Expert Insights: Is Circuit Training Aerobic or Anaerobic?

Circuit training is both aerobic and anaerobic, which is terrific for many reasons. Our bodies require a balance of aerobic and anaerobic exercises to remain fit, and circuit training adeptly serves both purposes in a single session.

There are tremendous benefits to aerobic and anaerobic exercise, and each should be in your workout routine. Keep reading to learn the differences, the kinds of activities for each, and where circuit training fits into the mix.

What’s the Difference Between Aerobic and Anaerobic Exercise?

Aerobic exercise is a physical activity that…

Utilizes large muscle groups
Includes continuous, repetitive movement

Anaerobic exercise is movement that is…

Intense
Short in duration
Fueled by the ATP system within the muscle

But what does that mean, and why does it matter?

Aerobic and anaerobic exercise differ in three key ways:

The muscle fiber types used
The primary energy sources utilized
The intensity

Every major muscle group in your body is made up of a collection of different types of fibers. The composition of these fibers varies throughout your life, and different kinds of exercise can increase or decrease the proportion of these different muscle fibers.

Aerobic Exercise

Aerobic exercise primarily uses type I muscle fibers, called slow-twitch. These fibers are chock full of blood vessels that help to ferry oxygen in and out of the muscle cells. This readily available supply of oxygen allows for slow and sustained muscle contraction over a long period without fatiguing the muscle.

Activities like running, biking, swimming, and rowing are all aerobic when done at a steady pace for an extended period. The more aerobic exercise you do, the greater the proportion of type 1 muscle fibers in your body, and the more endurance you will build over time.

Anaerobic Exercise

Anaerobic activity relies on type 2 muscle fibers (called fast-twitch) built for power and speed. Instead of a steady stream of oxygen for energy, anaerobic exercises rely on stores of energy already in the muscle to rapidly contract. The downside is that muscle cells have very little energy available at any time, meaning these fibers are quickly exhausted after only seconds of activity.

Thus, less energy in total is produced this way than with aerobic oxidation - the process that powers aerobic activities. Anaerobic activities include sprinting, weight lifting, circuit training, and plyometrics, to name a few.

Health Benefits of Aerobic Exercise

The benefits of aerobic exercise cannot be overstated. Regular aerobic activity can reverse and prevent many diseases, improve your lipid profile, and decrease your blood pressure. Moreover, you can enjoy these health benefits with as little as 150 minutes per week of moderate-intensity movement.

The benefits of aerobic exercise include:

Reverses or prevents cardiovascular disease. Numerous studies have shown that regular participation in aerobic exercise significantly decreases your risk of developing coronary artery disease (CAD) and dying.

Increases your good cholesterol, called high-density lipoprotein (HDL). High HDL levels are associated with a decreased risk of heart disease.

Decreases your total cholesterol. While you want a high HDL, you want a low, low-density lipoprotein (LDL) and triglycerides. Aerobic exercise helps lower these unhealthy cholesterol components, reducing heart attack and stroke risk.

Stunts cardiac remodeling. Cardiac remodeling is a process that occurs after the heart has been damaged and results in structural changes to the heart tissue. These changes often lead to a thickening of the heart muscle, causing it to become stiff and reducing its ability to pump blood effectively. Regular aerobic exercise can slow this process.

Reduces your risk for chronic conditions. Ample research has demonstrated that regular aerobic exercise dramatically reduces your risk of experiencing a stroke, heart attack, or developing diabetes and many types of cancers.

Decreases your blood pressure. Studies have shown that exercise reduces blood pressure for those with hypertension and those with average blood pressure values.

Boosts your mood. Lastly, studies have also shown that aerobic exercise can increase mood for those with and without mood disorders.

Health Benefits of Anaerobic Exercise

Anaerobic exercise has a treasure trove of mental and physical health benefits as well. The CDC recommends some kind of anaerobic activity for two days per week to reap these benefits.

The benefits of anaerobic exercise include:

Builds and maintains muscle mass. Anaerobic exercise is the best way to build and maintain muscle which is essential for multiple reasons. Without it, we lose muscle and bone mass each year, and then our metabolism slows down due to that loss. By maintaining a muscular, strong frame, we prevent age-related disability, keep our metabolism fires burning, and stay coordinated and balanced.

Increases power and strength. More muscle mass combined with proper training means more strength and power. Maintaining strength is especially important as you age, as it is strongly correlated with decreasing fall risk, fracture risk, and hospital stay length in the event you are injured.

Fights muscle and bone loss due to aging. Age-related bone and muscle loss, called osteoporosis and sarcopenia, cause significant issues for aging people, including falls, fractures, disability, and a loss of independence. Anaerobic exercise like weight lifting combats these losses effectively.

Increases your metabolism. Research has shown that anaerobic exercise, such as weight lifting increases your muscle mass, which increases your resting metabolism by 7% on average. This means you burn more calories around the clock – just for being more muscular!

