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Diminished fatigue at reduced muscle length in human skeletal muscle
Author(s) -
Lee Samuel C. K.,
Braim Anthony,
Becker Cara N.,
Prosser Laura A.,
Tokay Ann M.,
BinderMacleod Stuart A.
Publication year - 2007
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.20873
Subject(s) - muscle fatigue , muscle contraction , skeletal muscle , contraction (grammar) , muscular fatigue , electromyography , stimulation , medicine , materials science , physical medicine and rehabilitation
Understanding muscle fatigue properties at different muscle lengths is essential to improve electrical stimulation applications in which impaired muscle is activated to produce function or to serve as an orthotic assist. This study examined the effects of muscle length on fatigue in human quadriceps muscle. Twelve healthy subjects were tested at short and long muscle lengths (15° and 90° of knee flexion, respectively) before and after a fatigue‐producing protocol using low‐, high‐, and variable‐frequency testing trains. Greater fatigue was observed at the longer muscle length, supporting the notion that fatigue is largely dependent upon metabolic factors. Fatigue, however, was characterized by greater attenuation of low‐ than high‐frequency responses (i.e., low‐frequency fatigue, LFF) at the long length. This observation, accompanied by the fact that variable‐frequency trains produced greater augmentations in force production than comparable low‐frequency trains at the longer length, suggests that excitation–contraction coupling impairment is also a contributing factor to fatigue and plays a greater role at the more fatigue‐susceptible longer muscle length. Muscle Nerve, 2007