Alcohol is part of the everyday fabric of modern social living. So meeting for a drink before or after a training session or race would seem quite natural.
Remember alcohol has short term effects on the brain—impaired reaction time, balance and hand-eye coordination. However most people would think that alcohol taken well before a race or afterwards would hardly be likely to affect your performance.
But does alcohol has subtle effects that could significantly affect your performance?
Alcohol and Performance
A study investigating the effects of alcohol consumption on running performance, five sprinters and five middle distance runners raced over 100, 200, 400, 800 and 1500 meters while sober and after taking 50mg -100mg of alcohol (the equivalent of 3-4 units) on an empty stomach. Running performances were negatively affected at all distances except for the 100 meters.
The more aerobic the exercise the greater the performance deficit
- In 800m a 55s = 42% performance reduction.
- In 1500m a 25s = 8% performance reduction.
The most likely explanation for the alcohol related drop in performance at 800m was decreased cardiac output due to vasodilation and the inhibition of the liver recycling pathway which converts lactic acid back into glucose. (McNaughton 1986 -1)
In another study researchers administered 25mL of ethanol (1 unit of spirit) to well-trained runners before and at 30 minutes of treadmill running (intensity of 80 – 85% VO2max).
They found that alcohol:
(I) adversely influenced running times in three out of four subjects forcing them to stop the session prematurely.
(2) depressed blood glucose after the second administration of the ethanol;
(3) increased the heart rate response to the exercise above that of the placebo grapefruit control.
The decrement in the running time was thought to be due to the apparent ethanol-induced hypoglycemia that occurred between 30 minutes and termination of exercise. Blood glucose was found to decrease by 24%. (Kendrick 1993 – 2)
A similar observed hypoglycemic effect during exercise has previously been reported with higher ethanol doses during both moderate and prolonged exhaustive exercise in a cold ambient environment.
Alcohol and Dehydration Effect:
Blood volume decreases, so less blood returns to your heart
Amount of blood your heart pumps with each beat decreases
Less oxygen-rich blood reaches your working muscles
Muscles have less oxygen to produce energy aerobically
Alcohol and Recovery
In the first hour after a race, you may feel like a beer, but what you really need is fluid and carbohydrates. A can of beer only contains about 14 grams of carbohydrate, so contrary to popular belief, beer is not a particularly good source of carbs.
Alcohol also slows recovery through its diuretic effect by delaying re-hydration. If you want to recover as quickly as possible from the race, you should not drink any alcohol.
Avoid mixing running with drinking alcohol
- Alcohol and its effects on sprint and middle distance running. L McNaughton BJSM 20:2 (June 1986)p 56-59
- Effect of ethanol on metabolic responses to treadmill running in well-trained men. ZV Kendrick, MB Affrime and DT Lowenthal. J Clin Pharmacol (1993) 33: 136
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