Coggan’s Physiological Adaptation Chart

I hate to ask, but I’ve tried searching and still haven’t found a good explanation of how to read the chart or maybe I am too dumb.

I understand the overall what the chart says but I don’t know how your supposed to read it.

Thank you.



From left to right are training zones ordered by intensity (exercise stimulus)
From top to bottom are components of exercise physiology (result)

The number of x indicate how much one of the components is changed by training in that zone (effect size)

Happy to answer because I really like this chart.

For example you don’t have to train at VO2max intensity (stimulus) to improve your VO2max (result). And training at tempo has also many positive benefits.


Boy this chart burned many, including me. No brainer to ride just SS or Tempo. Right?
We need to add also stress load and needed recovery time columns to these tables.


Arguably the worst and best type of colons.


pun possibilities are endless with this one. Better not to go down that hole.


Trying to do sweet spot 2x20 two to three times per week certainly burned me out and kept me fatigued as a non-supplementing masters athlete. It may work well if in your 20’s or early 30’s.


Thank you for the answer! I didn’t know if there was something more to the x’s.

At that time, SST was fashionable, but now many athletes train POL. There are various opinions about the placement of x in this table. And, it would have been better if sustainable time for each zone was included.

It would be great if that chart also took duration into account. You can train at endurance pace for many hours, and still recover fast. But most people cannot do more than 2-4 x 20min at threshold, and would need substantial recovery. So how much time at endurance pace would you need spend before you achieve more than a threshold workout etc

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This is an interesting chart. As someone using TR, it seems to validate the sweet spot focus inherent in the plans. However, how does this mesh with the supposed gains of the “superior” (if you have the time) to train polarized? It seems the z2 adaptations are comparatively low

… but you can do a lot of it without hitting the issues around plateauing / fatigue / burnout that you take your chances with when you try to replace it with a lot of sweetspot.


As others have stated, this chart shows the ‘benefit’ of training at various exercise intensities. It is not showing the ‘cost’. You need to weigh both together to establish a function training plan.


A key part of the chart is the word “expected” in the title. The chart in the original book was very interesting for generating discussion and the authors (and others) used it to talk up SST. I have version 1 of the book but am now curious if the chart has been updated in later versions and re-writes and how well supported the data shown are. e.g. has data emerged to support the expectations.

FWIW, I think the SST proponents have added quite a bit to the training discussion. There is no doubt that 1-2 threshold (or SST) workouts each week can help an athlete hit strong FTP numbers. That said, for myself, while a block or two of SST/Threshold is a great sharpener, I do much better over longer periods focusing on mostly Z2 with one hard day (Threshold or SST workout or time trial race) every 7-10 days. My power numbers at race pace are just as good on Z2 training while my recovery, enthusiasm and ability to repeat day after day and be consistent are much better. Everyone is different though so best to try different programs and find your sweet spot (pun intended)


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The 2nd and 3rd editions of Training and Racing with a Power Meter have the same table of expected adaptations, and no column for sweet spot:

“Table 3.2 lists the primary physiological adaptations expected to result from training at each level, although these will obviously be influenced by factors such as the initial fitness of the individual, the duration of each workout, the time taken between each interval effort, and other factors.”

The guy that coined the term “sweet spot” is Frank Overton of FasCat Coaching. Going back to duration of workout, his sweet spot training plans will have you doing a lot of zone2 endurance work. The intro of some FasCat podcasts is a Frank soundbite “I was always an advocate that you could accomplish more with sweet spot training than riding in zone2 alone.” Emphasis more than “riding in zone2 alone” (the long slow distance or TR Traditional Base 1 concept).

Point being, there is value doing Zone2 Endurance work despite what you see in Coggan’s table. Maybe Inigo San Millan needs to do his version of expected adaptations.


For those new to this stuff who are curious, here is a podcast where Frank describes how SweetSpot concepts were elaborated. He gets into some of the points upthread regarding dose (time of a workout) fatigue, recovery and how to think about training.

The SST discussion starts around 12-13 minutes in and is a good story.

I’m a fan of ISM’s approach. Would be fun to see him address this!

as a starter, add two rows. Something like this:

Adaptation Zone1 Zone2 Zone3 Zone4 Zone5 Zone6 Zone7
Recovery Endurance Tempo Threhsold VO2max Anaerobic Neuromuscular
Glycogen sparing, increase fat as fuel + ++++ +
Lactate clearance ++++ ++ ++ ++

or something like that.

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Yeah, the original chart didn’t include sweet spot, so imagine asking the questions about “Why ever ride zone 2? why not just ride threshold every day?”

The answer is the same as when you include the sweet spot column.

I kinda hate this chart because it’s the reason we get people on MV plans asking if they should substitute a tempo ride for the zone 2 ride between threshold interval days because MOAR PLUSSES.


I mean its not really Coggan’s fault that people take it out of context. Like if you have the choice of only 2 rides in a week, 2 tempo rides is better than 2 Z2 rides of similar duration, but if you’re riding 20 hours in a week you might not need any tempo

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Or even need this chart.


I don’t blame Coggan at all. It’s just that this gets waved around like you said - without context - and it makes it harder to explain to people why you do certain things. “This chart shows I should ride SST all the time!” Sure, go right on and do that.