Creatine and Marathon Training: How to Use It Through a 16-Week Block
The most common question we get about creatine is not "does it work". It is "when do I start, and will it make me heavy on race day".
Fair question. This is a week-by-week guide to using creatine through a 16-week marathon block: when to start, what to expect on the scales, what happens in taper, and what to do on race morning.
First, the honest framing
Creatine will not directly make you faster over 26.2 miles. There is no evidence it improves VO2 max or running economy, and any brand telling you otherwise is overselling.
What it does is act on the things that build the marathon. The International Society of Sports Nutrition's position stand concluded that creatine enhances post-exercise recovery and helps athletes tolerate heavy training loads (Kreider et al., J Int Soc Sports Nutr, 2017). And a controlled trial with muscle biopsies found creatine plus carbohydrate produced greater muscle glycogen supercompensation than carbohydrate alone (Roberts et al., Amino Acids, 2016) — which is directly relevant to how a marathon is fuelled.
So: it improves your ability to complete the block, and it may improve how well you load for the race. Both matter more than most marginal gains.
Weeks 1–4: Base — start now, expect the scales to move
Dose: 5g a day, every day, including rest days.
Skip the loading phase. Twenty grams a day for a week saturates you faster, but it also front-loads the water gain and the GI upset into the exact period you are trying to build a routine. Steady 5g gets you fully saturated in three to four weeks with none of that.
What to expect: 1–2kg on the scales in the first two to three weeks. This is intracellular water — water drawn into the muscle cell, not bloat sitting under your skin. It is not fat, and it does not mean the block has started badly. Expect it, note it, move on.
Hydration: your cellular water demand has gone up. Drink to thirst and slightly beyond in the first fortnight, and pay attention to electrolytes rather than just fluid volume — drinking plain water in larger volumes without sodium is how runners end up diluting themselves.
This is exactly why our creatine sits inside a hydration formula. Daily Hydrate & Perform delivers 5g of creatine monohydrate alongside 500mg of sodium plus potassium and magnesium, so the fluid and electrolyte side is handled in the same scoop.
Weeks 5–10: Build — where the benefit shows up
This is the hardest part of a marathon block. Mileage is climbing, sessions are getting longer, and the long run is starting to cost you real recovery. It is also where the fourteenth week gets decided — not by heroics, but by whether you keep absorbing the work.
What creatine is doing here:
- Refilling glycogen faster between sessions. If your long run is Sunday and your threshold session is Tuesday, the speed of glycogen resynthesis is the thing that decides whether Tuesday goes well.
- Reducing post-run protein breakdown. A study of athletes running identical 60-minute endurance sessions before and after 15 days of creatine found lower post-exercise lactate and reduced markers of protein degradation, concluding that creatine tended to decrease muscle glycogen and protein degradation, especially after endurance exercise (Tang et al., Eur J Nutr, 2013).
- Making your strength work count. The two gym sessions a week you keep skipping are one of the best-evidenced injury-prevention tools available. Creatine's effect on strength training output is its most replicated finding.
- Supporting hill reps and threshold intervals. These are phosphocreatine-dependent efforts, whatever the total session distance.
Practical note: take it consistently. Creatine is not a pre-workout. There is no acute effect and no point timing it around a session. It works by being saturated.
Weeks 11–13: Peak — the heaviest weeks
Peak weeks are where runners break. The 20-milers, the marathon-pace long runs, the accumulated fatigue of ten weeks.
Two things to attend to:
Sodium. On long runs in warm weather you will lose meaningful sodium. Under-replacing it is one of the more common causes of feeling flat for two days after a long run. This is a hydration problem, not a creatine problem — a systematic review with meta-analysis found no evidence that creatine impairs heat tolerance or fluid balance (Lopez et al., J Athl Train, 2009) — but it is the problem that most often gets blamed on creatine.
Cognitive fatigue. Peak weeks are mentally heavy, and often slept through badly. Reviews of creatine and brain function report that the clearest cognitive effects appear precisely when the brain is stressed, including under sleep deprivation (Forbes et al., Nutrients, 2022).
Weeks 14–16: Taper and carb loading
Do not stop taking it. This is the most common mistake. Runners drop creatine in taper to "shed the water weight", and in doing so throw away the one place where creatine has a direct, measured benefit for a marathon: glycogen loading.
The Nottingham trial found that creatine augmented carbohydrate-mediated muscle glycogen supercompensation, with the effect visible within the first 24 hours of recovery and sustained across six days (Roberts et al., 2016). Carb loading is exactly this process, deliberately induced, in the three days before your race.
Being creatine-saturated when you carb load is the point. Dropping it a fortnight out defeats the purpose.
On the body-mass question: yes, you will be carrying 1–2kg more than you would be otherwise, and more again once you are glycogen-loaded (glycogen itself is stored with water). Every runner who carb loads accepts this trade already. The stored fuel is worth more than the mass.
Race week and race morning
- Keep taking your 5g daily through race week. Nothing changes.
- Do not introduce anything new. If you have not taken creatine before, race week is emphatically not the time to start — you will get water gain and possible GI upset with none of the training benefit.
- Race morning: take it as normal if it is part of your routine and you have practised it. If in doubt, do what you did before your best long run.
- Nothing on race day should be untested. The rule applies to creatine as it does to gels, shoes and breakfast.
After the race
Post-marathon recovery is where the muscle damage bill comes due. Keep taking creatine through the recovery weeks — the ISSN position stand notes its role in post-exercise recovery and in rehabilitation from injury (Kreider et al., 2017), and the fortnight after a marathon is when both matter.
The one-page summary
| Phase | Creatine | What to watch |
|---|---|---|
| Weeks 1–4 (Base) | Start 5g/day, no loading | 1–2kg water gain, hydration and electrolytes |
| Weeks 5–10 (Build) | 5g/day, every day | Session-to-session recovery, strength work quality |
| Weeks 11–13 (Peak) | 5g/day | Sodium losses on long runs, sleep and cognitive load |
| Weeks 14–16 (Taper) | 5g/day — do not stop | Carb loading works better saturated |
| Race day | As per your practised routine | Nothing new, ever |
| Recovery | 5g/day | Repair and getting back to running |
One scoop of Daily Hydrate & Perform covers the creatine and the electrolytes together — 5g creatine monohydrate, 5g L-glutamine, 500mg sodium plus potassium and magnesium, made in the UK and independently Cologne List® tested.
For the full marathon routine — daily vitamins, pre-run performance, joint support and overnight recovery — see the Marathon Race Ready Bundle.
Shop Daily Hydrate & Perform →
Further reading
- Cologne List® product database — search which supplements have been batch-tested for banned substances at the German Sport University Cologne.
- British Dietetic Association Food Fact Sheets — independent, dietitian-written guidance on nutrients and supplements.
- SENR Registrant Directory — find a registered sport and exercise nutritionist if you want individual advice.
References
- Kreider RB et al. J Int Soc Sports Nutr. 2017;14:18. https://doi.org/10.1186/s12970-017-0173-z
- Roberts PA et al. Amino Acids. 2016;48(8):1831–42. https://doi.org/10.1007/s00726-016-2252-x
- Tang FC et al. Eur J Nutr. 2014;53(1):61–71. https://doi.org/10.1007/s00394-013-0498-6
- Lopez RM et al. J Athl Train. 2009;44(2):215–23. https://doi.org/10.4085/1062-6050-44.2.215
- Forbes SC et al. Nutrients. 2022;14(5):921. https://doi.org/10.3390/nu14050921
Study references retrieved via PubMed. This article is for general information and is not medical advice. Food supplements are not a substitute for a varied diet and healthy lifestyle.