Abstract
This study was designed to compare post-exercise hyperemia between ramp and ballistic contractions in human triceps surae. Subject was asked to extend ankle joint in range of 20 degrees for 1 sec and with maximum effort against loads of 10, 20, 30 or 40% of maximum voluntary contraction (MVC) in ankle extensors. Amount of post-exercise hyperemia was calculated from changes in calf girth recorded by using two strands mercury-in-rubber gauge.
1) Calf girth after contractions transiently decreased below precontraction level and increased gradually until its peak value, over precontraction level, in about 8 sec. Calf girth recovered to resting level for about 30 sec.
2) After ramp contractions, amount of decrease of calf volume increased in order to loads of 10, 20, 30 and 40% MVC, but was not so after ballistic contractions. Amount of its increase, excess precontraction level, depended on loads in both conditions. These values were below 1.0ml/100 ml tissue.
3) Amount of decrease of calf volume after ramp contraction was larger than that of ballistic contraction, but amount of its increase was inverse.
4) There was significant coefficient between calf volume increase after contraction and maximum inflow rate (ml/min/100 ml tissue) calculated from the maximum gradient in rising phase of calf girth (r=0.5508, p<0.001) .
From these results, it is suggested that“milking action”in muscle generate with ramp contraction, and that disturbance of pulsatile inflow to muscle and chemical and neuronal regulations to generate post-exercise hyperemia pronouncely act by ballistic contraction.
