MMG and EMG responses during 25 maximal, eccentric, isokinetic muscle actions.
OBJECTIVE
The purpose of this study was to examine the patterns of the mechanomyographic (MMG) and electromyographic (EMG) amplitude responses of the vastus lateralis (VL), rectus femoris (RF), and vastus medialis (VM) during 25 maximal, eccentric, isokinetic muscle actions.


METHODS
Seven healthy adult females (22.1 +/- 2.4 yr) completed 25 maximal, eccentric muscle actions on a calibrated Cybex 6000 isokinetic dynamometer. EMG and MMG signals were obtained from the VL, RF, and VM during this test, and polynomial regression models were used to examine the relationships for normalized torque, EMG amplitude, and MMG amplitude versus repetition number.


RESULTS
There was a cubic relationship (P < 0.05) between torque and repetition number. EMG amplitude demonstrated a positive linear relationship (P < 0.05) for the VL, a quadratic relationship (P < 0.05) for the RF, and no relationship (P > 0.05) for the VM over the 25 repetitions. MMG amplitude demonstrated a negative linear relationship (P < 0.05) for both the VL and VM, and a cubic relationship (P < 0.05) for the RF over the 25 repetitions.


CONCLUSIONS
The results of the present study demonstrated differences between the VL, RF, and VM muscles for the patterns of EMG and MMG responses across the 25 maximal, eccentric muscle actions. These findings suggested that there are muscle-specific motor control strategies during repeated eccentric, isokinetic muscle actions.
Perry-Rana
Sharon R
SR
Ohio University, College of Health and Human Services, School of Recreation and Sport Sciences, Athens 45701, USA. rana@ohio.edu
Housh
Terry J
TJ
Johnson
Glen O
GO
Bull
Anthony J
AJ
Cramer
Joel T
JT
D000328:Adult; D001696:Biomechanical Phenomena; D004576:Electromyography; D005260:Female; D006801:Humans; D007700:Kinetics; D007866:Leg / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D010507:Periodicity; D019415:Torque