Practical application of the Fitness & Freshness chart in training

You’ve become a Strava premium subscriber and you’ve come across the Fitness & Freshness chart (the FF chart). It’s a fancy chart, but you’re confused as to what the chart really represents and how you can use it to improve performance. In my opinion, the FF chart is the most useful Strava feature for improving your performance. I see the Strava segments as a great tool, a motivator to push you in hard (breakthrough) workouts, but the FF chart is the one that helps you improve, the one that tells you when you should pust as part of your structured training strategy and the one that signals you when are you properly rested to achieve your segment PB or even KOM.

The basics

The Strava FF chart and the WKO’s/TrainingPeaks’ Performance Management Chart (PMC) are equivalent tools, which only differ in their names and terms used. They all based off an impulse-response model developed by Dr. Eric W. Banister in 1975, which was later applied to cycling by Dr. Andy Coggan. That being said, if you are swapping from or just comparing one tool to the other, note that the below terms are interchangeable:

Suffer Score = TSS (Training Stress Score)

Fitness = CTL (Chronic Training Load)

Fatigue = ATL (Acute Training Load)

Form = TSB (Training Stress Balance)

In order to calculate the Fitness, Fatigue and Form values, Strava and WKO/TrainingPeaks first calculate the Suffer Score (Strava) or Training Stress Score (short TSS, used by WKO/TrainingPeaks) of each workout you make. A Suffer Score Score is basically a numeric value of the workout effort. The longer and the more intensive the ride, the higher the Suffer Score. A Suffer score of 100 is equivalent to you riding as hard as you can for 1 hour. Depending of the Suffer Score value, you should allow some time to your body to properly respond to the stress, induced by a workout. You should allow your  body the following recovery periods, depending on the workout Suffer Score:
  • 0-125; full recovery in 24 hours (1 day)
  • 125-250; full recovery in 48 hours (2 days)
  • 250-400; full recovery in 72 hours (3 days) – you will need three days to recover
  • 400 and above; full recovery might take up to 5 days
After the tool calculates the Suffer Score for each workout in the previous 6 weeks, it models your current Fitness, Fatigue and Form based on Dr. Banisters’ impulse-response model. Whereas there is a complex mathematical model behind the Suffer Score, Fitness and Fatigue values, a Form value is nothing more than a difference between Fatigue and Fitness values (Fatigue – Fitness). In layman’s terms, Fitness tells you how much training you have accumulated in the last 42 days (6 weeks) and thus, what is your general state of fitness. Fatigue tells you how much training you have accumulated in the last 7 days and thus, how tired your legs are. Form takes into account you Fitness (general state of fitness) and your Fatigue (tiredness) and tells you if (when) you are ready to perform at your best.

Shortcomings of the Fitness & Freshness chart

Even understanding the above, the values in the FF chart alone tell you nothing. You are probably still wondering whether the Fitness value of 65 is good or bad? Can you race successfully with a form of -4? And should you do I hard workout with a Fatigue of 30? Before I give you the guidelines and answer the above questions, you should note the following:
  • The FF chart is only accurate if you’re uploading all your workouts to Strava/WKO/TrainingPeaks.
  • The FF chart only takes into account the physical stress and disregards other important factors such as mental stress, sleep and nutrition, which might seriously impair (prolong) the recovery process. It also assumes that we (young, old, men, women etc.) all recover at the same rate. Even though the FF chart is telling you that you have properly recovered and that you are ready for a hard workout, you might have had a few stressful days at work, a bad sleep or you’ve just gone through a painful family matter. In values on the FF chart don’t correctly estimate your body’s physical state and you should in this case rely on your body’s signals. If you are feeling tired, don’t try to complete a hard workout, because your body is not able to process the additional stress and you will not achieve the physiological adaptations you are seeking (i.e. improved performance). If you try to do a hard workout, you most likely won’t be able to complete it as expected, which will only put you in an even worse state of mind. And aren’t you training because you want to improve and feel better after training? Because you want a training to relieve a mental stress and not add even more to it? Instead, take a day off or make some easy rides until the matters settle down (usually within a few days without extra stress, proper rest and nutrition) and you feel mentally ready to take on the more demanding workouts again. That being said:
Trying to improve the FF chart Fitness value without paying attention to your body will impair your actual performance (even though the FF chart Fitness value will rise). Doing so is shortsighted as you will be soon forced to decrease your training load due to excessive Fatigue (though not reflected on the FF chart). You should foremost pay attention to your body signals and take the FF chart values only as a guidance.
  • The Fitness and Fatigue values only represent the training impulses and don’t take into account the impulse type. We know that different impulse types lead to different physiological adaptations. Therefore, people training different sports develop different muscles. A runner and a cyclist with the same values will achieve drastically different results in the other discipline, despite identical values. Even within the same sport, different impulse types lead to different physiological adaptations (e.g. a peak power or power at threshold); a sprinter and a climber might achieve the same Fitness, Fatigue and Form values, but they will only be competitive in their own fields (i.e. sprinting or climbing). Thus, the individual values cannot be compared between individuals and two individuals with the same scores might perform drastically different on any given day.
  • The guidelines below are based on my observations during training and racing. If you find that your body responds differently, make proper adjustments to the values.

Practical application

First a brief introduction so you can better interpret the below values. I am an amateur cyclist and a triathlete with more than 10 years of experience in training and racing. My form has been declining from 2014 due to my work obligations and I gained some weight. In March 2018 I weighted 86kg and I had a Functional Threshold Power (FTP) of 290W. I started training again with my primary goal of weight (fat) loss and secondary goal of improving my FTP. Four months later (June 2018) I weighted 80kg and achieved an FTP of 338W (4,22W/kg). The below guidelines reflect my observations in this four-month period of structured training. I am still monitoring my Fitness and Fatigue values and in case I notice the below values to be inaccurate with higher Fitness, I will update this article accordingly.

Fitness values

  • Joe Friel recommends increasing your Fitness by 5-8 Fitness points per week. I could only sustain an increase of 3 Fitness points/week during training weeks (excluding recovery weeks!) and I managed to increase my Fitness from 27 to 62. If I increased my Fitness more, the following week suffered and the rate of Fitness increase was down to 3/week.

Fatigue values

  • I could complete my hard (breakthrough) workouts with Fatigue up to 63 (and Form of -18). If my Fatigue values were higher, I couldn’t complete the training as planned or I did, but I was way too exhausted in the following days, which interfered with my regular training routine (I had to rest for a few days).

Form values (recommended by Joe Friel)

  • For your peak training period, you should maintain your Form in the -10 to -30 range.
  • You can only push your Form below -30 once every 10 days.
  • During the recovery weeks, you should aim to increase your Form to -10 to +5.
  • You should aim for a Form value of -5 to +20 for an A-race.
I recommend you to start training using the above guidelines and to regularly monitor your Fitness and Fatigue values on the days preceding the hard workouts. This process requires experimentation on your side. You should try to do a hard workout on the days when your Fatigue value exceeds the above values. If you still manage to pull out a great workout that means that you can do a hard workout even at greater Fatigue. The contrary can also be true. If you can’t complete a hard workout despite your Fatigue values being lower than the above, you should train accordingly and update your upper Fatigue value so that it reflects the ability of your body to complete a quality workout. You can also experiment with the Form value, just make sure that you are experimenting on your B or C-level races. You can try to compete in different races with different Form values and see how you feel during the race. I would say that the feel during the race is more important than the overall result due to environmental conditions and also due to changes Fitness. I hope the new knowledge will help you improve at a faster rate. And don’t forget, if you found this article helpful, please share it with people who might also benefit from it.  

Written by marko