How Drinking Coffee Before A Workout Affects Your Performance

Before you start working out, you want to consider how to properly fuel your body. Whether it's food, water, or other beverages, what you consume can affect your endurance and athletic performance. Though coffee may provide energy throughout your workday, how does it affect a workout? 

Drinking coffee before a workout can help with both mental and physical energy levels, exercise science and nutrition expert Shawn Talbott, M.S., Ph.D., says. In fact, he sometimes drinks his iced coffee during a workout.  

"The high content of polyphenols in coffee can help with antioxidant and anti-inflammatory protection, as well as blood sugar balance," he says. Each of these aspects is important for exercise performance and especially for post-exercise recovery and tissue repair.

Along with the polyphenols, the caffeine in coffee has performance-enhancing properties. In an overarching review of caffeine and exercise, researchers analyzed 4,800 people across 300 studies and found that exercise performance increased up to 16% after participants drank caffeine1.

"Caffeine takes about 30 minutes to start working to boost energy levels," Talbott explains, "so depending on the duration of your workout, you can 'time' when you want the caffeine effect to exert itself." 

For short exercises, drink your coffee before you leave the house. By the time you get to the gym and start exercising, the caffeine should take effect. 

For endurance exercises, save your coffee for the last hour. "As an ultra runner and Ironman triathlete," Talbott says, "I save my iced coffee for the later portion of my long workouts." The last stretch of an endurance run or bike ride is when you'll probably need a boost. 

Just keep in mind how coffee tends to affect you. If a morning cup of coffee generally makes you poop, it might not be conducive to cardio. Drinking iced coffee or cold brew instead of hot coffee may help, though, as the warm liquid may increase intestinal motility3 and increase the urge to go. 

A standard cup of coffee contains about 100 mg of caffeine, Talbott says. However, depending on how strong the coffee is, that number may double. 

"That 100 mg of caffeine and associated polyphenols will boost mental and physical performance starting at about 30 minutes and lasting for about two to four hours," Talbott explains, though the exact time depends on your personal ability to metabolize caffeine, which differs between people.

One study found that participants who drank 4.5 milligrams of caffeine per kilo of their body weight4 saw a 15% improvement in athletic performance. For example, a 140-pound person would need to drink 285 milligrams, which is about one 20-ounce cup of coffee.

While some believe that coffee can lead to dehydration during a workout, Talbott says as long as you're properly drinking water, you should be fine.

Drinking too much coffee (about 400 mg or four cups a day) may lead to potential downsides, like over-caffeination. "After 400 mg of caffeine, you start to see the beneficial effects of coffee get replaced with negative side effects," Talbott says. These effects may include high tension or anxiety, heart palpitations, an upset stomach from increased acid production, and increases in cortisol.