PIRL EXPERIMENTAL · MOVEMENT LAB

Muscles work in pairs

Make a movement. Watch one muscle shorten as its partner lengthens.

CHOOSE A MOVEMENT
Which muscle will pull?

Choose a movement to see the muscles work together.

Contracting / shorter Relaxing / longer
Muscles pull. They do not push bones.

Antagonistic muscles pull in opposite directions. Tendons connect muscles to bones.

Simplified side view; shapes, attachments, and length changes are exaggerated. Other muscles also help. Real muscle pairs can contract together to stabilize a joint.