Used properly, isotonic sports drinks can support performance in endurance events. Joel Enoch explains how, when and why.

The aim of ‘sports nutrition’ products is to replace the energy, fluid and nutrients we lose during exercise. ‘Sports drinks’ usually contain carbohydrate and electrolytes as both of these are used/lost during exercise and as such should be replaced before, during and after training. Here we look at isotonic sports drinks designed for use before and during exercise. Separate products exist for post-exercise consumption – usually known as ‘Recovery’ products – and we will examine these in a subsequent article.

Electrolytes – including magnesium, potassium and sodium – are lost along with water when we sweat. These minerals are important for how cells function within the body and if they are not replaced we may experience a reduction in performance during longer exercise or when sweat rates are high. This would be reason enough for their inclusion.

Additionally, research shows fluids with electrolytes can be more readily absorbed into the cells. This is key as when we think about ‘being hydrated’ we often consider simply how much fluid we have drunk. In reality it is when the fluid within us is where it needs to be (i.e. in and around the cells) that we are hydrated.

Lastly, the presence of these electrolytes can also increase the amount we chose to drink as the inclusion of sodium keeps our thirst response switched on. Research demonstrates that athletes may cease drinking well before they are rehydrated if water is the only available fluid.

Carbohydrate is added to sports drinks as a way of replacing lost energy during high intensity exercise (above about 70% or our maximum effort) as this is when the body uses carbohydrate for energy. Because we can only store a limited amount of carbohydrate in our bodies (around sufficient for 90-120 minutes of exercise), during longer or harder exercise we need to take on board extra energy to maintain performance.

Carbohydrate concentration is also important and should be between 6-8% of the total drink (for normal 500ml drinks this is around 30g of carbohydrate). Less than this and there will not be sufficient energy to maintain performance. More, however, and there is a risk of reducing water absorption and this in turn may increase the rate of dehydration and increase gastrointestinal discomfort. Commercial ‘soft’ drinks fall into this category and it for this reason that they are not ideal for sporting use, especially when dehydration may be an issue.

Although sports drinks are no magic potion for enhanced ability within our chosen exercise, the use of sports drinks is common practice with elite performers and research has long established the benefits they provide in terms of reducing fatigue and maintaining hydration. There is absolutely no reason why the same benefits cannot be had by the recreational and ‘hard core’ amateur athlete. Grab a sports drink prior to your session and see what you can achieve!

Hopefully that's a sports drink in the bike bottle

About Joel

Joel has competed in both European and World Championship Age-Group level triathlons. In 2009 he also raced Elite on two occasions and if it wasn’t for a dodgy zip on his tri suit he wouldn’t have done too badly! This year is his 3^rd ‘once in a lifetime opportunity’ to prove something on an international age-group level and he hopes to win some medals this time around! He has a BSc in Sports Science from Brunel University, an MSc in Nutrition from Bristol University and has been a Sport Scientist for the Lucozade Sport Science Team since the beginning of 2009. He works with both Olympic athletes and people who have never heard of carbohydrate!

Related posts:

1. Triathlon nutrition: can you overdose on sodium with sports drinks? The government tells us to eat less salt. But hard-training...
2. Triathlon nutrition: hyponatraemia – what it is and how to avoid it As part of his regular series on triathlon nutrition, Joel...
3. Triathlon nutrition: Protein AND carbohydrate ingestion during endurance exercise – fact and fiction Joel Enoch continues his series on triathlon nutrition with a...
4. Triathlon Nutrition: SIS Energy and Protein products (Review) Over the last couple of months we’ve had a chance...
5. Triathlon nutrition: MyProtein energy and recovery products (review) MyProtein aim to offer “the widest range of the highest quality...