TY - JOUR
T1 - Effects of stimulation frequency versus pulse duration modulation on muscle fatigue
AU - Kesar, Trisha
AU - Chou, Li Wei
AU - Binder-Macleod, Stuart A.
N1 - Funding Information:
Funding source: NIH Grant Nos. HD36797 and HD38582. The authors thank Dr. R. Perumal and Mr. R. Maladen for their helpful comments on an early draft of this manuscript and for the development of the software and hardware for data-acquisition.
PY - 2008/8
Y1 - 2008/8
N2 - During functional electrical stimulation (FES), both the frequency and intensity can be increased to increase muscle force output and counteract the effects of muscle fatigue. Most current FES systems, however, deliver a constant frequency and only vary the stimulation intensity to control muscle force. This study compared muscle performance and fatigue produced during repetitive electrical stimulation using three different strategies: (1) constant pulse-duration and stepwise increases in frequency (frequency-modulation); (2) constant frequency and stepwise increases in pulse-duration (pulse-duration-modulation); and (3) constant frequency and pulse-duration (no-modulation). Surface electrical stimulation was delivered to the quadriceps femoris muscles of 12 healthy individuals and isometric forces were recorded. Muscle performance was assessed by measuring the percent changes in the peak forces and force-time integrals between the first and the last fatiguing trains. Muscle fatigue was assessed by measuring percent declines in peak force between the 60 Hz pre- and post-fatigue testing trains. The results showed that frequency-modulation showed better performance for both peak forces and force-time integrals in response to the fatiguing trains than pulse-duration-modulation, while producing similar levels of muscle fatigue. Although frequency-modulation is not commonly used during FES, clinicians should consider this strategy to improve muscle performance.
AB - During functional electrical stimulation (FES), both the frequency and intensity can be increased to increase muscle force output and counteract the effects of muscle fatigue. Most current FES systems, however, deliver a constant frequency and only vary the stimulation intensity to control muscle force. This study compared muscle performance and fatigue produced during repetitive electrical stimulation using three different strategies: (1) constant pulse-duration and stepwise increases in frequency (frequency-modulation); (2) constant frequency and stepwise increases in pulse-duration (pulse-duration-modulation); and (3) constant frequency and pulse-duration (no-modulation). Surface electrical stimulation was delivered to the quadriceps femoris muscles of 12 healthy individuals and isometric forces were recorded. Muscle performance was assessed by measuring the percent changes in the peak forces and force-time integrals between the first and the last fatiguing trains. Muscle fatigue was assessed by measuring percent declines in peak force between the 60 Hz pre- and post-fatigue testing trains. The results showed that frequency-modulation showed better performance for both peak forces and force-time integrals in response to the fatiguing trains than pulse-duration-modulation, while producing similar levels of muscle fatigue. Although frequency-modulation is not commonly used during FES, clinicians should consider this strategy to improve muscle performance.
KW - Functional electrical stimulation (FES)
KW - Low-frequency fatigue
KW - Muscle performance
KW - Pulse-duration
UR - http://www.scopus.com/inward/record.url?scp=45849105970&partnerID=8YFLogxK
U2 - 10.1016/j.jelekin.2007.01.001
DO - 10.1016/j.jelekin.2007.01.001
M3 - Article
C2 - 17317219
AN - SCOPUS:45849105970
SN - 1050-6411
VL - 18
SP - 662
EP - 671
JO - Journal of Electromyography and Kinesiology
JF - Journal of Electromyography and Kinesiology
IS - 4
ER -