I think conventional wisdom is "zone 2 for fitness / endurance, zone 3+ for performance." The interesting thing about this meta-analysis is it's discussing "baseline cardiorespiratory fitness" which - as I understand it - does correlate with vo2max.
As I understand it you can increase vo2max with exactly the type of training you are describing. Long efforts at zone2 can improve vo2 max, but the best improvements involve training at higher zones.
I certainly remember all the stories / headlines "walking is as good as running for cardiovascular health" etc which support the "just train zone 2" approach, but this study seems to me (a layperson) to contradict that.
Can anybody who is more versed in the research chime in? Does this study suggest that HIIT could reduce all cause mortality by improving vo2 max which improves baseline CRF (which is the value this the meta-analysis actually examined)?
V02 max is correlated with good health outcomes precisely because it's a proxy for cardiovascular health and fitness. Seeking to improve V02 max with hacks for health benefits is like trying to improve grip strength (a proxy for strength) to improve health.
You can sustainably improve your cardiovascular health by just slowly increasing your volume of work done at 120-150 bpm over time. Say start with a program like Couch to 5k, then slowly add a day of light jogging here and there, adding 5 minutes here and there, until you're jogging 30+ miles per week.
If you want to more "optimally" improve your cardiovascular fitness, after building an aerobic base as above for 12+ weeks, you can introduce a high intensity session to get some of the unique benefits of those, but your low intensity steady state zone 2 stuff should remain at least 80% of your time spent endurance training.
As I understand it you can increase vo2max with exactly the type of training you are describing. Long efforts at zone2 can improve vo2 max, but the best improvements involve training at higher zones.
I certainly remember all the stories / headlines "walking is as good as running for cardiovascular health" etc which support the "just train zone 2" approach, but this study seems to me (a layperson) to contradict that.
Can anybody who is more versed in the research chime in? Does this study suggest that HIIT could reduce all cause mortality by improving vo2 max which improves baseline CRF (which is the value this the meta-analysis actually examined)?