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

New Pistol Grip Control for an Electric Utility Aerial Bucket Reduces Risk of Forearm Muscle Fatigue

2018 ◽  
Vol 62 (1) ◽  
pp. 888-892
Author(s):  
Richard W. Marklin ◽  
Jonathon E. Slightam ◽  
Mark L. Nagurka ◽  
Casey D. Garces ◽  
Lovely Krishen ◽  
...  
Keyword(s):  
Muscle Fatigue ◽  
Muscular Activity ◽  
Electric Utility ◽  
Scale Model ◽  
Overhead Line ◽  
Endurance Time ◽  
Forearm Muscles ◽  
Actual Equipment ◽  
Forearm Muscle ◽  
Semg Activity

Overhead line workers have anecdotally reported elevated levels of fatigue in forearm muscles when operating the pistol grip control that maneuvers an aerial bucket on a utility truck. Previous research with surface electromyographic (sEMG) recordings of forearm muscles corroborated these reports of muscle fatigue. A new pistol grip was designed that reduces the applied force by 50% in all directions of movement. In laboratory testing, sEMG signals were recorded from the upper extremity muscles of twenty subjects, who operated a conventional-force pistol grip and the 50% reduced-force control to move a 1/15 scale model of an aerial truck boom. The muscle that resulted in the greatest sEMG activity (extensor digitorum communis (EDC)) was the muscle that workers typically pointed to when they reported forearm muscle fatigue from using the control. The reduced-forced pistol grip decreased EDC sEMG by an average of 5.6%, compared to the conventional control, increasing the maximum endurance time by 38% according to muscle fatigue models. This study was the first to quantify muscular activity of a new aerial bucket pistol grip control and the results show promise for improving the occupational health of electric utility overhead line workers, specifically reducing muscle fatigue. Before the new design of the pistol grip can be commercialized, it must be tested in the field on actual equipment.

Effects of Handle Angle and Work Orientation on Hammering: II. Muscle Fatigue and Subjective Ratings of Body Discomfort

1989 ◽  
Vol 31 (4) ◽  
pp. 413-420 ◽  
Author(s):  
Richard W. Schoenmarklin ◽  
William S. Marras
Keyword(s):  
Muscle Fatigue ◽  
Work Orientation ◽  
Subjective Ratings ◽  
Ulnar Deviation ◽  
Companion Article ◽  
Body Discomfort ◽  
Forearm Muscle

This research investigated how changes in hammer handle angle and hammering orientation affected muscle fatigue in the forearm and subjective ratings of body discomfort. Forearm muscle fatigue and discomfort ratings were not significantly affected by handle angle, but they were significantly higher in the wall hammering orientation than in the bench orientation. The research in this article and in the companion article (Part I) reveal that for novices, hammers with handles angled in the range of 20-40 deg are advantageous because (1) they reduce ulnar deviation and may possibly decrease the incidence of hand/wrist disorders, and (2) they do not significantly affect hammering performance in the bench conditions, forearm muscle fatigue, or subjective ratings of body discomfort.

Effects of String Stiffness on Muscle Fatigue After a Simulated Tennis Match

2014 ◽  
Vol 30 (3) ◽  
pp. 401-406 ◽  
Author(s):  
Jean Bernard Fabre ◽  
Vincent Martin ◽  
Gil Borelli ◽  
Jean Theurel ◽  
Laurent Grélot
Keyword(s):  
Resonant Frequency ◽  
Muscle Fatigue ◽  
Ball Speed ◽  
Tennis Players ◽  
High Stiffness ◽  
Fatigue Development ◽  
Low Stiffness ◽  
Exercise Muscle ◽  
Forearm Muscle ◽  
Tennis Match

We tested the influence of string stiffness on the occurrence of forearm muscle fatigue during a tennis match. Sixteen tennis players performed two prolonged simulated tennis matches with low-stiffness or high-stiffness string. Before and immediately after exercise, muscle fatigability was evaluated on the forearm muscles during a maximal intermittent gripping task. Groundstroke ball speeds and the profile of acceleration of the racquet frame at collision were recorded during each match. The peak-to-peak amplitude of acceleration and the resonant frequency of the frame were significantly greater with high- (5060 ± 1892 m/s2and 204 ± 29 Hz, respectively) than with low-stiffness string (4704 ± 1671 m/s2and 191 ± 16 Hz, respectively). The maximal and the averaged gripping forces developed during the gripping task were significantly reduced after the tennis match with high- (−15 ± 14%, and −22 ± 14%, respectively), but not with low-stiffness string. The decrease of ball speed during the simulated matches tended to be greater with high- than with low-stiffness string (P= .06). Hence, playing tennis with high-stiffness string promotes forearm muscle fatigue development, which could partly contribute to the groundstroke ball speed decrement during the game.

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.

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