Physical activity level (PAL)
PAL was objectively quantified using a movement sensor (ActiGraph GT3X;
ActiGraph, Pensacola, FL, USA). All units were initialized via a
computer interface, and data were collected in 15-sec epochs in all
three dimensions using specific software (ActiLife 6.9.5 Firmware
version). Each adolescent was instructed to wear the movement sensor on
the hip (non-dominant side) using an elastic belt for seven consecutive
days. The data are presented as the average number of steps per day and
the time spent performing moderate-to-vigorous physical activity (MVPA,
min*d-1), performing light-intensity physical
activity, and sitting (18). Adolescents were considered successfully
monitored when they used the accelerometer for at least four days for
more than 10 hours per day.