Understanding Levers and Torque in Human Movement

Lever

A simple machine that rotates around an axis.

Fulcrum

Axis of rotation for a lever system.

Motive Torque

Torque caused by motive force causing rotation.

Resistive Torque

Torque caused by resistive force opposing rotation.

Torque Formula

T = f x d, where f is force.

Centric Force

Force applied through the center of mass.

Eccentric Force

Force applied away from the axis of rotation.

Torque Arm

Distance between force line and rotation axis.

Mechanical Advantage (MA)

MA = MAmotive / MAresistive, indicates force efficiency.

1st Class Lever

Axis in the middle; examples include see-saws.

2nd Class Lever

Resistance in the middle; examples include wheelbarrows.

3rd Class Lever

Motive force in the middle; examples include biceps curls.

Range of Motion (ROM)

Distance a joint can move through during activity.

Gait Cycle

Pattern of movement during walking or running.

Stance Phase

Phase where one limb is in contact with ground.

Swing Phase

Phase where limbs are off the ground.

Heel Contact

Initial contact of foot with the ground.

Toe-off

Point where foot leaves the ground.

Pronation

Foot rolls inward during weight-bearing activities.

Supination

Foot rolls outward during weight-bearing activities.

Speed Formula

Speed = distance / time, measures movement rate.

Dorsiflexion

Upward movement of the foot at the ankle.

Muscle Force

Force generated by muscles to produce movement.

Effective Moment Arm

Distance from axis to line of action of force.

Torque Direction

Indicates the rotational effect of forces applied.