Despite rumours to the contrary it is now summertime and occasionally it does get warm. Runners in last weekend's Edinburgh Marathon were treated to temperatures of mid-high 70s.

It's a timely reminder that any endurance running schedule for 10k or marathon will involve you sweating a lot, and even more so in summer. You don't only lose water, but also important electrolytes and nutrients that make you function better. It is really important to replace fluids to prevent that"run down" feeling.

Replacing fluids need to be done on an ongoing basis and especially during and after long or intense training days.

On a daily basis, you need to drink 1.5-2 litres of water (tea, coffee and alcohol don't count) as a basic requirement taken at intervals throughout the day. When you increase your exercise time this figure should also increase. Try and have a glass or small drinking bottle of water 30-45 minutes before you exercise to ensure you're well hydrated. From a practical point of view this will mean you'll need the loo before you start running rather than inconveniently just after you start running!

Everyone's needs vary, but if you are well hydrated you should be able to run for 45 minutes to an hour without having a drink. Once you start exercising longer than an hour you may need to top up on the run with a minimum of 500 ml an hour, possibly more in hot, humid conditions.

This can easily be done by:

· Taking money with you and stopping to buy water; · Investing in a small"runners feed bottle" to carry with you; · For longer runs buy one of the many bottle belts or Camelbak products that enable you to easily carry larger quantities of fluid.

Also ensure you drink at least 1 litre of fluid within an hour of finishing your run.

Electrolyte supplements and energy drinks can also help keep your body fluids in balance.

For more information:

Energy drinks- www.scienceinsport.com (Science in Sport drinks) www.lucozadesport.com (Lucozade)

Runners feed bottles and hydration systems: www.runandbecome.com

Nb the above information is intended as a general guide. Your ongoing experience will help you discover your personal requirements.