Why the Half Marathon is Booming

How the half marathon has become the go-to goal race among American runners

In recent years, the half marathon has become the preferred distance of recreational runners. In the past decade, participation in the half marathon has skyrocketed while marathon finisher numbers have flattened. In 2000, roughly a third more runners finished a half marathon (482,000) than the marathon (353,000). By 2014, nearly four times as many (2,046,600) runners finished a half than a full (550,600). Here are some of the reasons the 13.1-mile distance has been booming.

1. The half is a better first endurance race.

“When the marathon is your first race, the training is just too demanding,” says Jeff Gaudette, the head coach at RunnersConnect. “When people bite of more than they can chew, it turns them off from becoming a lifelong runner. For 95 percent of people who sign up for the marathon as their first event, with no significant training history, the race is just miserable.”

“You need to build up to the marathon,” McMillan says. “You have a higher likelihood of success if you have more running under your belt.” The half presents an inspiring goal that is simply more doable for most. When you’re training for the half, you can ramp up both weekly mileage and long runs more gradually, and reach an adequate level of training in the time frame most runners feel appropriate to dedicate to the race.

2. More people can get in adequate training to finish strong and healthy.

Regardless of how experienced you are, many of today’s runners don’t have the time, energy and ability to put in enough miles to run strong through the full marathon distance.  Take a common rule of thumb that the long run shouldn’t represent more than 25 percent of your weekly total. That means that any week you are running a 20-miler should total 80+ miles. That agrees with the range that a poll of coaches recommends to excel at the distance.

The surveyed coaches took care to point out that miles aren’t everything and experiences differ, but all came up with similar mileage totals for each level of success you should expect with that amount of training. Note that the same level of training that will barely get to the marathon finish line will likely let you run strong through the finish of a half.

Peak miles per week to
Distance Survive Finish Strong Excel
Full 25–30 40–50 55–80+
Half 15–20 25–30 40–70+

3. Runners are less likely to get injured in training or the race.

Research shows that spikes in training load are what predispose an athlete to injury. It isn’t doing too much as much as it is doing too much too soon. Runners get injured training for a marathon because they increase their load too quickly.  To build up to the weekly miles and long runs needed for the marathon without courting injury requires years of steady, consistent progress, which most people are unable or unwilling to commit to.

In contrast, the half is beyond today’s reach for many, but within their grasp with a few weeks of training. “You can get away with doing a 10 or 11 miler as your long run for the half marathon,” Gaudette says. “That is doable for more people in 4 to 6 months.”

If you don’t get injured training for a marathon, many get injured on race day, because they haven’t built the necessary base to handle it, making the race itself a huge spike in their usual load. Those who’s training puts them on the “survive” end of the spectrum end up very close to the limits of their ability, and any additional challenge, like a hot day, can put them over the edge.

The marathon is extreme, however, even for experienced, high mileage runners. On the days that things don’t go well, they often end up running several miles with compromised strides, inviting injury.  The half, while long enough to not be a sure thing, is more forgiving. “If it doesn’t go well it doesn’t mean you’re in a survival march,” McMillan says.

4. Racing half marathons is more conducive to development as a runner.

While the marathon inspires many to run more and to build endurance, it also often hinders runner’s development in at least two ways. First, the mandate of getting in more miles crowds out any other training like improving strength and mobility or even speed work. When you’re stretched to the limit just to keep up with the required volume, you don’t have the time or energy to do strides or squats after your run, and you’re afraid to put in an interval workout because you’re so beat up all the time.

“The marathon takes a lot of time,” Gaudette says. “New runners especially fall into that—injury prevention goes by the wayside when you’re struggling to get in the miles.” But because they aren’t doing the supplementary work, stride deficiencies that stem from lifestyle constraints like sitting and hunching get magnified by the stress of the miles. If they don’t get injured, many decide that a marathon shuffle is simply how they run and they can’t get faster or more efficient.

