Creatine: What It Actually Does for Muscle, Strength, and Endurance

A look at the evidence behind one of the most studied supplements in sports nutrition.

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By the Ration Editorial Team · Reviewed against primary research · Updated July 13, 2026

Creatine is a compound made naturally in the liver, kidneys, and pancreas from amino acids.

It is also found in foods like meat and fish, and stored mostly in skeletal muscle.

Muscle uses creatine to regenerate ATP, the cell's quick energy currency, during short bursts of intense effort like lifting or sprinting.

Supplementing with creatine raises the amount stored in muscle as phosphocreatine.

This gives muscle a faster way to replenish ATP during high intensity, short duration activity, which can support more reps, sets, or power output over a training session^[9][10].

Over weeks of training, that extra work capacity is thought to be a major driver of the muscle growth seen in trials^[5].

This is where the evidence is strongest.

A 2025 randomized controlled trial found creatine increased lean body mass, with larger gains when combined with resistance training^[1].

A 2023 meta-analysis focused specifically on muscle hypertrophy found creatine combined with resistance training produced greater regional muscle growth than training alone^[5].

This benefit is not limited to young athletes.

• A 2022 meta-analysis found creatine improved lean body mass across different ages, sexes, and exercise types^[6]
• Meta-analyses in older adults specifically found creatine plus resistance training improved lean tissue mass and strength^[8][12]
• Research in children and adolescents has also examined creatine use, generally in supervised or clinical contexts^[7]
• A narrative review highlights potential benefits for women, vegans, and certain clinical populations, groups that may have lower baseline creatine stores^[3]

Taken together, this body of evidence earns creatine's effect on lean body mass a strong, consistent grade in our database.

• ↑Lean Body MassAHuman trials

  Research may raise Lean Body Mass · strong agreement · 6 studies

  View 5 studies on PubMed

  • Influence of age, sex, and type of exercise on the efficacy of creatine supplementation on lean body mass: A systematic review and meta-analysis of randomized clinical trials (2022)
  • The Effects of Creatine Supplementation Combined with Resistance Training on Regional Measures of Muscle Hypertrophy: A Systematic Review with Meta-Analysis (2023)
  • Meta-Analysis Examining the Importance of Creatine Ingestion Strategies on Lean Tissue Mass and Strength in Older Adults (2021)
  • The Effect of Creatine Supplementation on Lean Body Mass with and Without Resistance Training (2025)
  • Creatine Supplementation: An Update (2021)
• ↑VO2maxDPreliminary

  Research may raise VO2max · strong agreement · 6 studies

  View 5 studies on PubMed

  • Creatine for Exercise and Sports Performance, with Recovery Considerations for Healthy Populations (2021)
  • International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine (2017)
  • The Top 5 Can't-Miss Sport Supplements (2024)
  • Creatine Supplementation Beyond Athletics: Benefits of Different Types of Creatine for Women, Vegans, and Clinical Populations-A Narrative Review (2024)
  • Creatine Supplementation in Children and Adolescents (2021)

The contrast between these two outcomes is instructive.

Lean body mass has six sources behind it and a consensus 'increase' with a top evidence grade, reflecting randomized trials and multiple meta-analyses that largely agree^{[1][5][6][8][12]}.

VO2max, a marker of aerobic endurance capacity, also shows a directional increase across six sources, but the evidence grade is low.

A 2023 review of creatine and endurance performance describes benefits mainly in efforts involving repeated sprints or surges rather than steady state aerobic output, and notes the data on straightforward endurance measures like VO2max is mixed and limited^[4].

In short, creatine looks like a muscle and power supplement first, with any endurance benefit being modest, situational, and not well established.

• Red meat, particularly beef
• Pork
• Poultry, in smaller amounts
• Fish, including salmon and herring
• Creatine monohydrate powder, the most studied supplement form^[11]

Vegans and vegetarians tend to have lower baseline muscle creatine stores since plant foods contain little to none, which may make supplementation more noticeably effective for this group^[3].

Most research protocols use a maintenance dose of about 3 to 5 g of creatine monohydrate per day^[9][10].

Some studies use a loading phase of around 20 g per day, split into smaller doses, for 5 to 7 days before dropping to a maintenance dose^[11].

Loading speeds up how quickly muscle creatine stores saturate, but is not strictly necessary. Consistent daily dosing over several weeks reaches similar saturation without it^[9].

Timing relative to workouts appears to matter less than total daily consistency, according to current reviews^[10].

Creatine monohydrate is considered one of the most extensively studied and safest supplements available in sports nutrition^[11].

The International Society of Sports Nutrition's position stand concludes that short and long term use, including at higher doses in clinical and athletic populations, has not shown consistent evidence of harm to healthy kidneys or liver function^[11].

• Mild water retention is common, especially during a loading phase^[9]
• Some people report minor digestive discomfort at higher single doses^[10]
• People with pre existing kidney disease should be cautious given limited data in that population^[11]
• Research in children and adolescents exists but is more limited, and use in this group is typically discussed with a clinician^[7]

• Resistance trainers looking to support lean mass and strength gains^[1][5]
• Older adults aiming to preserve muscle alongside strength training^[8][12]
• Vegans and vegetarians, who may start with lower muscle creatine stores^[3]
• Athletes in sports involving repeated sprints or bursts of power^[4]

People primarily chasing aerobic endurance gains, like distance runners focused on VO2max, should temper expectations given the weak and inconsistent evidence in that specific area^[4].

Creatine's case for building and preserving lean body mass is about as solid as supplement evidence gets, backed by randomized trials and meta-analyses across ages and training backgrounds^{[1][5][6][8][12]}.

Its case for boosting aerobic measures like VO2max remains thin and should not be the main reason someone tries it^[4].