Cardiorespiratory fitness in aging men and women: the DR's EXTRA study

The aim of the study was to describe the levels and to create reference values of cardiorespiratory fitness, expressed as maximal oxygen consumption (VO2max), maximal metabolic equivalents (METs) and maximal workload in aging men and women. We measured VO2max directly by a breath-by-breath method during a maximal exercise stress test on a bicycle ergometer with a linear workload increase of 20 W/min in a representative population sample of 672 men and 677 women aged 57-78 years. We presented the age and sex-specific categories of cardiorespiratory fitness (very low, low, medium, high and very high) based on variable distribution and non-linear regression models of VO2max, maximal METs and maximal workload. The linear age-related decrement of VO2max was -0.047 L/min/year (-2.3%) and -0.404 mL/kg/min/year (-1.6%) in men and -0.027 L/min/year (-1.9%) and -0.328 mL/kg/min/year (-1.6%) in women. After exclusion of diseased individuals, the rate of VO2max decrement remained similar. The number of chronic diseases (0, 1, 2 or >= 3) was inversely associated with VO2max in men (P < 0.001) and women (P < 0.001). The present study provides clinically useful reference values of cardiorespiratory fitness for primary and secondary prevention purposes in aging people.