Figure 1.

Validation protocol and primary results of validation. (A) Participants in the study were randomized into two groups. The first group (denoted by the downward-facing arrow at top) performed a gold standard VO₂max protocol and received training on day 1. The second group performed the two silver standard protocols concurrently with the smartphone protocols on day 1 (denoted by the upward-facing arrow at bottom). Both groups then performed the two smartphone protocols remotely up to three times during a 2-week period. (B) to (E) show Bland-Altman plots comparing the gold standard VO₂max with smartphone measures from: (B) 12-MRT performed in clinic, (C) 12-MRT performed remotely (up to 3 repeats per participant), (D) 3-MST in clinic, and (E) 3-MST remotely. VO₂max: maximal oxygen consumption; 3-MST: 3-minute step test; 12-MRT: 12-minute run test.