Reliability of physical activity and heart rate measures in children during steady rate and intermittent treadmill exercise: The A-CLASS project

To help clarify the dose-response relationship between physical activity (PA) and health outcomes, a PA measurement tool must be valid and demonstrate adequate reliability (Wareham and Rennie, 1998). To date only one reported study has assessed the test-retest reliability of field-based PA monitors with participants (Rowlands et al., 2007). In trained runners undergoing identical treadmill trials, ActiGraph accelerometer (GT1M, Fort Walton Beach, FL) reliability was high between 4-20 kph but RT3 triaxial accelerometer (Stayhealthy, Inc., Monrovia, CA) reliability was poor at midrange and high speeds (Rowlands et al., 2007).