Creatine and Performance
Young Ju, Ph.D.
Creatine has been gaining popularity as a non-steroidal performance aid (also called an ergogenic aid). The International Society of Sports Nutrition published an updated position paper regarding the safety and efficacy of creatine supplementation in exercise, sport, and medicine in 2017 (1). If you are considering creatine supplementation, it is important to know what creatine is, what it does, and what dosage is recommended.
What is Creatine?
Creatine is synthesized in the body from amino acids in the liver, kidney, pancreas, and some brain tissues. The body synthesizes 1-3 g of creatine which is about 50% of your daily need (3-5 g or 0.1 g/kg of your body weight). The remaining creatine needed can be obtained from protein-rich foods like meat, fish, and poultry in your diet. Dietary intake of creatine is significantly reduced in individuals following a vegetarian diet (egg and dairy products may provide very small amounts of creatine). In a vegan diet, almost no food source of creatine is consumed. Thus, vegetarians and vegans have lower muscle creatine stores (by 20-30%) than omnivores (2, 3).
While eating protein-rich foods can contribute to increased creatine levels in muscles, creatine supplementation may increase muscle creatine levels more efficiently. Since the 1990s, creatine monohydrate powder has been the most studied and commonly used form (1–5 g/serving) of supplement. Due to its low solubility and instability in solution, creatine is primarily marketed in powder form. Also, one study compared the effectiveness of various creatine forms in reaching peak blood concentration (4), and powder form was the most effective. Several different forms (e.g., creatine salts, creatine in combination with other nutrients, creatine dipeptides, etc.) are advertised as more effective with fewer adverse effects. However, there is no well-designed study showing that these forms more effectively store muscle creatine than creatine monohydrate.
Creatine supplementation reaches its maximum blood concentration in 1-2 hours. About 95% of creatine is stored in muscle; less than 5% is found in other tissues including the heart, brain, and testes (5). In the body, about 2/3 of creatine is bound with phosphate and stored as phosphocreatine; the rest of creatine is stored as free creatine. During exercise, phosphocreatine is broken down into creatine and phosphate. The phosphate is quickly used to generate ATP (a molecule that provides energy) that is then used to power muscle contraction. Creatine and phosphocreatine are further metabolized to creatinine, which is then excreted in the urine. More than 90% of creatine supplements taken by mouth are excreted in the urine (6) (Figure 1).
The common measure of creatine and phosphocreatine levels in the body is a blood test that measures creatine kinase activity. Creatine kinase is found primarily in skeletal and heart muscles, as well as in the brain, and is used to convert creatine to phosphocreatine. A normal creatine kinase level varies by age, sex, muscle mass, and physical activity (adult males: 55-170 units/Liter, adult females: 30-145 units/Liter). High creatine kinase levels can indicate low creatine stores or muscle damage. For more accurate measurement, a non-invasive imaging technique called magnetic resonance spectroscopy can measure creatine or phosphocreatine levels in muscles, brain, and other tissues. Creatine or phosphocreatine levels in the blood do not reflect those levels in muscle.
Figure 1. Creatine Metabolism
What can Creatine Supplementation do?
A substantial amount of research has investigated the beneficial effects of creatine supplementation on muscle strength and performance, bone structure, and brain function across a variety of populations. Researchers also have been investigating the potential therapeutic role of creatine on many health conditions, such as diabetes, sarcopenia, osteoporosis, cancer, rehabilitation, cognition, and heart health, etc. (7).
For athletes and exercising individuals (1, 8), most research studies have used 5-25 g of creatine monohydrate/day supplementation for 4-12 weeks with the following results:
Increased muscle creatine and phosphocreatine levels
Enhanced muscle mass, strength, and exercise capacity
For aging populations (9, 10), most research studies have used 3-25 g of creatine monohydrate/day for 7-26 weeks resulting in:
Improved muscle mass, strength, bone and body composition
Support for cognitive function
Support for healthy glucose management
Support for heart metabolism and heart health
Dose of Creatine Supplementation (11)
Factors that should be considered in determining an optimal dose for an individual include muscle health status, creatine stores in the body, dietary creatine intake, sex, age, and physical activity, etc. Factors that influence an individual’s responsiveness to creatine still need to be determined. Dosing strategies include the following:
Loading: Used to fully saturate the muscle stores in several days (20 g/day for 5-7 days)
Maintenance: May take up to 28 days to saturate (3-5 g/day)
Relative Dosing Strategy: An individualized approach for people with different needs (0.1-0.14 g/kg body weight/day), e.g., to improve better muscle creatine uptake for older adults or to supply adequate amounts of creatine for people who might have larger creatine stores.
