Pre-Workout Supplements: What’s In Them & Do They Actually Work?

By Jereme’ Gallier, RD, LD

The dietary supplement industry is a multi-billion-dollar market that targets the emotions and quick-fix mindsets of people all around the world. It is not uncommon for people to buy into the hoax that one magic pill or powder can transform a person from an average Joe/Jane to a god in the gym. Though some products can be trusted, many people begin taking a supplement without verifying the actual safety or effectiveness of what they are ingesting.

Pre-workout supplements, commonly referred to as “pre-workouts,” are among the most popular ergogenic aids (a substance or technique that promotes athletic performance) and are specifically marketed in the manner previously mentioned. Most of the pre-workouts on the market have similar ingredients with varying dosages. The most common ingredients found in pre-workout supplements include caffeine, creatine, 𝛃-alanine (beta-alanine), and nitric oxide promoters such as citrulline, beetroot juice, and pomegranate extract. On product labels, companies claim that these ingredients can improve strength, reaction time, focus, and endurance. (Kaczka et al., 2020) However, most people, including athletes, do not fully understand the purpose of each ingredient and are unfamiliar with  appropriate dosing, potential side effects, and quality assurance of these pre-workout products. The content that follows provides evidence-based descriptions of the ingredients most commonly found in pre-workout supplements, as well as the research on multi-ingredient products, and considerations to take when advising athletes on safe and effective use of these supplements .

Caffeine

Caffeine is a well-known and frequently consumed psychoactive substance typically used to increase mental alertness and decrease level of perceived exertion. (Guest et al., 2021) Some natural sources of caffeine include coffee, tea, cocoa, and yerba mate. As an ergogenic aid, caffeine has been shown to improve endurance exercise performance, muscular endurance, strength, and power in trained and untrained individuals. (Guest et al., 2021) Sport-specific research on the benefits of caffeine show that team sport athletes such as those playing basketball, soccer, volleyball, rugby, and field hockey found improvements in decision-making and increased endurance during high-intensity activity. (Guest et al., 2021) Additionally, researchers discovered increased offensive activity and endurance in combat sports. (Felippe et al., 2016)  One study also noted faster completion of a set distance in cross-country skiing. (Stadheim et al., 2013) The average caffeine dose to elicit a positive result ranges from 3-6 mg/kg body mass, 30 to 90 minutes prior to activity. (Guest et al., 2021) Side effects such as increased heart rate, sleep disturbances, gastrointestinal distress, and anxiety may occur in association with an increase in the amount and timing of caffeine consumed. (Pallares et al., 2013; Campo et al, 2019; Spriet, 2014) Additionally, caffeine is labeled as a banned substance by the National Collegiate Athletic Association, requiring that urinary caffeine concentration not exceed 15 µg/m (NCAA). In addition, caffeine is monitored by the World Anti-Doping Agency (WADA), which recommends limiting caffeine urine concentration to 12 µg/ml l. It should be noted that to attain these urinary concentrations would require an oral intake over three times the effective mg/kg dose within the hours before drug testing. (Spriet, 2014; NCAA.org, 2021; WADA.org, 2022)

Creatine

Creatine supplementation is one of the most popular and well-studied ergogenic aids in sport performance literature. In the human body, creatine fuels energy production for short, intense muscle contractions. (Kreider et. al, 2017) Creatine stores in the body are maintained by production in the liver and kidneys as well as through intake of dietary creatine sources. (Kreider et. al, 2017) Food sources of creatine are all animal-derived and include meat, fish, and milk. (Cleveland Clinic, 2020) One of the most notable benefits of creatine supplementation is increased phosphocreatine availability for acute, explosive exercise to promote muscle and strength gains. Additional benefits include reduced injury risk and improved cognitive performance in stressed situations such as sleep deprivation. Novel research also suggests creatine supplementation may assist in reducing the severity of or enhancing recovery from mild traumatic brain injuries. (Cooke et al., 2009; Kreider et al., 2017; Kreider et al; 2021) Experts recommend two different ways of dosing creatine for performance effects. The first involves a loading phase of about 0.3 g/kg body weight per day for five to seven days followed by a maintenance phase of 3-5 g/day. (Krieder et al., 2017)  The second method, which takes longer to maximize creatine stores but may be more favorable if gut distress is an issue, skips the loading phase and goes straight into taking 3-5 g/day over a three-to-four-week cycle. (Krieder et al., 2017) Due to creatine’s mechanism of action, supplementation may benefit power and strength athletes such as throwers and gymnasts, and athletes in sports that require intermittent sprints with recovery such as American football, basketball, soccer, and tennis. (Krieder, 2003) Additionally, creatine supplementation has been shown to elicit performance benefits for those following a vegan and vegetarian diet who are physically active. (Kavani et. al, 2020) At recommended doses, creatine poses no known safety risk to trained or untrained athletes regardless of age. (Kreider et al, 2017) However, for those under the age of 18, appropriate supervision to ensure proper dosing and consumption of a well-balanced diet is recommended. (Jagim et. al, 2018) Creatine is not banned by the NCAA or WADA, but is classified as an impermissible substance, which is a product an athlete can use legally, but the athletic department cannot provide it and it must be purchased separately by the athlete. (Link & Clark, 2020; NCAA.org, 2021; WADA.org, 2022)

