Are you carbo-loading unnecessarily?
By Dr Mark Smith | Friday, July 11, 2008 11.00am
Carbs come in many forms Jonathan Gawler
Working muscles must be sufficiently and regularly fuelled during both training and competition in order for sustained power production. The replenishment of fuel stores both within and between workouts must be carefully balanced so that you are able to recover adequately for your next ride.
Our bodies have a plentiful amount of fat, which can be a readily available fuel source during low intensity cycling. However, high intensity sessions of need to be maintained by appropriate carbohydrate intake to meet the requirements of our training and optimise restoration of muscle stores between training sessions.
Getting the right amount of carbs into your body can be a limiting factor in prolonged, high intensity rides. By ensuring adequate intake during periods of increased physical work we can achieve better performance and maximise training adaptations.
Thanks to their ability to allow more consistent and intensive training by promoting recovery between training sessions, reducing interruptions of training because of illness or injury, and enhancing competitive performance, dietary supplements, such as carbohydrate sport drinks, energy bars and gels, are replacing more traditional forms of food.
The use of such exogenous (derived from outside the body) dietary aids to provide sufficient nutritional needs during events that are less than one hour, such as the short-distance time trial or criterium race has been repeatedly reported, anecdotally and scientifically, to improve your performance. Just watching pre-race strategies at your local time trial will highlight individual riders' urgency to down their entire bottle of high-energy fuel in the belief that it will have a performance enhancing effect.
The chances are that performance may be enhanced, but recent research suggests not in the way we think it might. It has been repeatedly questioned in scientific literature, whether the ingestion of exogenous carbohydrate has a significant benefit on performance trials lasting less than one hour. Several investigations have shown there to be an affect over the hour period, but trials shorter that 30 minutes seem not to be affected at all. Over such distances and time periods, the exact mechanism still remains unclear.
Scientists suggest that it is unlikely that exogenous carbohydrate directly influences metabolic activity. Instead, evidence is emerging to suggest that such ingestion may alter our central motor mechanisms within the brain changing our psychological perspective.
To test this theory, a study assessed the use of carbohydrate mouth rinse in order to evaluate whether a performance enhancement occurred over a one-hour cycling trial.
Findings revealed that performance significantly improved following the carbohydrate mouth rinse treatment in comparison with just water. The authors concluded that improvements in performance could not be due to the consumption of exogenous fuel as the carbohydrate rinse was not swallowed. Greater metabolic activity across the two treatments could not therefore be responsible for the enhanced performance.
It was reasoned that the mechanism responsible may involve carbohydrate receptors in the oral cavity, influencing neural commands to the brain that are linked with psychological factors, namely motivation. Although these findings warrant further investigation, they certainly call into question the boundaries between physiology and psychology in performance enhancement, as well as the tendencies of many to down copious quantities of fuels prior to short-distance, high-intensity efforts.
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