Tuesday, May 6, 2008

Running in the heat

Your fluid intake does not just have to come from the tap. It’s a hot, sultry, sunny day. Your body is crying out for liquid. What could be more refreshing than a sweet, succulent slice of watermelon made up of 97% water or a melon and ginger zinger smoothie?

Summer's here at last. We no longer battle our way through howling gales and driving rain. The days are longer. It’s not so hard to prise ourselves out of bed for those early morning runs. Training can be a real joy. Anyone who has trained for an autumn race will agree that running during the summer months can be a truly wonderful experience.

But there is a fine line between that perfect sunny day and a sun so hot that your run becomes a sweaty nightmare. The heat increases, your core body temperature rises and you start to sweat profusely. What is more, this triggers a rapid dispersion of blood into the capillaries of your skin and the amount of fluid available to the muscles is reduced. Your muscles are being pushed to capacity but they are receiving fewer nutrients. You start to slow down. I have mixed memories of my 18 and 20-mile training runs on holiday in the Spanish Pyrenees. We would start running before sunrise, stunned into silence by the beautiful scenery around us, the temperature very comfortable, hardly believing that we were able to run in such an amazing place. We would finish in a state of near exhaustion with the sun beating down on us as the heat of the day began to kick in.

Have you ever felt so exhausted that you have had to stop running? Do you sometimes feel dizzy or disorientated during a long run? Have you ever been overcome by cramp at mile 20? These are all signs of dehydration rearing its ugly head. Running in hot weather can have adverse effects on your body and ignoring symptoms can both inhibit your performance and lead to serious consequences. Even the most well-conditioned athlete has to be careful when running in hot conditions. When my very best running buddy collapsed at the finish line of the Flora London Marathon in April, it struck me more than ever that if we are pushing the boundaries of our physical and mental endurance we really need to be serious about our diet and drinking strategy - not just to help us run more effectively, but also to prevent injury, exhaustion…..or even worse. After 30 minutes in the medical tent, my buddy was fully recovered, if a little shaken, having been given a “magic drink” and some very welcome massage. Digging a little deeper into why this should have happened to a fit, well-trained athlete who had eaten a good pre-marathon diet, I discovered that in fact he had taken in very little fluid - not only during the race, but also during the week running up to the race. He had been so set on beating his PB (which he missed by 8 seconds) that he had only taken the odd sip of water at the drinks stations, plus a gel at mile 6! Had he taken the time to grab a sports drink or an orange segment or two, perhaps he would have made up those vital seconds…

Avoid the worst effects of running in the heat:
Time your runs carefully and think ahead
Choose your route carefully, take enough fluid with you, schedule your runs so that you do not run in the heat of the day and wear the light clothing. Set off before sunrise. If that is just too early for you then try to get out before the sun has had time to heat up the ground. In the evening you will often find that by the time it has cooled down it is so late that you have lost the will to run. Choose a route with trees to shade you and, if possible, avoid tarmac which really soaks up the heat.

If you are not accustomed to running in the heat, you need to get your body acclimatized before you attempt anything too adventurous. Start your runs slowly, don’t run too far and let your body get used to the heat. If you are planning to race in a hot country get in some training in similar conditions.

Take hydration seriously
Each person has an individual requirement for fluid - body weight, gender, climate, running speed, terrain and sweat rate are just a few variables. As runners, we have to learn to recognize the early warning signals of the detrimental effects that running in the heat can have, both on our bodies and on our running. The basic aim is to avoid either dehydration (fluid loss from under-drinking) or hyponatremia (low blood salt level due to abnormal fluid retention from overdrinking).

We need to try to keep our fluid levels topped up all day, not just during our workouts. A basic rule is that the heavier you are or the faster you run the more fluid you will lose. The British Dietetic Association guidelines state that the average person should drink 2.5 litres of water and that this intake should be increased during hot weather or during and after physical activity. But it is really important to remember that water alone is not enough when it comes to replacing fluid lost through sweat. Just taste your skin after a long sweaty run – it is incredibly salty. Your sweat is made up of electrolytes which are vital for your body to function properly, such as sodium, potassium, chloride and magnesium. When you sweat, you lose approximately 2.g to 3.4g of sodium per litre of sweat and you can actually lose up to 1 litre of sweat per hour during a race. For this reason, it is recommended that you drink a sports drink with sodium and electrolytes in it, rather than simple water, when running for more than an hour.

