Creatine Monohydrate
Also known as: Creatine, Creatine Monohydrate, CrM, Creapure, Methyl Guanidine-Acetic Acid
Phosphocreatine Precursor | Most-Researched Sports Supplement
Overview
Creatine is a naturally occurring nitrogenous organic acid synthesised endogenously from glycine, arginine, and methionine in the liver, kidneys, and pancreas, with the remainder obtained from animal-source foods (meat and fish supply ~1 g per pound). Approximately 95% of the body's creatine pool resides in skeletal muscle, where it exists predominantly as phosphocreatine — the rapid-turnover phosphate donor that regenerates ATP during high-intensity, short-duration efforts. Supplementation with 3-5 g of creatine monohydrate daily increases muscle creatine content by 10-40% above baseline (depending on starting levels and diet) and is the single most-researched ergogenic aid in sports nutrition, with hundreds of randomised controlled trials supporting its safety and efficacy. The International Society of Sports Nutrition's 2017 position stand and the NIH Office of Dietary Supplements both recognise creatine monohydrate as the most effective nutritional supplement currently available for increasing high-intensity exercise capacity and lean body mass. Beyond performance, growing evidence supports cognitive benefits in sleep-deprived states, neuroprotective effects in conditions like traumatic brain injury, and potential roles in healthy ageing.
Key benefits
- Increased phosphocreatine stores extending high-intensity work capacity by ~10-15%
- Lean body mass gains of 1-2 kg over the first 4-12 weeks (combined fluid + muscle)
- Strength gains 5-15% greater than placebo when paired with resistance training
- Improved sprint and repeated-effort performance (intervals, team sports)
- Cognitive benefits in sleep-deprived or cognitively-stressed conditions
- Neuroprotection in animal models of TBI, stroke, and neurodegenerative disease
- Bone-density preservation in older adults when combined with resistance training
- Negligible cost (~£15 for a 6-month supply of monohydrate)
Mechanism of action
Creatine functions through the ATP-PCr (phosphocreatine) energy system, which provides the immediate, high-power energy substrate for short-duration, high-intensity efforts (1-10 seconds). At rest, phosphocreatine donates its phosphate group to ADP via the creatine kinase reaction (PCr + ADP ⇌ ATP + Cr), regenerating ATP without requiring oxygen or glycolytic flux. Higher muscle phosphocreatine content extends the duration over which maximal-effort work can be sustained before glycolysis becomes rate-limiting, which is why creatine supplementation most reliably improves performance in sets of 1-12 reps, sprint repeats, and similar repeated-effort modalities. Beyond bioenergetics, creatine acts as an osmolyte that draws water into the muscle cell, increasing intracellular hydration and mechanical signalling for protein synthesis. Animal models also show creatine supplementation upregulates mTORC1 signalling, satellite cell activation, and IGF-1 expression in working muscle. In the brain, creatine is taken up via SLC6A8 (creatine transporter); supplementation modestly raises brain phosphocreatine levels, with cognitive benefits most evident under metabolic stress (sleep deprivation, hypoxia, age-related decline). Creatine is also a CNS-active neuroprotective agent through reduction of oxidative stress and apoptotic signalling.
Molecular data
- Type
- Methylguanidinoacetic acid (C4H9N3O2)
- Half-life
- ~3 hours (plasma); muscle saturation reached over 4 weeks at maintenance dose
Indications
What the research community uses this compound for, with self-reported effectiveness.
Performance
Strength & Power Output
Most effectiveMost consistent benefit — meta-analyses (Lanhers 2015, Wax 2021) show 5-15% greater strength gains over 6-12 weeks of resistance training versus placebo, with the effect concentrated in the upper body and in trained lifters. Mechanism: increased phosphocreatine availability sustains maximal-effort sets longer and supports greater training volume.
Lean Body Mass
Most effective1-2 kg of additional lean mass over 4-12 weeks compared to placebo, partly from intracellular fluid retention and partly from greater training-induced hypertrophy. Effect is reproducible across age groups, sexes, and training experience.
Sprint & Repeated-Effort Performance
EffectiveImprovements in repeated-sprint protocols (e.g. 6×35m) and high-intensity interval performance, particularly when recovery between efforts is short. Less consistent benefit in single-effort sprints under 10 seconds where existing PCr stores aren't yet depleted.
