Answer: through generation of heat energy during contraction
Generally the large mass of skeletal muscles makes it to contribute to Thermogenesis in mammals. when skeletal muscles contract, they pull on the tendon. Remember muscles are attached to bones by tendons. Therefore the contraction shorten muscles's length , shifting the bone and hence causing movement of the body. This movement generate heat energy. It is a process which involve the expenditure of ATPs, and abundant mitochondria.
The higher the rate of contraction of the muscles , the higher is the heat generated.
It is the lysis of ATPs bonds that liberates heat energy during muscles contraction. Although this process raises the body temperature, it does not favour the body physiological process; because it causes loss of large amount of heat energy from the core body temperature, to the external environment through vasodilated capillaries under the skin. Thus affecting body temperature set points.
in some case the rate of muscle contraction is too high, due to high diffusion of Calcium ions into the muscles this generate too much heat causing Hypothermia, from sustained contraction of skeletal muscles.
