The difference between brisk jogging and more intense workouts such as interval training or weightlifting lies in the type of energy system your body uses to fuel these exercises: aerobic vs. anaerobic.
Whether you prioritize aerobic or anaerobic exercise depends on your goals, but a balanced fitness routine should include both. Learn the difference between the two types of exercise and what happens in your body during each exercise.
Anaerobic exercise and aerobic exercise: what is the difference?
The textbook distinction between aerobic and anaerobic exercise is whether oxygen is used to generate the energy needed for the effort. “During aerobic exercise, the body relies primarily on oxygen to generate energy; this is not the case during anaerobic exercise,” says Trevor Thiem, CSCS.
In reality, whether an exercise is aerobic or anaerobic is determined by its duration and intensity.
anaerobic exercise
According to kinesiologist Frances Lee Smith, MS, PN1, anaerobic exercise “can only be performed in short repetitions and requires a significant amount of recovery[between exercises].”
To work at this level, you need to be diligent with each burst of physical activity and work at a pace that you can maintain for up to two minutes. Examples of anaerobic exercise include:
Most of BODi’s programs can be classified as primarily anaerobic.
aerobic exercise
Aerobic exercise, on the other hand, is typically done “at a slow or moderate pace for long periods of time,” Smith says. In practice, this usually involves any activity that lasts more than 2-3 minutes and typically includes what trainers refer to as low-intensity exercise and steady-state cardio.
Examples of aerobic exercise include:
How the body uses both energy systems during exercise
Technically, the body does not rely solely on aerobic or anaerobic energy production.
“Three different systems are used to produce energy: two anaerobic and one aerobic. All of these are on at all times, whether you’re walking the dog, swimming laps, practicing intervals on the track, or pumping iron,” Thiem says, adding that all three shift into a higher gear when you start exercising. “However, the intensity and duration of each match will determine which system is emphasized.”
When you begin exercising, your body cannot immediately meet your energy needs with the current available oxygen supply, so it uses anaerobic respiration (also called anaerobic metabolism) to make up for what is known as “oxygen deficiency.”
Anaerobic respiration remains one of the main sources of energy when performing short, repeated exercises (sprint intervals, squats, curls, etc.). The reason is that its production rate is so fast, in fact much faster than aerobic respiration, that it can meet the immediate high energy demand from the muscles.
However, once exercise time exceeds 2-3 minutes, aerobic metabolism (which has higher production capacity but slower production rate) has time to speed up and aerobic metabolism takes precedence.
Here we provide an overview of how the three energy systems (phosphagen, glycolysis, and oxidation) interact during exercise.
Use of energy systems by intensity and duration of exercise
| strength | interval | Energy system used |
| very high | 0-6 seconds | Phosphagen (anaerobic) |
| very high | 6-30 seconds | Phosphagen and glycolysis (anaerobic) |
| expensive | 30 seconds to 2 minutes | Glycolysis (anaerobic) |
| Moderately | 2-3 minutes | Glycolytic and oxidative (aerobic) |
| low | 3 minutes+ | oxidative (aerobic) |
Anaerobic vs. aerobic exercise: Which is better for your goals?
“I recommend mixing everything together,” says Smith. “It’s important to challenge your mind and body in different ways,” she says. This means that a balanced exercise program for general fitness should include both anaerobic and aerobic exercise. This is because anaerobic and aerobic exercise build different skills and tend to produce different results.
- Anaerobic exercise typically improves muscle mass, strength, and power, as well as overall speed.
- Aerobic exercise typically increases endurance and has a great impact on cardiovascular health.
Even if you’re focusing on a goal that’s aerobic in nature, like running a half marathon, doing anaerobic exercise will improve your performance.
For example, strength training can help runners improve their speed, economy, power output, time to fatigue, and even VO2 max, not to mention reduce their risk of injury. On the other hand, if your main goal is strength training, doing some light cardio in between your workouts can help optimize your recovery.
Are you focused on weight loss? do anaerobic exercise
But if your goal is weight loss, the type of exercise science recommends may surprise you: anaerobic exercise. “Research shows that anaerobic exercise typically results in greater fat loss than aerobic exercise, primarily because anaerobic exercise maintains an elevated metabolic state for a longer period of time after exercise,” Thiem says.
This idea goes against the common wisdom (not based on science) that slow and steady exercise wins the fat loss race. But if you think back to the idea of creating oxygen deprivation, it makes sense. When performing anaerobic exercise, the body does not switch to aerobic metabolism to compensate for the initial lack of oxygen, as is the case with long-distance running, for example.
In fact, oxygen deprivation gets worse and eventually becomes oxygen debt. The process of paying off that debt keeps your body’s metabolism in an elevated state for hours (and even days, according to some studies) after you stop exercising. White Coat calls this phenomenon excess post-exercise oxygen consumption, or EPOC. You may know it as the “afterburn effect.”
In any case, the conclusion is: Aerobic exercise may burn more calories during the workout simply because the workouts tend to last longer, but anaerobic exercise typically burns more calories overall because it maintains an elevated metabolic rate for a longer period of time after it’s finished.
How to determine if a workout is aerobic or anaerobic
heart rate monitor
A heart rate monitor is the most accurate way to determine whether you are exercising in the anaerobic or aerobic zone. “When you exceed 80% of your maximum heart rate, you become anaerobic,” Thiem says.
talk test
If you don’t own or don’t have access to a heart rate monitor, try the Talk Test. “If you find it difficult to speak even short sentences, or if you rate your exertion at a 15 or above on a 20-point scale, you’re doing anaerobic exercise,” Thiem says. If you can hold a conversation, you’re getting aerobic exercise.
In practice, that might mean slowing down if you find it difficult to talk during a 9-mile run, or running a little harder if you can talk politics with a friend during a FOCUS T25 workout. But, as always, remember that your fitness level is a key factor. “If you’re just getting started with fitness, I don’t recommend jumping straight into 40-yard sprints,” says Smith, “but a 20-minute jog might be doable.”
Your goal is to walk the line between pushing yourself enough to optimize your progress and pushing yourself so much that you end up getting sidelined by overtraining. “Talk testing helps you stay on track,” Thiem says.
