Reliability and validity of the Åstrand nomogram for submaximal VO2max estimation

Submaximal treadmill estimation of VO2max using the Bruce protocol. The paper compared linear extrapolation of submaximal heart-rate data to the Åstrand nomogram. Linear extrapolation (the method the authors recommend) achieved ICC 0.9433 — comparable to the reliability of measured VO2max itself — with a mean bias of only −1.1 ml·min⁻¹·kg⁻¹ (2.19% underestimate). Moderate.