Beta-alanine

Beta-alanine is an amino acid produced by the liver and found in poultry, red meat, and fish. (Trexler et al., 2015; Sports Dietitians Australia, 2015) It is the rate-limiting component in the production of carnosine, which acts as a defense against acid accumulation in the muscle during exercise. (Harris et al., 2006) The resulting decrease in acid accumulation can enhance performance by delaying the onset of fatigue within the working muscle leading to a prolonged ability to perform in the sport or exercise. Supplementation of beta-alanine has been shown to favorably impact carnosine levels in human skeletal muscle. (Hoffman et al., 2018) Current literature states that endurance sports involving relatively short distances will benefit most from supplementation of beta-alanine. (Brisola & Zagatto, 2019) Sports with the strongest evidence include cycling races of 4 kilometers, rowing races of 2000 meters, combat sports, water polo, and 100- and 200-meter swimming events. (Brisola & Zagatto, 2019) In order to produce these benefits, it is recommended to supplement with 4-6 g of beta-alanine daily, split into doses of 2g or less for at least two to four weeks. (Trexler et al., 2015) Supplementation with beta-alanine at the recommended doses has been deemed relatively safe in healthy populations; however, skin tingling (clinically referred to as paresthesia) is a side effect that may occur. (Harris et al., 2006) If skin tingling does occur, it is recommended to divide the doses into 1.6 g at a time throughout the day. (Trexler et al., 2015) Many people may mistake this skin tingling to mean that the supplement they are taking contains an effective dose; however, many products containing beta-alanine are multi-ingredient products that do not contain the effective dosage per serving, meaning an individual would need additional beta-alanine on top of what is provided in the multi-ingredient product. Beta-alanine is not banned by WADA or the NCAA, but would be classified as an impermissible substance by the NCAA. (NCAA.org, 2021; WADA.org, 2022)

Nitric Oxide Promoters

Nitric oxide (NO) is a gaseous signaling molecule mostly known for improving oxygen and energy substrate delivery to active muscles via increased vasodilation. (Joyner et al., 2015) Other effects include improved glucose uptake and decreased muscle fatigue. (Bailey et al., 2011)

Citrulline

Previously, the amino acid L-arginine, a direct precursor to NO, was thought to be the best supplement to improve vasodilation through increasing NO levels in the body; however, current research has shown that the amino acid citrulline is superior for enhancing L-arginine levels due to greater absorption, thus producing greater NO levels in the body. (Trexler et al., 2019) As a result, citrulline is a secondary precursor to NO that elicits a greater increase in NO production compared to L-arginine. (Trexler et al., 2019) Watermelon is the most abundant natural source of citrulline followed by casaba-type melon, mouse melon, and horned melon; however, it would not be feasible to consume enough watermelon in one sitting to produce the effects previously noted. (Hartman et al., 2019) Current research supports that citrulline supplementation primarily benefits elite strength and power athletes where the slightest edge will determine success.  (Trexler et al., 2019) Citrulline is available in two forms, citrulline malate & L-citrulline. Both are effective, but their dosing differs. Most studies reported favorable results with supplementation of 8 g of citrulline malate 60 minutes prior to training while L-citrulline studies report 3 g to be an effective dose with the same timing. (Guisado et al. 2010; Trexler et al., 2019) Research suggests supplementation with citrulline is generally safe; however, gastrointestinal discomfort has been reported in 15% of citrulline malate users. (Guisado et al., 2010) Citrulline is not banned by WADA or the NCAA, but would be classified as an impermissible substance by the NCAA. (NCAA.org, 2021; WADA.org, 2022)

Beetroot Juice

Beetroot juice (BRJ) has been growing in popularity among athletes due to its high nitrate (NO3) concentration, which can be converted to NO in the body. In trained male athletes, short term use of BRJ has been shown to improve time to exhaustion, maximal rowing repetitions, high intermittent exercise capacity as well as decrease oxygen utilization. (Zamani et al., 2021) Research regarding acute use of beetroot juice in trained men has not yet produced conclusive results on benefits. (Zamani et al., 2021) Although there have not been many studies for acute or short term use in trained women, Peeling et al found that acute supplementation of BRJ in female kayak athletes has a positive effect on time trial performances. (Peeling et al., 2015) Based on current literature, it seems that endurance athletes will benefit most from supplementation of BRJ. Appropriate dosing for BRJ involves ingesting a dose of 400-500mg of nitrates in the form of beetroot powder mixed with water or concentrated BRJ 150 minutes prior to activity. (Dominguez et al., 2017) Athletes should also avoid using mouthwash around the time they ingest BRJ because this prevents the conversion of NO3 to NO due to the mouthwash destroying the bacteria involved in the reduction of  NO3 to produce NO in the stomach. (Dominguez et al., 2017) BRJ is not banned by WADA or the NCAA. (NCAA.org, 2021; WADA.org, 2022)

