B.L.U.F.*

Creatine supplements may be helpful to Warfighters whose missions require upper-body strength and repeated, short bursts of activity. Creatine will not help develop military skill, endurance, or agility.

Background

Creatine is one of the most popular dietary supplements in the military and athletic communities for the enhancement of short-term energy. It occurs naturally in the human body and in dietary sources such as meat, poultry, and fish. It is available as a supplement and is generally considered a “natural” way to enhance physical performance and build muscle mass. It is not considered an illegal substance by most athletic governing bodies or the military.

Myths and Claims

Creatine is generally believed to be a safe dietary supplement, and no serious adverse effects have been reported in the scientific literature, although a few side effects have been noted (see Cautions below). Editorials and articles in the media have created some controversy over its use. Among the misconceptions about the use of creatine are that: associated weight gain is entirely due to water retention; renal distress, cramping, dehydration, and altered electrolyte status may occur; long-term effects are completely unknown; newer formulations are more beneficial and cause fewer side effects; and it is unethical and/or illegal to use creatine supplements.

Facts

Creatine occurs in the human body almost entirely in skeletal muscles, mostly in fast twitch muscles. About 60% occurs as creatine phosphate (CP), which participates in energy production and assists the initiation of muscle action, especially during short, high-intensity physical activities. Creatine supplements increase the concentration of CP in skeletal muscles, enhancing short-term performance in high-intensity activities. Combined with resistance training, creatine supplements can contribute to building fat-free mass, muscle power and dynamic strength, force output, and total work in both men and women, although not all users respond to its use. Creatine also may improve cognitive and psychomotor performance and mood following sleep deprivation. There is, however, no evidence that it improves endurance, skill, or agility.

Cautions

The most common side effect of creatine is weight gain; the amount depends on length of use and dosing. A few studies have reported increased pressure in lower-leg muscles. Claims of adverse effects such as muscle cramping, gastrointestinal disturbances, renal dysfunction, dehydration, and heat intolerance have not been supported by larger studies, and some of the reported cases may have been associated with creatine ingestion timing or dosing, co-ingestion of other substances, and/or intensity of exercise.

Summary for Military Relevance

Few studies have focused on the effectiveness of creatine during military mission scenarios, and the results of those few are ambiguous. The most encouraging indicators are for building upper body strength, and creatine shows some promise for protection against traumatic brain injury. There is very little study of its use in extreme environments, notably none on extreme cold and high-altitude conditions; limited data indicate no impact on tolerance of hot environments. Warfighters involved in repeated, short bouts of high-intensity activity—such as sprinting and climbing—and those who require upper body strength—as in equipment lifting and buddy-lift/carry—have the most to gain from creatine supplements. Specific recommendations for creatine use by Warfighters include: (1) monitoring of weight, urinalysis, and metabolic panel by a health professional; (2) daily dosing of two to three grams, possibly alternating four weeks of use with a four-week washout period; and (3) using only creatine supplements marked with a third-party testing laboratory seal such as USP to ensure product grade. Creatine supplements should not be used (a) if weight loss is desired, (b) in environments of extreme temperatures or altitude, especially when adequate hydration cannot be maintained, (c) when a physician cannot be consulted every 6-12 months for monitoring, and (d) when the user’s goal is only to improve overall endurance. Most important, creatine’s benefits do not translate into greater military skill, endurance, or agility.

