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
Cognition
Recovery & Tissue Repair
Neurological
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 | Duration |
|---|---|---|---|
| Maintenance (most common) | 3-5 g | Once daily | Indefinite |
| Loading + Maintenance | 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 |
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.