2012 Volume 9 Pages 9-17
Lifecorder EX (LC) is a useful accelerometer to assess physical activity, but its accuracy has not been assessed sufficiently: the effect of gender on LC accuracy remains unclear. This study was undertaken to examine gender effects on the LC accuracy to estimate the metabolic equivalent (MET) and LC accuracy during walking and running. The 45 healthy Japanese participants (23 male, 22 female) examined in this study were divided into two groups: a calibration group (16 male, 14 female) and a cross-validity group (7 male, 8 female). The participants performed 5 min of treadmill walking at 3.6, 4.8, and 6.0 km•h-1, and treadmill running at 7.2 and 9.6 km•h-1. The LC was placed on the waist. Simultaneous measurements obtained using the LC and an indirect calorimeter (IC) were recorded continuously during exercises. The gender effect was analyzed from data of the calibration group using mixed models. The LC accuracy was assessed with the cross-validation group using three-way repeated ANOVA models and root mean squared error (RMSE). In the calibration group, the results of mixed models revealed that the gender had no influence on the relationship between the IC measurements and the LC estimates (p > 0.577). In the cross-validation group, although no significant difference was found between the IC measurements and the LC estimates at any treadmill speed (p > 0.061), RMSE at running speeds (7.2 and 9.6 km•h-1) rapidly increased more than those during walking. The results suggest that the LC can assess MET of men and women accurately, but the LC was unable to estimate MET during running.