Divergent muscle fatigue during unilateral isometric contractions of dominant and non-dominant quadriceps

2013 ◽  
Vol 16 (3) ◽  
pp. 240-244 ◽  
Author(s):  
Mark E.T. Willems ◽  
James P.G. Ponte
Keyword(s):  
Muscle Fatigue ◽  
Isometric Contractions

sEMG feature analysis on forearm muscle fatigue during isometric contractions

2014 ◽  
Vol 20 (2) ◽  
pp. 139-143 ◽  
Author(s):  
Dong Ming ◽  
Xin Wang ◽  
Rui Xu ◽  
Shuang Qiu ◽  
Xin Zhao ◽  
...  
Keyword(s):  
Muscle Fatigue ◽  
Feature Analysis ◽  
Isometric Contractions ◽  
Forearm Muscle

scholarly journals Contraction frequency modulates muscle fatigue and the rate of myoglobin desaturation during incremental contractions in humans

2008 ◽  
Vol 33 (5) ◽  
pp. 915-921 ◽  
Author(s):  
Danielle M. Wigmore ◽  
Douglas E. Befroy ◽  
Ian R. Lanza ◽  
Jane A. Kent-Braun
Keyword(s):  
Muscle Fatigue ◽  
Muscle Force ◽  
Force Production ◽  
Metabolic Cost ◽  
Resonance Spectroscopy ◽  
Isometric Contractions ◽  
Metabolic Demand ◽  
Contraction Frequency ◽  
Duty Cycles ◽  
Force Time

The metabolic cost of force production, and therefore the demand for oxygen, increases with intensity and frequency of contraction. This study investigated the interaction between fatigue and oxygenation, as reflected by deoxymyoglobin (dMb), during slow and rapid rhythmic isometric contractions having the same duty cycles and relative force–time integrals (FTIs). We used 1H magnetic resonance spectroscopy and measures of dorsiflexor muscle force to compare dMb and fatigue (fall of maximal voluntary force, MVC) in 11 healthy adults (29 ± 7 y) during 16 min of slow (4 s contraction, 6 s relaxation) and rapid (1.2 s, 1.8 s) incremental (10%–80% MVC) contractions. We tested the hypotheses that (i) the rate of Mb desaturation would be faster in rapid than in slow contractions and (ii) fatigue, Mb desaturation, and the fall in FTI would be greater, and PO2 (oxygen tension) lower, at the end of rapid contractions than at the end of slow contractions. Although dMb increased more quickly during rapid contractions (p = 0.05), it reached a plateau at a similar level in both protocols (~42% max, p = 0.49), likely due to an inability to further increase force production and thus metabolic demand. Despite the similar dMb at the end of both protocols, fatigue was greater in rapid (56.6% ± 2.7% baseline) than in slow (69.5% ± 4.0%, p = 0.01) contractions. These results indicate that human skeletal muscle fatigue during incremental isometric contractions is in part a function of contraction frequency, possibly due to metabolic inhibition of the contractile process.

Nonlinear Control of NMES: Incorporating Fatigue and Calcium Dynamics

2009 ◽  
Author(s):  
N. Sharma ◽  
P. M. Patre ◽  
C. M. Gregory ◽  
W. E. Dixon
Keyword(s):  
Muscle Fatigue ◽  
Neuromuscular Electrical Stimulation ◽  
Isometric Contractions ◽  
Calcium Dynamics ◽  
Nonlinear Controller ◽  
Promising Technique ◽  
Current Effort ◽  
Model Mismatch ◽  
Fatigue Model ◽  
Femoris Muscle

Neuromuscular electrical stimulation (NMES) is a promising technique that has the potential to restore functional tasks in persons with movement disorders. Clinical and commercial NMES products exist for this purpose, but a pervasive problem with current technology is that overstimulation of the muscle (among other factors) leads to muscle fatigue. The objective of the current effort is to develop a NMES controller that incorporates the effects of muscle fatigue through an uncertain function of the calcium dynamics. A neural network-based estimate of the fatigue model mismatch is incorporated in a nonlinear controller through a backstepping based method to control the human quadriceps femoris muscle undergoing non-isometric contractions. The developed controller is proven to yield uniformly ultimately bounded stability for an uncertain nonlinear muscle model in the presence of bounded nonlinear disturbances (e.g., spasticity, delays, changing load dynamics).

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