Liquid assets for sports people: Hydration and DIY sports drinks

Are you...

• so exhausted that you have to stop running?
• cramping up during training sessions?
• dizzy during workouts?
• suffering from brain fog?

We've just had another summer of record temperatures, with hospitals seeing a marked increase in heat exhaustion cases. But it's not just warm weather that should have us considering our hydration status. You can sweat in the cold and in the pool without realising.

Sweating keeps your body temperature down to within a safe range. Long periods of intense exercise, lifting heavy weights in a hot gym, or training in warm weather are common situations that will see athletes working up a sweat so you must replace lost fluids. Without them, you'll see decreased endurance, strength, and overall performance. Severe dehydration has very serious consequences, but preventing dehydration is pretty straightforward.

How do I know if I’m dehydrated?

Symptoms of dehydration include:

• dizziness or light-headedness
• headache
• tiredness
• dry mouth, lips, and eyes
• muscle cramps
• passing small amounts of urine infrequently (less than three or four times a day)
• dark coloured urine

When should I drink and how much?

Keeping hydrated not only involves providing the body with enough fluids to function during exercise, but also to prevent subsequent injuries and illnesses. For sessions lasting over an hour, you need to drink fluids before, during, and after exercise.

Before exercise: If you suspect that you’re dehydrated, drink 500–600ml of fluid a couple of hours before a session.

Tip: Your urine will tell you if you’re down on fluids. It should be a pale yellow colour. Dark shades indicate increased dehydration.

During exercise: Match your fluid intake to your sweat rate. The hotter you are the more you sweat, so the more fluid you need.

Tip: "Where there's sodium there's water". Add a small pinch of salt to your water bottle to help retain fluid. You sweat out sodium, so you need to keep levels of this electrolyte up as well as fluid.

After exercise: Post-exercise hydration aims to correct fluid losses. You’ll need water to restore hydration, carbs to replenish muscle energy, and electrolytes for rehydration and to keep your muscle function at maximum output. This will be important if you’re going straight into another session.

For rapid recovery, steadily drink at least 500ml of fluid for every 500g of body weight loss - just not at once, unless you are really thirsty, to avoid over-hydration.

Tip: Get on the scales, in your underwear, before a regular session and again afterwards. The difference in weight should approximate sweat and urine losses. Ensure you don't lose more than 2% of your bodyweight - that’s 2kg for a 100kg athlete.

Listen to your body

There’s no 'one size fits all' approach to hydration. For lower intensity sessions lasting under an hour, just listen to your body. There’s less likelihood of dehydration if you regularly take fluids on board. Remember that, if you’re thirsty, then your body is telling you it's already dehydrated. On the other hand, excessive fluid intake can dilute your body’s electrolytes, which help to regulate hydration and keep muscles functioning, so don’t force yourself to drink.

What to drink?

You’ll have seen the advertising for sports drinks. Here’s what the terms mean;

• Hypotonic drinks are absorbed faster than plain water and have some carbohydrate in them for fuel. Focuses on rehydration when you don’t want a high carb intake.
• Isotonic drinks are absorbed as fast as (or faster) than plain water and contain more carbohydrates than hypotonic drinks. They should provide a balance between rehydration and refuelling. Good for daily training needs.
• Hypertonic drinks are absorbed more slowly than plain water, with higher amounts of sodium and carbohydrates to top up muscle energy after exercise. These tend to be used alongside Isotonic. If you sweat heavily or exercise for longer than two hours, opt for a sports drink that contains electrolytes, particularly sodium.

How to make a DIY isotonic sports drink 

Drinks such as Lucozade Sport are simply carbohydrate, water, and electrolytes. To make your own Isotonic drink, mix 500ml fruit juice + 500ml water + a pinch of salt; or 200ml fruit squash + 800ml water + a pinch of salt.

Milk as a recovery drink. Did you know?

Research from Northumbria University found that when semi-skimmed milk is drunk directly after training, it’s an effective and inexpensive alternative to commercial recovery drinks.

It rehydrates effectively, and can even help to alleviate symptoms of delayed-onset muscle soreness (DOMS). Approximately 20g of protein is needed to maximise muscle protein synthesis after exercise, and 600ml of milk hits this target while also providing about 30g of carbohydrate, helping to replenish muscle energy stores.

References

• Bean, A. (2013). The Complete Guide to Sports Nutrition. 7th edn. London:Bloomsbury Publishing Ltd.
• Burke, L. (2007). Practical Sports Nutrition. 1st edn. Leeds:Human Kinetics Europe
• Cockburn E, Robson-Ansley P, Hayes PR, Stevenson E. (2012). ‘Effect of volume of milk consumed on the attenuation of exercise-induced muscle damage.’ European Journal of Applied Physiology, 2012 Sep;112(9):3187-94.  [Online] Accessed 9 October 2016.
• Decker, M. ‘The Effects of Hydration on Athletic Performance’. Undergraduate Research Journal for the Human Sciences: Special Edition. Current and Potential Practices in Athletic Training. [Online] Accessed 9 October 2016.