In order to fuel optimal performance you need to be eating and drinking the right things at the right time. This includes before, during and after training and games. Carbohydrates are key.
This chart illustrates the rate that glycogen is used during exercise at 3 different intensities.
As exercise intensity increases, VO2max will increase accordingly:
• 30% VO2max is equivalent to a comfortable walking pace
• 60% VO2max is equivalent to a jog
• 75% VO2max is equivalent to a fast running pace
As you can see, muscle glycogen stores are depleted faster as exercise intensity increases. After 90 minutes of exercise at 75% VO2max, about 80% of muscle glycogen stores are depleted (Sherman et al, 1988).
This slide shows the consequences of not replenishing glycogen stores after an exercise session on subsequent sessions over a number of days.
After a prolonged exercise period the glycogen stores in our muscles will be reduced because glycogen has been used to provide energy during exercise. If we consume a high carbohydrate diet after exercise, our muscle glycogen stores will be quickly replenished and by the time we begin to exercise again the next day, they will be almost back to where they were on Day 1 and we will be able to perform at least as well in our next exercise session.
If we consume a low carbohydrate diet after exercise our muscle glycogen levels will not be replenished and so our next exercise session will commence with inadequate glycogen stores. By the end of that exercise session glycogen stores will be depleted even further.
If muscle glycogen is not replenished, when we exercise on the third day our energy levels are going to be very low and by the end of that session, our glycogen stores will be virtually empty and we will have to rely on fat metabolism for energy. Performance will undoubtedly be impaired. Therefore nutrient timing before, during and after exercise is key.
This is a carbohydrate-rich meal that is eaten about 3 hours before exercise begins. Try eating a bowl of pasta or rice with some meat or veg or a couple of sandwiches and a banana.
Pre match snack
This is a carbohydrate-rich snack eaten about 1 hour before exercise. Try eating an apple or banana with some nuts. Also within 30 minutes of training you should top up your carbohydrate stores by drinking a sports drink or eating an energy bar.
It’s best to drink water as well as 30-60g of carbohydrate per hour of exercise. This can be achieved by drinking 500-1000ml of Lucozade Sport, having 1-2 sports gels or eating a couple of bananas.
The aim is to eat 1g of carbohydrate /kg of body weight per hour for 2-4 hours. So if you weight 80kg you would need to eat about 320g of carbohydrates in the 4 hours post exercises. Therefore you could use the carbohydrate content of foods is the previous post to workout what you need to eat to replenish your muscle glycogen stores.
Sherman, W. M. and Lamb, D. R. Nutrition and Prolonged Exercise. In:
Perspectives in Exercise Science and Sports Medicine, Volume 1, Prolonged Exercise (Lamb DR and Murray R, eds), pp213-280. Benchmark Press, USA. 1988.