Peak Oxygen Uptake Among Healthy Adults: Cross-sectional descriptions and prospective analyses of peak oxygen uptake, physical activity and cardiovascular risk factors in healthy adults (20-90 years)

Abstract

Several publications have suggested that cardiovascular fitness is a key feature for longevity and a preferable health status, and the peak oxygen uptake (VO2peak) is suggested to be the most accurate assessment of overall cardiovascular fitness. There is, however, not a valid reference material for VO2peak from a general population, and the current thesis aimed to suggest such a material. In addition, we wanted to assess how directly measured VO2peak was associated with various conventional cardiovascular risk factors, and also across different levels of self-reported physical activity. Finally, we wanted to develop a non-exercise model for estimating VO2peak that was eligible in an outpatient scenario.

The Nord-Trøndelag Health Study (HUNT) has been conducted in Nord-Trøndelag, Norway, three times (1984-86, 1995-97, and 2006-08), with a versatile and increasing amount of data being collected at each survey. VO2peak was measured by direct ergospirometry in a sub-study on 4,631 healthy, adult subjects in HUNT3 (2006-08) called the HUNT Fitness Study.

We observed that 20-29 year old men and women achieved mean VO2peak-values of 54.0 mL·kg-1·min-1 (standard deviation, SD: 8.7) and 42.9 mL·kg-1·min-1 (SD: 7.6), respectively. A linear regression-analysis suggested a ~6% lower VO2peak per decade higher age in both genders. Across higher levels of categorized self-reported physical activity we observed that highly active 50-59 year old men and women had equal VO2peak to inactive 20-29 year old men and women. In a prospective analysis, we also observed that physical activity reported in HUNT1 (n=1,843 subjects) strongly predicted VO2peak in HUNT3 23 years later. The latter findings were novel. We also observed that VO2peak represented a continuum of overall cardiovascular health status where a 5 mL·kg-1·min-1 decrease in VO2peak was associated with ~56% higher odds of having a cluster of cardiovascular risk factors. Finally, our non-exercise models of VO2peak were fairly correct in classifying subjects into high- or low-fit categories (90% correct classification).