking the SAC function completely eliminated the expected adaptive response in biomechanical parameters during the exercise regimen, there remained evidence of an acquired RBE, albeit with an attenuated response when compared with the muscles with intact SAC function. Blocking sarcolemmal SAC eliminates functional adaptations of muscle after eccentric exercise. In the absence of SAC function, muscles subjected to chronic eccentric exercise still exhibit some degree of the RBE. As such, it appears that the signaling cascade that results in functional, biomechanical adaptations associated with the RBE during eccentric exercise is dependent upon intact SAC function.

  1. Coronary Exercise Hyperemia Is Impaired in Patients with Peripheral Arterial Disease.

    PubMed

    Ross, Amanda J; Gao, Zhaohui; Luck, Jonathan Carter; Blaha, Cheryl A; Cauffman, Aimee E; Aziz, Faisal; Radtka, John F; Proctor, David N; Leuenberger, Urs A; Sinoway, Lawrence I; Muller, Matthew D

    2017-01-01

    Peripheral arterial disease (PAD) is an atherosclerotic vascular disease that affects over 200 million people worldwide. The hallmark of PAD is ischemic leg pain and this condition is also associated with an augmented blood pressure response to exercise, impaired vascular function, and high risk of myocardial infarction and cardiovascular mortality. In this study, we tested the hypothesis that coronary exercise hyperemia is impaired in PAD. Twelve patients with PAD and no overt coronary disease (65 ± 2 years, 7 men) and 15 healthy control subjects (64 ± 2 years, 9 men) performed supine plantar flexion exercise (30 contractions/min, increasing workload). A subset of subjects (n = 7 PAD, n = 8 healthy) also performed isometric handgrip exercise (40% of maximum voluntary contraction to fatigue). Coronary blood velocity in the left anterior descending artery was measured by transthoracic Doppler echocardiography; blood pressure and heart rate were monitored continuously. Coronary blood velocity responses to 4 min of plantar flexion exercise (PAD: Δ2.4 ± 1.2, healthy: Δ6.0 ± 1.6 cm/sec, P = 0.039) and isometric handgrip exercise (PAD: Δ8.3 ± 4.2, healthy: Δ16.9 ± 3.6, P = 0.033) were attenuated in PAD patients. These data indicate that coronary exercise hyperemia is impaired in PAD, which may predispose these patients to myocardial ischemia. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. Reliability of isometric subtalar pronator and supinator strength testing.

    PubMed

    Hagen, Marco; Lahner, Matthias; Winhuysen, Martin; Maiwald, Christian

    2015-01-01

    Due to the specific anatomy of the subtalar joint with its oblique axis, isometric pronator and supinator strength is not well documented. The purpose of this study was to determine intra- and between-session reliability of pronator and supinator strength and lower leg muscle activity measurements during maximum voluntary isometric contractions (MVIC). Pronator and supinator peak torques (PT), with and without supplementary visual muscle strength biofeedback (FB), and muscular activities of peroneus longus (PL) and tibialis anterior (TA) were assessed twice 3 days apart by the same examiner in 21 healthy young male adults (mean age: 27.6 years; SD = 3.9). Limits of agreement (LoA) and minimum detectable change (MDC) were evaluated. By applying FB, reliability of both pronator and supinator PT was improved: LoA were reduced from 32% to 26% and from 20% to 18% and MDC from 20% to 15% and from 16% to 12% in supinator and pronator PT, respectively. Learning effects in pronator and supinator PT (p < 0.05), which were present without FB, were eliminated using FB. Except for TA during pronation, muscle activities showed low reliability indicated by LoA of 51% to 79%. Using supplementary biofeedback, isometric subtalar pronator and supinator strength testing is reliable in healthy subjects. LoA of 18% and 26% have to be exceeded for pronator and supinator PT, respectively, to detect relevant effects in repeated measures.

  3. Trunk isometric force production parameters during erector spinae muscle vibration at different frequencies

    PubMed Central

    2013-01-01

    Background Vibration is known to alter proprioceptive afferents and create a tonic vibration reflex. The control of force and its variability are often considered determinants of motor performance and neuromuscular control. However, the effect of vibration on paraspinal muscle control and force production remains to be determined. Methods Twenty-one healthy adults were asked to perform isometric trunk flexion and extension torque at 60% of their maximal voluntary isometric contraction, under three different vibration conditions: no vibration, vibration frequencies of 30 Hz and 80 Hz. Eighteen isometric contractions were performed under each condition without any feedback. Mechanical vibrations were applied bilaterally over the lumbar erector spinae muscles while participants were in neutral standing position. Time to peak torque (TPT), variable error (VE) as well as constant error (CE) and absolute error (AE) in peak torque were calculated and compared between conditions. Results The main finding suggests that erector spinae muscle vibration significantly decreases the accuracy in a trunk extension isometric force reproduction task. There was no difference between both vibration frequencies with regard to force production parameters. Antagonist muscles do not seem to be directly affected by vibration stimulation when performing a trunk isometric task. Conclusions The results suggest that acute erector spinae muscle vibration interferes with torque generation sequence of the trunk by distorting proprioceptive information in healthy participants. PMID:23919578

  4. The Impact of Exercise on Statin-Associated Skeletal Muscle Myopathy

    PubMed Central

    Chung, Hae R.; Vakil, Mayand; Munroe, Michael; Parikh, Alay; Meador, Benjamin M.; Wu, Pei T.; Jeong, Jin H.; Woods, Jeffrey A.; Wilund, Kenneth R.; Boppart, Marni D.

    2016-01-01

    HMG-CoA reductase inhibitors (statins) are the most effective pharmacological means of reducing cardiovascular disease risk. The most common side effect of statin use is skeletal muscle myopathy, which may be exacerbated by exercise. Hypercholesterolemia and training status are factors that are rarely considered in the progression of myopathy. The purpose of this study was to determine the extent to which acute and chronic exercise can influence statin-induced myopathy in hypercholesterolemic (ApoE-/-) mice. Mice either received daily injections of saline or simvastatin (20 mg/kg) while: 1) remaining sedentary (Sed), 2) engaging in daily exercise for two weeks (novel, Nov), or 3) engaging in daily exercise for two weeks after a brief period of training (accustomed, Acct) (2x3 design, n = 60). Cholesterol, activity, strength, and indices of myofiber damage and atrophy were assessed. Running wheel activity declined in both exercise groups receiving statins (statin x time interaction, p<0.05). Cholesterol, grip strength, and maximal isometric force were significantly lower in all groups following statin treatment (statin main effect, p<0.05). Mitochondrial content and myofiber size were increased and 4-HNE was decreased by exercise (statin x exercise interaction, p<0.05), and these beneficial effects were abrogated by statin treatment. Exercise (Acct and Nov) increased atrogin-1 mRNA in combination with statin treatment, yet enhanced fiber damage or atrophy was not observed. The results from this study suggest that exercise (Nov, Acct) does not exacerbate statin-induced myopathy in ApoE-/- mice, yet statin treatment reduces activity in a manner that prevents muscle from mounting a beneficial adaptive response to training. PMID:27936249

  5. Acute Effects of Partial-Body Cryotherapy on Isometric Strength: Maximum Handgrip Strength Evaluation.

    PubMed

    De Nardi, Massimo; Pizzigalli, Luisa; Benis, Roberto; Caffaro, Federica; Micheletti Cremasco, Margherita

    2017-12-01

    De Nardi, M, Pizzigalli, L, Benis, R, Caffaro, F, and Cremasco, MM. Acute effects of partial-body cryotherapy on isometric strength: maximum handgrip strength evaluation. J Strength Cond Res 31(12): 3497-3502, 2017-The aim of the study was to evaluate the influence of a single partial-body cryotherapy (PBC) session on the maximum handgrip strength (JAMAR Hydraulic Hand dynamometer). Two hundred healthy adults were randomized into a PBC group and a control group (50 men and 50 women in each group). After the initial handgrip strength test (T0), the experimental group performed a 150-second session of PBC (temperature range between -130 and -160° C), whereas the control group stayed in a thermo neutral room (22.0 ± 0.5° C). Immediately after, both groups performed another handgrip strength test (T1). Data underlined that both groups showed an increase in handgrip strength values, especially the experimental group (Control: T0 = 39.48 kg, T1 = 40.01 kg; PBC: T0 = 39.61 kg, T1 = 41.34 kg). The analysis also reported a statistical effect related to gender (F = 491.99, P ≤ 0.05), with women showing lower handgrip strength values compared with men (women = 30.43 kg, men = 52.27 kg). Findings provide the first evidence that a single session of PBC leads to the improvement of muscle strength in healthy people. The results of the study imply that PBC could be performed also before a training session or a sport competition, to increase hand isometric strength.

  6. The effects of therapeutic hip exercise with abdominal core activation on recruitment of the hip muscles.

    PubMed

    Chan, Mandy Ky; Chow, Ka Wai; Lai, Alfred Ys; Mak, Noble Kc; Sze, Jason Ch; Tsang, Sharon Mh

    2017-07-21

    Core stabilization has been utilized for rehabilitation and prevention of lower limb musculoskeletal injuries. Previous studies showed that activation of the abdominal core muscles enhanced the hip muscle activity in hip extension and abduction exercises. However, the lack of the direct measurement and quantification of the activation level of the abdominal core muscles during the execution of the hip exercises affect the level of evidence to substantiate the proposed application of core exercises to promote training and rehabilitation outcome of the hip region. The aim of the present study was to examine the effects of abdominal core activation, which is monitored directly by surface electromyography (EMG), on hip muscle activation while performing different hip exercises, and to explore whether participant characteristics such as gender, physical activity level and contractile properties of muscles, which is assessed by tensiomyography (TMG), have confounding effect to the activation of hip muscles in enhanced core condition. Surface EMG of bilateral internal obliques (IO), upper gluteus maximus (UGMax), lower gluteus maximus (LGMax), gluteus medius (GMed) and biceps femoris (BF) of dominant leg was recorded in 20 young healthy subjects while performing 3 hip exercises: Clam, side-lying hip abduction (HABD), and prone hip extension (PHE) in 2 conditions: natural core activation (NC) and enhanced core activation (CO). EMG signals normalized to percentage of maximal voluntary isometric contraction (%MVIC) were compared between two core conditions with the threshold of the enhanced abdominal core condition defined as >20%MVIC of IO. Enhanced abdominal core activation has significantly promoted the activation level of GMed in all phases of clam exercise (P < 0.05), and UGMax in all phases of PHE exercise (P < 0.05), LGMax in eccentric phases of all 3 exercises (P < 0.05), and BF in all phases of all 3 exercises except the eccentric phase of PHE exercise (P

  7. Open versus closed kinetic chain exercises for patellar chondromalacia.

    PubMed

    Bakhtiary, A H; Fatemi, E

    2008-02-01

    Conservative treatment of patellar chondromalacia has been the subject of several studies. One recommended treatment is a strengthening exercise of the quadriceps muscle, which may be performed in closed or open kinetic chains. This study was designed to compare the effect of straight leg raise (SLR) and semi-squat exercises on the treatment of patellar chondromalacia, which has not been done to date. 32 female university students with a diagnosis of patellar chondromalacia were randomly assigned to two experimental groups: SLR and semi-squat exercise. Before starting exercise protocols, Q angle, maximal isometric voluntary contraction force (MIVCF) of quadriceps, crepitation, circumference of thigh 5 and 10 cm above the patella and patellofemoral pain according to the visual analogue scale (VAS) were assessed. Both groups then followed a 3-week programme of quadriceps muscle strengthening exercises (SLR or semi-squat) starting with 20 exercises twice a day and increasing each session by 5 exercises every 2 days. All measurements were repeated at the end of each week and then again 2 weeks after the 3-week exercise programme. Reduced Q angle (mean differences (SD) 0.8 (0.3), p = 0.016) and crepitation (19.9 (8.5), p = 0.04), and an increase in the MIVCF of the quadriceps (15.8 (5.6), p = 0.01) and thigh circumference (1.5 (0.3), p = 0.001) were found in semi-squat group compared with SLR group. However, patellofemoral pain was decreased significantly in both groups. The results of this study indicate that semi-squat exercises (closed kinetic chain) are more effective than SLR exercise (open kinetic chain) in the treatment of patellar chondromalacia. More studies are needed to investigate the long-term effect of these types of exercise.

  8. A Pilot Study of the Head Extension Swallowing Exercise: New Method for Strengthening Swallowing-Related Muscle Activity.

    PubMed

    Oh, Jong-Chi

    2016-10-01

    This pilot study examined the effect of a new head extension swallowing exercise (HESE) on submental muscle activity and tongue strength in healthy volunteers. Fifteen young adults (10 females and 5 males) were instructed to extend their head backwards as much as possible, and while watching the ceiling, swallowed their saliva every 10 s for a duration of 20 min. Twenty-four treatments were performed over 8 weeks. The outcome variables evaluated at baseline, 4 and 8 weeks of training, and 12-week follow-up included mean and peak submental muscle activation amplitudes during normal and effortful swallowing measured via surface electromyography, and anterior and posterior isometric tongue pressures were measured with the Iowa Oral Performance Instrument. Results indicated that the muscle activation amplitudes during effortful swallowing increased significantly at 4 and 8 weeks compared to baseline (p < 0.025). However, the increases in amplitudes during normal swallowing were minor (nonsignificant) after 8 weeks compared to baseline. The isometric pressures of the tongue tip and the posterior part of the oral tongue were significantly higher at 8 weeks compared to baseline (p < 0.025). Thus, the 8-week HESE protocol significantly improved suprahyoid muscle activity during effortful swallowing as well as the isometric tongue pressures. The HESE appears effective in exercising and strengthening the suprahyoid muscles and tongue muscles in healthy participants. Although encouraging, these results need to be replicated in clinical trials for testing the therapeutic effects of the HESE in older adults and patients with dysphagia who present with decreased hyolaryngeal elevation.

  9. Exercise Training in Treatment and Rehabilitation of Hip Osteoarthritis: A 12-Week Pilot Trial

    PubMed Central

    Patil, Radhika; Karinkanta, Saija; Tokola, Kari; Kannus, Pekka

    2017-01-01

    Introduction. Osteoarthritis (OA) of the hip is one of the major causes of pain and disability in the older population. Although exercise is an effective treatment for knee OA, there is lack of evidence regarding hip OA. The aim of this trial was to test the safety and feasibility of a specifically designed exercise program in relieving hip pain and improving function in hip OA participants and to evaluate various methods to measure changes in their physical functioning. Materials and Methods. 13 women aged ≥ 65 years with hip OA were recruited in this 12-week pilot study. Results. Pain declined significantly over 30% from baseline, and joint function and health-related quality of life improved slightly. Objective assessment of physical functioning showed statistically significant improvement in the maximal isometric leg extensor strength by 20% and in the hip extension range of motion by 30%. Conclusions. The exercise program was found to be safe and feasible. The present evidence indicates that the exercise program is effective in the short term. However, adequate powered RCTs are needed to determine effects of long-term exercise therapy on pain and progression of hip OA. PMID:28116214

  10. Age-Related Variability in Tongue Pressure Patterns for Maximum Isometric and Saliva Swallowing Tasks

    PubMed Central

    Peladeau-Pigeon, Melanie

    2017-01-01

    Purpose The ability to generate tongue pressure plays a major role in bolus transport in swallowing. In studies of motor control, stability or variability of movement is a feature that changes with age, disease, task complexity, and perturbation. In this study, we explored whether age and tongue strength influence the stability of the tongue pressure generation pattern during isometric and swallowing tasks in healthy volunteers. Method Tongue pressure data, collected using the Iowa Oral Performance Instrument, were analyzed from 84 participants in sex-balanced and decade age-group strata. Tasks included maximum anterior and posterior isometric pressures and regular-effort saliva swallows. The cyclic spatiotemporal index (cSTI) was used to capture stability (vs. variability) in patterns of pressure generation. Mixed-model repeated measures analyses of covariance were performed separately for each task (anterior and posterior isometric pressures, saliva swallows) with between-participant factors of age group and sex, a within-participant factor of task repetition, and a continuous covariate of tongue strength. Results Neither age group nor sex effects were found. There was no significant relationship between tongue strength and the cSTI on the anterior isometric tongue pressure task (r = −.11). For the posterior isometric tongue pressure task, a significant negative correlation (r = −.395) was found between tongue strength and the cSTI. The opposite pattern of a significant positive correlation (r = .29) between tongue strength and the cSTI was seen for the saliva swallow task. Conclusions Tongue pressure generation patterns appear highly stable across repeated maximum isometric and saliva swallow tasks, despite advancing age. Greater pattern variability is seen with weaker posterior isometric pressures. Overall, saliva swallows had the lowest pressure amplitudes and highest pressure pattern variability as measured by the cSTI. PMID:29114767

  11. A comparison of different vibration exercise techniques on neuromuscular performance.

    PubMed

    García-Gutiérrez, M T; Rhea, M R; Marín, P J

    2014-09-01

    The first purpose of this study was to determine the effects of whole-body vibration (WBV) exercise during an isometric hand-grip exercise. The second purpose was to evaluate whether more than one vibratory focus would evoke an increase in the effects evoked by only one vibratory focus. The present study investigated whether WBV exposure during 10 repetitions of a handgrip dynamometer while standing on a WBV platform. Twenty-eight recreationally active university students completed 3 different test conditions, in random order: 1) grip dynamometer exercise with superimposed WBV and contralateral arm vibration (WBV+AV); 2) superimposed arm vibration only (AV); 3) grip dynamometer exercise without vibration (Control). The hand grip strength was slightly higher in the WBV condition as compared to the Control and AV conditions (1.1% and 3.6%, p>0.05, respectively). A main effect of the EMGrms of extensor digitorum muscle (ED) was observed indicating that the WBV+AV condition produced a lower co-activation of ED during a flexor digital task than the Control and AV (p<0.05) conditions. The application of WBV+AV may acutely increase muscle coordination and decreases the coactivation of ED. Furthermore, the muscle EMGrms showed increases in activation near the vibratory focus in both upper- and lower-body.

  12. Screen time viewing behaviors and isometric trunk muscle strength in youth.

    PubMed

    Grøntved, Anders; Ried-Larsen, Mathias; Froberg, Karsten; Wedderkopp, Niels; Brage, Søren; Kristensen, Peter Lund; Andersen, Lars Bo; Møller, Niels Christian

    2013-10-01

    The objective of this study was to examine the association of screen time viewing behavior with isometric trunk muscle strength in youth. A cross-sectional study was carried out including 606 adolescents (14-16 yr old) participating in the Danish European Youth Heart Study, a population-based study with assessments conducted in either 1997/1998 or 2003/2004. Maximal voluntary contractions during isometric back extension and abdominal flexion were determined using a strain gauge dynamometer, and cardiorespiratory fitness (CRF) was obtained using a maximal cycle ergometer test. TV viewing time, computer use, and other lifestyle behaviors were obtained by self-report. Analyses of association of screen use behaviors with isometric trunk muscle strength were carried out using multivariable adjusted linear regression. The mean (SD) isometric strength was 0.87 (0.16) N·kg-1. TV viewing, computer use, and total screen time use were inversely associated with isometric trunk muscle strength in analyses adjusted for lifestyle and sociodemographic factors. After further adjustment for CRF and waist circumference, associations remained significant for computer use and total screen time, but TV viewing was only marginally associated with muscle strength after these additional adjustments (-0.05 SD (95% confidence interval, -0.11 to 0.005) difference in strength per 1 h·d-1 difference in TV viewing time, P = 0.08). Each 1 h·d-1 difference in total screen time use was associated with -0.09 SD (95% confidence interval, -0.14 to -0.04) lower isometric trunk muscle strength in the fully adjusted model (P = 0.001). There were no indications that the association of screen time use with isometric trunk muscle strength was attenuated among highly fit individuals (P = 0.91 for CRF by screen time interaction). Screen time use was inversely associated with isometric trunk muscle strength independent of CRF and other confounding factors.

  13. Strength and Cardiorespiratory Exercise Rehabilitation for Severely Burned Patients During Intensive Care Units: A Survey of Practice.

    PubMed

    Cambiaso-Daniel, Janos; Parry, Ingrid; Rivas, Eric; Kemp-Offenberg, Jennifer; Sen, Soman; Rizzo, Julie A; Serghiou, Michael A; Kowalske, Karen; Wolf, Steven E; Herndon, David N; Suman, Oscar E

    2018-03-22

    Minimizing the deconditioning of burn injury through early rehabilitation programs (RP) in the intensive care unit (ICU) is of importance for improving the recovery time. The aim of this study was to assess current standard of care (SOC) for early ICU exercise programs in major burn centers. We designed a survey investigating exercise RP on the ICU for burn patients with >30% total burned surface area. The survey was composed of 23 questions and submitted electronically via SurveyMonkey® to six major (pediatric and adult) burn centers in Texas and California. All centers responded and reported exercise as part of their RP on the ICU. The characteristics of exercises implemented were not uniform. All centers reported to perform resistive and aerobic exercises but only 83% reported isotonic and isometric exercises. Determination of intensity of exercise varied with 50% of centers using patient tolerance and 17% using vital signs. Frequency of isotonic, isometric, aerobic, and resistive exercise was reported as daily by 80%, 80%, 83%, and 50% of centers, respectively. Duration for all types of exercises was extremely variable. Mobilization was used as a form of exercise by 100% of burn centers. Our results demonstrate that although early RP seem to be integral during burn survivor's ICU stay, no SOC exists. Moreover, early RP are inconsistently administered and large variations exist in frequency, intensity, duration, and type of exercise. Thus, future prospective studies investigating the various components of exercise interventions are needed to establish a SOC and determine how and if early exercise benefits the burn survivor.

  14. Production of isometric forces during sustained acceleration.

    PubMed

    Sand, D P; Girgenrath, M; Bock, O; Pongratz, H

    2003-06-01

    The operation of high-performance aircraft requires pilots to apply finely graded forces on controls. Since they are often exposed to high levels of acceleration in flight, we investigated to what extent this ability is degraded in such an environment. Twelve healthy non-pilot volunteers were seated in the gondola of a centrifuge and their performance was tested at normal gravity (1 G) and while exposed to sustained forces of 1.5 G and 3 G oriented from head to foot (+Gz). Using an isometric joystick, they attempted to produce force vectors with specific lengths and directions commanded in random order by a visual display. Acceleration had substantial effects on the magnitude of produced force. Compared with 1 G, maximum produced force was about 2 N higher at 1.5 G and about 10 N higher at 3 G. The size of this effect was constant across the different magnitudes, but varied with the direction of the prescribed force. Acceleration degrades control of force production. This finding may indicate that the motor system misinterprets the unusual gravitoinertial environment and/or that proprioceptive feedback is degraded due to increased muscle tone. The production of excessive isometric force could affect the safe operation of high-performance aircraft.

  15. Probing disorder in isometric pyrochlore and related complex oxides

    NASA Astrophysics Data System (ADS)

    Shamblin, Jacob; Feygenson, Mikhail; Neuefeind, Joerg; Tracy, Cameron L.; Zhang, Fuxiang; Finkeldei, Sarah; Bosbach, Dirk; Zhou, Haidong; Ewing, Rodney C.; Lang, Maik

    2016-05-01

    There has been an increased focus on understanding the energetics of structures with unconventional ordering (for example, correlated disorder that is heterogeneous across different length scales). In particular, compounds with the isometric pyrochlore structure, A2B2O7, can adopt a disordered, isometric fluorite-type structure, (A, B)4O7, under extreme conditions. Despite the importance of the disordering process there exists only a limited understanding of the role of local ordering on the energy landscape. We have used neutron total scattering to show that disordered fluorite (induced intrinsically by composition/stoichiometry or at far-from-equilibrium conditions produced by high-energy radiation) consists of a local orthorhombic structural unit that is repeated by a pseudo-translational symmetry, such that orthorhombic and isometric arrays coexist at different length scales. We also show that inversion in isometric spinel occurs by a similar process. This insight provides a new basis for understanding order-to-disorder transformations important for applications such as plutonium immobilization, fast ion conduction, and thermal barrier coatings.

  16. RESISTIVE EXERCISES IN THE DEVELOPMENT OF MUSCULAR STRENGTH AND ENDURANCE.

    ERIC Educational Resources Information Center

    BURNHAM, STAN; MCCRAW, LYNN W.

    A STUDY WAS CONCERNED WITH A COMPARISON OF ISOTONIC, ISOMETRIC, AND SPEED EXERCISE PROGRAMS AS A MEANS OF DEVELOPING MUSCLE STRENGTH, ENDURANCE, SPEED, AND POWER. SUBJECTS FOR THE INVESTIGATION WERE 93 FRESHMEN AND SOPHOMORE MEN ENROLLED IN A PHYSICAL EDUCATION CLASS. AFTER MEASUREMENT OF INITIAL STATUS IN THE ATTRIBUTES UNDER CONSIDERATION, THE…

  17. The Adaptive Range of 1/f Isometric Force Production

    ERIC Educational Resources Information Center

    Sosnoff, Jacob J.; Valantine, Andrew D.; Newell, Karl M.

    2009-01-01

    The adaptive range of 1/f dynamics in isometric force output was investigated. Participants produced isometric force to targets with predictable demands (constant and sinusoidal) and 1/f noise waveforms (white, pink, brown, and black) that also varied in the frequency bandwidth represented in the force signal (0-4 Hz, 0-8 Hz, and 0-12 Hz). The…

  18. Chronic effect of light resistance exercise after ingestion of a high-protein snack on increase of skeletal muscle mass and strength in young adults.

    PubMed

    Kato, Yushi; Sawada, Atsushi; Numao, Shigeharu; Suzuki, Masashige

    2011-01-01

    We have previously reported on the possibility that light resistance exercise performed with a high plasma amino acid concentration resulting from the ingestion of a high-protein snack (HPS; 15 g protein, 18 g sugar) 3 h after a basal meal promotes the utilization of amino acids in peripheral tissues such as muscle in both rats and humans. In the present study, we further examined the effectiveness of a daily routine involving ingestion of HPS 3 h after a basal meal and subsequent light resistance exercise (dumbbell exercise) in increasing the mass and strength of human muscle. Ten young adult males were subject to the following 3 conditions for 5 wk each, with sufficient recovery period between each condition: (1) Snack-Exercise (SE), (2) Snack-Sedentary (SS), and (3) No snack-Exercise (NE). The SE group showed a significant increase in lean body mass and total cross-sectional area (CSA) of the right forearm muscles along with a significant decrease in body fat mass. The SS group showed no change in body composition. Furthermore, the SE group showed significant increase in grip strength and isometric knee extensor muscle strength, while the SS group showed no increase in muscle strength. The NE group showed significant increase in grip strength. In conclusion, daily routine ingestion of HPS 3 h after a basal meal and subsequent light resistance exercise is effective in increasing the mass and strength of human muscle.

  19. Arg16/Gly beta2-adrenergic receptor polymorphism alters the cardiac output response to isometric exercise.

    PubMed

    Eisenach, John H; Barnes, Sunni A; Pike, Tasha L; Sokolnicki, Lynn A; Masuki, Shizue; Dietz, Niki M; Rehfeldt, Kent H; Turner, Stephen T; Joyner, Michael J

    2005-11-01

    Normotensive adults homozygous for glycine (Gly) of the Arg16/Gly beta2-adrenergic-receptor polymorphism have 1) greater forearm beta2-receptor mediated vasodilation and 2) a higher heart rate (HR) response to isometric handgrip than arginine (Arg) homozygotes. To test the hypothesis that the higher HR response in Gly16 subjects serves to maintain the pressor response [increased cardiac output (CO)] in the setting of augmented peripheral vasodilation to endogenous catecholamines, we measured continuous HR (ECG), arterial pressure (Finapres), and CO (transthoracic echocardiography) during isometric, 40% submaximal handgrip to fatigue in healthy subjects homozygous for Gly (n = 30; mean age +/- SE: 30 +/- 1.2, 13 women) and Arg (n = 17, age 30 +/- 1.6, 11 women). Resting data were similar between groups. Handgrip produced similar increases in arterial pressure and venous norepinephrine and epinephrine concentrations; however, HR increased more in the Gly group (60.1 +/- 4.3% increase from baseline vs. 45.5 +/- 3.9%, P = 0.03), and this caused CO to be higher (Gly: 7.6 +/- 0.3 l/m vs. Arg: 6.5 +/- 0.3 l/m, P = 0.03), whereas the decrease in systemic vascular resistance in the Gly group did not reach significance (P = 0.09). We conclude that Gly16 homozygotes generate a higher CO to maintain the pressor response to handgrip. The influence of polymorphic variants in the beta2-adrenergic receptor gene on the cardiovascular response to sympathoexcitation may have important implications in the development of hypertension and heart failure.

  20. Motor unit activity after eccentric exercise and muscle damage in humans.

    PubMed

    Semmler, J G

    2014-04-01

    It is well known that unaccustomed eccentric exercise leads to muscle damage and soreness, which can produce long-lasting effects on muscle function. How this muscle damage influences muscle activation is poorly understood. The purpose of this brief review is to highlight the effect of eccentric exercise on the activation of muscle by the nervous system, by examining the change in motor unit activity obtained from surface electromyography (EMG) and intramuscular recordings. Previous research shows that eccentric exercise produces unusual changes in the EMG–force relation that influences motor performance during isometric, shortening and lengthening muscle contractions and during fatiguing tasks. When examining the effect of eccentric exercise at the single motor unit level, there are substantial changes in recruitment thresholds, discharge rates, motor unit conduction velocities and synchronization, which can last for up to 1 week after eccentric exercise. Examining the time course of these changes suggests that the increased submaximal EMG after eccentric exercise most likely occurs through a decrease in motor unit conduction velocity and an increase in motor unit activity related to antagonist muscle coactivation and low-frequency fatigue. Furthermore, there is a commonly held view that eccentric exercise produces preferential damage to high-threshold motor units, but the evidence for this in humans is limited. Further research is needed to establish whether there is preferential damage to high-threshold motor units after eccentric exercise in humans, preferably by linking changes in motor unit activity with estimates of motor unit size using selective intramuscular recording techniques.