Usually, athletes take the loading dose followed by a maintenance dose. However, accumulating evidence suggests that taking 3-5 g of creatine supplements per day effectively increases muscle creatine stores and muscle performance and recovery without a loading dose (12). Daily dietary creatine needs may be 3-5 g/day to promote general health (1).
Timing of Creatine Supplementation (13)
Timing of creatine supplementation has been also investigated to optimize muscle loading and to maximize performance. Consistent research findings show that:
Creatine supplementation increases creatine levels in muscle and improves exercise performance.
Creatine supplementation taken close to exercise appears to have greater benefits compared to ingesting farther from exercise time.
Several factors including age, diet, and exercise may influence these responses.
Questions remain whether pre-exercise supplementation is more effective in enhancing creatine levels in muscle than post-exercise and whether the timing of creatine supplementation influences creatine levels in muscle and improves performance in the long term.
Potential Adverse Effects of Creatine Supplementation (14)
Creatine supplementation rarely has adverse effects when it’s used within recommended dosages. Taking higher than recommended doses may cause:
Water retention and weight gain: creatine could increase water uptake into muscle cells, leading to a temporary weight gain.
Muscle cramps: could cause dehydration or muscle compartment pressure
Digestive problems: stomach upset, bloating, or diarrhea
Kidney concerns: excessive intake of creatine with inadequate hydration could burden the kidneys. People with kidney disease should discuss with their doctor prior to taking creatine.
Interaction with certain medications: Taking creatine with nonsteroidal anti-inflammatory drugs (e.g., Advil, Aleve, Aspirin etc.) can increase the risk of kidney damage.
Conclusion
Research evidence suggests that creatine is an effective performance/ergogenic aid that produces energy for improved muscle mass, performance, and recovery in athletes and exercising people. The International Society of Sports Nutrition, the American Dietetic Association, and the American College of Sports Medicine have reached similar conclusions with one calling it: “the most effective ergogenic nutritional supplement currently available to athletes in terms of increasing high-intensity exercise capacity and lean body mass during training” (1, 15). For most adults, 3-5 g of creatine daily is considered safe. You should take creatine with plenty of water to prevent potential side effects and increase your dosage gradually to minimize digestive problems. As always, if you are considering taking a supplement, you should self educate as well as consult your medical professional.
Dr. Young Ju is a Ph.D and Associate Professor of Human Nutrition, Foods, and Exercise at Virginia Tech.
References
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Green et al. Carbohydrate ingestion augments skeletal muscle creatine accumulation during creatine supplementation in humans. Am J Physiol. 1996;271(5 Pt 1):E821–E826.
Harris et al. Absorption of creatine supplied as a drink, in meat or in solid form. J Sports Sci 2002, 20(2): 147.
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Cordingley et al. Anti-inflammatory and anti-catabolic effects of creatine supplementation: A brief review. Nutrients 2022, 14(3):544.
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Candow et al. Does one dose of creatine supplementation fit all? Advanced Exercise Health Sci. 2024, 1(2):99.
Antonio et al. Common questions and misconceptions about creatine supplementation: what does the scientific evidence really show? J Int Soc Sports Nutr. 2021, 18:13.
Ribeiro et al. Timing of creatine supplementation around exercise: A real concern? Nutrients 2021, 13(8):2844.
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Thomas et al. Position of the Academy of Nutrition and Dietetics Dietitians of Canada, and the American College of Sports Medicine: Nutrition and athletic performance. J Acad Nutr Diet. 2016, 116:501.
This information is provided for your reference and you use at your own risk; you should rely on your medical professional for medical advice.
