A Beginner’s Guide to Training for a Full Marathon

A first marathon is built on 4 or 5 months of steady, mostly easy training, and the main threat to it is injury. Novice runners are injured at a rate of about 17.8 injuries per 1,000 hours of running, according to a 2015 meta-analysis, compared with 7.7 for established recreational runners. A beginner who runs 4 hours a week for 18 weeks logs 72 hours, which at the novice rate works out to about 1.3 injuries on average.

Base Fitness Before Week 1

Most beginner plans are 16 to 20 weeks long and assume the runner can already complete 3 or 4 easy runs a week without pain. A runner who cannot yet do that should spend 6 to 8 weeks building to it before day 1 of the plan. The marathon plan then adds distance to an existing habit, and the body has had time to adapt tendons and bones to the impact of regular running.

Run-walk intervals are a legitimate way to build that base. They lower the load on each session while keeping total time on feet high. A common pattern is 4 minutes of running followed by 1 minute of walking, repeated for the length of the session, with 1 minute added to each running block every week or two.

Easy Pace and Weekly Structure

Most training time should be easy. In a 10-week study of 30 recreational runners, a group that did 77% of its training at low intensity improved its 10K time from 39 minutes 18 seconds to 37 minutes 19 seconds. A threshold-focused group with the same amount of hard running improved from 39:24 to 38:00. The low-intensity group gained more, though the study did not find a statistically reliable difference between the two.

For a beginner, easy pace is a pace at which full sentences are possible. A typical week has 4 runs. Three are easy, one of them is the long run, and the fourth includes a short block of faster running such as 4 to 6 repeats of 3 minutes at a hard effort. Two days are for rest or cross-training such as cycling or swimming.

Long Run Progression

In a study of 441 recreational marathon runners, those whose longest training run was under 21 kilometers, about 13 miles, ran slower marathons. Weekly volume under 40 kilometers, about 25 miles, was also tied to slower finishing times, while runners averaging more than 65 kilometers a week finished faster. Higher volume and longer long runs were not linked to a higher injury risk.

Most plans build the long run by 1 or 2 miles at a time and peak at 18 to 20 miles about 3 weeks before race day. Every third or fourth week, the long run is a few miles shorter so the body can adjust before the next increase. Long runs are done at easy pace, often 60 to 90 seconds per mile slower than goal marathon pace.

Fluids on Long Runs

Long runs of 2 hours or more are the first sessions where fluid becomes a planning problem. Exercise performance can suffer at a fluid deficit of about 2% of body mass, according to the National Athletic Trainers’ Association position statement on fluid replacement for the physically active. For a 160-pound runner, that is 3.2 pounds.

Routes without fountains require the runner to carry fluid. Handheld or waist-belt water bottles for running hold enough for an hour or two, and a hydration vest holds more for the longest runs. A loop route that passes the runner’s car or home every 4 or 5 miles is another option. Whatever system the runner uses, it should be tested on long runs well before race day, along with any fuel taken during those runs.

Mileage Increases and the 10% Rule

The 10% rule caps the weekly increase in mileage at 10%. In a randomized trial of 532 novice runners preparing for a 4-mile event, a 13-week graded training program based on the 10% rule produced an injury rate of 20.8%, against 20.3% for a standard 8-week program.

A larger study identified high-risk sessions by looking at single runs instead of weekly totals. It followed 5,205 runners in 87 countries, logged 588,071 running sessions over 18 months, and compared each run with the runner’s longest run in the previous 30 days. Runs 10% to 30% longer than that mark were tied to a 64% higher injury rate, and runs more than twice as long to a 128% higher rate. The authors also reported risk rising with single-run increases between 1% and 10%, which puts the 10% figure itself in question.

For a beginner, the long run should therefore grow from the longest recent run, by a mile or two, and never jump ahead of it. Pain that changes a runner’s stride, or that worsens as a run goes on, is a reason to stop and rest for several days.

Strength Training for Runners

Strength work has better evidence for injury prevention than stretching does. A 2014 meta-analysis of randomized trials on exercise interventions to prevent sports injuries found that strength training reduced sports injuries to less than one third, while stretching showed no protective effect. A beginner’s program can be 2 short sessions a week of squats, lunges, calf raises, and hip exercises. These sessions fit on easy days or after a short run. They should stop about 10 days before the race, so that no soreness from them reaches the start line.

Tune-Up Race and Goal Time

A half marathon 5 to 7 weeks before the marathon gives a beginner a real result to set goal pace from. The usual conversion is the Riegel formula, which for this distance multiplies the half marathon time by about 2.09. A 2-hour half marathon predicts a marathon of about 4 hours 10 minutes. The tune-up race also gives the runner one practice of race-morning routine, including breakfast timing and a crowded start.

A 2016 study of race times among recreational runners surveyed 2,303 runners and found the Riegel formula was well calibrated up to the half marathon but gave marathon times at least 10 minutes too fast for half of the runners. Typical weekly mileage was associated with race speed at every distance in the same data. A beginner on a modest weekly volume should set goal pace from a finish time 10 to 15 minutes slower than the formula gives and adjust in the second half of the race if the pace feels easy.

Questions for the Next 18 Weeks

Around week 9 to week 12, the long run reaches 15 or 16 miles, and a minor ache may show up for the first time. Cutting one long run short does not reset the 30-day maximum, so a runner can resume the plan the following week without creating a spike. Will the runner repeat a shorter week and rebuild from there, or run the scheduled distance to keep the plan on time?