What is the best way to train for a marathon?

Subscribe to enjoy similar stories. For many would-be marathoners, January seems as good a time as any to dust off their trainers and begin the journey to running 26.2 miles (42km). To hit a goal time or even just complete the race without injury, runners need to follow a training plan.

Running ability depends on three main factors, each partly genetic but all amenable to training. The first is the lactate threshold: the point at which lactate builds up in the blood faster than it is cleared away. The threshold marks the highest intensity at which the body can meet energy demands aerobically before it starts to rely more heavily on less efficient pathways.

The second factor is VO₂ max, the maximum rate at which the body can deliver and use oxygen during exercise. Both of these can improve quickly with training. The third factor is how much energy a person expends to cover a given distance in a given time.

This depends on both body shape and technique, and tends to change more slowly. There have been no high-quality randomised controlled trials comparing the effectiveness of different marathon-training plans, but analysis of large datasets of active runners can provide insights. One study, published in 2024 by researchers based across Britain, Ireland and New Zealand, analysed 16 weeks of training data from roughly 120,000 marathon runners who logged their runs on Strava, an exercise-tracking app.

Their main finding was that distance matters during training. The fastest marathoners—those finishing in less than two-and-a-half hours—covered roughly three times as many kilometres per week as the slowest. The number of long runs completed and the number of days spent training were also correlated with faster times.