Abstract
The aim of the present study was to examine how the recovery of physiological functioning of the leg muscles after highintensity
eccentric exercise such as downhill running could be promoted by aqua exercise for a period until the damaged
muscle had recovered almost completely. Ten male long-distance runners were divided equally into an aqua exercise group
and a control group. From the first day (Day 0) to the fourth day (Day 3), the participants completed a questionnaire on
muscle soreness, and serum creatine kinase activity, muscle power, flexibility, whole-body reaction time and muscle stiffness
were measured. After measurements on Day 0, the participants performed downhill running (three 5min runs with a 5 min
rest interval at 710%, 335.7+6.1m min71). The aqua exercise group performed walking, jogging and jumping in water
on three successive days following the downhill running on Day 0 for 30 min each day. Muscle power was reduced on Day 1
in the control group (P50.05). Muscle soreness in the calf on Day 3 was greater in the control group than that in the aqua
exercise group (P50.05). In the aqua exercise group, muscle stiffness in the calf was less than that in the control group over
4 days (time main effect: P50.05; group6time interaction: P50.05). We conclude that aqua exercise promoted
physiological functioning of the muscles in the legs after high-intensity downhill running for a period until the damaged
muscles had recovered almost completely.