Pre-workout

Pre-workout is a generic term for a range of bodybuilding supplement products used by athletes and weightlifters to enhance athletic performance. ^[1] Supplements are taken to increase endurance, energy, and focus during a workout. ^[1] Pre-workout supplements contain a variety of ingredients such as caffeine and creatine, differing by capsule or powder products. ^{[2] [3]} The first pre-workout product entered the market in 1982, and since then the category has grown in use. ^[4] Some pre-workout products contain ingredients linked to adverse effects. ^[2] Although these products are not regulated, the Food and Drug Administration (FDA) warns consumers to be cautious when consuming them. ^[5]

History

In 1982, Dan Duchaine formulated the first pre-workout, called Ultimate Orange, in Venice, California. Ultimate Orange was commonly used among bodybuilders. ^[4]

Between the late 1990s and early 2000s, consumers alleged that an active ingredient in Ultimate Orange, called Ephedra, caused high blood pressure, strokes, seizures, cardiac arrhythmia, and heart attacks. ^[2]

The risk of using Ephedra gave rise to creatine. ^[6] Creatine is a supplement that was used by a lot of athletes in the 1992 Olympics where it gained most of its popularity from.

Creatine was considered a form of pre-workout in the late 1990s until the early 2000s where it was then later used with a mixture of other supplements. ^[7] Creatine was negatively received when it was first introduced to the public until the last decade where it is now one of the most used supplements. ^[8]

In the early 2000s, supplement companies created more potent forms of pre-workout that caused the blood flow in muscles to increase temporarily, giving lifters a better “pump." ^[2] These more potent supplements are called Arginine AKG, Arginine Malate, and Citrulline. ^[2]

In 2005, chemist Patrick Arnold formulated a pre-workout which contained a new ingredient called DMAA (dimethylamylamine). ^[9] The product Jack3d gained notoriety for its potency, but its high concentrations of DMAA were suspected of causing shortness of breath, chest pain, and an elevated risk of heart attacks. ^[2] Jack3d was banned in 2012 by the FDA. ^[2]

Ingredients

Pre-workout supplements are available in different forms, including tablets, capsules, liquids, powders, and bars. ^[10] A number of common ingredients are used. There is considerable overlap between the ingredients used in pre-workout blends and other supplements intended for weight loss, improving mood, life extension, or as purported nootropics or aphrodisiacs, although certain ingredients tend to be found only in products intended to assist in bodybuilding or athletic training. Some ingredients such as caffeine, creatine and β-alanine are found in nearly all pre-workout blends, but each branded product is a "proprietary blend" with an average of 18 different ingredients, the exact composition and proportions of which can vary widely between different products. ^{[11] [12]}

