Effect of ramp slope on different methods to determine lactate threshold in semi-professional soccer players

The present study aimed to investigate the effect of stage duration in incremental protocols on lactate threshold (LT), determined by different methods. Sixteen semi-professional soccer-players performed a 4-min stage incremental discontinuous (DP) and two maximal incremental running continuous (1 km h−1· min−1, CP1; and 1 km h−1·2 min−1 CP2) protocols. Blood-lactate concentration [La−] was measured at baseline and during the protocols. LT was determined using DMAX, DMAX-MOD, 4-mM⋅L−1, Δ1-mM⋅L−1 and Log-Log methods. Log-Log showed no difference in LT between CP1, CP2 and DP. Conversely, LT was determined at higher velocity in CP1 than CP2 for DMAX (15.2 ± 0.5 vs 14.4 ± 1.2 km⋅h−1, P = 0.002), DMAX-MOD (16.0 ± 0.5 vs 14.7 ± 1.3 km⋅h−1, P < 0.001), 4-mM⋅L−1 (15.5 ± 1.4 vs 14.4 ± 1.2 km⋅h−1, P < 0.001), Δ1-mM⋅L−1 (15.5 ± 1.3 vs 14.4 ± 1.2 km⋅h−1, P < 0.001). Higher LT in CP1 than DP for DMAX (15.2 ± 0.5 vs 13.0 ± 1.0 km⋅h−1, P < 0.001) and DMAX-MOD (16.0 ± 0.5 vs 13.6 ± 1.6 km⋅h−1, P < 0.001) was found (P < 0.001). Log-Log resulted in shorter but accurate protocols to determine LT.