Until about two and half centuries ago, muscle-power had been the prime source of energy for performing all the physical activities on our earth, and much of the muscle-power was from human muscles. Because of the socio-economical conditions of the farmers in several developing countries including India, the human muscle power will go on contributing the energy requirements for performing many farmactivities at least for next two-three decades. In remote villages in India where electric power is not available and repair and maintenance facilities for internal combustion engines are in scarce human and animal power are still the major contributors of energy requirement for production agriculture as well as for post harvest agricultural operations. Poor tribal populations in many tribal districts have nothing to spend for energy requirements for farm operations but the muscle power may it be the animal or human muscles. Muscle power may be considered as one of the environment friendly renewable sources of energy, and human muscle power if utilized properly and judiciously may keep him free from many cardiovascular (blood pressure, sinus-arrhythmia), respiratory (asthma), musculoskeletal (arthritis, rheumatism etc.) and urino-genital (diabetes) diseases. The usable external power output of the body varies with the duration of activity and is limited by different factors. In single movement of less than a second a healthy champion athlete may produce power up to 4.5 kW, which may-be limited by intrinsic power production of the muscle, and by the difficulty of coupling a large mass of muscle to a suitably matched load. In brief bouts of exercise of 0.1 to 5 minutes duration the power production may range from 0.4 to 1.5 kW, which is limited by the availability of stores of chemical substances in the muscles that can yield energy by hydrolysis. The power production in steady state work of 5 to 130 min or more duration may range from 0.3 to 0.4 kW and is limited by the cap
