Validation of a submaximal versus a maximal exercise test in obese individuals

This is the authors' abstract. We don't add key points for this paper.

The purpose of this study was to compare oxygen uptake estimated from submaximal Åstrand tests (VO2est) with measured peak oxygen uptake (VO2peak) from maximal tests, and to compare estimated maximal HR (HRest) with measured HRpeak in obese subjects. Seventy obese subjects performed a maximal exercise test starting with a 4-min period of constant load. VO2peak and HRpeak were measured. VO2est was based on HR at constant load. HRest was calculated by the formula 220 − age. The mean± SD of VO2est 2.05 ± 0.39 l/min (20 ± 5 ml/kg/min) was lower than VO2peak 2.42 ± 0.57 l/min (17 ± 4 ml/kg/min) (p < 0.001, p < 0.001, respectively). The mean difference ± 2SD was − 0.4 ± 1.22 l/min (− 3 ± 10 ml/kg/min) with an uneven distribution of the individual variation. The correlation between the methods was low (r = 0.24, r = 0.38 respectively). The mean± SD of HRest 176 ± 10 bpm was higher than the HRpeak 161 ± 17 bpm (p < 0.001). The mean difference ± 2SD was 15 ± 31.3 bpm with an uneven distribution of the individual variation. The correlation between the methods was low (r = 0.41). The main findings of this study were that estimation of VO2 from the Åstrand test and of HR by the formula 220 − age had low validity in obese subjects. Consequently, direct measurements of HRpeak and VO2peak are recommended for accurate prediction of obese individual's exercise capacity.

Submaximal Åstrand estimates warrant caution in obese patients; leaves open need for targeted validation before routine use.