* Bottom Line Up Front

Key Points

• Creatine, a compound found naturally in the body, is a key player in energy production, particularly within skeletal muscles.
• The creatine stored in skeletal muscles replenishes energy stores during the onset of exercise.
• Creatine supplements may enhance explosive strength or performance of short-term bouts of high-intensity physical activities if used in conjunction with proper training.
• Creatine supplements do not appear to improve performance of endurance activities such as long-distance running.
• Not everyone who takes creatine supplements sees performance improvements or gains in muscle mass; the reasons are not completely understood, but may relate to genetic and dietary differences.
• The use of creatine is believed to be safe, but it has been shown to increase pressure within the anterior compartment of the lower leg muscles in some individuals.
• A safe and effective dose of creatine is two to three grams per day; this dose is sufficient to maximize muscle creatine levels. A loading phase is not necessary.
• As with any dietary supplement or workout regimen, always maintain optimal hydration status.
• Users should always discuss their consumption of dietary supplements with a health-care professional.
• When purchasing creatine supplements, look for a United States Pharmacopeia (USP) seal or independent research company approval (NSF), which ensure product purity and grade.
• Creatine should be used alone as creatine monohydrate, not in combination with other multiple ingredients.
• Creatine may improve Warfighter performance in activities comparable to those used in research studies, such as short bouts of high-intensity activities.

Background

The use of dietary supplements has become increasingly popular among members of the military community, and creatine is one of the most widely used supplements. It is taken to increase performance, but it has been surrounded by much controversy. The following sections will discuss the current literature on creatine, its impact on performance, and how this information may be translated into the military community.

History

Creatine was first discovered in the early 1830s by Chevreul and confirmed by Liebeg in 1847 as an organic constituent of meat, who also theorized that creatine was somehow linked to muscle performance. However, the investigation of creatine as an oral supplement soared later (in the early 1900s) with the extraction of creatine from meat [1]. In the 1970s, Soviet scientists reported that oral creatine supplements might improve athletic performance during brief, intense activities such as sprints. Consequently, creatine gained popularity a few decades later as a "natural" way to enhance athletic performance and build muscle mass. The purchase and use of creatine increased substantially, as did scientific investigations to examine its merits. Currently, creatine is one of the most widely used dietary supplements taken by athletes and the military community to increase physical performance. Many governing bodies for sports and athletics, such as the International Olympic Committee (IOC), do not consider creatine an illegal substance [2]. Neither has the military banned the use of creatine supplements.

Synthesis and mechanism of action

Creatine is a non-protein nitrogen compound that can either be ingested through dietary sources such as meat, poultry, and fish, or made by the human body from the non-essential amino acids arginine, glycine, and methionine by the liver, kidneys, and pancreas [1]. Approximately 95% of the body's total creatine content (120 to 140 g for an average 155 lb/70 kg person) is located in skeletal muscles, with a greater concentration in Type II (fast twitch) than in Type I (slow twitch) muscle fibers [1]. The remaining five percent is located in the brain and heart [3]. Creatine is converted in skeletal muscle to creatinine and then filtered by the kidneys at a rate of about one to two grams/day for excretion in urine [2].

Creatine typically exists in one of two forms in the body: free creatine, which accounts for approximately 40%, and a phosphorylated form, creatine phosphate (CP), which accounts for the rest [4]. Creatine phosphate participates directly in energy production and serves as the cells’ energy reservoir to provide rapid phosphate-bond energy to resynthesize adenosine triphosphate (ATP) from adenosine diphosphate (ADP) and phosphate. Creatine and CP also act to shuttle high-energy phosphates between the mitochondria and muscle-filament cross-bridge sites to initiate and maintain muscle action [2]. During short, high-intensity physical activities, CP is hydrolyzed and contributes about 50% of its total phosphate to meet the requirements for ATP. These levels decline rapidly in skeletal muscle during the first few seconds of exercise. Theoretically, if CP levels could be sustained, ATP demand would be met during muscle contraction, and performance of physical tasks requiring maximal effort should improve [5]. However, as exercise duration increases and intensity decreases, oxidative phosphorylation and glycolysis become more important sources of ATP and high-energy phosphates than CP.

Benefits

The major creatine supplement sold is creatine monohydrate (Cr•H₂0), which comes as powder, tablet, capsule, or stabilized liquid [2]. Creatine supplements increase the concentration of CP in skeletal muscles, which enhances performance of short-term bouts of high-intensity activities. In addition, creatine supplementation in combination with resistance training can result in an average gain of two to five pounds of fat-free mass and an average gain of five to 15% of muscle power, dynamic strength, force output, and total work [1,6]. Although studies have focused mostly on men, similar results have been found in women [6]. There is little or no evidence to suggest improvements in endurance or aerobic performance in either men or women [6].

