Short-term modulation of the exercise ventilatory response in older men

During exercise with added dead space (DS), the exercise ventilatory response (ΔV˙E/ΔV˙CO2) is augmented in younger men, via short-term modulation (STM) of the exercise ventilatory response. We hypothesized that STM would be diminished or absent in older men due to age-related changes in respiratory function and ventilatory control. Men were studied at rest and during cycle exercise with and without added DS. ΔV˙E/ΔV˙CO2 increased progressively with increasing DS volume (p < 0.01), such that CO2 was not retained with added DS versus without. Hence, the increase in ΔV˙E/ΔV˙CO2 was not due to increased chemoreceptor feedback from rest to exercise. Increasing exercise intensity diminished the ΔV˙E/ΔV˙CO2 (p < 0.01), and the size of this effect varied by DS volume (p < 0.05). We conclude that STM of the exercise ventilatory response is robust in older men; hence, despite age-related changes in lung function and ventilatory control, the exercise ventilatory response can still adapt to increased DS, in order to maintain isocapnia during exercise relative to rest.