Training | POSTED March 23, 2023

The Four Pillars of Fitness: Intensity, Volume, Frequency and Exercise Selection

As you settle into Ivy Training you might hear us mention unfamiliar terms. Our goal is to simplify the language used when discussing health promoting habits, behaviours and training. What follows will be an overview of four important concepts covered in training, what we refer to as the four pillars of fitness. These are Intensity, Volume, Frequency and Exercise Selection. Today’s discussion will not dig into the weeds of exercise science and maximising performance. Instead, this will be a brief, evidence-informed overview relevant to someone looking to become fitter, stronger and healthier in a personal training context.


The first of the four pillars of fitness is intensity. Intensity and the term intensiveness often get confused. Specifically, intensity refers to the load on the bar relative to an individual’s estimated 1 repetition max (% of e1RM). Intensiveness refers to simply how “hard something feels”. You can have an exercise that feels hard yet low intensity. Low intensity sets should be taken close to failure to be challenging. The crossover of intensity and intensiveness is proximity to failure

Proximity to failure refers to how many more repetitions an individual could perform with an exercise at a given weight before being unable to perform any more. If you are lifting a high intensity load, the total rep count will be lower and vice versa. For instance, 5 reps at 81% would have a similar proximity to failure as 10 reps at 68%. In both instances, the sets are about 2-3 more reps shy of failure.

To neatly compare intensity, intensiveness and proximity to failure, we use the terms RPE and RIR. RPE stands for Rate of Perceived Exertion and RIR stands for Repetitions in Reserve. We have used a graph below to show the relationship between the terms and flesh out the details more. In the graph you’ll notice the phrase “bar speed” which can also be termed “velocity loss”. This is a nice visual analogue to effort.

Try it yourself – do a set of push-ups and push as hard as you can before failing, you’ll notice those last couple of reps are an absolute grind! “Bar speed” slows as the effort required increases.


Volume in its simplest form refers to the amount of work done (whereas intensity is the magnitude of the work). It can be calculated as the number of repetitions performed for an exercise, muscle group, movement or session. However, without a magnitude, the volume in isolation isn’t a very useful metric. Volume does nothing to describe the stimulus of the work done.

For instance, for those who have already developed an aerobic base, running won’t build muscle. However, if we were to count “volume” while running you would accumulate thousands of reps! This doesn’t mean it’s “effective” as a stimulus. Volume is only useful to consider when the work is sufficiently intense to impart a mechanical stimulus onto the target muscle(s).

Therefore, when magnitude is considered, volume can be a useful parameter. For example, if I just told you a program had a High Bar Back Squat volume of “30” it could mean the following: 10 sets of 3, 3 sets of 10 or 6 sets of 5. Each of those schemes can stimulate muscle growth with the correct intensity. Although performance outcomes may vary. Exercise volume and strength adaptations exhibit a graded dose-response relationship. This means up to a point, more productive training produces better results.

We can’t give exact recommendations but 2-3 sets for each major muscle group, at the appropriate RPE is a reasonable start. From there we use soreness, fatigue and progression (or lack thereof) as an indicator of either too much or too little volume.


Frequency describes the number of training sessions performed per muscle group or movement in a given period of time. The time frame most often used is 1 week, typically termed a “microcycle”. As frequency increases for a particular movement or muscle group, training volume can increase. The simplest way to consider this is that frequency is a function of volume. That is, a higher frequency allows for more effective training volume. Too much work in one session can negatively attenuate the training stimulus.

If strength performance is more important than muscle growth and general health, a higher frequency may be ideal. This is due to allowing for fatigue management and hitting each lift fresh. Consider the following thought: would you feel most fresh performing 3 sets of bench press three times a week or 9 sets in one day?

We argue that frequency relies upon volume and intensity. Although, personal circumstance should be the deciding factor. For instance, some of our clients enjoy cross-training with activities such as running or swimming. Distributing training volume per muscle group across multiple days can potentially offset delayed onset muscle soreness and therefore, not interfere with other activities. In other instances, we might be trying to really increase the size of a certain muscle group and therefore, it’s more efficient in time-constrained sessions to prioritise that muscle-group within a session.

Exercise Selection

Exercise selection is a bit of a paradox. For instance, it can be unspecific and effective but also at times needs to be very specific. Here’s what I mean: If you were to compete in Powerlifting, you HAVE to Squat, Bench and Deadlift. I mean… that’s the sport! Yes, your intensities can at times be low (for higher volume work) or high (for strength developing and peaking) but you’ve always got to Squat the very least! 

For the purpose of general health and fitness, we believe exercise selection should be about:

  • General transferability
  • Training large amounts of muscle mass
  • Using a long range of motion
  • Exercises that have potential to improve over the long term

Ultimately training resources are NOT infinite – we have to make decisions with our time, resources and allocation of effort and therefore, there will simply be better or worse decisions to make in that regard. Moreover, we simply have to start somewhere! At Ivy Training we believe that teaching people a good foundation of barbell strength training will set up a lifter in the long term. This will include Squatting, Bench Pressing and Deadlifting (and/or variations of those movements) as they tick all the boxes discussed above. As time goes on, our clients will have a more robust history of training to draw upon and make decisions about which exercise seems to suit them best.


Training variables should aim to eventually be individualised. The four pillars of fitness: Intensity, Volume, Frequency and Exercise Selection should be appropriate to the individual, their physical, environmental and psychological resources and their goals. Importantly, an individual does not outpace their coverage by working at any level of the variables they are not yet accommodated to.

We hope you found this brief overview of the four training variables useful. A simple way to remember these variables is that how often, how hard and how much it is that you train a specific thing, should be related to your schedule, goals, preferences, and trainability. At Ivy Training we aim to provide you with the most suitable option for your training.