Habitual pre-exercise caffeine supplementation prevents exercise-training induced attenuation of exercising systolic blood pressure and double-product

We examined the effect of habitual pre-exercise caffeine supplementation on training-induced adaptations to exercising systolic (SBP), diastolic (DBP), pulse pressure (PP), heart rate (HR), and double product (DP). Young women (mean±SD; 24±7 y) were randomized to a caffeine (120 mg) supplement (CAF; n=17) or placebo (PLA; n=16) group, completed 6-weeks of high intensity exercise training on three non-consecutive days per week, and supplemented with CAF or PLA 30-60 minutes before exercise or else upon waking. Before (PRE) and after (POST) the intervention, SBP, DBP, and HR were measured, and PP and DP calculated, at rest and during fixed-power exercise at 50W and 75W. Statistical analyses included three-way mixed factorial ANOVAs with post-hoc comparisons as necessary. Group×intensity×time interactions were observed for SBP (p=0.0105) and DP (p=0.003). SBP and DP increased with increasing exercise intensity at PRE and POST in both groups. However, whereas SBP and DP decreased PRE to POST at 50W and 75W in PLA, SBP and DP did not change at any intensity from PRE to POST in CAF. As intensity×time interaction was observed for DBP (p=0.006) indicating no change in resting DBP, but reductions from PRE to POST at 50W and 75W independent of group. Main effects of intensity (p<0.0001) and time (p=0.03) were observed for HR, and a main effect of intensity was observed for PP (p<0.0001). Habitual caffeine supplementation blunted training-induced reductions in exercising SBP and DP. Individuals may wish to avoid pre-exercise supplementation if seeking to maximize BP-lowering benefits of exercise.