Blood lactate recovery and respiratory responses during diagonal skiing of variable intensity

The aims of the study were to investigate blood lactate recovery and respiratory variables during diagonal skiing of variable intensity in skiers at different performance levels. Twelve male cross-country skiers classified as elite (n=6; [Vdot]O2max=73±3 ml · kg−1 · min−1) or moderately trained (n=6; [Vdot]O2max=61±5 ml · kg−1 · min−1) performed a 48-min variable intensity protocol on a treadmill using the diagonal stride technique on roller skis, alternating between 3 min at 90% and 6 min at 70% of [Vdot]O2max. None of the moderately trained skiers were able to complete the variable intensity protocol and there was a difference in time to exhaustion between the two groups (elite: 45.0±7.3 min; moderately trained: 31.4±10.4 min) (P<0.05). The elite skiers had lower blood lactate concentrations and higher blood base excess concentrations at all 70% workloads than the moderately trained skiers (all P<0.05). In contrast, [Vdot] E/[Vdot]O2 and [Vdot] E/[Vdot]CO2 at the 70% [Vdot]O2max workloads decreased independently of group (P<0.05). Partial correlations showed that [Vdot]O2max was related to blood lactate at the first and second intervals at 70% of [Vdot]O2max (r=−0.81 and r=−0.82; both P<0.01) but not to [Vdot] E/[Vdot]O2, [Vdot] E/[Vdot]CO2 or the respiratory exchange ratio. Our results demonstrate that during diagonal skiing of variable intensity, (1) elite skiers have superior blood lactate recovery compared with moderately trained skiers, who did not show any lactate recovery at 70% of [Vdot]O2max, suggesting it is an important characteristic for performance; and (2) the decreases in respiratory exchange ratio, [Vdot] E/[Vdot]O2, and [Vdot] E/[Vdot]CO2 do not differ between elite and moderately trained skiers.