We all know how important it is to be properly hydrated when exercising but can you get too much of a good thing?

Many runners think that you need to drink lots of fluid before, during and after running, especially over the longer distances. Whilst marathon hydration is important drinking excessive amounts of water or sports drinks can put you at risk for potentially serious health problems. Over drinking dramatically increases the risk of hyponatremia. It is vital not to over drink before a run, because doing so can lower blood sodium even before the run begins. Also, don’t over drink during or after the run. Hyponatremia is a condition that occurs when the level of sodium in the blood drops. Over hydrating can cause this by diluting the blood.

Symptoms of hyponatemia include nausea, vomiting, headache, confusion, loss of energy, muscle weakness, spasms or cramps, and in extreme cases seizures, unconsciousness and coma. Dehydration is more common and can be just as serious. Dehydration not only effects performance but also increases the risk of heat illnesses, such as heat exhaustion and heat stroke. Symptoms of dehydration include headache, fatigue, dizziness, nausea, muscle cramps, weakness, irritability, vomiting, heat flush, abnormal chills.

So what is the best thing to do? Well it all depends on how thirsty you get. Experts recommend that runners drink only when thirsty. Listening to your body is probably the best guide. When you need more fluid you get thirsty. If you are not thirsty then you do not need to drink. If ,after a run you weigh more than when you started then you have drunk too much.

As part of your marathon training schedule you will be experimenting with which drinks to use. Once you have found a sports drink that suits you it is best to stick to that drink. A sports drink is better than water as they contain carbohydrates and electrolytes that speed absorption of fluids and can give you an energy boost. The carbohydrate energy will fuel your active muscles, and the electrolytes will help replace some of what is lost in sweat. But remember don’t over drink any fluid. Diluting sports drinks with water or alternating drinks between a sports drink and water will only dilute the benefits of the sports drink. This in turn will have the effect of lowering your sodium levels.

Paying attention to your marathon hydration as you are preparing for a marathon will ensure you are hydrated without suffering from hyponatremia.