V La max: determining the optimal test duration for maximal lactate formation rate during all-out sprint cycle ergometry

Purpose
This study aimed to ascertain the optimal test duration to elicit the highest maximal lactate formation rate (VLamax), whilst exploring the underpinning energetics, and identifying the optimal blood lactate sampling period.

Methods
Fifteen trained to well-trained males (age 27 ± 6 years; peak power: 1134 ± 174 W) participated in a randomised cross-over design completing three all-out sprint cycling tests of differing test durations (10, 15, and 30 s). Peak and mean power output (W and W.kg−1), oxygen uptake, and blood lactate concentrations were measured. VLamax and energetic contributions (phosphagen, glycolytic, and oxidative) were determined using these parameters.

Results
The shortest test duration of 10 s elicited a significantly (p = 0.003; p < 0.001) higher VLamax (0.86 ± 0.17 mmol.L−1.s−1; 95% CI 0.802–0.974) compared with both 15 s (0.68 ± 0.18 mmol.L−1.s−1; 95% CI 0.596–0.794) and 30 s (0.45 ± 0.07 mmol.L−1.s−1; 95% CI 0.410–0.487). Differences in VLamax 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 30 s sprint duration was attained after 10 s. BLamaxpost were achieved at 5 ± 2 min (ttest 10 s), 6 ± 2 min (ttest 15 s), and 7 ± 2 min (ttest 30 s), respectively.

Conclusion
Our findings demonstrated a 10 s test duration elicited the highest VLamax. Furthermore, the 10 s test duration mitigated the influence of the oxidative metabolism during all-out cycling. The optimal sample time to determine peak blood lactate concentration following 10 s was 5 ± 2 min.