Determination of Step Rate Thresholds Corresponding to Physical Activity Intensity Classifications in Adults

Abstract

Current recommendations call for adults to be physically active at moderate and/or vigorous intensities. Given the popularity of walking and running, the use of step rates may provide a practical and inexpensive means to evaluate ambulatory intensity. Thus, the purpose of this study was to identify step rate thresholds that correspond to various intensity classifications. Oxygen consumption was measured at rest and during 10 minute treadmill walking and running trials at 6 standardized speeds (54, 80, 107, 134, 161, and 188 m·min⁻¹) in 9 men and 10 women (28.8 ± 6.8 yrs). Two observers counted the participants' steps at each treadmill speed. Linear and nonlinear regression analyses were used to develop prediction equations to ascertain step rate thresholds at various intensities. Nonlinear regression analysis of the metabolic cost versus step rates across all treadmill speeds yielded the highest R² values for men (R² = .91) and women (R² = .79). For men, the nonlinear analysis yielded 94 and 125 step·min⁻¹ for moderate and vigorous intensities, respectively. For women, 99 and 135 step·min⁻¹ corresponded with moderate and vigorous intensities, respectively. Promoting a step rate of 100 step·min⁻¹ may serve as a practical public health recommendation to exercise at moderate intensity.