Maximal isometric force and neural activity during bilateral and unilateral elbow flexion in humans

1994 ◽  
Vol 69 (3) ◽  
pp. 240-243 ◽  
Author(s):  
Shingo Oda ◽  
Toshio Moritani
Keyword(s):  
Neural Activity ◽  
Isometric Force ◽  
Elbow Flexion ◽  
Maximal Isometric Force

Maximal Voluntary Isometric Elbow Flexion Force during Unilateral versus Bilateral Contractions in Individuals with Chronic Stroke

2008 ◽  
Vol 24 (1) ◽  
pp. 69-74 ◽  
Author(s):  
Kevin McQuade ◽  
Michelle L. Harris-Love ◽  
Jill Whitall
Keyword(s):  
Isometric Force ◽  
Force Production ◽  
Elbow Flexion ◽  
Chronic Stroke ◽  
Total Force ◽  
Elbow Flexors ◽  
Task Conditions ◽  
Isometric Force Production ◽  
Flexion Force ◽  
Maximal Isometric Force

The purpose of this study was to determine whether the phenomenon of bilateral deficit in muscular force production observed in healthy subjects and mildly impaired stroke patients also exists in patients with more chronic and greater levels of stroke impairment. Ten patients with chronic hemiparesis resulting from stroke performed unilateral and bilateral maximal voluntary isometric contractions of the elbow flexors. When the total force produced by both arms was compared, 12% less force was produced in the bilateral compared with unilateral condition (p= 0.01). However, studying the effect of task conditions on each arm separately revealed a significant decline in nonparetic (p= 0.01) but not paretic elbow flexor force in the bilateral compared with unilateral condition. Results suggest that a significant bilateral force deficit exists in the nonparetic but not the paretic arm in individuals with chronic stroke. Bilateral task conditions do not seem to benefit or impair paretic arm maximal isometric force production in individuals with moderate-severity chronic stroke.

The Effect of Training Volume on the Acute Response and Adaptations to Resistance Training

2006 ◽  
Vol 1 (2) ◽  
pp. 108-121 ◽  
Author(s):  
Jason Brandenburg ◽  
David Docherty
Keyword(s):  
Resistance Exercise ◽  
Blood Lactate ◽  
Isometric Force ◽  
Elbow Flexion ◽  
Constant Load ◽  
Single Session ◽  
Threshold Response ◽  
Acute Response ◽  
Before And After ◽  
Maximal Isometric Force

Purpose:To examine the acute response to 2 resistance-exercise protocols performed to repetition failure, but different in load configuration, and determine whether the acute response was related to strength increases after 8 weeks of training.Methods:Eighteen resistance-trained men completed a single session of 2 resistance-exercise protocols. The constant-load protocol (CL) required subjects to complete 3 sets of single-arm preacher curls (elbow flexion) to failure using a load of ~77% 1RM. The reduced-load protocol (RL) was similar, but training load was reduced for the second and third sets. Maximal isometric force (MVIC) and blood lactate were assessed preprotocol and postprotocol to determine the acute response. For the 8-week training phase, subjects (N = 12) were divided into 2 programs, each corresponsing to 1 of the protocols. Strength was measured before and after training.Results:MVIC decreased from 106.2 ± 13.8 to 84.3 ± 12.1 N · m and from 109.1 ± 14.7 to 82.5 ± 13 N · m after the CL and RL protocols, respectively. The decrements in MVIC were significant (P < .001), with the decline after RL tending to be greater (P = .051). Postprotocol blood lactate concentrations after CL and RL were 3.4 ± 1.1 and 4.1 ± 1.3 mmol/L, respectively, with greater increases after RL (P = .036). Similar and significant 1RM strength increases were observed after both programs (from 20.7 ± 2.7 to 23.3 ± 3.5 kg after CL and from 22.4 ± 2.9 to 25.5 ± 3.2 kg after RL; P < .001).Conclusion:The similar increases in strength suggest that either the greater acute response to RL was not related to the increases in strength or a minimal (threshold) response was achieved during both programs.

