What you’ll get…
- Five minutes of reading.
- Ten points about carbohydrates and how they improve performance in team sports!
The need for carbohydrates
In the 1920’s it was found that carbohydrates were an important fuel for exercise. A few decades later, it was discovered that exercise performance and tolerance can be influenced by changing the carbohydrate composition of the diet. Following on from this, in the 1960’s it became clear that muscle glycogen was used during exercise. However, it wasn’t until the 1980’s where they discovered that consuming carbohydrates during exercise can improve exercise performance. Although this is pretty straight forward to us now, it was ground-breaking stuff 30+ years ago…
Since then, the use of carbohydrates to improve sport and exercise performance has become increasingly popular with both recreational and professional athletes across a variety of sports. However, carbohydrates amounts and types commonly get utilised incorrectly by most.
Therefore, how can carbohydrates be used appropriately to aid performance on the field with regards to:
- Pre-game nutrition
- During game-play and half time
- Post game nutrition
Here’s what you need to know…
- Team sports such as rugby and football commonly follow a pattern of play such as; ’stop and go’ which involves moments of high-intensity exercise, followed by lower intensity exercise. For example, three seconds of sprinting with the ball followed by a pass before jogging back into position. Therefore it can be said that team sports are an intermittent based sport that uses both the aerobic and anaerobic pathways for the provision of energy .
- Carbohydrates from the diet (exogenous) and the carbohydrates stored within the body (endogenous) drives exercise performance during training and competition.
- Carbohydrates are primarily stored within the muscles (400-500g/1600-2000kcal), liver (100g/400kcal) in the form of glycogen, and in the blood (4g/16kcal).
- Exercise decreases muscle glycogen and/or blood glucose; the duration and intensity of exercise determines the rate of which your muscle glycogen is used.
- Starting a bout of exercise with decreased muscle glycogen may decrease exercise performance during the latter stages of the game. Therefore, pre-game fuelling becomes paramount during longer periods of play or during events that have repeated competition on the same day; such as rugby sevens.
- It’s advisable that the pre-exercise meal should generally come from higher glycemic (HGI) carbohydrates as opposed to lower glycemic (LGI) carbohydrates. This is due to the LGI meals generally containing more fibre which will be far more satiating – This suggests that the LGI meal will make you ‘fuller’ quicker due to the increased fibre content which brings the consequence of eating fewer carbohydrates and inadequate fuelling. Anecdotally, high fibrous meals can result in gastrointestinal issues such as bloating if consumed pre-games and training.
- Consuming a higher carbohydrate diet during the recovery period restores muscle glycogen and improves repeated performance when training or competing on successive days. In return, reducing the likeliness of point five from reoccurring.
- During training and games, consuming carbohydrates in the form of liquid, gels or semi-solid foods is advised to reduce fatigue. However, this is easier said than done during game play. Carbohydrate type and amount is dependent on the duration and intensity of the exercise in a dose dependant manner. In other words, the longer you train or play, the more you’ll have to rely on the carbohydrates from your diet in order to offset a decrease in performance. With regards to practicality, a 6% carbohydrate-electrolyte beverage (sports drink) on the side of the pitch works best and may prevent a decline in repeated sprint performances and exercise capacity. Interestingly, there is an area where carbohydrate mouth rinsing can be used to improve self selected running speeds, repeated sprint performance and power output during cycling trials when performed 15-20 minutes prior to an event. This option could be viable option to players who struggle with appetite/gastrointestinal distress prior to games, or can be used as a pre-game/half-time strategy to improve performances lasting approximately 30 minutes.
- The effect of carbohydrate consumption during game play is very much dependant on the carbohydrate status of the player. If a player were to start a game in a carbohydrate restricted state, i.e. insufficient carbohydrates consumed prior and reduced glycogen stores then the consumption of carbohydrates during a game will have the biggest impact under fatigue or hypoglycaemia. This would suggest that carbohydrate availability becomes a limiting factor for performance decrements, which if often experienced towards the end of a game.
- Players may experience gastrointestinal discomfort during game play if carbohydrates are consumed in excess – This is due to a reduced rate of gastric emptying. The glucose transporter within the gut (SGLT1) can only absorb a certain amount of glucose before it becomes saturated. This amount is approximately 60g of glucose per hour. Consuming larger amounts of carbohydrates may cause a bottle-neck scenario where carbohydrates will sit in the intestine and cause discomfort. Therefore it is always advised to trial carbohydrate drinks during training to find the appropriate amount for competition. To overcome this and improve absorption rates, a mixture of carbohydrates can be used – However, this is only necessary for endurance events lasting over 2.5 hours.
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