What Is Anaerobic Exercise and How Can It Boost Running Performance?

Hill repeats. Intervals sprints. Heavy lifting. Whether you realize it or not, anaerobic exercise may already play a part in your workouts. And if it doesn’t? Well, it might be time to add this type of training to your schedule.

“There are numerous benefits of doing anaerobic workouts,” certified strength and conditioning specialist Janet Hamilton, C.S.C.S., an exercise physiologist and running coach with Running Strong in Atlanta tells Runner’s World. And these advantages apply to all runners.

Below, we get clear on what anaerobic exercise is, its benefits for running performance, the best anaerobic exercises, and how to incorporate the high-intensity form of exercise into your workouts.

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What is anaerobic exercise?

Let’s start with a quick physiology lesson. To perform any type of movement, your body needs energy. And there are three main systems your body uses to make that energy: the phosphagen system, the anaerobic glycolysis system, and the aerobic system, according to the American Council on Exercise (ACE).

Per ACE, the phosphagen system is used for really brief bursts (think: five to 10 seconds) of max-effort exercise, such as the beginning portion of a sprint or a single power-lifting move. The anaerobic system comes into play for slightly longer bouts (up to three minutes) of intense movement, like sprinting a lap around the track or busting out a set of heavy barbell squats. And the aerobic system dominates when there’s low- to moderate-intensity exercise that you can sustain for longer periods of time, such as running at a comfortable pace for a couple miles or casually biking around your neighborhood.

“Anaerobic” means without oxygen, so when you do anaerobic exercise, your body does not rely on oxygen to fuel the activity. Instead, it taps into a form of energy called glycogen that is already stored in your cells, says David A. Wang, M.D., primary sports medicine physician at the Hospital for Special Surgery in Paramus, New Jersey.

Your body only has so much glycogen stored in its cells, so when that runs out—which happens after about 30 seconds to up to 3 minutes—then your body starts using oxygen to fuel itself, says Wang. When oxygen comes into play, the exercise lessens in intensity and becomes aerobic.

Quick nuance: Your body is using all three of its energy systems all the time, says Hamilton. “It’s just, depending on the activity, one system will dominate versus the others,” she explains. And in general, when you’re doing short bursts of high-intensity exercise, your anaerobic system is taking the reins, relying on glycogen for fuel, and qualifying those movements as anaerobic exercise.

What are the benefits of anaerobic exercise for runners?

You may think anaerobic exercise only matters for athletes who primarily train and perform in the anaerobic zone, like sprinters, hurdlers, and powerlifters. But that’s actually not true. Any runner can benefit from anaerobic training, says Wang.

One big boon of anaerobic training is that it recruits and thus strengthens fast-twitch muscle fibers that you normally don’t recruit during your longer, easier-paced aerobic workouts, says Hamilton. “Your fast-twitch fibers contribute to the power that you need to do things like run uphill, or surge at the finish line, or push your pace in a sprint,” says Hamilton. These fibers can also help you power through a long-distance race when your slow-twitch fibers start fatiguing.

No matter what type of movement you’re doing, your slow-twitch fibers are pretty much recruited first, explains Hamilton. But if they aren’t strong enough to meet the demand you’re putting on them, then your fast-twitch fibers get called on next. Say you’re doing a long duration activity (think: anything from a 5K to a marathon) at race effort, at some point your slow-twitch fibers will fatigue. Your body will then naturally try to recruit your fast-twitch fibers, but if you haven’t previously trained those muscle fibers, they won’t do you a lot of good.

With anaerobic training, you can effectively strengthen your fast-twitch fibers so that “when you need them on race day, they’re strong and ready to go,” says Hamilton. This means you can run stronger for longer without hitting a wall or losing your speed.

These benefits can carry over into your workouts, too. For example, strengthening your fast-twitch fibers through anaerobic exercise can help you climb hills and tackle long runs without feeling quite as gassed. “A lot of that is because you have recruited and strengthened muscle fibers that you had not been recruiting and strengthening before,” says Hamilton.

Additionally, doing sprint workouts, which are a form of anaerobic exercise, can increase your foot speed, decrease your ground contact time, and improve your form—all of which can make you a more efficient runner, says Wang.

