What is the minimum step rate required to achieve moderate-intensity walking overground in adolescent girls?

Abstract

Background: In order to promote walking, researchers have sought to identify the required step rate to maintain a healthenhancing walking intensity However, there is limited evidence regarding the stepping rate required to promote moderateintensity walking in adolescent girls. Purpose: To identify the step rate equivalent to moderate-intensity physical activity (MPA) in adolescent girls and to explore the influence that different anthropometric measures may have on the step rate equating to MPA in this population. Methods: A total of 56 adolescent girls (mean age = 13.8[0.7] y) were recruited to the study. Anthropometric variables and resting metabolic rate were assessed, followed by 3 overground walking trials on a flat surface at approximately 2, 3, and 4 mph, each lasting a minimum of 4 minutes. Oxygen uptake was assessed using a portable gas analyzer and subsequently converted into metabolic equivalents (METs). Step count was assessed by real-time direct observation hand tally. Results: Employing the linear regression between step rate and METs (r2 = .20, standard error of estimates = 0.003) suggests that 120 steps per minute was representative of an MPA (3 METs) equating to 7200 steps in 60 minutes. Multiple regression and mixedmodel regression confirmed weight-related variables and maturity were significant predictors of METs (P < .01). Conclusion: The results suggest that, at population level, a step rate of 120 steps per minute may be advocated to achieve MPA in adolescent girls; although, due to the small sample size used, caution should be applied. At an individual level, other factors, such as age and weight, should be considered.