Prediction of energy expenditure from pedometer output across different activities in young healthy adults

Abstract

Purpose. The New Lifestyles NL-1000 pedometer is a suitable device for cost-efficient assessment and promotion of physical activity owing to low cost and accuracy. This study examined if step rate as determined by the NL-1000 pedometer predicted the rate of oxygen uptake (VO2) across different activity types in young healthy adults and evaluated the accuracy of such prediction. It was also investigated if height, body mass index (bMI), and sex contributed to the prediction. Methods. The study involved 36 healthy young adults (21 ± 4 years; 16 women). The participants completed 8 activities, each lasting 6 minutes: (a) sitting; (b) slow walking; (c) fast walking; (d) jogging; (e) moving a box; (f) washing dishes; (g) ascending-descending stairs; and (h) vacuuming. We measured VO2 with a portable open-circuit spirometer and step rate with the NL-1000 pedometer worn on the non-dominant hip. We used multi-level regression to predict VO2 and determined the absolute percent error of the VO2 prediction model with the leave-one-participant-out cross-validation procedure. Results. Significant predictors of VO2 were step rate and its square (p< 0.001; R2 = 0.72), but not height, bMI, or sex. Absolute error across all activities combined was 29.7 ± 27.6%. Absolute error differed between activities (p < 0.001). Conclusions. Pedometer-determined step rate and its square were significant predictors of VO2 across different activities in healthy young adults. Height, bMI, or sex did not contribute to VO2 prediction. Accuracy of prediction across activities was low to moderate.