The different parts of your musculoskeletal system operate under the control of the nervous system to produce voluntary movement. impulses fromthe nervous system cause muscles to contract, when it contracts it shortens.
Increased blood supply
Before the start of exercise your heart rate usually increases above resting levels. This is known as anticipatory heart-rate response. This is because the nerves that directly supply the heart and chemicals in the blood can rapidly alter the heart rate. Vessels can also shut down blood flow to tissues, which can temporarily lessen their blood supply. This involves a decrease in the diameter of the blood vessel, resulting in reduced blood flow to the muscles. At the start of exercise, or even slightly before, nerve centres in your brain detect cardiovascular activity. This results in adjustments that increase the rate and pumping strength of your heart.
Increase in muscle pliability
As you exercise your muscles become warmer becuase mor blood is being pumped to them, this means they become more pliable and allows you to be more flexible.
Increased range of movement
the acute responses to execise on your skeletal system are demonstarted by changes in the joint, the movement oif joints is stimulates from synovial fluids, as you start to exercise the fluid becomes more of a lubricant and allows more movement around the joint.