Issue link: https://www.massageandbodyworkdigital.com/i/992435
A B M P m e m b e r s e a r n F R E E C E a t w w w. a b m p . c o m / c e b y r e a d i n g M a s s a g e & B o d y w o r k m a g a z i n e 45 Third-class levers are the most common type of lever in the human body and are demonstrated by flexing the elbow to raise the hand toward the shoulder. The elbow joint is the axis, while the biceps brachii and brachialis muscles just distal provide the force. Resistance is the weight of the forearm and whatever is held in the hand. APPLICATION TO BODYWORK Identifying which type of lever is used in a given region clarifies function and assists in making appropriate treatment goals for optimal performance, injury prevention, and treatment. Supporting balanced muscle length and strength in the vertebral column makes sense, as does recognizing the tendency of the ankle plantar flexors to shorten with use in explosive activities, since second-class levers emphasize force over range of motion. Most of the mobile joints in the body require full range of motion to function optimally, as this is characteristic of third-class levers. Christy Cael is a licensed massage therapist and certified strength and conditioning specialist. Her private practice focuses on injury treatment, biomechanical analysis, craniosacral therapy, and massage for clients with neurological issues. She is the author of Functional Anatomy: Musculoskeletal Anatomy, Kinesiology, and Palpation for Manual Therapists (Lippincott Williams & Wilkins, 2009). Contact her at christy_cael@hotmail.com. Identifying which type of lever is used in a given region clarifies function and assists in making appropriate treatment goals for optimal performance, injury prevention, and treatment. A second-class lever in the body is found in the ankle, where power and propulsion are critical. Here, the axis is the ball of the foot, and strong calf muscles (plantar flexors) attaching to the heel provide the force. The resistance comes from the weight of the body compressing down through the tibia between the two. This powerful lever propels the body when walking, running, and jumping. It also helps explain why the calf muscles are so large compared to the smaller shin muscles (dorsiflexors). Third-Class Levers Third-class levers are those with the resistance on one end, the axis on the other, and the force between the two. A shovel is a third-class lever (see Image 3). The ground provides resistance when you dig the end in. Force is provided when you lift the middle of the handle. Your other hand provides the axis at the far end of the handle. These levers emphasize speed and range of motion. Second-class lever Third-class lever 2 3