Training-Intensity Distribution (Polarized / Threshold / Pyramidal)

Training-intensity distribution (TID) describes how total training volume is allocated across intensity zones (using a simplified 3-zone scheme: Zone 1 = below LT1/VT1 [easy], Zone 2 = between the thresholds [moderate], Zone 3 = above LT2/VT2 [hard]; see lactate-threshold and heart-rate-zones). Three common models:

• Polarized: a large majority of volume easy (Zone 1, ~75–80%), a small amount very hard (Zone 3, ~15–20%), and minimal time in the moderate middle (Zone 2, <~10%). Often summarized as "80/20" (≈80% easy, ≈20% hard). Meta-analyses report polarized training produces greater improvements in VO2max, peak power, and time to exhaustion than threshold-dominated approaches in many trained athletes.
• Threshold: emphasizes the moderate zone, with substantial volume (>~35%) at/near threshold (Zone 2) and the rest split between easy and hard.
• Pyramidal: volume tapers like a pyramid — most easy (Zone 1), less moderate (Zone 2), least hard (Zone 3) — so it includes meaningful threshold work but still skews easy.

The recurring theme across endurance research is that most volume should be easy, with a deliberately limited dose of high-intensity work — the opposite of the "moderate all the time" pattern many recreational exercisers fall into ("the moderate-intensity trap"). The best model depends on athlete level, sport, and training phase, and programs often shift between models across a periodized season (see periodization-overview). The easy bulk is built from zone-2/LSD work (zone-2-training, long-slow-distance); the hard minority from VO2max intervals (vo2max-intervals); threshold/pyramidal models add tempo work (tempo-threshold-training).

• 3-zone scheme: Z1 below LT1, Z2 between thresholds, Z3 above LT2.
• Polarized ≈ 80% easy / ~minimal moderate / ~20% hard ("80/20").
• Threshold: emphasizes Z2 (>~35% near threshold).
• Pyramidal: tapering — most easy, less moderate, least hard.
• Consensus: keep most volume easy; limit high-intensity dose; avoid the "moderate trap."

• zone-2-training / long-slow-distance — the easy majority.
• vo2max-intervals — the hard minority.
• tempo-threshold-training — the moderate/threshold component.
• lactate-threshold — the thresholds defining the three zones.
• periodization-overview — shifting distribution across a season.