Comparison of kenz lifecorder versus actigraph physical activity output in free-living conditions

Background: The Kenz Lifecorder EX (KL) is a relatively new, moderately priced, user friendly accelerometer that tracks step counts and time spent in various intensity classifications. Thus, the KL is an attractive instrument for researchers and the public. However, there is limited research comparing the KL's output to other accelerometers during free-living conditions. Therefore the purpose of this study was to compare KL versus ActiGraph (AG) outputs of step counts and time spent in various intensity classifications during free-living conditions. Methods: Ten men and 10 women volunteers wore an AG (right side) and 2 KL (right side: KL-R vs. left side: KL-L) accelerometers on their waistline during waking hours for one day. Results: KL-R vs. KL-L yielded similar physical activity (PA) output. The AG recorded fewer steps compared with KL-L (P = .002) but was similar to the KL-R. The KL-R and KL-L yielded lower estimates of accumulated time spent in moderate PA compared with most AG intensity derivations (P < .003). There were no differences between KL-R and KL-L vs. the AG for time spent in vigorous PA. Conclusions: The KL provides similar estimates of step counts and time spent in vigorous PA compared with established AG intensity derivations.