Newton's Laws Session 2 POST - Part 3 PDF

Movement Science 1: Session II Newton’s Laws Adapted with permission from Dr. Cole, George Washington University Program in Physical Therapy, 2023 Free Body Diagram - Clinical Case: Cane  Clinical Case: Cane Your patient...

Movement Science 1: Session II Newton’s Laws Adapted with permission from Dr. Cole, George Washington University Program in Physical Therapy, 2023 Free Body Diagram - Clinical Case: Cane  Clinical Case: Cane Your patient is using a cane to decrease the force required in the gluteus muscles. Do you have them use the cane in the ipsilateral or contralateral hand?  Clinical Case: Cane First solve for holding cane in contralateral hand 1) Identify and isolate the free body under consideration  Clinical Case: Cane First solve for holding cane in contralateral hand 2) Establish a coordinate reference frame y x  Clinical Case: Cane First solve for holding cane in contralateral hand 3) Draw the internal and external forces that act on the system y x 𝐹𝑀 𝐹𝑊 𝐹𝐶 𝐷𝑊 𝐷𝑀 𝐷𝐶  Clinical Case: Cane First solve for holding cane in contralateral hand 4) Draw the joint reaction force y x 𝐹𝑀 𝐹𝑊 𝐹𝐽 𝐹𝐶 𝐷𝑊 𝐷𝑀 𝐷𝐶  Clinical Case: Cane First solve for holding cane in contralateral hand 5) Write the governing equations of motion Torque from is zero because by definition it goes through the axis of y rotation x Σ = 0 and = Fd 𝐹𝑀 𝐹𝑊 0 = () + () - () 𝐹𝐽 𝐹𝐶 = 𝐷𝑊 𝐷𝑀 𝐷𝐶  Clinical Case: Cane Then solve for holding cane in ipsilateral hand: Torque from is zero because by definition it goes through the axis of y rotation x Ipsilateral: 𝐹𝑀 𝐹𝑊 Σ = 0 and = Fd 𝐹𝐽 0 = () - () - () 𝐹𝐶 = 𝐷𝑊 Contralateral was: 𝐷𝑀 = So putting the cane in the contralateral hand, 𝐷𝐶 minimizes the muscle force! Makes sense because the cane creates torque in the same direction the muscle does Free Body Diagram - Clinical Case: Bag  Clinical Case: Bag Your patient needs to carry a heavy bag and wants to limit the joint reaction force in their hip to decrease pain. Do they carry the bag in the ipsilateral or contralateral side? CONTRALTERAL: Answers  Clinical Case: Bag Your patient needs to carry a heavy bag and wants Torque from is zero because by to limit the joint reaction force in their hip to definition it goes through the axis of decrease pain. Do they carry the bag in the ipsilateral or contralateral side? rotation CONTRALTERAL: y Σ = 0 and = Fd 0 = () - () - () x = 𝐹𝑀 𝐹𝑊 𝐹𝐽 𝐹𝐵 We know Σ = 0 0=- - - =+ + 𝐷𝑊 =+ + 𝐷𝑀 𝐷𝐵  Clinical Case: Bag Your patient needs to carry a heavy bag and wants Torque from is zero because by definition it goes to limit the joint reaction force in their hip to through the axis of rotation decrease pain. Do they carry the bag in the Σ = 0 and = Fd ipsilateral or contralateral side? 0 = () + () - () Ipsilateral: = y Ipsilateral We know Σ = 0 x 𝐹𝑀 0=- - - 𝐹𝑊 =++ 𝐹𝐵 𝐹𝐽 Contralateral was: =+ + 𝐷𝑊 So joint reaction force is less, when they carry the bag 𝐷𝑀 in the ipsilateral hand. This makes sense since it creates torque in the same direction as the muscle 𝐷𝐵