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Real conversations with people doing the work — in movement, in thought, in life.
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LVL UP Experience
Mastering Running Intensity, Lactate Thresholds, and Zone 2 Training
Show Notes: Mastering Running Intensity, Lactate Thresholds, and Zone 2 Training
In this episode, we dive into the science and practical application of running intensity, lactate threshold training, and the role of Zone 2 training. Drawing from the work of experts like Dr. Stacy Sims, Dr. Peter Attia, and Dr. Iñigo San Millán, we explore how to improve endurance, build metabolic health, and train smarter for performance and longevity.
YouTube References:
Dr. Iñigo San Millán Channel
Peter Attia MD Channel
Topics Covered
Training Intensity Zones
An overview of the five training zones and how each impacts your performance:
Zone 1 (Recovery): Easy effort for active recovery
Zone 2 (Aerobic Base): Builds mitochondrial capacity and endurance
Zone 3 (Tempo): Improves aerobic threshold
Zone 4 (Lactate Threshold): Boosts speed and stamina
Zone 5 (VO₂ Max): High-intensity for peak aerobic capacity
The key takeaway: most endurance training should happen in Zone 2, with strategically placed high-intensity sessions.
Zone 2 Training — Science and Benefits
Zone 2 is the highest intensity where lactate remains under 2.0 mmol/L — typically 60–75% of your VO₂ max, or the point where you can still speak in full sentences. Benefits include:
Improved mitochondrial efficiency
Increased fat metabolism
Better insulin sensitivity
Stronger aerobic base for performance and longevity
Dr. Peter Attia recommends 3–5 hours per week for health, and 7–10+ hours for athletes. Lactate measurement or 65–75% of max heart rate is a helpful guide.
Sweet Spot Training & Lactate Thresholds (LT1 & LT2)
LT1 (aerobic threshold) aligns with the upper end of Zone 2. LT2 (anaerobic threshold) is closer to tempo efforts. Sweet spot training falls between these thresholds:
Enhances lactate clearance and stamina
Ideal for tempo runs or threshold intervals (e.g., 3 x 10 minutes)
Balances volume and intensity for sustainable gains
The 80/20 Rule for Smarter Training
The 80/20 principle suggests that 80% of your training should be at low intensity (Zone 2), and 20% at high intensity (tempo, intervals, VO₂ max). This method:
Reduces injury risk and overtraining
Promotes consistent progress and recovery
Is widely used by elite endurance athletes
Example week:
Monday: Easy Zone 2 run
Tuesday: Hard interval or tempo session
Wednesday: Recovery or cross-training
Thursday: Sweet spot or moderate effort
Friday: Recovery run
Saturday: Long Zone 2 session
Sunday: Rest
Stacy Sims on Women and Training Intensity
Dr. Stacy Sims highlights important differences in how women respond to training. Key insights:
Women benefit from strength training and HIIT more than excessive endurance work
Align hard efforts with the follicular phase of the menstrual cycle
Post-menopause, increase strength and intensity to maintain muscle and metabolism
The bottom line: avoid too much Zone 3 work, and personalize intensity based on physiology.
How Much Zone 2 Do You Need?
For general health:
Minimum: 2–3 hours per week
Ideal: 3–5 hours per week
For performance:
Amateur athletes: 5–7 hours
Competitive athletes: 7–10 hours
Elite athletes: 10–15+ hours
Aim for at least 3–5 hours of Zone 2 training per week to build a strong base and support long-term health.