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Nutrition and Performance in Sport

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Christophe Hausswirth

Chapter 3. Nutrition and lifestyle

Topic 13. The effects of alcohol

Yann Le Meur, Amélie Fosse, Christophe Hausswirth, Axel Heulin, Véronique Rousseau, Eve Tiollier et École Lenôtre

Texte intégral

Questions and answers

Key points
Although little is known about how athletes consume alcohol, in some sports and during post-competition recovery periods, consumption can be excessive. There is no reason to completely forbid the consumption of alcohol by athletes, but we must emphasize that:
– alcohol affects sleep quality by limiting deep sleep phases;
– alcohol slows muscle glycogen resynthesis;
– alcohol perturbs post-exercise muscle and bone regeneration mechanisms;
– alcohol dehydrates;
– beer does not accelerate the recovery process.

Why is regular consumption of alcohol more problematic for athletes than for non-athletes?

1In high-level athletes, physical capacities are developed through biological mechanisms triggered in response to stimuli created by daily training. These adaptation mechanisms (muscle tissue synthesis, increased activity of metabolic enzymes, etc.) are part of a broad frame of coordinated reactions triggered during training, but which continue beyond this, during recovery periods following training sessions and competitions. Harnessing these periods, to maximize their effect, also plays a major role in how performance levels progress, since it directly determines how exercise-induced physiological reactions are implemented. In other words, the overcompensation phenomena expected by the coach and the athlete can depend on efficient recovery strategies that must be scheduled and implemented between exercise sessions. Currently, few studies have investigated the effects of alcohol consumption in athletes. However, some results clearly indicate that it can interfere with various adaptive mechanisms stimulated by exercise, and thus could really hinder the athlete’s progression both short term and long term. Indeed, consuming alcohol post-exercise triggers a certain number of disruptions of physiological processes, among which:

  • Alcohol can favour dehydration. Today, it is well known that alcohol is a diuretic. This is due to its inhibition of the liberation of vasopressin, a hormone synthesized by the hypothalamus which slows urine production. Of course, the amplitude of this effect depends on how much alcohol is contained in the drink. The stronger the drink, the greater the diuretic effect, and the more chance dehydration will ensue. Thus, drinking one 25-ml glass of 40% proof alcohol (which is equivalent to 15 ml of water with 10 ml of pure ethanol) generates the production of 100 ml urine, which represents a net deficit of 85 ml. It has been shown that post-exercise dehydration is aggravated by drinks from a threshold alcohol concentration of about 4%. If alcohol is diluted (i.e. drinks containing less than 4% alcohol), the effect on diuresis is negligible.

  • Alcohol affects muscle regeneration mechanisms. Several scientific studies have shown that consuming alcohol after a physical effort slows the repair of exercise-induced muscle microlesions. In particular, they showed that a moderate consumption of alcohol after a training session significantly decreased the recovery of strength qualities. This phenomenon is directly linked to disruption of cellular muscle regeneration mechanisms, and not to a systemic effect. Therefore, it is preferable to avoid regular consumption of alcohol after bodybuilding sessions, particularly when participating in sports causing extensive muscle damage. Otherwise, the risk of muscle injuries increases significantly. This recommendation is also crucial in the context of a programme aiming to increase muscle mass.

  • Alcohol has a deleterious effect on osteogenesis. Just as it affects the mechanisms controlling muscle tissue synthesis, the consumption of alcohol perturbs bone synthesis. This is particularly worrying in sports imposing significant constraints on the skeleton, or in those associated with problems with bone health (e.g. in weight-bearing sports or in aesthetic sports). Although it has yet to be scientifically confirmed, it seems possible that regular consumption of alcohol limits bone density and increases the risk of stress fractures in athletes.

