Reliability of the assessment of the oxygen/heart rate relationship during a workday

The purpose of the present study was to evaluate the reliability of the oxygen consumption/heart rate (VO2/HR) relationship used to estimate energy expenditure during a workday. Before and after a 6–10 h work shift, the VO2/HR relationship was measured in 57 workers (28 female, 29 male) in our laboratory. VO2 was similar before and after the shift at HR of 100 and 125 beats per minute (bpm). However, the VO2/HR relation and perceived exertion (RPE) became less accurate after a work shift as VO2 and RPE were, respectively, increased at HR above 150 and 125 bpm. Increase of RPE for a same exercise intensity was higher in female subjects. Our results suggest good reliability of the VO2/HR relationship at HR usually found in workplaces.