Post-occlusive reactive hyperemia in habituated caffeine users: Effects of abstaining versus consuming typical doses.

BACKGROUND

Post-occlusive reactive hyperemia (PORH) typically requires caffeine abstinence. For habitual users, it is unknown if abstinence affects PORH.

OBJECTIVE

Compare PORH after habitual users consume or abstain from caffeine.

METHODS

On separate visits (within-subject), PORH was measured in 30 participants without abstinence from typical caffeine doses (CAFF) and with abstinence (ABS). Measurements included baseline and peak hyperemic velocity, tissue saturation index slopes during ischemia (Slope 1) and following cuff deflation (Slope 2), resting arterial occlusion pressure (AOP), heart rate (HR), systolic (SBP), and diastolic (DBP) blood pressure. All variables were compared using Bayesian paired t-tests. BF10 = likelihood of alternative vs null. Results are mean±SD.

RESULTS

Comparing baseline velocity (cm/s) between CAFF (9.3±4.8) and ABS (7.5±4.9) yielded anecdotal evidence (BF10 = 1.0). Peak hyperemic velocity (cm/s) was similar (CAFF = 77.3±16.7; ABS = 77.6±19.0, BF10 = 0.20). For slopes (TSI% /s), CAFF Slope 1 = -0.11±0.04 and Slope 2 = 1.9±0.46 were similar (both BF10≤0.20) to ABS Slope 1 = -0.12±0.03 and Slope 2 = 1.8±0.42. SBP and DBP (mmHg) were both similar (CAFF SBP = 116.0±9.8, DBP = 69.6±5.8; ABS SBP = 115.5±10.7, DBP = 69.5±5.4; both BF10≤0.22). Comparing AOP (mmHg) (CAFF = 146.6±15.0; ABS = 143.0±16.4) yielded anecdotal evidence (BF10 = 0.46). HR (bpm) was similar (CAFF = 66.5±12.3; ABS = 66.9±13.0; BF10 = 0.20).

CONCLUSIONS

In habitual users, consuming or abstaining from typical caffeine doses does not appear to affect post-occlusive reactive hyperemia.