Training for Your First Marathon

Developing the capacity for sustained running

Endurance training produces adaptations in the delivery and use of oxygen, including changes in blood volume and in the working muscles’ capillary and mitochondrial density. Capillaries supply the muscle with blood; mitochondria use oxygen in the processes that regenerate ATP, the molecule that powers muscular contraction. Together, these adaptations help support sustained exercise. Joyner and Coyle, 2008

For a new marathon runner, that development is expressed through ordinary training: a comfortable run becomes longer, a familiar route takes less effort, and the weekly routine becomes easier to sustain. Progress should be judged across several weeks. An unusually good run or a difficult morning gives less information than the pattern of training around it.

We recommend choosing a plan whose opening weeks resemble the running already being completed. If the first week requires a substantial increase in distance, frequency and intensity, the plan has started too far ahead of the runner. A 16-week schedule can organise the final preparation for someone with an established running routine. Someone starting from very little running needs time to develop that routine before attempting the same progression.

Easy effort is a skill worth learning

Beginners often judge a run by the pace on their watch. During marathon preparation, the more useful question is whether the effort matches the purpose of the session. An easy run provides running volume at an intensity that leaves room for the rest of the week. It should feel distinct from a hard sustained effort.

Comfortable speech offers a practical guide. The talk test has been studied as a way of monitoring exercise intensity: the ability to speak comfortably generally corresponds to exercise below the ventilatory threshold used in those studies. Reed and Pipe, 2014 On an easy run, ordinary sentences should remain comfortable. If speaking becomes broken or strained, slow down.

This can require more restraint than expected, especially on hills or when running with someone faster. Walking breaks are a useful way to keep the effort manageable. If a run–walk approach is intended for race day, use it in training so the transitions and average pace are familiar.

At the start of a first-marathon block, there is little reason to make every run a test. We usually prioritise establishing regular easy running and a manageable long run before adding substantial interval work. That gives the runner a clearer sense of how much training is being tolerated and where additional work can fit.

Progression across the whole week

Training frequency and weekly distance are associated with marathon performance, but the same total can be organised in very different ways. Doherty et al., 2020 A week dominated by one long run offers a different pattern of exposure from a week with running distributed across several days.

For someone already comfortable running four times a week, a simple arrangement is three shorter easy runs and a longer weekend run, with rest days between selected sessions. As the long run extends, the shorter runs need to remain manageable. If an additional running day is introduced, begin with a short session rather than simultaneously extending every run.

There is no single percentage increase that guarantees injury-free training. In a randomised trial of novice runners preparing for a shorter event, a programme based on the familiar 10% progression rule did not reduce injuries compared with the standard programme. Buist et al., 2008 A percentage alone cannot account for previous training, intensity or an interruption caused by illness.

We therefore use the runner’s response to guide progression. Completing a week comfortably, recovering between runs and maintaining normal movement provide reasons to consider the next step. Persistent pain, a change in gait or repeatedly having to abandon sessions are reasons to review the programme. Repeating a manageable week is often the more useful training decision than advancing simply because the calendar says to.

Long runs measured in time as well as distance

The long run extends the amount of sustained running a beginner can manage and makes the race routine familiar. It also places the longest continuous demand of the week on the runner, so its duration deserves attention.

Consider a 28 km session. At 5:00/km it takes 2 hours 20 minutes; at 7:30/km it takes 3 hours 30 minutes. The distance is identical, but the time spent running differs by more than an hour. This is why copying another runner’s longest-run distance can be misleading. For a slower first-time marathoner, a duration limit may be more appropriate than pursuing a particular number of kilometres.

The evidence does not establish one longest run that every beginner must complete. We choose that session using the runner’s recent long runs, the rest of the weekly workload and the time available for recovery. Running the full 42.195 km in training is unnecessary for this approach, and reaching 20 miles is not a pass-or-fail test of readiness.

Long runs should also help settle practical decisions. Use the shoes and clothing intended for the race, practise breakfast timing and begin taking carbohydrate during the longer sessions. When a run goes well, note what was repeatable about it. When it goes poorly, consider pace, food, fluid, conditions and the previous days of training before changing the entire plan.

Eating enough to support the training

As running increases, the energy needed to support it rises. Problematic low energy availability occurs when too little dietary energy remains for normal physiological functions after exercise demands are accounted for. It can affect health and performance in both women and men, including bone health, reproductive function and recovery. Mountjoy et al., 2023

Marathon preparation is therefore a poor setting for an aggressive weight-loss target. Regular meals and additional food around longer sessions belong in the training plan. Persistent fatigue, recurrent injuries or menstrual disruption warrant appropriate assessment rather than an assumption that feeling depleted is a normal part of becoming a runner.

During longer runs, practise taking carbohydrate instead of saving gels for the race itself. Repeated practice can improve gastrointestinal tolerance and helps identify products and amounts that are manageable while running. Jeukendrup, 2017 Start with an intake that can be tolerated and develop the race strategy over the block. Our fuelling guide explains the hourly amounts and the calculations behind them.

Recovery also needs space in the diary. Place rest or easier running after demanding sessions, and account for work, travel and sleep when deciding whether the next increase is sensible. A programme needs to function within the runner’s life if it is going to be completed.

Turning preparation into a first race plan

The first marathon provides limited personal evidence about what happens in the later stages. That makes a controlled opening especially valuable. Choose a target using the training completed, then resist the temptation to reinterpret it after a fast first few kilometres. The pacing article explains how to combine recent race results with long-run experience.

The final weeks should reduce the training load. This taper allows accumulated fatigue to fall while maintaining some familiar running, and endurance research supports its use before competition. Wang et al., 2023 The longest sessions should already be complete; missed training is a reason to reassess the target rather than compress more work into race week.

A successful first preparation leaves the runner with a pace, breakfast and fuelling schedule that have all been considered before arriving at the start. For the 2027 event, the London Marathon guide places those decisions within the wider build-up and race logistics.