When I was in high school, I was first introduced to the idea of “fitness components”.

Essentially, the different qualities underlying what it means to be “fit” - which help determine our ability to do physical tasks.

Back then, they were divided into:

“Health-related” components: cardiorespiratory (aerobic) fitness, strength, body composition, flexibility; and

“Skill/performance-related”components: power, balance, agility, coordination, reaction time.

This distinction implied that some components mattered for health, while others were only important if you were an athlete or played sport.

Fast forward twenty years, and a lot has changed. We now know being able to produce power, maintain your balance, react quickly, and coordinate movement clearly matters not just for performing in sport, but for performing in daily life, too. Not to mention most of these are very closely linked to your risk of various chronic diseases and adverse outcomes like falls, fractures, and early mortality.

Which is why, after 40 years, the American College of Sports Medicine (ACSM) finally updated their fitness component model. There are now five components of physical fitness, without the previous distinction between those relevant for health or performance:

But I actually think the most useful part of this model isn’t the five components themselves.

It’s how interconnected they are - and how you can potentially cover most of them without making your exercise routine more complicated.

So, what are the five components of “fitness”?

1: Cardiorespiratory fitness - your ability to keep going

This is your ability to sustain physical activity without excessive fatigue.

Walking uphill, climbing stairs, or running around with your kids/grandkids all have a certain energy cost. The higher your cardiorespiratory fitness, the smaller the proportion of your capacity needed to meet those demands - and generally, the easier they feel.

Improving it means doing things that meaningfully challenge your heart and lungs. It doesn’t have to be formal “cardio” like running or cycling either - even activities like stair climbing can count when done with a little more intensity.

2: Muscular fitness - your ability to produce force

The ACSM now groups three aspects of muscular fitness together:

Strength = how much force you can produce

Power = how quickly you can produce force

Muscular endurance = how repeatedly you can produce force.

These determine your ability to lift, carry, climb, and get up - all essential components of day-to-day tasks. Power deserves particular attention because most daily tasks aren’t about producing as much force as possible (strength), but producing enough force quickly (power).

Resistance training is clearly an important pillar for improving muscular fitness, but how you train can influence whether the emphasis is on strength, power, or muscular endurance (more on that later).

3: Neuromotor fitness - your ability to control movement

This includes balance, agility, and gait (walking) speed in the new ACSM model.

These are all important for keeping you stable, such as when you’re navigating uneven ground or changing direction, and for allowing you to move quickly and confidently through your environment.

These qualities can be challenged through a variety of activities, such as balance exercises, single-leg exercises, hiking, sports, dancing, and plenty more.

4: Flexibility: having enough movement available

Flexibility is essentially the range of motion available to your joints.

But the aim isn’t necessarily to be maximally flexible - just to have enough movement available to comfortably do the tasks you want to be able to do.

Stretching is an obvious way to improve your flexibility, but it’s not the only way.

Contrary to a pesky and outdated myth that lifting weights makes you inflexible, resistance training (including free weights, machines, or Pilates) can actually improve flexibility (joint range of motion).

5: Body composition: what your body is made of

This broadly refers to the relative amounts of fat mass and fat-free mass (including muscle) in your body.

Practically, the two important things here are maintaining your muscle mass and avoiding excessive body fat - particularly visceral fat stored around our internal organs.

Resistance training is your go-to for increasing muscle mass, and while aerobic-type exercise is typically associated with fat loss, resistance training can meaningfully influence body fat levels too (alongside appropriate nutrition).

Now seeing the five components together might make you think you need to include 5 different types of exercise in your week.

But rest assured, that’s not the case.

The important part is these components overlap

These five components aren’t independent buckets, and in fact, the ACSM explicitly describes them as interconnected.

That’s good news, because it means the same exercise could contribute to multiple components at once.

Resistance training obviously targets muscular fitness and body composition, but depending on how you do it, it can also improve your flexibility, challenge aspects of neuromotor fitness, and even your cardiorespiratory fitness.

