Plasma cathecolamines and nucleotide-related purine bases during mountain climbing

Climbing is a high-expenditure sport, consisting of aerobic and anaerobic exercise, performed at variable strain, sometimes for a long time. We aimed at defining the physiological changes to mountain climbing, related both to physical strain and acute hypoxia, and the effects on human muscle energy balance, by measuring cathecolamine and oxypurine levels. Eight male well-trained climbers, not acclimatized to altitude, were studied during a mountain climbing between 2240 and 2500 m. Climbers were divided in pairs according their skill and ascended the 1st Torre del Sella through four different routes. Blood samples were drawn at definite times in the morning, before breakfast, on top of the mountain, and at the end of the exercise, after descent. Basal norepinephrine and epinephrine were high-normal and increased by 50-100% in response to exercise; dopamine did not change. Also hypoxanthine and xanthine increased during exercise, and correlations were found between exercise-induced norepinephrine and hypoxanthine. Lactate increased but did not reach the anaerobic threshold value. Ammonia and uric acid were normal and did not change. Changes in cathecolamine and oxypurine levels appear to be more related to exercise-duration more than strain intensity. Data support a major role of relative hypoxia.