The Extramilest Podcast

#121: How to Build an Unstoppable Aerobic Engine (Even If Starting From Zero) | Scott Johnston

40 snips
Feb 28, 2026
Guest
Scott Johnston
Scott Johnston, endurance coach and co-author of Training for the Uphill Athlete, explains building an aerobic foundation. He covers aerobic vs anaerobic thresholds, how long aerobic gains take, and testing methods for your first and second thresholds. Practical plans include zone-two volume, caution around ramping load, and when double-threshold days make sense.
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ANECDOTE

Dramatic Early Gains For Aerobically Deficient Runners

  • Scott described athletes who started with 12–13 minute-mile aerobic threshold speeds and improved to 9–10 minute miles within months.
  • These examples show big aerobic gains are common when athletes are initially aerobically deficient.
INSIGHT

Narrow Thresholds Mean Bigger High-End Aerobic Load

  • Improving aerobic threshold speed moves the first threshold closer to the second and expands usable low-intensity zones.
  • World-class athletes often have thresholds within ~6–7% so upper zone 2 becomes highly demanding.
INSIGHT

Training Above Threshold Can Reduce Aerobic Capacity

  • Training above a threshold signals the body to favour anaerobic adaptations and can lower aerobic capacity.
  • Scott: you can nudge thresholds upward from below but cannot drag them upward from above.
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