Polarized training

Polarized training is an endurance intensity split in which most work is easy and the rest is hard.^{1Viada, The Ultimate Hybrid Athlete, p. 132.} It grew from observations that elite endurance athletes did 80% to 88% of their training below the ventilatory threshold or aerobic threshold and the remainder at or above threshold.^{1Viada, The Ultimate Hybrid Athlete, p. 132.}

The familiar “80/20 training” label leaves room for interpretation: Viada notes disagreement over whether the hard 20% counts sessions, their total duration or time spent at intensity within sessions, and whether coaches use heart rate or prescribed intensity.^{1Viada, The Ultimate Hybrid Athlete, p. 132.} Successful programs have used each reading.^{1Viada, The Ultimate Hybrid Athlete, p. 132.} Coaches also debate 80/20 versus pyramidal distributions such as 70/20/10; Viada argues that any can work when coaches know the athlete and the definitions they’re using.^{1Viada, The Ultimate Hybrid Athlete, p. 132.}

In practice

Most runners spend most of their running time at an easy, conversational pace.^{2Daniels, Daniels’ Running Formula, 4th ed., p. 85.} Daniels advises against replacing an easy day with another hard session because easy days allow recovery from quality sessions.^{3Daniels, Daniels’ Running Formula, 4th ed., p. 86.}

High training frequency also calls for easy work: advanced triathletes doing 9 to 18 workouts a week have to make most of them easy.^{4USA Triathlon, Complete Triathlon Guide, p. 89.} For hard running, Daniels limits threshold-pace work in a single session to 10% of weekly mileage.^{5Daniels, Daniels’ Running Formula, 4th ed., p. 92.}