Abstract

Traditional life in the Canadian arctic presents major challenges to human adaptability because of the severe cold stress and the heavy physical work needed for survival. The impact of this habitat upon physical fitness and health has been reviewed in the context of a detailed study of an Inuit population living in the high arctic (69 degrees 40N) and undergoing rapid acculturation to a sedentary lifestyle. A traditional lifestyle was associated with a high aerobic power, above predicted lung function, strong leg muscles and very little subcutaneous fat. However, this was apparently an acute response to high daily energy expenditures rather than a genetic adaptation to the harsh environment, since the adaptation was lost with increasingly sedentary living. The same population was retested after 10 years, using the same methodology. There was a decrease of height in both young and older adults, a regression of aerobic power towards the values encountered in white society, and a substantial increase of skinfold thicknesses. Immediate lessons for the sports physician are: repeated exposure to intense cold is tolerated without permanent lung damage; sustained moderate exercise in the cold can induce a high level of aerobic fitness with very low levels of subcutaneous fat; prolonged snowmobile operation causes marked compression of intervertebral discs; and natural clothing can allow thermal equilibrium at temperatures as low as -40 degrees C. The loss of Inuit fitness with cultural change may also allow prospective investigation of the impact of a sedentary lifestyle upon the incidence of cardiovascular disease. Verf.-Referat