A Prospective Population Study of Resting Heart Rate and Peak Oxygen Uptake (the HUNT Study, Norway)

Objectives: We assessed the prospective association of resting heart rate (RHR) at baseline with peak oxygen uptake (VO_2peak) 23 years later, and evaluated whether physical activity (PA) could modify this association. Background: Both RHR and VO_2peak are strong and independent predictors of cardiovascular morbidity and mortality. However, the association of RHR with VO_2peak and modifying effect of PA have not been prospectively assessed in population studies. Methods: In 807 men and 810 women free from cardiovascular disease both at baseline (1984-86) and follow-up 23 years later, RHR was recorded at both occasions, and VO_2peak was measured by ergospirometry at follow-up. We used Generalized Linear Models to assess the association of baseline RHR with VO_2peak, and to study combined effects of RHR and self-reported PA on later VO_2peak. Results: There was an inverse association of RHR at baseline with VO_2peak (p<0.01). Men and women with baseline RHR greater than 80 bpm had 4.6 mL·kg^-1·min^-1 (95% confidence interval [CI], 2.8 to 6.3) and 1.4 mL·kg^-1·min^-1 (95% CI, -0.4 to 3.1) lower VO_2peak at follow-up compared with men and women with RHR below 60 bpm at baseline. We found a linear association of change in RHR with VO_2peak (p = 0.03), suggesting that a decrease in RHR over time is likely to be beneficial for cardiovascular fitness. Participants with low RHR and high PA at baseline had higher VO_2peak than inactive people with relatively high RHR. However, among participants with relatively high RHR and high PA at baseline, VO_2peak was similar to inactive people with relatively low RHR. Conclusion: RHR is an important predictor of VO_2peak, and serial assessments of RHR may provide useful and inexpensive information on cardiovascular fitness. The results suggest that high levels of PA may compensate for the lower VO_2peak associated with a high RHR.