The Association of Screen Time with Isometric Back and Leg Muscle Strength in School-aged Children

Objective: Long recreational screen time affects many aspects of children's health. We aimed to assess the association of screen time with isometric back and leg muscle strength in school-aged children. Method: Healthy children aged between 7-11 years were enrolled in this study. Gender of the children, their weight, and height at enrollment were recorded. A research assistant surveyed the parents of each child with face-to-face interview technique in order to analyse child's screen-viewing behavior. Children participating in the study were divided into 2 groups according to their average daily screen time (group 1: ≤ 2 hours, group 2: >2 hours). The children in Groups 1 and 2 were also divided into subgroups according to their body mass index (BMI) percentiles. The back and leg muscle strength were measured by using isometric back-leg strength dynamometer. The demographic characteristics, BMI Z-scores and the back and leg muscle strength of the children in groups were compared statistically. Results: A total of 307 children including 103 boys (33.6%) and 204 girls (66.4%) were enrolled in the study. There were 204 (66.4%) and 103 (33.6%) children in groups 1 and 2, respectively. There was no statistically significant difference between the two groups in terms of back and leg muscle strength. The BMI Z-score of children positively correlated with their back and leg muscle strength, respectively. Conclusion: This study could not find an association between screen time and both back and leg muscle strength of children. There is a need for further studies to analyse the effects of other confounding factors such as physical activity, sedentary behaviors, sleep duration and quality, sociodemographic factors and seasonal influence in associaton with screen time in muscle strength outcome measures in children.