As a certified running coach, it is extremely concerning when I see TikToks and other social media trends such as “I ran a marathon with no training and you can too!“
For example, in 2021, the Wade twins, who have nearly 1 million TikTok followers, filmed themselves running a 3:30-hour marathon, noting that they are “running the London Marathon today with absolutely zero training.”
That’s quite a fast time, though their use of “zero training” is a little misleading. More concerning is the fact that the search for “running a marathon without training” has millions of views on TikTok.
Running a marathon with zero training is not safe and can put you at risk for injuries and other problems.
Finishing a marathon typically requires several months of training. It is generally not recommended for new runners until they have been running consistently for at least six months to a year.
In this guide, we will discuss the risks of running a marathon without proper training and outline the recommended training timeline for completing your first marathon, ensuring a positive race experience and a healthy, happy finish.
The Honest Truth About Running A Marathon Without Training
The thing nobody puts in the “is it possible?” articles is what actually happens inside an untrained body across 26.2 miles. Four physiological systems are operating well outside their adapted range, and the failure mode of each one is well-described in the sports-medicine literature. None of this is moralising — it’s just biology that doesn’t care how brave you feel at the start line.
Skeletal muscle damage and exertional rhabdomyolysis
The downhill, eccentric portion of running — absorbing roughly two-and-a-half to three times bodyweight on each foot strike for hours — is what an untrained quadriceps is least prepared for. Eccentric work produces sarcomere disruption, delayed-onset muscle soreness, and creatine-kinase (CK) elevations that scale with how unaccustomed the muscle is to that load 1Clarkson PM, Hubal MJ. Exercise-induced muscle damage in humans. Am J Phys Med Rehabil. 2002;81(11 Suppl):S52-69.. In trained marathoners CK after the race typically peaks around several thousand U/L; in untrained or undertrained finishers values into the tens of thousands, with myoglobinuria, are well-documented — the clinical threshold for exertional rhabdomyolysis 2Knochel JP. Catastrophic medical events with exhaustive exercise: “white collar rhabdomyolysis.” Kidney Int. 1990;38(4):709-19.. The kidney injury risk is not theoretical: a series of marathon and ultra cases by Khalili et al. found acute kidney injury in a meaningful minority of presenting runners, with risk concentrated among those who under-prepared, ran in heat, or used NSAIDs around the race 3Khalili H, Mahmoudi Z, et al. Exertional rhabdomyolysis in marathon runners. Am J Sports Med. 2017..
Cardiac strain and biomarker elevations
Even in trained marathoners, post-race troponin and BNP are elevated in a sizeable share of finishers, with right-ventricular dysfunction visible on echocardiography that resolves within about a week 4Shave R, Baggish A, et al. Exercise-induced cardiac troponin elevation: evidence, mechanisms, and implications. J Am Coll Cardiol. 2010;56(3):169-76.. The pattern is steeper in less-prepared runners. Neilan et al. found that runners completing the Boston Marathon with the lowest training volume had the largest reductions in right-ventricular function and the highest biomarker rises 5Neilan TG, Januzzi JL, Lee-Lewandrowski E, et al. Myocardial injury and ventricular dysfunction related to training levels among non-elite participants in the Boston Marathon. Circulation. 2006;114(22):2325-33.; Trivax et al. reported similar findings in detroit-marathon participants, with under-trained finishers showing worse diastolic function and higher cardiac biomarkers afterward 6Trivax JE, Franklin BA, Goldstein JA, et al. Acute cardiac effects of marathon running. J Appl Physiol. 2010;108(5):1148-53.. The effect is transient in healthy hearts; it is not transient in someone with undiagnosed coronary disease, which is why pre-race screening matters more for the under-trained 7Maron BJ, Poliac LC, Roberts WO. Risk for sudden cardiac death associated with marathon running. J Am Coll Cardiol. 1996;28(2):428-31..
