Coffee can help athletes replenish energy, scientists discover


Sydney: Coffee helps athletes replenish vital energy nutrient, new research from Australia has found.

In a study published in the online edition of the Journal of Applied Physiology, scientists proved that glycogen — which is used for muscle energy during exercise — is replenished more quickly when athletes ingest both carbohydrate and caffeine following exhaustive exercise.

The study was done by eight researchers in Australia and John Hawley was the senior author.

“We think it’s working because whatever the caffeine has done, is create an environmental situation external to the muscle that is helping the muscle soak up like a sponge more glucose,” Hawley said in a phone interview.

The study was conducted on seven well-trained endurance cyclists who participated in four sessions. The participants first rode a cycle ergometer until exhaustion, and then consumed a low-carbohydrate dinner before going home. This exercise bout was designed to reduce the athletes’ muscle glycogen stores prior to the experimental trial the next day.

The athletes did not eat again until they returned to the lab the next day for the second session when they again cycled until exhaustion. They then ingested a drink that contained carbohydrate alone or carbohydrate plus caffeine and rested in the laboratory for four hours.

During this post-exercise rest time, the researchers took several muscle biopsies and multiple blood samples to measure the amount of glycogen being replenished in the muscle, along with the concentrations of glucose-regulating metabolites and hormones in the blood, including glucose and insulin.

The entire two-session process was repeated seven to 10 days later, swapping over the study groups.

“One of the things that the caffeine did was increase blood glucose and insulin levels above carbohydrate alone, so it has an additive effect,” said Hawley, who is with the Royal Melbourne Institute of Technology University in Bundoora, Australia.

“Just think of the muscle looking for substrate to soak up. The muscle is depleted. Its job now is to put back fuel as quickly as it can. The only way that it can do that is to have fuel in the form of glucose in the blood. So the muscle is looking around and not seeing anymore glucose in the blood with caffeine, but it’s seeing more insulin.”

Insulin is the hormone that transports glucose into the muscle.

Hawley said multiple studies have shown the benefits of caffeine for athletes, whether it’s ingested before or during exercise.

“Caffeine is a positive performance enhancer for events as short as 5 minutes and right up to the Iron Man triathlon,” Hawley said. “It is a drug, so I’ll have to call it a drug, but it is legal. It is one of the few drugs that works over a wide range of performances.

“Most of the other drugs or food supplements or nutrients like creatine for example, only work in very short intense sprints or something like that. But caffeine is this mysterious one that appears to have multiple effects, and that’s because it has multiple physiological effects and central-nervous system effects.”

Hawley noted that some Tour de France riders switch to Coca-Cola during the last part of their stages. Frank Shorter, who won the gold medal in the marathon at the 1972 Olympics in Munich, drank de-fizzed Coke during the race.

“He was light-year ahead of the scientists,” Hawley said. “He knew even then that some mixture of caffeine and carbohydrate was very, very good. … That shows that athletes are often a step or two ahead of us.”