Dec 19, 2023
Caffeine, Pre-workout, and Energy Drinks – The Good, the Bad, the Ugly

Hanny Podgurski, MS, RD

Written by a Collegiate and Professional Sports Dietitians Association Registered Dietitian (RD). To learn more about sports nutrition and CPSDA, go to

Student-athletes balance training, lifts, class schedules, and a social life. Long days can leave them feeling drained and turning to some form of caffeine for extra energy. About 96% of caffeine consumption from beverages comes from coffee, soft drinks, and tea.2 Energy drink consumption, pre-workouts, or other supplements containing caffeine are also popular.2 Caffeine temporarily binds the receptors of a chemical in your brain (adenosine) that is one regulator of sleep, and tricks you into thinking you have energy or “fake energy”. However, food is the true physiological source of energy; more specifically, carbohydrates are the body’s main energy source. For athletes to have optimal energy, it is important they are consuming enough carbohydrates for their rigorous training schedules, which is often a challenge.

Caffeine has been researched for improving exercise performance and has shown positive effects when dosed properly. It has consistently been shown to improve exercise performance when consumed in a dose of 3 to 6 mg/kg body mass, though there is much individual variation on if someone responds or not.2 Here are a couple of representative studies pointing out these effects.

In one5, resistance-trained males took a 300mg caffeine gel with 88g carbohydrate (roughly 3.6mg/kg caffeine), or just the carbohydrate placebo. In the caffeine condition, there was a relative increase of 2.9% and 3.3% in vertical jump tests, 3%-6.9% in lower body strength tests, and 3.5%-12% in bench press barbell velocity.

On the endurance side, another study with recreationally trained males saw a 3.2% relative increase in total work performed during a total 90-minute cycling trial when taking 6mg/kg caffeine6. Not everyone responded to the caffeine, with a range in performance change of -0.4 to 7.7%.

Very high doses, (9mg/kg body mass) are associated with a high incidence of side effects.2 To put the 3-6mg/kg into perspective, if you had an athlete who weighs 150lbs (68kg) that would be about 200mg- 400mg of caffeine, which equals about two to four 8oz cups of coffee. The optimal timing is 60 minutes before the point of fatigue.

Pre-workout dietary supplements are used to help increase alertness and performance during workouts. They typically contain a blend of ingredients such as caffeine, branched-chain amino acids, nitrates, creatine, and beta-alanine. The range of caffeine content in pre-workout tends to be between 150mg to 300mg, assuming the product is quality tested and the label is accurate. If athletes are consuming other caffeine-containing beverages during the day and also using pre-workout, they could be consuming up to 500mg to 700mg of caffeine a day. Big questions to ask in these situations though are why the athlete is relying on so much caffeine, and what quality nutrition is it replacing? Seeing or hearing about excess caffeine use is a great opportunity to try to shift into other intentional behaviors with sleep, recovery, and nutrition.

The NCAA bans multiple substances that pose a risk to athletes, with stimulants being part of that list. Since caffeine is a stimulant, athletes are at risk of failing a drug test if consumed in too high of quantities. Per the NCAA, a urinary caffeine concentration exceeding 15 micrograms per milliliter or consuming 500mg of caffeine 2 to 3 hours before competition can result in a positive drug test.1 Energy drinks have grown in popularity over the years and are often marketed toward fit and active individuals, making them appealing to athletes. Many contain guarana seed extract and/or green tea extract, which are caffeine sources. If consumed frequently and in high enough quantities, these products can potentially disqualify students from competition, resulting in a year of lost eligibility. No foods or beverages containing caffeine are required to list caffeine content on their labels. Only over-the-counter drugs must list caffeine content. Additionally, the amount of caffeine in energy drinks can vary and the actual caffeine content might not be easily identified.3

Supplements are not well regulated by the FDA, posing a risk of them being contaminated with banned substances not listed in the ingredients. Many reports have been published about athletes who took over-the-counter supplements, only to find out later that the product was contaminated with a substance banned by their sport or organization.4 Doing research before taking a supplement is ideal. Tips for safety in supplement decisions include; choosing third-party tested certified products (NSF for Sport or Informed Sport), which give an extra layer of assessment of the product’s safety; and talking to a Sports Dietitian who is qualified to give their expert opinion on a supplement to make sure it is safe, effective and legal to take.

It is important to educate ourselves and athletes about the good and the bad of caffeine consumption. If an athlete approaches you asking about caffeine, energy drinks or any supplements make sure you are providing them with the right information. You can refer them to speak with their Sports Dietitian, let them know the risks of not taking third-party tested supplements, the risk of overconsuming caffeine with potentially a lost year of eligibility, and that no food and beverages that contain caffeine are required to list caffeine content on their labels.


  1. Caffeine and Athletic Performance . CPSDA |Collegiate & Professional Sports Dietitians Association. (n.d.).
  2. Guest, N. S., VanDusseldorp, T. A., Nelson, M. T., Grgic, J., Schoenfeld, B. J., Jenkins, N. D., Arent, S. M., Antonio, J., Stout, J. R., Trexler, E. T., Smith-Ryan, A. E., Goldstein, E. R., Kalman, D. S., & Campbell, B. I. (2021). International Society of Sports Nutrition Position Stand: Caffeine and Exercise Performance. Journal of the International Society of Sports Nutrition, 18(1).
  3. U.S. Department of Health and Human Services. (n.d.). Energy drinks. National Center for Complementary and Integrative Health.,these%20visits%20resulted%20in%20hospitalization.
  4. Use of supplements by student athletes: Certified for sport®. Use of Supplements by Student Athletes | Certified for Sport®. (n.d.).
  5. Venier, S., Grgic, J., & Mikulic, P. (2019). Caffeinated Gel Ingestion Enhances Jump Performance, Muscle Strength, and Power in Trained Men. Nutrients, 11(4), 937.
  6. Beaumont, R. E., & James, L. J. (2017). Effect of a moderate caffeine dose on endurance cycle performance and thermoregulation during prolonged exercise in the heat. Journal of science and medicine in sport, 20(11), 1024–1028.



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