INTRODUCTION: Laboratory testing of competitive alpine ski racers generally lack specificity of modalities that are appropriate and are difficult to emulate in laboratory environment. On-snow physiological field tests are seldom conducted and we generally lack results that are comparable or specific for alpine ski racing. Most laboratory tests of different duration and different resistances, various fest batteries, and ergometry tests, have been utilized in the past with little or no relationship to actual alpine ski racing event. METHOD: We measured respiratory gas exchange (RGEM) via portable metabolic System in breath-by-breath mode at -8 C° during the on-snow giant slalom training runs of 60s in 13 young male ski racers and compared these with 2 distinctly different VO2max treadmill tests (TT-1 and TT-2) conducted in the laboratory. In addition we measured heart rate (HR) and blood lactate concentration (LA) to determine differences between laboratory and field tests. Test 1 (TT-1) was an incremental VO2max test and Test 2 (TT-2) was a test to determine maximal time a ski racer could sustain at maximal speed measured during TT-1. RESULTS: Statistical analysis revealed that on average ski racers sustained maximal performance speed for 3.64 min, resulting in VO2max of 54.9+3.8 in TT-2 vs. 55.8+3.6 ml.kg-1.min-1 (P>0.05) measured in TT-1. There were significant differences between VO2max measured in TT-1 and min 1, 2, 3, 4, of the TT-2 (P<0.001). There were no Statistical differences for LA between the two tests; however, there were Statistical differences for HR measured during TT-1 and HR measured during min 1, 2, 3, and 4 of maximal performance in TT-2. During on-snow GS training runs the mean VO2 was 27.7+3.5 with peak VO2 of 33.7 ml.kg-1.min-1 (p<0.001) resulting in 50.3% reduction measured in TT-1 and 49.5% for TT-2. Peak VEBTPS during on-snow GS training runs was 100.3 l.min"1 corresponding to 35.3% reduction in TT-1 and 31.5% in TT-2 (p<0.001). There were no significant differences for LA between the TT-1 and TT-2, however, there were significantly lower values for LA between laboratory tests and LA measured at the end of on-snow GS training runs (p0.001). DISCUSSION: Karlsson et al. (1978) reported a mean VO2 of 67-68 ml.kg-1.min-1 or mean VO2 of 4.79 l.min-1 for members of the Swedish National Ski Team during laboratory testing for years 1974-76. Karlsson et al. (1978) also measured VO2 uptake (Douglas bag method) during 85s training runs in 3 racers who completed several training runs. Mean VO2 uptake for 8 runs was 3.6 l.min"1 white the mean VO2max for the 3 racers was 4.1 l.min-1 or 88% of their VO2max. Karlsson et al. (1978) also reported VO2 value ranges between 73-87% of racers VO2max. In our on-snow training study, ski racers performed at ~50% of their VO2max measured in the laboratory. LA levels were equally well below 50% of their laboratory tests. We contribute these differences mostly to reduced metabolic demand due to improvement in ski equipment, short bout of ski racing event (60s), moderate skiing intensity, specificity of the event, and comfort level of ski racing to name a few. CONCLUSION: Our results suggest that well trained ski racers can indeed sustain maximal performance twice the length of their competitive event. When comparing laboratory to field results, the on-snow results yielded much lower metabolic and profound non-steady state respiratory response well below that of laboratory results.
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