Answer: Circulatory and respiratory system
During a process of workout, the rate of breathing increases, because of increase in demand of oxygen by the body. Work out affects the function of the lungs which is a part of the respiratory system. The heart tries to pump out blood fastly, to transfer oxygenated blood all over the body. The heat energy is liberated in this process, which results in the release of sweat by the skin. The sweat gets evaporated by the external air, which keeps the body cool.