Method of calculating mechanical power in swimming the breast stroke.

Abstract The work output in swimming the breast stroke was estimated by means of specially derived formulas in addition to photography. Four different subjects swam 25 m with their best efforts. The movements were filmed by 16 mm high speed camera and progressive speed was analyzed. The trained swimmers were fairly superior in speed to the untrained. The periods of the stroke cycle for the trained were much shorter than those for the untrained. The mechanical work output was estimated from the data for speed variations and water resistance. The high power (0.12–0.47 hp.) is produced during the kicking phase. After kicking is completed, no work is done for a short period (0.13–0.23 sec.) by the trained and for a long period (0.38–0.47 sec.) by the untrained. Again, the high power (0.38–0.47 hp.) is produced by the trained and the low power (0.11–0.14 hp.) by the untrained during the pulling phase. Then minus power is produced during the recovery phase by all subjects.