Background/Purpose The cost of accelerometers used to monitor physical activity has been substantially reduced over the past few years, however, the validity of inexpensive units such as the $20 Movband™ has yet to be investigated. This study examined the convergent validity of the Movband™ activity monitor with the NL-2000 accelerometer. The NL-2000 was chosen as the criterion unit because it is unaffected by BMI, pedometer tilt, or waist circumference, and has been recommended for use in research (Crouter, Schneider, Karabulut, & Bassett, 2003).
Method One hundred and eleven elementary school aged children (53 boys, 58 girls; 9.2 ± 0.7 yr) from three physical education classes wore an NL-2000 on their right hip and a Movband™ on each wrist during a 30 minute physical education class in which participants walked or ran on a hiking trail.
Analysis/Results When compared to the NL-2000, the Movband™ tended to underestimate steps (left= 8.57% ± 3.23%; right= 8.79% ± 2.94%). A repeated measures ANOVA of mean steps indicated a significant difference (p< .001) between the NL-2000 (2411.74 ± 514.87) and the Movband™ worn on either wrist (left= 1554.33 ± 340.81, right= 1532.26 ± 329.76). Pearson product-moment correlations indicated that NL-2000 steps and Movsteps™ were significantly and positively correlated (p< .001; left= .79, right= .85). The correlation coefficient between left and right wrists was .87.
Conclusions In general, the Movband™ can provide reasonable estimates of physical activity for practitioners. Future research should examine the validity of low-cost accelerometers to estimate miles and moderate-to-vigorous physical activity time.