  • Alcohol slows glycogen resynthesis. It is now well known that consuming alcohol has various consequences on carbohydrate metabolism, both at the hepatic and muscle levels. Several studies have shown, in particular, how a small amount of alcohol ingested after a training session can significantly slow glycogen synthesis in the liver and muscle fibres. Thus, the consumption of alcohol should be limited to the absolute minimum when training is associated with a particularly high energy expenditure. Respecting this recommendation during an intense training period preserves the athlete’s capacity to sustain their training load and reduces the risk of overload.

Does drinking beer after physical exercise favour recovery?

2It is often said that drinking beer can enhance the quality of recovery after a tiring exercise. Indeed, beer contains a lot of polyphenols, which contribute to the body’s antioxidant stores. However, it should be remembered that the only results supporting this hypothesis were obtained with alcohol-free beer! This American study showed that drinking 1 litre of alcohol-free beer per day during the five weeks surrounding a marathon decreased the risk of upper respiratory tract infections in trained athletes threefold. Although coherent hypotheses have been advanced to explain this positive effect, this result needs to be confirmed in other studies. Currently, there is no scientific reason to assert that drinking beer (containing alcohol) during the recovery phase presents a real physiological advantage for athletes. On the contrary, beer has an alcohol concentration above the threshold stimulating diuresis (4%), thus consuming it post-exercise perturbs rehydration mechanisms and increases electrolyte losses caused by the physical effort.

Does drinking alcohol promote better sleep?

3Drinking alcohol before going to bed modifies sleep quality in two contradictory ways. On the one hand, consuming alcohol 30 to 60 minutes before going to bed reduces the time it takes to fall asleep, which explains why people think that alcohol enhances sleep quality. However, beyond this initial positive effect, alcohol significantly perturbs sleep by reducing the duration of deep sleep phases, during which true recovery takes place. This disruptive effect lasts as long as alcohol has not been completely metabolized by the body, and since the alcohol level only drops by about 0.1 g.h−1, it is easy to see how sleep quality could be affected during the night following an evening of over indulgence. In addition, several studies have shown that drinking alcohol raises the heart rate and the respiratory rate, while also causing intestinal disorders and headaches, all of which are likely to affect sleep quality. Given the major role played by sleep quality on the recovery processes in athletes, this population should avoid consuming alcohol, particularly during intense training periods.

Why does consuming alcohol favour weight gain?

4Alcohol in itself is a considerable source of energy, since ethanol has an energy density of 7.1 cal.g−1 (against only 4 cal.g−1 for carbohydrates and proteins). Therefore, consuming alcohol is likely to increase an athlete’s energy intake. Alcohol also has indirect effects on metabolism: it reduces lipid oxidation, favours adipocyte expansion and increases blood triglyceride levels. In other words, drinking alcohol favours a positive lipid balance and, as a consequence, an increase in fat mass in the medium term, especially in the abdominal region. In addition, alcohol is often consumed in combination with fatty and sweet foods, increasing its deleterious effects on body composition and weight. Thus, for those who wish to maintain a constant body mass, it is important to limit the consumption of alcohol.

In the long term, what are the risks of excessive alcohol consumption?

5Although the consumption of alcohol is often associated with relaxation and happiness, we must keep in mind that an excessive consumption of alcohol has significant health consequences. Indeed, currently, many epidemiological studies show that consuming alcohol significantly increases the prevalence of various diseases (cancers, osteoporosis, hepatic diseases, and mental diseases, among others). Most studies, including very recent meta-analyses, show a linear relationship between these risks and alcohol consumption. This is even observed when consumption does not exceed one or two glasses per day. Based on this data, scientific experts logically agree that alcohol consumption should be limited to the equivalent of one glass of wine per day. This amount should only be exceeded occasionally, and then only moderately exceeded.

Why is it especially important to supervise how young people consume alcohol?