Lastly, strengthening your muscles through heavy weightlifting (another form of anaerobic exercise) can help support and protect your joints, which can reduce your risk of injuries while running, says Wang.

What are the general health benefits of anaerobic exercise?

Both anaerobic and aerobic exercise are positively associated with improved cardiovascular health, according to a 2017 review published in the World Journal of Cardiology.

But anaerobic exercise—specifically, weightlifting—is unique in that it can build and maintain muscle mass more so than aerobic exercise, says Wang. Anaerobic exercise can also help strengthen your bones, he says.

Another general benefit to anaerobic exercise: It’s performed at shorter durations than aerobic exercise, making it more convenient to slot into a busy schedule, says Wang. With an anaerobic-focused workout, you don’t have to spend an hour or even 30 minutes continuously pounding the pavement. Instead, you can do high-intensity intervals or targeted strength training for 10 or 15 minutes and gain advantages for your fitness and performance.

What are the best anaerobic exercises for runners?

Weightlifting is a great form of anaerobic exercise for runners, says Hamilton. In particular, Olympic-style lifting exercises that require explosive strength (think squats, snatches, and clean and jerks) can really strengthen your hips, core, and legs, all of which are power muscles in running, says Hamilton.

Most forms of weightlifting count as anaerobic exercise because they are short in duration (sets of 8 to 12 reps are common and that amount of work takes less than 2 minutes, says Hamilton), and demand a high level of energy. But bodyweight plyometric moves—like box jumps and squat jumps–can also count as anaerobic because those are challenging moves you’d likely only be able perform for a short duration of time. Basically, any exercise that you do for less than 3 minutes and that takes a big effort to execute can check the box as anaerobic work.

Max-intensity sprints are another good anaerobic exercise, adds Hamilton. The strength and motor patterns trained during sprints carry over well into other types of running. These sprints would be short—think two minutes or less—and performed at an all-out effort, she says. For example, you could sprint for 1 minute and recover for 4 minutes, and, depending on your fitness level, repeat that 2 to 3 times. Over time, you could gradually build up to 4 to 5 sets of those sprints, says Hamilton.

Alternatively, if you’re brand new to anaerobic training, you could start out with very brief sprints—think 10 seconds—followed by long recovery, like 2 minutes. Then, depending on your fitness level, you could repeat that 4 to 5 times before gradually working your way up to 10 sets, says Hamilton.

The amount of rest you need in between sprints in an anaerobic workout depends on how quickly you recover. The goal is to have enough down time in between sprints so that you fully recover—meaning, your heart rate returns close to baseline level and you’re able to perform at max effort again for the next repeat. In general, the longer your sprint distance, the more rest time you’ll need before attempting that effort again.

How do you incorporate anaerobic exercise into your routine?

If you’re brand new to anaerobic training, ease into it slowly so that your body has time to safely adapt. “With anaerobic training, you definitely want to take days off in between to allow your body time to rest and recover,” says Wang. Ramping up too quickly can increase your risk of injury, he warns.

The right pace at which to introduce anaerobic training varies person to person, so it can be helpful to tap a qualified coach or trainer for personalized advice. That person can also give you good form and technique tips for sprinting at max effort and/or lifting heavy, and they can watch your form while doing so.

Whether or not you enlist an expert, it’s important to pay attention to how your body feels during and after an anaerobic workout. “If you’re sore for days after a new workout, then that probably was a little bit too much for you,” says Wang. “You want to make sure to listen to your body and never push through your kind of soreness or pain.”

With anaerobic resistance training in particular, be extra mindful about proper form and use lighter weights until you’ve got the technique on lock, says Hamilton. Make sure you thoroughly warm up your joints and muscles before trying to lift heavy and that you don’t push yourself to a place where you over fatigue your muscles. “Work to a point where you sense your form will falter if you keep going but stop before it does,” says Hamilton. Avoid doing a heavy weight workout on the same day that you’re doing another intense form of exercise, like speed intervals or a long run, she says.

Lastly, keep in mind that although there are legit benefits to anaerobic exercise, it’s not the only type of training to focus on. “You should be doing both anaerobic and aerobic training as part of your routine,” says Wang. This can help you be as strong and well-rounded a runner as possible. Having the mix will get you ready to take on long miles, while also preparing you to maintain a strong pace through each step.