After losing her initial set of her Hopman Cup match against Flavia Pennetta 6-0, Serena Williams felt like she needed a boost. She asked for a court-side espresso (the judge couldn’t tell if Serena was kidding – she wasn’t), and came back and won the following two sets 6-3 and 6-0. Reporters covering the event were solidly entertained (and they got a good chuckle from the irony of Serena’s opponent sharing a name with a brand of coffee makers).

Does Momma Smash know something we don’t know? Here’s what the research says:

• Sharpening your mind: Research shows that caffeine improves alertness. Studies have also shown that caffeine consumption can improve memory and reasoning in sleep-deprived individuals (like maybe tennis players suffering from ’round-the-world jet lag).
• Improving your exercise: There’s also evidence that caffeine can improve your physical performance. In one study, recreational athletes who consumed 6 mg/kg body weight of caffeine (about five cups of coffee  for a 180 lb male) significantly increased muscle endurance during brief, intense exercise.  Prior to a maximum effort run, caffeine consumption of 5 mg/kg body weight (about 3 cups of coffee for a 130 lb. female) resulted in improved athletic performance among recreational runners.
  400 mg/day, or about 4 cups of coffee, is considered moderate caffeine intake. Those with a heart condition or high blood pressure should talk to their physician about their caffeine consumption.
• Hydration: Historically, athletes have been advised against consuming caffeine because of caffeine’s mild diuretic effect (even though any fluid, including water, has a mild diuretic effect). The Institute of Medicine (IOM) states that caffeine contributes to total daily water intake, so caffeinated beverages can and do contribute to hydration. For more on hydration, check out our hydration brochure. 

Because coffee accounts for 80% of the caffeine in our diet, most of the research on caffeine’s effects uses coffee as a proxy. The Dietary Guidelines Advisory Committee has ultimately decided to make recommendations about coffee, as opposed to a general caffeine recommendation.  The majority of the committee believes that the health benefits of drinking coffee outweigh any risk.

You may not have a ball girl delivering you espresso on the court, but don’t be afraid to get a little coffee-fuel before your next athletic – or mental! – performance.

For more background on what the research says about caffeine, check out our Fact Sheet on Caffeine and Performance and our IFIC Caffeine Review.