Creatine is the most studied performance supplement in history. Over 500 peer-reviewed studies. Endorsed by the International Society of Sports Nutrition. Used by millions of athletes worldwide.

And yet, if you’re an endurance athlete — a runner, cyclist, triathlete, or rower — you’ve probably been told it’s “not for you.” That it’s for bodybuilders. That it’ll make you slow and bloated.

That narrative is outdated, and the science has moved on.

This guide cuts through the noise. We’ll show you exactly what creatine does inside an endurance athlete’s body, which benefits are real, which risks are overblown, and how to make a smart, individualized decision for your own training and racing.

1. What Creatine Actually Is (and Why It Matters for Endurance)

Creatine is a naturally occurring compound synthesized in your liver and kidneys from the amino acids arginine, glycine, and methionine. You also get small amounts from meat and fish — roughly 1–2 grams per day if you’re omnivorous, essentially none if you eat plant-based.

About 95% of your body’s creatine lives in your muscles as phosphocreatine (PCr). Its primary job: rapidly regenerate adenosine triphosphate (ATP) — the currency your muscles spend during every contraction.

Here’s the mechanism that matters for endurance athletes: during high-intensity efforts — a steep climb, a race-finishing sprint, a threshold interval — ATP depletes fast. Phosphocreatine donates its phosphate group to “recharge” ADP back into ATP in milliseconds, before your aerobic system can catch up.

Supplemental creatine monohydrate increases total creatine and phosphocreatine concentrations in skeletal muscle by approximately 20–40%, increasing the capacity to regenerate ATP during high-intensity exercise.

— Kreider et al., International Society of Sports Nutrition Position Stand, 2017

The Energy System Overlap

A common mistake is thinking endurance athletes operate purely on aerobic metabolism. In reality, every surge in pace, every hill, every kick pulls on your phosphocreatine system. A triathlete executing 20 hill repeats, a runner hitting 400m intervals, a cyclist attacking on a climb — all of them are repeatedly burning through phosphocreatine stores. Having more available means sustaining higher quality for longer.

2. Seven Proven Benefits for Endurance Athletes

Benefit 1: More Power Output — Even in Endurance Sports

A 2019 study of well-trained triathletes demonstrated that creatine supplementation significantly increased cycling power output during the bike leg of a triathlon. Power is pace. More watts at a given effort level means faster split times, period. With fuller phosphocreatine reserves, athletes can sustain higher intensity for longer before fatiguing.

Benefit 2: Superior High-Intensity Repeat Performance

The ISSN Position Stand is explicit: creatine supplementation consistently improves performance in repeated bouts of high-intensity, short-duration exercise. For an endurance athlete, this means interval sessions feel less brutal — and quality doesn’t drop as sharply across a long set. If you typically complete 8 quality 800m intervals before form breaks down, creatine could let you complete 10. Over a 16-week training block, that accumulated quality work is enormous.

Benefit 3: Faster Recovery Between Sessions

Multiple studies confirm creatine reduces exercise-induced muscle damage and accelerates recovery. For endurance athletes stacking back-to-back hard days — a hallmark of effective training — this means arriving at tomorrow’s session less depleted. The benefits of creatine in recovery have been demonstrated multiple times, including in resistance-trained athletes whose muscle physiology translates directly.

Benefit 4: Cognitive Edge During Long Events

This one surprises people. The brain consumes enormous amounts of ATP, and phosphocreatine serves the same ATP-regeneration role in neural tissue as it does in muscle. A double-blind crossover trial published in the Proceedings of the Royal Society found creatine supplementation improved working memory and intelligence test scores. A 2023 review confirmed improvements in cognition and memory under metabolic stress — exactly the conditions present in hour 8 of an Ironman.

Benefit 5: Improved Hydration and Thermoregulation

You’ve heard creatine causes dehydration. The evidence says the opposite. A 2021 systematic review in the Journal of the International Society of Sports Nutrition found no support for the dehydration or cramping hypothesis. Multiple studies show athletes supplementing with creatine demonstrate improved blood plasma volume, lower heart rates during exercise in the heat, and reduced rectal temperatures compared to placebo groups. For endurance athletes competing in hot conditions, this is a meaningful potential advantage.

Benefit 6: Injury Reduction

Creatine supplementation is associated with reduced muscle strains, tightness, and overall soft tissue injuries. One study of football players found those taking creatine had less cramping, less dehydration, and fewer heat-related illnesses. For athletes pushing high training volumes, even a modest reduction in injuries compounds into significantly more quality training weeks per year.

Benefit 7: Long-Term Health and Longevity

Beyond performance, creatine has a growing evidence base for systemic health benefits: preservation of lean muscle mass with aging, bone health, cardiovascular markers, and neuroprotection. Given that most endurance athletes are in sport for life — not just for the podium — these long-term benefits strengthen the case regardless of whether the pure performance data is fully definitive for your event.

