Anaerobic Speed Reserve and Critical Speed as Predictors of 200 m Front Crawl Performance: A Practical Alternative to...

Anaerobic speed reserve (ASR) and critical speed (CS) offer practical, performance-based estimates of physiological tolerances, and can be derived from maximal aerobic speed (MAS) and maximal sprint speed (MSS) in swimming. We evaluated the predictive capabilities of ASR and CS for 200 m front crawl performance in trained swimmers, and whether the addition of physiological markers could improve model accuracy. Seventeen trained male (n = 8) and female (n = 9) swimmers completed three maximal front crawl time-trials (50, 200, and 400 m) on different days, with 50 m (MSS) and 400 m (MAS) used to determine ASR and CS. Blood gas variables, blood lactate concentration (BLa), peak oxygen consumption (VO_2peak), blood bicarbonate concentration (HCO₃), and blood pH were measured pre- and post-trial. Linear regression models were developed, with multivariate analysis of variance assessing the impact of distance on all variables. MSS was the best predictor of 200 m performance (R² = 0.83), followed by CS (R² = 0.69), whereas ASR provided moderate predictive capabilities (R² = 0.36). The addition of CS to MSS provided our strongest two-factor model (R² = 0.93), decreasing mean absolute error (MAE) from 2.41 to 1.62 s, closely followed by MSS + ASR (R² = 0.92, MAE = 1.74 s). Physiological markers of aerobic (VO_2peak: r = 0.44, p > 0.05) and anaerobic capacity (ΔHCO₃: r = 0.54; ΔpH: r = 0.48; and ΔBLa: r = 0.57, all p < 0.05) were only moderately correlated with 200 m front crawl performance, and didn't meaningfully improve regression models. MSS provided the highest prediction of 200 m times, whereas ASR and CS provide practical alternatives to the collection of physiological variables which further distinguish performance potential in swimming cohorts.