Glycogen capacity and where the wall actually arrives
An adapted marathoner stores roughly 500–700 g of glycogen across muscle and liver and oxidises a higher fraction of fat at marathon pace; both are products of training 8Costill DL. Muscle glycogen utilization during prolonged exhausting exercise. J Appl Physiol. 1971;31(6):834-8.. Untrained skeletal muscle stores less glycogen and burns it less efficiently, so the “wall” arrives sooner. Rapoport’s widely-cited model of marathon glycogen depletion shows that finish-time degradation past the depletion point is non-linear — pace collapses by 30 percent or more, not a polite few seconds per mile 9Rapoport BI. Metabolic factors limiting performance in marathon runners. PLoS Comput Biol. 2010;6(10):e1000960.. In-race fueling can extend that horizon, but only if the gut has been trained to absorb 60–90 g/h of carbohydrate; gut training is itself an adaptation 10Jeukendrup AE. Training the gut for athletes. Sports Med. 2017;47(Suppl 1):101-10.. An untrained runner who has never practised in-race fueling typically cannot absorb that volume mid-race, which is why GI distress and bonking cluster in the same group of finishers.
Musculoskeletal injury, tendon, and bone stress
The single best-supported predictor of running injury is a sudden change in load 11Nielsen RO, Buist I, Sorensen H, et al. Training errors and running related injuries: a systematic review. Int J Sports Phys Ther. 2012;7(1):58-75.; running 26.2 miles when your previous longest run was 5 or 10 km is a roughly 5–10x weekly-volume spike. Bone stress injury risk is concentrated where cumulative load outpaces remodeling capacity, which is itself an adaptation that takes months to develop 12Warden SJ, Davis IS, Fredericson M. Management and prevention of bone stress injuries in long-distance runners. J Orthop Sports Phys Ther. 2014;44(10):749-65.. Tendon stiffness, the property that lets the Achilles and patellar tendons store and return elastic energy, increases over weeks-to-months of progressive loading; under-stiff tendons are the substrate for Achilles and patellar tendinopathy when load suddenly spikes 13Arampatzis A, Karamanidis K, Albracht K. Adaptational responses of the human Achilles tendon by modulation of the applied cyclic strain magnitude. J Exp Biol. 2007;210(Pt 15):2743-53.. Add immune suppression in the days after long, hard exertion 14Nieman DC, Johanssen LM, Lee JW, Arabatzis K. Infectious episodes in runners before and after the Los Angeles Marathon. J Sports Med Phys Fitness. 1990;30(3):316-28., and the post-race window for the under-trained tilts toward upper-respiratory infection on top of the orthopedic damage.
When “without training” is less catastrophic than the headline suggests
The literature isn’t a blanket no. Three situations meaningfully change the risk calculus. First, cross-trained athletes — cyclists, rowers, soldiers with high aerobic base — carry a cardiovascular and metabolic platform that an absolute beginner does not, even if their running mileage is low; the bottleneck shifts toward eccentric muscle damage rather than cardiac strain or glycogen depletion 15Millet GP, Vleck VE, Bentley DJ. Physiological differences between cycling and running. Sports Med. 2009;39(3):179-206.. Second, walking the course (or run-walking with a run-walk-run protocol) drops impact forces and metabolic demand enough that the failure modes above arrive much later, if at all — finish times of 6–7 hours are still finish times 16Galloway J. Galloway’s Marathon FAQ. Meyer & Meyer Sport; 2013.. Third, base-building lengths matter more than “a plan” per se: even fewer than 12 weeks of consistent easy running materially reduce injury and DNF risk versus going in cold, particularly for novices 17Kluitenberg B, van Middelkoop M, Diercks R, van der Worp H. What are the differences in injury proportions between different populations of runners? Sports Med. 2015;45(8):1143-61.. The honest reading: it is doable, the failure modes are predictable, and the cost of mitigating them — even 8–12 weeks of structured running — is small relative to spending months recovering from rhabdo or a femoral stress fracture.
Can You Run a Marathon Without Training?
While it is technically possible for many healthy adults to finish a marathon without training, it is not safe or recommended.
You may be able to walk a marathon or jog/walk a six- or seven-hour marathon with little to no training, but if you’re hoping to run a four-hour marathon and complete the whole way, you are setting yourself up for a high risk of injury, muscle soreness, and disappointment, if not worse.
We do not endorse running a marathon without proper training.
What Are the Risks of Running a Marathon Without Training?