  1. On-the-Field Resistance-Tubing Exercises for Throwers: An Electromyographic Analysis

    PubMed Central

    Myers, Joseph B; Pasquale, Maria R; Laudner, Kevin G; Sell, Timothy C; Bradley, James P; Lephart, Scott M

    2005-01-01

    Context: Athletes who throw commonly use rubber-tubing resistance exercises in the field setting to assist with warm-up before throwing. Yet no researchers have described which muscles are being activated or which exercises are most effective during rubber-tubing exercises used by throwers for warm-up. Objective: To describe the effectiveness of 12 rubber-tubing resistance exercises commonly used by throwers in activating the shoulder muscles important for throwing. Design: Descriptive research design. Setting: An applied biomechanics research laboratory. Patients or Other Participants: Fifteen physically active male subjects with no history of shoulder injury. Main Outcome Measure(s): Subjects randomly performed 12 rubber-tubing resistance exercises while we assessed muscle activation of the subscapularis, supraspinatus, teres minor, and rhomboid major by indwelling electromyography. Activation of the sternal portion of the pectoralis major, anterior deltoid, middle deltoid, latissimus dorsi, serratus anterior, biceps brachii, triceps brachii, lower trapezius, and infraspinatus muscles was assessed by surface electromyography. Results: Performance of 7 exercises (external rotation at 90° of abduction, throwing deceleration, humeral flexion, humeral extension, low scapular rows, throwing acceleration, and scapular punch) resulted in the highest level of muscle activation of all muscles tested. Conclusions: These 7 exercises exhibited moderate activation (>20% maximal voluntary isometric contraction) in each muscle of the rotator cuff, the primary humeral movers, and the scapular stabilizer muscles. The results suggest that these exercises are most effective in activating the muscles important to the throwing motion and may be beneficial for throwers during their prethrowing warm-up routine. PMID:15902319

  2. Mechanical correction of dynamometer moment for the effects of segment motion during isometric knee-extension tests

    PubMed Central

    Baltzopoulos, Vasilios; Richards, Paula J.; Maganaris, Constantinos N.

    2011-01-01

    The purpose of this study was to determine the effect of dynamometer and joint axis misalignment on measured isometric knee-extension moments using inverse dynamics based on the actual joint kinematic information derived from the real-time X-ray video and to compare the errors when the moments were calculated using measurements from external anatomical surface markers or obtained from the isokinetic dynamometer. Six healthy males participated in this study. They performed isometric contractions at 90° and 20° of knee flexion, gradually increasing to maximum effort. For the calculation of the actual knee-joint moment and the joint moment relative to the knee-joint center, determined using the external marker, two free body diagrams were used of the Cybex arm and the lower leg segment system. In the first free body diagram, the mean center of the circular profiles of the femoral epicondyles was used as the knee-joint center, whereas in the second diagram, the joint center was assumed to coincide with the external marker. Then, the calculated knee-joint moments were compared with those measured by the dynamometer. The results indicate that 1) the actual knee-joint moment was different from the dynamometer recorded moment (difference ranged between 1.9% and 4.3%) and the moment calculated using the skin marker (difference ranged between 2.5% and 3%), and 2) during isometric knee extension, the internal knee angle changed significantly from rest to the maximum contraction state by about 19°. Therefore, these differences cannot be neglected if the moment–knee-joint angle relationship or the muscle mechanical properties, such as length-tension relationship, need to be determined. PMID:21474701

  3. Periodization effects during short-term resistance training with equated exercise variables in females.

    PubMed

    Pelzer, Thiemo; Ullrich, Boris; Pfeiffer, Mark

    2017-03-01

    During resistance training, volume and load can be altered either gradually (traditional periodization: TP) or with frequent changes between subsequent sessions (daily undulating periodization: DUP). We hypothesized that the periodization model employed would not impact upon training-induced adaptations when exercise variables are equated. Nineteen females (22.0 years, moderate resistance training experience of 27.9 months) performed 6 weeks of knee extensor training with 3 weekly sessions exercising one leg using TP and the contralateral leg using DUP. Training load varied between 40, 60, and 80% of one repetition maximum (1RM). Volume, range of motion, and time under tension were equated for each leg with a biofeedback software. Dynamometry, surface EMG and ultrasonography were used to determine temporal changes of knee extensor maximum voluntary strength (MVC), neural drive of the M. quadriceps femoris (QF) and vastus lateralis (VL) and rectus femoris (RF) muscle architecture. Significant (P < 0.05) gains for isometric (TP 15%, DUP 13%) and isokinetic-concentric (TP 8%, DUP 10%) MVC and knee extensor 1RM (TP 18%, DUP 24%) occurred post training. VL and RF-muscle thickness showed significant (P < 0.05) increases ranging from 12 to 20% for TP and from 13 to 19% for DUP. Furthermore, significant (P < 0.05) increases in VL-pennation angle and VL-fascicle length occurred in both legs while QF EMG remained unchanged. No significant temporal differences were found between both models, displaying similar small to large effect sizes. Periodization is no adaptation trigger during short-term resistance training with equated exercise variables.

  4. Dosages of cold-water immersion post exercise on functional and clinical responses: a randomized controlled trial.

    PubMed

    Machado, A F; Almeida, A C; Micheletti, J K; Vanderlei, F M; Tribst, M F; Netto Junior, J; Pastre, C M

    2017-11-01

    Cold-water immersion (CWI) is one of the recovery techniques commonly used by athletes for post-exercise recovery. Nevertheless, the effects of CWI using different temperatures and the dose-response relationship of this technique have not yet been investigated. The aims of this study were to compare the effects of two strategies of CWI, using different water temperatures with passive recovery post exercise in the management of some markers of muscle damage, and to observe whether any of the techniques used caused deleterious effects on performance. Sixty healthy male participants performed an eccentric protocol to induce muscle damage and were then randomized to one of three groups (CWI1: 15 min at 9 °C; CWI2: 15 min at 14 °C; CG: control group). Levels of creatine kinase, muscle soreness, pain threshold, perception of recovery, and maximal voluntary isometric contraction were monitored up to 96 h post exercise. A large effect for time for all outcomes was observed [P < 0.001; CK (ES = 0.516), muscle soreness (ES = 0.368); pain threshold (ES = 0.184); perception of recovery (ES = 0.565); MVIC (ES = 0.273)]. CWI groups presented an earlier recovery for muscle soreness with lower ratings immediately post recovery. For delayed effects, the application of CWI2 (15 min at 14 °C) presented earlier recovery compared with CWI1 and control condition for maximal voluntary isometric contraction (P < 0.05). There were no significant group and interaction (Group × Time) effects. CWI groups acted more efficiently for muscle soreness and performance considering the time of recovery was observed. No evidence was found to suggest dose-response relationship and deleterious effects. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  5. Influence of exercise induced hyperlactatemia on retinal blood flow during normo- and hyperglycemia.

    PubMed

    Garhöfer, Gerhard; Kopf, Andreas; Polska, Elzbieta; Malec, Magdalena; Dorner, Guido T; Wolzt, Michael; Schmetterer, Leopold

    2004-05-01

    Short term hyperglycemia has previously been shown to induce a blood flow increase in the retina. The mechanism behind this effect is poorly understood. We set out to investigate whether exercise-induced hyperlactatemia may alter the response of retinal blood flow to hyperglycemia. We performed a randomized, controlled two-way cross over study comprising 12 healthy subjects, performed a 6-minutes period of dynamic exercise during an euglcaemic or hyperglycaemic insulin clamp. Retinal blood flow was assessed by combined vessel size measurement with the Zeiss retinal vessel analyzer and measurement of red blood cell velocities using bi-directional laser Doppler velocimetry. Retinal and systemic hemodynamic parameters were measured before, immediately after and 10 and 20 minutes after isometric exercise. On the euglycemic study day retinal blood flow increased after dynamic exercise. The maximum increase in retinal blood flow was observed 10 minutes after the end of exercise when lactate plasma concentration peaked. Hyperglycemia increased retinal blood flow under basal conditions, but had no incremental effect during exercise induced hyperlactatemia. Our results indicate that both lactate and glucose induce an increase in retinal blood flow in healthy humans. This may indicate a common pathway between glucose and lactate induced blood flow changes in the human retina.

  6. Electromyographical Comparison of Four Common Shoulder Exercises in Unstable and Stable Shoulders

    PubMed Central

    Sciascia, Aaron; Kuschinsky, Nina; Nitz, Arthur J.; Mair, Scott D.; Uhl, Tim L.

    2012-01-01

    This study examines if electromyographic (EMG) amplitude differences exist between patients with shoulder instability and healthy controls performing scaption, prone horizontal abduction, prone external rotation, and push-up plus shoulder rehabilitation exercises. Thirty nine subjects were categorized by a single orthopedic surgeon as having multidirectional instability (n = 10), anterior instability (n = 9), generalized laxity (n = 10), or a healthy shoulder (n = 10). Indwelling and surface electrodes were utilized to measure EMG activity (reported as a % of maximum voluntary isometric contraction (MVIC)) in various shoulder muscles during 4 common shoulder exercises. The exercises studied effectively activated the primary musculature targeted in each exercise equally among all groups. The serratus anterior generated high activity (50–80% MVIC) during a push-up plus, while the infraspinatus and teres major generated moderate-to-high activity (30–80% MVIC) during both the prone horizontal and prone external rotation exercises. Scaption exercise generated moderate activity (20–50% MVIC) in both rotator cuff and scapular musculature. Clinicians should feel confident in prescribing these shoulder-strengthening exercises in patients with shoulder instability as the activation levels are comparable to previous findings regarding EMG amplitudes and should improve the dynamic stabilization capability of both rotator cuff and scapular muscles using exercises designed to address glenohumeral joint instability. PMID:22919499

  7. Efflux of creatine kinase from isolated soleus muscle depends on age, sex and type of exercise in mice.

    PubMed

    Baltusnikas, Juozas; Venckunas, Tomas; Kilikevicius, Audrius; Fokin, Andrej; Ratkevicius, Aivaras

    2015-06-01

    Elevated plasma creatine kinase (CK) activity is often used as an indicator of exercise-induced muscle damage. Our aim was to study effects of contraction type, sex and age on CK efflux from isolated skeletal muscles of mice. The soleus muscle (SOL) of adult (7.5-month old) female C57BL/6J mice was subjected to either 100 passive stretches, isometric contractions or eccentric contractions, and muscle CK efflux was assessed after two-hour incubation in vitro. SOL of young (3-month old) male and female mice was studied after 100 eccentric contractions. For adult females, muscle CK efflux was larger (p < 0.05) after eccentric contractions than after incubation without exercise (698 ± 344 vs. 268 ± 184 mU·h(-1), respectively), but smaller (p < 0.05) than for young females after the same type of exercise (1069 ± 341 mU·h(-1)). Eccentric exercise-induced CK efflux was larger in muscles of young males compared to young females (2046 ± 317 vs 1069 ± 341 mU · h(-1), respectively, p < 0.001). Our results show that eccentric contractions induce a significant increase in muscle CK efflux immediately after exercise. Isolated muscle resistance to exercise-induced CK efflux depends on age and sex of mice. Key pointsMuscle lengthening contractions induce the highest CK efflux in vitro compared with similar protocol of isometric contractions or passive stretches.Muscle CK efflux in vitro is applicable in studying changes of sarcolemma permeability/integrity, a proxy of muscle damage, in response to muscle contractile activity.Isolated muscle resistance to exercise-induced CK efflux is greater in female compared to male mice of young age and is further increased in adult female mice.

  8. Efflux of Creatine Kinase from Isolated Soleus Muscle Depends on Age, Sex and Type of Exercise in Mice

    PubMed Central

    Baltusnikas, Juozas; Venckunas, Tomas; Kilikevicius, Audrius; Fokin, Andrej; Ratkevicius, Aivaras

    2015-01-01

    Elevated plasma creatine kinase (CK) activity is often used as an indicator of exercise-induced muscle damage. Our aim was to study effects of contraction type, sex and age on CK efflux from isolated skeletal muscles of mice. The soleus muscle (SOL) of adult (7.5-month old) female C57BL/6J mice was subjected to either 100 passive stretches, isometric contractions or eccentric contractions, and muscle CK efflux was assessed after two-hour incubation in vitro. SOL of young (3-month old) male and female mice was studied after 100 eccentric contractions. For adult females, muscle CK efflux was larger (p < 0.05) after eccentric contractions than after incubation without exercise (698 ± 344 vs. 268 ± 184 mU·h−1, respectively), but smaller (p < 0.05) than for young females after the same type of exercise (1069 ± 341 mU·h−1). Eccentric exercise-induced CK efflux was larger in muscles of young males compared to young females (2046 ± 317 vs 1069 ± 341 mU · h−1, respectively, p < 0.001). Our results show that eccentric contractions induce a significant increase in muscle CK efflux immediately after exercise. Isolated muscle resistance to exercise-induced CK efflux depends on age and sex of mice. Key points Muscle lengthening contractions induce the highest CK efflux in vitro compared with similar protocol of isometric contractions or passive stretches. Muscle CK efflux in vitro is applicable in studying changes of sarcolemma permeability/integrity, a proxy of muscle damage, in response to muscle contractile activity. Isolated muscle resistance to exercise-induced CK efflux is greater in female compared to male mice of young age and is further increased in adult female mice. PMID:25983588

  9. Effects of one-night sleep deprivation on selective attention and isometric force in adolescent karate athletes.

    PubMed

    Ben Cheikh, Ridha; Latiri, Imed; Dogui, Mohamed; Ben Saad, Helmi

    2017-06-01

    Most of the available literature related to aspects of sleep deprivation is primarily focused on memory and learning, and studies regarding its effects on selective attention and/or physical performance are scarce. Moreover, the available literature includes general population or people involved in team sports (e.g. volleyball). However, only few studies were performed on athletes involved in combat sports (e.g. karate). The aim of the present study was to determine the effects of a total one-night sleep deprivation (1NSD) on activation and inhibition processes of selective attention and on maximal isometric force in karate athletes. Twelve young karate athletes (mean age 16.9±0.8 years) were enrolled. The protocol consists of two successive sessions: a normal night's sleep (NNS) and a total 1NSD. After each night, athletes performed selective attention and muscle strength tests during the same following three times (T) of the day: T1NNS or T11NSD: 8-9 a.m.; T2NNS or T21NSD: 12 a.m.-1 p.m.; T3NNS or T31NSD: 4-5 p.m. Activation (simple [SRT] and choice reaction times [CRT]) and inhibition (negative priming) processes were evaluated using Superlab v. 4.5 software (Cedrus Corporation, San Pedro, CA, USA). Maximal force and maximal force time (MFT) of brachial biceps isometric contraction were evaluated (Ergo System®, Globus, Codognè, Italy). A non-parametric test was used to evaluate the sessions (NNS vs. SND for the same time period) and time (T1NNS vs. 1NSD) effects. All athletes completed all tests after a NNS. Twelve, eleven and four athletes completed all tests at T11NSD, T21NSD and T31NSD, respectively. As for sessions effects, no statistically significant difference was found. As for time effects, a significant increase in SRT at T21NSD vs. T1NNS (345±47 vs. 317±33 ms, respectively), a significant increase in MFT at T21NSD vs. T1NNS (2172±260 vs.1885±292 ms, respectively), and no significant changes in CRT and negative priming reaction time or MFT data

  10. Brain mechanisms that underlie the effects of motivational audiovisual stimuli on psychophysiological responses during exercise.

    PubMed

    Bigliassi, Marcelo; Silva, Vinícius B; Karageorghis, Costas I; Bird, Jonathan M; Santos, Priscila C; Altimari, Leandro R

    2016-05-01

    Motivational audiovisual stimuli such as music and video have been widely used in the realm of exercise and sport as a means by which to increase situational motivation and enhance performance. The present study addressed the mechanisms that underlie the effects of motivational stimuli on psychophysiological responses and exercise performance. Twenty-two participants completed fatiguing isometric handgrip-squeezing tasks under two experimental conditions (motivational audiovisual condition and neutral audiovisual condition) and a control condition. Electrical activity in the brain and working muscles was analyzed by use of electroencephalography and electromyography, respectively. Participants were asked to squeeze the dynamometer maximally for 30s. A single-item motivation scale was administered after each squeeze. Results indicated that task performance and situational motivational were superior under the influence of motivational stimuli when compared to the other two conditions (~20% and ~25%, respectively). The motivational stimulus downregulated the predominance of low-frequency waves (theta) in the right frontal regions of the cortex (F8), and upregulated high-frequency waves (beta) in the central areas (C3 and C4). It is suggested that motivational sensory cues serve to readjust electrical activity in the brain; a mechanism by which the detrimental effects of fatigue on the efferent control of working muscles is ameliorated. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. Recovery From Exercise-Induced Muscle Damage: Cold-Water Immersion Versus Whole-Body Cryotherapy.

    PubMed

    Abaïdia, Abd-Elbasset; Lamblin, Julien; Delecroix, Barthélémy; Leduc, Cédric; McCall, Alan; Nédélec, Mathieu; Dawson, Brian; Baquet, Georges; Dupont, Grégory

    2017-03-01

    To compare the effects of cold-water immersion (CWI) and whole-body cryotherapy (WBC) on recovery kinetics after exercise-induced muscle damage. Ten physically active men performed single-leg hamstring eccentric exercise comprising 5 sets of 15 repetitions. Immediately postexercise, subjects were exposed in a randomized crossover design to CWI (10 min at 10°C) or WBC (3 min at -110°C) recovery. Creatine kinase concentrations, knee-flexor eccentric (60°/s) and posterior lower-limb isometric (60°) strength, single-leg and 2-leg countermovement jumps, muscle soreness, and perception of recovery were measured. The tests were performed before and immediately, 24, 48, and 72 h after exercise. Results showed a very likely moderate effect in favor of CWI for single-leg (effect size [ES] = 0.63; 90% confidence interval [CI] = -0.13 to 1.38) and 2-leg countermovement jump (ES = 0.68; 90% CI = -0.08 to 1.43) 72 h after exercise. Soreness was moderately lower 48 h after exercise after CWI (ES = -0.68; 90% CI = -1.44 to 0.07). Perception of recovery was moderately enhanced 24 h after exercise for CWI (ES = -0.62; 90% CI = -1.38 to 0.13). Trivial and small effects of condition were found for the other outcomes. CWI was more effective than WBC in accelerating recovery kinetics for countermovement-jump performance at 72 h postexercise. CWI also demonstrated lower soreness and higher perceived recovery levels across 24-48 h postexercise.

  12. The use of abdominal muscle training, breathing exercises and abdominal massage to treat paediatric chronic functional constipation.

    PubMed

    Silva, C A G; Motta, M E F A

    2013-05-01

    The effect of muscular training, abdominal massage and diaphragmatic breathing was compared with medical treatment in a prospective randomized trial of patients with chronic functional constipation. Patients aged 4-18 years old with functional constipation according to the Rome III criteria were randomized to physiotherapy or medical treatment. In the physiotherapy group, exercises (isometric training of the abdominal muscles, diaphragmatic breathing exercises and abdominal massage) were employed during 12 40-min sessions twice a week by a trained physiotherapist, with laxatives. Patients in the medication group were only given laxatives. Primary outcome measures were frequency of defaecation and faecal incontinence. The analysis was performed by intention-to-treat. After 6 weeks of treatment, the frequency of bowel movements was higher in the physiotherapy group [5.1 (2.1) days/week] than in the medication group [3.9 (2.0) days/week] (P = 0.01). The frequency of faecal incontinence was no different between the groups [3.6 (1.9) days/week vs 3.0 (2.1) days/week] (P = 0.31). The combined use of isometric training of abdominal muscles, breathing exercises and abdominal massage increased defaecation frequency after 6 weeks but faecal incontinence remained unchanged. Physiotherapy may be a useful treatment for constipation. Colorectal Disease © 2013 The Association of Coloproctology of Great Britain and Ireland.

  13. Effect of morphine on sympathetic nerve activity in humans

    NASA Technical Reports Server (NTRS)

    Carter, Jason R.; Sauder, Charity L.; Ray, Chester A.

    2002-01-01

    There are conflicting reports for the role of endogenous opioids on sympathetic and cardiovascular responses to exercise in humans. A number of studies have utilized naloxone (an opioid-receptor antagonist) to investigate the effect of opioids during exercise. In the present study, we examined the effect of morphine (an opioid-receptor agonist) on sympathetic and cardiovascular responses at rest and during isometric handgrip (IHG). Eleven subjects performed 2 min of IHG (30% maximum) followed by 2 min of postexercise muscle ischemia (PEMI) before and after systemic infusion of morphine (0.075 mg/kg loading dose + 1 mg/h maintenance) or placebo (saline) in double-blinded experiments on separate days. Morphine increased resting muscle sympathetic nerve activity (MSNA; 17 +/- 2 to 22 +/- 2 bursts/min; P < 0.01) and increased mean arterial pressure (MAP; 87 +/- 2 to 91 +/- 2 mmHg; P < 0.02), but it decreased heart rate (HR; 61 +/- 4 to 59 +/- 3; P < 0.01). However, IHG elicited similar increases for MSNA, MAP, and HR between the control and morphine trial (drug x exercise interaction = not significant). Moreover, responses to PEMI were not different. Placebo had no effect on resting, IHG, and PEMI responses. We conclude that morphine modulates cardiovascular and sympathetic responses at rest but not during isometric exercise.

  14. Does the Length of Elbow Flexors and Visual Feedback Have Effect on Accuracy of Isometric Muscle Contraction in Men after Stroke?

    PubMed Central

    Juodzbaliene, Vilma; Darbutas, Tomas; Skurvydas, Albertas

    2016-01-01

    The aim of the study was to determine the effect of different muscle length and visual feedback information (VFI) on accuracy of isometric contraction of elbow flexors in men after an ischemic stroke (IS). Materials and Methods. Maximum voluntary muscle contraction force (MVMCF) and accurate determinate muscle force (20% of MVMCF) developed during an isometric contraction of elbow flexors in 90° and 60° of elbow flexion were measured by an isokinetic dynamometer in healthy subjects (MH, n = 20) and subjects after an IS during their postrehabilitation period (MS, n = 20). Results. In order to evaluate the accuracy of the isometric contraction of the elbow flexors absolute errors were calculated. The absolute errors provided information about the difference between determinate and achieved muscle force. Conclusions. There is a tendency that greater absolute errors generating determinate force are made by MH and MS subjects in case of a greater elbow flexors length despite presence of VFI. Absolute errors also increase in both groups in case of a greater elbow flexors length without VFI. MS subjects make greater absolute errors generating determinate force without VFI in comparison with MH in shorter elbow flexors length. PMID:27042670

  15. Isometric elbow extensors strength in supine- and prone-lying positions.

    PubMed

    Abdelzaher, Ibrahim E; Ababneh, Anas F; Alzyoud, Jehad M

    2013-01-01

    The purpose of this study was to compare isometric strength of elbow extensors measured in supine- and prone-lying positions at elbow flexion angles of 45 and 90 degrees. Twenty-two male subjects under single-blind procedures participated in the study. Each subject participated in both supine-lying and prone-lying measuring protocols. Calibrated cable tensiometer was used to measure isometric strength of the right elbow extensors and a biofeedback electromyography was used to assure no substitution movements from shoulder girdle muscles. The mean values of isometric strength of elbow extensors measured from supine-lying position at elbow flexion angles of 45 and 90 degrees were 11.1  ±  4.2 kg and 13.1  ±  4.6 kg, while those measured from prone-lying position were 9.9  ±  3.6 kg and 12  ±  4.2 kg, respectively. There is statistical significant difference between the isometric strength of elbow extensors measured from supine-lying position at elbow flexion angles of 45 and 90 degrees compared to that measured from prone-lying position (p  <  0.05). The results suggest that in manual muscle testing starting position can affect the isometric strength of elbow extensors since supine-lying starting position is better than prone-lying starting position.

  16. Influences of Fascicle Length During Isometric Training on Improvement of Muscle Strength.

    PubMed

    Tanaka, Hiroki; Ikezoe, Tome; Umehara, Jun; Nakamura, Masatoshi; Umegaki, Hiroki; Kobayashi, Takuya; Nishishita, Satoru; Fujita, Kosuke; Araki, Kojiro; Ichihashi, Noriaki

    2016-11-01

    Tanaka, H, Ikezoe, T, Umehara, J, Nakamura, M, Umegaki, H, Kobayashi, T, Nishishita, S, Fujita, K, Araki, K, and Ichihashi, N. Influences of fascicle length during isometric training on improvement of muscle strength. J Strength Cond Res 30(11): 3249-3255, 2016-This study investigated whether low-intensity isometric training would elicit a greater improvement in maximum voluntary contraction (MVC) at the same fascicle length, rather than the joint angle, adopted during training. Sixteen healthy women (21.8 ± 1.5 years) were randomly divided into an intervention group and a control group. Before (Pre) and after (Post) training, isometric plantarflexion MVCs were measured every 10° through the range of ankle joint position from 20° dorsiflexion to 30° plantarflexion (i.e., 6 ankle angles). Medial gastrocnemius fascicle length was also measured at each position, using B-mode ultrasound under 3 conditions of muscle activation: at rest, 30%MVC at respective angles, and MVC. Plantarflexion resistance training at an angle of 20° plantarflexion was performed 3 days a week for 4 weeks at 30%MVC using 3 sets of twenty 3-second isometric contractions. Maximum voluntary contraction in the intervention group increased at 0 and 10° plantarflexion (0°; Pre: 81.2 ± 26.5 N·m, Post: 105.0 ± 21.6 N·m, 10°; Pre: 63.0 ± 23.6 N·m, Post: 81.3 ± 20.3 N·m), which was not the angle used in training (20°). However, the fascicle length adopted in training at 20° plantarflexion and 30%MVC was similar to the value at 0 or 10° plantarflexion at MVC. Low-intensity isometric training at a shortened muscle length may be effective for improving MVC at a lengthened muscle length because of specificity of the fascicle length than the joint angle.

  17. Portfolio theory of optimal isometric force production: Variability predictions and nonequilibrium fluctuation dissipation theorem

    NASA Astrophysics Data System (ADS)

    Frank, T. D.; Patanarapeelert, K.; Beek, P. J.

    2008-05-01

    We derive a fundamental relationship between the mean and the variability of isometric force. The relationship arises from an optimal collection of active motor units such that the force variability assumes a minimum (optimal isometric force). The relationship is shown to be independent of the explicit motor unit properties and of the dynamical features of isometric force production. A constant coefficient of variation in the asymptotic regime and a nonequilibrium fluctuation-dissipation theorem for optimal isometric force are predicted.

  18. Core Muscle Activation in Suspension Training Exercises.

    PubMed

    Cugliari, Giovanni; Boccia, Gennaro

    2017-02-01

    A quantitative observational laboratory study was conducted to characterize and classify core training exercises executed in a suspension modality on the base of muscle activation. In a prospective single-group repeated measures design, seventeen active male participants performed four suspension exercises typically associated with core training (roll-out, bodysaw, pike and knee-tuck). Surface electromyographic signals were recorded from lower and upper parts of rectus abdominis, external oblique, internal oblique, lower and upper parts of erector spinae muscles using concentric bipolar electrodes. The average rectified values of electromyographic signals were normalized with respect to individual maximum voluntary isometric contraction of each muscle. Roll-out exercise showed the highest activation of rectus abdominis and oblique muscles compared to the other exercises. The rectus abdominis and external oblique reached an activation higher than 60% of the maximal voluntary contraction (or very close to that threshold, 55%) in roll-out and bodysaw exercises. Findings from this study allow the selection of suspension core training exercises on the basis of quantitative information about the activation of muscles of interest. Roll-out and bodysaw exercises can be considered as suitable for strength training of rectus abdominis and external oblique muscles.

  19. Age and Sex Effects on the Active Stiffness of Vastus Intermedius under Isometric Contraction

    PubMed Central

    Wang, Cong-Zhi; Guo, Jing-Yi; Li, Tian-Jie; Shi, Wenxiu; Zheng, Yong-Ping

    2017-01-01

    Previously, a novel technique was proposed to quantify the relationship between the muscle stiffness and its nonfatigue contraction intensity. The method extended the measured range of isometric contraction to 100% maximum voluntary contraction (MVC) using an ultrasonic shear wave measurement setup. Yet, it has not been revealed how this relationship could be affected by factors like age or sex. To clarify these questions, vastus intermedius (VI) stiffness of 40 healthy subjects was assessed under 11 step levels of isometric contraction. The subjects were divided into four groups: young males, young females, elderly males, and elderly females (n = 10 for each). In a relaxed state, no significant difference was observed between the male and female subjects (p = 0.156) nor between the young and elderly subjects (p = 0.221). However, when performing isometric contraction, the VI stiffness of males was found to be significantly higher than that of females at the same level (p < 0.001), and that of the young was higher than the elderly (p < 0.001). Meanwhile, for two knee joint angles used, the stiffness measured at a 90° knee joint angle was always significantly larger than that measured at 60° (p < 0.001). Recognizing the active muscle stiffness of VI contributes to body stability, and these results may provide insight into the age and sex bias in musculoskeletal studies, such as those on fall risks. PMID:28473990

  20. Effect of functional isometric squats on vertical jump in trained and untrained men.

    PubMed

    Berning, Joseph M; Adams, Kent J; DeBeliso, Mark; Sevene-Adams, Patricia G; Harris, Chad; Stamford, Bryant A

    2010-09-01

    Functional isometrics (FIs) combine dynamic and isometric muscle actions and may hyperstimulate the nervous system leading to an enhanced postactivation potentiation (PAP) and improved subsequent performance. The purpose of this study was to investigate the impact of an FI squat on the countermovement vertical jump (CMVJ) in resistance trained and untrained men. Thirteen trained men (age: 22.8 +/- 3.2 years, mass: 90.0 +/- 16.3 kg, and height: 178.9 +/- 7.1 cm) and 8 untrained men (age: 28.5 +/- 5.9 years, mass: 101.5 +/- 23.0 kg, and height: 177.0 +/- 4.8 cm) participated. On separate days, subjects performed CMVJs after 2 different warm-up conditions. The warm-up conditions consisted of either 5 minutes of low-intensity cycling or 5 minutes of low-intensity cycling plus a 3-second FI squat with 150% of their 1 repetition maximum (1RM). A 2 x 3 repeated-measures analysis of variance with Bonferroni post hoc revealed that when comparing the 2 warm-up conditions in the trained subjects, a significant increase (p < 0.05) in CMVJ occurred at 4 minutes (2.4 cm, +5.1%) post-FI squat. This increase was maintained when subjects were retested at 5 minutes post (2.6 cm, + 5.5%). No significant difference in CMVJ was detected in the untrained group (p = 0.49). Results support the addition of an FI squat performed at 150% of 1RM to a low-intensity cycling warm-up to enhance PAP in resistance trained but not in untrained men as measured by CMVJ. Practically, adding functional isometrics to a warm-up scheme may significantly enhance acute, short-term power output in resistance trained men.

  1. Gluteus Minimus and Gluteus Medius Muscle Activity During Common Rehabilitation Exercises in Healthy Postmenopausal Women.

