Measuring the validity and reliability of the Apple Watch as a physical activity monitor.

BACKGROUND

This study aimed to investigate the validity and reliability of the energy expenditure (EE) estimation of Apple Watch® among college students.

METHODS

Thirty college students completed two sets of three 10-minute treadmill walking and running trials while wearing three Apple watches and being connected to indirect calorimetry. The walking trials were at speeds of 54, 80, and 107 m·min-1 while the running trials were at 134, 161, 188 m·min-1. Energy expenditure comparisons were made using Two-way ANOVA with repeated measures. Reliability was analyzed by Intraclass Correlation.

RESULTS

There was no significant device x speed interactions (F (15, 696)=1.113, P=0.341) between the indirect calorimetry (criterion) and Apple Watch®. The lowest Inter-Class Correlation (ICC) scores were 0.49 (95%CI) at 54 while the highest were 0.72 (95%CI) at 107 and 134 m·min-1.

CONCLUSIONS

Apple Watch® demonstrated a low to moderate validity and reliability on measuring EE.