• Ephedrine (usually as Ephedra extract) was a common ingredient in many pre-workout supplements in the 1990s and early 2000s, sometimes in combination with caffeine and aspirin (the so-called ECA stack), however, following many reports of serious side effects and some deaths, it was banned for use in supplements by the FDA in 2004 throughout the USA, and many other countries have enacted similar bans.
• Caffeine is now one of the most common ingredients, found in one study to be in 86% of the bestselling pre-workout supplements. ^[3] Caffeine works with the central nervous system to increase the blood flow. ^[13] Caffeine is a popular ingredient in pre-workout because it increases alertness, mental concentration, and energy. ^[14] Related compounds such as theophylline or theobromine (sometimes as "cocoa extract") may also be used. ^[15]
• Methylhexanamine, also known as DMAA, is another stimulant which was widely used for some time as an alternative or supplement to caffeine. ^[16] DMAA can increase alertness in the body and help burn body fat. ^[17] The FDA has warned that DMAA "is known to narrow the blood vessels and arteries, which can elevate blood pressure and may lead to cardiovascular events ranging from shortness of breath and tightening in the chest to heart attack". DMAA is also considered a prohibited stimulant by the United States Anti-Doping Agency. ^[18] Following the widespread banning of DMAA, it has in some cases been replaced by similar compounds such as DMBA, octodrine, tuaminoheptane or DEPEA, which are associated with similar side effects. ^[19]
• Carbohydrates are usually present, often in a mix of simple sugars like glucose and more complex oligosaccharides such as maltodextrin which are supposed to provide more sustained energy. Carbohydrates cause an increase in serotonin levels. ^[20] These are used both to provide a sweet taste and fuel for exercise, though evidence for whether they actually enhance exercise performance is mixed. ^{[21] [22]}
• Protein supplements, usually in a palatable powdered form such as whey protein or rice protein, are also commonly used both for flavour and as a fuel for muscle growth and recovery. ^{[23] [24]}
• Electrolytes providing sodium, potassium and magnesium (and often others such as zinc, calcium, iron etc in smaller amounts) are often included to replace those lost due to sweating during heavy exercise, generally as a mixture of different salts, sometimes including exotic forms such as zinc monomethionine aspartate or calcium fructoborate which are supposed to be better absorbed or have other special properties. Electrolytes help the body perform homeostasis and prevent dehydration.
• Nitrate salts are commonly included (often as "beetroot extract") for their supposed benefits for endurance exercise. Sometimes this is achieved by using nitrate salts of other ingredients (e.g. arginine nitrate, creatine nitrate). ^[25]
• Creatine, a natural chemical created in the kidneys and liver, is used supposedly to improve physical performance. ^{[26] [27]} It also promotes an increase in muscle growth. ^[28]
• β-Alanine is a common ingredient found in 87% of leading pre-workout formulas. Beta-alanine decreases fatigue during high-intensity exercise by increasing the muscle carnosine concentration. ^[29]
• Branched-chain amino acids, leucine, isoleucine and valine are commonly used for their muscle fueling properties and relief of post-workout soreness, often alongside other amino acids such as glutamine which are thought to have synergistic effects. Results from research have been mixed, and the dose contained in commercial pre-workout products is often less than an optimum effective dose. ^{[30] [31] [32]}
• β-Hydroxy-β-methylbutyrate may sometimes be used as an ingredient in some products, ^{[33] [34]} though is prohibitively expensive for most commercial pre-workout blends.
• Arginine (sometimes as complexes like arginine alpha-ketoglutarate), is also commonly used as a nitric oxide precursor and supposed booster of growth hormone and IGF-1 release, though studies have shown limited benefits, and generally at higher doses than are present in typical pre-workout products. ^{[35] [36]}
• Ornithine or L-ornithine L-aspartate are sometimes used as an alternative or in addition to arginine, and have generally similar properties. ^[37]
• Citrulline (sometimes as "watermelon extract") is used as an alternative or supplement to arginine, and is claimed to reduce post-exercise soreness. ^[38]
• Agmatine is also often used as an alternative or supplement to arginine. ^[39]
• Taurine is also a common ingredient in pre-workout, and can be used as a supplement taken alone. It is similar to creatine purportedly to aid muscle hypertrophy that increases strength, endurance, reduced muscle damage, and helps with a faster recovery. ^{[40] [41]}
• Tyrosine or its precursor N-acetyl-L-tyrosine are commonly used to purportedly boost levels of dopamine and noradrenaline. ^[42] Some brands may contain L-dopa (generally as Mucuna pruriens extract), ^[43] but this is classified as a prescription medicine in many countries.
• Theanine is often used as an ingredient (sometimes as "green tea extract", though this may alternatively be used to refer to EGCG, which may also be present), to supposedly improve mental and physical performance, and reduce anxiety. ^{[44] [45]}
• Piperine (often as "black pepper extract") is often included possibly to improve absorption of other ingredients, and for its supposed ability to improve muscle recovery. ^{[46] [47]}
• B vitamins are another common ingredient, most commonly vitamin B₃ and vitamin B₁₂ in various forms, but also often thiamine (sometimes as sulbutiamine), ^[48] pantothenic acid (vitamin B₅) and folic acid.
• Carnitine or its precursor acetylcarnitine are sometimes added to the mix for their supposed ability to enhance exercise performance and aid recovery, though evidence for these benefits is weak. ^{[49] [50]}
• Betaine (trimethylglycine) is often used as an ingredient, despite limited evidence for effectiveness in increasing athletic performance. ^{[51] [52]}
• Phenethylamines such as β-phenethylamine, β-methylphenethylamine, deterenol, halostachine, N-methyltyramine, hordenine, or synephrine (sometimes as "bitter orange extract") may be included as thermogenics to aid in weight loss. ^[53]
• Higenamine (norcoclaurine) is also often added for its supposed weight loss and mild stimulant properties. ^[54]
• Resveratrol and related polyphenols (usually as "grape seed extract") are often included. ^[55]
• Yohimbine has also been used as an ingredient (often as Pausinystalia johimbe extract), as a supposed testosterone booster and fat-loss agent, ^{[56] [57] [58]} but it has been associated with dangerous side effects, and is also a prescription medicine in many countries. ^[59]
• Phenylpiracetam is also sometimes used as an ingredient for its nootropic and stimulant effects. ^[60]
• Capsaicin is sometimes used as an ingredient in gelcap pre-workout formulations, both as a supoosed weight loss aid and for improvement of endurance. ^[61]
• Plant extracts, such as Ginkgo biloba , Panax ginseng , Rhodiola rosea and Huperzine A (from Huperzia serrata ), are sometimes included for their supposed ability to improve endurance and mental clarity, despite limited evidence for efficacy.
• Ecdysteroids, such as ecdysterone and turkesterone, ^[62] and other plant derived steroid like compounds such as 5α-Hydroxylaxogenin are sometimes used as ingredients, despite inconclusive results as to their supposed anabolic effects. ^[63]
• Prohormones such as DHEA, CDMA, 1-androstenediol and 7α-methyl-19-norandrostenedione were widely used in pre-workout formulations prior to 2014 when they were formally banned. These compounds are not anabolic agents in their own right, but are metabolised into anabolic steroids of a type which at the time were not restricted. Despite most known prohormones having now been banned, novel compounds of this type or older compounds which are simply not listed as ingredients, are still sometimes found in over-the-counter pre-workout products, and are a frequent cause of inadvertent drug testing failures by athletes in competition. ^[64]
• Selective androgen receptor modulators (SARMs) such as enobosarm and ligandrol are also sometimes found as ingredients in pre-workout supplement blends, and again when present are often not accurately declared on the ingredients listing. ^[65]

