How about a cup or two of coffee before your next sweat session? As with most things, there are pros and cons to chugging a cup of java before exercise. Should you or shouldn’t you? Let’s look at some ways caffeinated coffee can affect your workouts, good and bad.
Coffee Boosts Exercise Endurance
Sipping coffee before an endurance workout could boost your performance by as much as 3%. That might not sound like a lot, but it’s enough to give you an advantage in some events. Another study found that cyclists who consumed caffeine before a 24-mile race generated 3.5% more power during their ride than those who didn’t consume caffeine. That’s a significant difference!
How does caffeine enhance exercise endurance? Caffeine ramps up the activity of your sympathetic or “fight or flight” nervous system. Blood vessels that supply oxygen to your muscles dilate so your muscles can work as hard as possible. The type of energy your cells preferentially use switches too. In response to caffeine, your muscle cells use more fat as an energy source and less glycogen. This shift helps preserve muscle glycogen stores, giving your muscles more reserve fuel and less fatigue.
To get the full benefits, when should you consume caffeine? Studies suggest that you’ll get the most glycogen sparing effects if you drink caffeinated coffee several hours before exercise. The glycogen sparing benefits are strongest a few hours after the caffeine level in your body peaks. Also, even regular coffee drinkers get performance benefits from caffeinated coffee. However, people who don’t regularly indulge in coffee may get greater performance enhancements. Therefore, if you’ll be competing and want to perform your best, eliminate coffee for 5 to 7 days and then restart it the day of the race.
Caffeinated Coffee Can Help You Recover
After a tough workout, you feel fatigued and your muscle glycogen stores might be low. That’s why it’s important to have a post-workout snack that contains protein and carbohydrates. The carbohydrates replenish your muscle’s glycogen stores while protein helps with muscle repair. Some studies find that consuming a beverage with caffeine and carbohydrates boosts muscle glycogen stores more than drinking a carbohydrate drink alone. So, caffeine can help deliver more glucose to your muscles for glycogen storage when you combine carbs and caffeine
Caffeine May Reduce Muscle Soreness
No one likes delayed-onset muscle soreness or DOMS, the muscle stiffness and soreness you feel a day or two after a workout your muscles aren’t accustomed to. Several studies show that drinking coffee at least 60 minutes before a workout reduces delayed-onset muscle soreness and you don’t need a lot of caffeine to get the benefits. In fact, 2 cups of brewed coffee is enough to give you an advantage. It’s not clear how caffeinated coffee reduces muscle soreness. It seems to work at the level of the brain rather than the muscle by changing how you perceive pain.
Caffeine Can Cause Digestive Upset During Exercise
Exercise, itself, can cause indigestion and heartburn in some people and coffee can worsen the problem. One reason is coffee is acidic and can trigger acid reflux in susceptible people. However, dark roast coffee is less likely to cause acidity issues since it contains a chemical compound called N-methyl pyridinium (NMP) that triggers less acid production. Also, cold brew coffee is less acidic. Everyone has a different tolerance to caffeine. Some people have few or no digestive symptoms when they drink coffee, but if you do, exercise could make it worse. So, find out what your individual tolerance is.
Caffeinated Coffee Reduces Blood Flow to the Heart
Caffeine is a performance enhancer because of its effects on the central nervous system. However, studies suggest that it may reduce the boost in blood flow to the heart during exercise. When you exercise, blood flow increases to parts of the body like working muscles, including the heart. Caffeine seems to reduce this boost in blood flow. In one study, only 2 cups of coffee reduced this bump up in blood flow and the impact was greatest when the participants were in a chamber that mimicked a high altitude.
While caffeinated coffee, in reasonable amounts, is unlikely to be harmful to a healthy person, it’s not clear whether it would be a risk for people with uncontrolled hypertension or cardiovascular disease. If you have heart disease or high blood pressure that’s not well controlled, it’s safest to avoid caffeine before a workout.
How Much Caffeine Do You Need?
Should you drink a cup or guzzle an entire pot of coffee? You need not do the latter. Research shows you can get the benefits by drinking between 1 and 3 milligrams of caffeinated coffee per kilogram of bodyweight. It’s safe for most people to consume up to 400 milligrams of caffeine, but if you have uncontrolled hypertension or cardiovascular disease, ask your health care provider before consuming caffeine. And don’t forget to consume some carbohydrates with the caffeine to maximize glycogen muscle stores.
If you’re worried about coffee causing dehydration, don’t be. Research shows you’d have to drink 5 or more cups of caffeinated coffee for it to create a negative fluid balance and dehydration. However, it’s safest not to get caffeine from sources like energy drinks since they contain other ingredients, including stimulants. Combined with exercise, they could be unsafe. Drinking energy drinks can increase blood pressure and trigger an irregular heart rhythm in some people. There have been cases of sudden cardiac death, likely because of a spasm of an artery that carries blood to the heart.
The Bottom Line
Coffee has its pros and cons, but there’s robust evidence that it can improve exercise endurance and performance for sub-maximal exercise, and it may help with recovery too. However, caffeine can have side effects, including anxiety and a rapid heart rate, if you’re not accustomed to drinking it. But you’ll get the most benefits from a performance perspective if you don’t drink it every day so that your body doesn’t develop a tolerance to its effects.
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- Science Daily. “Caffeine Reduces Pain during Exercise, Study Shows”
- Rubach M, Lang R, Bytof G, et al. A dark brown roast coffee blend is less effective at stimulating gastric acid secretion in healthy volunteers compared to a medium roast market blend. Mol Nutr Food Res. 2014;58(6):1370-3. doi:10.1002/mnfr.201300890.
- com. “Caffeine Limits Blood Flow To Heart Muscle During Exercise”
- JAMA Research Letter. “A Randomized Trial of Cardiovascular Responses to Energy Drink Consumption in Healthy Adults”