Originally Posted by terrymorse

So what's everyone's opinion about zone 3?

If you do a google search, you'll see it called the "grey zone" or the "mediocre middle". Not much love for zone 3 from the coaches.

The argument against zone 3 seems to be that it's not hard enough as zone 4 to elicit adaptation, but it is more fatiguing than zone 2.

I tend to do a fair amount of zone 3 on long climbing days, and it seems to improve my muscular endurance and the ability to spend more time just below my threshold.

On a weekly basis, I'm doing roughly equal amounts of zones 2 and 3. I figure that's decent training. Change my mind?