The Effect of Small Increases in Stride Frequency on Oxygen Consumption During Walking

Abstract

PURPOSE: Humans tend to self-optimize during walking choosing the stride frequency (SF) associated with the lowest oxygen consumption. Research has shown that a 15% increase in SF above preferred stride frequency (PSF) increases oxygen consumption but no research has examined the effect of smaller increases in stride frequency. Oxygen consumption is directly related to caloric expenditure (4.825 kcal/L O2) so an increased SF would elicit an increase in calories burned. Therefore the purpose of this study was to determine the stride frequency at which oxygen consumption was raised significantly above that at the PSF. METHODS: Fourteen subjects (22.6±2.5 years, 1.7±0.1 m, 68.9±12.8 kg) participated in this study. Each subject walked on a treadmill to determine his or her preferred walking speed and PSF. The subjects then completed four walking trials while paced at four different stride frequencies: PSF, PSF+3%, PSF+6% and PSF+9%. Oxygen consumption data was obtained via indirect calorimetry. A repeated measures ANOVA tested for differences among stride frequency conditions (p<.05). RESULTS: The mean oxygen consumption values for these frequencies were 0.914± 0.175, 0.919 ± 0.19, 0.950 ± 0.214 and 0.977 ± 0.215 L/min, respectively. Posthoc comparisons revealed that oxygen consumption at the PSF+9% condition was significantly greater than the PSF and PSF+3% conditions. CONCLUSIONS: Since the PSF and PSF+3% values were not significantly different, but both were significantly less than PSF+9%, these data suggest that stride frequency must be increased at least 9% to elicit a significant increase in oxygen consumption. This 9% increase was associated with a 0.063 L/min increase in oxygen consumption and a related increase in caloric expenditure of 0.31 kcal/min. In one hour of fitness walking, a 9% increase in SF would result in 19 more kcals burned. If a person follows this strategy for 4 hours/ week over the course of one year, this would translate into 4,000 additional calories burned, or over one pound of body weight lost.