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Updated: Nov 24, 2022


So many riders attribute great importance to various numbers and metrics. It is our view that these numbers are only approximate indicators of an underlying physiological state. They must be used in conjunction with a regular, deep connection to your own body and how you are actually feeling on any given day. Read on if you want to know why it's not all about the numbers!


2 rides that look identical, with the same TSS score, can create dramatically different results: 4 hours smashing every hill full gas and freewheeling down the other side: 200TSS 4 hours controlled endurance riding at zone 2: 200TSS 2 hours controlled z2 well fulled: 100TSS 2 hours controlled z2 fasted: 100TSS 3 hours controlled z2 in 18 degrees heat: 150TSS 3 hours controlled z2 in 28 degrees heat: 150TSS

The actual toll these rides have on the body is dramatically different and therefore so are the adaptations: - The energy systems stressed are different. - The muscular fatigue is different. - The metabolic cost is different. - The rest period required is very different!

Not all TSS is created equally.

Avoid upping the power on an endurance ride in attempt to meet a TSS target. Learn to interpret how the TSS was made on any given ride and adjust rest periods accordingly.


CTL is a rolling cumulative TSS score. CTL is not how fit you are (despite what certain apps may say!), it is how much you have done. Not all TSS is created equally, therefore not all CTL is equal or comparable. You might have been flying with a CTL of 90 in 2021 and aim for the same number in 2022, but get a different result, why? The modality of creating TSS needs to be specific to the demands of any given target event. 90CTL created predominantly through intense FRC sessions will not prepare you well for a long endurance race, you will be far from race fit.


A metric commonly used for measuring “race readiness” and ideal training range. “I’m +5 TSB so I’m ready to train hard” Maybe, but does this number account for the late night you had, the stress at work, the long day on your feet, the house move? We only have one battery and all these stresses are draining it, but many of them are not shown in your TSB score. Your physiological state at +5 TSB can be totally different month to month. How race ready you are at +20 TSB can be totally different month to month, depending on how the TSS that created the adaptations was accumulated.

“My Whoop says I’m tired….”

The market is flooded with tech ready to tell you how tired you are, how fit you are, how happy you are, how hungry you are etc.

But, as coaches we’ve seen power PB’s set when a given app has suggested the athlete is at rock bottom, and vice versa.

The human body is a vastly complex network of about 30 trillion cells, it's unlikely these can all be represented in one number…take your Whoop score with a pinch of salt.


CTL, TSS, TSB and ATL might be good approximate indicators of a certain physiological state, but the most important indicator is how you actually feel.

Rate of Perceived Exertion (RPE) is infinitely more significant than any number on Training Peaks.

-eg does 200w feel like z2, if not, why not?

- If it feels harder, then ride easier in order to drive endurance adaptations and avoid unplanned fatigue.


-Even if self-coached, comment on all your rides as if you were talking to a coach.

-Read these comments at the end of each month and advice yourself as if you were advising a training partner or close friend.

Listen to your body, it is the most valuable bit if tech you will ever own!

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