Why This Works

• Continuous high-intensity builds sustained glucose disposal and lactate tolerance.
• Zone 2 base expands mitochondria and trains fat oxidation.
• Switching intervals repeatedly toggle between glycolysis (carbs) and fat oxidation; exactly what “metabolic flexibility” means.
• Sprint + endurance combo depletes glycogen quickly, then forces an immediate shift to fat as the primary fuel.

How to Scale Your Effort

• Continuous Lactate Run: ~90-92% max effort (~105-110% of your 5K race pace) • RPE 8.5-9/10.
• Metabolic Switching Intervals (work phase): 95-100% of your 1‑mile race pace • RPE 9-9.5/10.
• Zone 2 Base/Recovery Runs: 65-75% max HR • RPE 4-5/10.
• Sprints: 100-110% of your 1‑mile pace • RPE 9.5-10/10.
• My absolute pace reference: 6:00/mile for high‑intensity efforts, ~9:30-10:00/mile for Zone 2. Replace with your equivalents using the percentages/RPE above.

RPE quick key: 10 = all‑out; 9 = very hard; 5 = steady, speaking in short sentences; 3 = easy conversation.

Week 1

Day 1 – Continuous Lactate Tolerance Run

• Effort: 90-92% max effort (~105-110% of 5K pace) • RPE 8.5-9/10.
• My pace example: ~6:00/mile.
• Structure: 5-10 min easy warm‑up (50-60% effort) → 0.75-1.0 miles continuous at target pace → 5 min easy cool‑down.
• Metabolic focus: Sustained glycolysis, glucose clearance, lactate tolerance.

Day 2 – Zone 2 Base Run

• Effort: 65-75% max HR • RPE 4-5/10.
• My pace example: ~9:30-10:00/mile.
• Structure: 30-45 minutes continuous at Zone 2.
• Metabolic focus: Mitochondrial biogenesis and fat oxidation efficiency.

Day 3 – Metabolic Switching Intervals

• Work phase: 95-100% of 1‑mile race pace • RPE 9-9.5/10 (my pace ~6:00/mile).
• Recovery: 1 min moderate walk/jog • RPE 3-4/10.
• Structure: 5-10 min warm‑up → 6 rounds of 2 min hard / 1 min recovery → 5 min cool‑down.
• Metabolic focus: Rapid fuel switching, lactate clearance, insulin‑independent glucose uptake.

Day 4 – Rest / Active Recovery

• Walk, mobility, easy cycling < 60% max HR. Keep it restorative.

Day 5 – Sprint + Endurance Combo

• Sprint block: 8 × 20 sec @ 100-110% of 1‑mile pace • RPE 9.5-10/10 (my pace ~5:30-6:00/mile).
• Between sprints: 100 sec walk.
• Transition: 3-4 min easy walk.
• Zone 2 block: 20-30 min @ 65-75% max HR.
• Metabolic focus: Fast glycogen depletion → forced fat oxidation under fatigue.

Day 6 – Zone 2 Recovery Run

• Effort: Keep closer to ~65% max HR • RPE 4/10.
• Structure: 25-40 minutes relaxed Zone 2.
• Purpose: Aerobic base without compromising recovery.

Day 7 – Rest

• Optional gentle yoga, breath work, or additional walking.

Week 2

Day 1 – Metabolic Switching Intervals

• Repeat Week 1 Day 3.

Day 2 – Zone 2 Base Run

• Repeat Week 1 Day 2.

Day 3 – Continuous Lactate Tolerance Run

• Repeat Week 1 Day 1.

Day 4 – Rest / Active Recovery

• Same as Week 1 Day 4.

Day 5 – Sprint + Endurance Combo

• Repeat Week 1 Day 5.

Day 6 – Zone 2 Recovery Run

• Repeat Week 1 Day 6.

Day 7 – Rest

• Fully off or gentle mobility.

Progression & Adaptation

• Every 2-3 weeks: Add 1 additional interval round (up to 8 total) or extend Zone 2 by 5 minutes.
• Ceiling rule: Increase only one variable at a time-either intensity or volume, not both in the same week.
• Recovery markers: Morning resting HR, sleep quality, and how quickly your breathing settles after warm‑ups. If these trend worse, dial back for 5-7 days.

Safety & Form Notes

• Always warm up (5-10 min easy) and cool down (5+ min easy).
• Choose flat, safe surfaces for sprints and hard efforts. Prioritize cadence and posture over raw speed.
• If you’re new to intervals or returning from a layoff, start with 4 rounds on switching days and build up.
• When in doubt, undershoot intensity the first week; consistency beats hero workouts.

Apply This to Your Own Goals

Use the percentages and RPE to set your personal paces. If you don’t know your mile or 5K pace yet, go by RPE for two weeks while you build rhythm. As your fitness improves, re‑test a 1‑mile and/or 5K and update your targets.

Pair this running protocol with nutrient‑dense meals, sleep hygiene, and smart strength training to compound gains in insulin sensitivity and metabolic flexibility. If you want a deeper dive into building metabolic freedom, join my program: 30‑Day Blood Sugar Reset.