Validation of the PiezoRx® Step Count and Moderate to Vigorous Physical Activity Times in Free Living Conditions in Adults: A Pilot Study

The purpose of the study was to: 1) Validate the PiezoRx® for steps and intensity related physical activity in free-living conditions compared to the criterion measure. 2) Compare PiezoRx®’s steps and intensity related physical activity to physiological assessments. 3) To assess the utility of the PiezoRx® in a subsample of participants. Thirty-nine participants consisting of 28 females aged 54.9±10.6 (33–74) years and 11 males aged 63.9±10.9 (44–80) years wore the PiezoRx® physical activity monitor and the ActiGraph® accelerometer for one full week and completed a physical assessment. A subsample (n=24) wore the PiezoRx® for an additional two weeks and completed a questionnaire regarding usability. The PiezoRx® had strong correlations to the ActiGraph® for step count (r=0.88; p<0.001), moderate-vigorous physical activity (MVPA) (r=0.70; p<0.001), and sedentary activity (r=0.93; p<0.001) in the 1-week monitoring period. The PiezoRx®’s steps/day and MVPA/week were negatively correlated (p<0.001) to body mass index and waist circumference, and positively correlated (p<0.05) to aerobic fitness, pushups, and 30 second sit-to-stand. Within the subsample who completed the additional two-week monitoring, 75% of participants reported that the PiezoRx® increased their physical activity. In conclusion, The PiezoRx® appears to be a valid measure of free-living PA compared to accelerometry. Because of the correlations of the PiezoRx®’s steps/day and MVPA/week to anthropometric, musculoskeletal and aerobic fitness these PA measures may be valuable objective surrogates to use in clinical or professional practice for physical health.