Is drinking during lockdown harming my exercise performance?

Tuesday, May 12, 2020. Author FitnessGenes

Is drinking during lockdown harming my exercise performance?

Go for a walk in your local area and it may seem that more people than ever are exercising outdoors.

Government sources suggest there has been a 70% rise in the number of people cycling in some parts of the United Kingdom. Hop over the pond to the US, and running is apparently enjoying a boom because of social distancing measures due to COVID-19.  

Although we may be running and cycling more than previously, figures also suggest that many of us are drinking more too. During March 2020, sales of alcoholic beverages increased by 22% in the UK and by 55% in the US compared to the same period last year

According to a recent survey by Alcohol Change UK, 8.6 million adults in the UK have been drinking more frequently since lockdown measures were imposed. (In better news for public health, however, the survey also found that 14 million people are actually drinking less often or have stopped drinking alcohol entirely.)

These trends in exercise and drinking behaviour raise an interesting question – by drinking greater amounts of alcohol, are we undoing all the hard work we’ve put into exercising more?

This article looks at some of the research into this question. Before we continue, it’s worth quickly noting that many of the studies cited have been conducted predominantly on small numbers of elite or otherwise well-trained, male athletes. Consequently, their findings may not be generalisable to the wider population.

Drinking alcohol before exercising

Most of us tend to drink after, rather than before, we exercise. Reflecting this pattern of consumption, not many studies have assessed the effects of consuming alcohol shortly before exercise performance.

Of the few studies that do exist, findings are mixed. For example, one study found that ingesting 0.44 and 0.88 ml / kg bodyweight of 95% alcohol half an hour before a progressive cycling test had no effect on exercise performance.

By contrast, a small study of sprinters and middle distance runners found that alcohol consumption worsened performance at 200m, 400m, 800m and 1500m distances, but not 100m distances.

In terms of strength performance, a blood alcohol concentration of 140 mg / dL was found to have no effect on isokinetic and isometric knee extension.  

In all likelihood, the effects of alcohol on exercise performance will largely depend on how much you drink. We know that alcohol is a central nervous system depressant and impairs balance, co-ordination, and reaction time in a dose-dependent fashion. Therefore, higher alcohol doses are more likely to impair exercise performance.

On this note, some studies have suggested that exercise performance gets significantly affected at blood alcohol concentrations around 92 mg / dL (20 mmol/L). To put that figure in perspective, in the USA, legal intoxication is defined as a blood alcohol concentration of 80 mg / dL (17.4 mmol/L) or 100 mg / dL (21.7 mmol/L) or above.

In other words, then: if you’re drunk, your ability to exercise suffers. Quelle surprise!

Rehydration following exercise

It’s well established that alcohol is a diuretic – it increases the amount of water lost from our body as urine. More specifically, drinks containing 4% w/v or more alcohol inhibit the release of a hormone called ADH (antidiuretic hormone or vasopressin).

ADH, as its name suggests, normally acts to prevent diuresis and stimulate the reabsorption of water back into the bloodstream, so less is lost through urine. By inhibiting the release of ADH, alcohol increases water loss, which can potentially worsen dehydration and hamper efforts at fluid replacement after exercise. Being inadequately hydrated can then lead to poorer exercise performance later on (e.g. the following day).

So, in order to avoid dehydration, should you refrain from drinking alcohol after exercise?

Again, it depends on how much you drink. Studies suggest that an alcohol dose of less than 0.49 g / kg bodyweight is unlikely to have much negative effect on rehydration. This figure equates to about 3 – 4 standard alcoholic drinks for a 70 kg person (WHO criteria classify a standard drink as containing 8 g of alcohol).

Replenishing glycogen stores

Glycogen is one of the body’s major fuel stores. When we exercise, glycogen stores in the liver and skeletal muscle are broken down to release glucose, which, in turn, can be used to fuel muscle contraction.

