Validity of the Apple Watch® for monitoring push counts in people using manual wheelchairs

The study evaluates how well the Apple Watch tracks the number of wheelchair pushes in manual wheelchair users. It compares the watch's push count to direct observation. The Apple Watch® push count estimates are acceptable for personal, self-monitoring purposes and for research entailing group-level analyses, but less acceptable where accurate push-count measures for an individual is required. This information can help manual wheelchair users monitor their physical activity levels and assist researchers in evaluating exercise programs.

• 1
  Apple Watch® push counts and directly observed pushes were strongly correlated (ICC = 0.77, P < 0.01) (r = 0.84, P < 0.01).
• 2
  Bland Altman plots indicated that the Apple Watch® underestimated push counts (M = −103; 95% ULoA = 217; LLoA = −423 pushes).
• 3
  Mean absolute percentage error was 13.5% which is comparable to studies evaluating agreement between pedometer-based step counts and directly observed steps.