Retail supplements

Pre-workout supplements are sold in a variety of retailers. The top-selling brands of pre-workout supplements in 2019 included Pre JYM Pre Workout by JYM Supplemental Science, ENGN Shred Pre Workout by EVLUTION Nutrition, and C4 Original Pre Workout by Cellucor. ^[1] These brands were the top three in the overall bestseller category on leading bodybuilding informational website bodybuilding.com and Sports Illustrated. ^{[1] [66]} Some variations on common pre-workout products include sugar-free, creatine-free and stimulant-free options. The market size for pre-workout products was a $2.7 billion industry in 2008. ^[67] In 2022 the market size for pre-workout had grown to $14.2 billion. ^[68]

Lack of regulation can mean that the ingredients used to prepare the product may not be of high quality and purity. This can mean the dose stated on the ingredients does not match the actual composition of the blend. Plant extracts in particular are often adulterated or of varying quality, but may be assumed by manufacturers to be pure and consistent. Also, protein powders used to prepare the blend may sometimes be contaminated with melamine, a plastic precursor which is sometimes added to produce false positive results for nitrogen content. Up to 50% of pre-workout blends analysed in one study were found to be contaminated with melamine. ^{[69] [70]}

Purported benefits

Impact on muscles

An increase in muscle endurance is primarily attributed to the large amounts of caffeine in pre-workout supplements. ^{[71] [72] [73]} The ingested caffeine acts as an adenosine receptor antagonist, which serves to reduce overall pain experienced by the consumer and allowing them to work for longer periods of time. ^[72] Pre-workout also increases the amount of carbohydrates in the body which are used to increase energy in the body. ^[74]

Pre-workout has shown to decrease the time it takes for muscles to recover from intense exercise, allowing athletes to reduce time between training sessions. The improvement in muscle recovery is associated with the branched chain amino acids (BCAAs) found in pre-workout, ^[75] particularly, glutamine. ^[76]

Other Benefits

Pre-workout has shown to make athletes feel more energetic during exercise, but the higher energy levels are based on subjective judgement and there is little quantitative proof of an increase in energy. ^[77] Caffeine's role in enhancing the improvement in perceived energy is observed through the large amounts of caffeine typically found in pre-workout supplements. ^[78] Caffeine also increases calcium release which allows for stronger muscle contractions during high intensity workouts. ^[79]

Studies also show that the caffeine in pre-workout improves focus and alertness in athletes as observed through a decrease in reaction-time in different settings. ^{[80] [77]}

Adverse effects

Various adverse effects may occur according to the pre-workout product and dose of supplement consumed. ^[10] Some potential side effects of taking pre-workout could include nausea and skin irritation. ^[81] Other adverse effects have been shown to arise when the product contains ingredients such as synephrine and caffeine. Synephrine is often used as a weight loss supplement and commonly found in pre-workout. Synephrine has been found to cause heart problems and other cardiovascular issues. ^[82] Caffeine is also a common ingredient found in pre-workout which may cause an increase in blood pressure. Another issue that may arise is a higher risk in cardiac and liver related diseases due to the high concentration of caffeine in these types of products. ^[83]

Food and Drug Administration

The FDA has minimal control when regulating dietary supplements like pre-workout. Product manufacturers are responsible to verify that dietary supplements are safe for consumption. ^[84] Financial limitations prevent the FDA from testing dietary supplements before they enter the marketplace. ^[84] Once a supplement is available for sale, the FDA is responsible to document and monitor manufacturer reports of adverse effects. ^[5] Manufacturers are obligated to report documented adverse effects to the FDA. ^[5]

The FDA recommends speaking with a healthcare professional before using dietary supplements. Ingredients in pre-workout can have negative side effects or contraindications with other medications. ^[5] Taking dietary supplements may have life-threatening consequences if taken with pre-existing health conditions. ^[5] Federal laws state that a supplement does not have to be declared safe by FDA standards when labeled. ^[5] Most supplement businesses hire third-party companies to identify the contents of their supplement to ensure it enhances athletic performance. This also aids in assuring that a product’s labeled ingredients are free from illegal substances. ^[10]

