It’s estimated that 57% of American adults consume coffee every day. If you are one of those people, you likely rely on a daily cup of joe — and the caffeine it contains — to perk you up in the morning. You may even use it to give you an energy boost before working out or exercising. If you’re tired, but you know you need to exercise, it makes sense. But is it really a good idea?
As a beverage that can and does impact health, coffee has long been studied. However, when it comes to its benefits on exercise, it’s important to understand we are mostly talking about the caffeine that coffee contains.
What is Caffeine?
Caffeine is a central nervous system stimulant. That means it works on your brain, telling it to be alert and also decreasing your perception of effort. Translation: You feel energized and don’t feel pain or discomfort as strongly. Practically speaking, that means you could exercise longer and/or harder when you’re caffeinated, and your brain wouldn’t feel like it was as tough of a workout.
Caffeine’s Impact on Exercise Fatigue
Many studies have looked at caffeine’s impact on sports performance and have found that it positively benefits aerobic endurance by delaying fatigue. With regards to strength training, some studies have found that being caffeinated may increase the number of sets and the amount of weight one can lift compared with a placebo.
It does seem true that having caffeine in your body while exercising could enable you to perform a harder, more challenging workout without feeling it, which has its pros and cons. It’s good because of the obvious: You can work harder and experience better results from your workout. On the flip side, you’re at greater risk for overtraining because caffeine may mask the symptoms of fatigue.
Caffeine and Fat Burning
Another proposed benefit of caffeine is that it enhances fat burning during exercise. This stems from the idea that caffeine may promote the release of fatty acids from fat stores into your bloodstream to be used as a fuel source. However, research has not found this to actually play out, and benefits of caffeine do not include long-term fat burning or better overall body composition. So, this is not a good reason to use caffeine during exercise.
Caffeine is Not Energy
While caffeine does in fact stimulate your nervous system to perceive workouts as less challenging, there is one thing that is does not do: provide real energy. Caffeine is not a substitute for real, legit fuel in your system. “Energy” drinks do not in fact give you energy; they merely stimulate you.
If you haven’t eaten in three or more hours, and you feel your energy slumping, it’s because you need glucose in your body. Before you grab a cup of coffee or an energy drink on your way to the gym, grab a balanced snack or meal, and put fuel in your body.
I like to remind people of one of my favorite slogans: Man cannot live on caffeine alone!
How to Use Caffeine
In the professional sports world, there are some very specific guidelines on how much caffeine you can use to improve performance (more on that later). For the general population though, a dose of 2 mg of caffeine per kilogram of body weight (or about 0.9 mg per pound) about 1 hour before exercising is a good starting place for improving performance. However, since caffeine affects everyone differently, this does not mean that you have to consume this much. It may be better to start with a single serving of your preferred caffeinated beverage and see how it goes.
Depending on what you’re drinking, caffeine content varies greatly. The chart below shares general guidelines, but it’s always recommended you check individual products for the exact amount of caffeine they contain.
|Brewed coffee||8 oz||95–200 mg|
|Espresso||1 oz||47–75 mg|
|Black tea||8 oz||14–70 mg|
|Green tea||8 oz||24–45 mg|
|Cola||12 oz||23–35 mg|
|Diet cola||12 oz||23–47 mg|
|Energy shots||2 oz||200-207 mg|
|Energy drinks||8 oz||70–100 mg|
It’s important to mention that all of the research on caffeine and performance has been performed on adults, so at this time, its use is not recommended for those under age 18. We recommend kids and teens avoid energy drinks because of their higher amounts of caffeine and unknown impact on young bodies.
More is Not Better
It’s important to note that in collegiate and professional sports, excessive amounts of caffeine found in the body are considered grounds for disqualification because it is a controlled substance. So if you compete at an elite level, you need to closely monitor your caffeine levels.
For those of us who are everyday active folks, it’s still important to keep caffeine intake in check. Caffeine can increase your heart rate and blood pressure at rest and during exercise, as well as cause stomach distress. This could cause serious problems in those who have both known or unknown health issues, are sensitive to caffeine or do not consume it regularly.
Caffeine can contribute to insomnia since it stays in the system 8–14 hours. Be mindful of drinking caffeine into the afternoon and evening for this reason. If you feel like you need an afternoon caffeinated drink, first consider whether you actually need food or water instead, since hunger and dehydration can leave you feeling sluggish as well.
To Caffeinate or Not to Caffeinate
The research is clear that caffeine does improve performance in both aerobic endurance and strength training. It’s also considered generally safe for adults to use as a performance enhancer.
However, this does not mean that you must use caffeine to have a great or effective workout. In fact, we would encourage you to ensure you are well-fueled, hydrated and rested first. On days you are really dragging, then maybe consider having a little caffeine, so long as it’s not during an evening workout.
Cook C, Beaven M, Kilduff L, Drawer S. “Acute Caffeine Ingestion’s Increase of Voluntarily Chosen Resistance-Training Load After Limited Sleep.” International Journal of Sport Nutrition and Exercise Metabolism. 2012. 22:157-164.
Duncan M, Stanley M, Parkhouse N, Cook K, Smith M. “Acute caffeine ingestion enhances strength performance and reduces perceived exertion and muscle pain perception during resistance exercise.” European Journal of Sport Science. 2013. 13:392-399.
Rosenbloom C. “Sports Nutrition: A Practice Manual for Professionals,” 5th Edition. 2012. Academy of Nutrition and Dietetics.