How Much Caffeine Is in Pre-Workout? (And How Much Is Too Much, According to a Nutrition Coach)

You’ve seen it, or maybe even felt it. The sluggishness before a workout—then, the chugging of a pre-workout drink that seems to give an athlete superpowers. Or, at least, a jolt of seemingly superpowered energy.

With that kind of kick, it’s no wonder that pre-workout is the second highest-selling dietary supplement in the United States (coming in second only to multivitamins). (1) But what exactly does this powerful stimulant do to your body? And how much caffeine is in pre-workout, anyway?

Key Takeaways

• Pre-workout contains the same amount of caffeine as three cups of coffee, between 150-300 milligrams (mg).
• The caffeine in pre-workout works to delay fatigue and increase adrenaline, making you more energized and able to perform better in your workout. 
• Consuming over 400 mg of caffeine per day can cause increases in heart rate and blood pressure.

What Pre-Workout Supplements Do

• Delays Fatigue: Caffeine, the primary ingredient in most pre-workouts, stimulates your central nervous system (CNS) by blocking adenosine, a neurotransmitter that signals to your body that it’s tired. (2) This process makes you feel awake, energized, and ready to tackle your workout. 
• Boosts Energy Levels: Caffeine increases adrenaline, giving you an energy boost. The adrenaline tells your body to save its glycogen stores and instead burn fat for energy. By saving glycogen, your muscles have more energy for longer. (2) B vitamins, also found in many pre-workouts, play a role in producing energy as they assist in converting carbohydrates, fats, and proteins into energy. (3)
• Maximizes Focus: Because caffeine makes you feel more awake, it helps you stay focused and alert. (2) Plus, tyrosine—an amino acid found in many pre-workouts—also helps with cognitive function and concentration. (1) Both provide a sharp focus, allowing you to stay present to get the most out of your workout.
• Increases Endurance: Beta-alanine, another common ingredient in pre-workout, extends your endurance by giving you more energy and lengthening the amount of time you can work before needing to rest. (4) This means you may be able to squeeze a couple more reps out of your lifts or shorten your mile time.
• May Increase Strength: Caffeine releases dopamine, which lowers your perceptions of pain. As a result, your RPE (rating of perceived exertion) may be lower, which could mean lifting heavier weights or more reps before your body reaches its limit. (5)(6)(7) This may also aid muscle growth as a secondary side effect. 
• May Improve Power Output: Caffeine increases the availability of calcium in muscle cells, which assists in stronger, more forceful muscle contractions. This may result in greater muscle strength and power output, which is particularly beneficial in activities like weightlifting or sprinting that require short bursts of intense effort. (2)(8)
• Gives You A “Pump”: L-arginine and L-citrulline, found in most pre-workouts, increase nitric oxide production in your body. This dilates the blood vessels and improves blood flow, especially to the muscles, resulting in them appearing large and full—that’s the much-desired “pump” that many lifters chase. (1)(9)
• Assists in Recovery: BCAAs (branched-chain amino acids) are a key ingredient in many pre-workouts that provide essential amino acids your muscles use during exercise. They help reduce muscle breakdown and speed up recovery. (10)
• Tingling Sensation: Beta-alanine causes the tingling, itchy feeling under your skin you experience after taking some pre-workouts. High doses of beta-alanine in particular can trigger the prickling sensation. It’s harmless and tends to subside as the body adjusts to the excess beta-alanine in its system. (11)

[Read More: The Best Pre-Workouts for Men]

How Much Caffeine Should Pre-Workout Have?

• The Food and Drug Administration (FDA) suggests that healthy adults should not consume more than 400 mg of caffeine per day, which is the equivalent of about four or five cups of coffee. (12)
• The International Society of Sports Nutrition (ISSN) says that three to six milligrams of caffeine per kilogram of body weight has been shown to improve athletic performance. (2)
• The amount of caffeine in an eight-ounce cup of coffee is about 80 to 100 mg. (12)
• Most pre-workout products have a caffeine content ranging from 150 mg to 300 mg per serving, which equates to about two or three cups of coffee. (13) 
• The ISSN states consuming more than 400 mg of caffeine or nine milligrams per kilogram of body weight could give you negative side effects like headaches, insomnia, nervousness, anxiety, irritability, elevated blood pressure, frequent urination, rapid or irregular heartbeat, or muscle tremors. (2)
• If you drink coffee, then you shouldn’t consume more than one to two cups of coffee on days you also take pre-workout, depending on the amount of caffeine in your pre-workout.
• If you don’t drink coffee or other caffeinated beverages, you can get away with a pre-workout containing a higher dose of caffeine. 
• Typically, it can take four to six hours for your body to metabolize half of the caffeine you consumed. (12) If you consume a pre-workout in the morning before your workout, five hours later, you will still have half the amount of caffeine in your body from the pre-workout. 
• If you have anxiety or any heart conditions, you may be more sensitive to caffeine. In this case, some of our favorite non-stim pre-workouts might benefit you more.
• If you are pregnant, doctors recommend not exceeding 200 mg per day. (14)

Side Effects of Caffeine

The main “side effect” of caffeine is the one most people pour their cup of Joe (or pre-workout, as it were) for—that sweet, exhaustion-fighting energy boost. But that’s not all the good stuff does.

