Originally Posted by
Carbonfiberboy
In the Friel system, VT1 is approximately but not exactly the boundary between zones 2 and 3. VT2 is the boundary between zones 4 and 5.
In the polarized system, zones 1 and 2 are separated by VT1. Zones 2 and 3 are separated by VT2.
The first link conflates the two systems. Early in the article, it states that the upper boundary of zone 2 is at LT, which approximately coincides with VT2 depending on how LT is defined. As I said above, in the Friel system, LT is the upper boundary of zone 4. The rest of the article than describes training in zone 2 as though it were in the Friel system, including a recommendation to train for 2 hours at the upper boundary of zone 2, which is obviously impossible and certainly is not an "endurance ride" in anyone's vocabulary. Zone 1 is not even mentioned.
The second link is a mishmash of confusing verbiage. For instance
This after defining zone 3 as above LT. No one recommends this even in Friel's zone system. These are called junk miles.
Oh, I think something went wrong here, and quite possibly due to all the different Zone-definitions and LT-definitions. Probably my fault for not pointing out, sorry.
The articles actually use Coggan's 5 (HR-)zones; so their Z2 ends (roughly) at VT1. Their Z3 is (roughly) between VT1 and VT2, and their Z4 around VT2 and their Z5 above VT2.
However, where things get more difficult is their use of LT. They describe LT as the FIRST lactate treshold (when lactate in the blood rises but is still stable) , which again roughly coinsides with VT1. For the second treshold (at VT2) they use the term MLSS (above this point lactate accumulation is no longer stable and you muscles fatigue quickly).
I can imagine, being posted in this thread it can become confusing very fast, but with the previous mentioned knowledge they actually are not that far of of what you mention.
Where they
do differ is that they say that it is also worthwhile to train and ride in Coggan Z3 (polarized zone 2) because of the slightly different adaptations in that zone compared to below Z2. And I think that they are not very wrong with that. They describing it as "pushing" power-output up by riding below VT1 and then "pulling" it up by riding between VT1 and VT2.
Translating that further:
The end goal for building your base is the capacity to complete back to back rides in zone 3 over several days – with well developed endurance it should be possible to complete up to 3 x 3 hour zone 3 rides on consecutive days.
Means being able to ride between VT1 and VT2 for three consequtive days. (They note that it is actually very difficult.)
My personal experience so far is that just riding below VT1 and occasionaly above VT2 just misses out on adaptations that are also useful for my conditioning. Especially considering the time available to me to ride polarized (again
in my opinion and experience) just isn't as effective as training in all zones occasionally.
I hope you don't take this the wrong way CFB, I always find your posts very meaningful and informative, but I just think you misunderstood the site.