    PubMed

    Ganderton, Charlotte; Pizzari, Tania; Cook, Jill; Semciw, Adam

    2017-12-01

    Study Design Controlled laboratory study, cross-sectional. Background The gluteus medius (GMed) and gluteus minimus (GMin) provide dynamic stability of the hip joint and pelvis. These muscles are susceptible to atrophy and injury in individuals during menopause, aging, and disease. Numerous studies have reported on the ability of exercises to elicit high levels of GMed activity; however, few studies have differentiated between the portions of the GMed, and none have examined the GMin. Objectives To quantify and rank the level of muscle activity of the 2 segments of the GMin (anterior and posterior fibers) and 3 segments of the GMed (anterior, middle, and posterior fibers) during 4 isometric and 3 dynamic exercises in a group of healthy, postmenopausal women. Methods Intramuscular electrodes were inserted into each segment of the GMed and GMin in 10 healthy, postmenopausal women. Participants completed 7 gluteal rehabilitation exercises, and average normalized muscle activity was used to rank the exercises from highest to lowest. Results The isometric standing hip hitch with contralateral hip swing was the highest-ranked exercise for all muscle segments except the anterior GMin, where it was ranked second. The highest-ranked dynamic exercise for all muscle segments was the dip test. Conclusion The hip hitch and its variations maximally activate the GMed and GMin muscle segments, and may be useful in hip muscle rehabilitation in postmenopausal women. J Orthop Sports Phys Ther 2017;47(12):914-922. Epub 15 Oct 2017. doi:10.2519/jospt.2017.7229.

  2. 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.

  3. Age-associated changes in muscle activity during isometric contraction.

    PubMed

    Arjunan, Sridhar P; Kumar, Dinesh K

    2013-04-01

    We investigated the effect of age on the complexity of muscle activity and the variance in the force of isometric contraction. Surface electromyography (sEMG) from biceps brachii muscle and force of contraction were recorded from 96 subjects (20-70 years of age) during isometric contractions. There was a reduction in the complexity of sEMG associated with aging. The relationship of age and complexity was approximated using a bilinear fit, with the average knee point at 45 years. There was an age-associated increase in the coefficient of variation (CoV) of the force of muscle contraction, and this increase was correlated with the decrease in complexity of sEMG (r(2) = 0.76). There was an age-associated increase in CoV and also a reduction in the complexity of sEMG. The correlation between these 2 factors can be explained based on the age-associated increase in motor unit density. Copyright © 2012 Wiley Periodicals, Inc.

  4. The effect of intermittent lower limb occlusion on recovery following exercise-induced muscle damage: A randomized controlled trial.

    PubMed

    Page, Will; Swan, Rachael; Patterson, Stephen D

    2017-08-01

    The purpose of this investigation was to examine the effectiveness of intermittent lower limb occlusion in augmenting recovery from exercise induced muscle damage (EIMD) in physically active males. Randomized controlled trial, double blind. Sixteen healthy recreationally active male participants were randomly assigned to an intermittent occlusion (OCC; n=8) or control (SHAM; n=8) group. The EIMD protocol comprised of 100 drop-jumps, from a 0.6m box. Indices of muscle damage were creatine kinase (CK), thigh-circumference (TC), muscle soreness (DOMS), counter-movement jump (CMJ) and maximal isometric voluntary contraction (MIVC). Measurements were assessed pre, 24h, 48h and 72h following exercise. There was a significant time effect for all indices of muscle damage suggesting EIMD was present following the exercise protocol. The decrease in MIVC was significantly attenuated in the OCC group compared to the SHAM group at 24 (90.4±10.7 vs. 81.5±6.7%), 48 (96.2±6.1 vs. 84.5±7.1%) and 72h (101.1±4.2 vs. 89.7±7.5%). The CK response was reduced in the OCC group at 24 (335±87 vs. 636±300 IU) and 48h (244±70 vs. 393±248 IU), compared to the SHAM group. DOMS was significantly lower in the OCC compared to the SHAM group at 24, 48 and 72h post EIMD. There was no effect of OCC on CMJ or TC. This investigation shows that intermittent lower limb occlusion administered after a damaging bout of exercise reduces indices of muscle damage and accelerates the recovery in physically active males. Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  5. Effect of inorganic phosphate on the force and number of myosin cross-bridges during the isometric contraction of permeabilized muscle fibers from rabbit psoas.

    PubMed

    Caremani, Marco; Dantzig, Jody; Goldman, Yale E; Lombardi, Vincenzo; Linari, Marco

    2008-12-15

    The relation between the chemical and mechanical steps of the myosin-actin ATPase reaction that leads to generation of isometric force in fast skeletal muscle was investigated in demembranated fibers of rabbit psoas muscle by determining the effect of the concentration of inorganic phosphate (Pi) on the stiffness of the half-sarcomere (hs) during transient and steady-state conditions of the isometric contraction (temperature 12 degrees C, sarcomere length 2.5 mum). Changes in the hs strain were measured by imposing length steps or small 4 kHz oscillations on the fibers in control solution (without added Pi) and in solution with 3-20 mM added Pi. At the plateau of the isometric contraction in control solution, the hs stiffness is 22.8 +/- 1.1 kPa nm(-1). Taking the filament compliance into account, the total stiffness of the array of myosin cross-bridges in the hs (e) is 40.7 +/- 3.7 kPa nm(-1). An increase in [Pi] decreases the stiffness of the cross-bridge array in proportion to the isometric force, indicating that the force of the cross-bridge remains constant independently of [Pi]. The rate constant of isometric force development after a period of unloaded shortening (r(F)) is 23.5 +/- 1.0 s(-1) in control solution and increases monotonically with [Pi], attaining a maximum value of 48.6 +/- 0.9 s(-1) at 20 mM [Pi], in agreement with the idea that Pi release is a relatively fast step after force generation by the myosin cross-bridge. During isometric force development at any [Pi], e and thus the number of attached cross-bridges increase in proportion to the force, indicating that, independently of the speed of the process that leads to myosin attachment to actin, there is no significant (>1 ms) delay between generation of stiffness and generation of force by the cross-bridges.

  6. Attenuation of muscle damage by preconditioning with muscle hyperthermia 1-day prior to eccentric exercise.

    PubMed

    Nosaka, K; Muthalib, M; Lavender, A; Laursen, P B

    2007-01-01

    This study investigated the hypothesis that muscle damage would be attenuated in muscles subjected to passive hyperthermia 1 day prior to exercise. Fifteen male students performed 24 maximal eccentric actions of the elbow flexors with one arm; the opposite arm performed the same exercise 2-4 weeks later. The elbow flexors of one arm received a microwave diathermy treatment that increased muscle temperature to over 40 degrees C, 16-20 h prior to the exercise. The contralateral arm acted as an untreated control. Maximal voluntary isometric contraction strength (MVC), range of motion (ROM), upper arm circumference, muscle soreness, plasma creatine kinase activity and myoglobin concentration were measured 1 day prior to exercise, immediately before and after exercise, and daily for 4 days following exercise. Changes in the criterion measures were compared between conditions (treatment vs. control) using a two-way repeated measures ANOVA with a significance level of P < 0.05. All measures changed significantly following exercise, but the treatment arm showed a significantly faster recovery of MVC, a smaller change in ROM, and less muscle soreness compared with the control arm. However, the protective effect conferred by the diathermy treatment was significantly less effective compared with that seen in the second bout performed 4-6 weeks after the initial bout by a subgroup of the subjects (n = 11) using the control arm. These results suggest that passive hyperthermia treatment 1 day prior to eccentric exercise-induced muscle damage has a prophylactic effect, but the effect is not as strong as the repeated bout effect.

  7. Experimental effects of acute exercise duration and exercise recovery on mood state.

    PubMed

    Crush, Elizabeth A; Frith, Emily; Loprinzi, Paul D

    2018-03-15

    Accumulating evidence suggests that, in addition to various psychosocial parameters, affective responses to exercise play an important role in subserving future exercise behavior. This study comprehensively evaluated whether acute exercise duration and recovery period influenced the relationship between moderate-intensity walking exercise and mood profile. We employed a randomized controlled cross-over trial. Participants completed two laboratory visits, separated by one-week. One of the visits involved a mood profile assessment with no exercise, while the other visit involved a mood profile assessment after an acute bout of exercise. Participants (N = 352; 22 per group; young [M age = 21 yrs] healthy adults) were randomized into one of 16 experimental groups: 10, 20, 30, 45 or 60min bout of exercise coupled with either a 5, 15 or 30min recovery period. The exercise bout was of moderate-intensity (40-59% of HRR). Mood profile was assessed from the POMS survey, considering subscales of depression, anger and hostility. For all three mood profile parameters, there was no evidence of a group x time interaction effect. However, the main effect for time was statistically significant for each mood parameter. These significant results demonstrate that, generally, exercise had a favorable effect on each of the mood profile, regardless of exercise duration and recovery period. In addition to the significant main effects for time, we also observed a significant main effect for group for the mood parameter hostility. With the exception of the group 13 (60min of exercise with 5min recovery) and the 3 groups that employed a 10-min bout of exercise (groups 1-3), all other experimental groups had a lower (better) hostility score after the exercise visit. Generally, exercise had a favorable effect on various mood profiles, regardless of exercise duration (between 10 and 60min) and recovery period (between 5 and 30min). Copyright © 2018 Elsevier B.V. All rights reserved.

  8. 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.

  9. Assessing Muscle-Strength Asymmetry via a Unilateral-Stance Isometric Midthigh Pull.

    PubMed

    Dos'Santos, Thomas; Thomas, Christopher; Jones, Paul A; Comfort, Paul

    2017-04-01

    To investigate the within-session reliability of bilateral- and unilateral-stance isometric midthigh-pull (IMTP) force-time characteristics including peak force (PF), relative PF, and impulse at time bands (0-100, 0-200, 0-250, and 0-300 milliseconds) and to compare isometric force-time characteristics between right and left and dominant (D) and nondominant (ND) limbs. Professional male rugby league and multisport male college athletes (N = 54; age, 23.4 ± 4.2 y; height, 1.80 ± 0.05 m; mass, 88.9 ± 12.9 kg) performed 3 bilateral IMTP trials and 6 unilateral-stance IMTP trials (3 per leg) on a force plate sampling at 600 Hz. Intraclass correlation coefficients (ICCs) and coefficients of variation (CVs) demonstrated high within-session reliability for bilateral and unilateral IMTP PF (ICC = .94, CV = 4.7-5.5%). Lower reliability measures and greater variability were observed for bilateral and unilateral IMTP impulse at time bands (ICC = .81-.88, CV = 7.7-11.8%). Paired-sample t tests and Cohen d effect sizes revealed no significant differences for all isometric force-time characteristics between right and left limbs in male college athletes (P >.05, d ≤ 0.32) and professional rugby league players (P > .05, d ≤ 0.11); however, significant differences were found between D and ND limbs in male college athletes (P < .001, d = 0.43-0.91) and professional rugby league players (P < .001, d = 0.27-0.46). This study demonstrated high within-session reliability for unilateral-stance IMTP PF, revealing significant differences in isometric force-time characteristics between D and ND limbs in male athletes.

  10. Feasibility of an inpatient exercise intervention for children undergoing hematopoietic stem cell transplant.

    PubMed

    Bogg, Tina Fung Ting; Broderick, Carolyn; Shaw, Peter; Cohn, Richard; Naumann, Fiona Leigh

    2015-12-01

    With improving survival rates following HSCT in children, QOL and management of short- and long-term effects need to be considered. Exercise may help mitigate fatigue and declines in fitness and strength. The aims of this study were to assess the feasibility of an inpatient exercise intervention for children undergoing HSCT and observe the changes in physical and psychological health. Fourteen patients were recruited, mean age 10 yr. A 6MWT, isometric upper and lower body strength, balance, fatigue, and QOL were assessed prior to Tx and six wk post-Tx. A supervised exercise program was offered five days per week during the inpatient period and feasibility assessed through uptake rate. The study had 100% program completion and 60% uptake rate of exercise sessions. The mean (± s.d.) weekly activity was 117.5 (± 79.3) minutes. Younger children performed significantly more minutes of exercise than adolescents. At reassessment, strength and fatigue were stabilized while aerobic fitness and balance decreased. QOL revealed a non-statistical trend towards improvement. No exercise-related adverse events were reported. A supervised inpatient exercise program is safe and feasible, with potential physiological and psychosocial benefits. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  11. Exercise therapy, patient education, and patellar taping in the treatment of adolescents with patellofemoral pain: a prospective pilot study with 6 months follow-up.

    PubMed

    Rathleff, Michael S; Rathleff, Camilla R; Holden, Sinead; Thorborg, Kristian; Olesen, Jens L

    2018-01-01

    Patellofemoral pain (PFP) is the most common knee condition among adolescents, with a prevalence of 6-7% resulting in reduced function and quality of life. Exercise therapy is recommended for treating PFP, but has only been tested in older adolescents (15-19 years). This pilot study aimed to investigate the adherence to, and clinical effects of, exercise and patient education in young adolescents (12-16 years), with PFP. Twenty adolescents (16 females) with PFP were recruited from a population-based cohort to undergo a 3-month multimodal intervention. This comprised of a 30-min patient education and group-based exercise therapy. Exercises included supervised lower extremity strength exercises three times per week, in addition to similar home-based strength exercises. Outcomes included a 7-point global rating of change scale (ranging from "completely recovered" to "worse than ever"), the Knee injury and Osteoarthritis Outcome Score (KOOS), physical activity scale (PAS), weekly sports participation and health-related quality of life measured by European Quality of Life 5 dimensions Youth (EQ-5DY) and isometric knee and hip muscle strength. Pain was measured on a visual analogue scale (VAS), and satisfaction treatment was measured on a five-point Likert scale ranging from "highly satisfied" to "not satisfied at all". These were collected at 3- and 6-month follow-ups. Adherence to supervised exercise was measured as session attendance, and adolescent self-reported adherence to home-based exercises. Adherence to the exercise therapy was poor, with adolescents participating in a median of 16 (IQR 5.5-25) out of 39 possible supervised training session. Five out of 18 adolescents had a successful outcome after both 3 and 6 months. There were no relevant changes in isometric muscle strength. This was the first study to investigate adherence to, and clinical effects of, exercise therapy and patient education in young adolescents with patellofemoral pain. Adherence to the

  12. Strength Development: Using Functional Isometrics in an Isotonic Strength Training Program.

    ERIC Educational Resources Information Center

    Jackson, Allen; And Others

    1985-01-01

    A study was made to determine if a combination of functional isometrics and standard isotonic training would be superior to a standard isotonic program in an instructional setting. The results provide support for functional isometrics as an enhancement where achievement of maximum strength is the goal. (Author/MT)

  13. Exploring the Mechanisms of Exercise-Induced Hypoalgesia Using Somatosensory and Laser Evoked Potentials

    PubMed Central

    Jones, Matthew D.; Taylor, Janet L.; Booth, John; Barry, Benjamin K.

    2016-01-01

    Exercise-induced hypoalgesia is well described, but the underlying mechanisms are unclear. The aim of this study was to examine the effect of exercise on somatosensory evoked potentials, laser evoked potentials, pressure pain thresholds and heat pain thresholds. These were recorded before and after 3-min of isometric elbow flexion exercise at 40% of the participant's maximal voluntary force, or an equivalent period of rest. Exercise-induced hypoalgesia was confirmed in two experiments (Experiment 1–SEPs; Experiment 2–LEPs) by increased pressure pain thresholds at biceps brachii (24.3 and 20.6% increase in Experiment 1 and 2, respectively; both d > 0.84 and p < 0.001) and first dorsal interosseous (18.8 and 21.5% increase in Experiment 1 and 2, respectively; both d > 0.57 and p < 0.001). In contrast, heat pain thresholds were not significantly different after exercise (forearm: 10.8% increase, d = 0.35, p = 0.10; hand: 3.6% increase, d = 0.06, p = 0.74). Contrasting effects of exercise on the amplitude of laser evoked potentials (14.6% decrease, d = −0.42, p = 0.004) and somatosensory evoked potentials (10.9% increase, d = −0.02, p = 1) were also observed, while an equivalent period of rest showed similar habituation (laser evoked potential: 7.3% decrease, d = −0.25, p = 0.14; somatosensory evoked potential: 20.7% decrease, d = −0.32, p = 0.006). The differential response of pressure pain thresholds and heat pain thresholds to exercise is consistent with relative insensitivity of thermal nociception to the acute hypoalgesic effects of exercise. Conflicting effects of exercise on somatosensory evoked potentials and laser evoked potentials were observed. This may reflect non-nociceptive contributions to the somatosensory evoked potential, but could also indicate that peripheral nociceptors contribute to exercise-induced hypoalgesia. PMID:27965587

  14. Exploring the Mechanisms of Exercise-Induced Hypoalgesia Using Somatosensory and Laser Evoked Potentials.

    PubMed

    Jones, Matthew D; Taylor, Janet L; Booth, John; Barry, Benjamin K

    2016-01-01

    Exercise-induced hypoalgesia is well described, but the underlying mechanisms are unclear. The aim of this study was to examine the effect of exercise on somatosensory evoked potentials, laser evoked potentials, pressure pain thresholds and heat pain thresholds. These were recorded before and after 3-min of isometric elbow flexion exercise at 40% of the participant's maximal voluntary force, or an equivalent period of rest. Exercise-induced hypoalgesia was confirmed in two experiments (Experiment 1-SEPs; Experiment 2-LEPs) by increased pressure pain thresholds at biceps brachii (24.3 and 20.6% increase in Experiment 1 and 2, respectively; both d > 0.84 and p < 0.001) and first dorsal interosseous (18.8 and 21.5% increase in Experiment 1 and 2, respectively; both d > 0.57 and p < 0.001). In contrast, heat pain thresholds were not significantly different after exercise (forearm: 10.8% increase, d = 0.35, p = 0.10; hand: 3.6% increase, d = 0.06, p = 0.74). Contrasting effects of exercise on the amplitude of laser evoked potentials (14.6% decrease, d = -0.42, p = 0.004) and somatosensory evoked potentials (10.9% increase, d = -0.02, p = 1) were also observed, while an equivalent period of rest showed similar habituation (laser evoked potential: 7.3% decrease, d = -0.25, p = 0.14; somatosensory evoked potential: 20.7% decrease, d = -0.32, p = 0.006). The differential response of pressure pain thresholds and heat pain thresholds to exercise is consistent with relative insensitivity of thermal nociception to the acute hypoalgesic effects of exercise. Conflicting effects of exercise on somatosensory evoked potentials and laser evoked potentials were observed. This may reflect non-nociceptive contributions to the somatosensory evoked potential, but could also indicate that peripheral nociceptors contribute to exercise-induced hypoalgesia.

  15. Hamstring Stiffness Returns More Rapidly After Static Stretching Than Range of Motion, Stretch Tolerance, and Isometric Peak Torque.

    PubMed

    Hatano, Genki; Suzuki, Shigeyuki; Matsuo, Shingo; Kataura, Satoshi; Yokoi, Kazuaki; Fukaya, Taizan; Fujiwara, Mitsuhiro; Asai, Yuji; Iwata, Masahiro

    2017-12-18

    Hamstring injuries are common, and lack of hamstring flexibility may predispose to injury. Static stretching increases range of motion (ROM) but also results in reduced muscle strength after stretching. The effects of stretching on the hamstring muscles and the duration of these effects remain unclear. To determine the effects of static stretching on the hamstrings and the duration of these effects. Randomized crossover study. University laboratory. Twenty-four healthy volunteers. We measured the torque-angle relationship (ROM, passive torque (PT) at the onset of pain, and passive stiffness) and isometric muscle force using an isokinetic dynamometer. After a 60-minute rest, the ROM of the dynamometer was set at maximum tolerable intensity; this position was maintained for 300 seconds while static passive torque (SPT) was measured continuously. We remeasured the torque-angle relationship and isometric muscle force after rest periods of 10, 20, and 30 minutes. Change in SPT during stretching; changes in ROM, PT at the onset of pain, passive stiffness, and isometric muscle force before stretching compared with 10, 20, and 30 minutes after stretching. SPT decreased significantly during stretching. Passive stiffness decreased significantly 10 and 20 minutes after stretching, but there was no significant pre- vs. post-stretching difference after 30 minutes. PT at the onset of pain and ROM increased significantly after stretching at all rest intervals, while isometric muscle force decreased significantly after all rest intervals. The effect of static stretching on passive stiffness of the hamstrings was not maintained as long as the changes in ROM, stretch tolerance, and isometric muscle force. Therefore, frequent stretching is necessary to improve the viscoelasticity of the muscle-tendon unit. Muscle force was decreased for 30 minutes after stretching; this should be considered prior to activities requiring maximal muscle strength.

  16. Normal isometric strength of rotatorcuff muscles in adults.

    PubMed

    Chezar, A; Berkovitch, Y; Haddad, M; Keren, Y; Soudry, M; Rosenberg, N

    2013-01-01

    The most prevalent disorders of the shoulder are related to the muscles of rotator cuff. In order to develop a mechanical method for the evaluation of the rotator cuff muscles, we created a database of isometric force generation by the rotator cuff muscles in normal adult population. We hypothesised the existence of variations according to age, gender and dominancy of limb. A total of 400 healthy adult volunteers were tested, classified into groups of 50 men and women for each decade of life. Maximal isometric force was measured at standardised positions for supraspinatus, infraspinatus and subscapularis muscles in both shoulders in every person. Torque of the force was calculated and normalised to lean body mass. The profiles of mean torque-time curves for each age and gender group were compared. Our data showed that men gradually gained maximal strength in the fifth decade, and showed decreased strength in the sixth. In women the maximal strength was gained in the fourth decade with gradual decline to the sixth decade of life. The dominant arm was stronger in most of the tested groups. The torque profiles of the rotator cuff muscles in men at all ages were significantly higher than that in women. We found previously unrecognised variations of rotator cuff muscles' isometric strength according to age, gender and dominancy in a normal population. The presented data may serve as a basis for the future studies for identification of the abnormal patterns of muscle isometric strength in patients with pathology of the rotator cuff muscles. Cite this article: Bone Joint Res 2013;2:214-19.

  17. Monitoring elbow isometric contraction by novel wearable fabric sensing device

    NASA Astrophysics Data System (ADS)

    Wang, Xi; Tao, Xiaoming; So, Raymond C. H.; Shu, Lin; Yang, Bao; Li, Ying

    2016-12-01

    Fabric-based wearable technology is highly desirable in sports, as it is light, flexible, soft, and comfortable with little interference to normal sport activities. It can provide accurate information on the in situ deformation of muscles in a continuous and wireless manner. During elbow flexion in isometric contraction, upper arm circumference increases with the contraction of elbow flexors, and it is possible to monitor the muscles’ contraction by limb circumferential strains. This paper presents a new wireless wearable anthropometric monitoring device made from fabric strain sensors for the human upper arm. The materials, structural design and calibration of the device are presented. Using an isokinetic testing system (Biodex3®) and the fabric monitoring device simultaneously, in situ measurements were carried out on elbow flexors in isometric contraction mode with ten subjects for a set of positions. Correlations between the measured values of limb circumferential strain and normalized torque were examined, and a linear relationship was found during isometric contraction. The average correlation coefficient between them is 0.938 ± 0.050. This wearable anthropometric device thus provides a useful index, the limb circumferential strain, for upper arm muscle contraction in isometric mode.

  18. The effect of lifelong exercise dose on cardiovascular function during exercise

    PubMed Central

    Carrick-Ranson, Graeme; Hastings, Jeffrey L.; Bhella, Paul S.; Fujimoto, Naoki; Shibata, Shigeki; Palmer, M. Dean; Boyd, Kara; Livingston, Sheryl; Dijk, Erika

    2014-01-01

    An increased “dose” of endurance exercise training is associated with a greater maximal oxygen uptake (V̇o2max), a larger left ventricular (LV) mass, and improved heart rate and blood pressure control. However, the effect of lifelong exercise dose on metabolic and hemodynamic response during exercise has not been previously examined. We performed a cross-sectional study on 101 (69 men) seniors (60 yr and older) focusing on lifelong exercise frequency as an index of exercise dose. These included 27 who had performed ≤2 exercise sessions/wk (sedentary), 25 who performed 2–3 sessions/wk (casual), 24 who performed 4–5 sessions/wk (committed) and 25 who performed ≥6 sessions/wk plus regular competitions (Masters athletes) over at least the last 25 yr. Oxygen uptake and hemodynamics [cardiac output, stroke volume (SV)] were collected at rest, two levels of steady-state submaximal exercise, and maximal exercise. Doppler ultrasound measures of LV diastolic filling were assessed at rest and during LV loading (saline infusion) to simulate increased LV filling. Body composition, total blood volume, and heart rate recovery after maximal exercise were also examined. V̇o2max increased in a dose-dependent manner (P < 0.05). At maximal exercise, cardiac output and SV were largest in committed exercisers and Masters athletes (P < 0.05), while arteriovenous oxygen difference was greater in all trained groups (P < 0.05). At maximal exercise, effective arterial elastance, an index of ventricular-arterial coupling, was lower in committed exercisers and Masters athletes (P < 0.05). Doppler measures of LV filling were not enhanced at any condition, irrespective of lifelong exercise frequency. These data suggest that performing four or more weekly endurance exercise sessions over a lifetime results in significant gains in V̇o2max, SV, and heart rate regulation during exercise; however, improved SV regulation during exercise is not coupled with favorable effects on LV

  19. Energy cost of isometric force production after active shortening in skinned muscle fibres.

    PubMed

    Joumaa, Venus; Fitzowich, Alex; Herzog, Walter

    2017-04-15

    The steady-state isometric force after active shortening of a skeletal muscle is lower than the purely isometric force at the corresponding length. This property of skeletal muscle is known as force depression. The purpose of this study was to investigate whether the energy cost of force production at the steady state after active shortening was reduced compared with the energy cost of force production for a purely isometric contraction performed at the corresponding length (same length, same activation). Experiments were performed in skinned fibres isolated from rabbit psoas muscle. Skinned fibres were actively shortened from an average sarcomere length of 3.0 µm to an average sarcomere length of 2.4 µm. Purely isometric reference contractions were performed at an average sarcomere length of 2.4 µm. Simultaneously with the force measurements, the ATP cost was measured during the last 30 s of isometric contractions using an enzyme-coupled assay. Stiffness was calculated during a quick stretch-release cycle of 0.2% fibre length performed once the steady state had been reached after active shortening and during the purely isometric reference contractions. Force and stiffness following active shortening were decreased by 10.0±1.8% and 11.0±2.2%, respectively, compared with the isometric reference contractions. Similarly, ATPase activity per second (not normalized to the force) showed a decrease of 15.6±3.0% in the force-depressed state compared with the purely isometric reference state. However, ATPase activity per second per unit of force was similar for the isometric contractions following active shortening (28.7±2.4 mmol l -1  mN -1  s mm 3 ) and the corresponding purely isometric reference contraction (30.9±2.8 mmol l -1  mN -1  s mm 3 ). Furthermore, the reduction in absolute ATPase activity per second was significantly correlated with force depression and stiffness depression. These results are in accordance with the idea that force

  20. Muscle function in aged women in response to a water-based exercises program and progressive resistance training.

    PubMed

    Bento, Paulo Cesar Barauce; Rodacki, André Luiz Felix

    2015-11-01

    The purpose of the present study was to determine the effects of a water-based exercise program on muscle function compared with regular high-intensity resistance training. Older women (n = 87) were recruited from the local community. The inclusion criteria were, to be aged 60 years or older, able to walk and able to carry out daily living activities independently. Participants were randomly assigned to one of the following groups: water-based exercises (WBG), resistance training (RTG) or control (CG). The experimental groups carried out 12 weeks of an excise program performed on water or on land. The dynamic strength, the isometric peak, and rate of torque development for the lower limbs were assessed before and after interventions. The water-based program provided a similar improvement in dynamic strength in comparison with resistance training. The isometric peak torque increased around the hip and ankle joints in the water-based group, and around the knee joint in the resistance-training group (P < 0.05). The rate of torque development increased only in the water-based group around the hip extensors muscles (P < 0.05). Water-based programs constitute an attractive alternative to promote relevant strength gains using moderate loads and fast speed movements, which were also effective to improve the capacity to generate fast torques. © 2014 Japan Geriatrics Society.

  1. Within Session Sequence of Balance and Plyometric Exercises Does Not Affect Training Adaptations with Youth Soccer Athletes.

    PubMed

    Chaouachi, Mehdi; Granacher, Urs; Makhlouf, Issam; Hammami, Raouf; Behm, David G; Chaouachi, Anis

    2017-03-01

    The integration of balance and plyometric training has been shown to provide significant improvements in sprint, jump, agility, and other performance measures in young athletes. It is not known if a specific within session balance and plyometric exercise sequence provides more effective training adaptations. The objective of the present study was to investigate the effects of using a sequence of alternating pairs of exercises versus a block (series) of all balance exercises followed by a block of plyometric exercises on components of physical fitness such as muscle strength, power, speed, agility, and balance. Twenty-six male adolescent soccer players (13.9 ± 0.3 years) participated in an 8-week training program that either alternated individual balance (e.g., exercises on unstable surfaces) and plyometric (e.g., jumps, hops, rebounds) exercises or performed a block of balance exercises prior to a block of plyometric exercises within each training session. Pre- and post-training measures included proxies of strength, power, agility, sprint, and balance such as countermovement jumps, isometric back and knee extension strength, standing long jump, 10 and 30-m sprints, agility, standing stork, and Y-balance tests. Both groups exhibited significant, generally large magnitude (effect sizes) training improvements for all measures with mean performance increases of approximately >30%. There were no significant differences between the training groups over time. The results demonstrate the effectiveness of combining balance and plyometric exercises within a training session on components of physical fitness with young adolescents. The improved performance outcomes were not significantly influenced by the within session exercise sequence.

  2. Evidence of isometric function of the flexor hallucis longus muscle in normal gait.

    PubMed

    Kirane, Y M; Michelson, J D; Sharkey, N A

    2008-01-01

    Studying mechanics of the muscles spanning multiple joints provides insights into intersegmental dynamics and movement coordination. Multiarticular muscles are thought to function at "near-isometric" lengths to transfer mechanical energy between the adjacent body segments. Flexor hallucis longus (FHL) is a multiarticular flexor of the great toe; however, its potential isometric function has received little attention. We used a robotic loading apparatus to investigate FHL mechanics during simulated walking in cadaver feet, and hypothesized that physiological force transmission across the foot can occur with isometric FHL function. The extrinsic foot tendons, stripped of the muscle fibers, were connected to computer-controlled linear actuators. The FHL activity was controlled using force-feedback (FC) based upon electromyographic data from healthy subjects, and subsequently, isometric positional feedback (PC), maintaining the FHL myotendinous junction stationary during simulated walking. Tendon forces and excursions were recorded, as were the strains within the first metatarsal. Forces in the metatarsal and metatarsophalangeal joint were derived from these strains. The FHL tendon excursion under FC was 6.57+/-3.13mm. The forces generated in the FHL tendon, metatarsal and metatarsophalangeal joint with the FHL under isometric PC were not significantly different in pattern from FC. These observations provide evidence that physiological forces could be generated along the great toe with isometric FHL function. A length servo mechanism such as the stretch reflex could likely control the isometric FHL function during in vivo locomotion; this could have interesting implications regarding the conditions of impaired stretch reflex such as spastic paresis and peripheral neuropathies.

