Aerobic Vs. Anaerobic Training: What’s the Difference?

When it comes to fitness terminology, it’s easy to throw around words like ‘aerobic’ without actually knowing what they mean. It’s only when we compare it with its opposite, as in aerobic vs anaerobic, that you start to wonder if you truly understand what kind of exercise fits each category.

So, here is an introduction to what makes training aerobic or anaerobic and how that affects your breath, muscles, and metabolism. Plus, how you can maintain your threshold in either form of exercise.

Aerobic exercise

You probably think of colorful 80s legwarmers, eye-catching lycra ensembles, and Jane Fonda workout videos when you hear the word aerobic. 

So, it may be surprising to learn that aerobic means ‘with air’. When it comes to exercise, aerobic refers to how the body produces energy with oxygen.

When it comes to exercise, aerobic refers to how the body produces energy with oxygen.

With all of this access to air, aerobic training is the type of exercise that is quite relaxed and can be maintained for a prolonged period. It is very effective at building your endurance plus strengthening your heart and lungs.

Working out within your aerobic threshold requires you to keep your heart rate within zones 2 and 3 – around 60-80% of your maximum heart rate. The easiest way to do this is with the heart rate monitor on your sports watch, as it will let you know as soon as you start pushing yourself too hard.

Anaerobic exercise

As the name suggests, anaerobic means ‘without air’. You may be wondering how you can exercise without breathing – but that’s not what we recommend your try (because your breath is important).

Instead, anaerobic training is about how your body produces energy with very little oxygen. This occurs when we train at a high intensity for short bursts, pushing ourselves out of our comfort zone, which results in us feeling ‘out of breath’. Anaerobic exercise is an excellent way of improving your fitness levels once you’ve built up your aerobic capacity.

Anaerobic exercise is an excellent way of improving your fitness levels once you’ve built up your aerobic capacity.

Working out within your anaerobic threshold requires you to keep your heart rate within zones 4 and 5 – around 80-90% of your maximum heart rate. Again, the easiest way to do this is with the heart rate monitor on your sports watch, as it will tell you once you’re in these zones and alert you when you begin to dip back to zone 3.

Aerobic vs anaerobic running

By now, you probably get the idea of how aerobic running differs from anaerobic running: it’s all about respiration.

Aerobic running happens on those easy runs. The ones where your pace feels comfortable and perhaps a little on the slow side. When we run aerobically, our breath feels very accessible. 

When we run aerobically, our breath feels very accessible.

Your body receives this oxygen and uses it to produce energy and power your muscles to keep going. It is also able to release the waste products that are water and carbon dioxide with each exhale.

Anaerobic running happens on those hard runs. The ones where you go faster or longer than your body can handle on that particular day. When we run anaerobically, our breath feels challenging to access, creating an ‘oxygen debt’ in our bodies. 

Without the required oxygen level to produce the necessary level of energy, your muscles instead begin to break down sugar (glucose). This means that in addition to water and carbon dioxide, your body also has an additional waste product of lactic acid (used as fuel by the heart).

Unfortunately, lactic acid is much harder for your body to clear away, especially without oxygen. So, the lactate begins to build up, which causes our muscles to feel like they are burning. 

So, which style of running is better? 

Well, it depends on what type of run you are trying to do. Anaerobic running is perfect for putting in a short but intense amount of effort, such as a sprint or when doing interval training.

Anaerobic running is perfect for putting in a short but intense amount of effort

Alternatively, when it comes to marathons, you do not want to start in your anaerobic threshold because this will be unsustainable for the long run ahead. Not only will your body not be able to maintain the intense pace, but it will start producing excess lactate, making your muscles sore.

For long endurance runs like a marathon, you will need to ensure you stay within your aerobic threshold for most, if not all, of the time. Learning how to keep your pace is an essential part of being a runner – and this is where monitoring your heart rate zones can help. Save your sprint for when the finish line is in sight (if you still have it in you).

Aerobic vs anaerobic metabolism

Metabolism is the chemical process that constantly takes place inside your body to help keep your organs functioning efficiently and thus, keep you alive. Essentially, it is how your body receives everything you eat and drink and turns it into energy.

When we exercise, we speed up our metabolism because our body is suddenly demanding more. We breathe faster, sweat more and increase our heart rate as ways of enabling our body to cope with the need to deliver more nutrients to both our muscles and our circulatory and respiratory systems.

As we’ve seen above, our body’s ability to metabolize is affected by whether we are running or working out in an aerobic or anaerobic way. When we maintain our aerobic threshold while running, our body can metabolize fats, proteins, glucose, and glycogen into energy. However, when we speed up into our anaerobic threshold, our bodies can only metabolize glucose and glycogen, and even those are not metabolized as efficiently. 

When we maintain our aerobic threshold while running, our body can metabolize fats, proteins, glucose, and glycogen into energy.

For example, when your body metabolizes glucose, it produces adenosine triphosphate (ATP) molecules used to fuel your muscles. Our body produces 39 ATP molecules during aerobic metabolism, but it only produces three during anaerobic metabolism. 

So, while we may think that pushing ourselves harder and feeling our muscles burn will always ensure we burn more calories, it turns out that aerobic metabolism is just as (if not more) effective. Not only will it power its way through any fat or sugar you may have stored, but it will efficiently turn it into energy, ensuring that you can keep exercising within your aerobic threshold for longer. 

Please note that the information provided in the Polar Blog articles cannot replace individual advice from health professionals. Please consult your physician before starting a new fitness program.