Junk Miles: What Are They?

In the running community, there is some debate on junk miles— what they are and if they’re a benefit or a hindrance to your training.

There’s no clear cut answer and while each opinion has its benefits, “junk miles” are a word often thought of as confusing.

While the opinion varies, we’ve detailed exactly what junk miles means and how you can adapt your training plan.

What Are Junk Miles?

Some runners define junk miles as the extra miles tacked onto training that don’t add to developing fitness. These runners don’t care about hitting a target mileage each week. They just want quality workouts— no matter the mileage. This is the negative view of junk miles.

Others say junk miles are definitely those extra miles meant to help hit a mileage target. This includes moderate-paced and recovery runs as well. However, those miles are vital towards building a strong mentality and keeping yourself from injury by incorporating recovery runs.

What’s The Debate?

The debate boils down to a view that “Quality matters over quantity” or a view that “More miles are OK.”

Viewpoint 1: Quality over quantity

Those who see junk miles negatively say that quality running matters over quantity, so these runners typically log lower mileage. Any extra miles that don’t provide specific physiological benefit are wasteful, junk miles.

There’s evidence that suggests reducing mileage and packing your training program with shorter, more intense mileage improves running abilities. The theory is that if you cut back on mileage, you need to increase the intensity to compensate. These runners are training 3-5 days a week and most workouts are done at a high intensity or max speed. Most of the workouts are speed workouts or tempo runs and long runs done at a quicker pace.

But these workouts can also include slow runs as well— as long as they are done correctly. Runs with improper form or unnecessary speed bursts do more harm than good, and in this viewpoint, considered “junk miles.”

More mileage doesn’t always mean faster finish times, studies show. A Swiss study showed that weekly mileage is an “insufficient predictor of individual race times.” The study collected training data, including mileage, from more than 4,000 male runners before a 10-mile race in Switzerland. At the end of the study, race times were scattered.

A 2009 study found that a minute could be shaved off a 10K race when runners cut back their training 25 percent. They did so by adding 12 and 30-second sprints to their program 3-4 times a week for 6-9 weeks.

“Quality over quantity” is one reason why training plans that push for lower mileage with higher intensity have recently become more popular.

Viewpoint 2: More miles are OK

In this opinion, these are the miles that are moderately paced, such as recovery runs, and in this opinion, there are no such thing as junk miles.

Miles like these keep the body from running too fast on easy days and putting the body at risk for injury. Supporters for junk miles say these are necessary because they make sure you recover well and learn to pace yourself as you follow a guided training program.

While it may seem counterintuitive, it’s because of these slower and easier miles that higher mileage sometimes means fewer injuries. Another 2016 study from the Journal of Applied Physiology found that runners logging higher mileage improve their running efficiency more than their lower mileage counterparts.

But there’s another reason why some runners advocate this viewpoint— for the sake of a fun run.

Runners who love the feel of a good run in beautiful weather don’t care if the run was too slow or too fast. It was a completed run. It was fun. It had no purpose but to be a run on a sunny weekend.

Yes, structure and planning is still important to these runners, but they also are OK with a fun run every now and then, a run that stimulates the mind and refreshes their zeal for running. In this viewpoint, you’re never logging junk miles.

Higher intensity or more mileage? Quality over quantity? Mileage that’s just for fun? There are benefits to both sides to the junk miles debate, and it’s a debate that may continue for some time as training plans evolve. What do you think?