6Epidemiological studies investigating early consumption of alcohol reveal that the older a person is when they start consuming alcohol, the better. It is also better when initiation occurs in an appropriate environment. On the contrary, the earlier teenagers start drinking without supervision, the more often they drink to excess. This is particularly worrying because an excessive consumption of alcohol presents more serious risks in teenagers than in adults, mainly because the teenage brain is still developing and will undergo various transformations during puberty. Thus, for an equivalent amount of alcohol absorbed, a teenage brain is more likely to be damaged than an adult brain. As adolescence is associated with extensive hormonal modifications, consuming alcohol during this period could perturb the hormonal balance required for the development of organs, muscles, bones and the reproductive system. Finally, according to some studies, young people who start regularly consuming alcohol before the age of 21 have 70% more risk of developing drug problems in later life. For all these reasons, young people who plan to perform at a high level should, as far as possible, be informed of the risks, and their habits with regard to the consumption of alcohol should be closely monitored.

Practical applications

1. General notions

Equivalents to a standard alcoholic drink

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Learn how to estimate your alcohol consumption

7 Volume of alcohol consumed (in litres) × 8 (alcohol density) × alcohol proof. Example:

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Daily consumption limits

8 To prevent the appearance of alcohol dependence, avoid regularly consuming alcohol

Image 10000000000000230000001F5B2871AD.jpgFor athletes, even moderate alcohol consumption is not recommended

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2. Excessive alcohol consumption promotes weight gain

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3. Beware of clichés!

9 "A beer quenches thirst"

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10On the contrary, alcohol dehydrates by stimulating urine production

11 "A beer helps with recovery"

Image 10000000000000E3000000743AD9B002.jpg

12Alcohol prevents the body from recovering by perturbing the processes of muscle regeneration and carbohydrate replenishment

13 "Alcohol warms you up"

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14On the contrary, alcohol favours redistribution of the blood towards the skin and thus results in a drop in body temperature

15 "Alcohol gives you strength"

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16On the contrary, exercise-related exhaustion appears more rapidly after consuming alcohol

17 "Alcohol helps you sleep"

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18Although alcohol helps you to fall asleep, it perturbs sleep quality during the second half of the night

4. Specific recommendations for athletes

It is not recommended to consume alcohol every day (even in moderation)

Particularly avoid alcohol in the hours around training sessions

Alcohol prevents the body from adapting to the demands of training

Alcohol...
■ Recurrent injuries
■ Lifestyle
■ High-level competition
■ Stressful environment (sport, home life)

5. Recommendations for "high-risk" nights

19 The effects of over-indulging in alcohol can have consequences on training up to two to three days later

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20 Decide on a number of glasses that you will not exceed (moderate amount) and try your best to stick to it, however persuasive your friends are

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What should you drink?

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How should you drink?

21 Drink slowly (put your glass down between each sip)

22 To properly monitor your alcohol consumption, finish your glass before filling it up again

23 Do not have more than one standard drink per hour

24 Eat before going out and during the night

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25 Do something else while drinking (play video games, cards, darts, etc.)

26 Avoid drinking games: they encourage you to drink faster than you normally would

27 Don't drink anything you are not sure of and watch your glass

Image 100000000000002D0000001FC11E49F6.jpgIf you are driving for a group you should not drink any alcohol

Recipe

Saudi champagne

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Photo credit: Thibaut Ruggeri.

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28For 1 litre

29Preparation time: 20 minutes

Difficulty: Image 10000000000000290000002363709215.jpg

30Ingredients

31 2/3 litre apple juice

32 1/3 litre sparkling water, such as “Perrier”

33 1 lime

34 1 Granny Smith apple

35 12 fresh mint leaves

36Slice the lemon and dice the apple finely.

37Add the sparkling water, the apple juice and the mint leaves.

38Leave the flavour to develop for several hours in the fridge before drinking.

39Serve chilled.

40Chef’s note

41This refreshing cocktail is a good alternative to alcoholic drinks during a party. It ensures hydration. It only provides carbohydrates and can thus also be had as a recovery drink after intense exercise. When used in this context, it is best to use a sparkling water that is rich in bicarbonates.

42Nutritional analysis per person

Energy (Cal)

Carbs (g)

64

16

Lipids (g)

Protein (g)

0

0

Auteurs

© INSEP-Éditions, 2015

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