Should Endurance Athletes Take Creatine?
Dosing, Timing & the Weight Gain Question

Creatine has a branding problem. For most people it lives in the gym supplement aisle alongside protein powders and pre-workouts, squarely positioned as something for people trying to get bigger. The endurance athlete instinct is to walk straight past it.

That instinct is partly right and partly wrong. The research is nuanced — creatine genuinely helps in some contexts for endurance athletes and genuinely doesn’t in others. Here’s what the evidence actually shows.

What creatine does

Creatine is a naturally occurring compound synthesised in your liver, kidneys, and pancreas from three amino acids: arginine, glycine, and methionine. You also get small amounts from red meat, seafood, and poultry — but not enough to saturate muscle stores through diet alone.

Inside muscle cells, creatine combines with phosphate to form phosphocreatine (PCr) — the fastest energy currency your muscles have. When you need explosive power in a sprint, an attack, or a hill surge, phosphocreatine is the system that fires first. It’s depleted in seconds, then replenished during recovery.

Supplementing with creatine increases the total pool of phosphocreatine available. More stored phosphocreatine means more capacity for repeated high-intensity efforts before fatigue sets in. This is why it works so clearly for strength athletes and sprint sports — and why its application to endurance is more conditional.

Does creatine help endurance athletes? Where the evidence is strong

The pattern is clear. Creatine helps endurance athletes specifically when the event or training demands repeated high-intensity efforts embedded within longer aerobic work. The classic scenarios:

• Cycling: Attacks, climbs, chasing breakaways, sprint finishes. A 2025 study in Clinical Nutrition on trained cyclists confirmed creatine monohydrate improves sprint performance in cyclists.
• Triathlon: Transitions, bike surges, the run off the bike, the finish kick.
• Running: Parkrun surges, race finishes, track sessions, hill repeats during training.
• Strength training component: Most endurance athletes do some resistance training. Creatine’s benefit here is well-established regardless of sport.

Where the evidence is weak

For pure, steady-state aerobic endurance — a 3-hour marathon at even pace, a 120km ride at Z2 — the evidence for creatine improving performance is limited. A 28-day study on endurance-trained cyclists found that creatine supplementation increased resting muscle creatine and phosphocreatine but did not improve sprint performance at the end of endurance cycling exercise. VO₂ peak was unchanged.

This doesn’t mean creatine is useless for these athletes — it means the direct performance pathway is less clear. The indirect benefits (better strength training adaptations, faster recovery between hard sessions) may still apply.

Does creatine cause weight gain in runners?

This is the legitimate concern. Creatine is osmotically active — it draws water into muscle cells. Supplementation increases intracellular water retention, typically 0.5–1.5kg during a loading phase, less with gradual low-dose supplementation. For a weight-bearing sport like running, every extra kilogram costs running economy.

What the research shows about the weight gain:

• It is intracellular water retention, not subcutaneous bloating — the water is inside muscle cells, which is where you want it
• It is not fat mass — creatine has no effect on fat accumulation
• It attenuates significantly when using a gradual 3–5g/day protocol instead of a loading phase
• There is some evidence of improved thermoregulation in heat from the increased intracellular hydration — potentially beneficial for hot-weather running

The practical call: runners concerned about weight should skip the loading phase, take 3g/day consistently, and start during the offseason or Build phase — not in the 4–6 weeks before a target race.

Dosing protocols compared

Protocol	Dose	Time to saturation	Weight gain	Best for
Loading then maintenance	20g/day × 5–7 days, then 3–5g/day	~1 week	0.5–1.5kg acutely	Upcoming training block, cyclists
Low-dose continuous	3–5g/day from day one	~28 days	Minimal	Runners, long-term use
Middle ground	10g/day × 14 days	~2 weeks	Moderate	Balance of speed and tolerance

The key finding from Hultman et al. (1996) — still the definitive comparison — is that all three protocols reach the same final muscle creatine concentration. The endpoint is identical. Only the timeline differs. For endurance athletes who have time on their side and are weight-conscious, the low-dose continuous protocol is almost always the right choice.

When should endurance athletes start taking creatine?

This is where Kovr’s nutrition framework and creatine supplementation intersect directly. The Build mode — a small calorie surplus to support adaptation, best used in the offseason or before a training block — is the ideal window to begin creatine.

Here’s why the timing matters:

• You’re not racing, so the 0.5–1kg of initial water retention doesn’t affect race performance
• The strength training component of base-building is where creatine’s benefits are clearest
• By the time your training block ramps up and you transition to Maintain mode, your stores are fully saturated
• You arrive at race season with the phosphocreatine pool topped up for surges, kicks, and high-intensity intervals

Starting creatine two weeks before your A-race is the wrong approach. Starting it 8–12 weeks out during base training is the right one.

Best time of day to take creatine for runners and cyclists

The research is clear here: timing within the day has minimal effect on creatine’s effectiveness. The goal is muscle saturation over weeks, not an acute pre-workout spike. Consistency matters far more than when you take it.

Practical options that work equally well:

• With your post-run recovery meal (carbohydrates enhance creatine uptake — research suggests 100g carbs per 5g creatine improves retention)
• With breakfast
• Mixed into your protein shake after the hardest session of the day

What doesn’t matter: whether it’s pre or post workout, morning or evening, with food or without.

Which creatine supplement should endurance athletes buy?

Creatine monohydrate. Not creatine HCl, not creatine ethyl ester, not any of the dozens of proprietary blends that cost three times as much. Creatine monohydrate is the most researched form, the most bioavailable, and the cheapest. Virtually every study cited in this article used it.

For purity, look for NSF Sport, Informed-Sport, or HASTA certification. Creapure is the gold standard ingredient — a patented form of creatine monohydrate manufactured by AlzChem in Germany to pharmaceutical-grade standards. It’s notable for two things: exceptional purity (99.99% pure creatine monohydrate with virtually no contaminants or byproducts) and tolerability. Many athletes who experience GI discomfort on generic creatine find Creapure significantly easier to handle at higher doses — including during loading phases — because of the absence of impurities that can irritate the gut.

Creapure isn’t a brand you’ll necessarily see on the front of a product — it’s an ingredient that dozens of reputable supplement brands license and use. Look for the Creapure logo on the label or “made with Creapure” on the packaging. If a brand is using Creapure they’ll tell you, because it’s a genuine quality signal worth advertising. Buy plain powder — there’s no performance benefit to gummies, capsules, or flavoured formulations beyond convenience, and you pay a premium for the format.

The honest summary

Creatine is worth considering for endurance athletes who:

• Race in events with surges, attacks, or sprint finishes (triathlon, criteriums, track, parkrun)
• Do regular strength training as part of their programme
• Are in the offseason or Build phase where weight gain is less critical
• Cycle or swim more than they run (weight-bearing concern reduced)

It’s less compelling for pure steady-state marathon runners focused solely on race weight and aerobic efficiency — though even here the strength training adaptation argument applies.

If you do decide to take it: 3–5g of creatine monohydrate daily, consistently, starting in the offseason. Skip the loading phase if you’re a runner. Buy Creapure or equivalent with third-party certification. Give it 4 weeks before expecting any performance signal.