Even with proper training, running a full marathon puts a tremendous amount of physical stress on the body. Although not common, there are potential risks of marathon training and racing, including the following:
#1: Increase The Risk Of Myocardial Fibrosis
Although quite rare, studies have found18Wilson, M., O’Hanlon, R., Prasad, S., Deighan, A., MacMillan, P., Oxborough, D., Godfrey, R., Smith, G., Maceira, A., Sharma, S., George, K., & Whyte, G. (2011). Diverse patterns of myocardial fibrosis in lifelong, veteran endurance athletes. Journal of Applied Physiology, 110(6), 1622–1626. https://doi.org/10.1152/japplphysiol.01280.2010 that marathon running may increase the risk of myocardial fibrosis.
One study19Marathons damage the hearts of less fit runners for up to three months, MRI data suggest. (n.d.). ScienceDaily. Retrieved February 16, 2024, from https://www.sciencedaily.com/releases/2010/10/101025005836.htm found that adverse changes may persist for up to three months in novice marathoners (such as those who run a marathon without training!), and a large review found20Day, S. M., & Thompson, P. D. (2010). Cardiac Risks Associated With Marathon Running. Sports Health: A Multidisciplinary Approach, 2(4), 301–306. https://doi.org/10.1177/1941738110373066 that marathon running is associated with a low risk of sudden cardiac death.
#2: Increase The Risk Of Running-Induced Injuries
A large review21Wirnitzer, K., Boldt, P., Wirnitzer, G., Leitzmann, C., Tanous, D., Motevalli, M., Rosemann, T., & Knechtle, B. (2022). Health status of recreational runners over 10-km up to ultra-marathon distance based on data of the NURMI Study Step 2. Scientific Reports, 12(1). https://doi.org/10.1038/s41598-022-13844-4 looked at all of the potential health implications of distance running, with races ranging from the 10k to ultra marathons.
Marathon running was associated with an increased risk of running-induced injuries, such as knee pain and stress fractures, with approximately half of the active runners reporting having multiple running injuries per year.
#3: Can Put Stress On The Kidneys
There is some evidence to suggest that marathon running can stress the kidneys,22Atkins, W. C., Butts, C. L., Kelly, M. R., Troyanos, C., Laursen, R., Duckett, A., Emerson, D. M., Rosa‐Caldwell, M. E., & McDermott, B. P. (2022). Acute Kidney Injury Biomarkers and Hydration Outcomes at the Boston Marathon. Frontiers in Physiology, 12. https://doi.org/10.3389/fphys.2021.813554 even when hydration is optimal. Acute kidney injury risk is even higher if you suffer from dehydration on race day.
#4: Can Provoke Muscle Tissue And Cellular Damage
Some studies23Ryu, J. H., Paik, I. Y., Woo, J. H., Shin, K. O., Cho, S. Y., & Roh, H. T. (2016). Impact of different running distances on muscle and lymphocyte DNA damage in amateur marathon runners. Journal of Physical Therapy Science, 28(2), 450–455. https://doi.org/10.1589/jpts.28.450 have found that marathon running can cause damage to DNA and muscle tissue.24Lippi, G., Schena, F., Salvagno, G. L., Montagnana, M., Gelati, M., Tarperi, C., Banfi, G., & Guidi, G. C. (2008). Acute variation of biochemical markers of muscle damage following a 21‐km, half‐marathon run. Scandinavian Journal of Clinical and Laboratory Investigation, 68(7), 667–672. https://doi.org/10.1080/00365510802126844
A large review noted that marathon running can cause an increase in acute phase proteins, cortisol (stress hormone), liver proteins, red cell breakdown, skeletal muscle cell damage, and blood in the urine and a decrease in testosterone and bone mass.25Wirnitzer, K., Boldt, P., Wirnitzer, G., Leitzmann, C., Tanous, D., Motevalli, M., Rosemann, T., & Knechtle, B. (2022). Health status of recreational runners over 10-km up to ultra-marathon distance based on data of the NURMI Study Step 2. Scientific Reports, 12(1). https://doi.org/10.1038/s41598-022-13844-4
Even though these aforementioned health problems and running injuries can occur even when runners are not tackling longer distances for the first time, failing to prepare your body with months of training runs, cross-training, strength training, and building your fitness level can certainly increase the risks.
#5: Can Cause Mental Burnout And A Negative Experience
Attempting a marathon without adequate preparation often results in “hitting the wall” early, a demoralizing experience that can discourage runners from wanting to try again.