Pomegranate Extract

Pomegranate extract (POMe) is derived from the pomegranate fruit and is available in a liquid and dry powder form. (Seeram, 2008) Each form possesses polyphenols, the bioactive compounds that assist with reducing oxidative species that could harm the body. Additionally, polyphenols promote formation of NO through limiting oxidative species’ interaction with NO. (Ignarro, 2006) Research has shown multiple benefits related to supplementation of POMe including increased time-to-exhaustion, improved maximal load lifted and muscle strength recovery, reduced acute and delayed muscle soreness and fatigue post-exercise, and alleviation of muscle damage following intense resistance training. (Ammar et al., 2018) Studies reported positive results with intake of 1000mg of POMe powder or ingestion of 750 ml of pomegranate juice confirmed to contain at least 0.7g polyphenol/0.5 L juice. (Ammar et al., 2018) To benefit from the recovery aspects, athletes need to supplement recommended POMe doses within 48h post-exercise. To elicit the strength and time-to-exhaustion benefits of POMe, it is recommended that athletes supplement 1h prior to activity. (Ammar et al., 2018) Acute and short term use of POMe has been shown to be relatively safe. However, researchers note that further research is needed to determine if long term use may blunt physiological adaptations related to training. (Ammar et al., 2018) POMe is not banned by WADA or the NCAA. (NCAA.org, 2021; WADA.org, 2022)

Multi-Ingredient Pre-Workout Research

The information discussed up to this point has focused on research that studied the effects of individual ingredients. However, many pre-workout supplements include multiple ingredients with varying amounts of each ingredient. Researchers have suggested that the combination of these ingredients may lead to boosted activity compared to supplementing with the single ingredients alone; however, there is a scarcity of literature on this topic due to most multi-ingredient pre-workout supplements (MIPS) not having discrete label information regarding amounts of individual ingredients, but instead listing “proprietary” blends. (Harty et al., 2018) Currently, the majority of studies involving MIPS have been focused on acute use (one-time) and long-term use (>10 days). Research has shown that acute use of MIPS resulted in force and power production being sustained longer throughout training bouts as well as increased total training volume compared to placebo. Long-term use of MIPS have shown improved maximal force production in addition to a reduction of fat mass or increase in lean mass compared to placebo. Studies involving short-term use (<10 days) are scarce and have yet to elicit promising results in any aspect. (Harty et al., 2018; Kaczka et al., 2020; Tinsley et al., 2017)  Given that MIPS vary in the ingredients and dosing of individual ingredients they contain, one would need to utilize the information provided in prior sections to assess which pre-workout supplements may be most effective, depending on product contents.  Regarding timing of ingestion, studies range from 10-60 minutes prior to workouts. (Harty et al., 2018; Kaczka et al., 2020; Tinsley et al., 2017) Of those studied, multi-ingredient pre-workout supplements have been shown to be safe for acute use and chronic use up to 8 weeks. However, further research is needed to determine safety for long-term use.

Safety and Efficacy Considerations

Athletes should be aware of pre-workout supplements containing proprietary blends and banned substances. Proprietary blends, as mentioned previously,  are those which do not state how much of each ingredient a product contains, meaning the product could have excessively high amounts of the ingredients or amounts so low that it will not produce the desired results. (Harty et al., 2018, Wang, 2019) Banned substances are those that governing bodies have determined illegal for athletes to consume. To determine whether a product is banned substance free, one should refer to third party organizations trusted by sports dietitians such as NSF Certified for Sport, Informed Sport, and the Banned Substance Control Group (BSCG). These organizations conduct unbiased third-party testing of sports supplements to determine if their contents are free of banned substances. Additionally, NSF Certified for Sport tests products to ensure that they contain the ingredients stated on the label, and that the reported dose per serving is accurate. NSF Certified for Sport and Informed Sport each offer a free app listing tested products as well as a barcode scanner that can be used to scan products in real time to verify or deny certification. Lastly, although this article provides information about the supplements discussed, it is always best for athletes to discuss supplement use with a registered sports dietitian to identify which supplemental nutrients may be beneficial for their particular sport and safe given the context of its use, as some supplements could cause adverse effects if taken with certain medications or in the presence of some medical conditions.


References


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This article was written by a Collegiate and Professional Sports Dietitian Association Registered Dietitian (RD).  To learn more about sports nutrition and CPSDA, go to www.sportsrd.org