1999 Volume 3 Issue 1 Pages 12-19
To achieve excellent performance in distance running, as well as maintaining greater physiological energy level, distance runners have to learn running technique to effectively convert the physiological energy to running velocity in race. The purpose of this study was to investigate factors affecting the effectiveness of mechanical energy utilization in 5000-m race and the relationships to running technique. Runners who participated in official 5000-m races were videotaped at 60 fields/s with a VTR camera for two-dimensional analysis. Coordinates of the segment end points for thirty-two male runners were obtained by digitizing VTR images at 2000-m and 4000-m marks. Kinematic and kinetic variables were calculated and effectiveness index of mechanical energy utilization in running (EI) was computed by equation (1).
EI =
Effective Energy / Mechanical Work = (1/2 MV2X) / Wwb (1)
Faster runners showed higher EI than slower runners. EI was positively related to mechanical energy transfers between segments (r=0.582, p<0.001) and negatively to mechanical energy changes in the torso (r=-0.740, p<0.001) during a running cycle. EI was affected by mechanical energy transfer between both legs. There were positive correlations between EI and positive mechanical work at the right hip joint in both early and late recovery phases (respectively, r=0.508, p<0.001; r=0.564, p<0.001). EI was significantly related to the vertical displacement and the deceleration in the velocity of the center of gravity (C.G.) in the first half of support phase and the knee angle at mid-support (respectively, r=-0.344, p<0.01; r=-0.381, p<0.01; r=0.362, p<0.01). These results suggest that to increase EI runners should decrease the displacement of the C.G. and the flexion of the support leg in the first half of the support phase, recover the thigh quickly with the emphasis of a scissors-like motion of the thighs, i.e. one thigh swinging forward and the another swinging reverse, so as to enhance transferring of mechanical energy between both legs.
