Relationship Between Physical Activity Level and Muscle Markers in a Population-Based Sample of Children and Adolescents

Objectives: The study aimed was to investigate the relationship between physical activity (PA) levels and muscle markers in healthy children and adolescents. Methods: This cross-sectional study was conducted in 2020 among school students from Isfahan, Iran. Using cluster sampling, 159 students aged 7 to 18 years were selected. In addition to the physical examination, the PA level was assessed using a valid questionnaire. The serum levels of aspartate aminotransferase (AST), lactate dehydrogenase (LDH), creatine kinase (CK), and alanine aminotransferase (ALT) were measured. Statistical analysis was performed using the Pearson correlation test. Results: The samples included 79 girls and 80 boys with a mean age (standard deviation) of 12.72 (3.06) years and a mean body mass index of 18.30 (3.70) kg/m2. The mean AST and CPK were significantly higher in boys than in girls (P < 0.05). Participants with higher PA levels had significantly lower LDH and ALT than other participants (-0.20, P = 0.003, and 0.044 P = 0.295, respectively). There was no significant relationship between PA level and muscle enzyme levels. Conclusions: The findings of this study indicated that higher PA level was associated with lower serum muscle markers other than LDH. This suggests that the best types of PA for children and adolescents are those activities with rest sets to prevent muscle damage.