Some consequences of polar stress: data from a transpolar ski-trek.

Findings from the recent Canadian/Soviet transpolar skitrek are reviewed. Comparison of field heart rate measurements with laboratory data suggests a high rate of energy expenditure over the trek; the 13 participants covered some 20 km/day at a speed of about 3.5 km/h, while carrying 37-45 kg packs. Strength increased and body fat decreased over the journey, but aerobic power data showed an anomalous decline, possibly related in part to intensive pre-trip training and an increase of skiing efficiency during the trek. Two of the 13 participants suffered sufficient local cold exposure to develop significant frostbite, and all had sufficient cold exposure to show some general cold acclimatization. Eight of the 13 also suffered from excessive ultraviolet exposure. The main psychological problems were related to inter-personal conflicts and difficulties of communication between the two teams. Hormonal changes were extensive, but generally in line with expectations for a combination of vigorous exercise, cold exposure and psychological stress. Nutritional responses reflect a high rate of fat usage, with a significant increase of HDL-cholesterol levels. It is concluded that well-trained young and middle-aged adults from an urban environment can participate in a well-planned and prolonged arctic winter traverse without serious adverse effects on either physiological or psychological systems.