The impact of propranolol on the predictive validity of estimated VO2 max by the Ekblom-Bak submaximal cycle test: a double-blind crossover study

Abstract

Purpose: Usage of beta-blockers may influence heart rate response during exercise testing. The study aimed to investigate the impact of Propranolol, a non-selective beta-blocker, on the predictive validity of a commonly used submaximal cycle test, the Ekblom-Bak test (EB-test), for the estimation of maximal oxygen uptake (V O 2 max). Methods: The study was a double-blinded crossover study including 28 participants (14 women), aged 21–59 years. V O 2 max was estimated by the EB-test and measured during a maximal incremental exercise test during placebo and 10 mg Propranolol beta-blockade condition. The EB-test estimates V O 2 max based on the difference in heart rate, ΔHR, between two work rates (4 min cycling on each), a factor corresponding to the higher rate, heart rate at the lower rate, and age. Results: Maximal heart rate (mean ± SD; 165.5 ± 16.5 vs. 181.4 ± 9.8 bpm), ΔHR (36.4 ± 13.2 vs. 43.0 ± 11.4 bpm), and measured V O 2 max (48.2 ± 6.2 vs. 50.4 ± 7.0 ml/kg/min, 3.55 ± 0.74 vs. 3.67 ± 0.71 L/min) were significantly lower in the beta-blockade condition compared to placebo (P = < .001). This led to an overestimation of V O 2 max by the EB-test during beta-blockade, + 0.377 L/min (95% CI 0.281–0.473 L/min, + 11.2%), with no overestimation seen in the placebo condition, + 0.030 L/min (95% CI (− 0.112)–0.172 L/min + 0.8%). The coefficient of variance, indicating variance of estimated V O 2 max on an individual level, was lower during beta-block condition, 6.6%, compared to placebo, 9.9%. Conclusion: The EB-test systematically overestimated V O 2 max compared to measured V O 2 max during beta-blockade condition. Future research is needed to refine the test equation for usage in populations using beta-blockers.