Repeated studies have shown that consuming caffeine and carbohydrates before and during workouts improves performance in many cases.  Researchers from Australia have just published a report in the Journal of Applied Physiology that says these substances quickly replenish the fuel supply to the muscles when consumed after a workout, too.

Glycogen is lost during exercise, making muscles feel tired, achy, and depleted.  When study participants downed a carbohydrate-based beverage laced with caffeine after an exhaustive workout, glycogen levels measured 66% higher four hours after exercise than when a caffeine-free carbohydrate-based beverage was consumed.  Glycogen is the primary source of fuel used to power the muscles of the body.

The Australian study involved seven skilled endurance cyclists during four sessions of controlled exercise and food intake.  The first study session involved cycling an ergometer to the point of exhaustion to deplete glycogen levels.  The cyclists ate a low-carb dinner after the workout but didn’t eat again until after a similar workout the following day.  After the second workout, some cyclists drank a beverage containing carbohydrates and the others drank a similar beverage containing carbs plus the caffeine equivalent of five or six cups of coffee.  Neither the cyclists nor the research team knew which athletes were consuming caffeine and which were not.

During a four-hour recovery period, blood samples and muscle biopsies were taken from each athlete.  Researchers measured hormones in the bloodstream, including insulin and glucose, and the concentration of metabolites that regulate glucose.

Approximately one week later, the workout sessions were repeated but the beverages the cyclists drank afterward were switched, so those who had the caffeine-laced beverage the first time were given the beverage that didn’t contain caffeine during the second session and vice versa.  Both beverages looked, tasted, and smelled the same and carbohydrate levels were the same.

The research team reports these findings:

• Both groups measured the same degree of glycogen replenishment one hour after the workout, regardless of which beverage was consumed.
• When the caffeinated beverage was consumed, glycogen levels were 66% higher four hours after working out than they were when the carb-only beverage was consumed.
• Higher levels of insulin and glucose were measured throughout the four-hour recovery period when the caffeinated beverage was consumed.
• Levels of certain proteins which promote glucose transport to muscle tissue was much higher after consuming the caffeinated beverage.

The eight milligrams (mg) of caffeine consumed for study purposes can cause jitters and sleeplessness in many people so researchers anticipate similar studies using smaller amounts of caffeine in the future.  During this study, some athletes did have trouble sleeping the night after drinking the caffeinated beverage but others dozed off even during the recovery period.

The research team cautions any athletes interested in experimenting with carbohydrates and caffeine following a workout to do so long before competitive performance in order to determine how the carb-caffeine combo works on an individual basis.

Members of the Australian research team are affiliated with the Royal Melbourne Institute of Technology University (RMIT), Bundoora, and St. Vincent’s Institute of Medical Research in Fitzroy.

Source: American Physiological Society