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28.02.2012


Dried apricots vs. jam sandwiches: endurance sports study

While health fanatics are becoming increasingly wary of fast carbohydrates, endurance athletes remain faithful to their pasta, white bread and energy drinks. Why is this, we wondered after reading a study done by sports scientists at the University of Thessaly, published in the Journal of the International Society of Sports Nutrition.

Study
The researchers devised an experiment with 8 male students. The students had to perform the same exertion protocol three times: they were first given food, then waited half an hour and then cycled for 60 minutes at 65 percent of their VO2max a moderately intensive speed and finally cycled at 90 percent of their VO2max until they reached their point of exhaustion.

On one occasion the researchers gave their subjects nothing to eat [Control]. On another occasion the students were given 1.5 g fast carbohydrates, in the form of white bread with jam, per kg bodyweight [HGI]. Glycaemic index: 70. On the third occasion the subjects were given the same amount of carbohydrates, but then in the form of dried apricots [LGI]. Glycaemic index: 30.

The Greeks wanted to work out which type of carbohydrates boosts the brain's production of endorphins the most and whether this has an effect on sports performance. They hoped that carbohydrates with a high glycaemic index would induce a higher endorphin production. After an hour of cycling a moderate tempo the carbohydrates would have disappeared form the blood, but the endorphins would still be there. And these natural painkillers would then extend the time to exhaustion during the intensive part of the protocol.

Results

Things didn't turn out as expected. The type of carbohydrate ingested had no effect on endorphin production. And although the differences were not statistically significant, the students cycled for longer after eating dried apricots than after eating a jam sandwich.


Dried apricots vs. jam sandwiches: endurance sports study


Dried apricots vs. jam sandwiches: endurance sports study


Dried apricots vs. jam sandwiches: endurance sports study


After the HGI-carb meal the students did indeed have more glucose in their blood [the black circles] than after the meal with LGI-carbs [triangles], but in terms of total carb and fat burning [substrate oxidation] it made no difference what the students had eaten.

The researchers suspect that they gave their subjects too few carbohydrates. A higher amount of HGI-carbs may have resulted in better performance, the researchers think.

Speculation
We on the other hand think that after a higher intake endurance athletes would probably perform better on apricots than on a jam sandwich. All we need to do is look at their nutritional value. [nutritiondata.self.com: Bread, white] [nutritiondata.self.com: Strawberry Jam] [nutritiondata.self.com: Apricots, dried]

Source:
J Int Soc Sports Nutr. 2011 Oct 20;8:15.

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