Our findings reveal there is a strong linear relationship between wrist- and hip-worn accelerometer out-put among adolescents in free-living conditions. Adolescent compliance was significantly higher with wrist placement, with participants reporting that it was more comfortable and less embarrassing to wear on the wrist.

These findings suggest the single-item measure can provide a reliable and valid assessment of youth physical activity.

The aim of this study was to investigate adolescents' potential reactivity and tampering while wearing pedometers by comparing different monitoring protocols to accelerometer output. The sample included adolescents (N = 123, age range = 14-15 years) from three secondary schools in New South Wales, Australia. Schools were randomised to one of the three pedometer monitoring protocols: (i) daily sealed (DS) pedometer group, (ii) unsealed (US) pedometer group or (iii) weekly sealed (WS) pedometer group. Participants wore pedometers (Yamax Digi-Walker CW700, Yamax Corporation, Kumamoto City, Japan) and accelerometers (Actigraph GT3X+, Pensacola, USA) simultaneously for seven days. Repeated measures analysis of variance was used to examine potential reactivity. Bivariate correlations between step counts and accelerometer output were calculated to explore potential tampering. The correlation between accelerometer output and pedometer steps/day was strongest among participants in the WS group (r = 0.82, P ≤ 0.001), compared to the US (r = 0.63, P ≤ 0.001) and DS (r = 0.16, P = 0.324) groups. The DS (P ≤ 0.001) and US (P = 0.003), but not the WS (P = 0.891), groups showed evidence of reactivity. The results suggest that reactivity and tampering does occur in adolescents and contrary to existing research, pedometer monitoring protocols may influence participant behaviour.

The science and practice of step counting in children (typically aged 6-11 years) and adolescents (typically aged 12-19 years) has evolved rapidly over a relatively brief period with the commercial availability of research-grade pedometers and accelerometers. Recent reviews have summarized considerations for assessing physical activity using pedometers in young people (both children and adolescents), but 3 areas have received little attention: pedometer monitoring protocols, minimal (as opposed to optimal) step counts necessary for maintaining basal levels of health, and appropriate pedometer-based interventions for young people. Therefore, the objective of this review was to evaluate the current evidence and identify future research directions in these areas. The challenges of objective monitoring of physical activity in children and adolescents reinforce the importance of using protocols that minimize participant burden and the potential for tampering/reactivity. Evidence for a sedentary lifestyle cut point is limited; researchers are therefore encouraged to investigate several cut points (ie, <5000, <6000, <7000 steps/d) in children and adolescents to identify the health consequences of very low levels of ambulatory activity. Personalized messages may be necessary for health behavior change in pedometer-based interventions, but there is a need for more high-quality studies to develop the existing evidence base.