You’ve probably heard the term “aerobic exercise” countless times, from gym class to long runs to government guidelines. But anaerobic? Probably not as much. Even if you’re familiar with both terms, can you define what aerobic versus anaerobic exercise really means?
Whether you’re an experienced runner who’s been pounding the pavement and racking up race medals for years or you’re new to the sport of checking off miles by foot, paying attention to aerobic and anaerobic exercise—and making sure you’re getting both—is crucial for staying in shape and performing at your best.
Read on to learn about each type of exercise, plus get expert tips on how much of aerobic versus anaerobic exercise you should be getting and how to incorporate both into your routine.
The Difference Between Aerobic and Anaerobic Exercise
Though they seem like simple concepts, what’s happening in your body during these two types of workouts can get kind of complicated and pretty scientific. But on a very basic level, aerobic exercise means you’re exercising at an intensity in which you’re able to take in more oxygen than you need—an effort you can sustain for a decent amount of time.
“The word aerobic, quite literally, refers to exercise with oxygen,” explains Juli Benson, Olympian and head coach of Tracksmith-sponsored Colorado Springs Track Club Elite. Think: longer outings at a pace where you can hold a convo with your running buddy.
During aerobic workouts, your body uses oxygen to create adenosine triphosphate, more commonly known as ATP, a molecule your cells use for energy so you can push through that workout.
When you do anaerobic exercise, on the other hand, there’s not sufficient oxygen present in the body for your cells to create ATP for energy. Instead, they have to break down sugar to power your movement (and create excess lactate in the process), says Jeff Gaudette, the San Diego–based owner and head coach of RunnersConnect.
The anaerobic process kicks in during sprints or during heavy weightlifting. You can’t keep up anaerobic-level intensity for long because the build up of lactic acid leads to a reduction in your speed and power.
Benefits of Aerobic Exercise
It may seem obvious that aerobic workouts are crucial for runners—they make up the vast majority of runs most of us do. All those long, easy, conversationally paced runs fall into this category. “The aerobic system is what powers 90 percent or more of our running, even during races,” says Gaudette.
But that’s not all. All those aerobic runs help you kick it into high gear, too. “Aerobic fitness is also crucial to being able to compete and sprint at the end of a race,” says Benson. “The more aerobically fit an athlete is, the longer into the race an athlete will save using muscle glycogen as fuel.”
Benefits of Anaerobic Exercise
Any workouts that involve sudden bursts of speed—such as 400-meter repeats or hill sprints—with short rest periods in between are anaerobic. If you stick to easy-paced jogs and have no plans for toeing a race start line, you might assume you don’t need to do any anaerobic workouts, but you’ll still gain big benefits from adding them to your schedule.
“Many times runners want to get the most bang for their buck when training and will often rely solely on training the main energy system required for the race—their aerobic fitness,” says Benson. “But a major downside of that would be a missed opportunity to work on strength and improving running economy.”
That’s because anaerobic workouts improve the body’s ability to deal with lactic acid build up, Benson explains, so it takes a longer period of time in a race before that lactic acid will form and when it does, your body processes it better so you don’t fatigue as fast. Also, with improved running economy and efficiency, you also gain enhanced power and ground contact time, resulting in less effort when you run faster. Easier, faster runs from anaerobic exercise? Sign us up.
The Balance Between Aerobic vs. Anaerobic Exercise
Regardless of your goal distance—whether you’re gearing up for an ultra or just want to crank out a couple miles at a time—you need both aerobic and anaerobic workouts in your week. “Aerobic workouts form the base of your endurance so you can run longer, and anaerobic workouts help you improve the efficiency at which you can run,” says Gaudette. “Improving both allows you to make constant progression.”
One general rule, though: Don’t add too many anaerobic sessions to your routine too quickly. “Many runners begin to include anaerobic workouts too soon in their training when they would benefit more from focusing on their aerobic system,” says Gaudette. “The anaerobic system can develop quickly, whereas the aerobic system takes years to fully develop.”
He advises keeping aerobic running as the majority of your mileage base; it should make up at least 80 percent of your training. Work anaerobic sessions in for only about 5 to 10 percent of your total training. That means you really only need a speed workout in your routine once every week or two to achieve well-rounded fitness and reach your next personal best.
Also, a note for those new to running: You’ll want to stick mostly to aerobic workouts while you’re starting out, Gaudette says, so you can build that base. Then, after about two to three weeks of about 20 miles per week or when you’re able to handle 30 to 60 minutes of easy running four to five days a week, that’s when you can add in that one anaerobic session per week.
Finding a balance between these two types of training is all about making sure your body can handle the challenges you throw at it—whether aerobic for endurance or anaerobic for efficiency.