The Ultimate Guide to One of Our Best Training Tools: Long Runs

Going the extra km(s) can help you run more efficiently at every distance—even if you dread it sometimes.

Ah, long runs: We love to hate ’em. Or maybe we love to love ’em—depends on who you ask. Either way, the long run is the cornerstone of any half marathon or marathon training plan, but it can be equally important to your 5K and 10K training. No races on your calendar? No problem. A long run can still be beneficial for your overall fitness and mental health.

But if you don’t understand the long run, you may miss out on all of the magic it has to offer. So we put together this ultimate guide to one of the best training tools you have in your arsenal.

What’s the point of the long run?

The benefit of running long—regardless of the distance you’re training for—is the aerobic gain you’ll make during those kms. “Long runs force the body to become more and more efficient,” says Ben Rosario, head coach and founder of the Hoka NAZ Elite team in Flagstaff, Arizona. “The heart learns to pump higher amounts of blood with each stroke, which then carries more oxygen to the body.”

Aerobic (or endurance) running also strengthens your slow-twitch muscle fibers, which can fire repeatedly with minimal fatigue (compared to fast-twitch fibers, which are used during short, explosive efforts but fatigue more quickly). These fibers are also important because they’re full of capillaries, mitochondria, and myoglobin (an iron- and oxygen-binding protein), all of which are crucial to getting a steady supply of oxygen and energy to the muscles.

“Long runs force the body to create new capillaries, giving the oxygen a smoother and faster path to the mitochondria—a.k.a. the ‘power plant’ of the cells—where energy is produced and stored. Andwhen we run for long periods of time, the size of those mitochondria increases, allowing them to produce and store more energy,” explains Rosario.

One of the other major benefits of the long run is how it teaches your body to use fat as fuel over carbs, says Joe McConkey, a Boston-based exercise physiologist and USATF-certified running coach. “That allows you to be more efficient with your different forms of energy, so you can run faster without depleting your reserves.”

Translation: The long run prepares your body to run more efficiently no matter the distance—even in a short race, when you need energy to be produced and oxygen sent throughout the body fast.

And you can’t overlook the mental angle: To prepare for the psychological challenge of racing for hours, you have to train for hours. Even if you’re not racing, a long run offers your mind the chance to tap into the ever-elusive runner’s high, and research shows running can boost your mood and improve your mental health.

What to Watch Out for On a Long Run

A long run is, inherently, long. And the more time you spend on your feet, the more stress you put on your body. “The long run does ask a lot of our muscles, tendons, and ligaments due to the duration of exercise required for a run to be considered ‘long’,” says Rosario.

Generally, your cardiovascular system adapts to changes more quickly than your musculoskeletal system. So if you start running long before your body is prepared to run long, you could put yourself at an increased risk for injury, including overuse injuries like plantar fasciitis, Achilles tendonitis, runners’ knee, iliotibial band (ITB) syndrome, and shin splints.

“If you’re experiencing any little niggles or asymmetries before the long run, the long run will only make those worse with the thousands and thousands of steps you’re putting on your body,” says McConkey. It’s super important to listen to your body and, if you feel like something is off during the long run, acknowledge that it may be more major than you think. “The only sensations you should feel during a long run are a slight challenge aerobically as it gets longer, and general fatigue or a sort of bilateral soreness,” he adds.

Gear You Need for a Long Run

Running is a pretty simple sport in terms of gear, but when you start clocking over 60 minutes, there are some important things you’ll want with you beyond a good pair of shoes.

The most important addition is a way to carry fuel and hydration, whether that’s a running belt, a handheld water carrier, or a pack.

“If your long run is longer than 90 minutes in duration, you’ll want to make sure you’re carrying electrolytes in the form of a drink or gel,” says Rosario.

Here’s why that 90-minute cutoff is so important: “If you don’t fuel properly, after 90 minutes—and especially after two hours or more—you’ll start depleting your glycogen stores,” explains Rosario. “Glycogen equals energy. If you’re not replacing what you’re losing through prolonged exercise, you could run out of energy.” That’s what runners call bonking or hitting the wall.

In general, runners should take in 30 to 60 grams of carbohydrates per hour during a long run. McConkey recommends consuming some kind of fuel every 15 minutes or so, alternating between a liquid and solid form.

