Carbohydrates are a very important nutrient in the diets of all people and are found in foods such as bread, potatoes and pasta. Endurance athletes have high carbohydrate intakes as carbohydrates produce energy that allows them to work for long periods in training and competition.

Carbohydrate drinks are also used by resistance trained athletes in a hope of improving their performance even though there is little research available on the effects of carbohydrate intake on resistance exercise performance.

It is known that muscle glycogen (the body’s stored carbohydrate) is an important energy source for high intensity activities such as weight training. One research study found a reduction in muscle glycogen levels of 26% after a resistance weight training session.

Experts previously believed that glycogen was only used as a source of energy once stored ATP and phosphocreatine (ATP-PC short term energy system) had been used. However, it is now believed that exercise above 100% VO2max will start using glycogen energy stores immediately.

So far, measurements have suggested that reductions in muscle glycogen under these circumstances are not limiting, indicating that extra dietary carbohydrate (in the general diet, or as a supplement while exercising) would not bring about any benefit.

Now though, some sport scientists have suggested there might be a more effect in the muscle which is missed when measuring general glycogen levels. This may be that sub groups of specific muscle fibres could become critically depleted of glycogen.

For this reason a research team at the University of Toledo assessed whether providing extra glucose would have any effect on resistance exercise in seven experienced resistance trained athletes.

The study evaluated the use of a glucose based drink on performance during a resistance workout. In one session the subjects drank a 10% glucose drink and on the other occasion drank a similar coloured and flavoured placebo.

The subjects were required to perform leg extensions, starting with 10 repetitions on the first set, and defining a 'fatigue' endpoint as failure to perform seven repetitions for a set. There was a tendency for better performance after drinking the glucose solution.

The researchers concluded that for athletes performing prolonged resistance exercise (at least 15 sets of 7 to 10 reps) for a given muscle group, drinking a carbohydrate drink could allow a given exercise intensity to be maintained for a longer period of time.

Therefore, extra carbohydrate would be unlikely to have any effect on maximal strength, but could enhance training capacity. They also suggested that athletes involved in multiple bout exercise might benefit from increasing the carbohydrate content of their general diet. The relationship between resistance exercise and carbohydrate fuel certainly merits further study.

Courtesy of PPonline.co.uk

'Effects of Carbohydrate Feeding on Multiple-bout Resistance Exercise', Lambert et al, Journal of Applied Sport Science Research, Vol 5, pp192-197