Caffeine s influence on our nervous system starts with adenosine !!

Staff Reporter

For two years, Steph Gaudreau gave up her daily cup of coffee. She switched to large mugs of herbal tea — not because caffeine was affecting her sleep or making her anxious, but to gain an edge in cross-country mountain bike racing.

Hoping to enhance the effect of caffeine as a performance aid, Gaudreau, who lives in San Diego, US, drank a cup of coffee on race day as she warmed up. Once that pre-race caffeine boost hit, Gaudreau, now a nutritional therapy practitioner and strength coach, said she felt a sense of euphoria, which helped her feel focussed and mentally prepared for her race. The strategy paid off. In 2010, she took first place in a regional amateur cycling race called the Kenda Cup 

How much of a boost?

There’s a good consensus among scientists that caffeine gives an exercising edge, whether it’s running a marathon, lifting weights or playing soccer, said Nanci Guest, a dietitian, coach and researcher at the University of Toronto in Canada. Guest led a comprehensive review in 2021 of studies on caffeine and exercise.

Whether consumed via coffee, a workout supplement or an energy drink, caffeine tends to improve performance by an average of 2 per cent to 5 per cent, said Brad Schoenfeld, a professor of exercise science at the Lehman College in the New York City borough of the Bronx, US, and director of the school’s human performance and fitness programme. Although caffeine moderately improves anaerobic activities (intense, shorter workouts), such as weightlifting, sprinting and high-intensity interval training, it appears to show the most benefit with aerobic efforts (less-intense, longer exercises), such as swimming, cycling and jogging.

For instance, a 2020 analysis of multiple studies about the effect of caffeine on rowing performance found that competitive rowers actually improved their time on a 2,000-metre row by about four seconds when using caffeine.

“It takes a lot of work to drop your 2,000-metre row, if you’ve been training for a couple of years,” said Mike Nelson, an associate professor at the Carrick Institute for Clinical Neuroscience in Atlanta in the US. “But if you said, ‘Hey, just take this supplement and we can decrease your time instantly by four seconds,’ I’m going to take the supplement.”

This response to caffeine varies from person to person, depending on factors such as genetics, sex, hormonal activity and even diet. “There’s fast metabolisers of caffeine and slow metabolisers of caffeine,” Nelson said.

How does it work?

Caffeine’s influence on our nervous system starts with adenosine, a neurotransmitter that binds to specific receptors and makes us feel drowsy. Caffeine binds to those same receptors, blocking the adenosine from working.

“When caffeine blocks that receptor, the result is a stimulating effect,” Guest said. This, in turn, releases other hormones such as dopamine and epinephrine, which are related to mood, focus and alertness.

Some studies have shown that caffeine also helps our muscles produce more force. Our body needs calcium to initiate muscle contractions, and caffeine helps mobilise calcium ions so they have a greater interaction with the filaments that induce muscle fibre contractions. “Caffeine enhances the ability of muscles to contract at a greater rate and thus would conceivably create greater power,” Schoenfeld said.

Impact on performance

One study found that caffeine intake improved the 5K times of well-trained runners by 11 seconds and recreational runners by 12 seconds.

One study found that caffeine intake improved the 5K times of well-trained runners by 11 seconds and recreational runners by 12 seconds.

For instance, an 8-ounce cup of coffee has about 100 milligrams of caffeine, although this can vary depending on the type of coffee and the method of brewing. So, two cups of coffee for a 150-pound person comes out to 1.3 milligrams per pound.


Although caffeine can help your exercise performance, it does have some adverse effects. “If your performance involves fine motor skills, anecdotally, those people tend to do worse,” Nelson said. If you drink coffee late in the day to help your evening workout, you may be disrupting your sleep.

“People underestimate the value of sleep,” Guest said. Whatever performance gains that caffeine is giving you could be nullified if you are experiencing chronic sleep deprivation. Caffeine also has other side-effects for some people, including nervousness, anxiety and increased blood pressure.

If caffeine does worsen your sleep, Guest recommended taking it about 8-12 hours before bedtime, depending on how quickly your body metabolises the chemical.

For people who aren’t competitive athletes, the benefit of caffeine might be more about going to the gym than performing well there. After all, if your morning cup of coffee is what gets you out of bed, that might be all the performance enhancement you need 

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