MMG-EMG cross spectrum and muscle fiber type.
The purpose of this study was to investigate fiber type-related differences in the patterns of responses for mechanomyographic-electromyographic (MMG-EMG) cross spectrum mean power frequency (MPF) in resistance-trained and aerobically-trained subjects during a fatiguing muscle action. Five resistance-trained and five aerobically-trained men performed a 45-s isometric muscle action of the dominant leg extensors at 50% MVC while MMG and EMG signals were recorded simultaneously from the vastus lateralis muscle. In addition, a biopsy was taken to determine the myosin heavy chain (MHC) isoform content of the vastus lateralis. The resistance-trained and aerobically-trained subjects demonstrated similar patterns of responses for MMG-EMG cross spectrum MPF during the sustained muscle action. The vastus lateralis of the resistance-trained subjects demonstrated primarily Type II MHC isoform expression, indicative of fast-twitch muscle fibers, while that of the aerobically-trained subjects was composed mostly of Type I MHC isoform expression, indicative of slow-twitch fibers. Thus, the differences in fiber type characteristics were not manifested in the patterns of responses for MMG-EMG cross spectrum MPF.
Beck
T W
TW
Department of Health and Exercise Science, University of Oklahoma, Huston Huffman Center, Norman, OK 73019-6081, United States. tbeck@ou.edu
Housh
T
T
Fry
A C
AC
Cramer
J T
JT
Weir
J
J
Schilling
B
B
Falvo
M
M
Moore
C
C
D000328:Adult; D004576:Electromyography / Q000379:methods*; D015444:Exercise / Q000502:physiology; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology; D018656:Muscle Fibers, Fast-Twitch / Q000502:physiology; D018657:Muscle Fibers, Slow-Twitch / Q000502:physiology; D009213:Myography / Q000379:methods*; D018995:Myosin Heavy Chains / Q000502:physiology; D052097:Quadriceps Muscle / Q000502:physiology; D055815:Young Adult
D018995:Myosin Heavy Chains