Activity Monitors, often referred to as accelerometers, assess the acceleration of the body in a specific dimension (uniaxial) or multiple dimensions (triaxial). The monitors provide information on the intensity of acceleration at specified intervals. Following data collection, this information is downloaded to a computer for data processing. PROS. Objective measure of body movement that has been found to be valid in both laboratory and free-living settings. Activity monitors have the ability to provide information relating to intensity, frequency, and duration of physical activity. They are also non-invasive and have the ability to record over extended periods of time. CONS. They are costly and do not provide information concerning activity type. Also, the uniaxial monitors may be inaccurate during upper-body movements and during bicycling. Most activity monitors are not waterproof; therefore, water-based activities cannot be assessed. Also, improper monitor placement may lead to inaccurate results.