Hind limb muscles influence the architectural properties of long bones in frogs.

The Mechanostat Theory states that osteocytes sense both the intensity and directionality of the strains induced by mechanical usage and modulate the bone design accordingly. In long bones, this process may adapt anterior-posterior and lateral-medial strength to their mechanical environment showing regional specificity. Anuran species are ideal for analyzing the muscle-bone relationships related to the different mechanical stresses induced by their many locomotor modes and habitat uses.

Relationship between physical activity, lean body mass, and bone mass in the Mexican adult population.

Unlabelled: We evaluated the association between leisure-time physical activity (LTPA), bone mineral content (BMC), and lean mass (LM) in whole body (wb) and limbs of the Mexican adult population. Our results demonstrate that some types of LTPA with relatively high/medium impact on bones such as football, basketball, tennis, and weightlifting improve BMC and LM.

Purpose: To evaluate the effect of different kinds of leisure-time physical activity (LTPA) on bone mass values and its association with lean mass (LM) in the whole body (wb) and limbs of a large sample of Mexican men and premenopausal (pre-MP) women.

S1 Guidelines on Bone Impairment in Spinal Cord Injury.

During the acute and chronic phase of spinal cord injury (SCI) bone turnover and structure are affected. Bone mineral density of lower limbs is decreased up to 28%-50% below that of age-matched peers at 12-18 mo post injury. Coexisting secondary etiologies of osteoporosis may be present, and during ageing additional loss of bone occurs.

Greater maintenance of bone mineral content in male than female athletes and in sprinting and jumping than endurance athletes: a longitudinal study of bone strength in elite masters athletes.

Unlabelled: We investigated longitudinal changes in tibia bone strength in master power (jumping and sprinting) and endurance (distance) athletes of both sexes. Bone mass but not cross-sectional moment of inertia was better maintained in power than endurance athletes over time, particularly in men and independent of changes in performance.

Objective: Assessment of effects of sex and athletic discipline (lower limb power events, e.

Biomechanical properties of anuran long bones: correlations with locomotor modes and habitat use.

Long bones are subjected to mechanical loads during locomotion that will influence their biomechanical properties through a feedback mechanism (the bone mechanostat). This mechanism adapts the spatial distribution of the mineralized tissue to resist compression, bending and torsion. Among vertebrates, anurans represent an excellent group to study long bone properties because they vary widely in locomotor modes and habitat use, which enforce different skeletal loadings.

Differences in the Cortical Structure of the Whole Fibula and Tibia Between Long-Distance Runners and Untrained Controls. Toward a Wider Conception of the Biomechanical Regulation of Cortical Bone Structure.

The cortical structure of human fibula varies widely throughout the bone suggesting a more selective adaptation to different mechanical environments with respect to the adjacent tibia. To test this hypothesis, serial-pQCT scans of the dominant fibulae and tibiae of 15/15 men/women chronically trained in long-distance running were compared with those of 15/15 untrained controls. When compared to controls, the fibulae of trained individuals had similar (distally) or lower (proximally) cortical area, similar moments of inertia (MI) for anterior-posterior bending (xMI) and lower for lateral bending (yMI) with a lower "shape-index" (yMI/xMI ratio) throughout, and higher resistance to buckling distally.

Differences in the relation between bone mineral content and lean body mass according to gender and reproductive status by age ranges.

The present study aims: (1) to explore the influence of lean mass (LM) on bone mineral content (BMC), (2) to investigate the pubertal influences on the BMC-LM relation, and (3) to perform Z-score charts of BMC-LM relation, stratified by gender and reproductive status categorized by age ranges. A cross-sectional analysis was conducted using 4001 healthy subjects between 7 and 90 years participating in the Health Workers Cohort Study. Of these, 720 participants were ≤ 19 years, 2417 were women ≥ 20 years, and 864 were men ≥ 20 years.

Multi-Scale Approach for the Evaluation of Bone Mineralization in Strontium Ranelate-Treated Diabetic Rats.

Long-term diabetes mellitus can induce osteopenia and osteoporosis, an increase in the incidence of low-stress fractures, and/or delayed fracture healing. Strontium ranelate (SrR) is a dual-action anti-osteoporotic agent whose use in individuals with diabetic osteopathy has not been adequately evaluated. In this study, we studied the effects of an oral treatment with SrR and/or experimental diabetes on bone composition and biomechanics.

Structural differences in cortical shell properties between upper and lower human fibula as described by pQCT serial scans. A biomechanical interpretation.

This study describes the structural features of fibula cortical shell as allowed by serial pQCT scans in 10/10 healthy men and women aged 20-40years. Indicators of cortical mass (mineral content -BMC-, cross-sectional area -CSA-), mineralization (volumetric BMD, vBMD), design (perimeters, thickness, moments of inertia -MIs-) and strength (Bone Strength Indices, BSIs; polar Strength-Strain Index, pSSI) were determined. All cross-sectional shapes and geometrical or strength indicators suggested a sequence of five different regions along the bone, which would be successively adapted to 1.

Imaging of the muscle-bone relationship.

