Many people drink coffee before a workout for its caffeine boost. While it may enhance physical performance and improve brain function, drinking coffee pre-workout is not for everyone.

The above information comes from the journal Nutrients in a 2018 review of studies looking at caffeine and exercise.

Caffeine affects people differently, and it can have negative side effects — such as anxiety, insomnia, and upset stomach.

People who are sensitive to caffeine may prefer a caffeine-free snack or beverage before a workout. Others may choose to avoid food or drinks before a workout to prevent a stomachache.

Read more to learn about the benefits of drinking coffee before a workout, caffeine-related side effects, and caffeine-free pre-workout alternatives.

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Most people who drink coffee before a workout consume it for its caffeine, a natural stimulant. Numerous studies suggest that consuming caffeine pre-workout may:

  • enhance a person’s physical performance
  • boost their cognitive function
  • potentially increase the amount of fat they burn

Enhanced physical performance

Researchers have studied how caffeine can enhance a person’s physical performance during exercise. In particular, they observed how it affects muscle strength, endurance, and cardiovascular abilities.

One 2018 systematic review of multiple studies found that even moderate doses of pre-performance caffeine could enhance individual athletic performance.

Another systematic review looked at caffeine’s effect depending on the duration of a workout or athletic event. The researchers found that it may be particularly useful in enhancing the performance of endurance athletes.

Some research indicates caffeine may improve muscle performance, but it is not clear why or how much. One 2017 study showed a small improvement in lower leg power.

Additionally, a small study of Spanish Jiu-Jitsu athletes found that consuming 3 milligrams (mg) of caffeine per kilogram (kg) of body weight before a workout increased their one and two leg vertical jump height.

One 2019 review noted that many of these studies looked at young people, men, and athletes. The authors say more research is needed in women, older adults, and non-athletes.

Improved cognitive function

Many people drink coffee to feel more awake or alert. However, an improvement in cognitive function may also mean an improvement in physical performance.

A 2018 review investigated this by looking at the influence of caffeine on physical and cognitive performance. It indicated that caffeine may improve cognitive states associated with better athletic performance, such as:

  • alertness
  • concentration
  • energy levels
  • fatigue

Potential increase in fat oxidation

Some research suggests that consuming caffeine before exercising may be linked to an increase in fat oxidation (or “fat burning”). However, this is still unclear.

While some people think the increased fat oxidation is responsible for the performance-enhancing effects of caffeine, the International Society of Sports Nutrition (ISSN) disagrees. Its 2021 review on caffeine and exercise performance points out that although caffeine may increase fat oxidation, it is not necessarily linked to a person’s athletic performance.

Additionally, it states that the amount of caffeine consumed matters for the fat oxidation effect. Lower doses may have a lesser effect than higher doses.

The best time to drink pre-workout coffee depends on the person’s goals.

For example, if a person wants to increase physical performance, including muscle endurance and strength, the ISSN says people should consume caffeine 60 minutes before exercising.

One study conducted in healthy males looked at how caffeine timing affected performance in different types of exercises. It showed that consuming caffeine 1 hour before exercise improved explosive vertical jumps and isometric muscle contractions.

An isometric exercise is a static exercise that does not involve joint motion. Examples of these exercises include planks, wall-sits, and static squats.

However, consuming caffeine 30 minutes before exercise improved isokinetic performance. Isokinetic exercises are dynamic, and while the resistance may vary, the speed stays the same. Isokinetic exercises include pushups and pullups.

According to the ISSN, the amount of caffeine that has consistently shown enhanced exercise performance is a dose of 3–6 mg per kg of body mass.

High doses (9 mg per kg) may cause side effects unnecessary for performance enhancement, such as upset stomach and insomnia. Research on smaller doses of caffeine is limited, but one study indicates that they can improve alertness with fewer side effects than higher doses.

Many people enjoy consuming coffee for its taste. However, individuals looking for the performance benefits of caffeine can consume it in any form. Popular choices are:

Be aware that some products, such as pre-workout drinks and candies, may contain large amounts of sugar in addition to caffeine.

Although caffeine can improve athletic performance, there are potential negative risks and side effects to consider.

Upset stomach

One of the most common issues is an upset stomach. Drinking coffee on an empty stomach or consuming food or beverages too close to exercising can cause stomachache.

To avoid this, a person may choose to work out on an empty stomach, wait longer between drinking coffee and working out, or consume less liquid.

They can also try drinking a smaller quantity of stronger coffee. For example, one espresso is 2 fluid ounces (oz). It has less liquid volume but more caffeine (roughly 130 mg) than regular brewed black coffee, which provides around 95 mg of caffeine per 8 fluid oz.

Insomnia and anxiety

For various reasons, some people are more sensitive to caffeine than others. Consuming large amounts of caffeine may cause negative side effects such as sleep problems and anxiety.

Insomnia, in particular, may work against people hoping to use caffeine for improved athletic performance, because a lack of sleep hinders muscle recovery.

More serious, but less common, risks are also associated with caffeine.

Caffeine overdose

Although uncommon, it is possible for someone to experience caffeine toxicity, or caffeine overdose, if they consume too much caffeine.

Overdosing on caffeine is very rare, and it is usually a result of accidentally consuming too much in the form of supplements or energy drinks. People should be sure to read the labels of products with caffeine to make sure they are not overconsuming them.

Caffeine is not for everyone, but it is not the only pre-workout option for people looking to optimize their workouts.

Some people who are sensitive to the effects of caffeine prefer pre-workout snacks and beverages that can boost their energy, focus, and alertness.

One simple way of achieving this is by consuming a carbohydrate-rich snack before exercising. Drinking a fruit juice or smoothie can provide the energy a person needs to exercise.

Learn more about what pre-workout snacks to try.

Certain products contain potentially beneficial ingredients, such as theacrine, beta-alanine, and arginine silicate. These ingredients increase blood flow and claim to produce more noticeable post-workout muscle swelling.

Research on these ingredients and products suggests varying levels of effectiveness.

For example, during a 2019 study involving 12 resistance-trained males, researchers compared TeaCrine (the branded version of theacrine) and 300 mg of caffeine. They found that the caffeine improved focus, energy, and motivation, while TeaCrine did not. However, it is important to note that these findings were self-reported by the participants.

After reviewing the literature on beta-alanine, the ISSN concluded the supplement can combat fatigue and improve exercise performance.

People should always be careful when purchasing and consuming supplements, as these products are not regulated as tightly as pharmaceuticals. They should contact a doctor or pharmacist if they have any concerns.

Because caffeine can enhance physical performance and cognitive function, it is a popular pre-workout beverage.

Although research has shown it can improve athletic performance, especially in endurance athletes, be aware of the risks of caffeine. For example, it can cause insomnia, jitters, and stomachache.