Influence of ageing on aerobic parameters determined from a ramp test.

The purpose of this study was to examine the four parameters of aerobic function, the maximum oxygen uptake (VO2max), ventilation threshold (ThVE), efficiency, and the effective time constant for oxygen consumption (tau'VO2), across age. In particular, the study was designed to observe whether there may be accelerated declines in aerobic function beyond 60 years of age. Seventy-nine sedentary men aged 30-84 years were studied. Each subject performed two maximal cycle ramp function tests, and data were collected on a breath-by-breath basis. The VO2max, from a plateau in VO2, was achieved in 87% of the subjects using the ramp test. The VO2max showed a significant decrease with increasing age (from linear regression, r = -0.81) at a rate averaging 0.037 l.min-1.year-1. The ThVE also declined with increasing age, but at a slower rate (0.013 l.min-1.year-1). The tau'VO2 was significantly increased across the age groups from 69 s for those aged 30-40 years to 98 s for those aged 60 years or more. There was no evidence of accelerated decline in these aerobic parameters beyond age 60 years, and there were no differences in efficiency (27.5-29.9%) across age. Although other forcing functions should be used to confirm this characterization of the oxygen kinetics, this slowed response with age would result in greater oxygen deficit and possibly earlier fatigue in response to even light exercise in older individuals.