See also

• Doping in sport
• Patent medicine

References

1. "Best Pre-Workout Supplements - 2019 Top 10 List". Bodybuilding.com. Retrieved 2020-04-03.
2. Heffernan C (2017-04-10). "A History of Pre-Workout Supplements". Physical Culture Study. Retrieved 2020-04-03.
3. Jagim AR, Harty PS, Camic CL (January 2019). "Common Ingredient Profiles of Multi-Ingredient Pre-Workout Supplements". Nutrients. 11 (2): 254. doi: 10.3390/nu11020254 . PMC   6413194 . PMID   30678328.
4. Gugliotta G (2000-07-23). "Ephedra Lawsuits Show Big Increase". Washington Post. ISSN   0190-8286 . Retrieved 2020-04-03.
5. Office of the Commissioner (2019-02-09). "FDA 101: Dietary Supplements". FDA.
6. Dodge, Jennah R.; Ford, M. Allison; Perko, Michael A. (May 2003). "From Ephedra to Creatine: Using Theory to Respond to Dietary Supplement Use in Young Athletes". American Journal of Health Studies. 18 (2/3): 111–116.
7. Heffernan C (2017-04-10). "A History of Pre-Workout Supplements". Physical Culture Study. Retrieved 2020-04-03.
8. Heffernan, Conor (2018-11-21). "The Untold History of Workout Supplements". BarBend. Retrieved 2023-09-29.
9. "jack3d". Physical Culture Study. 2017-04-10. Retrieved 2020-04-03.
10. Office of Dietary Supplements. "Dietary Supplements for Exercise and Athletic Performance". ods.od.nih.gov. Retrieved 2019-03-20.
11. Harty PS, Zabriskie HA, Erickson JL, Molling PE, Kerksick CM, Jagim AR (August 2018). "Multi-ingredient pre-workout supplements, safety implications, and performance outcomes: a brief review". Journal of the International Society of Sports Nutrition. 15 (1): 41. doi: 10.1186/s12970-018-0247-6 . PMC   6083567 . PMID   30089501.
12. Jagim AR, Harty PS, Camic CL (January 2019). "Common Ingredient Profiles of Multi-Ingredient Pre-Workout Supplements". Nutrients. 11 (2): 254. doi: 10.3390/nu11020254 . PMC   6413194 . PMID   30678328.
13. Glade, Michael J. (2010-10-01). "Caffeine—Not just a stimulant" . Nutrition. 26 (10): 932–938. doi:10.1016/j.nut.2010.08.004. ISSN   0899-9007. PMID   20888549.
14. "Caffeine". medlineplus.gov. Retrieved 2020-04-03.
15. Kennedy M (November 2020). "Effects of Theophylline and Theobromine on exercise performance and implications for competition sport: A systematic review". Drug Testing and Analysis. 13 (1): 36–43. doi:10.1002/dta.2970. PMID   33188564. S2CID   226947746.
16. Center for Food Safety and Applied Nutrition (2020-02-04). "DMAA in Products Marketed as Dietary Supplements". FDA. Archived from the original on August 28, 2019.
17. "Gale - Product Login". galeapps.gale.com. Retrieved 2023-10-04.
18. "Athlete Advisory - Methylhexaneamine And Dietary Supplements". U.S. Anti-Doping Agency (USADA). 2011-06-16. Retrieved 2020-04-03.
19. Cohen PA, Travis JC, Keizers PH, Deuster P, Venhuis BJ (2018). "Four experimental stimulants found in sports and weight loss supplements: 2-amino-6-methylheptane (octodrine), 1,4-dimethylamylamine (1,4-DMAA), 1,3-dimethylamylamine (1,3-DMAA) and 1,3-dimethylbutylamine (1,3-DMBA)". Clinical Toxicology. 56 (6): 421–426. doi:10.1080/15563650.2017.1398328. PMID   29115866. S2CID   5193271.
20. Mantantzis, Konstantinos; Schlaghecken, Friederike; Sünram-Lea, Sandra I.; Maylor, Elizabeth A. (2019-06-01). "Sugar rush or sugar crash? A meta-analysis of carbohydrate effects on mood". Neuroscience & Biobehavioral Reviews. 101: 45–67. doi:10.1016/j.neubiorev.2019.03.016. ISSN   0149-7634. PMID   30951762. S2CID   92575160.
21. Outlaw JJ, Wilborn CD, Smith-Ryan AE, Hayward SE, Urbina SL, Taylor LW, Foster CA (2014). "Effects of a pre-and post-workout protein-carbohydrate supplement in trained crossfit individuals". SpringerPlus. 3: 369. doi: 10.1186/2193-1801-3-369 . PMC   4125607 . PMID   25110627.
22. Maroufi K, Razavi R, Gaeini AA, Nourshahi M (December 2020). "The effects of acute consumption of carbohydrate-protein supplement in varied ratios on CrossFit athletes' performance in two CrossFit exercises: a randomized cross-over trial". The Journal of Sports Medicine and Physical Fitness. 61 (10): 1362–1368. doi:10.23736/S0022-4707.20.11774-2. ISSN   0022-4707. PMID   33314886. S2CID   229179829.
