Gender comparisons of the mechanomyographic responses to maximal concentric and eccentric isokinetic muscle actions

Purpose: The purpose of this study was to determine whether there is a gend er difference in the velocity-related patterns of mechanomyographic (MMG) r esponses to maximal isokinetic concentric (CON) and eccentric (ECC) muscle actions. Methods: Adult males (N = 15) and females (N = 16) performed maxim al CON and ECC muscle actions of the leg extensors on a calibrated Cybex 60 00 dynamometer at velocities of 30, 90, and 150 degrees.s(-1). MMG was dete cted by a piezoelectric crystal contact sensor placed over the vastus later alis muscle. Results: The results indicated that there were decreases in CO N peak torque (PT) across velocities, while ECC PT remained constant with i ncreasing velocity for both genders. MMG amplitude increased significantly (P < 0.05) with velocity in both the males and females for CON and ECC musc le actions. There was a gender difference in the velocity-related patterns of MMG responses to maximal isokinetic CON muscle actions; however, there w as no gender difference in the pattern of ECC MMG responses. Conclusions: T he gender difference in CON MMG responses may be attributed to the greater percent decline in CON PT across velocity for the females than the males. I n addition, the males displayed greater CON and ECC MMG amplitudes at all m uscle action velocities than the females, possibly because of gender differ ences in muscle mass and/or thickness of the adipose tissue layer.