A GCN video reminded me yesterday of a major gotcha in zone training (ZT):
If you can't actually stay in Zone 2 when you're supposed to, maybe ZT isn't for you.
Many credible sources on ZT recommend a roughly 80/20% mix of Zone 2/4 riding. But to reap max benefit, you really need to
stay in Zone 2 (Z2) when it's Z2 time.
And many find that
very hard to do in practice, myself included. Oh, so easy for me to keep straying into Z3, and I'm by no means alone in this.
Problem is, if you indulge in Z3 or Z4 for even a few minutes, it could take your metabolism 30 minutes to return to the state actually targeted in Z2 riding. If you're committed to ZT, 30 minutes of Z2 time is a lot to lose.
My main impediments to Z2 compliance are jumbled hilly terrain and insufficient discipline. It's easiest to stay in any zone on long straight, flat roads with no traffic interference. No such roads where I live, even on the coast. Gradient's constantly changing.
Having seen the mountains where @Catalyzt lives, I think terrain's going to be a major barrier to ZT for him as well.
As for discipline, not really looking for more discipline in my retirement. Z3 and Z4 can feel very good at times. Hard to resist when the mood strikes, and why should I? To me, the bicycle is first and foremost a fun machine.
Also hard to stay focused on an HR or rider power display when there are so many better things to see, hear, and think about on a bike.
@Catalyzt has a strong incentive to train right now. Question is how best
for him to do that. I'm thinking now that ZT may not be the answer.
As for me, well, I'm not training for anything. My TdF days are over. Just want to get stronger over time. Just can't see how I'm gonna stay in Zone 2 when I'm supposed to. So ZT's probably not for me, either.
However, ZT isn't our only option. The GCN videos I linked above make a very important point: Current research indicates that if you're not
already a highly trained rider, ANY effort in the saddle will be beneficial. For recreational riders, the shortest path to greater fitness may well be above Zone 2.
I take that as permission to exercise any way I want on the bike. Every ride has fitness segments already. Keep it fun, and I'll do more.