Q: Why do I feel sick every time I make a big effort?
A: Welcome to the wonderful world of competitive cycling ? no one said racing was a comfortable ride! Most riders that have raced and pushed themselves to their limit will have experienced variations of nausea and perhaps ?reflux? (heartburn).
I?ve heard some fabulously fantastical explanations describing how lactic acid causes stomach cramps… as well as blurred vision and aching teeth. And in extremely severe exercise (like a hill-climb or kilometre race) there may be a role for blood acidity being a cause of nausea.
But I suspect the predominant explanation is more straightforward. Intense exercise forces a huge shift of blood flow away from the stomach and intestines to the hard-working muscles.
At rest, the gut, liver and kidneys receive about a quarter of the heart?s cardiac output, but this is reduced to as little as one or two per cent during high-intensity exercise and this often causes gastrointestinal distress.
This is more likely to happen if you?re dehydrated so it may help to take on a manageable amount of electrolyte drink beforehand rather than racing on a completely empty stomach. In fact, ?gastric emptying? is faster when there is more fluid in the stomach, not less, and I would recommend experimenting with a weak carbohydrate solution before and during training and racing.
(Sports science lecturer. And Michael Hutchinson?s coach. Need we say more?)