What Does Pre-Workout Do? (You’ll Be Surprised)

December 17, 2021

What does pre-workout even do? For many, it’s a mystical experience of increased alertness, concentration, and being ready to take anything head-on.

Pre-workout improves athletic performance and mental function so you can get more out of your workout. This could be more endurance, strength, or a better ability to concentrate.

But there’s more to it than this. What pre-workout does depend on the ingredients in the formulation. So, I will break down the most common ingredients first.

What Does Pre-Workout Do?

Pre-workouts enhance athletic performance through unique blends of ingredients. These ingredients can increase strength, endurance, and even pumps when lifting weights.

Here is a list of common active ingredients you can expect within a pre-workout supplement and what they do.

Caffeine – Caffeine is the most common stimulant used within pre-workouts, for a good reason. It has been shown to improve power, speed, endurance, and the number of reps performed at a given weight [1,2].

The typical performance-enhancing dose ranges between 3-6 mg per kilogram of body weight. Still, those who are not caffeine habituated will benefit from smaller doses.

Taurine – Taurine allows smaller doses of caffeine to have a performance-enhancing effect. For example, 71-3105 mg reduced the need for higher caffeine doses with more taurine equalling better performance [3].

L-Citrulline/Citrulline Malate – Citrulline Malate is an “endurance” ingredient that improves your number of reps performed to failure, reduces muscle soreness 24 and 48 hours after working out, and increases endurance time to exhaustion [4,5,6].

BCAA – BCAAs are proteins thought to enhance strength and muscle growth more than other amino acids. However, recent research has shown BCAAs have no benefits on strength and muscle growth, and as long as you have adequate daily protein, you don’t need them [7].

Beta-Alanine – Beta-Alanine enhances short exercise performance at high intensities. That is, extending how long you can sustain an intensity within the 1-4-minute range [8,9]. Ideally, this is taken daily to reap the benefits. However, larger acute doses can have a performance-enhancing benefit. This is the ingredient that makes you tingle and itch.

Betaine Anhydrous – Betaine has similar mechanisms to Citrulline Malate. It can increase the number of reps performed and reduce the rise in blood lactate with exercise [10].

Creatine Monohydrate – While a common pre-workout ingredient, I don’t think it should be. Creatine has no acute benefit to performance and needs to be taken daily to see benefits. When taken chronically, you can expect increases in strength and perform more reps [11]. If you take it separately, you can mix creatine with pre-workout.

L-Theanine – L-Theanine pairs nicely with caffeine. They work synergistically to reduce stress, anxiety, reaction time, tiredness and increase alertness [12,13]. This is what is known as a brain drug or nootropic. It’s about enhancing the performance of your mind along with the physical.

What Is The Main Purpose Of Pre-Workout?

What Is The Main Purpose Of Pre-Workout

The primary purpose of a pre-workout is to enhance athletic performance and mental clarity. Whether that is increasing strength, the number of reps performed in a set, endurance, or getting a better pump, these are all areas where pre-workout can benefit you.

Does Pre-Workout Make You Gain Weight?

Pre-workout does not make you gain weight. Weight gain is a function of caloric intake, where consuming more calories than you use will result in the scale moving up. The number of calories per serving in a pre-workout is usually well under 100 calories. This is not likely to cause weight gain.

Further, pre-workout can help you go harder, faster, and longer. You will likely burn more calories during your workout, negating the calories you ingested.

Does Pre-Workout Help Build Muscle?

Pre-workout does help build muscle. But not how you may think. The ingredients within the pre-workout don’t lead to more significant muscle growth. But the typical pre-workout ingredients help you perform more volume in the gym with heavier weights.

Overall, this maximizes the muscle growth response since volume, time under tension, and the amount of tension created by the muscle heavily influence hypertrophy. The one ingredient that may help build muscle is betaine anhydrous as it downregulates the AMPK pathway. Since this pathway inhibits the muscle-building mTOR pathway, it may allow you to stay anabolic for longer.

Can You Take Pre-Workout On An Empty Stomach?

Can You Take Pre-Workout On An Empty Stomach

You can take pre-workout on an empty stomach. But this will be on an individual basis. Many may find that caffeine and other stimulants will give you jitters and a racing heart rate. I find caffeine on an empty stomach does this to me.

Further, some may find pre-workout upsets their stomach if it is empty. I would advise you to eat a meal before taking your pre-workout regardless. One, it’s going to protect against any of these things happening to you. And two, you’re going to be fueled for your workout, so you don’t fade away after 45 minutes.

Is BCAA Pre-Workout?

While branch chain amino acids (BCAA) are sometimes in pre-workouts, they are not pre-workouts because they don’t enhance athletic performance. They are added to pre-workout because of the belief that specific amino acids can improve the building of new proteins (new muscle).

However, recent research has concluded that over the long term, as long as daily protein requirements are met, then additional BCAA supplementation is unnecessary and does not lead to any more significant muscle gain [7].

