Size Principle
Motor units are recruited from smallest to largest as force demands increase.
Updated
The size principle (Henneman's size principle) states that motor units are recruited in order from smallest to largest based on force requirements. Low-force activities use only small motor units; high-force activities recruit progressively larger units. This is why heavy training is needed to fully recruit and train all motor units, including high-threshold ones.
Examples
- Walking uses small motor units
- Maximal lifts recruit all motor units
- Why heavy training builds strength
Related Terms
Compound exercises
Put this into practice with exercises from the library.
Single-Arm Push-Up
Strength · Bodyweight
Single-Leg High Box Squat
Strength · Other
Single-Leg Hop Progression
Plyometrics · Other
Single-Leg Lateral Hop
Plyometrics · Other
Single-Leg Stride Jump
Plyometrics · Other
Single Leg Butt Kick
Plyometrics · Bodyweight
Single Leg Push-off
Plyometrics · Other
Sled Drag - Harness
Strongman · Other
Common questions
What is Size Principle?
Motor units are recruited from smallest to largest as force demands increase. The size principle (Henneman's size principle) states that motor units are recruited in order from smallest to largest based on force requirements.
What exercises train the Size Principle?
Good options include Single-Arm Push-Up, Single-Leg High Box Squat, Single-Leg Hop Progression, Single-Leg Lateral Hop, Single-Leg Stride Jump. Each links to a step-by-step guide with demonstration images.
What are examples of Size Principle?
Walking uses small motor units; Maximal lifts recruit all motor units; Why heavy training builds strength.
Put it into practice
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A 12-week, four-day hypertrophy plan in three phases, with a modest calorie surplus