Decompression sickness and the role of exercise during decompression.

The risk of decompression sickness (DCS) is greatly increased with exercise at altitude. Bends is the commonest symptom in altitude DCS. Though the adverse effect of exercise at altitude is well known, the role of exercise during decompression is not clear. In this paper, a case of bends occurring with exercise during accidental decompression is presented. The event occurred while exercising on a treadmill at an altitude of approximately 4,572 m (15,000 ft) in the hypobaric chamber. No oxygen pre-breathe was done and ambient air was breathed throughout. The role of hypoxia and exercise during decompression, as well as individual susceptibility, are discussed. Even moderately severe exercise at low altitude may predispose healthy individuals breathing ambient air to DCS, especially when exercise is undertaken during decompression.