Creatine may also have some psychological benefits. A recent finding showed that creatine supplementation produced a positive effect on cognitive and psychomotor performance and mood state following 24 hours of sleep deprivation [7]. This benefit may reflect increases in brain creatine content due to creatine supplementation [3]. In addition, evidence from animal studies suggests creatine intake may be useful in protecting against traumatic brain injury, now often referred to as the signature wound of the Iraq and Afghanistan wars [8]. Perhaps this effect is due to improved mitochondrial bioenergetics [8].

Taken together, the available evidence suggests that creatine supplementation probably increases lean muscle mass, enhances performance of repeated bouts of short, high-intensity physical activities, and possibly improves cognitive and psychomotor performance. However, there are “responders” and “non-responders” to creatine supplementation [4], and non-responsiveness to creatine supplements may suggest an already optimal pool of CP [6] or, possibly, genetic differences. The underlying physiological mechanism to explain the ergogenic effects of creatine remains unclear.

Dosing

The optimal dosing strategy for creatine has not been established. However, two to three grams/day of creatine is a safe and effective dose to maximize muscle creatine levels [9]. Prior to 2006, investigators studied numerous dosing regimens, with one of the original creatine supplementation protocols requiring a loading phase of 20-25 g/day of creatine (divided into four to five doses per day) for five to seven days, followed by a "maintenance" dose of three to five grams/day [4]. After only a three-day period of loading, urinary creatine increased by 60%, suggesting that muscle stores were maximally saturated. Subsequent studies showed three grams/day for 28 days without loading yielded similar muscle creatine concentrations as with loading [4,10]. This finding led to the conclusion that three grams/day of creatine would be sufficient for raising tissue levels [10]. In addition, creatine use can be cycled wherein creatine is taken for four weeks followed by a four-week washout period [10].

Military performance

The use of creatine supplements is very popular within the military, especially within Special Operations Forces (SOF) communities. However, few studies have examined creatine use during mission scenarios. In one study, Bennett et al. [5], demonstrated that five grams/day of creatine for four weeks, as compared to a placebo, increased the upper body strength of U.S. Army Rangers as measured by performing pull-ups after a 10-mile march with a pack. However, creatine did not improve performance with respect to time to complete a 10-mile march, speed of climbing up and down stairs with a pack, or strength and endurance of handgrip. In contrast, a more recent study conducted with active-duty U.S. Army men and women did not find a difference in two-minute push-up counts between those using creatine supplementation and control groups [11]. Although inconsistencies are found in the military population, improvements in upper body strength are consistent across the literature on athletes. This suggests that Warfighters whose tasks include repeated upper body actions might benefit from using creatine.

Researchers need to investigate the effects of creatine supplementation in extreme environments, as Warfighters frequently operate in severe cold and heat and at high altitudes. At present, no data are available on creatine use and tolerance of cold or effects at high altitudes [6]. The limited data available on the tolerance of thermal stress suggests no impact [5,12]. In addition, improved mood, cognition, and psychomotor performance, as well as possible protection against traumatic brain injury [7,8], are potentially cogent benefits for the military.

In the military, optimizing performance is not a matter of winning or losing an athletic event, but rather a matter of mission effectiveness and possibly survival. Based on the benefits discussed earlier and the few studies conducted in the military community, creatine may have some useful applications. However, in certain situations, it could potentially compromise performance if not used appropriately.

Myths and/or Claims

Creatine supplementation has been surrounded by much controversy resulting in several misconceptions. The International Society of Sports Nutrition issued a position statement [13] in which the following common conceptions (discussed further under Facts and Cautions) were reported:

• All weight gained during supplementation is due to water retention.
• Creatine supplementation causes renal distress, cramping, dehydration, and/or altered electrolyte status.
• Long-term effects of creatine supplementation are completely unknown.
• Newer creatine formulations are more beneficial than Cr•H₂0 and cause fewer side effects.
• It is unethical and/or illegal to use creatine supplements.

