Kinematical Analysis of Underwater Walking and Running

The purpose of this study was to determine kinematical characteristics of underwater locomotion and to compare them with those of land locomotion. Six male subjects performed walking and running on both conventional and underwater treadmills. Both treadmill speeds increased incrementally starting from 0.56 m s 1 to 3.33 m s 1, the maximum speed of the underwater treadmill. The motion analysis showed that underwater locomotion is characterized by the following points: (a) A transition from walking (1.11 m s 1) to running occurs at a lower speed in water; (b) stride frequency is significantly lower in water; (c) in order to reduce the hydrodynamic resistance of water, a greater knee joint flexion is used to reduce the trajectory area enclosed by the legs as the treadmill speed is increased; and (d) many kinematical differences were observed above a walking speed of 1.11 m s 1, also above this speed oxygen uptake was significantly higher in water. In water, the strategy of locomotion is quite different from that on land.