Translating The Moderate-to-vigorous Physical Activity Recommendation To Steps Per Day: Influence Of The Cut-point Method

Abstract

The Organization recommends adolescents to engage in at least 60 minutes/day in moderate to vigorous physical activity (MVPA). However, this recommendation is not easily understood by both adolescents and their parents. Although a more practical steps/day recommendation is available, empirical studies examining total daily steps translation of the MVPA recommendation in adolescents are scarce and inconsistent, offering a wide range from 7,500 to 14,000 steps/day. Variation between instruments, methods, and statistical considerations may also contribute to the variability in daily steps thresholds. To our knowledge there are not previous studies examining the influence of the optical cut-point method to translate MVPA recommendation into steps/day. PURPOSE: To examine the influence of the optical cut-point method on the translation of the 60 minutes of MVPA recommendation to steps/day in adolescents. METHODS: 126 Chilean adolescents (70 males and 56 females) aged 12-15 years old wore ActiGraph GT3X accelerometers for eight consecutive days. Activity counts/min ≥ 2,296 were used to determine MVPA. ROC analyses (daily MVPA as reference standard: < 60 min/day and ≥ 60 min/day; and daily total steps as index test) with the 34 available optical cut-point methods were performed using the web-tool easyROC version 1.3.1. RESULTS: A small percentage (10.3%) of adolescent participants achieved ≥60 min/day of MVPA. ROC analyses showed an excellent accuracy (AUC = 0.95, 0.90-1.00) for translating the MVPA recommendation to steps per day. The daily step-based recommendation greatly varied between the 34 examined optical cut-point methods (mean = 10,318; median = 9,898; minimum = 3,262; maximum = 14,899; P25 = 8,656; P75 = 13,581). CONCLUSION: The optical cut-off methods to determine the optimal steps/day cut-point threshold based on current MVPA recommendation for adolescents may drastically affect the step-based recommendation. Further studies should examine the daily step-based thresholds adopting the best evidence-based decisions regarding the optical cut-point method.