  3. Analysis of the Hamstring Muscle Activation During two Injury Prevention Exercises

    PubMed Central

    Monajati, Alireza; Larumbe-Zabala, Eneko; Goss-Sampson, Mark

    2017-01-01

    Abstract The aim of this study was to perform an electromyographic and kinetic comparison of two commonly used hamstring eccentric strengthening exercises: Nordic Curl and Ball Leg Curl. After determining the maximum isometric voluntary contraction of the knee flexors, ten female athletes performed 3 repetitions of both the Nordic Curl and Ball Leg Curl, while knee angular displacement and electromyografic activity of the biceps femoris and semitendinosus were monitored. No significant differences were found between biceps femoris and semitendinosus activation in both the Nordic Curl and Ball Leg Curl. However, comparisons between exercises revealed higher activation of both the biceps femoris (74.8 ± 20 vs 50.3 ± 25.7%, p = 0.03 d = 0.53) and semitendinosus (78.3 ± 27.5 vs 44.3 ± 26.6%, p = 0.012, d = 0.63) at the closest knee angles in the Nordic Curl vs Ball Leg Curl, respectively. Hamstring muscles activation during the Nordic Curl increased, remained high (>70%) between 60 to 40° of the knee angle and then decreased to 27% of the maximal isometric voluntary contraction at the end of movement. Overall, the biceps femoris and semitendinosus showed similar patterns of activation. In conclusion, even though the hamstring muscle activation at open knee positions was similar between exercises, the Nordic Curl elicited a higher hamstring activity compared to the Ball Leg Curl. PMID:29339983

  4. Isometric Force Regulation in Children.

    ERIC Educational Resources Information Center

    Lazarus, Jo-Anne C.; And Others

    1995-01-01

    Isometric pinch force regulation was investigated in children and adults using a visuo-motor tracking paradigm. Younger children aged 5-7 years performed significantly worse than older children aged 9-11 years and adults in terms of an overall error score as well as a correlation score, which is believed to reflect the ability to predict the…

  5. Examining the relationship between endogenous pain modulation capacity and endurance exercise performance.

    PubMed

    Flood, Andrew; Waddington, Gordon; Cathcart, Stuart

    2017-01-01

    The aim of the current study was to examine the relationship between pain modulatory capacity and endurance exercise performance. Twenty-seven recreationally active males between 18 and 35 years of age participated in the study. Pain modulation was assessed by examining the inhibitory effect of a noxious conditioning stimulus (cuff occlusion) on the perceived intensity of a second noxious stimulus (pressure pain threshold). Participants completed two, maximal voluntary contractions followed by a submaximal endurance time task. Both performance tasks involved an isometric contraction of the non-dominant leg. The main analysis uncovered a correlation between pain modulatory capacity and performance on the endurance time task (r = -.425, p = .027), such that those with elevated pain modulation produced longer endurance times. These findings are the first to demonstrate the relationship between pain modulation responses and endurance exercise performance.

  6. Isokinetic and isometric strength in osteoarthrosis of the knee. A comparative study with healthy women.

    PubMed

    Tan, J; Balci, N; Sepici, V; Gener, F A

    1995-01-01

    Dynamic stability of the knee joint depends on the appropriate strength ratio of quadriceps and hamstring muscles. The purpose of this investigation was to determine the maximum peak torque (MPT) and MPT ratios of hamstrings to quadriceps (H/Q) muscles in patients with knee osteoarthritis (OA). Two groups of patients were included in the study. The first group consisted of 30 patients (Group A) with the clinical and radiologic findings of knee OA. The second group consisted of 30 patients (Group B) exhibiting knee joint pain without roentgenologic findings of knee OA. The findings of two patient groups were compared with each other and also with 30 healthy subjects (Group C). Isokinetic (at 60 degrees/s and at 180 degrees/s) and isometric (at 30 degrees and at 60 degrees of knee flexion) tests were performed by the rate-limiting isokinetic dynamometer system. Isokinetic and isometric MPT loss of knee flexors and extensors was found in both patient groups with respect to controls, but MPT ratios of H/Q muscles did not show a statistically significant difference compared with the control group. This may be related to the equal strength loss of knee flexors and knee extensors in patients with knee OA. It is concluded that strengthening exercises of hamstring muscles is as important as quadriceps strengthening in rehabilitation of knee OA.

  7. [Evaluation of benefits of the course of positive pressure breathing training on exercise performance].

    PubMed

    Medvedev, D V; Gorbaneva, E P; Iumatova, S N; Kuznetsova, T Iu; Solopov, I N; Katuntsev, V P

    2007-01-01

    The purpose was to evaluate effects of muscle training combined with positive pressure breathing on exercise performance of 16 runners at the age of 18-20. All subjects had the first or second-class sport qualification. The 4-wk. training course for the experimental group (n=11) included 20-25% of exercises performed in an aperture mask creating an inspiration-expiration resistance of 8-10 mm H2O. The control group (n=5) worked on the same training course but w/o positive pressure breathing. The course began and ended with the PWC170 test in order to evaluate exercise performance. Indices of external respiration and gas exchange were determined on metabolograph Ergooxyscreen (Jaeger) and lung-tester Spirosift-3000 (Fukuda). Inspiration and expiration force of the breathing muscles (mm Hg) was measured isometrically with the help of a pneumomanometer. Heart rate was calculated from ECG R-R intervals. It was stated that positive pressure breathing during muscle training increases significantly sportsmen's exercise performance due to growth of the body spare capacities, and optimization of the body systems dependence structure and efficiency.

  8. Benefits, Consequences, and Uncertainties of Conventional (Exercise) Countermeasure Approaches

    NASA Technical Reports Server (NTRS)

    Ploutz-Snyder, Lori

    2013-01-01

    This presentation will review the pros, cons, and uncertainties of using exercise countermeasures in hypothetical long duration exploration missions. The use of artificial gravity and exercise will be briefly discussed. One benefit to continued use of exercise is related to our extensive experience with spaceflight exercise hardware and programming. Exercise has been a part of each space mission dating back to the 1960's when simple isometric and bungee exercises were performed in the Gemini capsule. Over the next 50 years, exercise hardware improved cumulating in today's ISS suite of exercise equipment: Cycle Ergometer with Vibration Isolation and Stabilization System (CEVIS), Treadmill (T2) and Advanced Resistive Exercise Device (ARED). Today's exercise equipment is the most robust ever to be flown in space and allows the variety and intensity of exercise that might reasonably be expected to maintain muscle mass and function, bone density and cardiovascular fitness. A second benefit is related to the large body of research literature on exercise training. There is a considerable body of supporting research literature including >40,000 peer reviewed research articles on exercise training in humans. A third benefit of exercise is its effectiveness. With the addition of T2 and ARED to our ISS exercise suite, crew member outcomes on standard medical tests have improved. Additionally exercise has other positive side effects such as stress relief, possible improvement of immune function, improved sleep, etc. Exercise is not without its consequences. The major cons to performance of in-flight exercise are the time and equipment required. Currently crew are scheduled 2.5 hrs/day for exercise and there is considerable cost to develop, fly and maintain exercise hardware. While no major injuries have been reported on ISS, there is always some risk of injury with any form of exercise There are several uncertainties going forward; these relate mostly to the development of

  9. Circadian Phase-Shifting Effects of Bright Light, Exercise, and Bright Light + Exercise.

    PubMed

    Youngstedt, Shawn D; Kline, Christopher E; Elliott, Jeffrey A; Zielinski, Mark R; Devlin, Tina M; Moore, Teresa A

    2016-02-26

    Limited research has compared the circadian phase-shifting effects of bright light and exercise and additive effects of these stimuli. The aim of this study was to compare the phase-delaying effects of late night bright light, late night exercise, and late evening bright light followed by early morning exercise. In a within-subjects, counterbalanced design, 6 young adults completed each of three 2.5-day protocols. Participants followed a 3-h ultra-short sleep-wake cycle, involving wakefulness in dim light for 2h, followed by attempted sleep in darkness for 1 h, repeated throughout each protocol. On night 2 of each protocol, participants received either (1) bright light alone (5,000 lux) from 2210-2340 h, (2) treadmill exercise alone from 2210-2340 h, or (3) bright light (2210-2340 h) followed by exercise from 0410-0540 h. Urine was collected every 90 min. Shifts in the 6-sulphatoxymelatonin (aMT6s) cosine acrophase from baseline to post-treatment were compared between treatments. Analyses revealed a significant additive phase-delaying effect of bright light + exercise (80.8 ± 11.6 [SD] min) compared with exercise alone (47.3 ± 21.6 min), and a similar phase delay following bright light alone (56.6 ± 15.2 min) and exercise alone administered for the same duration and at the same time of night. Thus, the data suggest that late night bright light followed by early morning exercise can have an additive circadian phase-shifting effect.

  10. Isometric and isokinetic hip strength and agonist/antagonist ratios in symptomatic femoroacetabular impingement.

    PubMed

    Diamond, Laura E; Wrigley, Tim V; Hinman, Rana S; Hodges, Paul W; O'Donnell, John; Takla, Amir; Bennell, Kim L

    2016-09-01

    This study investigated isometric and isokinetic hip strength in individuals with and without symptomatic femoroacetabular impingement (FAI). The specific aims were to: (i) determine whether differences exist in isometric and isokinetic hip strength measures between groups; (ii) compare hip strength agonist/antagonist ratios between groups; and (iii) examine relationships between hip strength and self-reported measures of either hip pain or function in those with FAI. Cross-sectional. Fifteen individuals (11 males; 25±5 years) with symptomatic FAI (clinical examination and imaging (alpha angle >55° (cam FAI), and lateral centre edge angle >39° and/or positive crossover sign (combined FAI))) and 14 age- and sex-matched disease-free controls (no morphological FAI on magnetic resonance imaging) underwent strength testing. Maximal voluntary isometric contraction strength of hip muscle groups and isokinetic hip internal (IR) and external rotation (ER) strength (20°/s) were measured. Groups were compared with independent t-tests and Mann-Whitney U tests. Participants with FAI had 20% lower isometric abduction strength than controls (p=0.04). There were no significant differences in isometric strength for other muscle groups or peak isokinetic ER or IR strength. The ratio of isometric, but not isokinetic, ER/IR strength was significantly higher in the FAI group (p=0.01). There were no differences in ratios for other muscle groups. Angle of peak IR torque was the only feature correlated with symptoms. Individuals with symptomatic FAI demonstrate isometric hip abductor muscle weakness and strength imbalance in the hip rotators. Strength measurement, including agonist/antagonist ratios, may be relevant for clinical management of FAI. Copyright © 2015 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  11. Impact of exercise-induced fatigue on the strength, postural control, and gait of children with a neuromuscular disease.

    PubMed

    Hart, Raphael; Ballaz, Laurent; Robert, Maxime; Pouliot, Annie; D'Arcy, Sylvie; Raison, Maxime; Lemay, Martin

    2014-08-01

    Children with a neuromuscular disease are prone to early muscular fatigue. The objective of the present study was to evaluate the effects of fatigue induced by a walking exercise on the strength, postural control, and gait of children with a neuromuscular disease. Maximal isometric knee strength (extension and flexion), quiet standing postural control, and gait were evaluated in 12 children (8.8 [1.4] yrs) with a neuromuscular disease before and after a walking exercise. The participants were asked to stop walking when they considered themselves "very fatigued." After the exercise-induced fatigue, a significant increase in range of motion in pelvis obliquity, hip abduction and adduction, and ankle flexion and extension during gait was reported along with an increase in stride length variability. Fatigue also reduced the knee flexor strength and had a detrimental effect on postural control. Fatigue affects the strength, postural control, and gait of children with a neuromuscular disease and could notably increase the risks of falling and the occurrence of serious injuries.

  12. Effect of an individualised physical exercise program on lipid profile in sedentary patients with cardiovascular risk factors.

    PubMed

    Rubio Pérez, Francisco Javier; Franco Bonafonte, Luis; Ibarretxe Guerediaga, Daiana; Oyon Belaza, Maria Pilar; Ugarte Peyron, Paola

    Physical exercise has become in an important tool in the reduction of cardiovascular risk. To evaluate the effectiveness of an unsupervised physical exercise program that on the physical condition and the lipid profile. The final sample included 49 sedentary men and women, who were non-smokers, with dyslipidaemia, overweight, and type1 obesity. The 4-month program included walking for 30-60minutes every day, and for three days a week, 30minutes of cycling at an intensity of 40-60% of maximum functional capacity, as well as isometric abdominals and static stretching. Anthropometrics, physical condition (6minute test), and the lipid profile were evaluated before and after the physical exercise program. The objective was to achieve a caloric expenditure between 1200-2000kcal/week. At the end of the program it was observed, in both sexes, that there was a decrease in total cholesterol (P<0.02), LDL cholesterol (P<0.01), VLDL cholesterol (P<0.01), and triglycerides (P<0.05), and an increase HDL cholesterol (P<0.05). There was also an increase in the distance travelled in the 6minute test of 52m in men and 39.5m in women (P<0.002), plus a decrease in the perception of fatigue on the Borg scale of 1.19 in men, and 0.96 in women (P<0.01). There were no anthropometric changes. The physical exercise improved physical condition and the lipid profile in the sample that has been studied, with 64% of participants continuing to do it. Copyright © 2017 Sociedad Española de Arteriosclerosis. Publicado por Elsevier España, S.L.U. All rights reserved.

  13. Can exercise suppress tumour growth in advanced prostate cancer patients with sclerotic bone metastases? A randomised, controlled study protocol examining feasibility, safety and efficacy

    PubMed Central

    Newton, Robert U; Spry, Nigel A; Taaffe, Dennis R; Chambers, Suzanne K; Feeney, Kynan T; Joseph, David J; Redfern, Andrew D; Ferguson, Tom; Galvão, Daniel A

    2017-01-01

    Introduction Exercise may positively alter tumour biology through numerous modulatory and regulatory mechanisms in response to a variety of modes and dosages, evidenced in preclinical models to date. Specifically, localised and systemic biochemical alterations produced during and following exercise may suppress tumour formation, growth and distribution by virtue of altered epigenetics and endocrine–paracrine activity. Given the impressive ability of targeted mechanical loading to interfere with metastasis-driven tumour formation in human osteolytic tumour cells, it is of equal interest to determine whether a similar effect is observed in sclerotic tumour cells. The study aims to (1) establish the feasibility and safety of a combined modular multimodal exercise programme with spinal isometric training in advanced prostate cancer patients with sclerotic bone metastases and (2) examine whether targeted and supervised exercise can suppress sclerotic tumour growth and activity in spinal metastases in humans. Methods and analysis A single-blinded, two-armed, randomised, controlled and explorative phase I clinical trial combining spinal isometric training with a modular multimodal exercise programme in 40 men with advanced prostate cancer and stable sclerotic spinal metastases. Participants will be randomly assigned to (1) the exercise intervention or (2) usual medical care. The intervention arm will receive a 3-month, supervised and individually tailored modular multimodal exercise programme with spinal isometric training. Primary endpoints (feasibility and safety) and secondary endpoints (tumour morphology; biomarker activity; anthropometry; musculoskeletal health; adiposity; physical function; quality of life; anxiety; distress; fatigue; insomnia; physical activity levels) will be measured at baseline and following the intervention. Statistical analyses will include descriptive characteristics, t-tests, effect sizes and two-way (group × time) repeated

  14. Can exercise suppress tumour growth in advanced prostate cancer patients with sclerotic bone metastases? A randomised, controlled study protocol examining feasibility, safety and efficacy.

    PubMed

    Hart, Nicolas H; Newton, Robert U; Spry, Nigel A; Taaffe, Dennis R; Chambers, Suzanne K; Feeney, Kynan T; Joseph, David J; Redfern, Andrew D; Ferguson, Tom; Galvão, Daniel A

    2017-05-30

    Exercise may positively alter tumour biology through numerous modulatory and regulatory mechanisms in response to a variety of modes and dosages, evidenced in preclinical models to date. Specifically, localised and systemic biochemical alterations produced during and following exercise may suppress tumour formation, growth and distribution by virtue of altered epigenetics and endocrine-paracrine activity. Given the impressive ability of targeted mechanical loading to interfere with metastasis-driven tumour formation in human osteolytic tumour cells, it is of equal interest to determine whether a similar effect is observed in sclerotic tumour cells. The study aims to (1) establish the feasibility and safety of a combined modular multimodal exercise programme with spinal isometric training in advanced prostate cancer patients with sclerotic bone metastases and (2) examine whether targeted and supervised exercise can suppress sclerotic tumour growth and activity in spinal metastases in humans. A single-blinded, two-armed, randomised, controlled and explorative phase I clinical trial combining spinal isometric training with a modular multimodal exercise programme in 40 men with advanced prostate cancer and stable sclerotic spinal metastases. Participants will be randomly assigned to (1) the exercise intervention or (2) usual medical care. The intervention arm will receive a 3-month, supervised and individually tailored modular multimodal exercise programme with spinal isometric training. Primary endpoints (feasibility and safety) and secondary endpoints (tumour morphology; biomarker activity; anthropometry; musculoskeletal health; adiposity; physical function; quality of life; anxiety; distress; fatigue; insomnia; physical activity levels) will be measured at baseline and following the intervention. Statistical analyses will include descriptive characteristics, t-tests, effect sizes and two-way (group × time) repeated-measures analysis of variance (or analysis of

  15. Effects Of Exercise During Bed Rest

    NASA Technical Reports Server (NTRS)

    Greenleaf, John E.; Bernauer, Edmund M.

    1993-01-01

    Pair of reports adds to growing body of knowledge of physical deconditioning caused by prolonged bed rest and effectiveness of various exercise regimens in preserving or restoring fitness. Major objective to determine what regimens to prescribe to astronauts before flight, during prolonged weightlessness, and immediately before returning to Earth. Knowledge also benefits patients confined by illness or injury. First report discusses experiment on effects of two types of periodic, intense, short-duration exercise during bed rest. Experiment also discussed in documents "Effects Of Exercise During Prolonged Bed Rest" (ARC-12190), and "Isotonic And Isokinetic Exercise During Bed Rest" (ARC-12180). Second report reviews knowledge acquired with view toward development of protocols for exercise regimens.

  16. Manipulation and selective exercises decrease pelvic anteversion and low-back pain: a pilot study.

    PubMed

    Barbosa, Alexandre Carvalho; Martins, Fábio Luiz Mendonça; Barbosa, Michelle Cristina Sales Almeida; Dos Santos, Rúbia Tenile

    2013-01-01

    To study the effect of a protocol involving joint manipulation and specific exercises for pelvic stability to influence proprioceptive input to the spinal tissues and to observe the effects on sensorimotor function. Seven patients with pelvic anteversion and low back pain participated in an eight-week protocol (three sessions per week/nonconsecutive days). At each session, a high-velocity, low-amplitude manipulative thrust was applied to the sacroiliac joint, followed by quadriceps eccentric and hamstring concentric contractions. The perceived pain symptoms, pelvic anteversion as determined by photogrammetry analysis, and the electromyographic activity of the rectus femoris and lateral and medial hamstrings during flexion and extension exercises were assessed before and after treatment. Non-parametric tests were used to compare the groups before and after treatment with α=0.05. Perceived pain symptoms decreased after treatment (p=0.0007). The differences in the pelvis angles (p=0.0130) suggested significant differences between the assessments, and the electromyographic activities of all the muscles during isometric voluntary contraction increased. The eight-week manipulation/exercise protocol was effective for these subjects' needs. Further research should include a greater sample size to confirm the results and to determine the lead factors of pelvic stability.

  17. Circadian Phase-Shifting Effects of Bright Light, Exercise, and Bright Light + Exercise

    PubMed Central

    Kline, Christopher E.; Elliott, Jeffrey A.; Zielinski, Mark R.; Devlin, Tina M.; Moore, Teresa A.

    2016-01-01

    Limited research has compared the circadian phase-shifting effects of bright light and exercise and additive effects of these stimuli. The aim of this study was to compare the phase-delaying effects of late night bright light, late night exercise, and late evening bright light followed by early morning exercise. In a within-subjects, counterbalanced design, 6 young adults completed each of three 2.5-day protocols. Participants followed a 3-h ultra-short sleep-wake cycle, involving wakefulness in dim light for 2h, followed by attempted sleep in darkness for 1 h, repeated throughout each protocol. On night 2 of each protocol, participants received either (1) bright light alone (5,000 lux) from 2210–2340 h, (2) treadmill exercise alone from 2210–2340 h, or (3) bright light (2210–2340 h) followed by exercise from 0410–0540 h. Urine was collected every 90 min. Shifts in the 6-sulphatoxymelatonin (aMT6s) cosine acrophase from baseline to post-treatment were compared between treatments. Analyses revealed a significant additive phase-delaying effect of bright light + exercise (80.8 ± 11.6 [SD] min) compared with exercise alone (47.3 ± 21.6 min), and a similar phase delay following bright light alone (56.6 ± 15.2 min) and exercise alone administered for the same duration and at the same time of night. Thus, the data suggest that late night bright light followed by early morning exercise can have an additive circadian phase-shifting effect. PMID:27103935

  18. Vibration Therapy Is No More Effective Than the Standard Practice of Massage and Stretching for Promoting Recovery From Muscle Damage After Eccentric Exercise.

    PubMed

    Fuller, Joel T; Thomson, Rebecca L; Howe, Peter R C; Buckley, Jonathan D

    2015-07-01

    The purpose of this study was to determine if vibration therapy is more effective than the standard treatment of stretching and massage for improving recovery of muscle strength and reducing muscle soreness after muscle damage induced by eccentric exercise. A randomized, single-blinded parallel intervention trial design was used. Research laboratory. Fifty untrained men aged 18 to 30 years completed the study. Participants performed 100 maximal eccentric muscle actions (ECCmax) of the right knee extensor muscles. For the next 7 days, 25 participants applied cycloidal vibration therapy to the knee extensors twice daily and 25 participants performed stretching and sports massage (SSM) twice daily. Changes in markers of muscle damage [peak isometric torque (PIT), serum creatine kinase (CK), and serum myoglobin (Mb)], muscle soreness (visual analog scale), and inflammation [serum C-reactive protein (CRP)] were assessed. After ECCmax, there was no difference in recovery of PIT and muscle soreness or serum CK, Mb, and CRP levels between vibration and SSM groups (P > 0.28). Cycloidal vibration therapy is no more effective than the standard practice of stretching and massage to promote muscle recovery after the performance of muscle-damaging exercise. Prescription of vibration therapy after maximal exercise involving eccentric muscle damage did not alleviate signs and symptoms of muscle damage faster than the standard prescription of stretching and massage.

  19. Isometric deformations of unstretchable material surfaces, a spatial variational treatment

    NASA Astrophysics Data System (ADS)

    Chen, Yi-Chao; Fosdick, Roger; Fried, Eliot

    2018-07-01

    The stored energy of an unstretchable material surface is assumed to depend only upon the curvature tensor. By control of its edge(s), the surface is deformed isometrically from its planar undistorted reference configuration into an equilibrium shape. That shape is to be determined from a suitably constrained variational problem as a state of relative minimal potential energy. We pose the variational problem as one of relative minimum potential energy in a spatial form, wherein the deformation of a flat, undistorted region D in E2 to its distorted form S in E3 is assumed specified. We then apply the principle that the first variation of the potential energy, expressed as a functional over S ∪ ∂S , must vanish for all admissible variations that correspond to isometric deformations from the distorted configuration S and that also contain the essence of flatness that characterizes the reference configuration D , but is not covered by the single statement that the variation of S correspond to an isometric deformation. We emphasize the commonly overlooked condition that the spatial expression of the variational problem requires an additional variational constraint of zero Gaussian curvature to ensure that variations from S that are isometric deformations also contain the notion of flatness. In this context, it is particularly revealing to observe that the two constraints produce distinct, but essential and complementary, conditions on the first variation of S. The resulting first variation integral condition, together with the constraints, may be applied, for example, to the case of a flat, undistorted, rectangular strip D that is deformed isometrically into a closed ring S by connecting its short edges and specifying that its long edges are free of loading and, therefore, subject to zero traction and couple traction. The elementary example of a closed ring without twist as a state of relative minimum potential energy is discussed in detail, and the bending of the

  20. Influence of Maturation Status on Eccentric Exercise-Induced Muscle Damage and the Repeated Bout Effect in Females

    PubMed Central

    Lin, Ming-Ju; Nosaka, Kazunori; Ho, Chih-Chiao; Chen, Hsin-Lian; Tseng, Kuo-Wei; Ratel, Sébastien; Chen, Trevor Chung-Ching

    2018-01-01

    This study compared changes in indirect muscle damage markers, proprioception and arterial stiffness after elbow flexor eccentric exercise between pre-pubescent (9–10 y), pubescent (14–15 y), and post-pubescent (20–24 y) healthy, untrained females (n = 13/group). The maturation of the participants was confirmed by the hand bone age. All participants performed two bouts of 30 sub-maximal eccentric contractions (EC1, EC2) using a dumbbell set at 60% of pre-exercise maximal voluntary isometric elbow flexion strength at 90°. Changes in maximal voluntary concentric contraction (MVC) torque, muscle soreness (SOR), plasma creatine kinase activity, proprioception (position sense, joint reaction angle) and arterial stiffness (carotid-femoral pulse-wave velocity: cfPWV) before to 5 days after EC1 and EC2 were compared among groups by a mixed-design two-way ANOVA. Pre-exercise MVC torque and cfPWV were smaller (P < 0.05) for the pre-pubescent (MVC: 10.0 ± 0.9 Nm, cfPWV: 903 ± 60 cm/s) and the pubescent (14.3 ± 1.1 Nm, 967 ± 61 cm/s) than the post-pubescent (19.1 ± 1.4 Nm, 1,103 ± 73 cm/s). Changes in all variables after EC1 were smaller (P < 0.05) for the pre-pubescent (e.g., MVC at 1 d post-exercise: −10 ± 6%, peak SOR: 5 ± 2 mm) than the pubescent (−15 ± 9%, 12 ± 6 mm) and the post-pubescent (−25 ± 7%, 19 ± 13 mm). After EC2, changes in all variables were smaller (P < 0.05) than those after EC1 for all groups (e.g., MVC at 1 d post-exercise, pre-pubescent: −4 ± 6%, pubescent: −9 ± 4%, post-pubescent: −14 ± 5%; peak SOR: 3 ± 2, 7 ± 3, 11 ± 6 mm), but the magnitude of the repeated bout effect was not different (P > 0.05) among the groups. These results show that the extents of muscle damage, and proprioception and arterial stiffness changes after eccentric exercise are greater at later stages of maturation, but the repeated bout effect is not affected by maturation. PMID:29354073

  1. Core Muscle Activity, Exercise Preference, and Perceived Exertion during Core Exercise with Elastic Resistance versus Machine.

    PubMed

    Vinstrup, Jonas; Sundstrup, Emil; Brandt, Mikkel; Jakobsen, Markus D; Calatayud, Joaquin; Andersen, Lars L

    2015-01-01

    Objectives. To investigate core muscle activity, exercise preferences, and perceived exertion during two selected core exercises performed with elastic resistance versus a conventional training machine. Methods. 17 untrained men aged 26-67 years participated in surface electromyography (EMG) measurements of five core muscles during torso-twists performed from left to right with elastic resistance and in the machine, respectively. The order of the exercises was randomized and each exercise consisted of 3 repetitions performed at a 10 RM load. EMG amplitude was normalized (nEMG) to maximum voluntary isometric contraction (MVC). Results. A higher right erector spinae activity in the elastic exercise compared with the machine exercise (50% [95% CI 36-64] versus 32% [95% CI 18-46] nEMG) was found. By contrast, the machine exercise, compared with the elastic exercise, showed higher left external oblique activity (77% [95% CI 64-90] versus 54% [95% CI 40-67] nEMG). For the rectus abdominis, right external oblique, and left erector spinae muscles there were no significant differences. Furthermore, 76% preferred the torso-twist with elastic resistance over the machine exercise. Perceived exertion (Borg CR10) was not significantly different between machine (5.8 [95% CI 4.88-6.72]) and elastic exercise (5.7 [95% CI 4.81-6.59]). Conclusion. Torso-twists using elastic resistance showed higher activity of the erector spinae, whereas torso-twist in the machine resulted in higher activity of the external oblique. For the remaining core muscles the two training modalities induced similar muscular activation. In spite of similar perceived exertion the majority of the participants preferred the exercise using elastic resistance.

  2. The use of the isometric squat as a measure of strength and explosiveness.

    PubMed

    Bazyler, Caleb D; Beckham, George K; Sato, Kimitake

    2015-05-01

    The isometric squat has been used to detect changes in kinetic variables as a result of training; however, controversy exists in its application to dynamic multijoint tasks. Thus, the purpose of this study was to further examine the relationship between isometric squat kinetic variables and isoinertial strength measures. Subjects (17 men, 1-repetition maximum [1RM]: 148.2 ± 23.4 kg) performed squats 2 d · wk(-1) for 12 weeks and were tested on 1RM squat, 1RM partial squat, and isometric squat at 90° and 120° of knee flexion. Test-retest reliability was very good for all isometric measures (intraclass correlation coefficients > 0.90); however, rate of force development 250 milliseconds at 90° and 120° seemed to have a higher systematic error (relative technical error of measurement = 8.12%, 9.44%). Pearson product-moment correlations indicated strong relationships between isometric peak force at 90° (IPF 90°) and 1RM squat (r = 0.86), and IPF 120° and 1RM partial squat (r = 0.79). Impulse 250 milliseconds (IMP) at 90° and 120° exhibited moderate to strong correlations with 1RM squat (r = 0.70, 0.58) and partial squat (r = 0.73, 0.62), respectively. Rate of force development at 90° and 120° exhibited weak to moderate correlations with 1RM squat (r = 0.55, 0.43) and partial squat (r = 0.32, 0.42), respectively. These findings demonstrate a degree of joint angle specificity to dynamic tasks for rapid and peak isometric force production. In conclusion, an isometric squat performed at 90° and 120° is a reliable testing measure that can provide a strong indication of changes in strength and explosiveness during training.

