Feb 4 notes

moment arm (or lever arm) is abbreviated with:

• MA
• D
• l

Hamstring Curl Example

Letting $m$ be the mass, the length of the shank be $s$, and the knee flexion angle be $\theta$, the torque from the weight is $$\tau = 9.81(m)\cdot s(\cos\theta).$$

Note: the orange dashed line is the moment arm of the hamstrings, and not the angle. As an exercise, show that the same answer can be obtained by calculating the component of $F_H$ which is perpendicular to the tibia, then using the the moment arm from joint to insertion.

ACL Rehab Example

OA example