In the first science Conference on skiing here in St Christoph a four-decade perspective was presented on the physiology of cc skiing. The major development in that time period was the enlarged reliance of the upper body in cc skiing; not only in the free style (skating), but in the classical (diagonal) technique as well. This has led to a series of investigations of the upper body in cc skiing, using invasive techniques both to study the metabolic and the cardiorespiratory responses. METABOLISM The arterial lactate concentration can in competition average well above 5 mmol/l. It is the arm/should muscles being the primary provider of this lactate. There is a continuous release of lactate from this region throughout prolonged skiing, while the leg takes up a substantial fraction of this lactate and use it as a fuel thereby markedly inhibiting lactate to accumulate in the blood to astronomic levels. In spite of the high lactate production in the arms there is not only a high aerobic use of pyruvate but also of fat oxidation, although the latter being less in the arms than in the legs. Any good explanation for the difference between arm-shoulder compared with leg muscles in regard to the lactate metabolism is not at hand, but is likely to be a function of the regulation of the glycolysis rather than structural or metabolic capacity of the various muscles in the upper compared with the lower body. CIRCULATION The close match between 02 consumed to blood flow is kept in all techniques in cc skiing and in principle also for upper and lower body, ie. there is 5 l/min of blood flow per litre of oxygen consumed. The heart rate - stroke volume relationships are also similar regardless of technique and of which part of the body that contributes the most to the exercise intensity/velocity. What was also found was further support for the pump capacity of the hart being the true limiting factor. Peak muscle biood flow in arms and legs could not be reached in a maximal effort combining upper body muscles, torso and lower body muscles (classical technique). ARTERIAL OXYGEN SATURATION Endurance athletes are said to desaturate when exercising hard. This only occurs to a very minor extent in cc skiing and is primarily explained by a shift in pH. The Va/Vo2 ratio is high when skiing but it cannot be the explanation. The question has arisen whether the movement of the upper body may improve the ventilation/perfusion ratio, which in addition to an effective venous return optimizes pulmonary function in cc skiing. In conclusion it is worth referring to A.V Hill who once stated that studies on exercising humans open for unravelling the secrets of the regulatory mechanisms that make man such a good athlete.
© Copyright 2007 4th International Congress on Science and Skiing. Veröffentlicht von University of Salzburg. Alle Rechte vorbehalten.