Facts and Evidence

Based on scientific evidence, creatine supplementation can increase muscle mass if used in conjunction with proper training. And according to current research, creatine is safe. Scientific evidence to date suggests that individuals taking creatine have no greater risk of renal distress, cramping, dehydration, and/or altered electrolyte status than those not taking supplements, although cramping has been reported and studies have shown an increase in pressure within the anterior compartment of the lower leg muscles. To ensure safety, users of creatine should consult a health-care professional prior to and during use. In addition, no major side effects have been seen for up to five years in users of creatine supplementation. Moreover, most of the newer creatine formulations are usually no better than traditional Cr•H₂0 in terms of increasing strength or performance. Selected formulations may produce greater effects than Cr•H₂0 [13], but conclusive studies are needed. Finally, creatine is not considered an illegal substance by most sports’ governing bodies, including the International Olympic Committee.

Cautions

No serious adverse effects from the use of creatine supplementation for up to five years have been reported in the scientific literature. However, a few side effects have been reported. By far the most common side effect of creatine is weight gain. Weight gain is between 0.5-1.0 kg with short term-use and up to 10 kg with longer-term use, depending on the dose [10]. Also, a few studies reported increased pressure within the anterior compartment of the lower leg muscles [14-16]. Despite the lack of evidence for adverse events, case reports in the scientific literature—and in editorials and papers published in the sports and media—often indicate otherwise. Reported conditions include muscle cramping, gastrointestinal disturbances, renal dysfunction, dehydration, and heat intolerance. These adverse events have not been confirmed in larger studies and may have to do with the timing of creatine ingestion and/or co-ingestion of other substances [4,6]. Reports of muscle cramping may reflect the intensity of exercise, as supplementation may cause users to exercise at a level of intensity greater than optimal. No studies demonstrate any renal or liver dysfunction or any heat intolerance when recommended amounts of creatine are used [17]. However, to ensure safety, users of creatine should consult a health-care professional. And health-care professionals should monitor persons using creatine every six to 12 months. Periodic assessments could include weight monitoring, urinalysis, and a comprehensive metabolic panel.

Military Relevance

Creatine provides the most beneficial effects for performance when the activity involves repeated, short bouts of high-intensity exercise [1]. Thus, individuals in the military community engaged in these types of activities are likely to see the greatest benefit from creatine supplementation. In addition, these benefits are not gender or age dependent, although some conflicting evidence with regard to age exists in the published literature [1]. Moreover, the potential ergogenic effects of creatine may vary in individuals, as some may be responders and others non-responders. In addition, research is lacking on creatine use in extreme environments by the military. Hence, it is not known if the use of creatine under these conditions confers any additional benefit.

Despite the limited data on military populations, it is important to recognize that, from both an operational and training perspective, creatine supplementation consistently leads to gains in body mass and increased upper body strength. These conclusions can then be applied logically to such tasks within the military environment, as well as the performance of missions that involve sprinting and heavy lifting (climbing, equipment carrying, buddy-carry/lift)—important military tasks that research has shown to be sustained when personnel use creatine. However, it is imperative to note that performance benefits such as increases in strength and/or ability to perform intense, short-term bouts of activity do not translate into improved endurance, skill, or agility. It is unlikely creatine will benefit marching or other such endurance activities, particularly if weight gains are large. However, no data suggest that proper creatine supplementation will compromise these tasks.

