Purpose: Assessing cardiopulmonary function during swimming is a complex and cumbersome procedure. Backward extrapolation is often used to predict peak oxygen uptake (VO2peak) during unimpeded swimming, but error can derive from a delay at the onset of VO2 recovery. The authors assessed the validity of a mathematical model based on heart rate (HR) and postexercise VO2 kinetics for the estimation of VO2peak during exercise.
Methods: 34 elite swimmers performed a maximal front-crawl 200-m swim. VO2 was measured breath by breath and HR from beat-to-beat intervals. Data were time-aligned and 1-s-interpolated. Exercise VO2peak was the average of the last 20 s of exercise. Postexercise V˙O2 was the first 20-s average during the immediate recovery. Predicted VO2 values (pVO2) were computed using the equation: pVO2(t) = VO2(t) HRend-exercise/HR(t). Average values were calculated for different time intervals and compared with measured exercise VO2peak.
Results: Postexercise VO2 (0-20 s) underestimated VO2peak by 3.3% (95% CI = 9.8% underestimation to 3.2% overestimation, mean difference = -116 mL/min, SEE = 4.2%, P = .001). The best VO2peak estimates were offered by pVO2peak from 0 to 20 s (r2 = .96, mean difference = 17 mL/min, SEE = 3.8%).
Conclusions: The high correlation (r2 = .86-.96) and agreement between exercise and predicted VO2 support the validity of the model, which provides accurate VO2peak estimations after a single maximal swim while avoiding the error of backward extrapolation and allowing the subject to swim completely unimpeded.