Rehydration – because exercise is thirsty work!

Have you ever felt suddenly tired and wiped out during training?  Do you ever get headaches during training?  Do you ever feel nauseas during training? You may be dehydrated!  

Why? When you exercise, your muscles generate heat, causing a rise in your body temperature – your body’s clever cooling mechanism is sweating; this is a very effective mechanism but it requires you to replace the fluid that you have lost.  The extra workload and heat in your body makes it work harder, placing extra strain on your heart, lungs & circulatory system, resulting in the heart having to work harder to pump the blood around your body.  This strain means that the exercise becomes much harder, and your performance WILL drop.

Some sobering facts:

A loss of just 2% in your weight (from fluid loss) = affected ability to exercise, with your maximal aerobic capacity falling by 10-20%.

A loss of 4% = nausea, vomiting & diarrhoea.

5% loss = decreased aerobic capacity of up to 30%.

8% loss = dizziness, laboured breathing, weakness and confusion.

More = potentially serious consequences including hallucinations, circulatory collapse & heat stroke.

So....

Drink before your training – aim for 400-600mls around 2 hours before training (this gives time for the fluid to pass through the body too!)  This is not easy before a morning training session – fluid doesn’t just come from drinks remember – many fruits have a high water content; you can also include the milk on your cereal as a fluid etc.

Drink during training – drink as much as you comfortably can (it is not good to feel ‘bloated’ with fluid before or during training) – the ACSM (American College of Sports Medicine, 2000) recommend 150-350mls every 15-20 minutes (if drinking during exercise makes you feel nauseous, you may well already be experiencing dehydration).

Drink after training – there are some very technical ways of calculating exactly how much fluid you need to replace, but essentially, you must drink after exercise!  This does not mean taking too much fluid on too soon – drink as much as you feel comfortable to straight away, then continue to drink regularly.  Full fat milk is a good choice of post-training drink, particularly for younger swimmers, to increase calcium levels that are essential for bone development.

Choose your drink based on what you enjoy – water is good at any time, but before, during and after training you may need to replace other essential nutrients too, so sports drinks can be very useful, along with diluted fruit juice.

Any questions on your training nutrition?  Please just ask!