Skeletal muscles move body segments with respect to each other against internal and external resistances. Shortening is the only active function of the muscle. Nervous signals stimulate muscle components either to shorten dynamically, to statically retain their length or to allow being lengthened. Various methods and techniques are available for assessing muscular control and strength. The engineering application of data on available body strength requires the determination of whether minimal or maximal exertions, and static or dynamic, are the critical design considerations. The major point that this thesis deals with is the study of electromechanical behavior of skeletal muscle in response to applying load and electrical stimulation. All of the experiments were carried on frog and human, so that thirty six specimens were dissected from frog lower limb,divided equally into eighteen for right and left gastrocnemius muscles which always hydrated to prevent the tissue dryness. Then the electrical behavior was studied on 19 volunteers using right and left legs so38 specimens were used. There were two types of experiments; (1) study the mechanical behavior and (2) study electrical behavior. The force-length curve found from the first experiment explains relationship between muscle tension and displacement in active and passive state and from the second part shows the relationship between the degrees of contraction of leg and number of motor units that activated that measured from the electrical signal of the lower limb by EMG machine. The result show that active tension increase then it remained constant then it descend while passive tension continue to increase due to the exist of titin protein inside the muscle and the amplitude of electrical signal increase then descend after that it increase again while duration increase continuously all of that due to increase in number of motor unit after each contraction.