Reproducibility of heart rate at rest and in response to submaximal treadmill and bicycle ergometer test in middle-aged men

The reproducibility of heart rate at rest and in response to standardized ergometric tests on treadmill and bicycle was evaluated by test-retest. A series of sub-maximal tests were done on medically eligible middle-aged men at weekly intervals. The correlation (r) for successive sets of resting heart rates was in the range 0.72-0.78; mean differences were generally negligible. The r between successive exercise tests was higher (0.69-0.97). The mean of the second of a pair of tests was uniformly less by 1.0 to 3.4 beats/min than the mean of the first, and in about one-third of diese comparisons the mean difference was statistically significant. Standard Error of the Measurement and Technical Error between successive tests - measures of intra-individual variability - ranged from 2.0 to 6.7 beats/min, being less for treadmill than for bicycle or resting heart rate. Test reproducibility was similar at different loads of exercise. These data confirm that heart rates at rest and submaximal exercise are sufficiently stable characteristics of healthy middle-aged men to enable their use for longitudinal assessment of groups and individuals.