You probably have at least one “super fit” friend. Maybe they’re a marathon runner, a footy player or a keen hiker.

To keep themselves healthy, they may stick to a strict exercise regimen and only eat certain foods.

But in most cases, these people would likely struggle to play a sport or do an activity they’re unaccustomed to.

So, what does “fitness” even mean? And is there more than one kind?

When you hear the word “fitness”, you probably picture someone who looks physically strong and athletic. But fitness can take many forms.

This includes cardiovascular endurance, which is how well your heart and lungs use oxygen to create energy.

There’s also muscular strength or your ability to move and lift objects in a single effort, for instance picking up a heavy box.

Body composition, or the amount of muscle you have relative to the amount of fat, is another aspect of fitness.

Read more: The dreaded beep test: outdated or still a valid assessment of your fitness?

Aerobic or anaerobic fitness. What’s the difference?

While we can understand fitness in many ways, exercise scientists commonly break it down into two broad categories.

Aerobic fitness refers to your ability to use oxygen to create energy. This allows you to physically exert yourself for longer periods of time, for example, running a marathon.

Researchers assess aerobic fitness........

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