Objectives: The physical component of tasks can be a problem because of muscle weakness; therefore, this research was performed to investigate the relationships between some physical fitness factors and muscle damage enzyme levels in people with mild Intellectual Disabilities (ID). Methods: In this cross-sectional study, 314 students with ID (Body Mass Index [BMI]: 23.42±4.84 kg/m2), after measuring their anthropometric variables (height, weight, and BMI), performed the Canadian Standardized Test of Fitness (CSTF). This test includes flexibility (sit and reach test), muscle endurance (Push-ups and Sit-ups tests), muscle strength (Hand-grip test), and cardiorespiratory endurance (Canada Home Fitness test). Then saliva samples were collected from 20 subjects who were homogeneous for age (Mean±SD: 20.30±2.27 years), sex (male only), and type of ID, for measuring their saliva levels of Creatine Phosphate Kinase (CPK), Lactate Dehydrogenase (LDH), and C-reactive Protein (CRP). Data were analyzed by the Pearson correlation coefficient and linear and nonlinear regressions (P<0.05).  Results: The findings indicated significant relationships between some of the physical fitness factors and some enzymes of muscle damage (P<0.05). The results indicated significant relationships between CPK, with push-ups, sit-ups, and hand-grip strength, as well as between the LDH with push-ups and CRP with sit-ups and hand-grip strength (P<0.05). Discussion: According to the results of the present research, CPK, LDH, and CRP saliva levels in males with an ID have a significant relationship with some of the physical fitness components. Also, the results of the present research have provided equations for estimating CPK, LDH, and CRP saliva levels through CSTF battery test scores in people who have an educable ID.