Acute Physiological Response to Light- and Heavy-load Power-oriented Exercise in Older Adults

2021 ◽  
Author(s):  
Carlos Rodriguez-Lopez ◽  
Julian Alcazar ◽  
Jose Losa-Reyna ◽  
JuanManuel Carmona-Torres ◽  
Aurora Maria Cruz-Santaella ◽  
...  
Keyword(s):  
Older Adults ◽  
Creatine Kinase ◽  
Resistance Training ◽  
Isometric Force ◽  
Rate Of Force Development ◽  
Heavy Load ◽  
Force Development ◽  
Sit To Stand ◽  
Light Load ◽  
Maximal Isometric Force

AbstractThis study investigated the acute responses to volume-load-matched heavy-load (80% 1RM) versus light-load (40% 1RM) power-oriented resistance training sessions in well-functioning older adults. Using a randomized cross-over design, 15 volunteers completed each condition on a leg press. Neuromuscular (maximal isometric force and rate of force development) and functional performance (power during sit-to-stand test), lactate, and muscle damage biochemistry (creatine kinase, lactate dehydrogenase and C-reactive protein serum concentration) were assessed pre- and post-exercise. Performance declines were found after heavy-load (Cohen’s d effect size (d); maximal isometric force=0.95 d; rate of force development=1.17 d; sit-to-stand power =0.38 d, all p<0.05) and light-load (maximal isometric force=0.45 d; rate of force development=0.9 d; sit-to-stand power=1.17 d, all p<0.05), while lactate concentration increased only after light-load (1.7 d, p=0.001). However, no differences were found between conditions (all p>0.05). Both conditions increased creatine kinase the day after exercise (marginal effect=0.75 d, p<0.001), but no other blood markers increased (all, p>0.05). Irrespective of the load used, power training induced non-clinically significant decreases in sit-to-stand performance, moderate declines in maximal isometric force, but pronounced decreases in the rate of force development. Furthermore, the metabolic stress and muscle damage were minor; both sessions were generally well tolerated by well-functioning older adults without previous experience in resistance training.

Reliability and Validity of a Novel Trunk-Strength Assessment for High-Performance Sprint Flat-Water Kayakers

2019 ◽  
Vol 14 (4) ◽  
pp. 486-492
Author(s):  
Darren Steeves ◽  
Leo J. Thornley ◽  
Joshua A. Goreham ◽  
Matthew J. Jordan ◽  
Scott C. Landry ◽  
...  
Keyword(s):  
High Performance ◽  
Isometric Force ◽  
Reliability And Validity ◽  
Small Degree ◽  
Strong Correlations ◽  
Strength Assessment ◽  
Performance Times ◽  
Voluntary Contractions ◽  
Pearson Correlations ◽  
Maximal Isometric Force

Purpose: To determine the reliability and validity of a novel trunk maximal isometric force assessment involving 7 different tasks with 200-m times for elite sprint flat-water kayakers. Methods: Ten elite sprint flat-water kayakers performed a series of maximal isometric voluntary contractions (MVCs) on 2 separate days to assess reliability. MVC force was assessed as the participants sat on a modified kayak ergometer and applied their maximal isometric force to a uniaxial load cell during 7 different tasks. The 7 tasks of interest were a seated trunk-forward flexion, bilateral (left and right) rotational pulls, bilateral rotational pushes, and a sport-specific bilateral kayak-stroke simulation. Twenty elite flat-water kayak athletes (10 male and 10 female) participated in the validity portion by completing the series of tasks in conjunction with a 200-m race. Results: MVC force values ranged from 84 to 800 N across all participants and all tasks. The average coefficient of variation of the 7 tasks ranged from 2.4% to 7.7%. Regression analysis showed Pearson correlations ranging from −.84 to −.22 for both absolute and relative values with 200-m performance times. Conclusions: MVC force measured in each task was considered reliable as a small degree of variance between trials was found. The summation of the 7 trunk scores showed very strong correlations with on-water performance, indicating that this assessment is valid for elite sprint kayakers.

scholarly journals Maximal isometric force exertion predicted by the force feasible set formalism: application to handbraking

Ergonomics ◽  
2019 ◽  
Vol 62 (12) ◽  
pp. 1551-1562
Author(s):  
Nasser Rezzoug ◽  
Xuguang Wang ◽  
Vincent Hernandez ◽  
Philippe Gorce
Keyword(s):  
Isometric Force ◽  
Feasible Set ◽  
Maximal Isometric Force

scholarly journals Fatty Infiltration Is a Prognostic Marker of Muscle Function After Rotator Cuff Tear

