Energy cost of and energy sources for alpine skiing in top athletes.

O2 uptake (VO2) during exercise and at 2 min of the recovery along with blood lactate concentration 5 min after exercise were measured in an all-out special slalom (SS) and giant slalom (GS) performed by eight top male athletes and five controls in a field study. Heart rate (HR) was continuously monitored before, during, and after each task. On the basis of an energy equivalent of 3.15 ml O2 X kg body wt-1 for 1 mmol X 1-1 lactate accumulation and the assumption that the amount of O2 consumed in recovery is used to reconstitute approximately phosphates used during the exercise, the total energy cost (delta VO2 tot) could be calculated and subdivided into aerobic, lactic, and alactic fractions. In top athletes, delta VO2 tot was equal during SS and GS [7.28 +/- 1.14 (SD) and 7.47 +/- 0.89 liters for about 55- and 70-s performances, respectively]. When referred to time, the O2 expenditure rate was 2 and 1.6 times VO2max in SS and GS, respectively. In SS and GS, the energy sources were about 40% aerobic, 20% alactic , and 40% lactic metabolism. In control skiers, delta VO2 tot of GS was 6.12 +/- 1.45 liters for 77 s, amounting to about 1.3 VO2max, with the contribution of the different energy sources being roughly the same as in top skiers. HR reached maximal values in 30-40 s in all subjects for all conditions.