It Increases Your Heart Rate

A healthy dose of caffeine (100-200 mg) can get your blood flowing and increase your heart rate, getting you excited and ready to work out.

But it’s not all cheery all the time. High doses (between 300 to 400 mg) can cause significant increases in heart rate and blood pressure, possibly leading to heart palpitations. (2)

It Can Improve Physical Performance

Caffeine is a stimulant that gives you a boost of energy and makes you more alert. This energy and adrenaline boost helps you perform better in both strength training and cardio workouts. A recent study found that participants who took pre-workout were able to run 12.5 percent faster than those who took a placebo. (15) 

[Read More: Coffee vs. Pre-Workout: Which Should You Use Before Your Workouts?]

The ISSN-recommended dose of caffeine as an ergogenic aid is three to six milligrams per kilogram of body weight. (2) They also caution that anything over nine milligrams per kilogram of body weight can cause negative side effects without further benefiting your workouts. 

It Can Shorten Reaction Time

When caffeine blocks your adenosine receptors, it can make you alert and increase cognitive function. This allows you to process quickly and react faster to stimuli. (16)

A recent study found that 32 to 300 mg of caffeine for someone at 75 kilos (about 165 pounds) boosted cognitive function and reaction time. (1) Anything more tends to cause the opposite effect. 

It Can Induce Anxiety 

In high doses, caffeine can cause anxiety, jitters, and difficulty focusing. These side effects depend on your tolerance to caffeine. Some find that they can have four or five cups before feelings of anxiety arise, but others are more sensitive. (2) In some severe cases, consuming too much caffeine can cause panic attacks. (17)(18)

It Can Boost Your Metabolism

Caffeine stimulates the central nervous system, leading to an increase in heat production, known as thermogenesis. This means your body burns more calories to produce this heat, even at rest. A 2020 study found that ingesting 100 to 140 mg of caffeine can give you a quick metabolism boost for generally 30 to 60 minutes after ingestion. (19) 

It Can Lift Your Mood

Because caffeine releases dopamine, it can make you feel happier. In some cases, it can even help ease symptoms of depression. (2) On the flip side, some studies have shown that consuming too much caffeine (more than nine milligrams per kilogram of body weight) can have the opposite effect, causing anxiety. (2)(17)(18)

It Can Interrupt Your Sleep Cycle

If you consume caffeine too close to going to sleep, you may have trouble falling asleep, a reduction in sleep quality, or even insomnia. (2) Typically it takes one and a half to nine hours for your body to metabolize caffeine. (20) It varies for each individual, so it’s important to listen to your body over time to learn how caffeine will affect your sleep cycle.

In general, the half-life of caffeine is about five hours in healthy adults, meaning that if you drink one cup of coffee (about 100 mg of caffeine), you will still have 50 mg in your system five hours later and five hours after that there will be 25 mg of caffeine in your system. (20) Knowing how long it takes for caffeine to leave your body is imperative for ensuring it doesn’t interrupt your sleep cycle. 

It May Cause Stomach and Digestive Issues

Caffeine is acidic, so consuming too much can lead to a build-up of acid in your stomach which can cause stomach pain or irritation from a build-up of acid in the stomach and possibly even cause ulcers. (21) This is especially common when consuming caffeine on an empty stomach.

[Read More: The Effects of Creatine and Caffeine When Taken Together]

Excessive amounts of caffeine can also cause digestive issues because it speeds up the contractions in the muscles in the digestive tract, which can lead to stomach cramps and an overall upset stomach. (21)

It May Impact Addiction and Your Tolerance 

The chemical reaction that caffeine has in your brain is addictive. Your body gets used to the increased levels of dopamine, adrenaline, and cortisol, and like any drug, you can experience withdrawal when you go without it. Withdrawal symptoms include headaches, fatigue, irritability, and difficulty concentrating. (22)

[Read More: How Much Caffeine Do You Need to Get Your Best Workout? (Brought to You by Kaged Muscle)]

As you continue to consume caffeine, you also become less sensitive to its effects. As you build up a tolerance to caffeine, you may find you need more to feel the same benefits. (22)

FAQs

Here are some of the questions we hear most often about caffeine and pre-workout.

Editor’s Note: The content on BarBend is meant to be informative in nature, but it should not be taken as medical advice. When starting a new training regimen and/or diet, it is always a good idea to consult with a trusted medical professional. We are not a medical resource. The opinions and articles on this site are not intended for use as diagnosis, prevention, and/or treatment of health problems. They are not substitutes for consulting a qualified medical professional.

Resources

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2. Guest NS, VanDusseldorp TA, Nelson MT, Grgic J, Schoenfeld BJ, Jenkins NDM, Arent SM, Antonio J, Stout JR, Trexler ET, Smith-Ryan AE, Goldstein ER, Kalman DS, Campbell BI. International Society of Sports Nutrition position stand: caffeine and exercise performance. J Int Soc Sports Nutr. 2021 Jan 2;18(1):1.
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