Acute exercise reduces caffeine-induced anxiogenesis.

Abstract

This experiment examined the influence of acute exercise on anxiety following caffeine-induced elevations in self-rated anxiety. Eleven physically active, moderately fit males aged 25.1 +/- 3.8 yr completed four conditions in a within-subject, counterbalanced design involving 60 min of (1) cycling at 60% VO2peak or (2) quiet rest following placebo consumption (800 mg of lactose), as well as (3) cycling at 60% VO2peak and (4) quiet rest following 800 mg of caffeine. State anxiety and blood pressure were assessed 10 min before and 10 and 20 min after the conditions. A main effect for drug (caffeine vs placebo) determined by repeated measures ANOVA, (F(1,8) = 9.77; P = 0.01), indicated that state anxiety was elevated by caffeine. Drug effects were not obtained for blood pressure. Experimental hypotheses were tested by drug-by-condition (exercise vs quiet rest)-by-time (10 and 20 min postcondition) repeated measures ANOVA of change scores from the precondition baseline. A main effect for drug (F(1,8) = 5.81; P = 0.043) indicated that reductions in state anxiety were larger after caffeine ingestion. A condition-by-time effect (F(1,8) = 5.02; P = 0.055) indicated greater reductions in state anxiety 20 min after exercise compared with quiet rest. A condition effect for systolic blood pressure (F(1,10) = 4.56; P = 0.058) and condition-by-time interactions for diastolic (F(1,10) = 8.87; P = 0.014) and mean arterial blood pressures (F(1,10) = 8.46; P = 0.016) indicated reductions after exercise but not after quiet rest following both caffeine and placebo. We conclude that exercise can reduce anxiety elevated by a high dose of caffeine.