How often should you be doing Zone 5 training? | Iñigo San-Millán, Ph.D. & Peter Attia, M.D.

Key wellness strategies & training guidance (Zone 5 / high-intensity + Zone 2 focus)

The “four pillars” of exercise (framework)

• Stability
• Strength
• Low-end aerobic (linked to mitochondrial efficiency)
• High-end aerobic (linked to peak aerobic capacity / anaerobic performance)

Why Zone 5 (VO₂ max / high-end aerobic) matters—but doesn’t need to dominate

• VO₂ max is strongly correlated with longevity, so maintaining it is valuable for health.
• However, high-end aerobic is the least enjoyable and hurts more.
• For non-competitors, the goal is health + metabolic function, not athletic results.

“Sustainable dose” principle

• The most effective exercise dose is:
  • Effective (supports mitochondrial/metabolic health)
  • Sustainable long-term
• Very high-intensity training isn’t sustainable for everyone in large volume.
• Combining exercise with extreme diets is especially not sustainable.

Mitochondria + glycolysis: train both, efficiently

• Aging and sedentary behavior reduce mitochondrial function.
• Aging also reduces glycolytic capacity, which needs stimulation.
• Strategy:
  • Use Zone 2 regularly as the base to target oxidative/mitochondrial benefits.
  • Add high intensity at the end of Zone 2 to also stimulate glycolytic capacity.
• Avoid doing high intensity first or inserting it in a way that disrupts the base work (see ordering below).

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Practical programming tips (what to do with limited time)

Common clinical-style prescription for Zone 5 (VO₂ max)

• 4×4 protocol
  • 4 minutes hard
  • 4 minutes recovery
  • Repeat ~4–6 times
  • With warm-up and cool-down, a little over an hour total

A simpler “add-on” approach for people who can’t do many sessions

If you’re short on time (e.g., only ~1–2 hours per session):

• Do Zone 2 for most/all of the workout (often targeting ~4–5 sessions/week if possible).
• At the end, add a single short Zone 5 effort (example mentioned):
  • ~5-minute hard interval (with willingness to repeat when you’re fresh enough)

This aims to improve:

• Mitochondrial/oxidative system (from Zone 2)
• Glycolytic system (from the end-of-session hard interval)

Order matters (what not to do)

• Recommended:
  • Zone 2 first
  • Zone 5 last
• Avoid:
  • Doing Zone 5 before Zone 2
• Reasoning provided:
  • High-intensity earlier can create hormonal responses, high lactate, and can interfere with downstream fat metabolism processes.

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Understanding training “time in zone” vs actual physiology

• “I rode for 45 minutes in Zone 2” may be misleading if intensity repeatedly rises/falls.
• Example concern:
  • Power/HR oscillations mean you may actually be spending time in multiple zones rather than truly holding Zone 2 continuously.
• Key idea:
  • Dedicated energy-system training matters more than the rough total minutes on a zone summary.

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Metabolic mechanisms mentioned (why spacing/order helps)

• Lactate can inhibit lipolysis (fat breakdown).
• Lactate at higher levels may reduce activity related to fatty-acid transport (CPT-1 and CPT-2).
• High-intensity can raise cortisol-related stress markers, which is another reason to place intervals at the right time.

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Safety / disclaimer noted in the video

Content is for general information and not medical advice. No doctor-patient relationship is formed; seek professional care for health conditions.

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Presenters / sources

• Iñigo San-Millán, Ph.D.
• Peter Attia, M.D. (context: Peter Attia / blog and podcast; also includes a standard podcast medical disclaimer)