2018 ◽  
Vol 46 (9) ◽  
pp. 2161-2169 ◽  
Author(s):  
Ana P. Valencia ◽  
Jim K. Lai ◽  
Shama R. Iyer ◽  
Katherine L. Mistretta ◽  
Espen E. Spangenburg ◽  
...  
Keyword(s):  
Rotator Cuff ◽  
Muscle Atrophy ◽  
Muscle Function ◽  
Contractile Function ◽  
Isometric Force ◽  
Fatty Infiltration ◽  
Collagen Content ◽  
Strongly Correlated ◽  
Computed Tomography Scanning ◽  
Maximal Isometric Force

Background: Massive rotator cuff tears (RCTs) begin as primary tendon injuries and cause a myriad of changes in the muscle, including atrophy, fatty infiltration (FI), and fibrosis. However, it is unclear which changes are most closely associated with muscle function. Purpose: To determine if FI of the supraspinatus muscle after acute RCT relates to short-term changes in muscle function. Study Design: Controlled laboratory study. Methods: Unilateral RCTs were induced in female rabbits via tenotomy of the supraspinatus and infraspinatus. Maximal isometric force and rate of fatigue were measured in the supraspinatus in vivo at 6 and 12 weeks after tenotomy. Computed tomography scanning was performed, followed by histologic analysis of myofiber size, FI, and fibrosis. Results: Tenotomy resulted in supraspinatus weakness, reduced myofiber size, FI, and fibrosis, but no differences were evident between 6 and 12 weeks after tenotomy except for increased collagen content at 12 weeks. FI was a predictor of supraspinatus weakness and was strongly correlated to force, even after accounting for muscle cross-sectional area. While muscle atrophy accounted for the loss in force in tenotomized muscles with minimal FI, it did not account for the greater loss in force in tenotomized muscles with the most FI. Collagen content was not strongly correlated with maximal isometric force, even when normalized to muscle size. Conclusion: After RCT, muscle atrophy results in the loss of contractile force from the supraspinatus, but exacerbated weakness is observed with increased FI. Therefore, the level of FI can help predict contractile function of torn rotator cuff muscles. Clinical Relevance: Markers to predict contractile function of RCTs will help determine the appropriate treatment to improve functional recovery after RCTs.

scholarly journals Influenza Infection has Fiber Type-Specific Effects on Cellular and Molecular Skeletal Muscle Function in Aged Mice

2020 ◽  
Vol 75 (12) ◽  
pp. 2333-2341
Author(s):  
Chad R Straight ◽  
Olivia R Ringham ◽  
Jenna M Bartley ◽  
Spencer R Keilich ◽  
George A Kuchel ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Contractile Function ◽  
Isometric Force ◽  
Fiber Type ◽  
Influenza Infection ◽  
Fiber Types ◽  
Specific Force ◽  
Mhc Iia ◽  
Mhc Iib ◽  
Maximal Isometric Force

Abstract Skeletal muscle myopathies represent a common non-pulmonary manifestation of influenza infection, leading to reduced physical function and hospitalization in older adults. However, underlying mechanisms remain poorly understood. Our study examined the effects of influenza virus A pulmonary infection on contractile function at the cellular (single fiber) and molecular (myosin-actin interactions and myofilament properties) levels in soleus and extensor digitorum longus muscles of aged (20 months) C57BL/6 male mice that were healthy or flu-infected for 7 (7-days post-infection; 7-DPI) or 12 days (12-DPI). Cross-sectional area (CSA) of myosin heavy chain (MHC) IIA and IIB fibers was reduced at 12-DPI relative to 7-DPI and healthy. Maximal isometric force in MHC IIA fibers was also reduced at 12-DPI relative to 7-DPI and healthy, resulting in no change in specific force (maximal isometric force divided by CSA). In contrast, MHC IIB fibers produced greater isometric force and specific force at 7-DPI compared to 12-DPI or healthy. The increased specific force in MHC IIB fibers was likely due to greater myofilament lattice stiffness and/or an increased number or stiffness of strongly bound myosin-actin cross-bridges. At the molecular level, cross-bridge kinetics were slower in MHC IIA fibers with infection, while changes in MHC IIB fibers were largely absent. In both fiber types, greater myofilament lattice stiffness was positively related to specific force. This study provides novel evidence that cellular and molecular contractile function is impacted by influenza infection in a fiber type-specific manner, suggesting potential molecular mechanisms to help explain the impact of flu-induced myopathies.

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