Whether you’re getting up early to go to the gym before work or heading to an evening exercise class, you can refuel with a caffeinated drink before exercising.
This makes sense. Coffee, tea, caffeinated sodas, and energy drinks are all popular options to keep you energized. But is it really a good idea to do this before exercise?
Some studies show that small amounts of caffeine can improve certain aspects of athletic performance, but too much caffeine can have drawbacks. The key is to know how much caffeine is appropriate and when to take it.
Caffeine intake: Discover its effects on the body
Caffeine is a stimulant that affects the central nervous system as well as other systems in the body.
It works by changing the way your body processes adenosine. Adenosine is a chemical that helps regulate energy and sleep. It builds up in your brain throughout the day and when it binds to receptors, it makes you feel tired.
Caffeine has a similar structure to adenosine, so it adapts to the same receptors that adenosine uses. When caffeine binds to adenosine receptors, it blocks adenosine from attaching to them. This means that adenosine cannot do its job of making you feel sleepy. As a result, you feel more awake and alert.
These receptors are found in cells throughout the body, so caffeine doesn’t just affect the brain. Caffeine produces a range of different physical and neurological responses, including:
- Stimulates the central nervous system: Caffeine crosses the blood-brain barrier and directly stimulates the brain. That’s why caffeine can make you feel more alert and energized.
- Diuretic effect: Caffeine increases urination.
- Digestive function: Coffee stimulates the release of stomach acid. Some studies show that drinking caffeinated beverages such as coffee, tea, and soda can increase the likelihood of heartburn and stomach upset.
Caffeine is a very potent stimulant. When you consume caffeine, 100% is absorbed. Maximum blood concentrations are reached within 30 to 45 minutes after ingestion, and peak plasma concentrations are reached within 15 to 120 minutes. Caffeine’s half-life in the body is about 4 to 6 hours, which means there may still be traces of caffeine in your blood 12 hours or more later.
As with most substances, caffeine carries the risk of negative effects, especially if you consume more than the FDA-recommended 400 milligrams per day.
The most common side effects are mild and include anxiety, irritability, insomnia, increased urination, muscle twitching or tremors, irregular heartbeat, and gastrointestinal irritation. More serious side effects include cardiac arrhythmias, myocardial infarction, and electrolyte imbalances.
Caffeine is an effective energizer, so it’s easy to have a cup of coffee or tea before exercising. But before you drink an iced latte or high-caffeine energy drink, you should consider how it might affect your body.
What are the disadvantages of drinking caffeine before exercise?
The effects of caffeine on different parts of the body may have unexpected effects on your exercise. This is especially true if you don’t yet know how your body reacts to caffeine.
On the one hand, caffeine can stimulate bowel movements. The exact reason for needing to go to the bathroom after drinking coffee isn’t entirely clear, but some studies show that caffeine boosts hormones that trigger colon contraction.
If this is common for you, you should consider bathroom use when planning your caffeine intake and exercise regimen. For example, consuming caffeine before a run could put you in an awkward position when nature calls. Caffeine’s diuretic effects may also lead to dehydration after strenuous exercise.
Caffeine can also cause insomnia. The effects of caffeine can take anywhere from 2 to 12 hours to wear off, so drinking coffee in the afternoon may mean you’re still experiencing the effects before bed. Experts recommend that you should stop consuming caffeine at least eight hours before you plan to go to bed. So if you’re planning on hitting the gym after get off work, don’t consume caffeine.
If you’re not used to consuming caffeine, it can cause unpleasant side effects, such as anxiety and increased blood pressure, which can negatively impact your performance.
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What are the benefits of drinking caffeine before exercise?
There may be benefits to consuming caffeine before hitting the gym. After all, it is a stimulant, so it can make you feel more energetic. This extra energy boost may have a positive impact on athletic performance.
In 2021, the International Society of Sports Nutrition (ISSN) conducted a research review to determine how caffeine affects exercise. They concluded that caffeine consistently improves athletic performance, including:
- aerobic endurance
- muscular endurance
- Movement speed
- muscle strength
- Performance in sprinting, jumping and throwing
Research also shows that caffeine consistently improves athletic performance, particularly in aerobic conditioning. The effects of caffeine depend on individual response, dose and activity performed, but positive performance effects have been shown in certain activities in both elite and recreational athletes. Habitual caffeine intake may also inhibit performance-enhancing responses.
It’s worth noting that adequate sleep and balanced nutrition also aid athletic performance, so it’s equally important to make sure the caffeine you consume doesn’t disrupt your sleep. Food and nutrition tracking tools like MyFitnessPal can help you learn more about how factors like food choices impact your performance.
Caffeine and exercise: getting the timing and dose right
The key to using caffeine to enhance exercise is to consume the right amount at the right time.
According to the ISSN report, consuming caffeine about 60 minutes before exercise is the most commonly used time to replenish caffeine. This estimate is based on research showing that the effects of caffeine tend to peak around 60 minutes after drinking.
ISSN also stated in the same report that the optimal dose of caffeine for improving performance is 3-6 mg of caffeine per kilogram of body weight. Some people may benefit from doses as low as 2 mg per kilogram of body weight.
This means that a person weighing 150 pounds may benefit from 137 mg to 408 mg of caffeine. This is equivalent to 10 ounces to 35 ounces of coffee.
The ISSN report also noted that higher doses (eg, 9 mg per kilogram of body weight) were associated with higher rates of side effects.
Sources of Caffeine and Types of Caffeine You May Consider Before Exercise
Most people drink caffeinated drinks for energy. These sources of caffeine are usually easy to find and easy to consume. But if those aren’t your thing, there are several options with different caffeine levels.
The FDA estimates that an 8-ounce cup of tea contains 30 to 50 milligrams and an 8-ounce cup of coffee contains 80 to 100 milligrams. Caffeinated energy drinks may contain 40-250 mg per 8 fluid ounces.
You can also buy over-the-counter caffeine pills before exercise. Another option is gum with added caffeine. Depending on the brand, each piece of gum may contain 80 to 300 mg. If you don’t want to fill your stomach with fluid before exercise, gum and pills may be a good option.
bottom line
Caffeine can be part of a healthy lifestyle. Caffeine, when consumed in moderation, is safe for most people and can improve athletic performance by increasing energy levels, endurance and strength. But moderation is key: Too much caffeine can make you jittery, while caffeine too late in the day can make it harder to fall asleep.
MyFitnessPal’s tracking tools help you track your sleep, diet, and exercise. Taken together, this information can help you make choices to achieve your diet and exercise goals. Start using the MyFitnessPal app today!
Originally published July 11, 2019; updated August 9, 2024
