Effects of stride frequency and/or stride length on efficiency in distance running

The purpose of this study was to investigate the effects of change in stride frequency and/or stride length on oxygen uptake during distanc6 running, and to compare female runners with male runners in this point. Ten runners, nine table tennis players and eight swimmers underwent treadmill running at three different speeds. Running speed was constant and stride frequency was systematically changed over a range of ±20 strides/min of the free stride frequency (Experiment 1). Five male runners and four female runners ran on a treadmill at stride lengths between 60 cm and 130 cm with a given stride. frequency (160, 180 or 200 strides/min) and at stride frequencies between 150 and 200 strides/min with a given stride length (80 or 100cm) (Experiment 2). The measurements of oxygen uptake and HR were made during steady state in each running. 1) The most economical stride frequency (optimal stride frequency) in males always coincided with the free stride frequency. Both increase and decrease in stride frequency from the free stride frequency caused increase in oxygen uptake in male runners. Regarding female runners, oxygen uptake during distance running was a1most constant over a wide range of stride frequency (170-220). Specific optimal stride frequency was not observed in female runners. 2) Running with a given stride frequency caused a rectilinear relationship between oxygen uptake and stride length in male and female runners. It was suggested that change in stride length scarcely affected running efficiency during distance running. 3) There was an obvious difference between male and female runners in the effect of change in stride frequency on oxygen uptake during distance running with a given stride length. Decrease in stride frequency below 170 strides/min lowered the running efficiency in runners of both sexes. Above 180 strides/min, there was an exponential relationship between oxygen uptake and stride frequency in male runners, and a rectilinear relationship in female runners. Stride frequency higher than 180/min lowered running efficiency in male, but not in female runners. 4) Optimal stride frequency was observed in male runners, table tennis players and swimmers. Optimal stride frequency always coincided with free stride frequency in male subjects, and it was suggested that men without special training can run with the most economical stride frequency. 5) Stride length and stride frequency increased linearly as the running speed increased. Increase in running speed was dependent much more on increase in stride length than that of stride frequency. Contribution of stride frequency to an increase in running speed was more significant in female than male.