Many people advise against the consumption of alcohol and caffeine containing beverages when fluid replacement is desired because they have been shown, at least in some circumstances, to act as diuretics. However, it is obvious that many people enjoy consuming these types of beverages in many circumstances.
We therefore undertook a study to investigate the effect of consuming alcohol after exercise in the heat sufficient to induce dehydration equivalent to 2.01 (0.06)% of body mass. Over a 60 minute period beginning 30 minutes after the end of exercise, subjects consumed a volume equivalent to 150% of their mass loss of drinks containing 0, l, 2 or 4% alcohol; the drink composition was identical in all other respects.
The volume of urine produced and excreted for the 6 hours after drink ingestion was measured and was found to be related to the quantity of alcohol consumed, with a larger volume the more alcohol that was consumed (table 14.3). However, despite the definite tendency for the urinary output to increase with increasing alcohol, only with the 4% beverage did the increased value approach significance.
The calculated decrease in plasma volume with dehydration was about 7.6% across all trials. With rehydration the plasma volume increased, but the rate of increase seemed to be related to the quantity of alcohol consumed; at the end of the study period, the mean (SD) increase in plasma
Volume of drink consumed and fraction of fluid retained 6 hours after ingestion of drink of various alcoholic strengths (0, 1, 2, or 4%). Values are mean (SD)
| Measure | 0% | 1% | 2% | 4% | ||||
| Fraction of fluid retained (%) | 2178 59.3 | (191) (15.7) | 2240 53.1 | (147) (11.0) | 2275 50.0 | (154) (16.2) | 2155 40.7 | (125) (13.7) |
volume relative to the dehydrated value was 8.l (3.2)% with 0% alcohol, 7.4 (2.7)% with l%, 6.0 (3.4)% with 2%, and 5.3 (3.4)% with 4%.