Pre-exercise Caffeine Supplementation Prevents Exercise-training Induced Attenuation Of Exercising Blood Pressure

BACKGROUND: The pressor response to submaximal exercise is prognostic of future cardiovascular risk and is attenuated by exercise training. Pre-exercise caffeine supplementation acutely increases the exercise pressor response, but it is unclear whether habitual pre-exercise supplementation interferes with the expected training-induced attenuation. PURPOSE: To determine the effect of habitual pre-exercise caffeine supplementation on training-induced adaptations to exercising systolic (SBP) and diastolic blood pressure (DBP) and heart rate (HR). METHODS: Thirty-six participants (mean ± 95% CI; 24 ± 2 y; 25 ± 3 kg/m2) were randomized to a caffeine (150 mg) supplement (CAF; n = 18) or placebo (PLA; n =1 8) group in a double blind, randomized, controlled trial. Participants completed high intensity exercise training on three non-consecutive days for six weeks and supplemented with CAF or PLA 30 minutes before exercise or upon waking on non-exercise days. Before (PRE) and after (POST) the 6-week intervention, SBP, DBP, and HR were measured at rest and during exercise at 50W and 75W on a cycle ergometer. Statistical analyses included three-way mixed factorial ANOVAs with lower order ANOVAs and post-hoc comparisons as necessary. RESULTS: A group × intensity × time interaction was observed for SBP (p = 0.006). SBP increased with increasing intensity from rest to 50 W and from 50W to 75W at both PRE and POST in the CAF and PLA groups (all ps ≤ 0.003). However, whereas exercising SBP decreased from PRE to POST at 50W (-11 ± 7 mmHg, p = 0.004) and 75W (-17 ± 7 mmHg, p < 0.001) in the PLA group, SBP did not change at any intensity from PRE to POST in CAF. An intensity × time interaction was observed for DBP (p = 0.007) indicating that resting DBP did not change (p = 0.98), but DBP decreased from PRE to POST at 50W (-8.5 ± 7 mmHg; p = 0.008) and 75W (-11.8 ± 7 mmHg; p < 0.001) independent of group. There were also main effects of intensity (p < 0.001) and time (p = 0.036) for HR, indicating that HR increased with increasing intensity, and that HR decreased PRE to POST training. CONCLUSIONS: Caffeine supplementation did not affect resting BP, but blunted training-related reductions in exercising SBP. Therefore, individuals may wish to avoid chronic pre-exercise caffeine supplementation if seeking to maximize the BP-lowering benefits of exercise. Funding was provided by Applied Food Sciences, Inc.