Creatine is one of the few supplements that deserves more attention than its marketing often gives it.

It is usually associated with strength training, muscle gain and gym culture. That reputation is not wrong. Creatine monohydrate has one of the strongest evidence bases in sports nutrition, particularly for strength, lean mass and repeated high-intensity effort. The International Society of Sports Nutrition describes it as the most effective nutritional supplement currently available for increasing high-intensity exercise capacity and lean body mass during training [1].

But creatine is more interesting than “a supplement for people who lift weights”. It is involved in how our cells manage energy, especially when demand rises quickly. That makes it relevant not only to strength and power, but also to endurance training, ageing, cognition and recovery.

My own interest in creatine started through endurance sport. As a recreational ultra runner, I had assumed it was mainly useful for strength athletes. The more I read, the more that view seemed too narrow. Endurance events are not just steady aerobic output. They involve hills, surges, strength work, fatigue resistance, recovery between sessions and still being able to move well when tired. Later, during recovery from long COVID, I became more interested in the wider research around creatine, brain energy metabolism, fatigue and rebuilding capacity.

This is where creatine is worth understanding properly: as a cheap, well-studied and biologically plausible supplement that may be useful for more people than its reputation suggests.

What creatine actually does

Creatine is made naturally in the body and is also found in foods such as meat and seafood. Most of it is stored in skeletal muscle, with smaller amounts in the brain. In supplement form, the best-studied version is creatine monohydrate [2].

Its main role is in the creatine-phosphocreatine system, which helps regenerate ATP, the body’s immediate energy currency. This matters when energy demand rises quickly, such as during sprinting, lifting, climbing, repeated hard efforts or the more intense parts of endurance training [1].

That mechanism also explains why researchers are interested in creatine beyond sport. Muscle and brain tissue both rely heavily on energy availability. Creatine is not a random wellness trend. It has a clear physiological role.

Why endurance athletes may care

Creatine does not reliably improve every type of endurance performance, and it is not simply a way to make someone faster over a steady long-distance time trial. The evidence is more nuanced than that.

A 2023 review on creatine and endurance performance found that time-trial results are mixed, but creatine appears more useful in performances involving repeated surges in intensity or end spurts [3].

In real life, that is often where races are decided: climbs, accelerations, technical sections, sprint finishes or simply being able to respond when the pace changes.

For ultra runners and other endurance athletes, creatine is probably best thought of less as a direct “endurance booster” and more as a tool that may support the harder, more muscular parts of training: hills, gym work, intervals, recovery between sessions and maintaining strength under fatigue.

Muscle matters beyond sport

The strongest evidence for creatine is still in strength, lean mass and repeated high-intensity effort. That matters far beyond athletes.

Muscle is not just about appearance. It is important for metabolic health, balance, injury prevention, bone loading, independence and ageing well. As we get older, maintaining strength becomes one of the most practical forms of health insurance we have.

This is where creatine becomes particularly relevant. A 2017 meta-analysis found that creatine supplementation during resistance training increased lean tissue mass and upper and lower body strength in older adults [4]. A more recent 2025 systematic review and meta-analysis included 482 participants across eight trials, all with a mean age of at least 50, and found that creatine combined with resistance training improved lower limb strength and lean tissue mass [5].

The key phrase is “combined with resistance training”. Creatine seems to work best when the body is also being given a reason to adapt. A 2021 review of 20 studies in older adults with a mean age over 50 found that creatine plus resistance training increased lean tissue mass by about 1.2-1.3 kg more than placebo plus resistance training [6]. The same review noted that creatine taken only on resistance training days also significantly improved lean tissue mass and strength compared with placebo [6].

That is a useful reality check. Creatine is not a passive muscle-building supplement. It may help people get more from the strengthening work they are already doing. This is why it should not be seen only as something for young gym-goers. It may be especially relevant as we age, when preserving muscle and strength becomes harder but more important for everyday function, recovery after illness or injury, and maintaining independence.

