Six young males walked in a swimming pool, swimming flume and land treadmill at 0.4, 0.6 and 0.8 m·⋅^-1. At 0.6 and 0.8 m⋅s^-1, VO₂and HR values were significantly lower for the swimming flume walking than for the swimming pool waking. At rest and 0.4 m⋅s^-1, there were no significant VO₂differences between swimming flume walking and land treadmill walking ; while significantly lower HR values were found for swimming flume walking. There was no significant difference in the VO₂-HR relationship between land treadmill waking and swimming pool waking. On the other hand, a significant downward sift in the regression line was observed in swimming flume waking compared to land treadmill walking. The differences between the two types of underwater walking exercise may produce a different effect concerning the muscle pump on leg muscles. Soleus, and especially lateral gastrocnemius muscles, showed lower electromyogram activity at push-off phase during swimming flume walking compard with swimming pool walking. This activity may contribute to the lower VO₂and HR values during swimming flume walking. It is apparent that the swimming flume walking has different physiological and kinematic characteristics such leg muscles EMG activity walking or swimming pool walking.