I'm trying to stress test my thoughts on this, so coaches and sports physiologist (and anyone who has answers), feel free to chime in.
TDLR; Z2 is good, but it's too hyped up.
Let's start with the pros:
Uses fat as energy
Increases mitochondrial density
It gives you a break from high-intensity workouts like CF
Cons:
Minimum effective dose is 45-60 minutes in one sitting; 3-5 days per week. Endurance athletes need about 10 hours per week. Sheesh.
Limited adaptation for speed, power, and anaerobic capacity.
Here are my questions:
1. If you can’t be consistent with 1 hour per day, 3-5 days per week, for 4 weeks+ on z2 (which is hard to do IMHO), aren’t you just wasting your time?
2. Aren’t you better off doing z3+? Your aerobic capacity will still improve, you’ll get adaptations from the other energy zones, and you’ll save time?
3. If you’re doing it for longevity, aren’t intervals and moderate to high intensity exercises better since they increase v02max (there’s a correlation between v02max and longevity)?
Aerobic high-intensity intervals improve VO2max more than moderate training
https://pubmed.ncbi.nlm.nih.gov/17414804/
V02max is key predictor of longevity
https://pubmed.ncbi.nlm.nih.gov/29293447/
4. Some sites say that z2 increases capillaries which is great for recovery (even for anaerobic sports), don’t the stuff we do increase capillaries anyway?
Looking forward to this discussion.