Aerobic training is of course your go-to for improving cardiorespiratory fitness. But it can also help with your body composition, improve your gait speed, and possibly your balance and muscular fitness depending on what you’re doing.

So instead of asking “how can I train all five components?”, the better question here is: “how many components can I cover with the exercise I’m already doing?”.

So, what can a “minimalist” approach look like?

Let’s start with the two big “rocks” - being resistance training and aerobic activity.

If resistance training is your starting point…

Just two full-body sessions per week can give you a lot of bang for your buck.

That’s especially true if you train most of your muscle groups using a handful of movements that involve pushing, pulling, squatting, and hinging.

Doing some of those exercises through a full range of motion can improve flexibility at those joints.

After building a base of strength with controlled movement, performing some movements quickly (or at least with the intention to move fast) can place more emphasis on power.

Then, including exercises such as lunges, split squats, or other movements with a narrower base of support can introduce more of a balance challenge.

Suddenly, you’re not just training strength - but also power, flexibility, balance, and body composition - all without adding another workout to your week.

And if you’re doing aerobic training only?

Your starting point here could be as simple as building some walking and other general movement into your week.

Depending on your current fitness level, many different activities could improve your cardiorespiratory fitness, so long as they meaningfully challenge your heart and lungs. It could be brisk walking, cycling, hills, swimming, running, or even going about your daily activities with more intent.

But the choice of activity can broaded the benefits too.

For example, brisk walking may challenge your gait speed (neuromotor fitness), and adding hills or stairs can increase the muscular demand (improving aspects of muscular fitness like strength or power). Doing some hiking or walking on less-stable ground could even improve your balance too.

Of course, aerobic training can’t completely replace the benefits of resistance training or balance training.

But the point is one type of training doesn’t necessarily train only one component of fitness.

Then, plug the gaps

Once you recognise the overlap between fitness components, it’s then about looking at what your current exercise routine covers, and what’s missing.

If you’re already walking regularly, perhaps adding some hills or stairs, or ideally resistance training, could boost your muscular fitness.

If you’re already strength training regularly, but don’t often challenge your heart and lungs, then adding some simple aerobic activity is the obvious gap.

Even if you’re doing both, there might be simple ways to tweak what you do to target other components like power, balance, or agility.

The key point here is plugging a gap doesn’t have to mean a new workout. It might mean adding a few minutes of more balance-focused (or less stable) exercises to your strength sessions, some faster movements to train power, or adding some hills or stairs to your walk or run.

And keep in mind that many recreational activities, like hiking, dancing, or racquet sports naturally train multiple components at once.

Sometimes, covering another fitness component might only require a few extra minutes (or a change in exercise), rather than add another hour-long workout.

You don’t need a perfectly balanced program

It’s important to reiterate you don’t need to maximise all five of these fitness components.

The ACSM makes it clear the importance of each really depends on the individual, including their current health, fitness level, goals, and the things they want to be able to physically do.

So, it’s up to you to think about what your current exercise routine already covers, and whether there are any gaps that might matter for the things you want to be able to do.

This new ACSM model might redefine what it means to be “fit”, but that’s not a reason to make your exercise program more complicated.

So my suggestion is to start with one (or ideally both) of the two big “rocks” - being resistance training and aerobic activity. Then look for simple ways to plug any gaps that might matter to you.

Remember: the goal is not to train five different components, but to find the simplest (and most sustainable) routine that keeps you fit enough for the life you want to live.

Thanks for reading!

Until next week,

Jackson

PS: I’d love to hear if this resonates with you, and whether there are any simple ways you could cover more bases with the exercise you already do.

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IMPORTANT:

The information contained herein is of general nature only and does not constitute personal advice. You should not act on any information without considering your personal needs, circumstances, and objectives. Any exercise program may result in injury. We recommend you obtain advice specific to your circumstances from an appropriate health professional before starting any exercise program.