23. Davies RW, Carson BP, Jakeman PM (February 2018). "The Effect of Whey Protein Supplementation on the Temporal Recovery of Muscle Function Following Resistance Training: A Systematic Review and Meta-Analysis". Nutrients. 10 (2): 221. doi: 10.3390/nu10020221 . PMC   5852797 . PMID   29462923.
24. Gala K, Desai V, Liu N, Omer EM, McClave SA (December 2020). "How to Increase Muscle Mass in Critically Ill Patients: Lessons Learned from Athletes and Bodybuilders". Current Nutrition Reports. 9 (4): 369–380. doi:10.1007/s13668-020-00334-0. PMID   33098051. S2CID   225049327.
25. McMahon NF, Leveritt MD, Pavey TG (April 2017). "The Effect of Dietary Nitrate Supplementation on Endurance Exercise Performance in Healthy Adults: A Systematic Review and Meta-Analysis". Sports Medicine. 47 (4): 735–756. doi:10.1007/s40279-016-0617-7. PMID   27600147. S2CID   207494150.
26. Cooper R, Naclerio F, Allgrove J, Jimenez A (July 2012). "Creatine supplementation with specific view to exercise/sports performance: an update". Journal of the International Society of Sports Nutrition. 9 (1): 33. doi: 10.1186/1550-2783-9-33 . PMC   3407788 . PMID   22817979.
27. Butts J, Jacobs B, Silvis M (2018). "Creatine Use in Sports". Sports Health. 10 (1): 31–34. doi:10.1177/1941738117737248. PMC   5753968 . PMID   29059531.
28. Poortmans, Jacques R.; Francaux, Marc (2000). "Adverse Effects of Creatine Supplementation: Fact or Fiction?" . Sports Medicine. 30 (3): 155–170. doi:10.2165/00007256-200030030-00002. ISSN   0112-1642. PMID   10999421. S2CID   25617337.
29. Hobson RM, Saunders B, Ball G, Harris RC, Sale C (July 2012). "Effects of β-alanine supplementation on exercise performance: a meta-analysis". Amino Acids. 43 (1): 25–37. doi:10.1007/s00726-011-1200-z. PMC   3374095 . PMID   22270875.
30. Santos CS, Nascimento FE (September 2019). "Isolated branched-chain amino acid intake and muscle protein synthesis in humans: a biochemical review". Einstein. 17 (3): eRB4898. doi: 10.31744/einstein_journal/2019RB4898 . PMC   6718193 . PMID   31508659.
31. Fedewa MV, Spencer SO, Williams TD, Becker ZE, Fuqua CA (November 2019). "Effect of branched-Chain Amino Acid Supplementation on Muscle Soreness following Exercise: A Meta-Analysis". International Journal for Vitamin and Nutrition Research. 89 (5–6): 348–356. doi:10.1024/0300-9831/a000543. PMID   30938579. S2CID   91189309.
32. Holeček M (August 2020). "Branched-Chain Amino Acids and Branched-Chain Keto Acids in Hyperammonemic States: Metabolism and as Supplements". Metabolites. 10 (8): 324. doi: 10.3390/metabo10080324 . PMC   7464849 . PMID   32784821.
33. Silva VR, Belozo FL, Micheletti TO, Conrado M, Stout JR, Pimentel GD, Gonzalez AM (September 2017). "β-hydroxy-β-methylbutyrate free acid supplementation may improve recovery and muscle adaptations after resistance training: a systematic review". Nutrition Research. 45: 1–9. doi:10.1016/j.nutres.2017.07.008. hdl: 11449/170023 . PMID   29037326.
34. Kim J, Kim EK (June 2020). "Nutritional Strategies to Optimize Performanceand Recovery in Rowing Athletes". Nutrients. 12 (6): 1685. doi: 10.3390/nu12061685 . PMC   7352678 . PMID   32516908.
35. da Silva DV, Conte-Junior CA, Paschoalin VM, da Silveira Alvares T (2014). "Hormonal response to L-arginine supplementation in physically active individuals". Food & Nutrition Research. 58: 22569. doi: 10.3402/fnr.v58.22569 . PMC   3967014 . PMID   24678288.
36. Viribay A, Burgos J, Fernández-Landa J, Seco-Calvo J, Mielgo-Ayuso J (May 2020). "Effects of Arginine Supplementation on Athletic Performance Based on Energy Metabolism: A Systematic Review and Meta-Analysis". Nutrients. 12 (5): 1300. doi: 10.3390/nu12051300 . PMC   7282262 . PMID   32370176.
37. Mikulski T, Dabrowski J, Hilgier W, Ziemba A, Krzeminski K (2015). "Effects of supplementation with branched chain amino acids and ornithine aspartate on plasma ammonia and central fatigue during exercise in healthy men". Folia Neuropathologica. 53 (4): 377–86. doi: 10.5114/fn.2015.56552 . PMID   26785372.
