155-h: MORE CARBS INTAKE DOES NOT IMPROVE A TIME TRIAL PERFORMANCE OF 30 MINUTES

It does not matter for well-trained cyclists whether they take in the two hours prior to a trial of half an hour, 39 or 64 grams of carbohydrate per hour. Compared to drinking only water, in both cases there is a performance improvement of 6-7%. A dosage of 20 grams of carbohydrates per hour, on the other hand, does not seem to lead to a better performance.

CARBOHYDRATES DURING ENDURANCE EXERCISE

The optimal amount of carbohydrates which endurance athletes during exercise should / can take is in spite of the ample research in this area not yet entirely clear. Although the American College of Sports Medicine recommends 30-60 grams per hour, there is evidence that large quantities can lead to better performance. Asker Jeukendrup recently presented at the Science & Cycling conference in Utrecht data showing that highly trained endurance athletes who take 90 grams of carbohydrates per hour and can therefore perform better. A precondition is that different types of carbohydrates are taken in combination, such as fructose and maltodextrin. Researchers from Scotland now examine the effect of taking different amounts of carbohydrates on the time trial performance of 30 minutes.

20, 39 or 64 GRAMS OF CARBS PER HOUR

The 20 trained male cyclists (VO2max 62 ml / kg.min) which participated in this study all did 4 times a simulated trial to ride on an ergometer after they had cycled for 2 hours first in a sub maximal intensity. The planned duration of the simulated trial was about 30 minutes. During the 2 hour sub maximal cycling for this trial the participants had to drink in alternating sequences only water, or 20, 39 or 64 grams of carbohydrate per hour.

In comparison with the prior trial wherein only water was drunk, the performance improvement after taking 39 and 64 grams of carbohydrate per hour was  6-7%. This corresponded to an improvement of the power delivered by 8-9%. Taking 20 grams of carbohydrates per hour prior to the trial did not result in a statistically significant improvement in performance.

FINALLY

the results of this study show that taking more carbohydrates during endurance exercise does not necessarily lead to a better time trial performance. After all, the ingestion of 20 grams of carbohydrate per hour did not lead to a better performance in comparison with only drinking water, while the improvement in performance after ingestion of 39 or 64 grams of carbohydrate per hour was comparable. For most endurance athletes taking 40-60 grams of carbohydrate per hour during exercise is sufficient. In  this study, only 1 type of carbohydrate is used, namely glucose, it is not ruled out that by combining different types of carbohydrates greater performance improvement occurs at higher doses (> 60 grams / hour). With top endurance athletes it seems that this could possibly be the case