Back Pain: Levers of the Spinal Column

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In the most typical and known form, the lever is a rigid bar that rotates around an axis, the Fulcrum, and to which two antagonistic forces are applied:

• The power
• The distance of the Power from the fulcrum is called the Arm of Power.
• The Resistance
• The distance of the Resistance from the Fulcrum is referred to as the Arm of the Resistance.

Leverage is balanced when: Power x Arm of Power = Resistance x Arm of Resistance

the bone segment is the axis of the lever, the joint is the fulcrum, the weight force is the power and the muscle strength is the resistance, therefore the joint lever is in equilibrium when: muscle strength x distance of the muscles from the joint = Weight x distance of weight from the joint.

At the level of the fulcrum of the lever, if we apply it to the lumbar vertebrae, the weight lifted, the force necessary to carry out the task, the weight of the overlying structures (head, thorax, upper limbs and viscera) and the tension generated by the muscles and viscera are added. ligaments acting at this level. This sum is called disc overload.

Why keep a weight closer to the body?

• The shorter the distance of the weight lifted from the joint
• The less muscle strength is needed to lift it, so the less the disc overload will be.

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