Effect of a moderate alcohol dose on physiological responses during rest and prolonged cycling.

Aim: We examined the acute effects of a moderate alcohol dose (48 g) ingested before prolonged cycling on acute physiological responses in eight healthy males (mean ± SD; 23 ± 2 years; 1.77 ± 0.04 m; 75.8 ± 4.1 kg).

Methods: In a randomized order, euhydrated participants completed two experimental sessions with the sequence of 150-min seated at rest, 90-min of cycling at 50% of the maximal rate of oxygen consumption ($\dot{\textrm V}\textrm O$2max), 120-min seated at rest. Participants drank 250 mL of flavored squash with or without alcohol (vodka; ~16 g) at 10, 40, and 70 min of the initial resting phase, giving a cumulative fluid intake of 750 mL with 48 g of alcohol. Heart rate, blood glucose, breath alcohol concentration, and respiratory gasses were recorded throughout the entire trial with cumulative urine volume recorded during both rest phases.

Results: Total carbohydrate (control = 115 ± 19 g: alcohol = 119 ± 21 g; P = 0.303) and lipid (control = 17 ± 4 g: alcohol = 20 ± 7 g; P = 0.169) oxidation was similar between conditions. Average heart rate was 7% higher in the alcohol condition (control = 111 ± 12 bpm; alcohol = 119 ± 11 bpm; P = 0.003). Blood glucose concentrations were similar between conditions during (P = 0.782) and after exercise (P = 0.247). Urine output was initially increased between conditions following alcohol ingestion before diminishing (P < 0.001) with no difference in total cumulative urine output (P = 0.331).

Conclusion: Consuming an alcoholic drink containing 48 g of alcohol in the hour before moderate intensity sub-maximal aerobic exercise led to detectable increases in heart rate and rate of urine production with no effect on substrate use.