Athletes are now spoilt for choice when it comes to the plethora of sports drinks on the market. With varying osmolality, electrolyte composition and carbohydrate levels there are many considerations an athlete must make (including flavour and personal tolerability) when choosing the appropriate sports drink.

Historically, the key consideration in choosing a sports drink was the carbohydrate level, provided by sugars, including glucose, glucose polymers, sucrose and fructose. Sports drinks have a total carbohydrate concentration of 4-8% and most market-leading sports drinks use a combination of sugars to provide the carbohydrate. Recently however, we are seeing more drinks on the market promoted as sports drinks or sports waters with low or zero sugar.

So what does the latest science say about the role of sugars in sports drinks?

It is easiest to answer this question in two parts, based on the two main roles of a sports drink, the provision of carbohydrate and fluid.

1. Carbohydrate for energy and performance

Decades of research has consistently shown that carbohydrate intake during exercise can enhance performance in endurance sports and high-intensity sports. Specifically, sports drinks have been shown to enhance performance in the following situations; 60+ minutes of high intensity exercise or intermittent high-intensity exercise and 90+ minutes of constant lower intensity exercise.

Sports drinks are unlikely to benefit performance when exercising for less than 60 minutes.

Research suggests that the benefits in performance from carbohydrate intake during exercise can be attributed to; maintaining blood glucose levels (preventing hypoglycaemia), providing additional fuel, and via central nervous system effects.

While research on the effect of the glycaemic index of carbohydrates consumed during exercise continues, most athletes prefer moderate to high GI options, such as sports drinks.

The ideal source of carbohydrate in sports drinks is still being investigated but evidence to date suggests carbohydrate blends, as used in most sports drinks, may maximise carbohydrate absorption

2. Provide fluid (and electrolytes) for hydration

Research shows that fluid intake is enhanced when beverages are cool (around 15°C), flavoured and contain sodium (salt).

Most sports drinks contain 10-25mmol/L of sodium. Sodium is an important electrolyte replacement so assists with hydration, but also aids in the absorption of sugar and stimulates thirst, encouraging the athlete to drink more.

It is primarily the fluid and electrolyte component of a sports drink that facilitates hydration, therefore, a sports drink with low or no carbohydrates (i.e. ‘Zero sugar’) may be a suitable option for athletes who do not require additional carbohydrate.

Summary

A low or no sugar sports drink or sports water will assist with hydration so may be a suitable choice for athletes exercising for less than 60 minutes or endurance athletes who prefer to eat carbohydrate in solid foods. Sugars provide the carbohydrate in sports drinks, which may enhance performance for endurance (90+ minutes) and high-intensity (60+ minutes) sports.

REFERENCES

1. Burke & Deakin (2007). Clinical Sports Nutrition. 3rd edition. McGraw-Hill, Sydney.
2. Burke L, Hawley J, Wong S, Jeukendrup A. Carbohydrates for training and competition. Journal of Sports Sciences 2011; 29(S1): S17-S27.
3. Shirreffs S, Sawka M. Fluid and electrolyte needs for training, competition, and recovery. Journal of Sports Sciences 2011; 29 (S1): S39-S46.
4. Sports Dietitians Australia, June 2011. Sports Drinks Factsheet. Available at: http://www.sportsdietitians.com.au/resources/upload/files/110616%20Sports%20Drinks%20PV(1).pdf
5. AIS Sports Nutrition (2009). Fluid- Who needs it? Available at: http://www.ausport.gov.au/ais/nutrition/factsheets/hydration/fluid_-_who_needs_it 

Reviewed by Kath Fouhy, who is a Senior Performance Nutritionist at High Performance Sport New Zealand. She is the lead nutrition provider for NZ Hockey (women’s); the Football Ferns and Paralympics NZ.