Controlling for Acute Caffeine Intake in Cardiovascular Reactivity Research

Caffeine substantially affects cardiovascular functioning, yet wide variability exists in caffeine control procedures in cardiovascular reactivity (CVR) research. This study was conducted in order to identify a minimal abstention duration in habitual coffee consumers whereby CVR is unconfounded by caffeine; Six hours was hypothesized (average half-life). Thirty nine subjects (mean age: 20.9; 20 Women) completed a repeated measures study involving hand cold pressor (CP) and memory tasks. Caffeinated and decaffeinated coffee were administered. The following CV indices were acquired during baseline, task, and recovery epochs prior to coffee intake, 30 minutes-, and six hours post-intake: Heart rate (HR), high frequency heart rate variability (hfHRV), root mean squared successive differences (RMSSD), systolic and diastolic blood pressures (SBP, DBP), mean arterial pressure (MAP), pre-ejection period (PEP), left ventricular ejection time (LVET), and total peripheral resistance (TPR). Results support the adequacy of a six-hour abstention in controlling for caffeine-elicited CVR changes. The current study contributes to methodological endeavors in psychophysiology. Further investigations are crucial in establishing ideal caffeine controls, which would promote increasingly valid and reliable cross-study results.