ABSTRACT
The purpose of this study was to investigate the landing impacts of falls from short heights with body weight increment. Eight male college students participated as subjects. The body weight increments were gradually increased by 2, 4, 6, 8 and 10 kg by attaching 500 gram iron bars in the pocket of vests that students wore. The subjects performed the landing by falling from a height of 2.7 m above and they landed on the surface of a force plate as softly as possible. The landing impacts, muscular activities, and joint movements of lower limbs during landing were analyzed by a force plate using EMG and VTR programs.The results indicated that there were no significant increments found in maximal landing impact even though the body weight was increased from 2 to 10 kg. The flexion of ankle, knee and hip joints started immediately before landing and increased after landing with the body weight increments. The activity of plantar and dorsi flexor muscles after landing were increased intensively with the body weight increments. Although the body weight increased from 2 to 10 kg gradually, landing impact at fall did not increase. It may be controlled by fast and deep flexing movements of lower limb joints during landing.
ABSTRACT
A study was conducted to investigate the influence of motor learning on functional specialization of the upper and lower limbs by comparing automatized levels in upper and lower limb movements between 17 soccer (S group) and 14 basketball (B group) players at a university. They carried out transitory palmar flexion of both hands while stepping and performing alternate flexion-extension movements of both ankle joints, and transitory plantar flexion of both feet while performing alternate flexion-extension movement of both shoulder joints and both wrist joints. The automatized levels of the upper and lower limb movements were evaluated by the degree of interference between the upper and lower limb movements.<BR>It was shown that automatization of lower limb movements was more advanced than that of upper limb movements in both groups. The automatized levels of stepping in the S and B groups showed no significant difference, and were similar to those of university students in general obtained in our previous study. However, the automatized levels of ankle joint movements in both groups were higher than those for university students in general.<BR>In both groups, the insertion of transitory palmar flexion was restricted to within the phase where the degree of interference was small during the stepping and ankle joint movement. However, this tendency was not clear in the trial where transitory plantar flexion was superimposed on shoulder joint and wrist joint movements.<BR>As for the difference between the groups, the S group showed a higher automatized level of ankle joint movement than the B group. On the other hand, the B group showed higher automatized levels of both upper limb movements than the S group, and this tendency was especially evident for shoulder joint movement.<BR>These results suggest that the change in the automatized level of upper and lower limb movements by specific motor learning is added to the functional specialization of the upper and lower limbs acquired by daily basic motor learning in an upright position.