How Does Alcohol Affect Your Performance? (#55)

Here comes the much-anticipated part two of our alcohol series. In the first article, we discussed the impact of alcohol on your recovery. You found out how your glycogen replenishment and muscle protein rebuilding are affected by different doses of alcohol after training and competition.

To stay on track, we now focus on similar parameters, but this time examining how alcohol affects your acute performance if consumed before a competition. Practically, this means you'll soon understand how those Friday/Saturday drinks affect your performance in a Sunday morning competition — if you still have alcohol in your blood. The conclusion is clear: the closer the alcohol consumption is to the competition, the higher the risk of impaired performance.

One of the main negative effects is the impact on heart muscle. Previous studies have shown that the heart's stroke volume decreases when alcohol is present in the blood. If the heart pumps less blood per beat, it has to beat more frequently per minute to deliver oxygen to the muscles, which negatively affects performance.

Additionally, our entire substrate metabolism is negatively affected. The muscles' ability to burn glucose/glycogen decreases. The liver's ability to manage lactate and to produce new glucose through gluconeogenesis is inhibited, blood sugar drops, and perceived exertion increases. A rule of thumb is that as long as alcohol is in the blood, the metabolism for other energy sources is downregulated.

In experiments on rodents, negative effects on the formation of capillaries and mitochondria have also been observed. This applies to daily intake over a period of 12 weeks and is therefore not something that happens after 1-2 beers. The effect is likely present from the start, but it takes some time before it becomes truly inhibiting. The recommendation is therefore not to drink every day for three months.

Your muscles function thanks to calcium, which essentially initiates the muscle work itself. In an interesting study on rodents, a reversible (which is a relief) inhibition of calcium transport in the muscle was observed. Negative effects were seen even at levels around 20 mM alcohol, which the authors interpret as equivalent to approximately 1 drink, and the effect increased with higher alcohol intake. At 100 mM ethanol in the blood (what is often called binge drinking), the effects were significantly negative. That dose is reached at about 4 units of alcohol over 2 hours for women and 5 units for men. One unit is, for example, 1 beer or a glass of wine.

First up is a study involving 13 cyclists (VO2max 61 ml/kg/min, average weight 70 kg). The participants served as their own control group and consumed either a drink with 20 g of carbohydrates (grapefruit juice) and 3 cl of spirits (Smirnoff Vodka) or just the grapefruit juice 15 minutes before starting the cycling. An interesting detail — and standard practice in similar studies — is that participants drink with a nose clip and are asked to rinse their mouths with water immediately afterward to minimize the risk of knowing whether they received alcohol or a placebo. So if you thought it was a cozy lounge and a well-composed drink — forget it.

They drank the beverage, warmed up for 15 minutes, and then did a classic 60-minute time trial where the goal is maximum average power. The result: their performance dropped throughout the test by approximately 10 W, or about 4.1 percent. They also rated perceived exertion as equally hard, or even a little harder, despite the watts being lower during the test.

Conclusion: As little as 3 cl of vodka can slow down your performance if consumed close to the start of a competition.

*Black bars represent participants with alcohol in their blood, while white bars depict the occasion with placebo.

A review from the year 2000 summarized that performance was reduced by 11.4 percent when alcohol was consumed 24 hours before performing. Quoted from the study:

Consumption of alcohol 24 hours prior to exercise has also been shown to reduce aerobic performance by 11%.

This figure averages across various sports and distances, but the trend is clear: less alcohol equals less performance reduction; more alcohol equals greater performance reduction. It's perhaps unsurprising, particularly when the authors of the review note that much of the effect can be attributed to that non-energized feeling the next day — more commonly known as a hangover.

“This may be due in part to the hangover effect of alcohol consumption”.

The negative impacts of alcohol are especially evident in longer performances. However, there are some studies where no performance reduction from alcohol intake prior to performance has been observed. This could be due to study design or the type of performance — shorter and more explosive sports seem to be less affected than longer running and cycling sessions.

Similar observations have been noted for runners as for cyclists. In a study, participants were given 2.5 cl of spirits 10 minutes before and 30 minutes into a 60-minute treadmill test at 80-85 percent of VO2max. From 30 minutes into the test onward, participants experienced a significant drop in blood sugar (hypoglycemia), and both heart rate and oxygen cost were higher for those who drank compared to placebo. Even though it was a small group, the drop in blood sugar was as much as 24 percent — clearly indicating that you don't want alcohol in your bloodstream when you're aiming to perform.

In a study from 1986, researchers tested 5 middle-distance runners and 5 sprinters. The research was quite new in the field, and interestingly, they set out to explore whether alcohol might potentially enhance performance — a hypothesis that existed at the time. However, they found back then that alcohol intake was purely negative, most detrimental for middle-distance runners (800 m and 1500 m) but less negative (still negative) for sprint distances of 200 m and 400 m. The only ones not affected were the 100 m runners.

Their conclusion is worth a slight chuckle, but based on the knowledge available at the time, the research was necessary to show that a couple of vodka shots won't make you faster:

”Alcohol is not an ergogenic aid in that it does not improve performance. Clearly, in all but the 100 m sprint, differing levels of alcohol had varying, but consistently detrimental, effects on timed performance. In the 100 m, there was no such detrimental effect on timed performance, but neither was there any positive effect on running performance. We would therefore not recommend the use of alcohol in sprinting performance. Further research is required into the effects of alcohol during anaerobic exercise to determine its effects.”

One of the main reasons for reduced performance with acute alcohol intake is the increased risk of injury. Statistically, athletes who consume alcohol at least once a week are more than twice as likely to get injured, regardless of the sport. We all know that an injury significantly hampers performance by limiting training volume and reducing the quality of training when you're finally back on track.

Alcohol in connection with training increases the risk of injury. In some sports, alcohol is also prohibited during competition.

Alcohol doesn't just lower your performance. In fact, there are four sports where alcohol is classified as a doping substance and included on WADA's list. The doping classification only applies during competition, and the threshold is 0.1 per mille. So you won't get caught if you are doping tested at home while training archery.

• Air sports (for example, speed diving, aerobatics, parachuting)
• Archery
• Motor sports (all motor sports)
• Boat sports (applies to powerboating)

Previously, motorcycle racing and karate were also on the list, but not at the time of this article (2016).

American College of Sports Medicine (ACSM) offers clear guidelines: avoid alcohol consumption during the 48 hours leading up to a performance and avoid alcohol during the performance itself if your goal is to achieve peak performance. The data in this article indicate performance drops of 4–11 percent in various sports and distances with alcohol intake from 24 hours before up to a few minutes before and during the event.

The negative effect grows with increasing blood alcohol content. Adverse acute effects have been documented from as little as 0.1 blood alcohol concentration (as per the 1986 study on runners), which could be reached by consuming, for instance, a glass of wine or a beer shortly before the event.

If you abstain from alcohol for 48 hours before performance, there should be no impact from prior consumption, even if you've had quite a bit earlier. However, we wouldn't risk "going all out" with your last beer 49 hours before the start — better to err on the side of caution and plan so that you can enjoy the social aspect and still perform when it counts.