Also, if you eat meat or take a protein shake after working out, you’re getting BCAAs within those foods.

Should You Take Pre-Workout Before Cardio?

Should You Take Pre-Workout Before Cardio

You can take pre-workout before cardio. Some pre-workouts are formulated specifically for endurance exercise. Regardless, most pre-workouts, even if formulated for the gym, will benefit your cardio training by attenuating the rise in blood lactate and increasing the size of your blood vessels.

What To Do If You Take Too Much Pre-Workout?

If you take too much pre-workout, the first thing to remember is to control your breath. Slowly breathing in and out can help control your heart rate. Secondly, have something to eat. It may slow down the digestion of the pre-workout ingredients. Thirdly, you can take L-Theanine, which will counteract the jittery effect of too much caffeine.

Finally, you’ll have to ride it out. You can’t stop the jitters and heart-pounding on the spot. If you feel things are getting worse, head to the emergency room.


Pre-workout has unique benefits for exercise that can enhance your performance. As the industry progresses, more pre-workouts are utilizing the benefits of brain enhancement, so you are getting physical improvement and mental benefits.


1. Astorino, T. A., & Roberson, D. W. (2010). Efficacy of acute caffeine ingestion for short-term high-intensity exercise performance: a systematic review. The Journal of Strength & Conditioning Research, 24(1), 257-265.

2. Southward, K., Rutherfurd-Markwick, K. J., & Ali, A. (2018). The effect of acute caffeine ingestion on endurance performance: a systematic review and meta-analysis. Sports Medicine, 48(8), 1913-1928.

3. Souza, D. B., Del Coso, J., Casonatto, J., & Polito, M. D. (2017). Acute effects of caffeine-containing energy drinks on physical performance: a systematic review and meta-analysis. European journal of nutrition56(1), 13-27.

4. Gonzalez, A. M., & Trexler, E. T. (2020). Effects of citrulline supplementation on exercise performance in humans: A review of the current literature. The Journal of Strength & Conditioning Research, 34(5), 1480-1495.

5. Bailey, S. J., Blackwell, J. R., Lord, T., Vanhatalo, A., Winyard, P. G., & Jones, A. M. (2015). l-Citrulline supplementation improves O2 uptake kinetics and high-intensity exercise performance in humans. Journal of Applied Physiology.

6. Suzuki, T., Morita, M., Kobayashi, Y., & Kamimura, A. (2016). Oral L-citrulline supplementation enhances cycling time trial performance in healthy trained men: Double-blind randomized placebo-controlled 2-way crossover study. Journal of the International Society of Sports Nutrition, 13(1), 1-8.

7. Plotkin, D. L., Delcastillo, K., Van Every, D. W., Tipton, K. D., Aragon, A. A., & Schoenfeld, B. J. (2021). Isolated Leucine and Branched-Chain Amino Acid Supplementation for Enhancing Muscular Strength and Hypertrophy: A Narrative Review. International journal of sport nutrition and exercise metabolism31(3), 292-301.

8. Hobson, R. M., Saunders, B., Ball, G., Harris, R. C., & Sale, C. (2012). Effects of β-alanine supplementation on exercise performance: a meta-analysis. Amino acids, 43(1), 25-37.

9. Saunders, B., Elliott-Sale, K., Artioli, G. G., Swinton, P. A., Dolan, E., Roschel, H., … & Gualano, B. (2017). β-alanine supplementation to improve exercise capacity and performance: a systematic review and meta-analysis. British Journal of Sports Medicine, 51(8), 658-669.

10. Trepanowski, J. F., Farney, T. M., McCarthy, C. G., Schilling, B. K., Craig, S. A., & Bloomer, R. J. (2011). The effects of chronic betaine supplementation on exercise performance, skeletal muscle oxygen saturation and associated biochemical parameters in resistance-trained men. The Journal of Strength & Conditioning Research25(12), 3461-3471.

11. Rawson, E. S., & Volek, J. S. (2003). Effects of creatine supplementation and resistance training on muscle strength and weightlifting performance. The Journal of Strength & Conditioning Research17(4), 822-831.

12. Lu, K., Gray, M. A., Oliver, C., Liley, D. T., Harrison, B. J., Bartholomeusz, C. F., … & Nathan, P. J. (2004). The acute effects of L‐theanine in comparison with alprazolam on anticipatory anxiety in humans. Human Psychopharmacology: Clinical and Experimental, 19(7), 457-465

13. Haskell, C. F., Kennedy, D. O., Milne, A. L., Wesnes, K. A., & Scholey, A. B. (2008). The effects of L-theanine, caffeine and their combination on cognition and mood. Biological psychology77(2), 113-122.

About the Author

I am a professional strength & conditioning coach that works with professional and international teams and athletes. I am a published scientific researcher and have completed my Masters in Sport & Exercise Science. I've combined my knowledge of research and experience to bring you the most practical bites to be applied to your training.

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