Cognition
Sleep-Deprived Cognitive Performance
ModerateClinical trials (McMorris 2007, Cook 2011) show creatine attenuates decrements in working memory, reaction time, and mood when subjects are sleep-deprived. Doses of 5-10 g/day for several weeks before the stressor are typical.
Age-Related Cognitive Decline
Under researchEmerging evidence in older adults suggests creatine improves memory performance, particularly in vegetarian or vegan populations with low baseline creatine intake. Effects are smaller and less consistent than in performance contexts.
Recovery & Tissue Repair
Muscle Damage & Soreness
ModerateModest reductions in markers of exercise-induced muscle damage (creatine kinase, soreness) when supplementation begins before high-volume training. Effect is small but reproducible.
Sarcopenia / Healthy Ageing
EffectiveCombined with resistance training in adults over 60, creatine produces greater gains in lean mass, strength, and bone mineral density than training alone. Useful in fall-prevention and healthspan-extension protocols.
Neurological
Traumatic Brain Injury (Adjunct)
Under researchSmall clinical trials in paediatric TBI suggest faster recovery of cognitive function with creatine supplementation in the post-injury period. Larger trials needed; mechanism is plausibly bioenergetic — restoring brain phosphocreatine after injury-induced ATP depletion.
Dosing protocols
Common protocols by delivery method. Adjust the curve below to model accumulation in your own cycle.
Oral
Bioavailability: ~99% for monohydrate; lower for ethyl ester due to first-pass conversion to creatinineTake with carbohydrate or insulin-spiking meal for marginally faster muscle saturation, or alone with water — long-term outcomes are equivalent.
| Protocol | Dose | Frequency | Route / duration |
|---|---|---|---|
| Maintenance (most common) Reaches full muscle saturation in 3-4 weeks. No loading phase required. | 3-5 g | Once daily | Indefinite |
| Loading + Maintenance Faster saturation (≈1 week vs 3-4 weeks). GI upset is more common during loading. | 20 g/day for 5-7 days, then 3-5 g/day | 4×5 g doses spread across the day during loading | 5-7 days loading, then ongoing maintenance |
Interactions
Pairwise interactions with other compounds you might be cycling — the same data behind the cycle builder's safety check.
Caffeine
MonitorOlder studies suggested caffeine blunted creatine's ergogenic effect, but more recent work (Trexler 2016) finds no meaningful interaction at typical doses. Most pre-workout formulas combine the two without issue.
Beta-Alanine
SynergisticBeta-alanine extends performance in the 30-90 second domain (intramuscular carnosine buffer) while creatine extends the 1-10 second domain. The two operate on distinct energy systems and are commonly stacked.
HMG-CoA Reductase Inhibitors (statins)
CompatibleNo clinically significant interaction. Statin-induced muscle symptoms are unrelated to creatine pathways.
Safety
Reported adverse effects, contraindications, and what to monitor on cycle.
Common side effects
- Initial water-weight gain of 0.5-2 kg in the first 1-2 weeks (intracellular fluid)
- Mild bloating or GI upset, especially during a loading phase
- Increased thirst
Uncommon side effects
- Diarrhoea or stomach cramps with single doses >10 g
- Muscle cramps (anecdotal; not consistently shown in controlled trials)
Rare side effects
- Asymptomatic elevation of serum creatinine (a metabolite of creatine — does NOT indicate kidney impairment but can confuse routine bloodwork)
Contraindications
- Pre-existing renal disease (relative contraindication — large studies show no harm in healthy kidneys, but caution in CKD)
Monitoring
- If routine bloodwork shows elevated creatinine, mention creatine supplementation to your clinician — they can order cystatin C as a kidney-function marker that isn't affected by creatine intake.
References
Primary literature and clinical-trial data informing this entry.
Kreider RB et al. International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation. J Int Soc Sports Nutr. 2017;14:18.
Comprehensive position stand — the canonical reference.
Lanhers C et al. Creatine supplementation and lower limb strength performance: a systematic review and meta-analyses. Sports Med. 2015;45(9):1285-94.
Meta-analysis of strength outcomes.
Forbes SC et al. Creatine supplementation for older adults: focus on sarcopenia, osteoporosis, frailty and cachexia. Bone. 2022;162:116467.
Healthy-ageing review.
NIH Office of Dietary Supplements — Creatine. Health professional fact sheet.
Public-domain summary of dosing, evidence, and safety.
Last updated . How this page was sourced is described in the methodology.