Lean mass as a total mediator of the influence of muscular fitness on bone health in schoolchildren: a mediation analysis.
This report aims to analyse the independent association of lean mass and muscle fitness with bone mineral content (BMC) and bone mineral density (BMD), and to examine whether the relationship between muscle fitness and bone health is mediated by lean mass. Body composition (by dual energy X-ray absorptiometry (DXA)), muscle fitness, physical activity, age and height were measured in 132 schoolchildren (62 boys, aged 8-11 years). Analysis of covariance tested differences in bone-related variables by lean mass and muscle fitness, controlling for different sets of confounders. Linear regression models fitted for mediation analyses examined whether the association between muscle fitness and bone mass was mediated by lean mass. Children with good performance in handgrip and standing long jump had better and worse bone health, respectively. These differences disappeared after controlling for lean mass. Children with high lean mass had higher values in all bone-related variables. In addition, the relationship between muscle fitness and bone mass was fully mediated by lean mass. In conclusion, the relationship between upper-limbs muscle fitness and bone health seems to be dependent on lean mass but not on muscle fitness. Schoolchildren with high lean mass have more BMC and BMD in all regions. Lean mass mediates the association between muscle fitness and bone mass.
a School of Nursing and Physiotherapy , University of Castilla La Mancha , Toledo , Spain.
Ana
A
Torres-Costoso
Luis
L
Gracia-Marco
Mairena
M
Sánchez-López
Jorge Cañete
JC
García-Prieto
Antonio
A
García-Hermoso
Ana
A
Díez-Fernández
Vicente
V
Martínez-Vizcaíno
D015502:Absorptiometry, Photon; D001823:Body Composition; D015992:Body Mass Index; D015519:Bone Density; D002648:Child; D003430:Cross-Sectional Studies; D005080:Exercise Test / Q000379:methods; D006801:Humans; D035002:Lower Extremity / Q000502:physiology; D008297:Male; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D034941:Upper Extremity / Q000502:physiology
body composition; bone mineral content; bone mineral density; children; muscular strength