Muscle fitness is the cornerstone of all sports activities practitioners, and for specialization in the sports field Muscular Fitness is a term that includes the strengths of various forms, and it achieves the individual's self, giving him a good form of strength, as it depends on the performance of most sports activities and its availability is a necessity to reach the individual to Championships in many sports The research aims to identify the predictive ratios of some of the determinants contributing to the components of muscle fitness (maximum strength - strength characterized by velocity - bearing strength) for athletes from 15-18 years. The researcher used the descriptive method and the research sample was chosen in the deliberate way from the students of the sports secondary school for the gifted and those between the ages of (15-18) years for the academic year 2009/2010 AD and practices for activities in Sharkia governorate. The research sample represents the students of the three classes and their number (117) players The most important results were the prediction of the maximum muscle strength as a component of the muscle fitness in terms of the variables of the total length of the body, weight, muscle mass, body mass index by up to 72.61%, and the prediction of the strength marked by speed (muscular capacity) as one of the components of muscle fitness in terms of the elasticities of the hip joint, mass Muscle, body mass index, knee joint flexibility, foot joint flexibility, lower limb length (legs), arms length by up to 61.15%., Prediction of strength tolerance as a component of muscle fitness in terms of kinetic velocity variations, thigh joint elasticity, body mass index , Mass Fat by up to 49.76%