Following a time trial win on the penultimate day of his seventh Tour de France triumph, Lance Armstrong was asked how victory tasted. “Like a cold beer in 20 minutes,” he replied. Given that he had a four-minute buffer on his nearest rival, Armstrong probably thought he could afford a little alcoholic refreshment. And for the rest of us mere mortals, the idea of a beer or two after racing or training can be pretty attractive too.
The question is: does it do more harm than good? Reports of carbohydrate replenishment and mysterious vitamin benefits tend to get bandied about with relish in the pub following training, but can we really trust them? To clear up the confusion, we look at exactly what a post-race pint will do for you – and what it won't.
As alcohol is a diuretic, and makes you go to the toilet a lot, most people believe beer is a dehydrating agent and therefore will be totally useless in terms of post-exercise rehydration. In fact, there have been several scientific studies showing that the situation is slightly more complex than that – most beers are more than 90% water after all.
A study at Loughborough University tested various strengths of alcohol ingestion against water and came up with some fairly clear cut results. They found that the diuretic effect of alcohol ingestion became significant at concentrations of around 4%. At the 2% level, alcoholic drinks performed about the same as water and if consumed together with electrolytes in the form of supplements or solid food, they will be even more effective. However, once you go over the 4% threshold, things start to decline rapidly. The study showed that athletes who drank stronger drinks eliminated about 16 ounces more urine over the course of four hours than those who drank lower alcohol (2%) drinks.
So, a few low-alcohol beers or shandies is probably okay, but if you're drinking anything that's 4% or stronger, you're probably making things worse rather than better.
Vitamins and minerals
Despite what you may have heard, beer doesn't do very well in this regard. Though it does contain significant amounts of B vitamins and trace amounts of calcium, phosphate, magnesium and potassium, it's useless in terms of vitamin C and most experts believe it's not a great source of replenishment for the essential vitamins and minerals lost through exercise. You're better off saving the beer until after you've had a healthy snack such as cereal with milk and a banana that will provide the potassium and sodium required for ideal rehydration, along with some vital carbs and proteins. But it's not quite all doom and gloom, especially with regards to protein. A recent study in Holland discovered that beer can boost concentrations of vitamin B6 in the blood and this helps to process protein and relieve those aching muscles.
Carbohydrates and protein
Again there's good news and bad news here. Beer typically has a reasonably high calorie content which may make it seem attractive to a cyclist looking to replace glycogen stores. But the trouble is that the majority of the calories come from the alcohol, which is not a carbohydrate and therefore will tend to get stored as fat rather than replenish your energy stores. Plus, your body processes the alcohol first, ahead of fat, protein or carbs and thus drinking slows down the burning of fat caused by exercise. However, that doesn't mean beer will not replenish energy levels at all. Most beers still contain about 4g of carbohydrate per 100ml serving, which, considering your average sports drink only contains a couple of grams more, isn't a bad level. In terms of protein however, the story is almost all bad. Beer simply doesn't contain very much protein and is thus unlikely to help in rebuilding damaged muscles.
So, if you're going to have a few pints after the race, make sure you eat something as well, otherwise your recovery will be hit hard.
In terms of rehydration beer does okay provided you stay below the 4% threshold (either by choosing a low-alcohol beer or making a shandy out of it) and there is some evidence that it may also help with protein processing and hence muscle damage. But the alcohol calories in beer make it generally poor for replacing glycogen and protein and hence re-fuelling for another session. So if you know you're heading to the pub after the race, pack a suitable snack and stick to the lower-strength stuff and your recovery shouldn't be affected too much.
One final word of warning though, try to stick to just a couple of pints – a team from Auckland conducted possibly the most unnecessary experiment ever when they proved that having a hangover affects next-day exercise performance. But for the record, it apparently makes you 11.4% worse.