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Comparison of potentiated and unpotentiated twitches as an index of muscle fatigue
Author(s) -
Kufel Thomas J.,
Pineda Lilibeth A.,
Mador M. Jeffery
Publication year - 2002
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.10047
Subject(s) - muscle fatigue , medicine , contraction (grammar) , quadriceps muscle , muscle contraction , femoral nerve , fast twitch muscle , stimulation , chemistry , cardiology , endocrinology , electromyography , anesthesia , physical medicine and rehabilitation , skeletal muscle
Recent data suggest that the potentiated twitch is a more sensitive index of contractile fatigue than is the unpotentiated twitch. We hypothesized that after a potentially fatiguing load, the fall in twitch amplitude of the potentiated twitch would be significantly greater than that of an unpotentiated twitch. We compared the response of the potentiated and unpotentiated twitches to a series of potentially fatiguing loads using magnetic stimulation of the femoral nerve in 10 healthy subjects. The baseline unpotentiated quadriceps twitch force (TwQu), potentiated quadriceps twitch force (TwQp), and maximal voluntary contraction (MVC) were 129 ± 6 N, 198 ± 6 N, and 622 ± 25 N, respectively. During a fatigue protocol that was designed to induce a spectrum of fatigue from mild to marked, the percent fall in quadriceps twitch force was significantly greater for the potentiated method than for the unpotentiated method at all levels of fatigue ( P < .005). The within‐subject within‐day coefficient of variation was 7.5 ± 0.5% for TwQu and 5.6 ± 0.9% for TwQp. Thus, TwQp is reproducible and is superior to TwQu for detecting early muscle fatigue. © 2002 Wiley Periodicals, Inc. Muscle Nerve 25: 000–000, 2002