Analyses of muscular mass and function: the impact on bone mineral density and peak muscle mass

Abstract

Bone density and bone mass are commonly regarded as the essential parameters to describe fracture risk in osteology. Because fractures primarily depend on bone strength and secondarily on bone mass and density, bone strength should be the main parameter to describe fracture risk. The quantitative description of bone strength has the prerequisite that bone geometry is assessed despite bone density. Thus, volumetric osteodensitometric methods should be preferred, which enable the physician to evaluate parameters primarily associated with bone modeling or remodeling. Modeling describes the adaptation of bone geometry to applied muscular forces in contrast to remodeling representing bone turnover. The adaptation of bone geometry to muscle forces led to the term functional muscle-bone unit, which enables the physician to differentiate between primary and secondary bone diseases. Primary bone diseases are characterized by a defective adaptation of bone to muscle forces in contrast to secondary bone diseases, which are primary diseases of the neuromuscular system. Because muscle forces are essential in the feedback loop of bone adaptation to forces (mechanostat), the assessment of muscle function has become an essential part of osteologic diagnostics in pediatrics. Dynamometric and mechanographic methods have been introduced to properly characterize kinetic aspects of muscle function in children and adolescents. Therefore, emphasis should be put on the assessment of muscle function despite the evaluation of osteodensitometric parameters in pediatric osteology.

The Relationship between Physical Activity and Bone during Adolescence Differs according to Sex and Biological Maturity

“…Given the relationship of muscle power to bone mass in boys, it is likely that muscle force accounts for this association [31]. Similar findings were reported by Macdonald and colleagues [28] who found that geometric measures of the tibia (using pQCT) in pre- and early pubertal children (aged 9–11) were significantly and positively correlated with physical activity in boys, but not girls, and with maturity in girls, but not boys.…”

Bone density in patients with late onset Pompe disease

“…In the current study, DXA was used to measure BMD and soft tissue composition in patients with the late onset form of Pompe disease. Although this technique has some limitations, such as the inability to measure cortical area and a real volumetric bone density (17), it remains a common and reliable method to evaluate bone mineral status and is used to diagnose osteoporosis and to predict fracture risk (18). The results reconfirmed that osteopenia may be present at diagnosis time in bones which are adjacent to the insertion of affected muscles, such as femur and lumbar spine.…”

“…The results reconfirmed that osteopenia may be present at diagnosis time in bones which are adjacent to the insertion of affected muscles, such as femur and lumbar spine. Muscle weakness reduces the application of mechanical forces on the skeleton, which are essential for bone remodelling and adaptation to keep high bone strength (17). Similarly, BMD in the proximal femur but not the lumbar spine is severely diminished in boys with Duchenne muscular dystrophy early in the disease course before ambulation is significantly affected (19).…”

Bone and skeletal muscle: Key players in mechanotransduction and potential overlapping mechanisms

“…Furthermore, during post-natal skeletal growth (2–20 yr), there is a very strong positive correlation between muscle mass and bone mass, with gains in muscle mass preceding those in bone mass [22]. In fact, the associations between muscle/strength and bone mass in children are strong enough that clinical techniques for disease diagnosis can be founded upon them [23, 24]. For instance, deficiencies in the amount of bone per unit muscle strength versus deficiencies in both factors allow for classification of diagnoses into primary (true or intrinsic) and secondary (physiologic) bone disorders.…”