What is the F.I.T.T. Principle?

Today we’ll explore the acronym of F.I.T.T. in a number of ways. We’ll start by defining the F.I.T.T. principle as weekly we hear trainee FITPROs asking…

” What is the F.I.T.T. Principle, I’ve heard it lots of times but no one has ever explained it?”

Then we’ll explore various ways in which a FITPRO can and should be using it…. and why it’s important to do so. Plus make notes as you read and watch today’s revision video. And make sure you test your knowledge with the mock questions below.

Let’s start with the definition

What is the F.I.T.T. Principle?

The F.I.T.T. Principle is an acronym used to describe the physical activity.

All too often the F.I.T.T. principle gets thrown aside and seen as something basic. Or as something learned at level 2 fitness instructor and no longer relevant.

I want to be the first to say… the F.I.T.T. principle is the backbone of all your FITPRO planning.

Even though you might think it’s basic and you’ll never use it. I bet every FITPRO implements it daily without even knowing it.

And below we’ll outline why it’s so important plus give you options of how and where to use it.

Let’s start with breaking down the acronym of F.I.T.T.

Frequency – the number of days and sessions per week of activity.
Intensity – the measurement of total stress on the body. You could use RPE, heart rate, rep max, RIR, METS etc to illustrate this.
Type – the mode in which a person moves e.g. walking, Yoga, Strength resistance training.
Time – the total time duration per session and per week.

What is the F I T T Principle

Using the F.I.T.T. Principle in a client consultation

The first place to implement the F.I.T.T. Principle is in an early client consultation… perhaps your first meeting.

You can ask clear open questions to find out what the client’s current F.I.T.T. status is.

You could also ask about their previous F.I.T.T. Going back 3, 5, or 10 years. This allows you to plot a basic timeline of where activity stopped and started over the past 10 years. Plus add details of any major life events such as family, work, or injury.

This would give you a clear picture of their activity habits and how they got to where they are today.

Other questions arise from this including their activity likes, dislikes, and mode preferences. Plus you can ascertain why they stopped or when activity declined historically.

This would highlight what beliefs and priorities influenced any activity changes. For example, they might believe you can’t consistently train with a new and young family.

Or perhaps they injured their left knee whilst squatting, and have not returned to the gym for 3 years.

What is the F.I.T.T. Principle

Open Questions to Explore the F.I.T.T. Principle

To help you find these answers… you need to ask clear open F.I.T.T. Principle questions such as:

Frequency: This can be structured and non-structured activity.

Tell me about your week and where the activity falls? If we go back 3 years was your activity the same as today? What about 10 years ago, how was your activity different?
This gives you a clear picture of how often they are active throughout the week. Plus you’ll discover their training age as you ask questions about activity levels 3, 5, or 10 years ago.

Intensity – here you’re trying to find out how hard they push themselves.

Using a “Likert scale of 1 to 10” in your questions helps the client measure their efforts and justify their answers.
For example…How hard is each session on a scale of 1 to 10?
The client may say 7. You can now follow up by saying.
“7 out of 10 is quite high, why did you choose a 7 and not a 9?”
Another example could be… How out of breath are you whilst walking the dog?

You can follow up with further questioning about their route. Maybe the route changes due to time pressures, how they feel, or the weather… this could determine their intensity and their output.

Type – What’s the client’s preferred or current activity?

Here you get to learn what they like and dislike.
Often the client will tell you what they don’t like first.
You could explore any pre-conceived ideas and beliefs the client holds about activity. Or any past experiences that were negative.
This allows you to plan accordingly… making sure all future sessions don’t include activities they dislike. Or reinforce any past negative beliefs.

Saying that… we’re a fan of focusing on the positives of what the client does like and why. Now you can plan fun, safe, and effective sessions that the client can easily adhere to.

Time – How long does the client move for every week and every session? (or insert the activity you know they participate in).

Try and place an average amount of minutes spent on structured and non-structured activity.
You could also categorise time spent on each component of fitness, for example,

  • 60 minutes of cardio across 2x gym sessions (30 mins each)
  • 30 mins stretching across 3 days (10 mins each)
  • 120 minutes of resistance training across 2x gym sessions (60 mins each)
  • 70 minutes walking the dog across 7 days (10 mins each day)
  • Total 280 minutes of activity: 190 structured and 70 non-structured.

How to get more information out of your client?

Open questions are great, they can’t be answered with a simple yes or no. But they can be answered quickly and only provide surface-level answers.

A key phrase to help keep your client talking, opening up, and going deeper on their surface-level answers is…

Tell me more… (plus insert something from their previous answers)…?”

For example, Tell me more about how often you go to the gym? is it always every Monday and Thursday?

Try to dig for more information and find any anomalies. This is where you grow as a coach and find the missing link that will get the client their goal.

This keeps your consultation client-centered.

