Whether you’re waking up early to hit the gym before work or heading to an evening exercise class, you may turn to a caffeinated drink for extra energy before you work out.
It makes sense. Coffee, tea, caffeinated sodas, and energy drinks are all popular choices for giving your body a little extra energy. But are they really a good idea before a workout?
Some studies have shown that a little caffeine can improve some aspects of athletic performance, but too much caffeine can have drawbacks. The key is knowing how much caffeine is right for you and when to take it.
Caffeine consumption: exploring 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 the body processes adenosine. Adenosine is a chemical that helps regulate energy and sleep. It builds up in the brain throughout the day and, when it binds to its receptors, causes fatigue.
Caffeine has a similar structure to adenosine, so it can fit into the same receptors that adenosine uses. When caffeine binds to adenosine receptors, it stops adenosine from attaching to them. This means that adenosine can’t do its job of making you feel sleepy. As a result, you feel more awake and alert.
These receptors exist in cells throughout the body, so caffeine affects more than just the brain. Caffeine triggers a number of different physical and neurological responses, including:
- Central nervous system stimulation: Caffeine crosses the blood-brain barrier and directly stimulates the brain. Because of this, caffeine can make you feel more awake and energetic.
- Diuretic effects: Caffeine increases urination.
- Digestive Functions: Coffee stimulates the release of stomach acid. Some research indicates that drinking caffeinated beverages, such as coffee, tea, and soda, may increase the likelihood of heartburn and upset stomach.
Caffeine is a highly effective stimulant. When caffeine is consumed, 100% of the caffeine is absorbed. Peak blood levels are reached 30 to 45 minutes after ingestion, and peak plasma concentrations are reached 15 to 120 minutes after ingestion. Caffeine has a half-life in the body of approximately four to six hours, suggesting that traces of caffeine are likely still present in the bloodstream 12 hours or more later.
As with most substances, caffeine carries the risk of negative effects, especially if the FDA recommendation of less than 400 mg per day is exceeded.
The most common side effects are mild and include anxiety, restlessness, insomnia, increased urination, muscle spasms or tremors, irregular heart rate, and gastrointestinal irritation. More serious side effects may include cardiac arrhythmia, myocardial infarction, and electrolyte disturbances.
Caffeine can be an effective stimulant, so it’s tempting to reach for a coffee or tea before a workout. But before you chug an iced latte or a highly caffeinated energy drink, you should consider how it might affect your body.
What are the disadvantages of caffeine before training?
The effects of caffeine on different parts of the body can have unexpected effects on your training. This can be especially true if you don’t yet know how your body reacts to caffeine.
For one, caffeine can stimulate bowel movements. The exact reason for the need to go to the bathroom after coffee is not fully understood, but some research suggests that caffeine increases hormones that trigger colon contractions.
If this is common for you, you should consider bathroom access when planning your caffeine intake and training program. For example, drinking caffeine before a trail run can leave you in an uncomfortable situation when nature calls. Caffeine’s diuretic effects can also contribute to dehydration after an intense workout.
Caffeine can also cause insomnia. The effects of caffeine can take anywhere from 2-12 hours to wear off, so drinking a coffee in the afternoon may mean you’re still experiencing the effects of coffee at bedtime. Experts suggest you should stop consuming caffeine at least eight hours before you go to sleep. So, if you plan to hit the gym after work, avoid caffeine.
Consuming caffeine when you are not used to it can cause unpleasant side effects such as increased anxiety and blood pressure, which could negatively affect your training.
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What are the benefits of caffeine before training?
It can be beneficial to consume caffeine before you hit the gym. After all, it is a stimulant, so it can make you feel more energetic. That extra energy boost can have positive effects 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 shows an improvement in athletic performance, including:
- Aerobic resistance
- Muscular endurance
- Movement speed
- Muscle strength
- Performance in sprints, jumps and throws.
Research also shows that caffeine consistently leads to increased exercise performance, particularly in aerobic conditioning. The effect of caffeine depends on the individual response, dose, and activity performed, but it has shown positive results on performance in both elite and recreational athletes in certain activities. Habitual caffeine consumption may also reduce the performance-enhancing response.
It’s worth noting that getting enough sleep and eating a balanced diet also support athletic performance, so it’s equally important to make sure caffeine consumption doesn’t interfere with sleep. Food and nutrition tracking tools, such as MyFitnessPal, allow you to gain more insight into how factors such as your food choices can affect your athletic performance.
Caffeine and exercise: take it at the right time and dose
The key to using caffeine to enhance workouts is to consume the right amount at the right time.
According to the ISSN report, the most common time to take a caffeine supplement is to consume caffeine about 60 minutes before exercise. This estimate is based on research showing that the effects of caffeine tend to peak about 60 minutes after consumption.
The ISSN also notes in the same report that the optimal dose of caffeine for performance enhancement is 3 to 6 mg of caffeine per kilogram of body mass. Some people may benefit from a dose as low as 2 mg per kilogram of body mass.
This means that a 150-pound person could benefit from between 137 mg and 408 mg of caffeine, which is equivalent to between 10 oz and 35 oz of coffee.
The ISSN report also notes that higher doses, such as 9 mg per kilogram of body mass, are associated with a higher incidence of side effects.
Caffeine sources and types to consider before training
Most people turn to caffeinated beverages for an extra boost. These sources of caffeine are usually easy to find and consume. But if you don’t like them, there are a variety of options with different caffeine contents.
The FDA estimates that an 8-ounce cup of tea contains between 30 and 50 milligrams, and an 8-ounce cup of coffee has between 80 and 100 milligrams. Caffeinated energy drinks can contain between 40 and 250 mg per 8 fluid ounces.
You can also find caffeine pills over the counter before you exercise. Another option is to chew gum with added caffeine. Depending on the brand, these can contain anywhere from 80 to 300 mg per gum. Gum and pills can be a good option if you don’t want to fill your stomach with liquid before you exercise.
The final result
Caffeine can be part of a healthy lifestyle. Moderate caffeine consumption is safe for most people and can improve energy levels, endurance and strength, which can lead to better athletic performance. But the key is moderation: too much caffeine can make you feel jittery, and if you consume it too late in the day, it can make it difficult to sleep.
MyFitnessPal’s tracking tools can help you track your sleep, nutrition, and workouts. Together, that information can help you make decisions that help you reach your diet and exercise goals. Get started with the MyFitnessPal app today!
Originally published July 11, 2019; updated August 9, 2024
