When you exercise, your body’s ability to sense environmental conditions like temperature, hydration levels, and physical fatigue allows you to adjust your activity level. For instance, if it's too hot outside, your body will sweat more to cool you down, and you may feel a decrease in energy, making you to hydrate and adjust your pace. During exercise, your circulatory system increases blood flow to your muscles, ensuring they get the nutrients and oxygen they need for energy. This is why your heart rate increases when you exercise. it's delivering more oxygenated blood to fuel your muscles for activity.When you're running, for instance, the muscles in your legs contract, pulling on the bones in your lower body. The nervous system sends signals to coordinate and control these movements, making it possible for you to increase or decrease speed, change direction, or perform more complex movements like jumping or squatting. When you're physically active, your body increases immune function to protect against infection and injury. For example, after a strenuous workout, your muscles may experience micro-tears, but your immune system helps repair and strengthen them. Additionally, if you're sweating during a workout, your skin helps protect against harmful bacteria, while your body uses the inflammatory response to heal any minor injuries.
