A single nerve zap gives a quick twitch. Fire them faster and the twitches pile up into a smooth, powerful, sustained pull. Pick a stimulation pattern and watch the tension.
Single twitch
Muscle tensionstimulate faster โ more force
๐ก The body also gets more force by recruitment โ activating more (and bigger) motor units. A motor unit = one motor neuron + every muscle fiber it controls.
๐ท Reference image
A real labeled figure to compare with the interactive above.
Motor Units & Tension โ OpenStax, CC BY 4.0 (via Wikimedia Commons)