The effect of using paddles on hand propulsive forces and Froude efficiency in arm-stroke-only front-crawl swimming at various velocities.

Through pressure measurement and underwater motion capture analysis, this study aimed to elucidate the effects of hand paddles on hand propulsive forces, mechanical power, and Froude efficiency in arm-stroke-only front-crawl swimming at various velocities. Eight male swimmers swam under two conditions in randomized order, once using only their hands and once aided by hand paddles on both hands. Each participant swam 10 times a distance of 16 m in each condition, for a total of 20 trials. To elucidate the relationship between propulsive forces and swimming velocity, each participant was instructed to swim each of the two sets of 10 trials at an arbitrarily different swimming velocity. During the trials, pressure sensors and underwater motion capture cameras were used together to analyze the pressure forces acting on the hand and hand kinematics, respectively. Six pressure sensors were attached to the right hand, and pressure forces acting on the right hand were estimated by multiplying the areas with the pressure differences between the palm and dorsal side of the hand. Acting directions of pressure forces were analyzed using a normal vector perpendicular to the hand or hand paddle, calculated from coordinates obtained using underwater motion capture analysis. As a result, there were no differences in propulsive forces and mechanical power to overcome water resistance (PD ) with or without hand paddles at the same swimming velocities. However, the use of hand paddles decreased stroke rate and hand velocities, so mechanical power to push the water at the hand (PK ) decreased. Using hand paddles thus increased Froude efficiency (ηF ). These results suggest that training load decreases when swimmers swim at the same velocities while using hand paddles. This insight could prove useful for coaches and swimmers when using hand paddles for training to help ensure that they are used in accordance with their intended training purpose. If swimmers use hand paddles increasing propulsive force or PK , they should swim at a higher swimming velocity with hand paddles than without.