HPC › Nutrition › Glossary
Creatine is a naturally occurring nitrogenous compound synthesised in the liver, kidneys, and pancreas from the amino acids arginine, glycine, and methionine. Stored primarily in skeletal muscle as phosphocreatine, it rapidly regenerates ATP during maximal exertion. Supplementation raises total muscle creatine by approximately 20 per cent, improving high-intensity performance and supporting brain energy under demand.
Often framed as a muscle supplement, creatine also maintains a phosphocreatine reserve in the brain, providing neuroenergetic support during cognitively demanding tasks.
How it works
Skeletal muscle stores approximately 95 per cent of the body's creatine pool, divided between phosphocreatine (roughly 60 per cent) and free creatine (roughly 40 per cent). During maximal muscular effort, creatine kinase catalyses the transfer of a phosphate group from phosphocreatine to ADP, regenerating adenosine triphosphate within five to eight seconds 1 2. This reaction bypasses oxidative phosphorylation entirely, making phosphocreatine the fastest available energy buffer for explosive contractions.
Oral supplementation saturates the muscle creatine pool above its baseline level. A loading phase of 20 g per day for five to seven days, or a slower approach of 3 to 5 g per day maintained over several weeks, raises total muscle creatine by roughly 20 per cent 1. Performing the loading phase alongside resistance exercise potentiates uptake in the exercised limb. A maintenance dose of 3 to 5 g per day sustains elevated stores.
The brain maintains its own phosphocreatine reserve, independent of the muscle pool. Creatine buffers neuronal ATP during cognitively demanding tasks and during sleep deprivation, when brain energy supply falls short of demand 3 4. This neuroenergetic role mirrors the muscular mechanism: the same phosphocreatine shuttle that sustains a sprint also supports cognitive output when the brain operates under load.
Example
An athlete on a structured training programme follows a five-day loading phase, then settles into 3 g daily. During sprint intervals, repeated bouts that would ordinarily degrade after the third set remain consistent through the fifth: the phosphocreatine pool resaturates between sets fast enough to sustain output. In the days following a heavy training block, cognitive tracking shows smaller performance dips than during the unloaded baseline period.
When the phosphocreatine pool stays topped up, the sprint and the decision that follows it both benefit.
Why it matters
For anyone whose performance depends on repeated high-intensity efforts, creatine is among the most reliably evidenced ergogenic aids available. The mechanism is direct: a larger phosphocreatine pool means more ATP regenerated per bout, more bouts sustained before fatigue sets in, and faster recovery between efforts. Those with the lowest baseline muscle creatine respond most strongly, which means vegetarians and vegans, who obtain no dietary creatine (the compound is found exclusively in animal-source foods), show the greatest performance and cognitive gains 2.
The cognitive evidence is age-sensitive. A meta-analysis of ten randomised controlled trials reported a small overall memory benefit (SMD = 0.29), a finding that has faced methodological scrutiny; the effect in adults aged 66 to 76 (SMD = 0.88) proved more robust 3, and a 2024 systematic review confirmed improvements in cognitive function and executive performance across healthy and clinical populations 4. Creatine monohydrate has been confirmed safe at doses up to 30 g per day for up to five years across populations ranging from infants to older adults 2.
What does creatine do in the body?+
Creatine is stored in skeletal muscle as phosphocreatine and in smaller amounts in the brain. During intense exercise, creatine kinase transfers a phosphate group from phosphocreatine to ADP, regenerating adenosine triphosphate within seconds. This sustains explosive output during maximal efforts lasting roughly five to fifteen seconds and accelerates recovery between repeated bouts.
Does creatine improve memory and cognitive function?+
The evidence is promising and age-sensitive. A meta-analysis of ten randomised trials found a small overall memory benefit (SMD = 0.29), with a much larger effect in adults aged 66 to 76 (SMD = 0.88). Cognitive benefits appear most pronounced when brain energy demand is elevated, such as during sleep deprivation or high cognitive load.
Is creatine safe for long-term use?+
Creatine monohydrate has one of the strongest safety records among sports supplements. Controlled trials confirm it is safe at doses up to 30 g per day for up to five years across diverse populations, from infants to older adults, with no adverse effects on kidney or liver function in healthy individuals.
Who benefits most from creatine supplementation?+
Those with the lowest baseline muscle creatine respond most strongly. Vegetarians and vegans, who consume no dietary creatine from food, tend to see the largest performance and cognitive gains. Older adults also show outsized cognitive benefits. Non-responders, whose muscle creatine is already near saturation, are more common among habitual meat-eaters.
