Post exercise rehydration: effect of beer consumption on fluid balance

Adequate rehydration after endurance exercise is important. Among amateur
team-based sports, it is common to drink moderate to large amounts of alcoholic
beverages, mainly beer, after training or competition. Alcohol is known to
increase urine output, which could interfere with adequate rehydration after
exercise. It is suggested the diuretic effect of alcohol is blurred when the
body is dehydrated. Moreover, rehydration drinks typically consist of water,
carbohydrates and electrolytes, i.e. sodium. Beer contains - besides alcohol -
water, carbohydrates and a small amount of electrolytes. The final consequences
for rehydration and fluid balance after exercise for beer with different
alcohol contents are not completely clear. Therefore, the objective of this
proposal is to assess the effect of beer consumption, with a range of alcohol
content, on fluid balance after exercise-induced dehydration. The rehydration
capacity of these beverages is compared with a rehydration drink.

Objective: To assess the effect of beer consumption, with a range of alcohol
content, on fluid balance after exercise-induced dehydration.

Hypothesis: Based on the glucose and electrolyte composition of beer, and the
blurred effect of alcohol in the dehydrated state, it is expected that
non-alcoholic and low-alcohol beer result in a comparable fluid balance as a
hypotonic glucose-electrolyte rehydration drink, while lager beer (5% alcohol)
is associated with an increased urine production and a retarded rehydration,
like water.

Cross-over intervention trial.

Participants will receive five test-drinks in a random order: beer (lager),
low-alcohol beer, non-alcoholic beer, water and rehydration drink. At least 7
days will be considered between test days.

There are minor risks for the participants during this study. Subjects are only
mildly dehydrated and receive drinks, equal to their fluid loss directly after
exercise. A maximum amount of three alcoholic beverages will be provided during
each condition. Participants are not allowed to leave the research facilities
until the breath alcohol test is within the accepted range (i,e 0,22 mg/L
expired air, ~0,5 °/°°). The exercise test will result in fatigue, and can give
rise to some muscle soreness afterwards. All functional measurements (urine
volume, urine osmolality, body weight, body composition (BIA/BIS) and breath
alcohol concentration) are non-invasive and risks are therefore minimal.
Subjects have to adhere to specific guidelines one day before every test
(standardized diet, no physical activity, overnight fast, no alcohol
consumption, drinking at least 2 liters of fluid) and have to fill out a
questionnaire for screening purposes. There is no direct (health-related)
benefit for the participant. The time investment requested from the
participants excluding travel time is in total 37 hours for 6 visits and
screening.
Participants that complete the study will receive ¤ 180.