MARTIN, THOMAS P. and JOHN S. BERNFIELD. Effect of stroke rate on velocity of a rowing shell.Med. Scl. Sports Exercise, Vol. 12, No. 4, pp. 250–256, 1980. In order to examine the effect of stroke rate changes on the velocity-time curve of a rowing shell, the 1976 U.S. Olympic eight-oared crew was filmed rowing six trials each at stroke rates of 37, 39, and 41 strokes per min. Shell instantaneous velocity was calculated and plotted for positions throughout the stroke cycle and a cubic spline curve was fitted to these data points. Actual stroke rate, boat average velocity, and selected parameters of the velocity-time curves were calculated to examine the relationships between variables. In addition, times for phases of the stroke cycle were determined in order to analyze crew technique. Minimum shell velocity occurred approximately 27% into the leg drive phase and maximum velocity occurred during the middle of the seat movement phase. Average minimum shell velocity for all trials deviated −24.4% from the mean velocity while the average maximum velocity deviated + 18.6%. A significant positive relationship (r= .66) was found between stroke rate and average velocity. In analyzing the phases of the stroke cycle, it was determined that increased boat velocity was accomplished by a greater application of force during the drive phase and, more importantly, the exertion of force over a greater percentage of the time for the stroke cycle.