![]() Participants reported to the laboratory having fasted for four hours, having abstained from nicotine, caffeine, or other stimulants for four hours, and having refrained from exercise for 24 hours. Ambulatory activities, home/office activities, and sport activities were examined. Thus, the purpose of this study is to examine whether the left wrist GENEA cut-points developed by Esliger and colleagues are accurate for predicting intensity categories. To date, however, these cut-points have not been cross-validated in a separate study. The authors speculate that the tight clustering of their data within each activity will allow for an increased accuracy of activity classification. ( 9) showed high levels of criterion validity (r=0.85) across a range of activities, including home/office and ambulatory activities, which was approximately equal to that seen with the waist-mounted ActiGraph GT1M and the RT3( 9). The physical activity intensity cutpoints for the GENEA accelerometer developed by Esliger et al. ![]() Furthermore, due to its wristwatch-like characteristics and size, the GENEA will potentially encourage higher rates of wear compliance, when compared to waist-worn accelerometers ( 26). A newly introduced wrist-worn accelerometer-based physical activity monitor, the Gravity Estimator of Normal Everyday Activity (GENEA), has been reported to have high accuracy for classifying physical activity intensity (e.g., sedentary, light, moderate, vigorous) ( 9). Researchers have attempted to place accelerometers on the ankle, upper arm, wrist, or multiple sites of the body ( 4, 29). Therefore, alternative sites for placement that may elicit improved results compared to the waist-worn sensors could enhance future research ( 7). Placed near the center of mass, waist-mounted accelerometers fail to detect arm movements, which leads to significant measurement errors and physical activity intensity misclassification ( 7). It is now common practice to place motion sensors on the waist of human subjects, but this site has limitations. In addition, advances in modern technology now allows tracking of both dynamic and static accelerations ( 8). As a result, these devices provide the opportunity to capture many more activities than uniaxial accelerometers thus, in comparison with uniaxial instruments, the output from triaxial devices tends to have higher correlations with energy expenditure ( 5, 7, 12). Triaxial accelerometers capture movement in the orthogonal planes. Prior to the development of triaxial accelerometers, uniaxial accelerometers were used to measure accelerations that occurred within the vertical plane ( 27). ![]() While pedometers are specifically designed to measure walking behaviors such as total steps taken per day ( 14), accelerometer-based physical activity monitors allow researchers to track frequency, intensity, and duration of activity ( 18). Movement sensors, such as pedometers and accelerometers, are inexpensive portable devices that allow researchers to objectively measure activity within the free-living environment ( 15). However, these methods are expensive, require trained professionals to administer, and are not practical for some applications ( 15). Doubly-labeled water, direct observation, and direct and indirect calorimetry are the most valid “criterion” measures of physical activity ( 27). The integrity of physical activity monitoring studies, intervention studies, and epidemiology studies rely on the valid and reliable assessment of physical activity ( 2). Since the mid-1980s there has been a steady increase in the evidence-based literature associating low levels of physical activity with an increased risk of chronic diseases such as type 2 diabetes, obesity, and cardiovascular disease ( 25).
0 Comments
Leave a Reply. |