
The Zone 2 Trap: Are You Under-Training Your Clients?
Zone 2 is trendy, but for a client with 4 hours a week, it might be a waste of time. Here is when to prescribe intensity over volume.
Zone 2 cardio is having a moment. Thanks to Peter Attia and the longevity crowd, clients are asking for 45-minute incline walks because they want “mitochondrial efficiency.”
But here is the reality check: Your client is not a Tour de France cyclist.
They have a job. They have kids. They have 4 hours a week to train. If you fill 3 of those hours with Zone 2, you are failing them.
The Research: Volume vs. Intensity
A 2025 narrative review in Sports Medicine challenged the Zone 2 dogma for the general population. The findings were clear:
For time-constrained individuals, high-intensity training (HIIT) consistently outperforms Zone 2 for VO2max improvements and cardiometabolic health.
The “Zone 2 Magic” comes from volume. Elite athletes do it because they have already maxed out their high-intensity recovery. They add Zone 2 because it’s “free volume.”
Your client hasn’t maxed out anything. They are undertrained.
The Programming Protocol
Don’t let a trend dictate your programming. Prescribe based on the constraint.
Scenario A: The “Time-Poor” Executive
- Constraint: 3 hours/week total.
- The Fix: Polarized Training is out. You need Threshold Training.
- Prescription: 2x Strength sessions, 1x High-Intensity Interval session (Norwegian 4x4s or similar). They need a potent signal to the heart, not a gentle nudge.
Scenario B: The “Stress-Case”
- Constraint: High cortisol, poor sleep, “fried” nervous system.
- The Fix: Zone 2 is perfect here.
- Prescription: Use Zone 2 not for “fitness” but for “parasympathetic recovery.” It doesn’t tax the CNS. It gets them moving without digging the hole deeper.
The Bottom Line
Zone 2 isn’t “better” or “worse.” It’s a tool.
- Use it for recovery, for high-volume athletes, or for the untrained/obese to build a base.
- Skip it if your client needs maximum ROI in minimum minutes.
Be the coach, not the influencer. Prescribe the dose that fits the patient.
Primary Sources
- Salanova, M., et al. (2025). Much Ado About Zone 2: A Narrative Review Assessing the Efficacy of Zone 2 Training for Improving Mitochondrial Capacity and Cardiorespiratory Fitness in the General Population. Sports Medicine.
- Seiler, S. (2010). What is Best Practice for Training Intensity and Duration Distribution in Endurance Athletes? International Journal of Sports Physiology and Performance.