Reduced cardiovascular mortality at moderate altitude: a putative role of physical activity and body mass

Epidemiological evidence suggests that living at a moderate altitude (i.e. between 1000 and 2500 m) is associated with lower overall mortality, particularly from cardiovascular diseases. The underlying mechanisms have been scarcely investigated, although environmental and lifestyle factors likely play prominent roles. This review aims to shed light on two important modulators of cardiovascular health and mortality, that is, physical activity and body mass, and to explore how these factors interact with altitude. The lifestyle habits of people living at moderate altitudes have been shown to differ from individuals living at low altitudes. In addition the environmental conditions, notably the hypobaric hypoxia, at moderate altitudes influence the physiological parameters associated with these habits. Specifically engaging in the same physical activity at moderate altitude compared to low altitude results in enhanced cardiovascular responses and specific metabolic responses, potentially imparting benefits related to the cardiovascular system and body composition. Conversely mild hypobaric hypoxia can suppress appetite and food intake, leading to lower overall body mass and decreased risk of obesity. Exercise or sleep can accentuate the hypoxic stimuli at moderate altitudes and, like hypoxia conditioning, elicit adaptations such as improved oxygen supply, reduced dependence on oxygen and increased cellular/tissue resilience. These effects may prove beneficial for the cardiovascular and metabolic systems and contribute to lower mortality rates observed in moderate altitude residents.