The effects of normoxic endurance exercise on erythropoietin (EPO) production and the impact of selective β1 and non-selective β1 + β2 adrenergic receptor blockade

Purpose: Habitual endurance exercise results in increased erythropoiesis, which is primarily controlled by erythropoietin (EPO), yet studies demonstrating upregulation of EPO via a single bout of endurance exercise have been equivocal. This study compares the acute EPO response to 30 minutes of high versus 90 minutes of moderate intensity endurance exercise and whether that response can be upregulated via selective adrenergic receptor blockade. Methods: Using a counterbalanced, cross-over design, fifteen individuals (age 28±8) completed two bouts of running (30-minute, high intensity vs 90-minute, moderate intensity) matched for overall training stress. A separate cohort of fourteen individuals (age 31±6) completed three bouts of 30-minute high intensity cycling after ingesting the beta antagonist bisoprolol, nadolol or placebo. Venous blood was collected before, during and after exercise and EPO response assessed. Results: No detectable EPO response was observed during or after high intensity running, however in the moderate intensity trial EPO was significantly elevated at both during-exercise timepoints (+6.8% ± 2.3% at 15 minutes and +8.7% ± 2.2% at 60 minutes). No significant change in EPO was observed post-cycling or between βAR drug trials. Conclusion: Neither training mode (running or cycling), nor beta-blockade significantly influenced the EPO response to 30 minutes of high-intensity exercise, however 90 minutes of moderate-intensity running elevated EPO during exercise, returning to baseline immediately post exercise. This exercise dependent and transient elevation may explain equivocal data regarding the effect of exercise on serum EPO and allow prescription of exercise to maximize EPO response for both performance and clinical applications.