Blood lactate and respiratory variables in elite cross‐country skiing at racing speeds

The purpose of this study was to examine energy metabolism during two simulated races (skating and classical) in cross‐country skiing. In each race 15 elite subjects skied a 2.75‐km track 5 times. In laps 2 and 4, the skiers were told to skate without poles in the skating race and without the diagonal stride in the classical race. The total exercise time was between 42 and 50 min in the 2 races. The oxygen uptake was measured on flat and uphill terrain during each lap and blood lactate after each lap. The relative mean oxygen uptake for classical skiing was 88% (82‐96) for level and 93% (87‐97) for uphill terrain. The respective means for skating were 91% (85‐96) for level and 91% (81‐97) for uphill terrain. The mean values and range for blood lactate at race speeds were 10.6 mM (7.1‐18.1) and 9.2 mM (4.8‐18.8) for skating and classical, respectively. A relative steady state was achieved after the first lap, although a slight but significant blood lactate accumulation took place until finish (0.04‐0.06 mM min −1 ). The respiratory exchange ratio in both skiing styles varied between 0.88‐0.90 and 0.92‐0.93 for flat and uphill terrain, respectively, indicating a large lipid oxidation at these very high exercise intensities.