Threshold Training: Tradition and Controversy

Introduction

Threshold training (THR), centered on intensity near the second lactate threshold (LT2 / FTP), was regarded as the golden rule for improving endurance performance in the 1990s–2000s. However, after Seiler’s research on polarized training gained traction, the status of threshold training was challenged. This article attempts to objectively review its value and controversies.

Physiological Basis of Threshold Training

When exercise intensity approaches LT2:

• Lactate production equals clearance (highest steady-state point)
• Mitochondrial oxidative capacity is highly activated
• Both slow-twitch fibers and Type IIa intermediate fibers are recruited
• Sustained training can raise LT2 intensity, equivalent to improving FTP

These adaptations are crucial for events such as 40K TTs, criteriums, and hill climbs.

Typical Threshold Workouts

Controversies and Scientific Challenges

Seiler’s core criticism is that threshold training accumulates too much moderate intensity, creating a “gray zone” trap.

• High psychological stress during training (every session approaches the pain ceiling)
• Autonomic nervous system remains sympathetic-dominant long-term, slowing recovery
• Compared with low intensity, VO2max gains are limited
• Compared with high intensity, neuromuscular adaptations are limited

Research Directions

Ingham et al. (2008) found in a study on rowers that the pure threshold training group improved less than the mixed training group. However, Esteve-Lanao et al. (2007) showed in a study on long-distance runners that the threshold group improved significantly, provided it was paired with large amounts of Z1. The debate remains unresolved to this day.

Practical Recommendations

• Do threshold workouts at most 1–2 times per week, never on consecutive days
• The 4–6 weeks before a race are the most valuable phase for threshold training
• Amateur riders may consider Sweet Spot (88–93% FTP) instead of pure threshold work—less stress, similar results
• Monitor HRV; if it drops for 3 consecutive days, reduce volume immediately

Conclusion

Threshold training is not outdated—it simply cannot be used in isolation. Placed within a polarized or pyramidal framework, serving as the “Z2 moderate intensity” role and executed intensively in the 4–6 weeks before a race, it remains an effective means for Taiwanese amateur riders to raise race intensity. The key is not to linger at the edge of FTP all year round.

Related Reading

• Lactate Threshold Training: How to Find Your Cycling Critical Pace
• Cycling Lactate Threshold Training: Sweet Spot 88–93% FTP Interval Design
• Lactate Threshold Intervals: Periodized Application of Sweet Spot Training (88–93% FTP)
• Over-Under Threshold Intervals: The Secret Weapon to Break Through FTP Plateaus