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Fluid balance and your running
The importance of keeping hydrated when running
Keeping your body well hydrated is a vital requirement for any runner. A lack of water in the body can badly affect your running performance but can also lead to serious health problems and fainting. Water fuels the muscles during a run and is not to be under-estimated. Here's our guide to avoiding running injuries through drinking the optimum amount of water.
You’ve heard it a thousand times; “Make sure you drink plenty of water during a race, or you’ll suffer”. But do you take any notice? Most of us will have been in events and thought; “I feel fine, I don’t need to drink at this stop; I’ll keep going until the next one”. Plenty of us probably don’t drink properly during our running training programmes either. So why is it so important to drink enough water? What is all the fuss about?
The role of water in running
Water plays a crucial role in our well-being; it reduces the impact of toxins through dilution and excretion via the kidneys, carries vital nutrients, regulates body temperature and feeds the organs, including the largest of them all, the skin. We lose half a litre a day through normal body functions like sweating and evaporation and the more we exercise the more we need to replace.
Quantity of water runners require
There have been a number of studies carried out on the amount of water runners need to consume during a race, but what’s clear is that much depends on the environmental conditions, the individual’s metabolic rate and the speed with which they are running. Early studies suggested much greater amounts of fluid than later ones, as new studies discovered other factors that became of increasing importance.
Shephard and Kavanagh (1978) discovered that our glycogen stores actually release water, which therefore plays an importance role in combating dehydration caused by sweating. This immediately reduced the amount of water that was recommended for runners to consume.
Noakes (1985) concludes that; “A runner who sweats at a rate of one litre per hour during a four hour marathon race and who actually suffers a four kg weight loss (1l of sweat = 1kg) during the race would incur an actual dehydration of only 2kg, because 2l of water would be released by glycogen metabolism. Therefore, during the race, that runner needs to drink 500ml/hr to maintain fluid balance”. Even when we’re not running, our normal daily water requirements are one and a half litres a day.
Timing your running water intake
It is clear that runners should drink at every water stop, even if it’s only a few sips and even if you don’t feel the need. It is essential to feed the body throughout the race and not try and make the recommended intake at the end of each hour of the run. It should be a constant process. One of the dangers is to ignore the early stops because you feel good and try and make up for it at the end, when you’re glad of the rest at the drinks station. By then the damage will have been done and the dangers of dehydration, bloating and hyponatremia become very real.
Hyponatremia and running
This is, in effect, water poisoning and takes place when the runner consumes too much water. It’s a problem mainly for slower runners in ultra marathon around the ten-hour mark, although it should not be ignored by marathoners.
This is a condition that can kill, so it should clearly not be underestimated. In essence, it is a dilution of the blood sodium contents that results from too much fluid being ingested. The longer the runner is out on the course, the more opportunity for drinking and the lower the metabolic rate resulting in lower rates of sweating. This combination means the recommended hourly rates of water consumption are easily exceeded and changes in sodium levels and ultimately blood volume are induced.
It is not just during races that you should be aware of your water intake. Most of us have been guilty of training runs where we’ve had no water at all, probably because of the inconvenience of having to carry it with you. Try and rectify that problem as soon as you can; if you’re regularly running over five miles in training you should be drinking at regular intervals.
There are lots of new products on the market now, which make this far less of an issue than it used to be. These include belt holders, with the facility to carry a number of small bottles. Whatever else you do, make sure you’re well hydrated before you start your run.
Don’t be a victim of dehydration on race day or during training and make sure you drink enough, without going to the point of excess. Try and stick to the one and a half litre a day rule even when you’re not training. You’ll be amazed at how much extra energy you’ll have and how much better you’ll feel generally. Go for non-carbonated, filtered water if you can. The cleaner it is the better.