No matter which sport you choose, it’s essential to have your body in peak condition when it counts. No matter your goals – be it a personal best or a place in the Olympics - allowing your body to achieve peak performance is something all serious athletes strive for. 

The role of sugar in sports has been debated extensively over the past several decades, but what does the most current science say? 

For people who aren’t participating in sports or performing at a high level, often a more nutrient-dense (as opposed to energy-dense) diet is encouraged. If you’re a highly active athlete, however, sugar can provide the fast-acting energy source some athletes need to fuel performance. 

Consuming sugar before exercise or an event

Consuming carbohydrate-rich foods before exercise or an event prepares the body for the physical activity ahead and prevents under performance, distracting hunger pangs and stomach discomfort.  Sugary foods and drinks (like sports drinks and gels) can be a helpful source of compact carbohydrate in the 24 hours before a race or event. These food and drink options can also supply additional carbohydrates for athletes consuming low-residue (low-fibre) foods, thus enabling them to ‘compete light’ on race days. 

Some athletes may perceive a negative effect on their bodies from consuming sugar or carbohydrate-dense foods an hour before exercise.  Sports dietitian Louise Burke states, “In one study, when athletes consume glucose an hour before prolonged cycling they fatigued sooner than when they cycled without eating. Possible explanations include a dip in blood sugar levels after the start of exercise or a faster depletion of muscle glycogen stores”. 

Many athletes experience a possible drop in blood-sugar levels, which could explain the fatigue and shakiness they were experiencing, however, on balance, most studies show that fuelling before prolonged exercise improves endurance and performance, as long as the athlete ensures there is a net fuel gain at the end of the activity.

Consuming sugar during exercise or an event

During shorter periods of exercise (less than 60-90 minutes) it is not necessary to consume carbohydrates during exercise. However, for longer session greater than 90 minutes (e.g. marathons, team sports) there can be a number of performance benefits to carbohydrate intake, including glycogen sparing, provision of an exogenous muscle substrate, prevention of hypoglycaemia, delayed hunger, and activation of reward centres in the central nervous system.

It is important to consider at what point during exercise or an event you consume sugar or carbohydrate foods. This will significantly depend on the type of activity you’re participating in. A golf competition lasting 4-5 hours places very different pressures on the body when compared to running a marathon or competing in an ironman competition. 

Higher intensity exercise will use more of your body's energy, thus burning more sugars and fats. Studies show the higher the intensity level of activity, the more the body relies on glucose as an energy source, since it’s a faster and more efficient fuel than fat. 

Only a limited amount of glucose can be stored in the body in the form of glycogen, so many athletes find that 45 – 90 min of moderate to high-intensity exercise is when they ‘hit a wall’ or start to fatigue. This is where consuming compact carbohydrates like sports drinks and gels can help replenish, or even avoid depletion, of glycogen levels in the body. 

Consuming sugar after exercise or an event

After prolonged exercise, particularly if that exercise is at a moderate to high intensity, your body will (partly) empty its glycogen (energy) stores. It is important to replenish these stores to assist in recovery and ongoing performance. Nutritious, easily-digested carbohydrate foods are advised soon after exercise and at subsequent meals. Incorporating a source of protein will also assist with muscle repair and growth.

If considering the Glycaemic Index of your carbohydrate source, sports dietitian Louise Burke provides some advice. “It is often suggested that high-GI carbohydrate-rich foods are most appropriate for replenishing muscle glycogen stores after strenuous exercise, while low-GI carbohydrate-rich meals are best for a pre-competition meal. Although these ideas aren’t universally true, some athletes in some situations may benefit from choosing foods in a certain GI class. Remember, though, this is just one more piece of the food puzzle, not a universal tick of approval for a particular type of food.”

Everyone’s body is different and has different fuel requirements and energy budgets, so consultation with experts is always advised before drastically changing your pre-, mid- or post-exercise diet and energy intake. 

REFERENCES

• Bourke L & Cox G (2010). The Complete Guide for Food for Sports Performance: Peak Nutrition For Your Sport. Australia: Allen & Unwin.
• Academy of Nutrition and Dietetics, American College of Sports Medicine, and Dietitians of Canada (2016). Position of the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance. J Acad Nutr Diet, 116:501-528.
• Sports Dietitians Australia. Pre-exercise fuelling. Accessed 18 Nov 2020 at https://www.sportsdietitians.com.au/wp-content/uploads/2020/07/Pre-exercise-Fuelling.pdf
• Sports Dietitians Australia. Eating and drinking during exercise. Accessed 18 Nov 2020 at https://www.sportsdietitians.com.au/factsheets/fuelling-recovery/eating-drinking-exercise/
• Sports Dietitians Australia. Recovery nutrition. Accessed 18 Nov 2020 at https://www.sportsdietitians.com.au/wp-content/uploads/2020/07/Recovery-Nutrition.pdf
• Spriet LL. (2014). New insights into the interaction of carbohydrate and fat metabolism during exercise. Sports Med, 44(Suppl 1):87–96.
• Adams P. (2013). The impact of brief high-intensity exercise on blood glucose levels. Diabetes Metab Syndr Obes, 6:113–122.