Water intoxication (hyponatremia) is occurring more frequently as greater numbers of recreational sports enthusiasts take part in long-distance events. When the 22-year-old fitness trainer tragically died after completing the London Marathon in April 2007, the condition became more widely known. Hyponatremia is caused by drinking so much water that the sodium concentration in the blood becomes diluted to the extent that vital body functions are jeopardised. During long runs and endurance races a sports drink with sodium and electrolytes will help prevent this happening. When it is really hot make sure that you keep up your salt intake with salty foods or salt tablets to minimize the risk of diluting your blood too much with pure water.

Unfortunately the symptoms of dehydration and hyponatremia are very similar. The tell-tale sign of dehydration is dark urine but other indications are very similar - muscle cramps, disorientation, dizziness, nausea, weakness and extreme fatigue. Stick to a basic rule of drinking before or when you are thirsty and keeping up your salt intake and you should be able to avoid any serious consequences.

I have only ever had one experience of real dehydration and it is one that I never wish to repeat. Traveling in a little-known area on the coast of Columbia as a student, I had been sitting on a bus in the sweltering heat for many, many hours. We had recently flown in from London and I was acclimatised neither to the heat, nor the humidity. Toward the end of the journey I started to feel increasingly nauseous, weak and dizzy. It was only when I climbed down from the bus that I realized that my clothes were soaked through. You could actually wring them out. Too dizzy to walk, I could hardly move. My very sensible friend (later to become my husband!) bought me a litre of water which I immediately downed in one. I then continued to gulp down two further litres. However, it was only after a few mouthfuls of salty chicken broth an hour or so later that I started to feel slightly more alert. If the chicken’s claw had not been protruding out of the bowl, I might have been able to stomach a little more!

Don’t just stick to water; fill your diet with interesting hydrating foods…
“Water is boring and sports drinks are expensive and sickly!” This is a comment I hear all-too-frequently from my running friends. The fact is, however, that you can get your water from many sources other than the tap - on a hot sultry sunny day when your body is crying out for liquid, what could be more refreshing than a sweet, succulent slice of watermelon made up of 97% water? Fruit juices are a great alternative for athletes, because they contain extra calories and vital minerals and vitamins. Raw fruit and vegetables all have a high water content – melon, strawberries, apples, citrus fruits, red fruits, pineapple, kiwis, tomatoes, broccoli, carrots, peppers, spinach, cabbage, radishes...the list is endless. Even some relatively ‘dry’ foods contain a high percentage of water, such as beans, grains like couscous and rice and pasta (foods which expand with water). In hot weather you can very easily base your everyday training diet on foods that include higher levels of water, while still providing your body with the correct level of carbohydrate, protein, vitamins and minerals.

It is good to try to replace some of the nutrients lost after a sweaty run with foods which are high in sodium and potassium. A sports drink is always a good alternative, but these are expensive and sometimes I just really can’t face the sweetness of even the more palatable ones. I often run with a homemade version – ribena with a spoonful of salt, or a few dextrose tablets dissolved in some water, with orange juice and salt (play around with the quantities to suit your taste). Fresh juice, a fruit salad or a piece of fruit straight after a run will rehydrate you, give you carbohydrate to replenish your glycogen stores and will often boost your sodium and potassium levels, along with other essential minerals such as iron, copper, iodine and magnesium and anti-oxidants such as vitamin C, A and E.

If you neither have the time nor the energy to make your own juice, just buy the fruit and eat it. I often chop up whatever fruit is in the house for a fruit salad. I keep it in the fridge and use it at breakfast, for dessert and for snacks. Snacking on fruit and vegetables during hot weather will hydrate you, give you a few extra calories and offer you a welcome alternative to water. Each time you go to the shops, buy yourself a different selection. Frozen forest fruits, raspberries and blueberries are really good for juicing and a cheap alternative to fresh.

See my next post on hydrating recipes for the summer....

1 comment:

Chris Cuvelier said...

Hey there,

As a sports enthusiast who is running around under the hot sun all the time, I appreciate your reminder of how important hydration is. I always try to drink plenty of water, however I find it useful to fill my diet with exciting hydrating foods (like you mentioned) and have found that smoothies are immensely satisfying and nutritious. I am actually launching my own blog with some great smoothie recipe's that I use personally and I think you might enjoy them too... check it out at http://theblenderdiaries.com/

Thanks for the tips on staying healthy and strong!