Nutrition / Food

How Caffeine Affects Your Workout

Using caffeine to fuel up before your workout? Here's what you should know.

Athletes have long lauded caffeine for better workout performance, but experts say even the average joe may benefit from it. Caffeine functions as a stimulant, which means you’ll experience an increased heart rate, more blood flow to your body, and an extra dose of oxygen to your muscles when you consume it.

Check out the five ways caffeine can energize your workout routine—and learn how it could complement your fitness plan.

When it comes to caffeine and exercise, a little goes a long way.

“Caffeine is caffeine regardless of how it is ingested,” explains Dr. Terry Graham, Professor Emeritus in the Department of Human Health and Nutritional Sciences at the University of Guelph. “Studies using colas, energy drinks, or a sports drink with caffeine added, all show a positive effect on exercise performance. The most interesting thing is that some of these have provided quite low amounts of caffeine, as low as 1.5-2 mg/kg and there is still an effect.”

While several studies have shown coffee to have a positive effect on exercise, Dr. Graham says not all research can prove it, and most don’t compare different sources of caffeine. Still, the key caffeine’s impact is how much you ingest, not necessarily the type. Up to 400 milligrams (mg) of caffeine a day is deemed safe for most healthy adults, but when it comes to exercise, Dr. Graham notes small amounts are more than sufficient to give you a pep in your step.

Caffeine can increase endurance, and make your workouts feel easier.

Whether you prefer elliptical sessions at the gym or running on your favorite trail, caffeine can increase endurance up to 30 percent as well as improve your speed by 2-5 percent.

“Caffeine can increase endurance during aerobic exercise,” says Dr. Graham. “Caffeine may also help with speed.”

Even if you prefer shorter, HIIT workouts, caffeine can still have a positive effect because it reduces feelings of exhaustion and pain. With caffeine, your body’s muscle consumption of glycogen (stored energy during exercise) decreases, which forces you to use fat reserves as energy and results in delayed muscle fatigue. University of Illinois scientists also found that consuming two to three cups of coffee an hour before a 30-minute high-intensity workout minimized perceived muscle pain.

The outcome? Your body works harder to build strength and last longer during exercise, but it feels more manageable.

It may not burn fat, but caffeine helps you burn more calories.

Though caffeine is frequently touted as a fat burner, Dr. Graham claims there is zero proof. “The studies that were and are used to produce such statements show that caffeine increases fatty acids (the useable/oxidizable form of fats) in the blood,” he says. “There is absolutely no doubt that this occurs. However, the body ignores these ‘extra’ fats and does not oxidize them. Think of a situation where you are heating your house with a wood stove and have lots of wood in the wood room, then Dr. Caffeine brings you a whole truckload of wood and puts it close to the house and stove. You already have lots of wood, so you have no need for the extra. You ignore it.”

Either way, consuming coffee before exercise could allow you to burn up to 15 percent more calories for three hours afterward, and another study indicates that drinking coffee prior to a workout simply makes the exercise more enjoyable.

Timing matters: before a long workout is best.

Caffeine takes about 30 minutes to kick in, so the timing of when you imbibe matters if you’re seeking improved workout performance. You should also skip caffeine at least six hours before bed to prevent sleep issues. Dr. Graham doesn’t recommend caffeine after a workout, as there’s no known benefit and he says only a few studies have shown that taking caffeine during a workout is effective. That’s why most people experience the benefits of caffeine during a workout when they imbibe before they get moving.

Dr. Graham also cautions against using caffeine as a specific tool for exercise. “Yes, caffeine increases one’s endurance and hence you can get a bigger training effect from the workout. However, I see very few people who exercise or train hard enough to reach true exhaustion. They do their workout and go home; they have not pushed to their limit. Would caffeine ‘help’ them? Yes, as it reduces perceived exertion, but they could also simply work harder. The majority of people have little to no need for caffeine for exercise specifically, unless they are training or competing.”

Metabolism varies, so listen to your body.

“There is no specific amount [of caffeine] to avoid, as people metabolize caffeine at widely different rates,” says Dr. Graham. “There also appear to be some individuals who do not respond positively to caffeine. For most people, ‘too much’ caffeine produces reactions such as being nervous, distracted, and not being able to focus.”

Keep in mind: caffeine can be a laxative for some people with certain sensitivities, and it is also a diuretic. Drinking too much of it, especially in conjunction with working out, can lead to dehydration and fatigue—two results that will actually decrease your body’s ability to perform. If you’re not sure of your hydration level, check the color of your urine.

The Bottom Line

So even though caffeine before a workout can absolutely help you power through exercise with less fatigue, it’s important to be mindful.

Food Nutrition


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