THE RELATIONSHIP BETWEEN MUSCLE THICKNESS IN THE LOWER LIMBS AND COMPETITION PERFORMANCE IN WEIGHTLIFTERS AND SPRINTERS / 体力科学

This study aimed to investigate the differences in the development of muscle thickness (MT) in the lower limbs with specific sports-event training. Furthermore, the relationship between MT of the lower limbs for weightlifters and sprinters and their competition performances (total weight lifted and 100m sprint times) was examined. Subjects were 64 males divided into 3 groups: weightlifters (n=20), sprinters (n=20), and untrained subjects as controls (n=24). The MT{relative to (body weight)^1/3}of knee extensors (KE), knee flexors (KF), plantar flexors (PF) and dorsi flexors (DF) was measured at 21 sites (proximal, middle and distal) along the length of the upper and lower leg by B-mode ultrasound. The MT of KE for weightlifters was significantly greater than that for sprinters and controls, while the MT of KF and PF for sprinters was significantly greater than that for weightlifters and controls. The MT of rectus femoris (RF), vastus intermedius (VI), vastus lateralis (VL) and vastus medialis (VM) for weightlifters was significantly greater than that for sprinters and controls, while the MT of RF and VM for sprinters was greater than that of controls. On the other hand, the MT of KE for weightlifters and sprinters (especially VM) correlated significantly with competition performances. These results indicated that squatting affected the MT of KE except for RF while sprinting affected the MT of KF and PF. It was also concluded that the MT of KE for weightlifters and sprinters (particularly VM) was related to their competition performances.

RESPONSE OF OXYGEN UPTAKE, HEART RATE, AND VENTILATION TO SUBMAXIMAL ARM, LEG, AND “ARM+LEG” EXERCISE / 体力科学

The effect of submaximal arm, leg, and“arm+leg”exercise on oxygen uptake (VO<SUB>2</SUB>), heart rate (HR), and pulmonary ventilation (V<SUB>E</SUB>) was studied in three male subjects. The“arm+leg”exercise was performed in ten different ways with different arm load ranging from 14 to 60% of the total work load. VO<SUB>2</SUB> and V<SUB>E</SUB> were found higher in the arm exercise than in the other types of exercise at submaximal work. At a given work load, the lowest HR was observed in the“arm+leg”exrcise when the arm was loaded with 14 to 33% of the total work load. And the highest HR was obtained in the arm exercise. The higher HR during the arm exercise as compared to the legor“arm + leg”exercise may be accounted for by the fact that an exercise with small muscle group appears to elicit lower stroke volume and more pronounced rise in sympathetic tone. In the“arm + leg”exercise, HR at a given work load or VO<SUB>2</SUB> varied with the proportion of arm load. However V<SUB>E</SUB>, whcih might be affected by stroke volume, was unaffected by the rate of arm to the total work load at a given work load or VO<SUB>2</SUB>. This indicates that the sympathetic tone may be affected by the proportion of work load distribution on the active msucle groups in the“arm + leg”exercise.