Physiological variables in the HUNT 3 Fitness study stratified by sex and age groups.

Data is presented as arithmetic mean ± SD. VO2max: maximal oxygen uptake, EqVO2max: ventilatory equivalents, R: respiratory exchange ratio, fc: cardiac frequency, Workload: treadmill exercise load, BORG: subjective perception of fatigue (6–20), PAI: physical activity index: A weighted product score between training- intensity, duration and frequency.