A Comparison of the Ventilatory Responses to Exercise of Elderly and Younger Humans

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Abstract
Elderly adults are assumed to have an exaggerated ventilatory response to exercise. This study sought to examine this assumption by comparing the steady-state ventilatory and gas exchange responses of a group of elderly and younger humans. Steady-state ventilatory responses to moderate cycle ergometer exercise were measured in 14 elderly (71.0 ± 1.3, mean ± SEM years) and 14 younger (21.8 ± 0.7 years) subjects. Compared with the younger group, the elderly had a significantly higher V̇E,−V̇CO2, and V̇O2 at all work rates. In addition, ΔV̇E/ΔV̇CO2 was significantly higher for the elderly than for the younger subjects (31.07 ± 1.34 vs 27.16 ± 1.01, respectively; p < .03), but the intercept with the ventilation axis was significantly lower (0.81 ± 0.97 l.min−1 vs 4.15 ± 0.77 l.min−1, respectively; p < .015). Consequently, the V̇E−V̇CO2 relationships of the two groups crossed and the ventilatory equivalent for CO2 was similar for both groups. Thus, in these elderly subjects, the steeper ΔV̇E/ΔV̇CO2 was misleading because it was not associated with a greater ventilatory equivalent for CO2. In summary, although the ventilatory response of these elderly subjects to a given work rate was greater than that of the younger subjects, this was secondary to a greater metabolic requirement and cannot therefore be considered exaggerated. Furthermore, the data suggest that V̇E/V̇CO2 may be an inappropriate index of the ventilatory response to exercise in the elderly

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