Each participant was recruited to go on a low-carb diet (less than 10% of calories from carbs) for three days on two separate occasions while maintaining their normal training.
On the third day of each three-day diet, the subjects had to cycle for two hours at 75-85% of their max heart rate.
An hour before each trial cyclists were given either a placebo or caffeine (5 mg. per kilogram of body weight) on a randomized, double-blind basis.
This is approximately 340mg for a 150-lb individual.
Blood samples were obtained at rest (prior to cycling) and at 30-minute intervals throughout the exercise period.
Additional blood samples were taken during the first hour of recovery and at 30-minute intervals.
After a washout period of several days, the cyclists went on another 3-day low-carb diet and the test was repeated.
When the body can't find enough glycogen (the form in which carbs are stored) in the blood, it starts breaking down amino acids (protein), which, of course, are the building blocks of muscle.
Some of the by-products of this breakdown include ammonia and urea, so if you find a lot of those by-products in a blood sample, you know that protein is being broken down.
However, by simply taking 5mg. of caffeine per kilogram of body weight an hour before a workout, the cyclists in the study avoided this breakdown.
The researchers theorized that caffeine increases blood glucose so that the working muscles wouldn't have to feed off muscle.
This was further confirmed by the increase in blood lactate levels, which is indicative of glucose being used as fuel (instead of amino acids).
Since we're not professional cyclists nor do we have to meet the demand of that type of training, I think a lesser amount of caffeine will work just fine.
contains 250 mg of caffeine per serving as well as these other benefits.
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