Feel the Burn

In the last blog ‘Update Your CV’ we explored ways of improving our cardiovascular fitness through aerobic exercise. In reality though this is only half the story. Although we often hear a lot about aerobic exercise and how it improves fitness, reduces our risk of lifestyle diseases, and helps with weight management, we hear much less about another type of cardiovascular exercise, aerobic exercise’s more intense cousin, ‘anaerobic exercise’.

So what is anaerobic exercise?

While aerobic means ‘with oxygen’ anaerobic means ‘without oxygen’. Anaerobic exercise is short lasting, high intensity activity where your body’s demand for oxygen exceeds it’s supply. In other words you cannot breathe quickly enough or deeply enough to get adequate oxygen for said activity. So anaerobic exercise relies on energy sources that are stored in our muscles and unlike aerobic exercise is not dependent on oxygen.

How do you exercise anaerobically?
This sort of activity uses our muscles at a high intensity for a short period of time, therefore you can pretty much adapt any aerobic exercise into anaerobic exercise by increasing the intensity at which you work. If we take running as an example, the 100m sprint is anaerobic and a half marathon is aerobic, different intensity and therefore different duration.

Just to muddy the waters a little we rarely work purely aerobically or anaerobically, there is nearly always a collaboration between the two energy systems and in fact the anaerobic energy systems can be broken down even further with one lasting for around 10 seconds and the other lasting for up to 4 minutes, but lets not go there just now.

Typical examples of anaerobic exercise include heavy weight lifting, all types of sprinting whether running, cycling, swimming, rowing, jumping etc, hill climbing, interval training (especially High Intensity Interval Training HIIT) or any rapid burst of hard exercise.

How does anaerobic exercise benefit you?
Because of the shorter more intense bursts it can:

  • Develop stronger muscles

  • Improve your VO2 max (the highest amount of oxygen that you can consume during exercise) and thus also improve your cardio respiratory fitness

  • Increase your capacity to withstand the build up of waste substances (such as lactic acid) and remove them from the body. This means that your endurance and ability to fight fatigue will improve.


Overall, although pure anaerobic exercise burns fewer calories and is somewhat less beneficial for cardiovascular fitness than aerobic exercise because of its short duration, if you incorporate anaerobic exercise into an interval session that lasts the same amount of time as an aerobic session you will burn far more calories and really tax your cardiovascular system. Anaerobic exercise is very good at building strength, speed and muscle mass.

My recommendation if you are a beginner is to start gently (as with everything) using aerobic activity and then slowly introduce more intense activity as you become fitter, stronger and more able to cope with the increased demands anaerobic activity places on your body.

Next month we will delve a little deeper into strength and hypertrophy (muscle building).

Whatever you are doing, enjoy it; you should feel the burn, not the pain.