The marathon also tends to interrupt consistency in training. After racing a shorter distance, from 5K to the half, you can recover by taking a few easy days. Recovery from a marathon takes weeks, even if you’re not damaged from the training or the race. When you begin again, you’ve slid down to a lower rung on the training ladder and have to start the slow climb back up. At best, an up-and-down training schedule never lets you advance because you’re always working back to the same level. At worst, you create a cycle of down-times and too-aggressive recoveries, leading to repeated injuries.

Those who stay competitive for a lifetime maintain a high level of consistent training year ’round, for decades. “The whole key to the longevity thing is getting fit and keeping going,” says McMillan. “Not having forced breaks, but being a little bit more under control so you can stay fit and healthy year after year.”

5. Training for and racing half marathons is more enjoyable.

Running a marathon is satisfying and affirming. You get to prove that you have courage and grit. But it is rarely fun, regardless of your training level.

The half marathon distance, quite uniquely among races, allows you to feel great even when running your best race. In the marathon, regardless of your training, you’re guaranteed to have miles of darkness and despair if you’re pushing for your best time. Running a 5K, you have to push yourself into aerobic distress early and endure it for much of the race. The half-marathon race pace, however, just under your lactate threshold, is defined as “fast, while still fun.” When you’re prepared, it stays fast and fun for most of the race, only getting long in the last couple of miles.

“The race itself is so much more enjoyable. It’s not a sufferfest,” Gaudette says. He sees this as a huge plus in inspiring new runners to continue in the sport. “Get them in the half marathon and it becomes a really fun event. It hooks them into becoming life-long runners.”

Training also falls in a sweet spot for many. “Training for the half is a breath of fresh air,” says McMillan. “It gives you all the fun stuff. You get the long runs—they’re not super long, but they’re long enough that they fatigue you and you get that feel—but you get to do speed too, and stamina. You get to do a nice variety of training, which is a really good way to train.”

READ MORE: Half is the New Full

6. The half’s popularity reserves the marathon as a longer, larger goal.

As far more people run half marathons, the marathon distance—which was downplayed for years by those selling the idea that anyone could do it—is rightfully reclaiming its status as a challenge not to be taken lightly and reserved for better-prepared runners. You can see this in the attitude and language of runners who’ve run the half and are leery and respectful of the full distance. You can also find indicators in the data and experience of race organizers.

In a study of average finishing times over the years, RunRepeat.com found that, while runners on average continue to get slower at all distances, the decline in marathon times has leveled off in recent years, while the average half marathon pace continues to plummet.

“I dug into the numbers and found, extremely surprisingly, that the pace of the half marathon is slower than that of marathon runners, and we see an increasing slow down for half marathon, year by year,” says RunRepeat.com’s founder, Jens Jakob Andersen. The trend suggests that new runners and those aiming simply to complete the distance are now primarily found in the half, while the marathon field is becoming more experienced and finishing with stronger times.

The race organizers at Grandmas Marathon confirmed this with a different observation. They initially added the Gary Bjorklund Half to make the race accessible to those not ready to run the whole 26.2 miles from Two Harbors back to Duluth. From the perspective of the medical staff, “the half got a lot of people in the right distance,” says Shane Bauer, the race’s executive director, as they saw fewer people in distress in the marathon. In the last couple of years, however, Bauer says the biggest concern has switched to the half marathon, given that the majority of new and unprepared runners are tackling it first. And that’s a good thing, as they seem to be learning from having a difficult half without doing much self-damage, and then move up when they’re prepared to handle the rigors of 26.2.

Jonathan Beverly
Jonathan Beverly served as the editor in chief of Running Times from 2000-2015. He is the author of "Your Best Stride: How to Optimize Your Natural Running Form to Run Easier, Farther, and Faster—With Fewer Injuries" (2017, Rodale) and "Run Strong, Stay Hungry: 9 Keys to Staying in the Race" (2017, Velo Press).