My latest post is surrounding what is intensity factor (IF). Another cycling metric my Garmin connect app reports to me and I historically ignored. But you shouldn’t ignore it. This will help to explain what the metric means, how it is calculated and how to use it. Improve the quality of your cycling training using Intensity Factor. It follows an earlier article on normalized power that has been very popular since publication.

Normalized power chart

My reason for wanting to understand this was following an injury from increasing my cycling training. I strained my left knee and I it coincided with me doing more hill work on my turbo trainer. From here I started looking into Intensity Factor and a wealth of other metrics to try and figure out how I injured myself.

Content Guide

What is Intensity Factor?

Intensity Factor measures how intense a workout is. Okay maybe I have over-simplified it. Intensity is a relatively subjective term. Your IF score is measuring the intensity relative to your FTP. So, this is not just a feeling to attribute to your workout. It is a quantitative value that an online training app such as Garmin Connect can calculate. Intensity Factor in this context is only relevant to cycling training and racing.

Where to find your IF scores

If you have completed a cycling activity using any form of power meter you can retrieve an IF score. The power meter can be on your bike or alternatively from a smart turbo trainer. When you complete your ride and the cycling data is gathered you can then look up your Intensity Factor score.

If you are looking for a smart turbo trainer read my recommendations on the 5 best turbo trainers for 2024.

Indoor Cycling turbo trainers

How is Intensity Factor calculated?

I have not been calculating my IF score. Nor am I recommending you try but the following explanation helps explain the logic so you can understand the science behind what you see. To calculate IF, you divide your workout’s Normalized Power by your Functional Threshold Power value. A workout with a normalized power watts score equal to your FTP will have an Intensity Factor of 1.0. Essentially it is about seeing how close to your FTP are you training or indeed training beyond this score.

What is a good Intensity Factor Score?

IF was designed to help understsnd the difficulty of a cycling workout. The higher the score then the more intense the workout. So, as I said I started researching this after an injury. Having injured my knee I could look into what my intensity factor scores were. This is where defining what a “good” intensity factor is subjective. A higher score in my case resulted in buggering up my knee. Too much hill work without enough of an increase in watts over time for me.

Power ratings with Intensity Factor IF score of 1.027

The thinking behind IF is that 1.0 or higher is your target. The higher the number, the more intense it’s likely to have been. IF measures intensity against your FTP (the power you can generate for an hour). Therefore, this metric is most useful for one-hour training sessions instead of shorter or longer sessions.

How should you use it in cycling training?

If you are changing your cycling training then using IF is a good measure to avoid injury as I experienced. If I had tracked it more closely I would have included some lower intensity sessions as I build up my wattage.

If you are riding at an IF score of more than 1.0 every time either your FTP needs updating or you are pushing your body too hard. Some sessions above 1.0 are a good stress test on your body but doing this 2 or 3 times a week risks injury and setting you back. Your knees are a particular area of weakness you can be risking by this kind of training.

I also think if you experience an IF above 1.0 regularly it is worth considering a retest of your FTP. As IF uses FTP as a metric if this is wrong your IF is wrong. So, don’t sit on an FTP score recorded 2 years ago. It is well worth retesting your FTP at least every 6 months.


Having founded Trivelo in 2015 after many years competing in triathlon Billy continues to enjoy cycling and triathlon. Founder Billy enjoys road cycling and mountain biking for some adventure. Generally a fair weather cyclist who come the winter months retreats to the turbo trainer!


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