Ageing and cardiorespiratory response to hypoxia

Key points A previous study showed that an older age could be associated with a lower risk of severe altitude‐induced diseases. This work combines a cross‐sectional study including 4675 subjects and a longitudinal study on 30 subjects. It shows that ageing is associated with a blunting of cardiac chronotropic function and an increase in ventilatory response leading to maintenance of arterial O 2 saturation in hypoxia. These adaptive responses to hypoxia with ageing are blunted by menopause but can be maintained with endurance training. The cardiac and ventilatory adaptations allow older people to challenge hypoxia similarly to younger ones when performing moderate exercise. Abstract  The risk of severe altitude‐induced diseases is related to ventilatory and cardiac responses to hypoxia and is dependent on sex, age and exercise training status. However, it remains unclear how ageing modifies these physiological adaptations to hypoxia. We assessed the physiological responses to hypoxia with ageing through a cross‐sectional 20 year study including 4675 subjects (2789 men, 1886 women; 14–85 years old) and a longitudinal study including 30 subjects explored at a mean 10.4 year interval. The influence of sex, training status and menopause was evaluated. The hypoxia‐induced desaturation and the ventilatory and cardiac responses to hypoxia at rest and exercise were measured. In men, ventilatory response to hypoxia increased ( P < 0.002), while desaturation was less pronounced ( P < 0.001) with ageing. Cardiac response to hypoxia was blunted with ageing in both sexes ( P < 0.001). Similar results were found in the longitudinal study, with a decrease in cardiac and an increase in ventilatory response to hypoxia with ageing. These adaptive responses were less pronounced or absent in post‐menopausal women ( P < 0.01). At exercise, desaturation was greater in trained subjects but cardiac and ventilatory responses to hypoxia were preserved by training, especially in elderly people. In conclusion, respiratory response to hypoxia and blood oxygenation improve with ageing in men while cardiac response is blunted with ageing in both sexes. Training aggravates desaturation at exercise in hypoxia, improves the ventilatory response and limits the ageing‐induced blunting of cardiac response to hypoxia. Training limits the negative effects of menopause in cardiorespiratory adaptations to hypoxia.