  3. Effects of an Elastic Hamstring Assistance Device During Downhill Running

    PubMed Central

    Aldret, Randy L; Trahan, Brittany A; Davis, Greggory; Campbell, Brian; Bellar, David M

    2017-01-01

    Abstract The purpose of this study was to determine the appropriateness of using an elastic hamstring assistance device to reduce perceived levels of soreness, increase isometric strength, increase passive range of motion, and decrease biomarkers of muscle damage after eccentric exercise, specifically, downhill running This study was conducted in a university exercise physiology laboratory placing sixteen apparently healthy males (X = 21.6 ± 2.5 years) into two groups using a pre-test/post-test design. Pre-intervention measures taken included participants’ body height, body mass, body fat, capillary blood samples, VO2max, isometric hamstring strength at 45 and 90 degrees of flexion and passive hamstring range of motion. Post-intervention measures included blood biomarkers, passive range of motion, the perceived level of soreness and isometric strength. An analysis of normality of data was initially conducted followed by multivariate analysis of variance (MANOVA) of hamstring strength at 45 and 90 degrees of flexion, blood myoglobin and passive range of motion of the hamstrings. Statistically significant changes were noted in subject-perceived muscle soreness and isometric strength at 90 degrees at the 24-hour post-exercise trial measure between the two groups. Results would suggest the findings could be explained by the decrease in muscle soreness from utilizing the device during the exercise trial. Further research should be conducted to address sample size issues and to determine if the results are comparable on different surfaces. PMID:28713460

  4. 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.

  5. Isometric muscle strength and mobility capacity in children with cerebral palsy.

    PubMed

    Dallmeijer, Annet J; Rameckers, Eugene A; Houdijk, Han; de Groot, Sonja; Scholtes, Vanessa A; Becher, Jules G

    2017-01-01

    To determine the relationship between isometric leg muscle strength and mobility capacity in children with cerebral palsy (CP) compared to typically developing (TD) peers. Participants were 62 children with CP (6-13 years), able to walk with (n = 10) or without (n = 52) walking aids, and 47 TD children. Isometric muscle strength of five muscle groups of the leg was measured using hand-held dynamometry. Mobility capacity was assessed with the 1-min walk, the 10-m walk, sit-to-stand, lateral-step-up and timed-stair tests. Isometric strength of children with CP was reduced to 36-82% of TD. When adjusted for age and height, the percentage of variance in mobility capacity that was explained by isometric strength of the leg muscles was 21-24% (walking speed), 25% (sit-to-stand), 28% (lateral-step-up) and 35% (timed-stair) in children with CP. Hip abductors and knee flexors had the largest contribution to the explained variance, while knee extensors showed the weakest correlation. Weak or no associations were found between strength and mobility capacity in TD children. Isometric strength, especially hip abductor and knee flexor strength, is moderately related to mobility capacity in children with CP, but not in TD children. To what extent training of these muscle groups will lead to better mobility capacity needs further study. Implications for Rehabilitation Strength training in children with cerebral palsy (CP) may be targeted more specifically at hip abductors and knee flexors. The moderate associations imply that large improvements in mobility capacity may not be expected when strength increases.

  6. Within Session Sequence of Balance and Plyometric Exercises Does Not Affect Training Adaptations with Youth Soccer Athletes

    PubMed Central

    Chaouachi, Mehdi; Granacher, Urs; Makhlouf, Issam; Hammami, Raouf; Behm, David G; Chaouachi, Anis

    2017-01-01

    The integration of balance and plyometric training has been shown to provide significant improvements in sprint, jump, agility, and other performance measures in young athletes. It is not known if a specific within session balance and plyometric exercise sequence provides more effective training adaptations. The objective of the present study was to investigate the effects of using a sequence of alternating pairs of exercises versus a block (series) of all balance exercises followed by a block of plyometric exercises on components of physical fitness such as muscle strength, power, speed, agility, and balance. Twenty-six male adolescent soccer players (13.9 ± 0.3 years) participated in an 8-week training program that either alternated individual balance (e.g., exercises on unstable surfaces) and plyometric (e.g., jumps, hops, rebounds) exercises or performed a block of balance exercises prior to a block of plyometric exercises within each training session. Pre- and post-training measures included proxies of strength, power, agility, sprint, and balance such as countermovement jumps, isometric back and knee extension strength, standing long jump, 10 and 30-m sprints, agility, standing stork, and Y-balance tests. Both groups exhibited significant, generally large magnitude (effect sizes) training improvements for all measures with mean performance increases of approximately >30%. There were no significant differences between the training groups over time. The results demonstrate the effectiveness of combining balance and plyometric exercises within a training session on components of physical fitness with young adolescents. The improved performance outcomes were not significantly influenced by the within session exercise sequence. Key points The combination of balance and plyometric exercises can induce significant and substantial training improvements in muscle strength, power, speed, agility, and balance with adolescent youth athletes The within training session

  7. Force-time curve characteristics of dynamic and isometric muscle actions of elite women olympic weightlifters.

    PubMed

    Haff, G Gregory; Carlock, Jon M; Hartman, Michael J; Kilgore, J Lon; Kawamori, Naoki; Jackson, Janna R; Morris, Robert T; Sands, William A; Stone, Michael H

    2005-11-01

    Six elite women weightlifters were tested to evaluate force-time curve characteristics and intercorrelations of isometric and dynamic muscle actions. Subjects performed isometric and dynamic mid-thigh clean pulls at 30% of maximal isometric peak force and 100 kg from a standardized position on a 61.0 x 121.9 cm AMTI forceplate. Isometric peak force showed strong correlations to the athletes' competitive snatch, clean and jerk, and combined total (r = 0.93, 0.64, and 0.80 respectively). Isometric rate of force development showed moderate to strong relationships to the athletes' competitive snatch, clean and jerk, and combined total (r = 0.79, 0.69, and 0.80 respectively). The results of this study suggest that the ability to perform maximal snatch and clean and jerks shows some structural and functional foundation with the ability to generate high forces rapidly in elite women weightlifters.

  8. Reproducibility of isometric shoulder protraction and retraction strength measurements in normal subjects and individuals with winged scapula.

    PubMed

    Oh, Jae-Seop; Kang, Min-Hyeok; Dvir, Zeevi

    2016-11-01

    The strength of the shoulder protractors and retractors may be compromised in individuals with winged scapula (IwWS). However, no standard approach to measuring the strength of these muscles has been described. The aim of this study was to study the intra-rater and inter-rater reproducibility of a fixed-base isometric dynamometer and to describe cutoff scores for clinically meaningful change for protraction and retraction isometric strength. Twice during a week, 20 normal subjects and 20 IwWS were tested by 2 independent raters. IwWS were significantly weaker (P < .001) than control subjects in their protraction and retraction isometric strength. Excellent intra-rater and inter-rater correlations were obtained in most combinations, leading to low cutoff scores for meaningful change expressed in terms of the smallest real difference. When it is properly used, the technique described in this paper is recommended as an effective clinical tool for the quantitative assessment of protraction and retraction isometric strength, both for status determination and for monitoring of change in IwWS during and after rehabilitation. Copyright © 2016 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

  9. Explosive force production during isometric squats correlates with athletic performance in rugby union players.

    PubMed

    Tillin, Neale Anthony; Pain, Matthew Thomas Gerard; Folland, Jonathan

    2013-01-01

    This study investigated the association between explosive force production during isometric squats and athletic performance (sprint time and countermovement jump height). Sprint time (5 and 20 m) and jump height were recorded in 18 male elite-standard varsity rugby union players. Participants also completed a series of maximal- and explosive-isometric squats to measure maximal force and explosive force at 50-ms intervals up to 250 ms from force onset. Sprint performance was related to early phase (≤100 ms) explosive force normalised to maximal force (5 m, r = -0.63, P = 0.005; and 20 m, r = -0.54, P = 0.020), but jump height was related to later phase (>100 ms) absolute explosive force (0.51 < r < 0.61; 0.006 < P < 0.035). When participants were separated for 5-m sprint time (< or ≥ 1s), the faster group had greater normalised explosive force in the first 150 ms of explosive-isometric squats (33-67%; 0.001 < P < 0.017). The results suggest that explosive force production during isometric squats was associated with athletic performance. Specifically, sprint performance was most strongly related to the proportion of maximal force achieved in the initial phase of explosive-isometric squats, whilst jump height was most strongly related to absolute force in the later phase of the explosive-isometric squats.

  10. Early exercise in critically ill patients enhances short-term functional recovery.

    PubMed

    Burtin, Chris; Clerckx, Beatrix; Robbeets, Christophe; Ferdinande, Patrick; Langer, Daniel; Troosters, Thierry; Hermans, Greet; Decramer, Marc; Gosselink, Rik

    2009-09-01

    : To investigate whether a daily exercise session, using a bedside cycle ergometer, is a safe and effective intervention in preventing or attenuating the decrease in functional exercise capacity, functional status, and quadriceps force that is associated with prolonged intensive care unit stay. A prolonged stay in the intensive care unit is associated with muscle dysfunction, which may contribute to an impaired functional status up to 1 yr after hospital discharge. No evidence is available concerning the effectiveness of an early exercise training intervention to prevent these detrimental complications. : Randomized controlled trial. : Medical and surgical intensive care unit at University Hospital Gasthuisberg. : Ninety critically ill patients were included as soon as their cardiorespiratory condition allowed bedside cycling exercise (starting from day 5), given they still had an expected prolonged intensive care unit stay of at least 7 more days. : Both groups received respiratory physiotherapy and a daily standardized passive or active motion session of upper and lower limbs. In addition, the treatment group performed a passive or active exercise training session for 20 mins/day, using a bedside ergometer. : All outcome data are reflective for survivors. Quadriceps force and functional status were assessed at intensive care unit discharge and hospital discharge. Six-minute walking distance was measured at hospital discharge. No adverse events were identified during and immediately after the exercise training. At intensive care unit discharge, quadriceps force and functional status were not different between groups. At hospital discharge, 6-min walking distance, isometric quadriceps force, and the subjective feeling of functional well-being (as measured with "Physical Functioning" item of the Short Form 36 Health Survey questionnaire) were significantly higher in the treatment group (p < .05). : Early exercise training in critically ill intensive care unit

  11. Influence of Goal Contents on Exercise Addiction: Analysing the Mediating Effect of Passion for Exercise

    PubMed Central

    Sicilia, Álvaro; Alcaraz-Ibáñez, Manuel; Lirola, María-Jesús; Burgueño, Rafael

    2017-01-01

    Abstract Based on the self-determination theory (Deci and Ryan, 1985, 2000), the purpose of this study was to examine the effects of exercise goal contents on exercise addiction, taking into account the mediating effects of passion for exercise. A total of 384 university students (284 men and 100 women; Mage = 20.31, SD = 3.10) completed a questionnaire that measured exercise frequency and intensity, exercise goal contents (e.g. intrinsic: social affiliation, health management, skill development; extrinsic: image and social recognition), passion for exercise (e.g. harmonious and obsessive), and exercise addiction. After controlling the exercise frequency and intensity effects, results showed that goal contents did not directly predict exercise addiction. However, mediation analysis showed that goal contents predicted addiction through passion for exercise. These results support a motivational sequence in which extrinsic versus intrinsic goals influence exercise addiction because such goals are positively associated with obsessive passion for exercise and negatively associated with harmonious passion. PMID:29134055

  12. Influence of Goal Contents on Exercise Addiction: Analysing the Mediating Effect of Passion for Exercise.

    PubMed

    Sicilia, Álvaro; Alcaraz-Ibáñez, Manuel; Lirola, María-Jesús; Burgueño, Rafael

    2017-10-01

    Based on the self-determination theory (Deci and Ryan, 1985, 2000), the purpose of this study was to examine the effects of exercise goal contents on exercise addiction, taking into account the mediating effects of passion for exercise. A total of 384 university students (284 men and 100 women; M age = 20.31, SD = 3.10) completed a questionnaire that measured exercise frequency and intensity, exercise goal contents (e.g. intrinsic: social affiliation, health management, skill development; extrinsic: image and social recognition), passion for exercise (e.g. harmonious and obsessive), and exercise addiction. After controlling the exercise frequency and intensity effects, results showed that goal contents did not directly predict exercise addiction. However, mediation analysis showed that goal contents predicted addiction through passion for exercise. These results support a motivational sequence in which extrinsic versus intrinsic goals influence exercise addiction because such goals are positively associated with obsessive passion for exercise and negatively associated with harmonious passion.

  13. Isometric thermogenesis at rest and during movement: a neglected variable in energy expenditure and obesity predisposition.

    PubMed

    Dulloo, A G; Miles-Chan, J L; Montani, J-P; Schutz, Y

    2017-02-01

    Isometric thermogenesis as applied to human energy expenditure refers to heat production resulting from increased muscle tension. While most physical activities consist of both dynamic and static (isometric) muscle actions, the isometric component is very often essential for the optimal performance of dynamic work given its role in coordinating posture during standing, walking and most physical activities of everyday life. Over the past 75 years, there has been sporadic interest into the relevance of isometric work to thermoregulatory thermogenesis and to adaptive thermogenesis pertaining to body-weight regulation. This has been in relation to (i) a role for skeletal muscle minor tremor or microvibration - nowadays referred to as 'resting muscle mechanical activity' - in maintaining body temperature in response to mild cooling; (ii) a role for slowed skeletal muscle isometric contraction-relaxation cycle as a mechanism for energy conservation in response to caloric restriction and weight loss and (iii) a role for spontaneous physical activity (which is contributed importantly by isometric work for posture maintenance and fidgeting behaviours) in adaptive thermogenesis pertaining to weight regulation. This paper reviews the evidence underlying these proposed roles for isometric work in adaptive thermogenesis and highlights the contention that variability in this neglected component of energy expenditure could contribute to human predisposition to obesity. © 2017 World Obesity Federation.

  14. Time-to-Fatigue and Intramuscular pH Measured via NIRS During Handgrip Exercise in Trained and Sedentary Individuals

    NASA Technical Reports Server (NTRS)

    Everett, M. E.; Lee, S. M. C.; Stroud, L.; Scott, P.; Hagan, R. D.; Soller, B. R.

    2009-01-01

    In exercising muscles force production and muscular endurance are impaired by a decrease in intramuscular pH. The effects of aerobic training (AT) on preventing acidosis and prolonging exercise time in muscles not specifically targeted by the training are unknown. Purpose: To compare interstitial pH, measured non-invasively with near infrared spectroscopy (NIRS), in the flexor digitorum profundus (FDP) during rhythmic handgrip exercise in sedentary subjects and those who participate in AT activities that target the lower body. Methods: Maximal isometric force (MIF) was measured on three separate days in AT (n=5) and sedentary (n=8) subjects using a handgrip dynamometer (HGD). Isometric muscular endurance (IME) was measured during five trials, each separated by at least 48 hrs. For each IME trial subjects rhythmically squeezed (4 sec at 40% of MVC) and relaxed (2 sec) to fatigue or failure to reach the target force in three consecutive contractions or four non-consecutive contractions. Interstitial pH was derived from spectra collected using a NIRS sensor adhered to the skin over the FDP. The first four IME trials served to familiarize subjects with the protocol; the fifth trial was used for analysis. NIRS-derived pH was averaged in 30 sec increments. Between group differences in MIF and exercise time were tested using paired t-tests. A repeated measures ANOVA was used to analyze effects of AT and exercise time on pH. Results: MIF was not different between groups (mean SD; aerobic=415.6 95.4 N vs. sedentary =505.1 107.4 N). Time to fatigue was greater in the AT than in the sedentary group (mean SD: 611 173 sec vs. 377 162 sec, p<0.05). pH was not different between groups at any time point. Average pH decreased (p<0.05) in both groups from rest (pH=7.4) through 90 sec of exercise (pH=6.9), but did not decrease further throughout the remainder of exercise. Conclusion: Although between group differences in pH were not detected, differences during the onset of exercise

  15. Exercise training increases basal tone in arterioles distal to chronic coronary occlusion

    PubMed Central

    Heaps, Cristine L.; Mattox, Mildred L.; Kelly, Katherine A.; Meininger, Cynthia J.; Parker, Janet L.

    2014-01-01

    Endurance exercise training increases basal active tone in coronary arteries and enhances myogenic tone in coronary arterioles of control animals. Paradoxically, exercise training has also been shown to augment nitric oxide production and nitric oxide-mediated relaxation in coronary arterioles. The purpose of the present study was to examine the effect of exercise training on basal active tone of arterioles (~150 µm ID) isolated from the collateral-dependent region of hearts exposed to chronic coronary occlusion. Ameroid occluders were surgically placed around the proximal left circumflex coronary artery of miniature swine. Arterioles were isolated from both the collateral-dependent and nonoccluded myocardial regions of sedentary (pen confined) and exercise-trained (treadmill run; 14 wk) pigs. Coronary tone was studied in isolated arterioles using microvessel myographs and standard isometric techniques. Exposure to nominally Ca2+-free external solution reduced resting tension in all arterioles; decreases were most profound (P < 0.05) in arterioles from the collateral-dependent region of exercise-trained animals. Furthermore, nitric oxide synthase (NOS) inhibition (Nω-nitro-l-arginine methylester; 100 µM) unmasked markedly increased nitric oxide-sensitive tone in arterioles from the collateral-dependent region of exercise-trained swine. Blockade of K+ channels revealed significantly enhanced K+ channel contribution to basal tone in collateral-dependent arterioles of exercise-trained pigs. Protein content of endothelial NOS (eNOS) and phosphorylated eNOS (pS1179), determined by immunoblot, was elevated in arterioles from exercise-trained animals with the greatest effect in collateral-dependent vasculature. Taken together, we demonstrate the interaction of opposing exercise training-enhanced arteriolar basal active tone, nitric oxide production, and K+ channel activity in chronic coronary occlusion, potentially enhancing the capacity to regulate blood flow to

  16. The health effects of exercising in air pollution.

    PubMed

    Giles, Luisa V; Koehle, Michael S

    2014-02-01

    The health benefits of exercise are well known. Many of the most accessible forms of exercise, such as walking, cycling, and running often occur outdoors. This means that exercising outdoors may increase exposure to urban air pollution. Regular exercise plays a key role in improving some of the physiologic mechanisms and health outcomes that air pollution exposure may exacerbate. This problem presents an interesting challenge of balancing the beneficial effects of exercise along with the detrimental effects of air pollution upon health. This article summarizes the pulmonary, cardiovascular, cognitive, and systemic health effects of exposure to particulate matter, ozone, and carbon monoxide during exercise. It also summarizes how air pollution exposure affects maximal oxygen consumption and exercise performance. This article highlights ways in which exercisers could mitigate the adverse health effects of air pollution exposure during exercise and draws attention to the potential importance of land use planning in selecting exercise facilities.

  17. Vitamin D status and its relation to exercise performance and iron status in young ice hockey players

    PubMed Central

    Orysiak, Joanna; Mazur-Rozycka, Joanna; Fitzgerald, John; Starczewski, Michal; Malczewska-Lenczowska, Jadwiga

    2018-01-01

    Objectives The aim was to examine the association between serum vitamin D concentration and isometric strength of various muscle groups, vertical jump performance, and repeated sprint ability in young ice hockey players. The secondary aim was to determine the association between vitamin D deficiency and indices of iron status. Methods Fifty male ice hockey players (17.2±0.9 years) participated in this cross-sectional study. Exercise performance was evaluated using isometric strength measures of upper and lower extremities, vertical jump performance and repeated sprint ability (RSA). Blood samples were collected for the determination of serum 25-hydroxyvitamin D (25(OH)D) and multiple indicies of iron status. Results The mean serum 25(OH)D concentration was 30.4 ng·ml-1 and ranged from 12.5 to 91.4 ng·ml-1. Eleven participants (22%) had vitamin D deficiency and 20 athletes (40%) had vitamin D insufficiency. Serum 25(OH)D concentration was not positively correlated with isometric muscle strength, vertical jump performance, or RSA after adjusting for age, training experience, fat mass, fat free mass and height. Serum 25(OH)D concentration was not associated with indices of iron status. Conclusion Vitamin D insufficiency is highly prevalent in ice hockey players, but 25(OH)D concentration but it is not associated with exercise performance or indices of iron status. PMID:29630669

  18. The effect of contrast water therapy on symptoms of delayed onset muscle soreness.

    PubMed

    Vaile, Joanna M; Gill, Nicholas D; Blazevich, Anthony J

    2007-08-01

    This study examined the effect of contrast water therapy (CWT) on the physiological and functional symptoms of delayed onset muscle soreness (DOMS) following DOMS-inducing leg press exercise. Thirteen recreational athletes performed 2 experimental trials separated by 6 weeks in a randomized crossover design. On each occasion, subjects performed a DOMS-inducing leg press protocol consisting of 5 x 10 eccentric contractions (180 seconds recovery between sets) at 140% of 1 repetition maximum (1RM). This was followed by a 15-minute recovery period incorporating either CWT or no intervention, passive recovery (PAS). Creatine kinase concentration (CK), perceived pain, thigh volume, isometric squat strength, and weighted jump squat performance were measured prior to the eccentric exercise, immediately post recovery, and 24, 48, and 72 hours post recovery. Isometric force production was not reduced below baseline measures throughout the 72-hour data collection period following CWT ( approximately 4-10%). However, following PAS, isometric force production (mean +/- SD) was 14.8 +/- 11.4% below baseline immediately post recovery (p < 0.05), 20.8 +/- 15.6% 24 hours post recovery (p < 0.05), and 22.5 +/- 12.3% 48 hours post recovery (p < 0.05). Peak power produced during the jump squat was significantly reduced (p < 0.05) following both PAS (20.9 +/- 13.4%) and CWT (12.8 +/- 8.0%), with the mean reduction in power for PAS being marginally (not significantly) greater than for CWT (effect size = 0.76). Thigh volume measured immediately following CWT was significantly less than PAS. No significant differences in the changes in CK were found; in addition, there were no significant (p > 0.01) differences in perceived pain between treatments. Contrast water therapy was associated with a smaller reduction, and faster restoration, of strength and power measured by isometric force and jump squat production following DOMS-inducing leg press exercise when compared to PAS. Therefore, CWT

  19. Exercise for haemophilia.

    PubMed

    Strike, Karen; Mulder, Kathy; Michael, Rojer

    2016-12-19

    Haemophilia is a bleeding disorder associated with haemorrhaging into joints and muscles. Exercise is often used to aid recovery after bleeds, and to improve joint function in the presence of arthropathy. Our objective was to systematically review the available evidence on the safety and effectiveness of exercise for people with haemophilia. We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Coagulopathies Trials Register and electronic databases PubMed, OVID-Embase, and CINAHL. We hand searched abstracts from congresses of the World Federation of Hemophilia and the European Hematology Association, trial registries and the reference lists of relevant articles.Date of the last search of the Cochrane Cystic Fibrosis and Genetic Disorders Group's Coagulopathies Trials Register: 14 December 2016. Randomized or quasi-randomized controlled studies comparing any exercise intervention considered relevant in haemophilia management including supervised, unsupervised, aquatic, strengthening, aerobic or cardiovascular, stretching, proprioceptive and balance training exercise programs in males of any age with haemophilia A or B of any severity (those with co-morbidities were not excluded). Two authors reviewed the identified abstracts to determine their eligibility. For studies meeting the inclusion criteria, full articles were obtained. The two authors extracted data and assessed the risk of bias. Any disagreements were resolved by discussion. The authors contacted study investigators to obtain any missing data. Eight studies were included, which represented 233 males with all severities of haemophilia A and B, ranging in age from eight years to 49 years. Study duration ranged from four to 12 weeks. Exercise interventions varied greatly and included resistance exercises, isometric exercises, bicycle ergometry, treadmill walking and hydrotherapy; therefore, comparison between studies was difficult.None of the studies measured or reported adverse effects from

  20. Protection of muscle membrane excitability during prolonged cycle exercise with glucose supplementation.

    PubMed

    Stewart, R D; Duhamel, T A; Foley, K P; Ouyang, J; Smith, I C; Green, H J

    2007-07-01

    To determine if exercise-induced depressions in neuromuscular function are altered with oral glucose supplementation, 15 untrained participants (Vo2 peak = 45 +/- 2 ml x kg(-1) x min(-1), mean +/- SE) performed prolonged cycle exercise at approximately 60% Vo2 peak on two occasions: without glucose supplementation (NG) and with oral glucose supplementation (G). The oral G began at 30 min of exercise and was administered every 15 min (total ingested = 1.23 +/- 0.11 g carbohydrate/kg body mass). Quadriceps isometric properties and membrane excitability were assessed prior to exercise, after 90 min of exercise, and at fatigue. Cycle time to fatigue was greater (P < 0.05) in G compared with NG (137 +/- 7 vs. 115 +/- 6 min). Progressive reductions (P < 0.05) in maximal voluntary contraction (MVC, N) were observed for NG at 90 min (441 +/- 29) and at fatigue (344 +/- 33) compared with pre-exercise (666 +/- 30). At fatigue in G, the reduction in MVC was not as pronounced (P < 0.05) as in NG. Motor unit activation assessed with the interpolated twitch technique during an MVC following exercise was not different between conditions. During cycling, the G condition also resulted in a higher (P < 0.05) muscle compound potential (M-wave) amplitude (mV) at both 90 min (+50%) and at fatigue (+87%) compared with NG. Similar effects were also found M-wave area (mV/ms). These results suggest that the ergogenic effect of glucose supplementation occurs not as a result of decreased neural activation but to improved muscle function, possibly as a consequence of protection of muscle membrane excitability.

  1. Management of hypertension in actively exercising patients. Implications for drug selection.

    PubMed

    Klaus, D

    1989-02-01

    In general, rises in systolic blood pressure to over 200 mm Hg during exercise with a workload of 100W are regarded as pathological. Excessive exercise blood pressure values are to be expected in principle in all hypertensives. However, there are so far no generally accepted criteria for diagnosis of isolated systolic exercise hypertension (with normal values of resting blood pressure). The incidence of isolated systolic exercise hypertension is estimated to be about 10% of a selected population. In patients with excessive rises in blood pressure during exercise who want to engage actively in sport, general measures (reduction of obesity, restriction of alcohol and salt intake) and endurance training should be recommended initially. For endurance training, sporting activities that involve dynamic exercise are to be recommended (walking, running, mountain hiking, cycling, swimming, cross-country skiing). Activities involving isometric exercise (rowing, diving, tennis) and sport of a competitive nature are not suitable. In moderately severe and severe hypertension (diastolic blood pressure values in excess of 105 mm Hg), sporting activities and endurance training are contraindicated. If the exercise blood pressure values cannot be lowered below 220 mm Hg with the general measures mentioned, pharmacotherapy is to be considered. The drugs of choice for suppressing excessive rises in blood pressure during exercise are beta-blockers. In this group, beta 1-blockers are to be preferred to non-selective beta-blockers because of the metabolic neutrality of the former. beta-Blockers without intrinsic sympathomimetic activity (ISA) lower the blood pressure-pulse rate product more effectively than beta-blockers with ISA. Alternatively, calcium antagonists of the verapamil type and ACE inhibitors can be employed.(ABSTRACT TRUNCATED AT 250 WORDS)

  2. Body cooling in human males by cold-water immersion after vigorous exercise.

    PubMed

    McDonald, A; Goode, R C; Livingstone, S D; Duffin, J

    1984-03-01

    Five male subjects were immersed to neck level in a whole-body water calorimeter (water temperature 19 degrees C) on two occasions. One immersion was preceded by 30 min of exercise on a treadmill at 80% of the subjects' maximum heart rate, while the other was preceded by no exercise (control). Ventilation, oxygen consumption, hand-grip strength, and heat loss (measured by calorimetry) results showed no significant differences between resting and exercise trials. Minute ventilation and oxygen consumption increased during the immersion but the magnitude of the increase varied among subjects. There was a significant decrease is isometric hand-grip strength after 30 min of immersion. Rectal temperatures fell faster (0.031 degree C +/- 0.004 degree C/min) for exercised subjects than for controls (0.019 degree C +/- 0.005 degree C/min) between 10 and 45 min of immersion (P less than 0.01). It appears that vigorous preimmersion exercise may shorten survival time in cold water due to an increase in cooling rate.

  3. Effects of roller massager on muscle recovery after exercise-induced muscle damage.

    PubMed

    Casanova, Nuno; Reis, Joana F; Vaz, João R; Machado, Rita; Mendes, Bruno; Button, Duane C; Pezarat-Correia, Pedro; Freitas, Sandro R

    2018-01-01

    Two experiments (n = 10) were conducted to determine the effects of roller massager (RM) on ankle plantar flexor muscle recovery after exercise-induced muscle damage (EIMD). Experiment 1 examined both functional [i.e., ankle plantar flexion maximal isometric contraction and submaximal (30%) sustained force; ankle dorsiflexion maximal range of motion and resistance to stretch; and medial gastrocnemius pain pressure threshold] and morphological [cross-sectional area, thickness, fascicle length, and fascicle angle] variables, before and immediately, 1, 24, 48, and 72 h after an EIMD stimulus. Experiment 2 examined medial gastrocnemius deoxyhaemoglobin concentration kinetics before and 48 h after EIMD. Participants performed both experiments twice: with (RM) and without (no-roller massager; NRM) the application of a RM (6 × 45 s; 20-s rest between sets). RM intervention did not alter the functional impairment after EIMD, as well as the medial gastrocnemius morphology and oxygenation kinetics (P > 0.05). Although, an acute increase of ipsilateral (RM = + 19%, NRM = -5%, P = 0.032) and a strong tendency for contralateral (P = 0.095) medial gastrocnemius pain pressure threshold were observed. The present results suggest that a RM has no effect on plantar flexors performance, morphology, and oxygenation recovery after EIMD, except for muscle pain pressure threshold (i.e., a soreness).

  4. Do metaboreceptors alter heat loss responses following dynamic exercise?

    PubMed

    McGinn, Ryan; Swift, Brendan; Binder, Konrad; Gagnon, Daniel; Kenny, Glen P

    2014-01-01

    Metaboreceptor activation during passive heating is known to influence cutaneous vascular conductance (CVC) and sweat rate (SR). However, whether metaboreceptors modulate the suppression of heat loss following dynamic exercise remains unclear. On separate days, before and after 15 min of high-intensity treadmill running in the heat (35°C), eight males underwent either 1) no isometric handgrip exercise (IHG) or ischemia (CON), 2) 1 min IHG (60% of maximum, IHG), 3) 1 min IHG followed by 2 min of ischemia (IHG+OCC), 4) 2 min of ischemia (OCC), or 5) 1 min IHG followed by 2 min of ischemia with application of lower body negative pressure (IHG+LBNP). SR (ventilated capsule), cutaneous blood flow (Laser-Doppler), and mean arterial pressure (Finometer) were measured continuously before and after dynamic exercise. Following dynamic exercise, CVC was reduced with IHG exercise (P < 0.05) and remained attenuated with post-IHG ischemia during IHG+OCC relative to CON (39 ± 2 vs. 47 ± 6%, P < 0.05). Furthermore, the reduction in CVC was exacerbated by application of LBNP during post-IHG ischemia (35 ± 3%, P < 0.05) relative to IHG+OCC. SR increased during IHG exercise (P < 0.05) and remained elevated during post-IHG ischemia relative to CON following dynamic exercise (0.94 ± 0.15 vs. 0.53 ± 0.09 mg·min(-1)·cm(-2), P < 0.05). In contrast, application of LBNP during post-IHG ischemia had no effect on SR (0.93 ± 0.09 mg·min(-1)·cm(-2), P > 0.05) relative to post-IHG ischemia during IHG+OCC. We show that CVC is reduced and that SR is increased by metaboreceptor activation following dynamic exercise. In addition, we show that the metaboreflex-induced loading of the baroreceptors can influence the CVC response, but not the sweating response.

