The health benefits of muscular fitness for children and adolescents: a systematic review and meta-analysis.
BACKGROUND
Physical fitness during childhood and adolescence has been identified as an important determinant of current and future health status. While research has traditionally focused on the association between cardio-respiratory fitness and health outcomes, the association between muscular fitness (MF) and health status has recently received increased attention.


OBJECTIVE
The aim of this systematic review and meta-analysis was to evaluate the potential physiological and psychological benefits associated with MF among children and adolescents.


METHODS
A systematic search of six electronic databases (PubMed, SPORTDiscus, Scopus, EMBASE, PsycINFO and OVID MEDLINE) was performed on the 20th May, 2013. Cross-sectional, longitudinal and experimental studies that quantitatively examined the association between MF and potential health benefits among children and adolescents were included. The search yielded 110 eligible studies, encompassing six health outcomes (i.e., adiposity, bone health, cardiovascular disease [CVD] and metabolic risk factors, musculoskeletal pain, psychological health and cognitive ability). The percentage of studies reporting statistically significant associations between MF and the outcome of interest was used to determine the strength of the evidence for an association and additional coding was conducted to account for risk of bias. Meta-analyses were also performed to determine the pooled effect size if there were at least three studies providing standardised coefficients.


RESULTS
Strong evidence was found for an inverse association between MF and total and central adiposity, and CVD and metabolic risk factors. The pooled effect size for the relationship between MF and adiposity was r = -0.25 (95% CI -0.41 to -0.08). Strong evidence was also found for a positive association between MF and bone health and self-esteem. The pooled effect size for the relationship between MF and perceived sports competence was r = 0.39 (95% CI 0.34-0.45). The evidence for an association between MF and musculoskeletal pain and cognitive ability was inconsistent/uncertain. Where evidence of an association was found, the associations were generally low to moderate.


CONCLUSIONS
The findings of this review highlight the importance of developing MF in youth for a number of health-related benefits.
Priority Research Centre for Physical Activity and Nutrition, School of Education, University of Newcastle, Callaghan Campus, Newcastle, NSW, Australia, jordan.smith@uon.edu.au.
Jordan J
JJ
Smith
Narelle
N
Eather
Philip J
PJ
Morgan
Ronald C
RC
Plotnikoff
Avery D
AD
Faigenbaum
David R
DR
Lubans
D050154:Adiposity; D000293:Adolescent; D015519:Bone Density; D002318:Cardiovascular Diseases / Q000517:prevention & control; D002648:Child; D003071:Cognition / Q000502:physiology; D006304:Health Status; D006801:Humans; D018482:Muscle, Skeletal / Q000502:physiology*; D059352:Musculoskeletal Pain / Q000517:prevention & control; D010809:Physical Fitness / Q000502:physiology* / Q000523:psychology*; D012307:Risk Factors; D012649:Self Concept