Many people who run a marathon get into difficulty if the weather is warmer than usual. This article discusses what every runner should do to avoid problems when running in the heat.

A word of caution:
It's important to remember that over-exertion in hot and humid conditions can be very dangerous. You need to be very aware of the potential heat-related problems you can encounter during a long race like the marathon

Check the weather!
It's marathon day and after a solid training period you're all 'gung ho' and ready to go. But wait, the forecast calls for humid conditions with a high of 80 F (about 27 C) before the race ends. You need to think very carefully about:
• your previous training conditions
• your own susceptibility to heat
• what to wear
• what pace to run

Training Conditions
If you are running a Spring marathon, chances are you were training in (much) cooler weather than race day. Unless you normally run very well in hot weather, then you have to make some tough decisions about your race pace and target finish time. The best strategy is to add an extra 15 minutes or more to your goal time, and if it's warm early on, start out at a pace 30 seconds slower than you had planned. This might be a difficult choice to make but at mile 26 you'll be glad you did!

Susceptibility to Heat
Some people can just run better than others in hot weather. If you on the other hand, suffer in these conditions then you need to bear this in mind and take things easy. Don't try to keep up with someone else.

What to Wear
Every marathoner struggles with this question before the race. Often it can be quite cool at start time, but then warms up considerably three hours later. Your best bet is to have an old T-shirt on top of your singlet. Then you can discard the outer layer as soon as you are warmed up. The best type of clothes to wear for warm weather are the lightweight mesh fabrics like Cool Max. A lightweight hat will help protect your head and face from the direct sun. Lightweight socks will keep your feet cooler.

Race Pace
As we said above, if it's warm at the start, it's best to start out at a slower pace than you normally would. This gives your body time to adjust, and also gives you time to assess your ability in the current weather conditions. If it's cool at the start, then go out at your planned pace but be prepared to slow down before you run into problems as the temperature rises. Don't make the common mistake of dividing your target time by 26.2 to find the exact pace you will run from start to finish. It rarely works!!

Be Prepared
Here are a few things you should do before and during the race:
• Wear Sunscreen
In spring this isn't something we normally remember. But, you'll be out in the sun for several hours and it's very easy to get a bad sunburn, even on a cooler day.
• Drink Water before the race Make sure you are properly hydrated by drinking several glasses of water before the race. Ideally you will have increased your water intake during the whole week prior to the marathon.
• Keep hydrated. Drinking water before the race is not enough! As you sweat you are losing fluid constantly. Don't skip the water stops! Even a couple of mouthfuls helps. It's also a good idea to walk as you take a drink. Later in the race, Gatorade and similar drinks will help prevent muscle cramps. you should take you own fluid replacement drink with you.

Heat-related conditions
• Dehydration - your body has less than the volume of water it requires. Dehydration can occur after only a 2% decrease in the normal water volume. Your throat feels parched and you may have a headache.
• Heat Exhaustion - the next stage is to feel dizzy, sometimes accompanied by muscle cramps, a headache and vomiting. Your skin may feel cold and damp.
• Heatstroke or Hyperthermia - this can be fatal and will follow if the heat exhaustion stage is not checked. The symptoms are disorientation, inability to think properly, dry skin and loss of consciousness.

What to do if you start to suffer from the heat Stop running! Take a walking break if you feel dehydrated and drink lots of water. If you do not recover you need to seek assistance from the course marshals. If you can get out of the sun, this will help. Prevention is better than cure, so it's up to you to recognize the early warning symptoms and take appropriate action.

Conclusion
Hot weather can really affect your marathon performance, and in the extreme, be fatal. To do well in these conditions you have to assess your own ability and adjust your goal and pace accordingly. You will end up running a much better time, and more comfortably than if you stick to your original (cool-weather) goal.

• Run slower (you will finish the race in better shape)
• Take walking breaks to let your body cool down
• Drink at each water stop, take Gatorade or similar.
• Watch out for symptoms of dehydration

The marathon you are running may be important to you but your own well-being comes first!

About the Author:
Mike is a long-time fitness enthusiast, runner and walker. He has completed over 25 marathons and is co-author of the book "Marathon Training Tips". Mike is also the developer of customized training logbooks for athletes http://www.personallogs.com
He maintains a website "26.2" about marathon information and training at http://www.marathon.ipcor.com