2011 Volume 25 Issue 1 Pages 53-65
The purpose of this study was to examine the load characteristics during different knee angled leg press exercises at bilateral and unilateral conditions. The subjects were fourteen male jumpers in athletics, aged 22yrs. They performed isometric leg press exercise, knee angled 90° and 120° in bilateral and unilateral conditions. Analyzed outputs were the maximum peak forces and the explosive strengths. The sum of the outputs in unilateral conditions (UL) was compared with the output at bilateral condition (BL) at each of knee angles. Due to the comparison of the muscular activities, the selected six athletes of EMG activities were measured during the tests.
① With regard to the maximum forces, UL were greater than BL and the maximum forces at 120° knee angle were larger than these at 90° knee angle. BL/UL ratios of the peak force at 90° and 120° knee angles were 91％ and 92％ respectively (N.S.).
② UL of the explosive strength at 120° knee angle was greater than the same strength of BL and UL at 90° of the knee angle significantly.
③ As for the EMG activities, the major muscular activities had changed from knee extensor muscles to hip extensor muscles with increase in the knee angles from 90° to 120°. The muscular activities of unilateral conditions were tending to be larger than bilateral condition at each knee angles.