Summary

Whether creatine supplementation will help sustain human performance on the battlefield is unknown. Understanding mission physical requirements and knowing which activities might most be enhanced with creatine supplementation might be the most effective criteria to determine whether creatine should be used. The following guidelines should be considered for Warfighter creatine use:

• Creatine should not be used when (a) the goal is weight loss; (b) personnel are working in extreme heat, cold, or altitude and with limited water supply; (c) access to a health-care professional is limited or non-existent for long periods of time; or (d) the goal is only to improve overall endurance.
• A health-care professional should monitor persons using creatine—including weight tracking, a urinalysis, and a comprehensive metabolic panel—every six to 12 months.
• A maintenance dose of two-three grams/day, without a loading phase, is adequate. Also, the use of creatine may be cycled, wherein creatine is taken for four weeks followed by a four-week washout period.
• The quality of the creatine and the manufacturing standards used are essential to ensure safe use of this supplement in any environment. Evidence of third-party laboratory testing such as a United States Pharmacopeia (USP) seal is critical.

1. Bemben MG, Lamont HS. Creatine supplementation and exercise performance: recent findings. Sports Med. 2005;35(2):107-25.McArdle W, Katch F, Katch V. Exercise physiology: energy, nutrition, and human performance. 6th ed: Williams & Wilkins; 2007.
2. Dechent P, Pouwels PJ, Wilken B, Hanefeld F, et al. Increase of total creatine in human brain after oral supplementation of creatine-monohydrate. Am J Physiol. 1999;277(3 Pt 2):R698-704.
3. Demant TW, Rhodes EC. Effects of creatine supplementation on exercise performance. Sports Med. 1999;28(1):49-60.
4. Bennett T, Bathalon G, Armstrong D, 3rd, Martin B, et al. Effect of creatine on performance of militarily relevant tasks and soldier health. Mil Med. 2001;166(11):996-1002.
5. Greenwood M, Oria M. Use of Dietary Supplements by Military Personnel: Natl Academy Pr; 2008.
6. McMorris T, Harris RC, Swain J, Corbett J, et al. Effect of creatine supplementation and sleep deprivation, with mild exercise, on cognitive and psychomotor performance, mood state, and plasma concentrations of catecholamines and cortisol. Psychopharmacology (Berl). 2006;185(1):93-103.
7. Scheff SW, Dhillon HS. Creatine-enhanced diet alters levels of lactate and free fatty acids after experimental brain injury. Neurochem Res. 2004;29(2):469-79.
8. Poortmans JR, Rawson ES, Burke LM, Stear SJ, et al. A-Z of nutritional supplements: dietary supplements, sports nutrition foods and ergogenic aids for health and performance Part 11. Br J Sports Med. 2010;44(10):765-6.
9. Hultman E, Soderlund K, Timmons JA, Cederblad G, et al. Muscle creatine loading in men. J Appl Physiol. 1996;81(1):232-7.
10. Armentano MJ, Brenner AK, Hedman TL, Solomon ZT, et al. The effect and safety of short-term creatine supplementation on performance of push-ups. Mil Med. 2007;172(3):312-7.
11. Lopez RM, Casa DJ, McDermott BP, Ganio MS, et al. Does creatine supplementation hinder exercise heat tolerance or hydration status? A systematic review with meta-analyses. J Athl Train. 2009;44(2):215-23.
12. Buford TW, Kreider RB, Stout JR, Greenwood M, et al. International Society of Sports Nutrition position stand: creatine supplementation and exercise. J Int Soc Sports Nutr. 2007;4:6.
13. Hile AM, Anderson JM, Fiala KA, Stevenson JH, et al. Creatine supplementation and anterior compartment pressure during exercise in the heat in dehydrated men. J Athl Train. 2006;41(1):30-5.
14. Potteiger JA, Carper MJ, Randall JC, Magee LJ, et al. Changes in Lower Leg Anterior Compartment Pressure Before, During, and After Creatine Supplementation. J Athl Train. 2002;37(2):157-63.
15. Potteiger JA, Randall JC, Schroeder C, Magee LM, et al. Elevated Anterior Compartment Pressure in the Leg After Creatine Supplementation: A Controlled Case Report. J Athl Train. 2001;36(1):85-8.
16. Poortmans JR, Francaux M. Adverse effects of creatine supplementation: fact or fiction? Sports Med. 2000;30(3):155-70.