Authors’ reply to ‘Reference values for systolic blood pressure at upright bicycle exercise tests’ by Alfred Hager

We are pleased by the attention and acknowledgement given by Professor Hager ¹ to our article regarding reference values for systolic blood pressure (SBP) during bicycle exercise testing, recently published in the European Journal of Preventive Cardiology. ² Although none of the authors of our article is a native German speaker, we appreciate the reference provided by Professor Hager to the article published in a German sports medicine journal in 1984, by Heck et al. ³ With a slight risk of misinterpreting the data presented in German by Heck et al., ³ we feel reassured in our findings that: (a) SBP increases linearly with increasing workload in both men and women; and (b) the linear increase is similar across ages, although slightly steeper in older individuals in addition to starting from a higher baseline level (i.e. SBP at rest) at older age.

Professor Hager suggests a rule of thumb in individuals less than 40 years of age, that the predicted SBP_max should be approximately 0.33 mmHg/Watt plus the SBP measured at rest, before exercise. ¹ We agree that this seems like a feasible and reasonable approach, and could be adopted clinically as long as the measurement of SBP at rest is well standardised, the SBP_max measurement is obtained at or very close to the maximal workload, and different reference values are used for individuals aged over 40 years. However, the most important question is probably not the predicted SBP_max per se, but rather when the measured SBP_max or the SBP/Watt slope exceeds the predicted value to an extent that is clinically relevant. For this purpose, we suggest to either use the sex and age-specific upper 90th or 95th percentiles provided in the appendices of our article, or the multivariable regression equations in Table 2. ² As Professor Hager points out, the latter is probably preferable for research purposes and requires implementation in exercise testing software or the use of our supplementary Excel sheet to be feasible in clinical practice.

Future research is warranted to evaluate these reference values from a prognostic point of view, as previously done for the SBP/metabolic equivalent (MET) slope in treadmill testing. ⁴