Associations of sport participation, muscle-strengthening exercise and active commuting with self-reported physical fitness in school-aged children.

Background: Numerous studies suggest a positive association between physical activity and physical fitness in schoolchildren. However, little is known about some neglected forms of physical activity and their associations with physical fitness. This study was conducted Purpose: This study explores the associations between participating in sports, muscle-strengthening exercises, and active commuting with self-reported physical fitness assessed by the International Fitness Scale (IFIS). Methods: A total of 3,807 study participants (ages 11-17) from 12 public schools in South-eastern China were recruited, with 2,407 providing valid data on variables for analysis. Study participants were asked to self-report their sociodemographic factors (i.e., sex, grade, age), participation in sports (never, 1-3 times per month, 1-2 times per week, and 3 or more times per week), muscle-strengthening exercise (0-7 days) and active commuting (0-5 days). Generalized linear models were used to explore the associations between sports participation, muscle-strengthening exercise, and active commuting with self-reported physical fitness (comprising general physical fitness, cardiorespiratory fitness, muscular strength, speed and agility, and flexibility). A total of 2,407 children and adolescents with a mean age of 13.82 (±2.1) years were included in the study's final analysis. Results: The study found no significant association between active commuting and physical fitness. Regarding participating in sports and muscle-strengthening exercises, positive, significant associations were found, which showed that a higher frequency of participating in sports and more participation in muscle-strengthening exercises are associated with improved physical fitness. Conclusion: This study offered evidence on the roles of some aspects of physical activity in physical fitness. To promote health in children and adolescents, they should be encouraged to participate in more sports and engage in muscle-strengthening exercises.