To estimate the effect of aqua walking for exercise prescription, oxygen uptake (Vo₂), heart rate (HR) and electromyographic data (EMG) of working muscles were measured in seven healthy female college students. Three bouts of actual walking in water (27.0 ± 0.5 ℃) with the depth of 0.9 and 1.3 m were conducted. From the results of Vo₂ (72.9 ± 7.9% Vo₂max) and HR (151.4 ± 12.1 bpm) which were obtained from the fast walking bout (46.0 ± 2.1 m/min) performed in shallow water, it is concluded that aqua walking has a sufficient intensity for exercise prescription. The estimated Vol was determined by applying the HR data obtained from aqua walking to the relationship between Vo₂ and HR obtained from the incremental walking test on a treadmill (0.4～2.4 m/sec). The estimated Vo₂ was significantly (P< 0.01) smaller than the actual Vo₂ obtained during aqua walking. This result suggests that to apply the relationship between Vo₂ and HR during walking on land to estimating exercise intensity during walking performed in water should be avoided.
　In addition, the increased electric activity of m. gastrocnemius, m. tibialis anterior and m. rectus femoris estimated from surface EMG showed that aqua walking has an effect for avoiding the decrease of performance of leg muscles.

DESCENTE SPORTS SCIENCE Vol.15/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE