Training & Fitness - Running & endurance
How to train for a marathon
Last updated 29 September 2026. How we write this .
Marathon preparation builds on a consistent running base, using recoverable mileage, gradual long runs, appropriate faster work and a taper. Pacing, recovery and race-day familiarity matter.
Start here Marathon preparation builds on a consistent running base, using recoverable mileage, gradual long runs, appropriate faster work and a taper. Pacing, recovery and race-day familiarity matter.
By the end, you will understand A running base comes before the plan What marathon preparation changes Build a week that can be repeated Where this information comes from Claim-cited evidence. Central research claims on this lesson are linked to specific studies or official guidance.
This lesson links the specific studies and guidance used for its central claims.
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Training for a marathon means building the capacity to sustain running over 42.195 kilometres while managing fatigue, energy demands and repeated impact. The foundation is consistent, mostly easy running, supported by gradually developed long runs, appropriate faster work, strength training and recovery. A taper reduces accumulated fatigue before the race, while realistic pacing and familiarity with equipment and race-day demands help translate preparation into performance.
A running base comes before the plan
Someone beginning from no running needs a beginner running phase before marathon-specific preparation. A marathon plan assumes that regular running is already tolerable and repeatable. The lesson on Couch to 5K covers that earlier stage; completing one short event does not automatically establish readiness for the training load of a marathon.
A useful base is demonstrated through recent consistency, rather than a single impressive run. Relevant questions include whether ordinary runs leave manageable fatigue, whether running fits alongside sleep and work, and whether the runner can sustain their current routine without recurring interruptions. There is no universally validated mileage threshold that certifies readiness.
The same programme will not suit a first-time finisher and an experienced runner pursuing a faster time. Run-walk approaches can also be part of marathon preparation, but walking breaks do not remove the demands of covering the full distance. The available preparation time must fit the starting point.
What marathon preparation changes
Repeated endurance exercise encourages adaptations in the systems that deliver and use oxygen. Muscle develops greater capacity to produce energy aerobically, including changes in mitochondria, the structures where much of this energy production occurs. These adaptations help make a sustainable pace less demanding relative to the runner's capacity.
Running economy is the energy required to maintain a given speed. Marathon performance depends partly on economy, partly on aerobic capacity, and partly on how much of that capacity remains sustainable as fatigue develops. Being fast over a short distance therefore does not guarantee that the same runner can sustain an ambitious marathon pace.
Bones, tendons and muscles also need to tolerate repeated loading. Feeling less breathless does not prove that these tissues are ready for a large increase in distance. Preparation builds both fitness and tolerance of prolonged running, which is why cardiovascular fitness from another sport does not fully substitute for running experience.
Build a week that can be repeated
The major parts of marathon preparation serve different purposes. Their value depends on how they fit together, rather than on completing each component as aggressively as possible:
Mostly easy running builds accumulated endurance work at a fatigue cost that allows consistency. A gradually developed long run provides exposure to prolonged effort and its practical demands. Selected marathon-pace or threshold work adds specificity for established runners with sufficient recovery capacity. Strength work develops force capacity without overwhelming recovery from running. Recovery periods and a taper allow adaptations to emerge while accumulated fatigue falls. Easy running should make up the main volume because repeatedly running hard limits how much training can be recovered from. The separate lessons on easy running and threshold training explain those intensities. Here, the key judgement is whether harder work supports the overall week or repeatedly disrupts it.
Training load includes duration, intensity, hills, terrain and frequency. Increasing several together can create a much larger change than the mileage alone suggests. A fixed weekly percentage increase is not a proven injury-prevention rule, and missed sessions do not create a debt that must be repaid through compressed training.
Long runs develop endurance, not certainty
Long runs expose the runner to sustained muscular work, accumulating fatigue and the challenge of keeping effort controlled. Their duration develops gradually within the wider programme. A long run that repeatedly compromises the following days may undermine consistency despite looking impressive in a training log.
There is no single longest-run distance that guarantees readiness. Distance and time on feet describe different aspects of load: the same route can involve substantially more exposure for a slower runner. Covering the full marathon distance in training is not a prerequisite, and a rehearsal race can carry a considerable recovery cost.
