I am going to school for physical therapy, I am not sure what you are learning in you class but the most common we use that deals with math is angles of pull and torque. All the muscles in your body work at different angles to get the job done. Some muscles use bones (like the knee cap) to increase the angles, therefore increasing the efficiency of the muscle. Some muscles are made to help with more movement. Like you biceps while others are made to be more powerful like you deltoids. Let me know if this helps you. Remember to be a good PT you need to understand the way the muscles and everything else in the body works, so you can help it get better! Good luck!