Lamax: determining the optimal test duration for maximal lactate formation rate during all-out sprint cycle ergometry.

Abstract

This study aimed to ascertain the optimal test duration to elicit the highest maximal lactate formation rate ( Lamax), whilst exploring the underpinning energetics, and identifying the optimal blood lactate sampling period. Fifteen trained to well-trained males (age 27 ± 6years; peak power: 1134 ± 174W) participated in a randomised cross-over design completing three all-out sprint cycling tests of differing test durations (10, 15, and 30s). Peak and mean power output (W and W.kg-1), oxygen uptake, and blood lactate concentrations were measured. Lamax and energetic contributions (phosphagen, glycolytic, and oxidative) were determined using these parameters. The shortest test duration of 10s elicited a significantly (p = 0.003; p < 0.001) higher Lamax (0.86 ± 0.17mmol.L-1.s-1; 95% CI 0.802-0.974) compared with both 15s (0.68 ± 0.18mmol.L-1.s-1; 95% CI 0.596-0.794) and 30s (0.45 ± 0.07mmol.L-1.s-1; 95% CI 0.410-0.487). Differences in Lamax were associated with large effect sizes (d = 1.07, d = 3.15). We observed 81% of the PCr and 53% of the glycolytic work completed over the 30s sprint duration was attained after 10s. BLamaxpost were achieved at 5 ± 2min (ttest 10s), 6 ± 2min (ttest 15s), and 7 ± 2min (ttest 30s), respectively. Our findings demonstrated a 10s test duration elicited the highest Lamax. Furthermore, the 10s test duration mitigated the influence of the oxidative metabolism during all-out cycling. The optimal sample time to determine peak blood lactate concentration following 10s was 5 ± 2min.