Reference values for cardiorespiratory response and fitness on the treadmill in a 20- to 85-year-old population

Existing reference values for clinical exercise testing have been derived from small nonrandom samples, lacking women and older individuals and some with poor or no maximal end criteria. The objective was to study the cardiorespiratory response during maximal exercise in a representative predominantly Caucasian sample of men and women.

Nine hundred four randomly sampled men and women, 20 to 85 years old, exercised on a treadmill to exhaustion. Oxygen uptake (V.O2), heart rate (HR), BP, blood lactate concentration, and ventilatory variables were measured.

Seven hundred fifty-nine participants met the criteria for an acceptable maximal V.O2 (V.O2max) based on a respiratory exchange ratio≥1.10 or a Borg score≥17. In the 20- to 29-year-old age group, V.O2max (mL/kg/min) was 40.3 (±7.1) in women and 48.6 (±9.6) in men. A linear decline (8% per decade) was observed after age 30 years in both sexes. Maximal HR decreased with age by ±6.3 beats/min per decade. The maximal oxygen pulse was 33% lower in women and decreased significantly with age in both sexes by 5% and 3% per decade for women and men, respectively. Women's maximal ventilation was 66% that of men and decreased with age after 40 to 49 years in both sexes. Breathing reserve was higher and blood lactate was lower in women than in men.

This study establishes reference values for V.O2max (absolute, relative to body weight and fat-free weight), maximal HR, oxygen pulse, BP, ventilation, breathing reserve, respiratory exchange ratio, and blood lactate concentration during maximal exercise on treadmill in a large population.