Definition
Practising a movement many times a day at an easy effort, far from failure, to improve strength and skill through frequency.
Pavel Tsatsouline's method: pick one lift (a pull-up, a pistol squat, a press), do 40 to 60% of your max reps, five to ten times spread through the day, most days, never near failure. A client with a max of 8 pull-ups does sets of 3 or 4 all day.
It treats strength as a skill, and frequent low-fatigue practice builds skill. It works for bodyweight movements and stuck lifts; it does not work for heavy barbell training or for size.
Run it for three to four weeks, then retest.