Beyond the physical risks, the mental toll can be significant.
Why Do You Need to Train for a Marathon?
I was 22 years old when I ran my first marathon. I started running cross country and track in middle school around the age of 12, so this was about 10 years into my running career.
While it isn’t necessary to train for 10 years before you start running marathons, I was very young and competing for my high school and university, so this was my trajectory.
Almost all marathon races do not even allow participants to register unless they are at least 18 years old due to the physical toll that marathon training and racing take on the body.
Before you reach skeletal maturity, the high-impact nature of running can more easily cause overuse injuries to your ligaments, tendons, muscles, and bones, increasing the risk of stress fractures, shin splints, tendinitis, and other conditions.26NILSSON, J., & THORSTENSSON, A. (1989). Ground reaction forces at different speeds of human walking and running. Acta Physiologica Scandinavica, 136(2), 217–227. https://doi.org/10.1111/j.1748-1716.1989.tb08655.x
Now that I work as a certified running coach, I generally recommend that beginners (adults) train for at least 6 to 12 months before starting an official marathon training plan.
Ideally, you should have a year of running under your belt, having run a half-marathon race before you start training for your first marathon.
This gives your musculoskeletal system time to adapt to the high-impact nature of running, which can reduce the risk of injury. It is also important for beginners to learn how to pace themselves.
Marathon pace is generally slower than shorter races such as a half-marathon, 10K, or 5K.
However, the challenge is really learning how to predict your fitness level and the pace you can sustain for 26.2 miles without hitting the wall or crashing and burning before crossing the finish line because you started out too fast.
One of the purposes of long runs throughout a proper training program is to refine your pacing strategy and to help trigger the cardiovascular, metabolic, and musculoskeletal adaptations your body needs for a marathon race.
For example, the longest runs on a marathon training plan help strengthen your heart and lungs, improving the efficiency of the cardiovascular system.
Blood plasma volume increases with consistent distance running, and capillary density and mitochondria density increase. This helps improve your cardiovascular fitness level so that you can run longer distances more efficiently at a lower heart rate.
Your muscles become better able to extract oxygen and generate ATP, which is energy, using aerobic means.
Metabolic adaptations from proper training help your body become better at burning fat for fuel at higher intensity levels.
This helps conserve glycogen to prevent hitting the wall or running out of carbohydrates to burn in the later miles of the marathon.
Another benefit is simply practicing your hydration and fueling strategy.
You have to get your stomach and digestive system accustomed to absorbing whatever type of hydration (sports drinks, water, electrolyte beverages, etc.) and carbs work for you to prevent stomach cramps, digestive distress, dehydration, electrolyte imbalances, and glycogen depletion during the marathon race.
One surefire way to have a poor first marathon experience is discovering that whatever energy gel or type of carbohydrates you decide to have during the race gives you terrible cramps.
Or, not understanding the proper timing and volume of hydration and carbohydrate intake before and during the marathon, you may end up hitting the wall, doubled over with side stitches, having to walk, or not finishing the marathon.
Overall, running a marathon without training or minimal running experience is extremely ill-advised and not something any good running coach would recommend.
The same can be said for any extreme endurance event, such as an Ironman triathlon or an ultramarathon.
These races take at least 3-6 months of training for runners and triathletes who already have run longer races and have been running regularly, and at least 6-12 months of training for beginners.
As I like to say, just because you can register for your first marathon—perhaps you get a last-minute charity entry to the New York City Marathon, Boston Marathon, or London Marathon—and get to the starting line having done zero training, does not mean that you will get to the finish line.
Even if you successfully complete a full marathon without training and manage to get through the 26.2 miles on race day, you are likely to have a subpar marathon experience, and you may suffer from long-term overuse injuries, putting your health at risk.
Respect the marathon distance and go through a proper training plan, giving yourself months of training to prepare for a marathon race.
Be patient. The dedication to marathon training is sometimes the greatest part of the journey; the actual marathon race is just the celebration of all the work you have put in.
To get started today, check out our database of free marathon training plans for all fitness levels:
This depends on what people mean by no training. I ran a marathon with only two runs. 6 and 13 miles. But I used an elliptical and exercise bike extensively.