Intensity Distribution in Running Training: Polarized vs Threshold Training for PB Benefits

Introduction

In the world of running training theory, there is a debate that has raged on for 20 years without pause: Polarized Training or Threshold Training—which is better?

The former advocates “80% easy + 20% very high intensity,” barely touching the moderate intensity zone; the latter emphasizes “heavy lactate threshold training,” spending significant time in the moderate-to-high intensity range. Both theories have their loyal followers and scientific research to back them up.

For amateur road runners in Taiwan, understanding the differences between the two can help you design your training plans more intelligently and break through PB plateaus.

Definitions of the Two Training Models

• Low intensity: Easy runs, heart rate < 75% of max heart rate
• Moderate intensity: Near lactate threshold, heart rate approximately 82–92% of max heart rate
• High intensity: VO2max intervals and above, heart rate > 93% of max heart rate

The Scientific Basis of Polarized Training

The theoretical foundation of polarized training comes from exercise physiologist Stephen Seiler’s research on Nordic elite endurance athletes. He found that the actual intensity distribution of the world’s top skiers, rowers, cyclists, and long-distance runners is almost universally the “80/5/15” polarized pattern.

Why so little moderate intensity?

• Moderate-intensity training (near lactate threshold) places nearly the same recovery demands on the body as high-intensity training, yet its physiological stimulus is less significant than that of high-intensity training
• Moderate-intensity training easily traps runners in a “gray zone”—too fast to recover from, yet too slow to provide adequate stimulus
• The polarized model allows high-intensity sessions to be completed at higher quality (because easy runs provide sufficient recovery)

Taiwanese research support: A 2021 study on amateur marathon runners showed that the group following polarized training for 16 weeks improved their 5km times by an average of 1.8% more than the threshold training group.

The Scientific Basis of Threshold Training

Proponents of threshold training, such as Dr. Jack Daniels (author of Daniels’ Running Formula), argue that extensive training at lactate threshold pace is the core of improving marathon performance.

Advantages of lactate threshold training:

• Directly improves sustainable “cruising speed” (maximal lactate steady state, MLSS)
• Particularly effective for marathon and half-marathon distances, as these distances rely primarily on aerobic output near the lactate threshold
• Training plans are easier to structure, and runners experience a stronger psychological sense of “completion”
• Suitable for runners with insufficient weekly mileage (below 50km), as high-intensity intervals carry a higher injury risk when base mileage is low

Which Training Suits Taiwanese Amateur Runners Better?

The answer is not an either/or proposition, but rather depends on your circumstances:

Runners recommended to adopt “polarized training as the primary approach”:

• Weekly mileage of 60km or more
• More than 2 years of consistent running experience
• PB plateau lasting more than 6 months
• Ability to schedule at least 2 high-quality interval sessions per week

Runners recommended to adopt “threshold training as the primary approach”:

• Weekly mileage of 30–50km
• 1–2 years of training experience
• Currently transitioning from a completion-oriented to a performance-oriented mindset
• Lacking an interval training foundation

The most pragmatic compromise: Adopt a “modified polarized” approach—75% easy runs + 15% high-intensity intervals + 10% lactate threshold runs—taking the best of both worlds.

Practical Recommendations

• The solution to a plateau: If your performance hasn’t budged after 6+ months of threshold training, try switching to a polarized model for 8–12 weeks—this can often break through the plateau
• Taiwan’s environmental constraints: Taiwan’s summer heat and humidity make it easy for heart rate to run high during easy runs. When using polarized training, consider using “heart rate control” instead of pace control to ensure low-intensity runs are truly low intensity
• Track your intensity distribution: Use the heart rate zone analysis features in tools like Garmin or Strava to review monthly whether your intensity distribution matches your expectations

Conclusion

Polarized training and threshold training are both effective methods backed by scientific evidence. For Taiwanese amateur runners, the most important thing is not to blindly follow any single theory, but to understand your current training status and choose the intensity combination that delivers the most physiological stimulus. Breaking through a PB often comes from one smart adjustment to your training structure.

Related Reading

• Triathlon Intensity Allocation: Applications of Polarized vs. Threshold Training in Triathlon
• The 80/20 Training Principle in Running: The Scientific Basis for 80% Low Intensity, 20% High Intensity
• Polarized vs. Pyramidal Training: Physiological Evidence and Applicable Scenarios for Two Intensity Distributions
• The Complete Guide to Polarized Training: Why Do Pro Cyclists Spend 80% of Their Time “Riding Slow”?