For established runners, selected running near a realistic marathon pace can develop familiarity with the intended effort. Threshold work can support aerobic performance, but it is more demanding and does not need to appear in every session. A pace target should reflect current preparation, rather than forcing preparation to match an aspirational finishing time.
Observational studies associate training characteristics such as greater running volume with marathon performance. They cannot establish that adding distance will benefit every runner: experience, ability and the capacity to remain healthy influence both training volume and race results.
Strength and recovery support the running
Strength training can improve the ability to generate force and may reduce the energy cost of running. Small controlled studies in distance runners support improvements in running economy, although methods and participants vary. This evidence is stronger for performance-related adaptations than for a claim that strength work prevents all running injuries.
Strength sessions also create fatigue. During marathon preparation, their usefulness depends on whether they support the running workload. Introducing unusually demanding strength work alongside a major increase in running makes it harder to identify which load is causing difficulty.
Recovery includes sufficient sleep and enough overall dietary energy to support both training and normal body functions. Persistent fatigue, declining performance and repeated disruptions are reasons to reconsider the workload, not proof that more determination is needed. A single wearable score cannot reliably distinguish productive training fatigue from every other cause of feeling unwell.
This framework assumes an adult with an established running base. Pregnancy, medical conditions, recent injury or persistent symptoms change the context and require individual assessment. Chest pain, fainting, severe breathlessness, neurological symptoms or significant or worsening pain warrant stopping exercise and seeking appropriate clinical help.
Understand equipment, energy and fluid demands
Familiarity with shoes and clothing matters because small areas of rubbing or discomfort can become consequential over prolonged running. Equipment is best judged through its behaviour during relevant training, rather than novelty, price or another runner's experience. A shoe cannot compensate for an unsuitable training load.
Carbohydrate stored as glycogen supports prolonged exercise, and limited availability can contribute to a marked slowing of pace. Controlled endurance studies support the role of carbohydrate availability in performance, but the familiar 'wall' has several possible contributors, including early pacing, muscular fatigue and environmental stress. It is not simply a failure of motivation.
Training also provides a context for understanding digestive tolerance and the practicalities of fluids and carbohydrate before race day. This is distinct from prescribing amounts or schedules. Fluid needs vary with conditions and individual losses; neither ignoring fluid demands nor assuming that more is always better is a sound general principle.
Tapering and pacing reveal the preparation
A taper reduces training load before competition so that accumulated fatigue falls while established fitness is largely retained. Small controlled endurance studies support this principle, although the best arrangement for every recreational marathon runner is not established. Familiar running can remain, while total work decreases; last-minute overload is unlikely to rescue missing preparation.
Starting faster than a sustainable pace raises the physiological cost early, including greater reliance on carbohydrate and earlier fatigue. The time apparently gained can be lost later. Race excitement and a comfortable opening kilometre are weak evidence that the planned pace was too cautious.
Heat increases the challenge of losing body heat and can raise cardiovascular strain at the same running speed. Hills and wind also change the relationship between pace and effort. Race-day judgement therefore includes adjusting expectations to conditions, rather than treating a watch prediction as a requirement.
Judge claims by outcomes and evidence
Marathon preparation combines established exercise physiology, controlled studies of specific training methods, observational runner data and coaching judgement. Evidence for broad principles is stronger than evidence for one universally optimal calendar. Studies often involve small samples or experienced runners, which limits direct application to beginners.
When assessing a plan, ask who it was designed for, what running base it assumes, how it handles interruptions and whether its claims concern fitness, finishing time or injury risk. Those are different outcomes. A successful athlete's routine is an example, not proof; the most useful programme is one whose demands remain compatible with sustained preparation.
This lesson is general education, not an individual training, nutrition or medical prescription. Adapt activity to your experience and health, and seek qualified advice for symptoms, injury, pregnancy or a medical condition.
Related in this classroom Related in other classrooms The studies behind this page An evaluation of the training determinants of marathon performance: a meta-analysis with meta-regression - Journal of Science and Medicine in Sport, 2020The association between running injuries and training parameters: a systematic review - Journal of Athletic Training, 2022Sources for this classroom
Educational content only. Not medical advice, diagnosis or treatment. Always consult a qualified healthcare professional before changing your health regimen.