38. Rhim HC, Kim SJ, Park J, Jang KM (December 2020). "Effect of citrulline on post-exercise rating of perceived exertion, muscle soreness, and blood lactate levels: A systematic review and meta-analysis". Journal of Sport and Health Science. 9 (6): 553–561. doi: 10.1016/j.jshs.2020.02.003 . PMC   7749242 . PMID   33308806.
39. Laube G, Bernstein HG (July 2017). "Agmatine: multifunctional arginine metabolite and magic bullet in clinical neuroscience?". The Biochemical Journal. 474 (15): 2619–2640. doi: 10.1042/BCJ20170007 . PMID   28747403.
40. Eudy AE, Gordon LL, Hockaday BC, Lee DA, Lee V, Luu D, et al. (April 2013). "Efficacy and safety of ingredients found in preworkout supplements". American Journal of Health-System Pharmacy. 70 (7): 577–88. doi:10.2146/ajhp120118. PMID   23515510.
41. Waldron M, Patterson SD, Tallent J, Jeffries O (May 2018). "The Effects of an Oral Taurine Dose and Supplementation Period on Endurance Exercise Performance in Humans: A Meta-Analysis" (PDF). Sports Medicine. 48 (5): 1247–1253. doi:10.1007/s40279-018-0896-2. PMID   29546641. S2CID   4822875.
42. Pomeroy DE, Tooley KL, Probert B, Wilson A, Kemps E (February 2020). "A Systematic Review of the Effect of Dietary Supplements on Cognitive Performance in Healthy Young Adults and Military Personnel". Nutrients. 12 (2): 545. doi: 10.3390/nu12020545 . PMC   7071459 . PMID   32093203.
43. Jung YP, Earnest CP, Koozehchian M, Galvan E, Dalton R, Walker D, et al. (2017). "Effects of acute ingestion of a pre-workout dietary supplement with and without p-synephrine on resting energy expenditure, cognitive function and exercise performance". Journal of the International Society of Sports Nutrition. 14: 3. doi: 10.1186/s12970-016-0159-2 . PMC   5234109 . PMID   28096758.
44. Baker LB, Nuccio RP, Jeukendrup AE (December 2014). "Acute effects of dietary constituents on motor skill and cognitive performance in athletes". Nutrition Reviews. 72 (12): 790–802. doi: 10.1111/nure.12157 . PMID   25400063.
45. Zaragoza J, Tinsley G, Urbina S, Villa K, Santos E, Juaneza A, et al. (November 2019). "Effects of acute caffeine, theanine and tyrosine supplementation on mental and physical performance in athletes". Journal of the International Society of Sports Nutrition. 16 (1): 56. doi: 10.1186/s12970-019-0326-3 . PMC   6880365 . PMID   31771598.
46. Delecroix B, Abaïdia AE, Leduc C, Dawson B, Dupont G (March 2017). "Curcumin and Piperine Supplementation and Recovery Following Exercise Induced Muscle Damage: A Randomized Controlled Trial". Journal of Sports Science & Medicine. 16 (1): 147–153. PMC   5358025 . PMID   28344463.
47. Directo D, Wong MW, Elam ML, Falcone P, Osmond A, Jo E (June 2019). "The Effects of a Multi-Ingredient Performance Supplement Combined with Resistance Training on Exercise Volume, Muscular Strength, and Body Composition". Sports. 7 (6): 152. doi: 10.3390/sports7060152 . PMC   6628438 . PMID   31242635.
48. Sobolevsky T, Rodchenkov G (2010). "Sulbutiamine in sports". Drug Testing and Analysis. 2 (11–12): 643–6. doi:10.1002/dta.183. PMID   21204296.
49. Fielding R, Riede L, Lugo JP, Bellamine A (March 2018). "l-Carnitine Supplementation in Recovery after Exercise". Nutrients. 10 (3): 349. doi: 10.3390/nu10030349 . PMC   5872767 . PMID   29534031.
50. Sawicka AK, Renzi G, Olek RA (September 2020). "The bright and the dark sides of L-carnitine supplementation: a systematic review". Journal of the International Society of Sports Nutrition. 17 (1): 49. doi: 10.1186/s12970-020-00377-2 . PMC   7507632 . PMID   32958033.
51. Cholewa JM, Guimarães-Ferreira L, Zanchi NE (August 2014). "Effects of betaine on performance and body composition: a review of recent findings and potential mechanisms". Amino Acids. 46 (8): 1785–93. doi:10.1007/s00726-014-1748-5. PMID   24760587. S2CID   18157886.
52. Willingham BD, Ragland TJ, Ormsbee MJ (September 2020). "Betaine Supplementation May Improve Heat Tolerance: Potential Mechanisms in Humans". Nutrients. 12 (10): 2939. doi: 10.3390/nu12102939 . PMC   7599524 . PMID   32992781.
53. Pawar RS, Grundel E (March 2017). "Overview of regulation of dietary supplements in the USA and issues of adulteration with phenethylamines (PEAs)". Drug Testing and Analysis. 9 (3): 500–517. doi:10.1002/dta.1980. PMID   27259162.
