I’m looking at my fitness chart and trying to correlate how I feel with what I’m seeing. In term of how tired I feel and how much energy I have, should I be looking at fatigue or form? It feels like the form line corresponds better to my feeling of tiredness. Right now, for example, I’m feeling more tired than I’ve often felt when my purple fatigue line has been much higher, while my form is really low which I think must explain it. But then why isn’t form called fatigue, and fatigue called something else?
Have a read here:
And make sure to read the other Guide topics. They explain quit a lot of your questions for starters.
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Due to trademark rights, Fitness, Fatigue and Form cannot be named what TrainingPeaks (trademark owners) call it, namely Chronic Training Load (CTL), Acute Training (ATL) and Training Stress Balance (TSB) respectively.
So Fatigue is your short term training load (the last 7 days), while Form is the difference between Fatigue and Fitness, the longer term training load (last 42 days).
As you work each day, you gain fitness and fatigue together. After 14-21 days, if you have worked hard enough to push beyond what you did previously (overload), you need to rest/reduce the training load to allow the body time to recover and adapt.
Because Fitness is measured over a longer period (42 days), the number doesn’t drop as quickly as Fatigue would drop when you’re in a recovery week. The formula (for the absolute calculation, not % of form) is:
Form = Fatigue - Fitness, The “balance” that TrainingPeaks refers to (TSB) is allowing the drop of fatigue (a negative value) or an increase from a negative number towards zero, or slightly positive.
But before it drops to zero, you want to start training again, so you’re not fully recovered. This also allows your body to continue to adapt to an increasing training load.
@MedTechCD has shared a link to the explanation of how you should feel relative to what the data says. To add to those posts, it’s important to keep a track of how you feel (daily), and then compare it to the chart. When you “feel” tired, have a look at the (Form) value on the chart, and see if there’s a correlation. Then see how long it takes to recover, and look at the (Form) value on the chart.
If you are not overloading your body over a 2-3 week period, you might not feel as tired as you would if you were training optimally. This is what some refer to as the “green” zone (green being the colour used to determine the optimal training zone), which shows your Form value between -5 and -30. By progressively overloading the body, you will see the Form number creep close to -30 (start of the red zone), which is shown as high risk. That would be the theoretical point at which you need to start recovery. Some might fatigue before reaching -30 and some after. This is why it’s important to track how you feel daily, so you have a subjective input to go with an objective input (data, plus other signs like HRV and resting HR).
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Thanks
Thanks. Super helpful. My goal is to gradually increase the distance I can run so that I can run a decent amount each week, with serious long runs on the weekend, without risking injury or overtiredness. This is less for the sake of fitness to be perfectly honest than just because I love running. But because my work reqiures a lot of mental energy and drive, I need to keep my fatigue at a minimum (I’m 60), so I’m trying to finesse it so that I can slowly increase distance without becoming overtired.
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