During recovery after exercise, we replenish these glycogen stores. This is one reason why consuming carbohydrates is important after endurance exercise – we break down the carbohydrates into glucose, which is then built back up into glycogen stores.

Alcohol may interfere with this process of glycogen replenishment and has been shown to reduce glucose uptake into muscles. Nevertheless, this may be offset by consuming alcohol alongside a carbohydrate meal.

In this respect, a study of cyclists found that glycogen storage was not affected by drinking 1.5 g/kg bodyweight of alcohol along with a high-carbohydrate meal. When some of the carbohydrate was replaced with alcohol, however, so that a greater proportion of total caloric intake came from alcohol, glycogen storage was reduced.

Therefore, from the perspective of replenishing glycogen post-exercise, it’s important not to drink alcohol as a substitute for proper post-workout nutrition (particularly carbohydrates).

Exercise-induced muscle damage

Intense exercise, particularly eccentric exercise, actually initially damages our muscle fibers. During recovery after exercise, our muscles begin to repair and develop adaptations that improve exercise performance with continued training.

Eccentric exercise involves the contraction of muscles as they lengthen. For example, during the lowering phase of a bicep curl, the biceps muscle is lengthening as it contracts and generating tension to resist the weight of the dumbbell acting downwards. After heavy eccentric exercise, the strength of muscle decreases until it is fully repaired.

Studies have found that alcohol can worsen strength losses following eccentric exercise. For example, one study asked subjects to complete 300 eccentric contractions of the quadriceps muscle of one leg. Subjects then either consumed 1g/kg bodyweight of alcohol or the same amount (in calories) of orange juice. Compared to those who drank orange juice, subjects who consumed alcohol experienced a significantly greater loss of muscle strength at 30 and 60 hours after the exercise bout.

As with other performance outcomes, the effect of alcohol on exercise-induced muscle damage depends heavily on dose. Other studies have found that drinking 0.5 g / kg bodyweight in alcohol does not worsen losses in strength following eccentric exercise.

Muscle protein synthesis

In order for muscles to grow in size and strength, muscle cells need to build new proteins (such as contractile proteins) at a greater rate at which they break them down.

The process of building amino acids into proteins is known as muscle protein synthesis (MPS). You can read more about this in your Muscle hypertrophy (mTOR) trait.  

In vitro studies strongly suggest that alcohol consumption impairs muscle protein synthesis, although how this applies to humans in vivo is less well-established.

In one study, muscle protein synthesis was reduced by 24-37% in subjects consuming alcohol after exercise. This effect was present even when alcohol was consumed in conjunction with protein and carbohydrate.

The subjects in this study consumed about 1.5 g / kg bodyweight of alcohol, which equates to between 10 – 13 standard drinks (WHO classify a standard drink as containing 8g of alcohol).

If you’re keen to maximise muscle gains then, heavy drinking after strenuous exercise is not recommended.

 

Recovery from injury

If you’ve ever been injured, a question you’ll likely ask is, “How quickly can I return to exercise?”

One answer to this question may be, “Less quickly if you drink large amounts of alcohol.”

Recovery from injury involves various inflammatory and hormonal processes that act to remodel tissue and promote healing. Such processes can be negatively impacted by high intakes of alcohol.

For example, alcohol is known to inhibit the production of pro-inflammatory cytokines, thereby dampening the acute inflammatory response to tissue injury. This delays recovery as acute, controlled inflammation is a central part of tissue repair.

Furthermore, alcohol causes vasodilation – widening of blood vessels. It has been shown that alcohol-induced vasodilatation increases blood flow to sites of tissue injury, thereby worsening swelling and delaying healing.

High intakes of alcohol (1.5 g/ kg bodyweight) also inhibit the production of testosterone and growth hormone. Both of these hormones are involved in muscle regeneration and protein synthesis following tissue injury.

Finally, alcohol is well known to affect sleep quality, another key component of exercise recovery.

Although more research is needed, given the above findings, it's recommended that you moderate your alcohol intake if you wish to expedite recovery from injury. 

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