54. Cohen PA, Travis JC, Keizers PH, Boyer FE, Venhuis BJ (February 2019). "The stimulant higenamine in weight loss and sports supplements". Clinical Toxicology. 57 (2): 125–130. doi:10.1080/15563650.2018.1497171. PMID   30188222. S2CID   52165506.
55. Kan NW, Lee MC, Tung YT, Chiu CC, Huang CC, Huang WC (September 2018). "The Synergistic Effects of Resveratrol combined with Resistant Training on Exercise Performance and Physiological Adaption". Nutrients. 10 (10): 1360. doi: 10.3390/nu10101360 . PMC   6212981 . PMID   30249003.
56. Alkhatib A, Seijo M, Larumbe E, Naclerio F (2015). "Acute effectiveness of a "fat-loss" product on substrate utilization, perception of hunger, mood state and rate of perceived exertion at rest and during exercise". Journal of the International Society of Sports Nutrition. 12: 44. doi: 10.1186/s12970-015-0105-8 . PMC   4660661 . PMID   26612980.
57. Kuchakulla M, Narasimman M, Soni Y, Leong JY, Patel P, Ramasamy R (May 2020). "A systematic review and evidence-based analysis of ingredients in popular male testosterone and erectile dysfunction supplements". International Journal of Impotence Research. 33 (3): 311–317. doi: 10.1038/s41443-020-0285-x . ISSN   0955-9930. PMID   32358510. S2CID   217167165.
58. Lutsch DJ, Camic CL, Jagim AR, Stefan RR, Cox BJ, Tauber RN, Henert SE (September 2020). "Effects of a Multi-Ingredient Preworkout Supplement Versus Caffeine on Energy Expenditure and Feelings of Fatigue during Low-Intensity Treadmill Exercise in College-Aged Males". Sports. 8 (10): 132. doi: 10.3390/sports8100132 . PMC   7600984 . PMID   32992830.
59. Avula B, Bae JY, Chittiboyina AG, Wang YH, Wang M, Khan IA (September 2019). "Liquid chromatography-quadrupole time of flight mass spectrometric method for targeted analysis of 111 nitrogen-based compounds in weight loss and ergogenic supplements". Journal of Pharmaceutical and Biomedical Analysis. 174: 305–323. doi: 10.1016/j.jpba.2019.05.066 . PMID   31195319. S2CID   189812866.
60. Malykh AG, Sadaie MR (February 2010). "Piracetam and piracetam-like drugs: from basic science to novel clinical applications to CNS disorders". Drugs. 70 (3): 287–312. doi:10.2165/11319230-000000000-00000. PMID   20166767. S2CID   12176745.
61. de Freitas MC, Billaut F, Panissa VL, Rossi FE, Figueiredo C, Caperuto EC, Lira FS (April 2019). "Capsaicin supplementation increases time to exhaustion in high-intensity intermittent exercise without modifying metabolic responses in physically active men". European Journal of Applied Physiology. 119 (4): 971–979. doi:10.1007/s00421-019-04086-w. PMID   30737555. S2CID   59617960.
62. Todorova V, Savova MS, Ivanova S, Ivanov K, Georgiev MI (July 2023). "Anti-Adipogenic Activity of Rhaponticum carthamoides and Its Secondary Metabolites". Nutrients. 15 (13): 3061. doi: 10.3390/nu15133061 . PMC   10346812 . PMID   37447387.
63. Beer C, Keiler AM (July 2022). "Androgenic properties of the dietary supplement 5α-hydroxy-laxogenin". Archives of Toxicology. 96 (7): 2139–2142. doi:10.1007/s00204-022-03283-5. PMC   9151512 . PMID   35344071.
64. Martínez-Sanz JM, Sospedra I, Ortiz CM, Baladía E, Gil-Izquierdo A, Ortiz-Moncada R (October 2017). "Intended or Unintended Doping? A Review of the Presence of Doping Substances in Dietary Supplements Used in Sports". Nutrients. 9 (10): 1093. doi: 10.3390/nu9101093 . PMC   5691710 . PMID   28976928.
65. Leaney AE, Beck P, Biddle S, Brown P, Grace PB, Hudson SC, Mawson DH (August 2020). "Analysis of supplements available to UK consumers purporting to contain selective androgen receptor modulators". Drug Testing and Analysis. 13 (1): 122–127. doi:10.1002/dta.2908. PMID   32748554. S2CID   220965902.
66. "Top Pre-Workout Drink in 2021 | Sports Illustrated Top Reviews". SI. Retrieved 2021-10-19.
67. Roosevelt M (2010-01-13). "When the Gym Isn't Enough". The New York Times. ISSN   0362-4331 . Retrieved 2020-04-03.
68. "Pre-Workout Supplements Market Size, Scope, Share & Forecast". Verified Market Research. Retrieved 2023-09-20.
69. Deldicque L, Francaux M (November 2016). "Potential harmful effects of dietary supplements in sports medicine". Current Opinion in Clinical Nutrition and Metabolic Care. 19 (6): 439–445. doi:10.1097/MCO.0000000000000321. PMID   27552474. S2CID   12979898.
