Kagemoto Yuasa

Effect of running velocity on external mechanical power output

The mechanical power output and work done in running were measured for eight athletic runners by means of a strain gauge platform and 16mm cine camera. The angle between the line connecting the centre of gravity of the body with the foot on the ground and the horizontal line was about 110 degrees at the moment of foot contact with the ground, independent of running velocity. The external work by velocity change (Wf) increased curvilinearly with the running velocity up to about 630 Joule kg-1 at maximum velocity. The mechanical power output per body weight in forward direction (Pf) increased as the 2nd power of the running velocity and the following equation was obtained Pf=0·436V2·01 f where Pf was expressed in Wkg-1 and Vf in ms-1. At the velocity higher than 6ms-1, the mechanical power by forward velocity changes (Pf) increased gradually greater than that against gravity (Pv) but at the lower velocity than 5ms-1 Pf was always less than Pv.

The Relationship between Integrated EMG and Oxygen Uptake during Treadmill and Bicycle Exercise

The aim of this study is to measure the integrated EMG in relation to the oxygen uptake during submaximal treadmill and bicycle exercises. Seven healthy adult subjects performed five minute exercise at three different submaximal work intensities on the same day. The EMG activity in right thigh and leg muscles was measured from m. rectus femoris, m. biceps femoris, m. tibialis anterior and m. gastrocnemius by means of four pairs of surface electrodes sealed with collodion to the skin at a distance of 3 cm apart over the belly of muscles. The EMG activity was not likely modified by the possible fatigue during 5 minutes submaximal exercise in this experiment. In the treadmill walking, there was a rectilinear relationship between integrated EMG activity from four muscle groups and percent of VO2max. On the bicycle exercise the correlation coefficient between them was generally lower than that on the treadmill walking. The product of integrated EMG and volume of the same muscle groups was considerably linearly related to oxygen uptake during treadmill and bicycle exercise (the correlation coefficient was 0.945, p < 0.001 in treadmill and 0.710, p < 0.001 in bicycle).