Reduces body fat. Studies have shown that those who partake in anaerobic exercise regularly have a lower body fat percentage than those that don’t.

Boosts your mood. Just like aerobic exercise, anaerobic activity increases mood and energy levels too.

Helps prevent and treat Type 2 Diabetes. Strength training has been shown to increase insulin sensitivity, reduce abdominal fat, and improve glycemic control - critical aspects of health affecting those at risk for or who have diabetes.

Is Circuit Training Aerobic of Anaerobic Exercise?

Now that you understand the differences, how does circuit training fit into this equation?

First, let's define what circuit training is. At its simplest, a circuit is a series of exercises done sequentially with minimal rest in between. Most importantly, circuit training allows us to get both aerobic and anaerobic exercise and all their benefits in a single workout.

What makes circuit training so valuable is that you can completely customize your workout to strike the perfect balance of aerobic and anaerobic activity for you.

Traditional circuit training utilizes strength training exercises performed with minimal rest. You could set up a circuit using machines, free weights, or even bodyweight exercises. This fulfills our anaerobic component.

Aerobic exercise comes from minimal rest in between stations. Your heart and lungs are challenged more the less rest you take.

Think of it like a seesaw, with one side being aerobic and the other being anaerobic. If you use heavier weight and higher intensity movements, you are tipping toward the anaerobic exercise side. If you use lighter weights or continuously perform movements for longer periods, you tip toward the aerobic side.

You are getting both kinds of activity in the same workout, but which type you get more of will depend on how you structure your session.

Combined, circuit training is a fully customizable, aerobic, and anaerobic workout that delivers all the benefits in a shorter, more efficient workout.

Aerobic Circuit Training Exercises

There are a few essential considerations when designing any workout program.

What is your primary fitness goal? You should narrow it down to one so that the workout is tailored to your goal specifically.
What kind of movement do you enjoy? What do you dislike? Except for professional athletics, there is no reason you have to do something you truly hate to be healthy. On the contrary, the more you enjoy movement, the more likely you are to stick to it in the long term. So if you haven't found anything you like yet — keep trying!
Specifically for circuit training, what side of the seesaw do you want to lean toward? Aerobic or anaerobic exercise?

Remember that aerobic exercise is performed continuously, at a steady pace. Here is a list of aerobic exercises you can include in your circuit training:

Running
Jogging
Walking
Cycling
Rowing
Swimming
Dancing
Hiking
Kickboxing
Jumping rope
Mountain climbers
Jumping jacks
Running in place

Anaerobic Circuit Training Exercises

On the other side of the equation, we know that anaerobic activity is about movements with higher intensity performed quickly.

There are endless exercises and combinations that will increase your anaerobic fitness:

Free weights
Powerlifting
Olympic weight lifting
CrossFit
HIIT
Insanity
Body weight exercises like push-ups, pull-ups, sit-ups, etc.
Kettlebell exercises like swings, squats, halos, etc.
TRX
Burpees
Sprinting
Squats
Deadlifts

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Types of Circuit Training

Circuit training is classified by how you can organize your work and rest periods. While you can use circuit training concepts for things like endurance sports, typically, circuits consist of strength exercises, body weight exercises, and aerobic movements.

Three common types are circuit training:

Repetition Circuit

This can be an excellent option for increasing muscular endurance, cardiovascular health, and fat loss. First, decide how many repetitions you want at each exercise station and how long to rest between exercises and after completing your circuit before starting again. Repetition circuits are a multi-purpose and easily modifiable workout style well-suited to most fitness goals.

Timed Circuit

Another great option that develops our cardiovascular health and muscular endurance. Repeat one exercise at a time for a set time frame (for example, 60 seconds at each exercise station) before moving on to the next exercise station. Timed circuits are best suited for improving general fitness and heart health or as a cardio supplement for a fat-loss program.

As Many Reps/Rounds As Possible (AMRAP) Circuit:

Similar to a timed circuit, this set-up puts you in competition with yourself from set to set or round to round. First, you complete the exercise in the allotted time and achieve as many repetitions as possible at each station. Then your next round, you try to get more reps than last time. This is a fun way to push yourself and measure your progress from week to week. Of course, you can also do as many rounds as possible, attempting to achieve as many rounds of the circuit in a prescribed time. AMRAPs are great if you have a competitive streak and like to track your fitness progress.

Conclusion

Our bodies require aerobic and anaerobic activity to stay strong and healthy. Aerobic activity is essential for cardiovascular health, preventing disease, and maintaining endurance. Anaerobic exercise keeps our muscles and bones strong, supports our metabolism, and helps prevent chronic health conditions like diabetes, stroke, and heart disease.

A well-balanced exercise program should include both aerobic and anaerobic exercise, and there are endless options for achieving that in a fun and engaging way.