Muscle physiology is the study of how muscles function and produce movement in the body. Muscles are made up of cells called muscle fibers, which contract and relax to create force. This process is controlled by signals from the nervous system, allowing us to perform various activities, from walking to lifting heavy objects. There are three main types of muscles: skeletal, smooth, and cardiac. Skeletal muscles are attached to bones and help with voluntary movements, while smooth muscles control involuntary actions like digestion. Cardiac muscle makes up the heart and is responsible for pumping blood throughout the body. Understanding muscle physiology helps us improve fitness and treat injuries.