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Creatine and its effects on performance

Creatine is one of the most popular supplements among athletes, and unlike many of the supplements on the market, it has an excellent evidence base for its positive effects on sports performance and metabolism.

What is creatine?

Creatine is a natural compound that is produced in the body from amino acids, though it can also be found in foods like red meat and some fish. Creatine is mostly found in the muscles as ‘free’ creatine or as phosphocreatine, where it has an essential role in powering exercise and movement (1). Phosphocreatine is responsible for quickly restoring levels of ATP in the muscle, which is often known as the ‘energy currency’ of cells. ATP is broken down when muscles contract during exercise or other activity, and although the body can produce more ATP from fuel sources like carbohydrate and fat, these are relatively slow processes. Phosphocreatine provides a quick pool of energy to allow rapid restoration of ATP, and therefore fuel for high intensity exercise. Creatine only exists in small amounts in the body, enough to fuel around 10 seconds of high intensity activity (2).

Supplementing with creatine increases the amount of creatine in the body by up to 30%. There are many different types of creatine available on the market, but the simplest and most researched form is creatine monohydrate. It is also the cheapest, with other types of creatine (such as creatine ethyl ester or creatine hydrochloride) not having been proven to be superior (3). The standard dosing of creatine is 3-5g per day. Although many of the earliest studies used ‘loading phases’ of creatine of 20-30g per day to saturate stores quickly, smaller doses are equally effective, but simply take a little longer to build up in the body and have an effect.

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Safety and side effects

Creatine is one of the most widely researched supplements, with decades of evidence behind it. Creatine supplementation is safe for healthy people, and although some people claim that there are links to cancer, heart disease and even hair loss, there is no evidence for such claims. Even very long-term supplementation with high doses has been investigated and has shown no negative effects in healthy people (2).

Creatine is one of the most widely researched supplements, with decades of evidence behind it.

Creatine does have some side-effects which are worth knowing about. The most common side effect is weight gain which occurs because creatine causes retention of water in muscles. This side effect varies and not all people experience it, though it is common to gain 1-3 kg (2-7 lbs). Creatine does sometimes cause mild stomach discomfort in some people when taking large doses. However, studies specifically investigating side effects fail to show any more serious side effects such as increased injury risk, dehydration, kidney dysfunction or stomach upset (2).

Power and strength sports

Creatine is a very popular supplement for strength and power athletes, where events generally last <30s. It can augment increases in muscle mass and strength during resistance training, as well as improve performance in competition (1). In such sports, the increase in body weight is generally not problematic, as the increase in performance more than compensates for the increased body mass. Such sports that benefit from creatine supplementation include 100m and 200m sprints, weightlifting and powerlifting and sprint swimming.

Intermittent sports

Creatine supplementation is beneficial in sports involving intermittent high intensity exercise and has been shown to improve performance of measures like repeated sprint speed and jump height (4). These benefits are potentially helpful in common team sports like soccer, football or basketball. In these sports, the positive effects of creatine with resistance training on muscle mass and strength may also be beneficial. Although laboratory-based studies looking at specific measures of power output and speed are improved with creatine supplementation, more sport specific field-based studies of the sports themselves are less likely to see such improvements with creatine supplementation (5).

Creatine is beneficial for intermittent high intensity sports as supplementation has been shown to improve performance of measures like repeated sprint speed and jump height.

Endurance sports

The positive effects of creatine on performance generally reduce as exercise duration increases. In endurance sports, the need for high intensity ‘bursts’ is more limited compared to intermittent sports like soccer. The findings of studies on endurance sports are mixed, though most show no benefit of creatine supplementation (6-8). Unlike resistance training, supplementing with creatine while doing endurance training has been shown not to improve or enhance adaptations to training (9). Because creatine supplementation can increase body weight it could be problematic in endurance sports, where an increase in body weight increases energy requirements and requires greater power output. Some studies do show a benefit of creatine supplementation in endurance exercise in lab-based tests (10,11). For example, many of these studies investigate cycling using stationary bikes, where any increase in body weight is not a factor affecting performance. Therefore, it is possible that creatine in some scenarios in endurance sports might be beneficial, for example there is often a need for higher power output or speed in the sprint finish at the end of a race, or in a climb during the race. At these times, phosphocreatine contributes a lot to energy production, and so increased creatine stores may be helpful. However, the increase in body weight that accompanies creatine is sufficient to cancel out the possible small benefits in most scenarios.

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  1. Butts J, Jacobs B, Silvis M. Creatine Use in Sports. Sports Health: A Multidisciplinary Approach. 10(1):31-4, 2018

  2. Kreider RB, Kalman DS, Antonio J, Ziegenfuss TN, Wildman R, Collins R, Candow DG, Kleiner SM, Almada AL, Lopez HL. International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine. J Int Soc Sports Nutr. 14:18, 2017

  3. Jäger R, Purpura M, Shao D, Inoue T, Kreider RB. Analysis of the efficacy, safety, and regulatory status of novel forms of creatine. Amino Acids. 40(5):1369-83, 2011

  4. Ramírez-Campillo R, González-Jurado JA, Martínez C, Nakamura FY, Peñailillo L, Meylan CMP, Caniuqueo A, Cañas-Jamet R, Moran J, Alonso-Martínez AM, Izquierdo M. Effects of plyometric training and creatine supplementation on maximal-intensity exercise and endurance in female soccer players. J Sci Med Sport. 19(8):682-7, 2016

  5. Williams J, Abt G, Kilding A. Effects of Creatine Monohydrate Supplementation on Simulated Soccer Performance. Int J Sports Physiol Perform. 9(3):503-10, 2014

  6. van Loon LJ, Oosterlaar A, Hartgens F, Hesselink M, Snow R, Wagenmakers AJM. Effects of creatine loading and prolonged creatine supplementation on body composition, fuel selection, sprint and endurance performance in humans. Clin Sci. 104(2):153-62. 2003

  7. Cooper R, Naclerio F, Allgrove J, Jiminez A. Creatine supplementation with specific view to exercise/sports performance: an update. J Int Soc Sports Nutr. 9(1):33, 2012

  8. Van Schuylenbergh R, Van Leemputte M, Hespel P. Effects of oral creatine-pyruvate supplementation in cycling performance. Int J Sports Med. 24(2):144-50, 2003

  9. Reardon T, Ruell P, Fiatarone Singh M, Thompson C, Rooney K. Creatine supplementation does not enhance submaximal aerobic training adaptations in healthy young men and women. Eur J Appl Physiol. 98(3):234-41, 2006

  10. Murphy A, Watsford M, Coutts AJ, Richards D. Effects of creatine supplementation on aerobic power and cardiovascular structure and function. J Sci Med Sport. 8(3):305-13, 2005

  11. Kilduff L, Gerogiades E, James N, Minnion R, Mitchell M, Kingsmore D, Hadjicharlambous M, Pitsiladis Y. The effects of creatine supplementation on cardiovascular, metabolic, and thermoregulatory responses during exercise in the heat in endurance-trained humans. Int J Sport Nutr Exerc Metab. 14(4):443-60, 2004


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