Speaking of liquids, even minor dehydration leads to a reduction in endurance performance, as well as a higher rate of perceived exertion. If you’re training for longer than an hour, you should be drinking anywhere from 700ml to 1L per hour of your run (sipping sporadically, not chugging in one go). You can actually calculate how much fluid you need per hour by weighing yourself before and after an hour of running sans water; each pound of weight loss is approximately equal to 470ml of fluid deficit. (Or simply use our handy hydration calculator here.)

If you’re running long, you also may want to wear headphones to play music or a podcast to keep you from getting bored and carry a phone and credit card or cash in case of an emergency.

How Long Should Your Long Run Be?

There’s a huge amount of variation in how long a long run should be, depending on the type of runner you are.

Some coaches suggest long runs cover one-and-a-half to two times the distance of what you consider a normal-length run. Most experts, like Jack Daniels, agree that a long run be about 20 to 25 percent of your overall weekly kms. So if you’re running 65km per week, your long run will be 12 to 16kms

“I typically don’t like the long run to be more than twice the length of a regular recovery run,” says McConkey (in general, recovery runs last about 25 to 40 minutes). According to the Road Runners Club of America, a long run technically isn’t a “long run” unless it’s over 90 minutes, so the exact distance depends on your running pace.

But your long-run distance becomes more specific if you’re training for a certain distance. Remember: You need to go further (and slower) in order to run faster at shorter distances. Most experts recommend working up to the below peak long run for each distance:

  • 5K: 8 to 9 kms for beginners; 16 to 19 km for intermediate/advanced
  • 8K/10K: 10 to 16 km for beginners; 19 to 22 km for intermediate/advanced
  • Half marathon: 19 to 20 km for beginners; 25 to 28 km for intermediate/advanced
  • Marathon: 29 to 25 km for beginners; 28 to 32 km for intermediate/advanced

Yes, some of those distances are longer than the race itself. “But logging those kms shows you’ve spent enough time at sub-max speeds to allow the necessary aerobic adaptations to happen,” he explains.

How Fast Should Your Long Run Be?

No matter the distance, your long run should be run at an easy pace, says McConkey. We will repeat: easy pace! What does that translate to? It’ll be different for every runner, but an easy pace should fall on the lower end of the rate of perceived exertion scale. Your heart rate should be 50 to 70 percent of your maximum heart rate, and you should be breathing naturally and able to hold a conversation effortlessly.

“I advise people to run as slow as possible, as long as it’s mechanically comfortable,” McConkey explains. “I challenge people to not look at pace until they’re done, but just focus on something comfortable. You shouldn’t feel like you’re doing slow-motion single-leg squats; there should still be some spring to your step.”

That pace is going to change as your fitness changes. “When you develop more strength and running efficiency, you’ll be able to run faster at the same RPE or heart rate,” says McConkey.

For shorter distances, long runs can generally be slow and enjoyable, says Rosario. But half marathoners and marathoners should approach their long runs with a little more structure. “Half marathoners and marathoners, in my opinion, should be adding faster-paced running into most of their long runs: things like alternating fast-pace and medium-pace kms, surging for two minutes at the beginning of each kms, or simply running the last 5K of their long run really fast,” says Rosario. This is important, because it helps train your legs to get used to running fast even with lots of kms on them—and that will help at the end of races.

How to Recover From a Long Run

You may run your long run at an easier pace, but the sheer amount of time you’re spending on your feet warrants more rest and recovery.

For starters, “the quicker an athlete can replenish after a long run, the sooner they will recover,” says Rosario. “Shoot for a mix of carbs and protein, preferably at a 4:1 carbs to protein ratio—that particular ratio has been shown in labs to be the most effective at replenishing muscle glycogen stores and thus limiting muscle damage.”

McConkey recommends taking the day off after a long run. “Instead of running, just walk around for 20 to 30 minutes and spend 10 minutes on a foam roller to open up your body,” he says. “Those two things can really expedite recovery.” In fact, foam rolling was shown to reduce delayed-onset muscle soreness while enhancing muscle recovery in a study published in the Journal of Athletic Training.

As for other trendy recovery modalities, do what feels good to you. Compression boots can also lead to recovery benefits, a study in the Journal of Applied Physiology found. Ice baths were shown to reduce delayed onset muscle soreness in a scientific review by researchers at the Cochrane Library. And massage helped reduce pain intensity in runners’ quads in a study from the Journal of Physiotherapy.

Most importantly, prioritize a good night’s sleep—new research from the International Journal of Sports Medicine argues it may be the single most important factor in exercise recovery. After all, that’s where the real recovery magic happens, when your body truly has time to rest and rebuild.

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