3. Real Risks vs. Myths — What the Evidence Actually Says

Myth: Creatine Damages Your Kidneys

This is the most persistent myth in sports nutrition. It originates from a misunderstanding: creatine metabolism produces creatinine, a waste product that kidney function tests measure. Elevated creatinine doesn’t mean damaged kidneys — it means your creatine turnover is higher, which is expected. Multiple long-term safety studies, including systematic reviews by the ISSN, conclude that creatine at recommended doses poses no risk to renal function in healthy individuals. Caveat: if you have pre-existing kidney disease, consult your physician first.

Myth: Creatine Causes Cramping and Dehydration

As a 2021 ISSN review stated bluntly, experimental and clinical research does not validate the cramping or dehydration hypothesis. The evidence trends in the opposite direction. The myth likely persists because athletes associate any supplement with risk — not because data supports it.

Real Risk: Gastrointestinal Distress

Some athletes — not all — experience bloating, stomach upset, or loose stools, particularly at higher doses. This is the most common genuine side effect. It’s largely avoidable by skipping the loading phase, taking 5g with food rather than on an empty stomach, ensuring the powder is fully dissolved before drinking, and choosing a high-purity form.

Real Risk: Fluid Retention and Weight Gain

Creatine draws water into muscle cells. This is not fat. But it is real, and it matters for weight-sensitive athletes. Without a loading phase, the gain is typically 0.5–1.5 kg and stabilizes within 2–4 weeks. See the dedicated section below for race strategy around this.

4. How to Take Creatine: Dosing, Timing & Form

Timing: Does It Matter?

Not much. Some research suggests a small advantage to post-workout timing, but the effect size is minor. What matters far more is consistency. Pick a time that makes it a reliable habit — with your morning coffee, with a post-ride recovery shake, with dinner. Specific timing is secondary to daily adherence.

Which Form to Buy

Creatine monohydrate is the gold standard. Don’t be upsold on fancy alternatives (creatine HCl, buffered creatine, ethyl ester) — they are more expensive and not demonstrably superior in outcome studies. Look for products certified by NSF Certified for Sport, Informed Sport, or HASTA. The brand Creapure (a German manufacturer) is widely regarded as a benchmark for purity.

5. Who Benefits Most — and Who May Not

Who Is Less Likely to Benefit?

Approximately 25–30% of people are classified as “non-responders” — their muscles already have near-maximal creatine stores. This is partly genetic and partly diet-related (high red meat consumers). Elite athletes with years of high-volume training may also see smaller performance bumps. A 2023 systematic review of elite endurance athletes found no significant improvement in performance measures — though four of thirteen studies did show gains in lactate threshold and time-to-exhaustion.

6. The Weight Gain Question Answered

Weight is a loaded topic in endurance sports. A heavier body demands more oxygen per kilometer. VO₂max is expressed relative to body weight. So the water retention associated with creatine deserves an honest conversation.

Without a loading protocol, most endurance athletes gain 0.5–1.5 kg, primarily in the first 1–2 weeks, primarily intramuscular water. After that, weight stabilizes. Over months, if creatine enables better training adaptation, the improvement in power-to-weight ratio can exceed the cost of the water weight.

7. Does Creatine Hurt VO₂max?

A 2021 systematic review found a negative correlation between creatine supplementation and VO₂max. This needs context before it alarms you.

VO₂max is measured in mL of oxygen per kilogram of body weight per minute. If you gain 1 kg of water weight, VO₂max calculated relative to body weight mathematically declines — even if your absolute oxygen consumption is unchanged or improved. This is a measurement artifact, not a physiological impairment.

The authors explicitly acknowledged significant methodological limitations: inadequate randomization, only three of nineteen studies properly assessing VO₂max, and wide variability in participant training status. The practical takeaway: creatine probably doesn’t impair your aerobic engine. It may temporarily affect your weight-relative metric. Monitor your own data if this is a concern.

8. Creatine & Drug Testing

Creatine monohydrate is not a banned substance under WADA or any major sporting federation. However, supplement manufacturing contamination is a genuine risk in competitive sport — banned substances can inadvertently end up in products produced on shared equipment.

This has resulted in real athlete sanctions. Protect yourself: only purchase products certified by NSF Certified for Sport, Informed Sport, or HASTA. These programs conduct batch testing and provide important protection under anti-doping rules.

9. Should You Take It? A Decision Framework

There is no universal answer. But here is a clear framework to make the decision for yourself:

Take creatine if: you do any training involving intervals, surges, or repeated high-intensity efforts; you train more than 4 days per week; you’re plant-based or eat minimal red meat; you’re over 35; you want cognitive benefits during long races; or you’re willing to experiment for 8–12 weeks and measure the impact.

Be cautious or skip if: you have pre-existing kidney disease (consult your doctor); you’re in peak race season and every gram of weight is critical; you experience significant GI distress that can’t be managed with protocol adjustments; or you’re an elite athlete already at peak training adaptation with limited margin for improvement.

10. Frequently Asked Questions