The take-home message? Your anaerobic system fuels your body during exercise that’s so intense you can’t keep it up for more than a couple minutes at a time.
That said, your metabolism doesn’t work on a toggle. You don’t switch from 100% using one energy system to 100% using another one. In your body, aerobic and anaerobic metabolism are both humming along at all times. Your body just emphasizes one over the other depending on how much energy you need to keep with whatever it is you’re doing, Lawton explains.
What are the benefits of anaerobic exercise?
The many benefits of using anaerobic metabolism to power your workouts come down to one word: intensity.
Working at a high intensity during exercise is a big part of improving your cardiorespiratory fitness, allowing you to become faster, more powerful, and stronger. It’s the principle behind true HIIT, in which you intersperse short periods of hard, near-max work with longer, easier periods of recovery, Lawton says.
Research shows that high-intensity, anaerobic-metabolism-dependent exercise is effective for building muscle, getting faster, or becoming more powerful and explosive. This can help you crush PRs in the gym and beat your opponent to the soccer ball, Pennington says. Plus, it’s time efficient. With interval training, you can gain many of the benefits of long, slow workouts in less time.
Another, not-so-known benefit? Working each system helps the other get better too. By performing anaerobic exercise, you actually train your aerobic metabolism. When you build strength, you are also boosting your endurance—meaning, more time before you get wiped out by your cardio. And the fitter your aerobic system gets, the harder you can work without your anaerobic metabolism giving out. So if you add things like sprint intervals to your routine, you may find your long and slow runs don’t feel quite so difficult, Pennington explains.
“Regular anaerobic exercise also improves your energy levels,” he says. “It increases your body’s ability to store glycogen, giving you more energy during intense physical activity.” You can work out and play harder, longer—and that only adds to the benefits of any exercise.
How to use anaerobic exercise in your workout routine
All these anaerobic exercise benefits don’t mean, though, that your workout routine should consist primarily, or even mostly, of it. There’s a fine line between pushing and pushing too hard. To get the greatest benefits of high-intensity anaerobic workouts, you need to rest both during and between your workouts.
If the human body can only maintain anaerobic exercise for two or so minutes at a time (and max max efforts even less than that), high-intensity intervals can’t be any longer than that at a time and still focus on your anaerobic system, Pennington says. And your body can’t fuel another true anaerobic interval unless you’ve rested for at least triple (but sometimes even more) the amount of time you worked. So if you want to put that practice to work—after a solid warm-up, of course!—work as hard as you possibly can for 10 seconds, then rest for 30. Repeat.
Similarly, between your high-intensity anaerobic workouts, your body needs rest to refuel and recover. The more intense your exercise sessions, the more rest you’ll need. In general, perform high-intensity on nonconsecutive days—meaning, at least 48 hours between HIIT routines. Between your workouts, turn to straight recovery and light aerobic activities like walking, jogging, or low-intensity strength sessions, Pennington suggests. That way, your body will be ready to go all in for your next max-out workout.