A Ph.D. thesis was discussed in the College of Physical Education and Sports Sciences, University of Tikrit on the effect of special exercises in developing some aspects of muscle strength and muscle balance of the lower extremities of soccer players by the postgraduate student, Mr. Qusay Ali Mahmoud. The thesis aimed at developing some types of strength and muscle balance to prevent posterior thigh muscle strain in young soccer players under 19 years old. The thesis demonstrated building test units to measure the strength and velocity of the anterior and posterior muscles of the man among young soccer players under the age of 19, as well as building test units to measure the dynamic balance of the right-left man among young soccer players under the age of 19. The thesis concluded that the preventive exercises developed by the researcher contributed to the development of the study variables among the members of the research sample and also showed significant differences between the results of the pre and post tests for the experimental group and in favor of the posttest in all the study variables.