Lower body muscular strength as a predictor of health indicators in youth population: A systematic review and meta-analysis

Muscular strength in the lower body during childhood and adolescence is crucial for determining various health indicators. While previous reviews have examined the benefits of health-related muscular fitness (MF) in youth, this study aims to analyse a specific indicator of muscular fitness, focusing on current evidence regarding lower-limb muscular strength and power tests as predictors of health parameters in children and adolescents. A systematic search was conducted in Web of Science, MEDLINE (PubMed), and Scopus databases up to December 2023. Observational studies were considered if they quantitatively assessed the association between lower body muscular strength and health outcome variables. Meta-analyses were performed to determine the pooled standardized coefficients. Age was evaluated as a potential moderating factor. Twenty-four studies (n = 121306) were included, covering outcomes like adiposity, cardiometabolic risk, bone health, and inflammatory biomarkers. Meta-analyses of 11 studies revealed pooled standardized coefficients; statistical significance was determined for p < 0.001. Lower body strength/power was negatively associated with multiple adiposity indicators: waist circumference (r = −0.27), body fat percentage (r = −0.31), sum of skinfolds (r = −0.31). Additionally, significant negative correlations were observed with insulin resistance (r = −0.20), and cardiometabolic risk index (r = −0.27). Associations with systolic (r = 0.14) and diastolic (r = 0.07) blood pressure, and bone mineral density of the femoral neck (r = 0.12) were weaker. Lower body muscular strength predicts health outcomes like obesity and cardiometabolic diseases. Although no direct link to bone mass was found, lean mass influenced by muscle is essential for bone health. Further research is needed to clarify these relationships and guide interventions, supporting guidelines promoting muscle-strengthening activities in youth.