This enhances both speed and strength and reduces the likelihood of muscles being overstretched and injured. Blood temperature increases. As it travels through the muscle, the temperature of the blood increases. As blood warms, the amount of oxygen it can hold is reduced. The blood gives up the oxygen to the muscles, so a slightly greater volume of oxygen is made available to the working muscles, enhancing endurance and performance.
Range of motion improves.
The range of motion around joints increases, especially if flexibility exercises are part of the warm-up. Hormone production increases. More of the hormones responsible for regulating energy production are produced. They, in turn, begin making more carbohydrates and fatty acids available for energy production. Metabolism, the body's ability to process energy, improves.