70. Koh AH, Chess-Williams R, Lohning AE (January 2021). "HPLC-UV-QDa analysis of Citrus aurantium-labelled pre-workout supplements suggest only a minority contain the plant extract". Journal of Pharmaceutical and Biomedical Analysis. 193: 113746. doi: 10.1016/j.jpba.2020.113746 . PMID   33190081. S2CID   226973047.
71. Sökmen B, Armstrong LE, Kraemer WJ, Casa DJ, Dias JC, Judelson DA, Maresh CM (May 2008). "Caffeine use in sports: considerations for the athlete". Journal of Strength and Conditioning Research. 22 (3): 978–86. CiteSeerX   10.1.1.524.1504 . doi:10.1519/JSC.0b013e3181660cec. PMID   18438212.
72. Davis JK, Green JM (2009-10-01). "Caffeine and anaerobic performance: ergogenic value and mechanisms of action". Sports Medicine. 39 (10): 813–32. doi:10.2165/11317770-000000000-00000. PMID   19757860. S2CID   31365235.
73. Grgic J, Trexler ET, Lazinica B, Pedisic Z (2018-03-05). "Effects of caffeine intake on muscle strength and power: a systematic review and meta-analysis". Journal of the International Society of Sports Nutrition. 15: 11. doi: 10.1186/s12970-018-0216-0 . PMC   5839013 . PMID   29527137.
74. "What Every Guy Should Know About Pre-Workout Supplements". Men's Health. 2023-07-10. Retrieved 2023-10-06.
75. Blomstrand E, Eliasson J, Karlsson HK, Köhnke R (January 2006). "Branched-chain amino acids activate key enzymes in protein synthesis after physical exercise". The Journal of Nutrition. 136 (1 Suppl): 269S –73S. doi: 10.1093/jn/136.1.269S . PMID   16365096.
76. Newsholme P (September 2001). "Why is L-glutamine metabolism important to cells of the immune system in health, postinjury, surgery or infection?". The Journal of Nutrition. 131 (9 Suppl): 2515S –22S, discussion 2523S-4S. doi: 10.1093/jn/131.9.2515S . PMID   11533304.
77. Hoffman JR, Kang J, Ratamess NA, Hoffman MW, Tranchina CP, Faigenbaum AD (January 2009). "Examination of a pre-exercise, high energy supplement on exercise performance". Journal of the International Society of Sports Nutrition. 6 (1): 2. doi: 10.1186/1550-2783-6-2 . PMC   2621122 . PMID   19126213.
78. Bergstrom HC, Byrd MT, Wallace BJ, Clasey JL (June 2018). "Examination of a Multi-ingredient Preworkout Supplement on Total Volume of Resistance Exercise and Subsequent Strength and Power Performance". Journal of Strength and Conditioning Research. 32 (6): 1479–1490. doi:10.1519/JSC.0000000000002480. PMID   29401192. S2CID   20639856.
79. Martinez, Nic; Campbell, Bill; Franek, Madison; Buchanan, Laura; Colquhoun, Ryan (2016-07-16). "The effect of acute pre-workout supplementation on power and strength performance". Journal of the International Society of Sports Nutrition. 13 (1): 29. doi: 10.1186/s12970-016-0138-7 . ISSN   1550-2783. PMC   4947244 . PMID   27429596.
80. Spradley BD, Crowley KR, Tai CY, Kendall KL, Fukuda DH, Esposito EN, et al. (March 2012). "Ingesting a pre-workout supplement containing caffeine, B-vitamins, amino acids, creatine, and beta-alanine before exercise delays fatigue while improving reaction time and muscular endurance". Nutrition & Metabolism. 9 (1): 28. doi: 10.1186/1743-7075-9-28 . PMC   3361498 . PMID   22463603.
81. Jagim, Andrew R.; Camic, Clayton L.; Harty, Patrick S. (2019-04-16). "Common Habits, Adverse Events, and Opinions Regarding Pre-Workout Supplement Use Among Regular Consumers". Nutrients. 11 (4): 855. doi: 10.3390/nu11040855 . ISSN   2072-6643. PMC   6520716 . PMID   31014016.
82. de Jonge, M. L. L.; Kieviet, L. C.; Sierts, M.; Egberink, L. B.; van der Heyden, M. A. G. (January 2023). "Review of Case Reports on Adverse Events Related to Pre‑workout Supplements Containing Synephrine" (PDF). Cardiovascular Toxicology. 23 (1): 9. doi:10.1007/s12012-022-09777-z. PMC   9859859 . PMID   36639595 . Retrieved September 22, 2023.
83. Sepkowitz, Kent (June 15, 2021). "Energy Drinks and Caffeine-Related Adverse Effects".
84. "Ephedra". Findlaw. Retrieved 2020-04-03.

{{[Get more information on: Is Pre-Workout Bad for You? By RTB Fitness - In Home Personal Training | Online Personal Trainer]}}