  5. Efficacy and feasibility of isometric arm counter-pressure manoeuvres to abort impending vasovagal syncope during real life.

    PubMed

    Croci, Francesco; Brignole, Michele; Menozzi, Carlo; Solano, Alberto; Donateo, Paolo; Oddone, Daniele; Puggioni, Enrico; Lolli, Gino

    2004-07-01

    Isometric arm exercises are able to increase blood pressure during the phase of impending vasovagal syncope. We evaluated their efficacy and feasibility during daily life in a group of 29 consecutive patients affected by vasovagal syncopes. The patients were trained to use arm tensing and/or handgrip in case of occurrence of symptoms of impending syncope. During 14+/-6 months of follow-up, 260 episodes of impending syncope were reported by 19 patients; the manoeuvres were self-administered by these patients in 98% of cases and were able to abort syncope in 99.6% of cases. Overall, 5 episodes of syncope occurred in 5 patients (17%), in 4 cases without and in 1 with activation of the manoeuvres. Syncope recurred in 4 (40%) of 10 patients aged >65 years versus only 1 (5%) of 19 patients aged < or =65 years, p=0.03. The non-responders had more episodes of impending syncope than responders (37+/-32 vs 3+/-4, p=0.001). Among 19 clinical variables, age in years was the only significant predictor of syncopal recurrence. No patients had injury or other adverse morbidity related to the relapses. Isometric arm counter-pressure manoeuvres are able to abort impending vasovagal syncope in most patients aged < or =65 years. Arm counter-pressure manoeuvres are feasible, safe and well accepted by the patients in the daily life.

  6. Developmental Changes in Isometric Strength: Longitudinal Study in Adolescent Soccer Players.

    PubMed

    Duarte, Joao P; Valente-Dos-Santos, João; Coelho-E-Silva, Manuel J; Malina, R M; Deprez, Dieter; Philippaerts, Renaat; Lenoir, Matthieu; Vaeyens, Roel

    2018-06-20

    This study aimed to examine longitudinal changes in isometric strength of the knee extensors (ImKE) and knee flexors (ImKF) at 30° and 60°. The sample was composed of 67 players aged 11.0-13.9 years at baseline over five years. Stature, body mass, skinfolds, and isometric strength (ImKE30°, ImKF30°, ImKE60° and ImKF60°) were measured. Fat mass and fat-free mass (FFM) were derived from skinfolds. Skeletal age was obtained using TW2 RUS. Multilevel random effects regression analyses extracted developmental polynomial models. An annual increment on chronological age (CA) corresponded to 5.6 N (ImKE30°: ), 2.7 N (ImKF30°: ), 4.6 N (ImKE60°: ) and 1.5 N (ImKF60°). An increment of 1 kg in FFM predicted isometric strength as follows: 1.2 N (ImKE30°), 2.1 N (ImKF30°), 3.1 N (ImKE60°) and 2.0 N (ImKF60°). The following equations were obtained: ImKE30°=5.759×CA+1.163×FFM; ImKF30°=-19.369+2.691×CA+0.693×CA 2 +2.108×FFM; ImKE60°=4.553×CA+3.134×FFM; and, ImKF60°=-19.669+1.544×CA+2.033×FFM. Although skeletal maturity had a negligible effect on dependent variables, age and body size, based on FFM, were relevant longitudinal predictors. During adolescence, systematic assessment of knee extensors and knee flexors are strongly recommended to prevent impairment of knee muscle groups. © Georg Thieme Verlag KG Stuttgart · New York.

  7. Task complexity and maximal isometric strength gains through motor learning

    PubMed Central

    McGuire, Jessica; Green, Lara A.; Gabriel, David A.

    2014-01-01

    Abstract This study compared the effects of a simple versus complex contraction pattern on the acquisition, retention, and transfer of maximal isometric strength gains and reductions in force variability. A control group (N = 12) performed simple isometric contractions of the wrist flexors. An experimental group (N = 12) performed complex proprioceptive neuromuscular facilitation (PNF) contractions consisting of maximal isometric wrist extension immediately reversing force direction to wrist flexion within a single trial. Ten contractions were completed on three consecutive days with a retention and transfer test 2‐weeks later. For the retention test, the groups performed their assigned contraction pattern followed by a transfer test that consisted of the other contraction pattern for a cross‐over design. Both groups exhibited comparable increases in strength (20.2%, P < 0.01) and reductions in mean torque variability (26.2%, P < 0.01), which were retained and transferred. There was a decrease in the coactivation ratio (antagonist/agonist muscle activity) for both groups, which was retained and transferred (35.2%, P < 0.01). The experimental group exhibited a linear decrease in variability of the torque‐ and sEMG‐time curves, indicating transfer to the simple contraction pattern (P < 0.01). The control group underwent a decrease in variability of the torque‐ and sEMG‐time curves from the first day of training to retention, but participants returned to baseline levels during the transfer condition (P < 0.01). However, the difference between torque RMS error versus the variability in torque‐ and sEMG‐time curves suggests the demands of the complex task were transferred, but could not be achieved in a reproducible way. PMID:25428951

  8. Acute Effect of Upper and Lower Body Postactivation Exercises on Shot Put Performance.

    PubMed

    Kontou, Eleni I; Berberidou, Fani T; Pilianidis, Theophilos C; Mantzouranis, Nikolaos I; Methenitis, Spyridon K

    2018-04-01

    Kontou, EI, Berberidou, FT, Pilianidis, TC, Mantzouranis, NI, and Methenitis, SK. Acute effect of upper and lower body postactivation exercises on shot put performance. J Strength Cond Res 32(4): 970-982, 2018-The purpose of this study was to investigate the effect of different types of upper and lower' extremities exercises on acute increase of shot put performance, in moderate experienced throwers. Eight (n = 8) males and 9 (n = 9) female throwers participated in this study. Their bench press and squat maximum strength were measured while their shot put performance from power position was evaluated before and after 4 interventions: (a) plyometric push-ups (Plyo), (b) 6 s isometric push-ups (Iso), (c) 3 countermovement jumps (CMJs) and (d) 10 reps. of skipping (Skip). Interventions were performed in counterbalanced order with a 48-hour interval. Significant increase (p < 0.05) of shot put performances was observed after Plyo, Iso, and CMJ (range: 2.30 ± 1.82%-5.72 ± 4.32%). In addition, Iso induced the highest increase while Skip did not induce any improvement of throwing performance. The highest increases were recorded in men's performance after CMJ (5.72 ± 4.32%) while in women's performance after Iso (3.59 ± 2.7%). Javelin and discus throwers increase higher their performance after CMJs while shot putters after Iso. Significant correlations were found between training experience, maximum/relative strength, shot put performance and increase of throwing performance (%) after the interventions (r: 0.519-0.991, p < 0.05). Percentage increase of performance between Iso and Plyo have negative correlations (r: -0.569, p < 0.05) in contrast of those between Skip and CMJ (r: 0.710, p < 0.05). These results suggest that upper or lower body postactivation interventions may acutely increase the throwing performance. However, experience and strength are significant determinant of this increase.

  9. Relationship Between Force Production During Isometric Squats and Knee Flexion Angles During Landing.

    PubMed

    Fisher, Harry; Stephenson, Mitchell L; Graves, Kyle K; Hinshaw, Taylour J; Smith, Derek T; Zhu, Qin; Wilson, Margaret A; Dai, Boyi

    2016-06-01

    Decreased knee flexion angles during landing are associated with increased anterior cruciate ligament loading. The underlying mechanisms associated with decreased self-selected knee flexion angles during landing are still unclear. The purpose of this study was to establish the relationship between the peak force production at various knee flexion angles (35, 55, 70, and 90°) during isometric squats and the actual knee flexion angles that occur during landing in both men and women. A total of 18 men and 18 women recreational/collegiate athletes performed 4 isometric squats at various knee flexion angles while vertical ground reaction forces were recorded. Participants also performed a jump-landing-jump task while lower extremity kinematics were collected. For women, significant correlations were found between the peak force production at 55 and 70° of knee flexion during isometric squats and the knee flexion angle at initial contact of landing. There were also significant correlations between the peak force production at 55, 70, and 90° of knee flexion during isometric squats and the peak knee flexion angle during landing. These correlations tended to be stronger during isometric squats at greater knee flexion compared with smaller knee flexion. No significant correlations were found for men. Posture-specific strength may play an important role in determining self-selected knee flexion angles during landing for women.

  10. Blood pressure and plasma catecholamine responses to various challenges during exercise-recovery in man.

    PubMed

    Péronnet, F; Massicotte, D; Paquet, J E; Brisson, G; de Champlain, J

    1989-01-01

    The purpose of this study was to assess the effects of a 2 h cycle exercise (50% VO2max) on heart rate (HR) and blood pressure (BP), and on plasma epinephrine (E) and norepinephrine (NE) concentrations, during the recovery period in seven normotensive subjects. Measurements were made at rest in supine (20 min) and standing (10 min) positions, during isometric exercise (hand-grip, 3 min, 25% maximal voluntary, contraction), in response to a mild psychosocial challenge (Stroop conflicting color word task) and during a 5-min period of light exercise (42 +/- 3% VO2max). Data were compared to measurements taken on another occasion under similar experimental conditions, without a previous exercise bout (control). The results showed HR to be slightly elevated in all conditions following the exercise bout. However, diastolic and systolic BP during the recovery period following exercise were not significantly different from the values observed in the control situation. Plasma NE concentrations in supine position and in response to the various physiological and/or psychosocial challenges were similar in the control situation and during the recovery period following exercise. On the other hand plasma E (nmol.1-1) was about 50% lower at rest (0.11 +/- 0.03 vs 0.23 +/- 0.04) as well as in response to hand-grip (0.21 +/- 0.04 vs 0.41 +/- 0.20) and the Stroop-test (0.21 +/- 0.05 vs 0.41 +/- 0.15) following the exercise bout.(ABSTRACT TRUNCATED AT 250 WORDS)

  11. The susceptibility of the knee extensors to eccentric exercise-induced muscle damage is not affected by leg dominance but by exercise order.

    PubMed

    Hody, S; Rogister, B; Leprince, P; Laglaine, T; Croisier, J-L

    2013-09-01

    The aims of this study were first to compare the response of dominant and non-dominant legs to eccentric exercise and second, to examine whether there is an effect of exercise order on the magnitude of symptoms associated with intense eccentric protocols. Eighteen young men performed three sets of 30 maximal eccentric isokinetic (60° s(-1)) contractions of the knee extensors (range of motion, ROM: 0°-100°, 0 = full extension) using either dominant or non-dominant leg. They repeated a similar eccentric bout using the contralateral leg 6 weeks later. The sequence of leg's use was allocated to create equally balanced groups. Four indirect markers of muscle damage including subjective pain intensity, maximal isometric strength, muscle stiffness and plasma creatine kinase (CK) activity were measured before and 24 h after exercise. All markers changed significantly following the eccentric bout performed either by dominant or non-dominant legs, but no significant difference was observed between legs. Interestingly, the comparison between the first and second eccentric bouts revealed that muscle soreness (-42%, P<0.001), CK activity (-62%, P<0.05) and strength loss (-54%, P<0.01) were significantly lower after the second bout. This study suggests that leg dominance does not influence the magnitude of exercise-induced muscle damage and supports for the first time the existence of a contralateral protection against exercise-induced muscle damage in the lower limbs. © 2013 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

  12. Diverse effects of a 445 nm diode laser on isometric contraction of the rat aorta

    PubMed Central

    Park, Sang Woong; Shin, Kyung Chul; Park, Hyun Ji; Lee, In Wha; Kim, Hyung-Sik; Chung, Soon-Cheol; Kim, Ji-Sun; Jun, Jae-Hoon; Kim, Bokyung; Bae, Young Min

    2015-01-01

    The usefulness of visible lasers in treating vascular diseases is controversial. It is probable that multiple effects of visible lasers on blood vessels and their unclear mechanisms have hampered the usefulness of this therapy. Therefore, elucidating the precise actions and mechanisms of the effects of lasers on blood vessels would provide insight into potential biomedical applications. Here, using organ chamber isometric contraction measurements, western blotting, patch-clamp, and en face immunohistochemistry, we showed that a 445 nm diode laser contracted rat aortic rings, both by activating endothelial nitric oxide synthase and by increasing oxidative stress. In addition to the effects on the endothelium, the laser also directly relaxed and contracted vascular smooth muscle by inhibiting L-type Ca2+ channels and by activating protein tyrosine kinases, respectively. Thus, we conclude that exposure to 445 nm laser might contract and dilate blood vessels in the endothelium and smooth muscle via distinct mechanisms. PMID:26417517

  13. Effects of Isometric Hand-Grip Muscle Contraction on Young Adults' Free Recall and Recognition Memory

    ERIC Educational Resources Information Center

    Tomporowski, Phillip D.; Albrecht, Chelesa; Pendleton, Daniel M.

    2017-01-01

    Purpose: The purpose of this study was to determine if physical arousal produced by isometric hand-dynamometer contraction performed during word-list learning affects young adults' free recall or recognition memory. Method: Twenty-four young adults (12 female; M[subscript age] = 22 years) were presented with 4 20-item word lists. Moderate arousal…

  14. The force dependence of isometric and concentric potentiation in mouse muscle with and without skeletal myosin light chain kinase.

    PubMed

    Gittings, William; Aggarwal, Harish; Stull, James T; Vandenboom, Rene

    2015-01-01

    The isometric potentiation associated with myosin phosphorylation is force dependent. The purpose of this study was to assess the influence of a pre-existing period of isometric force on the concentric force potentiation displayed by mouse muscles with and without the ability to phosphorylate myosin. We tested isometric (ISO) and concentric (CON) potentiation, as well as concentric potentiation after isometric force (ISO-CON), in muscles from wild-type (WT) and skeletal myosin light chain kinase-deficient (skMLCK(-/-)) mice. A conditioning stimulus increased (i.e., potentiated) mean concentric force in the ISO-CON and CON conditions to 1.31 ± 0.02 and 1.35 ± 0.02 (WT) and to 1.19 ± 0.02 and 1.21 ± 0.01 (skMLCK(-/-)) of prestimulus levels, respectively (data n = 6-8, p < 0.05). No potentiation of mean isometric force was observed in either genotype. The potentiation of mean concentric force was inversely related to relative tetanic force level (P/Po) in both genotypes. Moreover, concentric potentiation varied greatly within each contraction type and was negatively correlated with unpotentiated force in both genotypes. Thus, although no effect of pre-existing force was observed, strong and inverse relationships between concentric force potentiation and unpotentiated concentric force may suggest an influence of attached and force-generating crossbridges on potentiation magnitude in both WT and skMLCK(-/-) muscles.

  15. Effects of exercise on tumor physiology and metabolism.

    PubMed

    Pedersen, Line; Christensen, Jesper Frank; Hojman, Pernille

    2015-01-01

    Exercise is a potent regulator of a range of physiological processes in most tissues. Solid epidemiological data show that exercise training can reduce disease risk and mortality for several cancer diagnoses, suggesting that exercise training may directly regulate tumor physiology and metabolism. Here, we review the body of literature describing exercise intervention studies performed in rodent tumor models and elaborate on potential mechanistic effects of exercise on tumor physiology. Exercise has been shown to reduce tumor incidence, tumor multiplicity, and tumor growth across numerous different transplantable, chemically induced or genetic tumor models. We propose 4 emerging mechanistic effects of exercise, including (1) vascularization and blood perfusion, (2) immune function, (3) tumor metabolism, and (4) muscle-to-cancer cross-talk, and discuss these in details. In conclusion, exercise training has the potential to be a beneficial and integrated component of cancer management, but has yet to fully elucidate its potential. Understanding the mechanistic effects of exercise on tumor physiology is warranted. Insight into these mechanistic effects is emerging, but experimental intervention studies are still needed to verify the cause-effect relationship between these mechanisms and the control of tumor growth.

  16. Pressure pain and isometric strength of neck flexors are related in chronic tension-type headache.

    PubMed

    Castien, Rene; Blankenstein, Annette; De Hertogh, Willem

    2015-01-01

    In patients with chronic tension-type headache (CTTH) changes in pressure pain in the cervical region are associated with peripheral or central sensitization. It is hypothesized that an increase of isometric strength of neck flexors would lead to a decrease of pressure pain in CTTH, as an expression of reduced peripheral or central sensitization In this study we aimed to analyze the correlation between change in isometric strength of the neck flexors and change in pressure pain scores (PPS) in patients with CTTH. Comparative analysis of data from previous study. Primary healthcare center. Data from 145 patients with CTTH who underwent a manual therapy program including isometric strength training of the neck flexors were analyzed at 8 and 26 weeks post-treatment. PPS were measured as a total of pain scores on a numeric rating scale (score 0 to 10) on application of a pressure stimulus of 3kg/cm at 8 cervical- and suboccipital muscles. Isometric strength of the neck flexors was measured in seconds. Correlations were computed between changes in PPS and isometric neck flexor strength. Isometric strength of neck flexors scored significantly different compared to baseline measurement (mean 30.0 seconds, sd:25.2), and increased with a mean difference of 17.33 seconds (95%CI: 20.61 to 14.05) at 8 weeks and 19.18 seconds (95%CI: 23.48 to 14.87) at 26 weeks. Similarly, compared to PPS baseline measurement (31.6 points, sd:18.6), mean difference in PPS was significantly decreased at 8 and 26 weeks: -11.3 points (95%CI: -8.77 to -13.83) and -11.15 points (95%CI: -8.31 to -13.99). There is a negative correlation between changes in PPS and changes in isometric strength of neck flexors which is weak at 8 weeks (r = -0.243, P = 0.004) and moderate at 26 weeks (r = -0.318, P < 0.000). Correlational analysis. Decrease in PPS correlates with increases in isometric strength of neck flexors in patients with CTTH in short- and long-term.

  17. Discharge properties of abductor hallucis before, during, and after an isometric fatigue task.

    PubMed

    Kelly, Luke A; Racinais, Sebastien; Cresswell, Andrew G

    2013-08-01

    Abductor hallucis is the largest muscle in the arch of the human foot and comprises few motor units relative to its physiological cross-sectional area. It has been described as a postural muscle, aiding in the stabilization of the longitudinal arch during stance and gait. The purpose of this study was to describe the discharge properties of abductor hallucis motor units during ramp and hold isometric contractions, as well as its discharge characteristics during fatigue. Intramuscular electromyographic recordings from abductor hallucis were made in 5 subjects; from those recordings, 42 single motor units were decomposed. Data were recorded during isometric ramp contractions at 60% maximum voluntary contraction (MVC), performed before and after a submaximal isometric contraction to failure (mean force 41.3 ± 15.3% MVC, mean duration 233 ± 116 s). Motor unit recruitment thresholds ranged from 10.3 to 54.2% MVC. No significant difference was observed between recruitment and derecruitment thresholds or their respective discharge rates for both the initial and postfatigue ramp contractions (all P > 0.25). Recruitment threshold was positively correlated with recruitment discharge rate (r = 0.47, P < 0.03). All motor units attained similar peak discharge rates (14.0 ± 0.25 pulses/s) and were not correlated with recruitment threshold. Thirteen motor units could be followed during the isometric fatigue task, with a decline in discharge rate and increase in discharge rate variability occurring in the final 25% of the task (both P < 0.05). We have shown that abductor hallucis motor units discharge relatively slowly and are considerably resistant to fatigue. These characteristics may be effective for generating and sustaining the substantial level of force that is required to stabilize the longitudinal arch during weight bearing.

  18. Relation between Peak Power Output in Sprint Cycling and Maximum Voluntary Isometric Torque Production.

    PubMed

    Kordi, Mehdi; Goodall, Stuart; Barratt, Paul; Rowley, Nicola; Leeder, Jonathan; Howatson, Glyn

    2017-08-01

    From a cycling paradigm, little has been done to understand the relationships between maximal isometric strength of different single joint lower body muscle groups and their relation with, and ability to predict PPO and how they compare to an isometric cycling specific task. The aim of this study was to establish relationships between maximal voluntary torque production from isometric single-joint and cycling specific tasks and assess their ability to predict PPO. Twenty male trained cyclists participated in this study. Peak torque was measured by performing maximum voluntary contractions (MVC) of knee extensors, knee flexors, dorsi flexors and hip extensors whilst instrumented cranks measured isometric peak torque from MVC when participants were in their cycling specific position (ISOCYC). A stepwise regression showed that peak torque of the knee extensors was the only significant predictor of PPO when using SJD and accounted for 47% of the variance. However, when compared to ISOCYC, the only significant predictor of PPO was ISOCYC, which accounted for 77% of the variance. This suggests that peak torque of the knee extensors was the best single-joint predictor of PPO in sprint cycling. Furthermore, a stronger prediction can be made from a task specific isometric task. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. The effect of exercise intensity on postresistance exercise hypotension in trained men.

    PubMed

    Duncan, Michael J; Birch, Samantha L; Oxford, Samuel W

    2014-06-01

    The occurrence of postresistance exercise hypotension (PEH) after resistance exercise remains unknown. This study examined blood pressure and heart rate (HR) responses to an acute bout of low- and high-intensity resistance exercise, matched for total work, in trained males. Sixteen resistance-trained males (23.1 ± 5.9 years) performed an acute bout of low- (40% of 1 repetition maximum [1RM]) and high-intensity resistance exercise (80% 1RM), matched for total work, separated by 7 days and performed in a counterbalanced order. Systolic blood pressure (SBP) and diastolic blood pressure (DBP), mean arterial pressure (MAP), and HR were assessed before exercise, after completion of each exercise resistance exercise (3 sets of back squat, bench press, and deadlift) and every 10 minutes after resistance exercise for a period of 60 minutes. Results indicated a significant intensity × time interaction for SBP (p = 0.034, partial η(2) = 0.122) and MAP (p = 0.047, partial η(2) = 0.116) whereby SBP and MAP at 50-minute recovery and 60-minute recovery were significantly lower after high-intensity exercise (p = 0.01 for SBP and p = 0.05 for MAP in both cases) compared with low-intensity exercise. There were no significant main effects or interactions in regard to DBP (all p > 0.05). Heart rate data indicated a significant main effect for time (F(9, 135) = 2.479, p = 0.0001, partial η(2) = 0.344). Post hoc multiple comparisons indicated that HR was significantly higher after squat, bench press, and deadlift exercise compared with resting HR and HR at 40-, 50-, and 60-minute recovery (all p = 0.03). The present findings suggest that an acute bout of high intensity, but not low intensity, resistance exercise using compound movements can promote PEH in trained men.

  20. Docosahexaenoic acid affects markers of inflammation and muscle damage after eccentric exercise.

    PubMed

    DiLorenzo, Frank M; Drager, Christopher J; Rankin, Janet W

    2014-10-01

    The effect of docosahexaenoic acid (DHA) on inflammatory and muscle damage response to acute eccentric exercise and to the subsequent initiation of a resistance training program was studied in 41 untrained men. Subjects consumed either 2 g·d of either DHA or placebo (PL) for 28 days before a 17-day exercise phase (day 1 to day 17) that began with an eccentric exercise bout of the elbow flexors (day 1). For analysis, the exercise period was further divided into an acute response phase (day 1-4). Isometric muscle strength (STR), range of motion (ROM), and delayed onset muscle soreness (DOMS) were measured on days 1, 2, 3, 4, 7, 12, and 17. Fasted blood was measured for interleukin 6 (IL-6), interleukin 1 receptor antagonist, C-reactive protein (CRP), and creatine kinase (CK) on days 1, 2, and 4. Serum CK and CRP were also measured in blood collected on days 7, 12, and 17. In the acute phase, DHA significantly reduced the serum CK (12.5%) and the IL-6 response (32%) but did not affect STR or DOMS. Over the entire 17-day resistance exercise period, DOMS area under the curve was 183.2 ± 96.2 for DHA and 203.2 ± 120.9 for PL (p = 0.054) and the CK response was numerically lower for DHA (p = 0.093). Docosahexaenoic acid supplementation reduced some but not all indicators of muscle damage and inflammation in the 4 days after an acute eccentric exercise bout but did not significantly affect the response to initiation of resistance exercise.

  1. Comparison between electrically evoked and voluntary isometric contractions for biceps brachii muscle oxidative metabolism using near-infrared spectroscopy.

    PubMed

    Muthalib, Makii; Jubeau, Marc; Millet, Guillaume Y; Maffiuletti, Nicola A; Nosaka, Kazunori

    2009-09-01

    This study compared voluntary (VOL) and electrically evoked isometric contractions by muscle stimulation (EMS) for changes in biceps brachii muscle oxygenation (tissue oxygenation index, DeltaTOI) and total haemoglobin concentration (DeltatHb = oxygenated haemoglobin + deoxygenated haemoglobin) determined by near-infrared spectroscopy. Twelve men performed EMS with one arm followed 24 h later by VOL with the contralateral arm, consisting of 30 repeated (1-s contraction, 1-s relaxation) isometric contractions at 30% of maximal voluntary contraction (MVC) for the first 60 s, and maximal intensity contractions thereafter (MVC for VOL and maximal tolerable current at 30 Hz for EMS) until MVC decreased approximately 30% of pre-exercise MVC. During the 30 contractions at 30% MVC, DeltaTOI decrease was significantly (P < 0.05) greater and DeltatHb was significantly (P < 0.05) lower for EMS than VOL, suggesting that the metabolic demand for oxygen in EMS is greater than VOL at the same torque level. However, during maximal intensity contractions, although EMS torque (approximately 40% of VOL) was significantly (P < 0.05) lower than VOL, DeltaTOI was similar and tHb was significantly (P < 0.05) lower for EMS than VOL towards the end, without significant differences between the two sessions in the recovery period. It is concluded that the oxygen demand of the activated biceps brachii muscle in EMS is comparable to VOL at maximal intensity.

  2. The effect of bracing availability on one-hand isometric force exertion capability.

    PubMed

    Jones, Monica L H; Reed, Matthew P; Chaffin, Don B

    2013-01-01

    Environmental obstructions that workers encounter can kinematically limit the postures that they can achieve. However, such obstructions can also provide an opportunity for additional support by bracing with the hand, thigh or other body part. The reaction forces on bracing surfaces, which are in addition to those acting at the feet and task hand, are hypothesised to improve force exertion capability, and become required inputs to biomechanical analysis of tasks with bracing. The effects of kinematic constraints and associated bracing opportunities on isometric hand force were quantified in a laboratory study of 22 men and women. Analyses of one-hand maximal push, pull and lift tasks demonstrated that bracing surfaces available at the thighs and non-task hand enabled participants to exert an average of 43% more force at the task hand. Task hand force direction deviated significantly from the nominal direction for exertions performed with bracing at both medium and low task hand locations. This study quantifies the effect of bracing on kinematically constrained force exertions. Knowledge that appropriate bracing surfaces can substantially increase hand force is critical to the evaluation of task-oriented strength capability. Force estimates may also involve large off-axis components, which have clear implications for ergonomic analyses of manual tasks.

  3. Relationship between lower extremity isometric muscle strength and standing balance in patients with multiple sclerosis.

    PubMed

    Citaker, Seyit; Guclu-Gunduz, Arzu; Yazici, Gokhan; Bayraktar, Deniz; Nazliel, Bijen; Irkec, Ceyla

    2013-01-01

    Muscle strength and standing balance decrease in patients with Multiple Sclerosis (MS). The aim of the present study was to investigate the relationship between the lower extremity isometric muscle strength and standing balance in patients with MS. Forty-seven patients with MS and 10 healthy volunteers were included. Neurological disability level was assessed using Expanded Disability Status Scale (EDSS). Isometric strength of seven lower extremity muscles (hip flexor-extensor-abductor-adductor, knee flexor-extensor, and ankle dorsal flexor) was assessed using hand-held dynamometer. Duration of static one-leg standing balance was measured using digital chronometer. Hip flexor-extensor-abductor-adductor, knee flexor-extensor, and ankle dorsal flexor isometric muscle strength, and duration of one-leg standing balance were decreased in patients with MS when compared with controls (p < 0.05). All assessed lower extremity isometric muscle strength and EDSS level was related duration of one-leg standing balance in patients with MS. All assessed lower extremity isometric muscle strength (except ankle dorsal flexor) was related with EDSS. Hip flexor-extensor-abductor-adductor, knee flexor-extensor, and ankle dorsal flexor isometric muscle strength decreases in ambulatory MS patients. Lower extremity muscle weakness and neurological disability level are related with imbalance in MS population. Hip and knee region muscles weakness increases the neurological disability level. For the better balance and decrease neurological disability level whole lower extremity muscle strengthening should be included in rehabilitation programs.

  4. Sonomyographic responses during voluntary isometric ramp contraction of the human rectus femoris muscle.

    PubMed

    Chen, Xin; Zheng, Yong-Ping; Guo, Jing-Yi; Zhu, Zhenyu; Chan, Shing-Chow; Zhang, Zhiguo

    2012-07-01

    This paper aims to investigate the relationship between torque and muscle morphological change, which is derived from ultrasound image sequence and termed as sonomyography (SMG), during isometric ramp contraction of the rectus femoris (RF) muscle, and to further compare SMG with the electromyography (EMG) and mechanomyography (MMG), which represent the electrical and mechanical activities of the muscle. Nine subjects performed isometric ramp contraction of knee up to 90% of the maximal voluntary contraction (MVC) at speeds of 45, 22.5 and 15% MVC/s, and EMG, MMG and ultrasonography were simultaneously recorded from the RF muscle. Cross-sectional area, which was referred to as SMG, was automatically extracted from continuously captured ultrasound images using a newly developed image tracking algorithm. Polynomial regression analyses were applied to fit the EMG/MMG/SMG-to-torque relationships, and the regression coefficients of EMG, MMG, and SMG were compared. Moreover, the effect of contraction speed on SMG/EMG/MMG-to-torque relationships was tested by pair-wise comparisons of the mean relationship curves at different speeds for EMG, MMG and SMG. The results show that continuous SMG could provide important morphological parameters of continuous muscle contraction. Compared with EMG and MMG, SMG exhibits different changing patterns with the increase of torque during voluntary isometric ramp contraction, and it is less influenced by the contraction speed.

