Creatine

Creatine is a nitrogen-containing compound made from amino acids. The body produces about 1–3g a day in organs such as the liver and kidneys, and it is also obtained from red meat and seafood, such as beef and salmon. Most of the body's creatine is stored in muscle, with a substantial proportion held in reserve as phosphocreatine (PCr).

The energy muscles use comes from a molecule called ATP. However, muscles store only a small amount of ATP, so it is quickly depleted during short, intense efforts such as sprinting or lifting heavy weights. Phosphocreatine then supplies a phosphate group to rapidly regenerate ATP. This rapid energy-replenishment pathway is covered in detail in Energy systems. Creatine supplementation increases creatine stores in muscle, which is described as providing the capacity for an extra repetition during explosive exercise lasting a few seconds to tens of seconds.

Creatine and creatine kinase have similar names but are different substances. Creatine is a compound, while creatine kinase is the enzyme that catalyzes this reaction.

A position statement from the International Society of Sports Nutrition (2017) concluded that creatine monohydrate is among the most effective supplements for supporting high-intensity exercise performance and training adaptations. A 2024 meta-analysis of adults under 50 reported greater average strength gains in groups that combined creatine with resistance training than in groups that performed resistance training alone. A tendency for fat-free body mass to increase has also been reported. Early on, increased water in the muscles accounts for much of the change, and many people gain 1–2kg. Results can vary depending on body water and the method used to measure fat-free mass, so rather than interpreting all weight gain as an increase in muscle protein, it is helpful to consider training, diet, and measurement conditions together (Fat-free mass).

The following approaches are widely described in studies and position statements.

• Loading approach — Take about 0.3g per 1kg of body weight, usually around 20g a day divided into 4 doses, for 5–7 days, then switch to a maintenance dose. This approach is intended to fill muscle stores quickly.
• Maintenance approach — Take 3–5g a day consistently. Even without loading, this alone fills stores over several weeks.
• Form — Monohydrate powder is the most extensively studied form. It can be mixed into water, juice, or a protein shake.
• Timing — Take it at a convenient time of day, whether before or after exercise or with a meal. Consistent intake is important.
• Fluids — Because water increases in the muscles, continue drinking enough water as usual.

Creatine can be obtained by eating red meat and fish, but getting the amounts used in studies through food alone would require large quantities. People who follow vegetarian diets are reported to tend to have lower muscle creatine stores.

• People who repeatedly lift heavy weights in activities such as gym workouts, CrossFit, or weightlifting
• People who repeat short, intense efforts in activities such as sprinting or ball sports
• People seeking to increase muscle mass through strength training
• Its use alongside strength training in older adults is also being studied

• Check the product. Even among creatine products, the amount and added ingredients vary. Check the label for the amount of creatine monohydrate and other ingredients (Dietary supplements).
• Weight changes. Weight gain is common during the first few weeks after starting. Most of this is due to increased water in the muscles.
• Stomach discomfort. Taking a large amount at once can cause stomach discomfort, so loading doses are divided into several smaller doses.
• Medical tests. Taking creatine can affect blood creatinine levels. Let your healthcare provider know that you take the supplement when having a health checkup or kidney-related tests.
• If you have kidney disease or take medication. Consult a doctor or pharmacist before starting.
• With other supplements. Many people take it with caffeine or protein. For protein, see Protein supplements; for caffeine, see Caffeine and exercise performance.