And you get to learn more about the client and dig deeper into their surface answers. All the time, this intrigue builds client/FITPRO rapport and trust.

Once you’ve collated your client’s answers… you can categorise them into the ACSM F.I.T.T. Principle guidelines.
Here you can ascertain whether the client currently meets the ACSM guidelines… or if they have done so in the past.
You could also highlight the client being biased towards one component of fitness.

For example, the client might just train strength resistance. Not valuing or prioritising other components such as cardio, flexibility, or motor skills.

Learning about your client’s past and current status allows you to plan smart.

Using the F.I.T.T. principle to plan effectively

The information gathered using the F.I.T.T. Principle allows you to ascertain the perfect starting point for your client.

Let’s assume the client’s goal is to improve their strength. To focus on particular lifts such as a clean and jerk.

The client’s current F.I.T.T. identifies them as only training strength resistance. In the hope, they will get stronger and perform better. His F.I.T.T. principle is:

  • F = 2 x per week
  • I = 6 Reps per set to overload
  • T = Free weights, Clean and Jerk and big compound moves
  • T = 50 mins each session

Let’s use this F.I.T.T. Principle for this case study client to see how it will influence planning…


It is a good rule of thumb to match the client’s existing frequency in the first couple of weeks. Then you can logically progress frequency over time. This case study only trains twice per week and so your first couple of weeks training together would match this frequency. Ideally, the frequency would be the first F.I.T.T. principle variable to change. The more we do something, the more opportunities the body has to adapt to a new stimulus.

You know he should be training more frequently… but if you increase frequency too quickly this could be too much too soon. A sharp increase in frequency can lead to:

  • increased DOMS or muscle soreness as the overall volume of training increases sharply
  • less rest in between sessions leading to poor recovery and increased chance of injury
  • more time committed to training, which changes the weekly routine considerably. This can affect work, nutrition, and relationship significantly. Client adherence is key, and this stress on routine can be the biggest cause of waining adherence.


This case study client reports doing 6 reps per set, which is the correct intensity for his goal. You may keep him at the 6 reps for a good few weeks of training, and just ensure that overload is truly being achieved.

You may also deem it inappropriate for the client to be training at 6RM, based on his past F.I.T.T. Principle, ability, and training age. In which case you could reduce the intensity by increasing the reps and lightening the load.

It is also key to note here, that intensity is not just about resistance. It may be that you want the client to increase the Range Of Movement to improve his Clean and Jerk, in which case ROM becomes the key intensity variable.


As you know, all components of fitness must be included. We can see that the client in the case study is only doing strength training with free weights. Although this is specific to his goal, there are many benefits from adding all components of fitness:

Cardiovascular: By challenging the heart rate maximally, the client challenges the Creatine Phosphate Energy System and Type 2b Muscle FIbres. This is the same adaptation that we require to get better at the Clean and Jerk movement. You could add a couple of short Cardiovascualr sessions per week doing high-intensity intervals, and see massive improvements in performance,

Flexibility: The client currently doesn’t do any stretching or flexibility sessions. You may do a squat assessment with your client and notice that the ankles and the hips have restricted movement. Stretching key muscles in this area will allow you to reduce compensations and rapidly improve performance in the Clean and Jerk.

Motor Skills: The client should include activity that challenges Agility, balance, and coordination as these will help improve the efficiency of movement patterns.


This is a great variable to gradually increase the overall training load over time, in small increments. For example the client might only be able to do 2 sessions per week, but his routine may allow for an extra 5 mins for each session. This creates a seamless integration into a routine and also benefits the client with more load and volume across the week.

Anatomical and Physiological Adaptation

Gradually and logically progressing the F.I.T.T. Principle variables allows for anatomical and physiological adaptation. It is this adaptation that creates the changes in the body associated with increased performance, reduced weight, faster speed, greater hypertrophy etc

It is our role as a FITPRO to chose the relevant variables and change them at the appropriate intensities to achieve the client’s desired goals.

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Test your knowledge with today’s F.I.T.T. Principle questions:

[NOTE: The answers are below the 3rd questions]

Q1: If your client swapped their yoga class for a walk, which variable of the F.I.T.T. Principle did they change?

A. Frequency
B. Intensity
C. Type
D. Time

Q2: How might a client increase the intensity of their session?

A. Reduce the range of movement
B. Increase the weight lifted
C. Reduce the weight lifted
D. Have more rest

Q3: What is a risk associated with increasing frequency too quickly?
A. Client adherence increases
B. Client adherence drops
C. Client has lots of time to recover
D. Client has less DOMS

Answers to the mock questions are :

Question 1= C, Question 2 = B, Question 3 = B

If you want more mock questions like this, then you can download more Free Mock Questions: DOWNLOAD NOW

Dedicated to More

Hayley “What is the F.I.T.T. Principle?” Bergman

Parallel Coaching

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