What about cognition?

Creatine is also being studied for its possible cognitive effects. The brain uses a lot of energy, and creatine plays a role in brain energy metabolism, so this is biologically plausible.

A 2024 systematic review and meta-analysis found that creatine monohydrate may have beneficial effects on cognitive function in adults, particularly memory, attention time and information processing speed [7]. The authors were clear that larger and more robust studies are still needed.

This does not mean creatine should be marketed as a guaranteed brain fog fix. But the cognition research is interesting, especially for groups where creatine stores or brain energy availability may be more relevant: older adults, vegetarians or vegans, people under high training load, people with poor sleep, or people recovering from illness.

For older adults, the potential relevance is broader than sport. Preserving strength, maintaining independence and supporting cognitive function are all closely linked to quality of life. The evidence for muscle is stronger than the evidence for cognition, but both are worth watching.

Fatigue, chronic fatigue and long COVID

Fatigue is complicated, and long COVID is not one single problem. It can involve post-exertional symptom exacerbation, autonomic dysfunction, sleep disruption, inflammation, breathlessness, pain, cognitive symptoms and deconditioning.

Creatine is being studied in this area because of its role in energy metabolism. A 2026 randomised pilot trial in people with post-COVID condition found that 6 g/day of creatine was associated with improvements in fatigue and peripheral muscle strength over four weeks, with a favourable safety profile [8].

An earlier six-month placebo-controlled study in post-COVID fatigue syndrome also reported improvements in tissue bioenergetics and several patient-reported symptoms, including fatigue and concentration-related symptoms [9].

These studies are promising rather than definitive. For someone dealing with fatigue, reduced strength, poor recovery or cognitive symptoms, creatine may be a reasonable supplement to consider as part of a wider recovery plan. It should sit alongside pacing, nutrition, sleep, rehabilitation and appropriate medical care.

How to take it

For most people, the simplest option is still the best one: creatine monohydrate, 3-5g daily. You do not need a fancy version. Creatine monohydrate is the form with the strongest evidence, and newer or more expensive forms have not clearly shown superior benefits [1].

A loading phase, such as 20 g/day for five to seven days, can saturate muscle stores faster, but it is not essential. It may also cause more bloating or stomach upset. A steady daily dose is usually easier and more tolerable.

Powder is normally the best value. It can be mixed into water, yoghurt, smoothies or juice. It also works surprisingly well in hot drinks. Plain creatine monohydrate dissolves nicely in tea or coffee and usually does not noticeably change the taste. That makes it easier to take consistently, which matters more than perfect timing.

It is sensible not to mix creatine into a drink and leave it sitting around for days, because creatine can degrade in liquid over time depending on temperature, pH and duration. But mixing it and drinking it soon afterwards is practical [1].

Capsules are convenient, especially for travel, but several may be needed to reach an effective dose. Gummies are convenient too, and for some people that matters, but they are usually much more expensive per gram of creatine. They are not necessarily better. They are usually just easier to take. If choosing gummies, check the actual creatine dose per serving.

Downsides and cautions

The most common downside is a small increase in body weight, usually from water rather than fat. Creatine increases water held in muscle, which is part of how it works [1]. For runners or anyone sensitive to the number on the scale, that can be frustrating, but it is not the same as gaining body fat.

Some people experience bloating, nausea or loose stools, especially with higher doses or loading phases. A smaller daily dose, taken with food, is often better tolerated.

Creatine is generally considered safe for healthy adults at standard doses. A 2025 systematic review and meta-analysis found no significant adverse effect on glomerular filtration rate, although creatine can cause a modest rise in serum creatinine [10]. This matters because creatinine is used in blood tests to estimate kidney function. A rise in creatinine while taking creatine does not automatically mean kidney damage, but it can make blood test interpretation more complicated.

People with known kidney disease, reduced kidney function, abnormal kidney blood tests, or those taking medications that may affect the kidneys should seek medical advice before using creatine. Medical advice is also appropriate for people who are pregnant or breastfeeding, under 18, or living with complex medical conditions.