  5. The effect of six weeks endurance training on dynamic muscular control of the knee following fatiguing exercise.

    PubMed

    Hassanlouei, H; Falla, D; Arendt-Nielsen, L; Kersting, U G

    2014-10-01

    The aim of the study was to examine whether six weeks of endurance training minimizes the effects of fatigue on postural control during dynamic postural perturbations. Eighteen healthy volunteers were assigned to either a 6-week progressive endurance training program on a cycle ergometer or a control group. At week 0 and 7, dynamic exercise was performed on an ergometer until exhaustion and immediately after, the anterior-posterior centre of pressure (COP) sway was analyzed during full body perturbations. Maximal voluntary contractions (MVC) of the knee flexors and extensors, muscle fiber conduction velocity (MFCV) of the vastus lateralis and medialis during sustained isometric knee extension contractions, and power output were measured. Following the training protocol, maximum knee extensor and flexor force and power output increased significantly for the training group with no changes observed for the control group. Moreover, the reduction of MFCV due to fatigue changed for the training group only (from 8.6% to 3.4%). At baseline, the fatiguing exercise induced an increase in the centre of pressure sway during the perturbations in both groups (>10%). The fatiguing protocol also impaired postural control in the control group when measured at week 7. However, for the training group, sway was not altered after the fatiguing exercise when assessed at week 7. In summary, six weeks of endurance training delayed the onset of muscle fatigue and improved the ability to control balance in response to postural perturbations in the presence of muscle fatigue. Results implicate that endurance training should be included in any injury prevention program. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Effect of exercise timing on elevated postprandial glucose levels.

    PubMed

    Hatamoto, Yoichi; Goya, Ryoma; Yamada, Yosuke; Yoshimura, Eichi; Nishimura, Sena; Higaki, Yasuki; Tanaka, Hiroaki

    2017-08-01

    There is no consensus regarding optimal exercise timing for reducing postprandial glucose (PPG). The purpose of the present study was to determine the most effective exercise timing. Eleven participants completed four different exercise patterns 1 ) no exercise; 2 ) preprandial exercise (jogging); 3 ) postprandial exercise; and 4 ) brief periodic exercise intervention (three sets of 1-min jogging + 30 s of rest, every 30 min, 20 times total) in a random order separated by a minimum of 5 days. Preprandial and postprandial exercise consisted of 20 sets of intermittent exercise (1 min of jogging + 30 s rest per set) repeated 3 times per day. Total daily exercise volume was identical for all three exercise patterns. Exercise intensities were 62.4 ± 12.9% V̇o 2peak Blood glucose concentrations were measured continuously throughout each trial for 24 h. After breakfast, peak blood glucose concentrations were lower with brief periodic exercise (99 ± 6 mg/dl) than those with preprandial and postprandial exercise (109 ± 10 and 115 ± 14 mg/dl, respectively, P < 0.05, effect size = 0.517). After lunch, peak glucose concentrations were lower with brief periodic exercise than those with postprandial exercise (97 ± 5 and 108 ± 8 mg/dl, P < 0.05, effect size = 0.484). After dinner, peak glucose concentrations did not significantly differ among exercise patterns. Areas under the curve over 24 h and 2 h postprandially did not differ among exercise patterns. These findings suggest that brief periodic exercise may be more effective than preprandial and postprandial exercise at attenuating PPG in young active individuals. NEW & NOTEWORTHY This was the first study to investigate the effect of different exercise timing (brief periodic vs. preprandial vs. postprandial exercise) on postprandial glucose (PPG) attenuation in active healthy men. We demonstrated that brief periodic exercise attenuated peak PPG levels more than preprandial and postprandial

  7. Mouse Plantar Flexor Muscle Size and Strength After Inactivity and Training

    DTIC Science & Technology

    2010-07-01

    suspension. Keywords: eccentric contraction , microgravity , exercise . SPACEFLIGHT CAUSES atrophy and strength loss in antigravity skeletal muscles...isometric, concentric, and eccentric contractions pre- served muscle mass in the rat medial gastrocnemius ( 2 ), the use of isometric resistance exercise ...Adams GR , Haddad F , Bodell PW , Tran PD , Baldwin KM . Com- bined isometric, concentric, and eccentric resistance exercise prevents

  8. The Effect of Therapeutic Exercise on Long-Standing Adductor-Related Groin Pain in Athletes: Modified Hölmich Protocol

    PubMed Central

    Yousefzadeh, Abbas; Olyaei, Gholam Reza; Naseri, Nasrin; Khazaeipour, Zahra

    2018-01-01

    Objective The Hölmich protocol in therapeutic exercise is the most appropriate method for the treatment of long-standing adductor-related groin pain (LSAGP). Herein, we evaluated a modified Hölmich protocol to resolve the possible limitations intrinsic to the Hölmich protocol in terms of the rate of return to sport and the recovery period for athletes with LSAGP. Design The study followed a single-blind, before/after study design, where 15 athletes with LSAGP (mean age = 26.13 years; SD = 4.48) performed a 10-week modified Hölmich therapeutic exercise protocol. Results Outcome scores related to pain, hip adductor and abductor muscle strengths, and the ratio of maximum isometric and eccentric hip adduction to abduction strength increased significantly. Likewise, hip abduction and internal rotation ROM improved significantly compared to that at baseline. Furthermore, functional records (t-test, Edgren Side Step Test, and Triple Hop Test) showed significant improvement after treatment. Finally, 13 athletes (86.6% of the participants) successfully returned to sports activity in a mean time of 12.06 weeks (SD = 3.41). Conclusion The findings of this study objectively show that the modified Hölmich protocol may be safer and more effective than the Hölmich protocol in athletes with LSAGP in promoting their return to sports activity. This trial is registered with  IRCT2016080829269N1. PMID:29721339

  9. Estimation of 1RM for knee extension based on the maximal isometric muscle strength and body composition.

    PubMed

    Kanada, Yoshikiyo; Sakurai, Hiroaki; Sugiura, Yoshito; Arai, Tomoaki; Koyama, Soichiro; Tanabe, Shigeo

    2017-11-01

    [Purpose] To create a regression formula in order to estimate 1RM for knee extensors, based on the maximal isometric muscle strength measured using a hand-held dynamometer and data regarding the body composition. [Subjects and Methods] Measurement was performed in 21 healthy males in their twenties to thirties. Single regression analysis was performed, with measurement values representing 1RM and the maximal isometric muscle strength as dependent and independent variables, respectively. Furthermore, multiple regression analysis was performed, with data regarding the body composition incorporated as another independent variable, in addition to the maximal isometric muscle strength. [Results] Through single regression analysis with the maximal isometric muscle strength as an independent variable, the following regression formula was created: 1RM (kg)=0.714 + 0.783 × maximal isometric muscle strength (kgf). On multiple regression analysis, only the total muscle mass was extracted. [Conclusion] A highly accurate regression formula to estimate 1RM was created based on both the maximal isometric muscle strength and body composition. Using a hand-held dynamometer and body composition analyzer, it was possible to measure these items in a short time, and obtain clinically useful results.

  10. The effects of beetroot juice supplementation on indices of muscle damage following eccentric exercise.

    PubMed

    Clifford, Tom; Bell, Oliver; West, Daniel J; Howatson, Glyn; Stevenson, Emma J

    2016-02-01

    Foods rich in antioxidant and anti-inflammatory phytochemicals might attenuate skeletal muscle damage; thus, the present study investigated whether consuming an antioxidant rich beetroot juice would attenuate the muscle-damaging effects of eccentric exercise. Using a double blind, independent groups design, 30 recreationally active males were allocated to consume a high dose of beetroot juice (H-BT; 250 ml), a lower dose of beetroot juice (L-BT; 125 ml), or an isocaloric placebo (PLA; 250 ml) immediately (×3 servings), 24 (×2 servings) and 48 h (×2 servings) following completion of 100-drop jumps. Maximal isometric voluntary contractions (MIVC), countermovement jumps (CMJ), pressure pain threshold (PPT), creatine kinase (CK), interleukin-6 (IL-6), interleukin-8 (IL-8) and tumour necrosis factor-α (TNF-α) were measured pre, post, 2 (blood indices only), 24, 48 and 72 h following the drop jumps. CMJ performance recovered quicker (relative to baseline) in H-BT vs. PLA at 48 (91.7 ± 12.2 vs. 74.4 ± 17.3%; P = 0.009, ES = 1.00) and 72 h postexercise (93.4 ± 7.7 vs. 86 ± 5.9%; P = 0.046, ES = 1.25). PPT was greater in both the H-BT and L-BT vs. PLA at 24, 48 and 72 h postexercise (P < 0.001); PPT had returned to baseline in H-BT and L-BT at 72 h postexercise, but was still reduced in PLA (80.1 ± 28.9% of baseline values). MIVC, CK, IL-6, TNF-α and IL-8 were unaffected by beetroot juice (P > 0.05). Acute beetroot juice supplementation attenuated muscle soreness and decrements in CMJ performance induced by eccentric exercise; further research on the anti-inflammatory effects of beetroot juice are required to elucidate the precise mechanisms.

  11. Effects of Pilates and yoga in patients with chronic neck pain: A sonographic study.

    PubMed

    Uluğ, Naime; Yılmaz, Öznur Tunca; Kara, Murat; Özçakar, Levent

    2018-01-10

    Various studies have shown the efficacy of conventional isometric, Pilates and yoga exercises. However, data on the effects and comparison of these specific exercises on the cervical muscle morphology are insufficient or lacking. To investigate the effects of different exercise treatments on neck muscles in patients with chronic neck pain. A randomized study. Fifty-six patients with chronic neck pain were randomized into 3 groups as follows: Pilates group (n = 20), yoga group (n = 18) and isometric group (n = 18). Demographics and background information were recorded. The thickness and cross-sectional area of neck muscles were evaluated by ultrasound imaging. Cervical motions were measured with a goniometer. Pain severity was evaluated with the McGill Pain Scale, disability with the Neck Disability Index, quality of life with the Nottingham Health Profile, and emotional status with the Beck Depression Inventory. In addition to a conventional physio-therapy programme, 15 sessions of physical therapy, including hot pack, ultrasound, and transcutaneous electrical nerve stimulation (TENS), were provided to all patients. All groups performed the exercises for 6 weeks. The aforementioned assessments were performed before and 6 weeks after the treatment. Although pain, disability, depression and quality of life improved similarly within all groups (all p < 0.05), muscle thickness values as regards the semispinalis capitis were increased only in the Pilates group (p = 0.022). The lack of complex (progressive resistive) exercise treatment protocols, short treatment duration and partial supervision. All 3 types of exercise had favourable effects on pain and functional scores, but no differences were found among the groups, except for the Pilates group, in which the semispinalis capitis muscle increased in thickness.

  12. The effect of signal acquisition and processing choices on ApEn values: towards a "gold standard" for distinguishing effort levels from isometric force records.

    PubMed

    Forrest, Sarah M; Challis, John H; Winter, Samantha L

    2014-06-01

    Approximate entropy (ApEn) is frequently used to identify changes in the complexity of isometric force records with ageing and disease. Different signal acquisition and processing parameters have been used, making comparison or confirmation of results difficult. This study determined the effect of sampling and parameter choices by examining changes in ApEn values across a range of submaximal isometric contractions of the first dorsal interosseus. Reducing the sample rate by decimation changed both the value and pattern of ApEn values dramatically. The pattern of ApEn values across the range of effort levels was not sensitive to the filter cut-off frequency, or the criterion used to extract the section of data for analysis. The complexity increased with increasing effort levels using a fixed 'r' value (which accounts for measurement noise) but decreased with increasing effort level when 'r' was set to 0.1 of the standard deviation of force. It is recommended isometric force records are sampled at frequencies >200Hz, template length ('m') is set to 2, and 'r' set to measurement system noise or 0.1SD depending on physiological process to be distinguished. It is demonstrated that changes in ApEn across effort levels are related to changes in force gradation strategy. Copyright © 2014 IPEM. Published by Elsevier Ltd. All rights reserved.

  13. Isometric immersions and self-similar buckling in elastic sheets.

    NASA Astrophysics Data System (ADS)

    Gemmer, John

    The edges of torn elastic sheets and growing leaves often display hierarchical self-similar like buckling patterns. On the one hand, such complex, self similar patterns are usually associated with a competition between two distinct energy scales, e.g. elastic sheets with boundary conditions that preclude the possibility of relieving in plane strains, or at alloy-alloy interfaces between distinct crystal structures. On the other hand, within the non-Euclidean plate theory this complex morphology can be understood as low bending energy isometric immersions of hyperbolic Riemannian metrics. In particular, many growth patterns generate residual in-plane strains which can be entirely relieved by the sheet forming part of a surface of revolution or a helix. In this talk we will show that this complex morphology (i) arises from isometric immersions (ii) is driven by a competition between the two principal curvatures, rather than between bending and stretching. We identify the key role of branch-point (or monkey-saddle) singularities, in complex wrinkling patterns within the class of finite bending energy isometric immersions. Using these defects we will give an explicit construction of strain-free embeddings of hyperbolic surfaces that are fractal like and have lower elastic energy than their smooth counterparts US-Israel BSF Grant 2008432. NSF Grant DMS-0807501. NSF-RTG Grant DMS-1148284.

  14. Concentrically trained cyclists are not more susceptible to eccentric exercise-induced muscle damage than are stretch-shortening exercise-trained runners.

    PubMed

    Snieckus, Audrius; Kamandulis, Sigitas; Venckūnas, Tomas; Brazaitis, Marius; Volungevičius, Gintautas; Skurvydas, Albertas

    2013-03-01

    Here, we test the hypothesis that continuous concentric exercise training renders skeletal muscles more susceptible to damage in response to eccentric exercise. Elite road cyclists (CYC; n = 10, training experience 8.1 ± 2.0 years, age 22.9 ± 3.7 years), long-distance runners (LDR; n = 10, 9.9 ± 2.3 years, 24.4 ± 2.5 years), and healthy untrained (UT) men (n = 10; 22.4 ± 1.7 years) performed 100 submaximal eccentric contractions at constant angular velocity of 60° s(-1). Concentric isokinetic peak torque, isometric maximal voluntary contraction (MVC), and electrically induced knee extension torque were measured at baseline and immediately and 48 h after an eccentric exercise bout. Muscle soreness was assessed and plasma creatine kinase (CK) activity was measured at baseline and 48 h after exercise. Voluntary and electrically stimulated knee extension torque reduction were significantly greater (p < 0.05) in UT than in LDR and CYC. Immediately and 48 h after exercise, MVC decreased by 32 % and 20 % in UT, 20 % and 5 % in LDR, and 25 % and 6 % in CYC. Electrically induced 20 Hz torque decreased at the same times by 61 and 29 % in UT, 40 and 17 % in LDR, and 26 and 14 % in CYC. Muscle soreness and plasma CK activity 48 h after exercise did not differ significantly between athletes and UT subjects. In conclusion, even though elite endurance athletes are more resistant to eccentric exercise-induced muscle damage than are UT people, stretch-shortening exercise-trained LDR have no advantage over concentrically trained CYC.

  15. Changes in extracellular muscle volume affect heart rate and blood pressure responses to static exercise

    NASA Astrophysics Data System (ADS)

    Baum, K.; Essfeld, D.; Stegemann, J.

    To investigate the effect of μg-induced peripheral extracellular fluid reductions on heart rate and blood pressure during isometric exercise, six healthy male subjects performed three calf ergometer test with different extracellular volumes of working muscles. In all tests, body positions during exercise were identical (supine with the knee joint flexed to 900). After a pre-exercise period of 25 min, during which calf volumes were manipulated, subjects had to counteract an external force of 180 N for 5 min. During the pre-exercise period three different protocols were applied. Test A: Subjects rested in the exercise position; test B: Body position was the same as in A but calf volume was increased by venous congestion (cuffs inflated to 80 mm Hg); test C: Calf volumes were decreased by a negative hydrostatic pressure (calves about 40 cm above heart level with the subjects supine). To clamp the changed calf volumes in tests B and C, cuffs were inflated to 300 mm Hg 5 min before the onset of exercise. This occlusion was maintained until termination of exercise. Compared to tests A and B, the reduced volume of test C led to significant increases in heart rate and blood pressure during exercise. Oxygen uptake did not exceed resting levels in B and C until cuffs were deflated, indicating that exclusively calf muscles contributed to the neurogenic peripheral drive. It is concluded that changes in extracellular muscle volume have to be taken into account when comparing heart rate and blood pressure during lg- and μg- exercise.

  16. Effects of a giant exercising board game intervention on ambulatory physical activity among nursing home residents: a preliminary study.

    PubMed

    Mouton, Alexandre; Gillet, Nicolas; Mouton, Flore; Van Kann, Dave; Bruyère, Olivier; Cloes, Marc; Buckinx, Fanny

    2017-01-01

    This study examined the effects of a giant (4×3 m) exercising board game intervention on ambulatory physical activity (PA) and a broader array of physical and psychological outcomes among nursing home residents. A quasi-experimental longitudinal study was carried out in two comparable nursing homes. Ten participants (aged 82.5±6.3 and comprising 6 women) meeting the inclusion criteria took part in the 1-month intervention in one nursing home, whereas 11 participants (aged 89.9±3.1 with 8 women) were assigned to the control group in the other nursing home. The giant exercising board game required participants to per-form strength, flexibility, balance and endurance activities. The assistance provided by an exercising specialist decreased gradually during the intervention in an autonomy-oriented approach based on the self-determination theory. The following were assessed at baseline, after the intervention and after a follow-up period of 3 months: PA (steps/day and energy expenditure/day with ActiGraph), cognitive status (mini mental state examination), quality of life (EuroQol 5-dimensions), motivation for PA (Behavioral Regulation in Exercise Questionnaire-2), gait and balance (Tinetti and Short Physical Performance Battery), functional mobility (timed up and go), and the muscular isometric strength of the lower limb muscles. In the intervention group, PA increased from 2,921 steps/day at baseline to 3,358 steps/day after the intervention (+14.9%, P =0.04) and 4,083 steps/day (+39.8%, P =0.03) after 3 months. Energy expenditure/day also increased after the intervention (+110 kcal/day, +6.3%, P =0.01) and after 3 months (+219 kcal/day, +12.3%, P =0.02). Quality of life ( P <0.05), balance and gait ( P <0.05), and strength of the ankle ( P <0.05) were also improved after 3 months. Such improvements were not observed in the control group. The preliminary results are promising but further investigation is required to confirm and evaluate the long-term effectiveness

  17. Metabolic syndrome and hypertension: regular exercise as part of lifestyle management.

    PubMed

    Lackland, Daniel T; Voeks, Jenifer H

    2014-11-01

    The incorporation of physical activity and exercise represents a clinically important aspect in the management of metabolic syndrome, hypertension, and diabetes. While the benefit of exercise and active lifestyles is well documented for prevention and risk reduction of cardiovascular and stroke outcomes, the detailed regiment and recommendations are less clear. The components of a prescribed physical activity include consideration of activity type, frequency of an activity, activity duration, and intensity of a specific physical movement. The exercise parameters prescribed as part of the management of metabolic syndrome, diabetes, and elevated blood pressure are most often proposed as separate documents while the general recommendations are similar. The evidence is strong such that physical activity and exercise recommendations in disease management guidelines are considered high quality. The general recommendations for both blood pressure and glycemic management include a regiment of physical activity with moderate- to high-intensity exercise of 30-min bouts on multiple days with a desired goal of a total of 150 min of exercise per week. While additional research is needed to identify the specific exercise/activity mode, frequencies for exercise training, intensity levels, and duration of exercise that achieve maximal blood pressure and glycemic lowering, this general recommendation showed a consistent and significant benefit in risk reduction. Similarly, the current available evidence also indicates that aerobic exercise, dynamic resistance exercise, and isometric exercises can lower blood pressure and improve glycemic control.

  18. 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

  19. 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

  20. Effects of Exercise on Children.

    ERIC Educational Resources Information Center

    Rarick, G. Lawrence

    Exercise is generally held to be a significant factor in the growth, development, and health of children and adolescents. The effects of physical activity regimens on general growth, as well as quantitative and qualitative changes, in animal muscle and bone tissue have been clearly demonstrated. Less is known about the role of exercise and related…

  1. Pronounced effects of acute endurance exercise on gene expression in resting and exercising human skeletal muscle.

    PubMed

    Catoire, Milène; Mensink, Marco; Boekschoten, Mark V; Hangelbroek, Roland; Müller, Michael; Schrauwen, Patrick; Kersten, Sander

    2012-01-01

    Regular physical activity positively influences whole body energy metabolism and substrate handling in exercising muscle. While it is recognized that the effects of exercise extend beyond exercising muscle, it is unclear to what extent exercise impacts non-exercising muscles. Here we investigated the effects of an acute endurance exercise bouts on gene expression in exercising and non-exercising human muscle. To that end, 12 male subjects aged 44-56 performed one hour of one-legged cycling at 50% W(max). Muscle biopsies were taken from the exercising and non-exercising leg before and immediately after exercise and analyzed by microarray. One-legged cycling raised plasma lactate, free fatty acids, cortisol, noradrenalin, and adrenalin levels. Surprisingly, acute endurance exercise not only caused pronounced gene expression changes in exercising muscle but also in non-exercising muscle. In the exercising leg the three most highly induced genes were all part of the NR4A family. Remarkably, many genes induced in non-exercising muscle were PPAR targets or related to PPAR signalling, including PDK4, ANGPTL4 and SLC22A5. Pathway analysis confirmed this finding. In conclusion, our data indicate that acute endurance exercise elicits pronounced changes in gene expression in non-exercising muscle, which are likely mediated by changes in circulating factors such as free fatty acids. The study points to a major influence of exercise beyond the contracting muscle.

  2. Impaired sympathetic vascular regulation in humans after acute dynamic exercise

    NASA Technical Reports Server (NTRS)

    Halliwill, J. R.; Taylor, J. A.; Eckberg, D. L.

    1996-01-01

    1. The reduction in vascular resistance which accompanies acute dynamic exercise does not subside immediately during recovery, resulting in a post-exercise hypotension. This sustained vasodilatation suggests that sympathetic vascular regulation is altered after exercise. 2. Therefore, we assessed the baroreflex control of sympathetic outflow in response to arterial pressure changes, and transduction of sympathetic activity into vascular resistance during a sympatho-excitatory stimulus (isometric handgrip exercise) after either exercise (60 min cycling at 60% peak aerobic power (VO2,peak)) or sham treatment (60 min seated rest) in nine healthy subjects. 3. Both muscle sympathetic nerve activity and calf vascular resistance were reduced after exercise (-29.7 +/- 8.8 and -25.3 +/- 9.1%, both P < 0.05). The baroreflex relation between diastolic pressure and sympathetic outflow was shifted downward after exercise (post-exercise intercept, 218 +/- 38 total integrated activity (heartbeat)-1; post-sham intercept, 318 +/- 51 total integrated activity (heartbeat)-1, P < 0.05), indicating less sympathetic outflow across all diastolic pressures. Further, the relation between sympathetic activity and vascular resistance was attenuated after exercise (post-exercise slope, 0.0031 +/- 0.0007 units (total integrated activity)-1 min; post-sham slope, 0.0100 +/- 0.0033 units (total integrated activity)-1 min, P < 0.05), indicating less vasoconstriction with any increase in sympathetic activity. 4. Thus, both baroreflex control of sympathetic outflow and the transduction of sympathetic activity into vascular resistance are altered after dynamic exercise. We conclude that the vasodilation which underlies post-exercise hypotension results from both neural and vascular phenomena.

  3. [Health and exercise: effects of exercise on high blood pressure].

    PubMed

    Ikeda, M; Nanri, H; Himeno, E

    1993-09-01

    Many factors, such as genetic, psychological, environmental, and socioeconomical factors, influence the health of individuals. Recently behavioral risks which cause preventable chronic diseases or premature death have been increasing. These risk factors are mainly due to living habits, such as over-eating, less exercise and psychological stress. Physical activity or fitness is reported to be inversely associated with morbidity and mortality from chronic diseases, such as cardiovascular diseases diabetes mellitus, cancer and so on. Hypertension has also been reported to be associated with low physical fitness in cross-sectional studies. We have so far reported a significant blood pressure reduction in mild hypertensive patients who completed mild intensity exercise training in well controlled studies. Exercise seemed to modify the multiple factors that might participate in raising and maintaining high blood pressure. The mechanisms of lowering blood pressure by exercise training are mainly due to a depletion of blood volume or the reduction of both cardiac output and the sympathetic tone. They were supported by the evidence of increased levels of prostaglandin E, dopamine, taurine, and decreased levels of plasma norepinephrine and endogenous ouavain-like substance. In this article, we have reviewed the physiological and biochemical roles of exercise, the effects of exercise on high blood pressure, and the hypotensive mechanism of mild aerobic exercise hypertensive patients.

  4. Comparison between the effects of 4 different electrical stimulation current waveforms on isometric knee extension torque and perceived discomfort in healthy women.

    PubMed

    Dantas, Lucas Ogura; Vieira, Amilton; Siqueira, Aristides Leite; Salvini, Tania Fatima; Durigan, João Luiz Quagliotti

    2015-01-01

    We studied the effects of different neuromuscular electrical stimulation (NMES) currents, 2 kHz-frequency alternating currents (KACs, Russian and Aussie) and 2 pulsed currents (PCs), on isometric knee extension torque and discomfort level, both in isolation and combined, with maximum voluntary contraction (MVC). Twenty-one women (age 21.6 ± 2.5 years) were studied. We evaluated torque evoked by NMES or NMES combined with maximum voluntary contraction of the quadriceps muscle of healthy women. Discomfort level was measured using a visual analog pain scale. Despite comparable levels of discomfort, evoked torque was lower for Russian current compared with the other modalities (Russian 50.8%, Aussie 71.7%, PC500 76.9%, and PC200 70.1%; P < 0.001). There was no advantage in combining NMES with MVC compared with isolated NMES. The Aussie and PC approaches proved superior to Russian current for inducing isometric knee extension torque. This information is important in guiding decision making with regard to NMES protocols for muscle strengthening. © 2014 Wiley Periodicals, Inc.

  5. Effects of exercise on brown and beige adipocytes.

    PubMed

    Dewal, Revati S; Stanford, Kristin I

    2018-04-21

    Physical exercise leads to beneficial effects in numerous tissues and organ systems and offers protection against obesity and type 2 diabetes. Recent studies have investigated the role of exercise on brown adipose tissue (BAT) and white adipose tissue (WAT), and have indicated marked adaptations to each tissue with exercise. Studies investigating the effects of exercise on BAT have produced conflicting results, with some showing an increase in the thermogenic activity of BAT and some demonstrating a decrease in the thermogenic activity of BAT. Human studies have observed a down-regulation of BAT activity (measured by a reduction in glucose uptake) in response to exercise. In WAT, exercise decreases adipocyte size, alters gene expression, and increases mitochondrial activity. Transplantation of exercise-trained subcutaneous WAT (scWAT) improves whole-body metabolic health. In rodents, exercise also results in a beiging of scWAT. Thus, exercise-induced changes to adipose tissue may be part of the mechanism by which exercise improves metabolic health. Copyright © 2018 The Author(s). Published by Elsevier B.V. All rights reserved.

  6. Acute Cardiovascular Response during Resistance Exercise with Whole-body Vibration in Sedentary Subjects: A Randomized Cross-over Trial.

    PubMed

    Dias, Thaisa; Polito, Marcos

    2015-01-01

    This study aimed to compare the acute cardiovascular responses during and after resistance exercise with and without whole-body vibration. Nineteen sedentary adults randomly performed one session of isometric squats without vibration and the same exercise with vibration. Systolic (SBP) and diastolic blood pressure (DBP), heart rate (HR), stroke volume (SV), cardiac output (CO) and systemic vascular resistance (SVR) were measured. SBP, DBP and HR were also measured for 20 min after the sessions. The exercise with vibration demonstrated significant values ​​(P < 0.05) for SBP (second to sixth sets), DBP (third to sixth sets) and SVR (second to sixth sets) compared with the exercise without vibration. After the sessions, the values ​​of SBP for both exercises were significantly lower than the respective resting values; with no difference between the sessions. In conclusion, exercise with vibration caused increases in SBP, DBP and SVR compared with exercise with no vibration in sedentary adults.

  7. The effects of control-display gain on performance of race car drivers in an isometric braking task.

    PubMed

    de Winter, J C F; de Groot, S

    2012-12-01

    To minimise lap times during car racing, it is important to build up brake forces rapidly and maintain precise control. We examined the effect of the amplification factor (gain) between brake pedal force and a visually represented output value on a driver's ability to track a target value. The test setup was a formula racing car cockpit fitted with an isometric brake pedal. Thirteen racing drivers performed tracking tasks with four control-display gains and two target functions: a step function (35 trials per gain) and a multisine function (15 trials per gain). The control-display gain had only minor effects on root mean-squared error between output value and target value, but it had large effects on build-up speed, overshoot, within-participants variability, and self-reported physical load. The results confirm the hypothesis that choosing an optimum gain involves balancing stability against physical effort.

  8. The effects of aerobic exercise and strengthening exercise on pain pressure thresholds.

    PubMed

    Lee, Han Suk

    2014-07-01

    [Purpose] We assessed the effects of aerobic exercise and strengthening exercise on pain pressure thresholds (PPTs) over time. [Subjects and Methods] Fifteen healthy participants were recruited and randomly divided into 3 groups: aerobic exercise, strengthening exercise, and control. The subjects in the aerobic group walked on a treadmill for 40 min at 6.5 km/h. The subjects in the strength group performed circuit training that included bench press, lat pull down, biceps curl, triceps extension, and shoulder press based on the perceived exertion for 40 min. The subjects in the control group rested without any exercise in a quiet room for 40 min. The PPTs of 5 potential muscle trigger points before exercise, and immediately after 10 and 40 min of exercise or rest were measured using an electronic algometer (JTECH Medical, USA). The Friedman's, Kruskal-Wallis, and Mann-Whitney tests were performed using SPSS 18.0 (IBM, Korea). [Results] The PPTs of all subjects decreased after 10 min of exercise, but the difference was not statistically significant. The PPTs of the control group decreased after 40 min. Furthermore, the PPTs of 3 muscles increased after 40 min of aerobic exercise and of 6 muscles after 40 min of strengthening exercise. No significant difference in PPTs was noted among the groups. [Conclusion] The results show that 40 min is a more appropriate exercise time, although the efficacy of controlling pain did not differ between strengthening exercise and aerobic exercise.

