“To the elite or high-level athlete, it’s going to mean a lot,” Dr. Nelson said.
Studies show that the ideal performance-enhancing dose ranges between 1.4 to 2.7 milligrams per pound of body mass (though some research shows that even lower doses can work).
For instance, an eight-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. It may take some experimentation to find the right dose for you, because people metabolize caffeine differently. Whatever your ideal dosage, be sure to take it about an hour before exercise to allow time for your bloodstream to absorb the caffeine.
“The only thing I would say,” Dr. Guest said, “is that somebody who’s not really executing a lot of energy, like they’re going for a walk, they would probably want to go with a lower dose, because when you’re stimulated, you need an outlet.”
Side effects and tolerance breaks
While 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,” Dr. 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,” Dr. Guest said. Whatever performance gains 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, she recommended taking it about eight to 12 hours before bedtime, depending how quickly your body metabolizes the chemical.
As for Ms. Gaudreau’s strategy of abstaining from caffeine to boost its performance-enhancing effects, a recent analysis of multiple studies found that habitual consumption doesn’t blunt caffeine’s performance-enhancing effects. You might experience a stronger placebo effect if you save your caffeine usage for before a competition. But Dr. Guest also cautioned that the side effects of caffeine withdrawal, like headaches, fatigue and impaired concentration, could affect your training sessions, making you less prepared on game day.
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.
Hilary Achauer is a freelance writer focused on fitness, health, wellness and parenting.
