Heart Rate Monitoring has been used in both clinical and research settings to estimate activity-related energy expenditure based upon the assumption of a linear relationship between heart rate and oxygen consumption (VO2). (Wilmore, 1971)1 Because the HR-VO2 relationship is somewhat attenuated during low and very high intensity activities (Acheson, 1980)2, and because of considerable between person and day–to–day HR–VO2 variability (Li, 1993;3 McCrory, 19974), individual HR–VO2 calibration technique is rather cumbersome.
Several studies (Welk 20025, Crouter 20046, Kurpad 20067) have found that calibration is required to create a curve between the subject's heart–rate and estimated energy expenditure, involving a sub–maximal stress test at moderate activity levels (Freedson and Miller 20008, Crouter 2004, Kurpad 2006).
The actual heart rate monitoring itself is easy and quick to administer and can be utilized in either a laboratory or free–living setting. It is modestly in the assessment of physical activity intensity and has been utilized in both children (Beghin, 2002)9 and adults (Strath, 2002;10 Kashiwazaki, 198611). Unfortunately, there is the potential for heart rate monitoring to cause an alteration in activity behavior. Heart rate monitoring is usually limited to a short time frame. Lastly, body temperature, size of the active muscle mass (e.g. upper vs. lower body), type of exercise (static vs. dynamic), stress, and medication influence HR, which may result in an estimation of activity–related energy expenditure (Acheson, 1980; Montoye, 199612).