As with any supplement, creatine should be considered in the context of an individual’s health, medications, diet and goals.

Where creatine fits

Creatine is not essential for everyone, but it is one of the few supplements genuinely worth knowing about.

The strongest evidence is for strength, lean mass and repeated high-intensity exercise. The endurance evidence is more specific, but still relevant to hills, surges, intervals, strength work and recovery. The evidence around cognition and fatigue is earlier, but biologically plausible and increasingly interesting.

For someone training regularly, rebuilding strength, ageing and trying to preserve muscle, eating little meat or fish, or recovering from a period of illness, creatine may be worth considering.

Not because it does everything. Because it may support some of the systems that help us train, recover, think and function better.

To find out more click the links below:

• Unflavoured 100% Creatine Monohydrate
• Berry Flavoured Creatine Monohydrate

About the author

Dr Aleksandra Cygan, founder of Locum Lodge NZ, is a New Zealand-based doctor, GP trainee and recreational ultra runner. Her interest in creatine started through endurance training and became more focused after reading more about creatine’s potential role in muscle, cognition, ageing and fatigue.

This article is for general educational information only and is not a substitute for personalised medical advice. Anyone considering creatine supplementation, particularly those with medical conditions, abnormal kidney blood tests, pregnancy, breastfeeding, or regular medications, should discuss it with their doctor, pharmacist or another qualified health professional.

References

1. Kreider RB, Kalman DS, Antonio J, et al. International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine. Journal of the International Society of Sports Nutrition. 2017. Open access. https://pmc.ncbi.nlm.nih.gov/articles/PMC5469049/
2. Mayo Clinic. Creatine. Overview of creatine, dietary sources and safety considerations. https://www.mayoclinic.org/drugs-supplements-creatine/art-20347591
3. Forbes SC, Candow DG, Ostojic SM, et al. Creatine supplementation and endurance performance: surges and sprints to win the race. 2023. Open access. https://pmc.ncbi.nlm.nih.gov/articles/PMC10132248/
4. Chilibeck PD, Kaviani M, Candow DG, Zello GA. Effect of creatine supplementation during resistance training on lean tissue mass and muscular strength in older adults: a meta-analysis. Open Access Journal of Sports Medicine. 2017. Open access. https://pmc.ncbi.nlm.nih.gov/articles/PMC5679696/
5. Liu SC, Yang X, et al. The impact of creatine supplementation associated with resistance training on muscular strength and lean tissue mass in the aged: a systematic review and meta-analysis. European Review of Aging and Physical Activity. 2025. Open access. https://link.springer.com/article/10.1186/s11556-025-00392-9
6. Forbes SC, Candow DG, Ostojic SM, Roberts MD, Chilibeck PD. Meta-analysis examining the importance of creatine ingestion strategies on lean tissue mass and strength in older adults. Nutrients. 2021. Open access. https://www.mdpi.com/2072-6643/13/6/1912
7. Xu C, Bi S, Zhang W, Luo L. The effects of creatine supplementation on cognitive function in adults: a systematic review and meta-analysis. Frontiers in Nutrition. 2024. Open access. https://pmc.ncbi.nlm.nih.gov/articles/PMC11275561/
8. Santos MSC, et al. Creatine supplementation on fatigue related to post-COVID condition: a pilot study. Frontiers in Nutrition. 2026. Open access. https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2026.1731306/full
9. Slankamenac J, et al. Effects of six-month creatine supplementation on patient- and clinician-reported outcomes, tissue creatine levels and brain creatine levels in post-COVID-19 fatigue syndrome. 2023. Open access. https://pmc.ncbi.nlm.nih.gov/articles/PMC10630839/
10. Creatine supplementation and kidney function: systematic review and meta-analysis assessing serum creatinine and glomerular filtration rate. 2025. Open access. https://www.mdpi.com/2072-6643/17/6/1081