Ventilation threshold and aging.

The ventilation threshold (VeT) in 60 healthy men ages 22 to 65 years was determined on a maximal treadmill test. The VeT was identified as the highest VO2 before the ventilatory equivalent for oxygen began to increase without a corresponding increase in the ventilatory equivalent for carbon dioxide. The VO2 max was significantly lower in the 60 compared with the 20-year-old group (with age, r = -.81). The VeT was significantly lower in the oldest compared with the youngest group (with age, r = -.69); however, the VeT as a percentage of VO2 max was significantly greater in the oldest group, (with age, r = .37). The reserve capacity (VO2 max minus VeT) was significantly lower in the older men (with age, r = -.75) and was due to a greater reduction in VO2 max than in VeT. With multiple regression analysis, the variability in VeT was determined primarily by VO2 max (65.8%) and not age. Decrease in strenuous activity with age may account for the large reduction in VO2 max, whereas maintained submaximal activity may attenuate the reduction in VO2 at the ventilation threshold, thus resulting in a large loss in functional reserve above the level of the VeT.