THE INFLUENCE OF TESTING MODALITY ON LACTATE THRESHOLD AND THE VELOCITY ASSOCIATED WITH VO2MAX.

Aim: The velocity associated with maximum aerobic power (vVO2max) and lactate threshold (LaT) are important physiological parameters, which are utilized to determine relative workloads on the field. The testing modality adopted to evaluate it, though, may cause differences in vVO2max and LaT assessment and, in turn, in training intensity. Long distance runners (RUN) and soccer players (SOC) are both athletes involved with running. However, the physiological demands are different: in RUN are continuous while in SOC are discontinuous, with an alternation of aerobic and anaerobic tasks. Therefore, the aim of the studies was to compare two different testing modalities (continuous incremental ramp and discontinuous square wave (SW) protocols) for vVO2max assessment on the treadmill in physically active male, RUN and SOC. Hypothesis is that due to the faster increase in running velocity with time, vVO2max would be higher in the continuous incremental ramp tests compared to SW and this difference should be higher in SOC than in RUN, due to a different capacity to adjust the oxygen transport system at each workload. Moreover, we studied how the slope of the increase in running velocity with time (ramp slope) during continuous incremental ramp protocol, though, may affect LaT assessment measured with different methods. Methods: Seventeen physically active participants, eight RUN and nine SOC performed three maximum incremental tests on a treadmill: two continuous ramp protocols, with different ramp slopes (R1, 1 km·h-1 per min; and R2, 1 km·h-1 every 2 min), and one discontinuous SW protocol, in random order, for maximum oxygen uptake (VO2max) and vVO2max determination. Cardiorespiratory and metabolic parameters were collected breath-by-breath at rest and during exercise. Blood lactate concentration [La-]b was measured at rest, during, and at peak exercise. In both protocols, LaT was calculated by DMAX, DMAX MOD, 4 mM, Δ1 mM and Log-Log methods. Results: vVO2max was significantly higher in R1 and R2 compared to SW (16.8±0.6, 20.7±0.5, 18.6±0.4 km·h-1 for SW, R1, R2, respectively; P<0.001). No significant differences were found among protocols for VO2max (4018±111, 4039±110, 4003±100 ml·min-1 for SW, R1, R2, respectively) as well as for expiratory ventilation, carbon dioxide production, blood lactate concentration, and heart rate. In the second study, no significant differences between groups and protocols were found in VO2max as well as in VE, VCO2, [La-]peak and HR at maximum exercise. However, vVO2max was significantly higher in R1 and R2 compared to SW in SOC, while only R1 was significantly higher than SW in RUN. A higher difference between R1 vs SW and in R2 vs SW was found in SOC than RUN for both ramps (+29% and 16% vs SW for R1 and R2 in SOC and +16% and 6% vs SW for R1 and R2 in RUN). Moreover, LaT had higher velocities in R1 for DMAX (16.5±0.4 vs 15.1±0.4 km⋅h-1, P=0.002), DMAX MOD (17.7±0.5 vs 15.6±0.4 km⋅h-1, P<0.001), 4 mM (17.0±0.6 vs 15.5±0.5 km⋅h-1, P<0.001), Δ1 mM (17.1±0.5 vs 15.1±0.4 km⋅h-1, P<0.001), but not for Log-Log. Conclusion: In spite of similar VO2max values, vVO2max was higher during continuous incremental ramp tests compared to SW due to the longer time for cardiorespiratory and metabolic adjustments, suggesting different aerobic and anaerobic metabolism involvement. However, the difference was significantly higher in SOC than RUN, possibly due to a slower capacity to adjust the oxygen transport system to a given workload in SOC. Even though the three protocols can be used to assess VO2max, the vVO2max differences between protocols must be acknowledged to prescribe correctly high intensity training, especially for soccer players. Lastly, the testing modality influenced also LaT assessment. Indeed, with the only exception of Log-Log, all the other methods presented significantly higher velocities at LaT when the steeper ramp slope (R1) was utilized.