  9. [The impact of dynamic platform exercises on knee joint muscle strength in patients with gonarthrosis treated with microfracture method].

    PubMed

    Klupiński, Kamil; Krochmalski, Jakub; Woldańska-Okońska, Marta

    2017-06-23

    Osteoarthritis is the most common joint disease. Gonarthrosis is one of the most serious diseases the highly developed modern medicine must face. The number of patients suffering from joint pain and progressive disability is growing, especially in economically developed countries. Over the years, the disease has been considered merely as a symptom of aging and the effect of "wear and tear" of the cartilage. At present it is known that the degenerative joint disease is of chronic and progressive nature and its pathogenesis is complex. The aim of the study was to determine the impact of dynamic platform exercises on knee joint muscle strength in patients with gonarthrosis treated with microfracture method. The study included 120 patients of both sexes, aged 40 to 65 years, height range1.60-1.90 m., weight 50- 100 kg. Patients were divided into two groups. Group I of 60 patients after knee arthroscopy (with performed microfractures on the articular cartilage) who were subjected to physiotherapy with the use of dynamometric platform and to isometric and dynamic exercises of muscles surrounding the knee joint. Group II (control) of 60 patients after knee arthroscopy (with performed microfractures on the articular cartilage), who were subjected only to isometric and dynamic exercises of muscles surrounding the knee joint. The patients underwent rehabilitation according to the same rehabilitation program suggested by the Medical Magnus Clinic in Lodz, which consisted in performing daily exercises in open and closed kinetic chains. All Group I and II patients were examined three times: before the start of the rehabilitation, after 4th week of rehabilitation (on the average 20 days of the procedures) and 3 months afterwards. The clinical examination included the measurement of muscle strength using Lovett test. It has been demonstrated that the introduction of modern highly specialized physiotherapy contributes to the improvement of the outcome and to the shortening of the

  10. Pronounced Effects of Acute Endurance Exercise on Gene Expression in Resting and Exercising Human Skeletal Muscle

    PubMed Central

    Catoire, Milène; Mensink, Marco; Boekschoten, Mark V.; Hangelbroek, Roland; Müller, Michael; Schrauwen, Patrick; Kersten, Sander

    2012-01-01

    Regular physical activity positively influences whole body energy metabolism and substrate handling in exercising muscle. While it is recognized that the effects of exercise extend beyond exercising muscle, it is unclear to what extent exercise impacts non-exercising muscles. Here we investigated the effects of an acute endurance exercise bouts on gene expression in exercising and non-exercising human muscle. To that end, 12 male subjects aged 44–56 performed one hour of one-legged cycling at 50% Wmax. Muscle biopsies were taken from the exercising and non-exercising leg before and immediately after exercise and analyzed by microarray. One-legged cycling raised plasma lactate, free fatty acids, cortisol, noradrenalin, and adrenalin levels. Surprisingly, acute endurance exercise not only caused pronounced gene expression changes in exercising muscle but also in non-exercising muscle. In the exercising leg the three most highly induced genes were all part of the NR4A family. Remarkably, many genes induced in non-exercising muscle were PPAR targets or related to PPAR signalling, including PDK4, ANGPTL4 and SLC22A5. Pathway analysis confirmed this finding. In conclusion, our data indicate that acute endurance exercise elicits pronounced changes in gene expression in non-exercising muscle, which are likely mediated by changes in circulating factors such as free fatty acids. The study points to a major influence of exercise beyond the contracting muscle. PMID:23226462

  11. [Effect of atorvastatin on exercise tolerance in patients with diastolic dysfunction and exercise-induced hypertension].

    PubMed

    Ye, Ping-xian; Ye, Ping-zhen; Zhu, Jian-hua; Chen, Wei; Gao, Dan-chen

    2014-05-01

    To investigate the effect of atorvastatin on exercise tolerance in patients with diastolic dysfunction and exercise-induced hypertension. A randomized, double-blind, placebo-controlled prospective study was performed. Sixty patients with diastolic dysfunction (mitral flow velocity E/A <1) and exercise-induced hypertension (SBP>200 mm Hg) treated with atorvastatin (20 mg q.d) or placebo for 1 year. Cardiopulmonary exercise test and exercise blood pressure measurement were performed. Plasma B-natriuretic peptide (BNP) concentration at rest and at peak exercise, plasma high sensitive-C reaction protein (hs-CRP) and endothelin (ET) concentration were determined at baseline and after treatment. After treatment by atorvastatin, the resting SBP, pulse pressure, the peak exercise SBP and BNP were significantly decreased; and the exercise time, metabolic equivalent, maximal oxygen uptake and anaerobic threshold were increased. All of these parameters had significant differences with baseline levels (P<0.05) and the rest pulse pressure, the peak exercise SBP and BNP, and the exercise time had significant differences compared with placebo treatment (P<0.05). Plasma concentrations of hs-CRP and ET were markedly reduced by atorvastatin treatment compared with baseline and placebo (P<0.05). No difference in above parameters was found before and after placebo treatment (P>0.05). In patients with diastolic dysfunction at rest and exercise-induced hypertension, atorvastatin can effectively reduce plasma hs-CRP and ET level, lower blood pressure and peak exercise SBP, decrease peak exercise plasma BNP concentration, and ultimately improve exercise tolerance.

  12. Caffeine-induced increase in voluntary activation and strength of the quadriceps muscle during isometric, concentric and eccentric contractions.

    PubMed

    Behrens, Martin; Mau-Moeller, Anett; Weippert, Matthias; Fuhrmann, Josefin; Wegner, Katharina; Skripitz, Ralf; Bader, Rainer; Bruhn, Sven

    2015-05-13

    This study investigated effects of caffeine ingestion (8 mg/kg) on maximum voluntary torque (MVT) and voluntary activation of the quadriceps during isometric, concentric and eccentric contractions. Fourteen subjects ingested caffeine and placebo in a randomized, controlled, counterbalanced, double-blind crossover design. Neuromuscular tests were performed before and 1 h after oral caffeine and placebo intake. MVTs were measured and the interpolated twitch technique was applied during isometric, concentric and eccentric contractions to assess voluntary activation. Furthermore, normalized root mean square of the EMG signal was calculated and evoked spinal reflex responses (H-reflex evoked at rest and during weak isometric voluntary contraction) as well as twitch torques were analyzed. Caffeine increased MVT by 26.4 N m (95%CI: 9.3-43.5 N m, P = 0.004), 22.5 N m (95%CI: 3.1-42.0 N m, P = 0.025) and 22.5 N m (95%CI: 2.2-42.7 N m, P = 0.032) for isometric, concentric and eccentric contractions. Strength enhancements were associated with increases in voluntary activation. Explosive voluntary strength and voluntary activation at the onset of contraction were significantly increased following caffeine ingestion. Changes in spinal reflex responses and at the muscle level were not observed. Data suggest that caffeine ingestion induced an acute increase in voluntary activation that was responsible for the increased strength regardless of the contraction mode.

  13. Intramuscular pressure and electromyography as indexes of force during isokinetic exercise

    NASA Technical Reports Server (NTRS)

    Aratow, M.; Ballard, R. E.; Grenshaw, A. G.; Styf, J.; Watenpaugh, D. E.; Kahan, N. J.; Hargens, A. R.

    1993-01-01

    A direct method for measuring force production of specific muscles during dynamic exercise is presently unavailable. Previous studies indicate that both intramuscular pressure (IMP) and electromyography (EMG) correlate linearly with muscle contraction force during isometric exercise. The objective of this study was to compare IMP and EMG as linear assessors of muscle contraction force during dynamic exercise. IMP and surface EMG activity were recorded during concentric and eccentric isokinetic plantarflexion and dorsiflexion of the ankle joint from the tibialis anterior (TA) and soleus (SOL) muscles of nine male volunteers. Ankle torque was measured using a dynamometer, and IMP was measured via catheterization. IMP exhibited better linear correlation than EMG with ankle joint torque during concentric contractions of the SOL and the TA, as well as during eccentric contractions. IMP provides a better index of muscle contraction force than EMG during concentric and eccentric exercise through the entire range of torque. IMP reflects intrinsic mechanical properties of individual muscles, such as length-tension relationships, which EMG is unable to assess.

  14. Effects of exercise pressor reflex activation on carotid baroreflex function during exercise in humans

    NASA Technical Reports Server (NTRS)

    Gallagher, K. M.; Fadel, P. J.; Stromstad, M.; Ide, K.; Smith, S. A.; Querry, R. G.; Raven, P. B.; Secher, N. H.

    2001-01-01

    1. This investigation was designed to determine the contribution of the exercise pressor reflex to the resetting of the carotid baroreflex during exercise. 2. Ten subjects performed 3.5 min of static one-legged exercise (20 % maximal voluntary contraction) and 7 min dynamic cycling (20 % maximal oxygen uptake) under two conditions: control (no intervention) and with the application of medical anti-shock (MAS) trousers inflated to 100 mmHg (to activate the exercise pressor reflex). Carotid baroreflex function was determined at rest and during exercise using a rapid neck pressure/neck suction technique. 3. During exercise, the application of MAS trousers (MAS condition) increased mean arterial pressure (MAP), plasma noradrenaline concentration (dynamic exercise only) and perceived exertion (dynamic exercise only) when compared to control (P < 0.05). No effect of the MAS condition was evident at rest. The MAS condition had no effect on heart rate (HR), plasma lactate and adrenaline concentrations or oxygen uptake at rest and during exercise. The carotid baroreflex stimulus-response curve was reset upward on the response arm and rightward to a higher operating pressure by control exercise without alterations in gain. Activation of the exercise pressor reflex by MAS trousers further reset carotid baroreflex control of MAP, as indicated by the upward and rightward relocation of the curve. However, carotid baroreflex control of HR was only shifted rightward to higher operating pressures by MAS trousers. The sensitivity of the carotid baroreflex was unaltered by exercise pressor reflex activation. 4. These findings suggest that during dynamic and static exercise the exercise pressor reflex is capable of actively resetting carotid baroreflex control of mean arterial pressure; however, it would appear only to modulate carotid baroreflex control of heart rate.

  15. Effect of forced exercise and exercise withdrawal on memory, serum and hippocampal corticosterone levels in rats.

    PubMed

    Radahmadi, Maryam; Alaei, Hojjatallah; Sharifi, Mohammad Reza; Hosseini, Nasrin

    2015-10-01

    Evidence suggests that there are positive effects of exercise on learning and memory. Moreover, some studies have demonstrated that forced exercise plays the role of a stressor. This study was aimed at investigating the effects of different timing of exercise and exercise withdrawal on memory, and serum and hippocampal corticosterone (CORT) levels. Wistar rats were randomly divided into five groups: control, sham, exercise-rest (exercise withdrawal), rest-exercise (exercised group), and exercise-exercise (continuous exercise). Rats were forced to run on a treadmill for 1 h/day at a speed 20-21-m/min. Memory function was evaluated by the passive avoidance test in different intervals (1, 7 and 21 days) after foot shock. Findings showed that after the exercise withdrawal, short-term and mid-term memories, had significant enhancement compared to the control group, while the long-term memory did not present this result. In addition, the serum and hippocampal CORT levels were at the basal levels after the rest period in the exercise-rest group. In the rest-exercise group, exercise improved mid- and long-term memories, whereas continuous exercise improved all types short-, mid- and long-term memories, particularly the mid-term memory. Twenty-one and forty-two days of exercise significantly decreased the serum and hippocampal CORT levels. It seems that exercise for at least 21 days with no rest could affect biochemical factors in the brain. Also, regular continuous exercise plays an important role in memory function. Hence, the duration and withdraw of exercise are important factors for the neurobiological aspects of the memory responses.

  16. Sex differences in the effect of fish-oil supplementation on the adaptive response to resistance exercise training in older people: a randomized controlled trial.

    PubMed

    Da Boit, Mariasole; Sibson, Rachael; Sivasubramaniam, Selvaraj; Meakin, Judith R; Greig, Carolyn A; Aspden, Richard M; Thies, Frank; Jeromson, Stewart; Hamilton, D Lee; Speakman, John R; Hambly, Catherine; Mangoni, Arduino A; Preston, Thomas; Gray, Stuart R

    2017-01-01

    Resistance exercise increases muscle mass and function in older adults, but responses are attenuated compared with younger people. Data suggest that long-chain n-3 polyunsaturated fatty acids (PUFAs) may enhance adaptations to resistance exercise in older women. To our knowledge, this possibility has not been investigated in men. We sought to determine the effects of long-chain n-3 PUFA supplementation on resistance exercise training-induced increases in muscle mass and function and whether these effects differ between older men and women. Fifty men and women [men: n = 27, mean ± SD age: 70.6 ± 4.5 y, mean ± SD body mass index (BMI; in kg/m 2 ): 25.6 ± 4.2; women: n = 23, mean ± SD age: 70.7 ± 3.3 y, mean ± SD BMI: 25.3 ± 4.7] were randomly assigned to either long-chain n-3 PUFA (n = 23; 3 g fish oil/d) or placebo (n = 27; 3 g safflower oil/d) and participated in lower-limb resistance exercise training twice weekly for 18 wk. Muscle size, strength, and quality (strength per unit muscle area), functional abilities, and circulating metabolic and inflammatory markers were measured before and after the intervention. Maximal isometric torque increased after exercise training to a greater (P < 0.05) extent in the long-chain n-3 PUFA group than in the placebo group in women, with no differences (P > 0.05) between groups in men. In both sexes, the effect of exercise training on maximal isokinetic torque at 30, 90, and 240° s -1 , 4-m walk time, chair-rise time, muscle anatomic cross-sectional area, and muscle fat did not differ (P > 0.05) between groups. There was a greater (P < 0.05) increase in muscle quality in women after exercise training in the long-chain n-3 PUFA group than in the placebo group, with no such differences in men (P > 0.05). Long-chain n-3 PUFAs resulted in a greater decrease (P < 0.05) than the placebo in plasma triglyceride concentrations in both sexes, with no differences (P > 0.05) in glucose, insulin, or inflammatory markers. Long-chain n

  17. Neuromuscular function during knee extension exercise after cold water immersion.

    PubMed

    Wakabayashi, Hitoshi; Wijayanto, Titis; Tochihara, Yutaka

    2017-06-23

    Human adaptability to cold environment has been focused on in the physiological anthropology and related research area. Concerning the human acclimatization process in the natural climate, it is necessary to conduct a research assessing comprehensive effect of cold environment and physical activities in cold. This study investigated the effect of cold water immersion on the exercise performance and neuromuscular function during maximal and submaximal isometric knee extension. Nine healthy males participated in this study. They performed maximal and submaximal (20, 40, and 60% maximal load) isometric knee extension pre- and post-immersion in 23, 26, and 34 °C water. The muscle activity of the rectus femoris (RF) and vastus lateralis (VL) was measured using surface electromyography (EMG). The percentages of the maximum voluntary contraction (%MVC) and mean power frequency (MPF) of EMG data were analyzed. The post-immersion maximal force was significantly lower in 23 °C than in 26 and 34 °C conditions (P < 0.05). The post-immersion %MVC of RF was significantly higher than pre-immersion during 60% maximal exercise in 23 and 26 °C conditions (P < 0.05). In the VL, the post-immersion %MVC was significantly higher than pre-immersion in 23 and 26 °C conditions during 20% maximal exercise and in 26 °C at 40 and 60% maximal intensities (P < 0.05). The post-immersion %MVC of VL was significantly higher in 26 °C than in 34 °C at 20 and 60% maximal load (P < 0.05). The post-immersion MPF of RF during 20% maximal intensity was significantly lower in 23 °C than in 26 and 34 °C conditions (P < 0.05), and significantly different between three water temperature conditions at 40 and 60% maximal intensities (P < 0.05). The post-immersion MPF of VL during three submaximal trials were significantly lower in 23 and 26 °C than in 34 °C conditions (P < 0.05). The lower shift of EMG frequency would be connected with the decrease in the

  18. Effect of hand-arm exercise on venous blood constituents during leg exercise

    NASA Technical Reports Server (NTRS)

    Wong, N.; Silver, J. E.; Greenawalt, S.; Kravik, S. E.; Geelen, G.

    1985-01-01

    Contributions by ancillary hand and arm actions to the changes in blood constituents effected by leg exercises on cycle ergometer were assessed. Static or dynamic hand-arm exercises were added to the leg exercise (50 percent VO2 peak)-only control regimens for the subjects (19-27 yr old men) in the two experimental groups. Antecubital venous blood was analyzed at times 0, 15, and 30 min (T0, T15, and T30) for serum Na(+), K(+), osmolality, albumin, total CA(2+), and glucose; blood hemoglobin, hematocrit, and lactic acid; and change in plasma volume. Only glucose and lactate values were affected by additional arm exercise. Glucose decreased 4 percent at T15 and T30 after static exercise, and by 2 percent at T15 (with no change at T30) after dynamic arm exercise. Conversely, lactic acid increased by 20 percent at T30 after static exercise, and by 14 percent by T15 and 6 percent at T30 after dynamic arm exercise. It is concluded that additional arm movements, performed usually when gripping the handle-bar on the cycle ergometer, could introduce significant errors in measured venous concentrations of glucose and lactate in the leg-exercised subjects.

  19. EEG signatures of arm isometric exertions in preparation, planning and execution.

    PubMed

    Nasseroleslami, Bahman; Lakany, Heba; Conway, Bernard A

    2014-04-15

    The electroencephalographic (EEG) activity patterns in humans during motor behaviour provide insight into normal motor control processes and for diagnostic and rehabilitation applications. While the patterns preceding brisk voluntary movements, and especially movement execution, are well described, there are few EEG studies that address the cortical activation patterns seen in isometric exertions and their planning. In this paper, we report on time and time-frequency EEG signatures in experiments in normal subjects (n=8), using multichannel EEG during motor preparation, planning and execution of directional centre-out arm isometric exertions performed at the wrist in the horizontal plane, in response to instruction-delay visual cues. Our observations suggest that isometric force exertions are accompanied by transient and sustained event-related potentials (ERP) and event-related (de-)synchronisations (ERD/ERS), comparable to those of a movement task. Furthermore, the ERPs and ERD/ERS are also observed during preparation and planning of the isometric task. Comparison of ear-lobe-referenced and surface Laplacian ERPs indicates the contribution of superficial sources in supplementary and pre-motor (FC(z)), parietal (CP(z)) and primary motor cortical areas (C₁ and FC₁) to ERPs (primarily negative peaks in frontal and positive peaks in parietal areas), but contribution of deep sources to sustained time-domain potentials (negativity in planning and positivity in execution). Transient and sustained ERD patterns in μ and β frequency bands of ear-lobe-referenced and surface Laplacian EEG indicate the contribution of both superficial and deep sources to ERD/ERS. As no physical displacement happens during the task, we can infer that the underlying mechanisms of motor-related ERPs and ERD/ERS patterns do not only depend on change in limb coordinate or muscle-length-dependent ascending sensory information and are primary generated by motor preparation, direction

  20. Muscle metaboreceptor modulation of cutaneous active vasodilation

    NASA Technical Reports Server (NTRS)

    Crandall, C. G.; Stephens, D. P.; Johnson, J. M.

    1998-01-01

    PURPOSE: Isometric handgrip exercise in hyperthermia has been shown to reduce cutaneous vascular conductance (CVC) by inhibiting the cutaneous active vasodilator system. METHODS: To identify whether this response was initiated by muscle metaboreceptors, in seven subjects two 3-min bouts of isometric handgrip exercise in hyperthermia were performed, followed by 2 min of postexercise ischemia (PEI). An index of forearm skin blood flow (laser-Doppler flowmetry) was measured on the contralateral arm at an unblocked site and at a site at which adrenergic vasoconstrictor function was blocked via bretylium iontophoresis to reveal active cutaneous vasodilator function unambiguously. Sweat rate was measured via capacitance hygrometry, CVC was indexed from the ratio of skin blood flow to mean arterial pressure and was expressed as a percentage of maximal CVC at that site. In normothermia, neither isometric exercise nor PEI affected CVC (P > 0.05). RESULTS: The first bout of isometric handgrip exercise in hyperthermia reduced CVC at control sites and this reduction persisted through PEI (pre-exercise: 59.8 +/- 5.4, exercise: 49.8 +/- 4.9, PEI: 49.7 +/- 5.3% of maximum; both P < 0.05), whereas there were no significant changes in CVC at the bretylium treated sites. The succeeding bout of isometric exercise in hyperthermia significantly reduced CVC at both untreated (pre-exercise: 59.0 +/- 4.8, exercise: 47.3 +/- 4.0, PEI: 50.1 +/- 4.1% of maximum; both P < 0.05) and bretylium treated sites (pre-exercise: 61.4 +/- 7.3, exercise: 50.6 +/- 5.1, PEI: 53.9 +/- 6.0% of maximum, both P < 0.05). At both sites, CVC during PEI was lower than during the pre-exercise period (P < 0.05). Sweat rate rose significantly during both bouts of isometric exercise and remained elevated during PEI. CONCLUSIONS: These data suggest that the reduction in CVC during isometric exercise in hyperthermia, including the inhibition of the active vasodilator system, is primarily mediated by muscle

  1. Does the addition of hip strengthening exercises improve outcomes following total knee arthroplasty? A study protocol for a randomized trial.

    PubMed

    Schache, Margaret B; McClelland, Jodie A; Webster, Kate E

    2016-06-13

    Total knee arthroplasty (TKA) is effective in reducing pain and improving function for end-stage knee osteoarthritis. However, muscle weakness and functional limitations persist despite assistance from post-operative rehabilitation programs that traditionally focus on quadriceps strengthening and range of movement exercises. Hip abductor muscle weakness is evident in knee osteoarthritis and hip muscle strengthening reduces knee pain in this group. Following TKA, people with weak hip abductor strength perform more poorly on measures of physical function. However, very little is known of the effectiveness of including hip abductor strengthening exercises in post-operative rehabilitation. The aim of this trial is to compare the effects of targeted hip abductor strengthening to those of traditional care in a TKA rehabilitation program on muscle strength, patient reported outcomes and functional performance measures. This protocol describes a single-blinded randomized controlled trial, where 104 participants referred for inpatient rehabilitation following TKA will be recruited. Participants will be randomized using computer-generated numbers to one of two groups: usual care or usual care with additional hip strengthening exercises. Participants will attend physiotherapy daily during their inpatient length of stay, and will then attend between six and eight physiotherapy sessions as an outpatient. Primary outcomes are isometric hip abductor strength and the Knee Injury and Osteoarthritis Outcome Score (KOOS). Secondary outcomes are stair climb test, 6 min walk test, timed up and go, 40 m fast-paced walk test, 30 second chair stand test, isometric quadriceps strength, Lower Extremity Functional Scale (LEFS) and SF-12. Outcome measures will be recorded at baseline (admission to inpatient rehabilitation), and then 3 weeks, 6 weeks and 6 months post admission to rehabilitation. The findings of this study will determine whether the addition of targeted hip strengthening

  2. Neuromuscular and muscle-tendon system adaptations to isotonic and isokinetic eccentric exercise.

    PubMed

    Guilhem, G; Cornu, C; Guével, A

    2010-06-01

    To present the properties of an eccentric contraction and compare neuromuscular and muscle-tendon system adaptations induced by isotonic and isokinetic eccentric trainings. An eccentric muscle contraction is characterized by the production of muscle force associated to a lengthening of the muscle-tendon system. This muscle solicitation can cause micro lesions followed by a regeneration process of the muscle-tendon system. Eccentric exercise is commonly used in functional rehabilitation for its positive effect on collagen synthesis but also for resistance training to increase muscle strength and muscle mass in athletes. Indeed, eccentric training stimulates muscle hypertrophy, increases the fascicle pennation angle, fascicles length and neural activation, thus inducing greater strength gains than concentric or isometric training programs. Eccentric exercise is commonly performed either against a constant external load (isotonic) or at constant velocity (isokinetic), inducing different mechanical constraints. These different mechanical constraints could induce structural and neural adaptive strategies specific to each type of exercise. The literature tends to show that isotonic mode leads to a greater strength gain than isokinetic mode. This observation could be explained by a greater neuromuscular activation after IT training. However, the specific muscle adaptations induced by each mode remain difficult to determine due to the lack of standardized, comparative studies. 2010 Elsevier Masson SAS. All rights reserved.

  3. Pre-exercise β-hydroxy-β-methylbutyrate free-acid supplementation improves work capacity recovery: a randomized, double-blinded, placebo-controlled study.

    PubMed

    Correia, Ana Luiza Matias; de Lima, Filipe Dinato; Bottaro, Martim; Vieira, Amilton; da Fonseca, Andrew Correa; Lima, Ricardo M

    2018-02-08

    The purpose of this study was to investigate the effects of a single-dose of β-hydroxy-β-methylbutyrate free acid (HMB-FA) supplementation on muscle recovery after a high-intensity exercise bout. Twenty-three trained young males were randomly assigned to receive either a single-dose supplementation of 3g of HMB-FA (n = 12; age 22.8 ± 3.0 years) or placebo (PLA; n = 11; age 22.9 ± 3.1 years). A muscle damage protocol was applied 60 minutes after supplementation, and consisted of seven sets of 20 drop jumps from a 60-cm box with 2-min rest intervals between sets. Muscle swelling, countermovement jump (CMJ), maximal voluntary isometric torque (MVIT) and work capacity (WC) were measured before, immediately after, 24, 48 and 72 hours after the exercise protocol. Muscle swelling, CMJ and MVIT changed similarly in both groups after the exercise protocol (p < 0.001), but returned to pre-exercise levels after 24 hours in both groups. WC decreased similarly in both groups after the exercise protocol (p < 0.01). For HMB-FA, WC returned to pre-exercise level 24 hours after exercise protocol. However, on PLA, WC did not return to pre-exercise level even 72 hours after the exercise protocol. In summary, a single-dose of HMB-FA supplementation improved WC recovery after a high-intensity exercise bout. However, HMB-FA did not affect the time-course of muscle swelling, MVIT and CMJ recovery.

  4. Effect of local cooling on short-term, intense exercise.

    PubMed

    Kwon, Young S; Robergs, Robert A; Schneider, Suzanne M

    2013-07-01

    The widespread belief that local cooling impairs short-term, strenuous exercise performance is controversial. Eighteen original investigations involving cooling before and intermittent cooling during short-term, intensive exercise are summarized in this review. Previous literature examining short-term intensive exercise and local cooling primarily has been limited to the effects on muscle performance immediately or within minutes following cold application. Most previous cooling studies used equal and longer than 10 minutes of pre-cooling, and found that cooling reduced strength, performance and endurance. Because short duration, high intensity exercise requires adequate warm-up to prepare for optimal performance, prolonged pre-cooling is not an effective method to prepare for this type of exercise. The literature related to the effect of acute local cooling immediately before short duration, high intensity isotonic exercise such as weight lifting is limited. However, local intermittent cooling during short-term, high intense exercise may provide possible beneficial effects; first, by pain reduction, caused by an "irritation effect" from hand thermal receptors which block pain sensation, or second, by a cooling effect, whereby stimulation of hand thermal receptors or a slight lowering of blood temperature might alter central fatigue.

  5. Electromyographic Activity of Scapular Muscle Control in Free-Motion Exercise

    PubMed Central

    Nakamura, Yukiko; Tsuruike, Masaaki; Ellenbecker, Todd S.

    2016-01-01

    Context:  The appropriate resistance intensity to prescribe for shoulder rehabilitative exercise is not completely known. Excessive activation of the deltoid and upper trapezius muscles could be counterproductive for scapulohumeral rhythm during humeral elevation. Objective:  To identify the effects of different exercise intensities on the scapular muscles during a free-motion “robbery” exercise performed in different degrees of shoulder abduction in seated and standing positions. Design:  Descriptive laboratory study. Setting:  Kinesiology Adapted Physical Education Laboratory. Patients or Other Participants:  A total of 15 healthy male college students (age = 20.5 ± 2.2 years, height = 174.5 ± 5.3 cm, mass = 63.8 ± 6.0 kg). Intervention(s):  Participants performed 5 repetitions of a randomized exercise sequence of the robbery exercise in 2 body positions (seated, standing), 2 shoulder-abducted positions (W [20°], 90/90 [90°]) at 3 intensities (0%, 3%, and 7% body weight). Main Outcome Measure(s):  Electromyographic (EMG) activity of the upper trapezius, lower trapezius, serratus anterior, anterior deltoid, and infraspinatus muscles of the upper extremity was collected. All EMG activities were normalized by the maximal voluntary isometric contraction of each corresponding muscle (%). Results:  The serratus anterior, anterior deltoid, and infraspinatus EMG activities were greater at 7% body weight in the seated position compared with the standing position (P < .05). The EMG activities in all 5 muscles were greater in the 90/90 position than in the W position (P < .05). Conclusions:  Scapular muscle activity modulated relative to changes in body posture and resistance intensity. These findings will enable clinicians to prescribe the appropriate level of exercise intensity and positioning during shoulder rehabilitation. PMID:26986055

  6. Acute effect of oral water intake during exercise on post-exercise hypotension.

    PubMed

    Endo, M Y; Kajimoto, C; Yamada, M; Miura, A; Hayashi, N; Koga, S; Fukuba, Y

    2012-11-01

    Post-exercise hypotension (PEH) is a sustained reduction in mean arterial blood pressure (MAP) after prolonged exercise. As water drinking is known to elicit a large acute pressor response, we aimed to explore the effect of drinking water during exercise on PEH. Ten normotensive male volunteers performed the control protocol: 30 min supine rest, 60 min cycling exercise in moderate intensity, and 60 min supine rest recovery. In the water drinking protocol, the same procedure was followed but with water intake during exercise to compensate for exercise-induced body weight lost. Heart rate, MAP, cardiac output and blood flow in the brachial artery were measured pre- and post-exercise. The total vascular conductance (TVC) and the vascular conductance (VC) in the brachial artery were calculated pre- and post-exercise, and the relative change in plasma volume (ΔPV) was also measured. Body weight loss during exercise was 0.65 ± 0.24 kg in the control. ΔPV was not different during recovery in either protocol. MAP in the control was significantly reduced during the latter half of the recovery compared with baseline. In contrast, MAP in the water drinking showed no reduction during recovery, and was significantly higher than in the control. TVC and VC in the brachial artery were lower in the water drinking, in which vasoconstriction was relatively exaggerated. Prevention of dehydration after exercise by oral water intake, or oral water intake per se has a role in maintaining post-exercise MAP and it may be related to reduction in TVC.

  7. Effectiveness of a home-based strength