First Marathon How to train for your first marathon

How long should your long runs get?

Kathrine Switzer was a Syracuse University student when she told her coach, Arnie Briggs, a veteran of 15 Boston Marathons, that she wanted to run Boston. Briggs didn't buy it. "No dame ever ran no marathon," he told her, as Zwift's telling of the story recounts. Then he gave a little: "I believe you could, but you'd have to prove it to me." About three weeks before the race, the two ran 26 miles in practice. Switzer felt so good she suggested another 5-mile loop, to feel "extra confident." At the end of 31 miles, Briggs nearly passed out. Then he kept his word and took her to Boston.

You don't have to prove anything, and you don't have to run 26 miles before race day. For most first-timers, the long run tops out at about 20 miles, a few weeks before the race. Hal Higdon's Novice 1 builds its long run from 6 miles to 20, and so do most of the plans above. Lighter final weeks and race-day energy carry you the rest of the way.

That long run is the biggest change from the half, and it's the run that gets you ready: marathoners whose training includes longer long runs tend to finish faster, though the studies show a link, not proof. It also needs the most care. Your lungs will be ready for a longer Sunday before your legs are, and many running injuries start with one run that goes well past your longest of the past month. So good plans grow the long run a mile or two at a time and step back every few weeks: a shorter long run, a lighter week, then a new longest. Those lighter weeks matter, because training that piles up without a break is linked to more injuries and illness.

Run the long ones slowly, and take walk breaks if they help. At an easy pace, a 20-miler keeps you out for 3 hours or more, so it doubles as rehearsal: the shoes, the socks, and the gels or chews you'll carry on race day.

How much should you eat during marathon training?

For Shalane Flanagan, food became part of the training. "For me, running over 100 miles a week, food and fueling has become a focal point in my training," she told espnW in 2015. She writes cookbooks for runners with Elyse Kopecky, her best friend and nutritionist, and in 2017 she won the New York City Marathon, the first American to win the women's race in 40 years.

You won't be running 100 miles a week. But a first-marathon build changes your food needs too, and the long run changes them most. A 20-miler burns about 2,000 calories for a 150-pound runner, and a rest day burns almost nothing extra. Eat the same every day and you'll come up short on the days that count. Eating enough to match your training is what turns the miles into fitness, so let your food move with your week.

Eat more on the big days. Add carbs the day before and the day of a long run or a harder workout. The sports-nutrition guidelines scale the same way, from about 5 to 7 grams of carbs per kilogram a day for an hour of training to 6 to 10 for 1 to 3 hours.

Refill after long runs. Eat a real meal with carbs and protein soon after, within a couple of hours. The carbs refill your legs for the next run, and the protein starts the repair. Don't save calories for later. The rest of that day is when the long run turns into fitness.

Spread your protein out. Runners need more carbs and protein than people who don't train, and the protein guidelines suggest spreading it across the day, every 3 to 4 hours, with some at each meal rather than one big dinner.

Keep rest days normal. Your body does its rebuilding on rest days, so eat regular meals, just without the extra a long run adds.

What happens if you don’t eat enough?

Before the 2022 Boston Marathon, a team from Boston Children's Hospital surveyed 1,030 runners, from first-timers to elites, about their training, health, and eating, then matched the answers to race results. Runners with signs of underfueling finished slower than runners of similar size, experience, and training. "Runners with signs of chronic underfueling had much slower times on race day," said Kristin Whitney, who directs the hospital's Injured Runners Clinic, describing the study. They also needed medical help twice as often. More than half had no eating disorder or disordered eating. "Under-fueling is often unintentional," Whitney said.

It's easy to do by accident. Long training often dulls your appetite, the same page notes, so eating only when you're hungry can leave you short, especially after a long run.

You'll usually feel it before you see it. You're tired all the time, your legs never feel fresh, easy runs feel harder than they should, and your paces stop improving, because running short on fuel blunts what the training does for you. You catch every cold going around, since eating far less than you burn raises the risk of getting sick. And the one that ends a build: low energy weakens bone and raises the risk of a stress fracture. If two or three of these sound familiar, eat more on your running days first, and see a doctor or sports dietitian if they hang on.

Can you lose weight training for a marathon? Yes, slowly, if your food is part of the plan. The size of your calorie deficit is what drives fat loss, so take it from the day's food overall, never from your running days, and keep it gentle, about half a percent to one percent of your weight a week. That daily math is exactly what I built Buena Vida to do: log a 20-miler and that day's targets go up, with more carbs; take a rest day and they ease back.

How you’ll know the training is working

Bill Bowerman, the University of Oregon coach who co-founded the company that became Nike, gave every new class of runners the same lecture. "Take a primitive organism, say a freshman. Make it lift, or jump or run. Let it rest. What happens? A little miracle. It gets a little better," he said, in words his former runner Kenny Moore put in his biography. "Stress. Recover. Improve. You'd think any damn fool could do it. But you don't. You work too hard and rest too little and get hurt."

A marathon build is months of that cycle, and "recover" is the part people skip. When your plan hands you a lighter week, take it.

The "improve" part is easier to trust when you can see it. Around week 8, pull up an easy run from week 1 and compare. Same pace, lower heart rate? That's your fitness showing up, and an Apple Watch is accurate enough to show it. The record catches the other half of Bowerman's warning, too: working too hard and resting too little. A long run that jumped too far. A week with more miles and less food. A small ache that keeps coming back between runs, which early evidence suggests can come before a bigger injury. A pair of shoes quietly past its miles. Each is easy to miss when your runs, your food, and your plan live in three different places.

The taper and race day

Boston, April 1967. About 2 miles in, race co-director Jock Semple grabbed at Kathrine Switzer, yelling "Get the hell out of my race and give me those numbers!" Her boyfriend knocked him aside, and Switzer made up her mind. "I'm going to finish this race on my hands and knees if I have to," she recalled. She finished in about 4 hours and 20 minutes.

Your training will carry you, too. Before race day, the last 2 to 3 weeks of your plan get lighter on purpose, because running about half as much in the final weeks, while keeping a little speed, helps you race better. Running less can feel strange. Let it. Keep eating normal meals, with extra carbs in the last 2 days.

On the morning, start slower than feels right. Walk through the aid stations if it helps (Higdon recommends it). Save the brave miles for the last 10K.

Higdon has one more line on his Novice 1 page worth carrying to the start: "As far as I'm concerned, there is no such thing as 'too slow.'" The hardest step was the one you've already taken. You decided to go.