A common belief is that "sweating out" a hangover will help see off the effects of a night on the turps faster than lying on the couch clutching your head and groaning. After all, exercise gets your blood pumping, helping your liver remove toxins.
The expert's verdict
Former professional triathlete Rod Cedaro holds a master's degree in exercise physiology and has 25 years of experience in exercise science and human conditioning. He says adequate hydration is the key issue with strenuous exercise and that because alcohol is a diuretic (meaning it dehydrates us and removes essential electrolytes), training with a hangover can be a recipe for disaster.
"Thirst is not a good indicator of how much our bodies need, fluid-wise," Cedaro says. He knows of several instances in which people have done fun runs after a big night of drinking and have collapsed before the finish, required hospitalisation and suffered serious health issues.
Thermoregulation (how your body controls its temperature) is impaired when you're dehydrated, Cedaro says, meaning that if you're not careful, your body can cook from the inside if you're exercising when dehydrated on a hot day. He also says replacing fluid lost through sweat is not just as simple as drinking a glass of water.
"Water sits in the gut and doesn't clear through the system as fast as fluid with sodium, some carbs and, some research suggests, a small amount of protein," he says, and recommends sports drinks that are better formulated to rehydrate your body quickly and effectively.
Your reaction time, hand-eye co-ordination, steadiness and balance will be affected if you're hungover — not preferable if you're on your bike for a training ride, for example.
You're more likely to experience delayed onset muscle soreness if you're dehydrated and your metabolism changes when you're hungover, too, Cedaro says. "If you're exercising to try and burn some fat, your body will actually burn carbohydrate."
The bottom line
Gentle exercise with adequate hydration before, during and after the session is the way to go. Cedaro also points out the best way to avoid the potential complications of exercising with a hangover is to avoid a hangover in the first place by not drinking to excess. But if you do, limit the duration and intensity of the workout, rehydrate with a good sports drink and give yourself time to fully recover before trying to train hard once more.