Thread · saved · Apr 22
Zone 2 vs. HIIT trade-off
If I only have 3 hours a week, zone 2 or HIIT?
Whalespan · consensus-weighted · 2 sources
Mostly zone 2, with one short hard session.
The 2023 zone 2 meta and the older Norwegian 4×4 trials converge on the same answer: VO2max responds best to a polarized mix — roughly 80% easy aerobic, 20% genuinely hard. With 3 hours a week, that's two 60–75 min zone-2 sessions and one 20–30 min interval session.
Sources
[1]
Zone 2 + VO2max meta-analysis
Sports Med 2023 · meta n=1,402
[2]
Norwegian 4×4 protocol
Circulation 2008 · RCT
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