Muscle can be assessed by imaging techniques according to its size (as thickness, area, volume, or alternatively, as a mass) and architecture (fiber length and pennation angle), with values used as an anthropometric measure or a surrogate for force production. Similarly, the size of the bone (as area or volume) can be imaged using MRI or pQCT, although typically bone mineral mass is reported. Bone imaging measures of mineral density, size, and geometry can also be combined to calculate bone's structural strength-measures being highly predictive of bone's failure load ex vivo.

Site and sex effects on tibia structure in distance runners and untrained people.

Purpose: The purpose was to study the relationship between mechanical environment and bone structure by comparing the tibia in people with different physical activities.

Materials And Methods: Indicators of bone mass (bone mineral content), bone material "quality" (cortical volumetric mineral density (vBMD)), and diaphyseal design (endocortical and periosteal perimeters (EcPm and PoPm, respectively), cortical thickness (CtTh), circularity, and bending and torsion cross-sectional moments of inertia (CSMIs)) were determined in serial peripheral quantitative computed tomography scans taken at 5% steps of the tibia in 40 voluntary men and women age 25-40 yr who were either physically inactive or experienced distance runners (n = 10-12 per group).

Results: Bone mass and design indicators were higher in runner than in nonrunner men, with a variable effect size along the tibia.

Structural analysis of the human tibia in men with spinal cord injury by tomographic (pQCT) serial scans.

Spinal cord injury (SCI), as a primarily neurological disorder that causes muscular atrophy, is well known to be associated with sub-lesional bone losses. These losses are more pronounced from epiphyseal than from diaphyseal regions. We hypothesized that this discrepancy may be explained by anatomical variation in endocortical circumference.

Structural analysis of the human tibia by tomographic (pQCT) serial scans.

This study analyses the evaluation of tomographic indicators of tibia structure, assuming that the usual loading pattern shifts from uniaxial compression close to the heel to a combined compression, torsion and bending scheme towards the knee. To this end, pQCT scans were obtained at 5% intervals of the tibia length (S5-S95 sites from heel to knee) in healthy men and women (10/10) aged 20-40 years. Indicators of bone mass [cortical area, cortical/total bone mineral content (BMC)], diaphyseal design (peri/endosteal perimeters, cortical thickness, circularity, bending/torsion moments of inertia - CSMIs), and material quality [(cortical vBMD (bone mineral density)] were determined.

Association between low lean body mass and osteoporotic fractures after menopause.

Objective: This study evaluated dual-energy x-ray absorptiometry-assessed whole-body bone-muscle relationship (bone mineral content/lean mass [BMC/LM]) as an indicator of its nonmechanical perturbations (ie, systemic) in pre- and postmenopausal women. A total of 3,205 women were studied, either healthy (no fracture [No Fx] groups, 1,035 premenopausal, 1,556 postmenopausal) or with recent fractures (Fx groups, 139 premenopausal, 475 postmenopausal) located at osteoporotic sites (hip, spine, long-bone metaphyses; Type II Fx, n = 386) or at other skeletal sites (Type I Fx, n = 228) to evaluate the impact of decreased muscle mass on fracture incidence before and after menopause.

Design: SD-scored graphs of BMC/LM proportionality were obtained from the No Fx groups as normal references.

Vertical jump performance after 90 days bed rest with and without flywheel resistive exercise, including a 180 days follow-up.

Muscle atrophy and neuromuscular de-conditioning occur in response to space flight and bed-rest. In this study, we investigated the efficacy of flywheel training to conserve jumping power and height during 90 days bed rest. Twenty-four young healthy men underwent strict bed-rest (-6 degrees head down tilt) for 90 days.

Reference charts for the relationships between dual-energy X-ray absorptiometry-assessed bone mineral content and lean mass in 3,063 healthy men and premenopausal and postmenopausal women.

Correlations between dual-energy X-ray absorptiometry (DXA)-assessed bone mineral content and lean mass (BMC-LM curves), and between BMC/LM ratio and age ([BMC/LM]-age curves), were analyzed in the whole body (WB), the upper limbs (ULs) and the lower limbs (LLs) of 3,063 healthy Hispanic adults. Groups of 472 men aged 25-87 years, 1,035 premenopausal (pre-MP) women aged 27-54 years, and 1,556 post-menopausal (post-MP) women aged 48-93 years were studied with a GE-Lunar DPX-Plus device. BMC-LM curves confirmed previous observations that BMC and LM masses always correlate linearly, with similar slopes within each region, but differing in intercepts according to gender and hormonal status.

Absorptiometric assessment of muscle-bone relationships in humans: reference, validation, and application studies.

This report summarizes some preliminary absorptiometric (DXA, QCT/pQCT) studies from our laboratory, supporting the following assumptions. 1. In Homo sapiens at all ages, natural proportionality between DXA-assessed bone mineral mass (bone mineral content, BMC) and muscle mass (lean mass, LM) of the whole body or limbs is specific for ethnicity, gender, and reproductive status, but not for body weight, height, or body mass index.

Novel experimental effects on bone material properties and the pre- and postyield behavior of bones may be independent of bone mineralization.

In this article, we summarize the results of six different tomographic/biomechanical rat studies involving hypophysectomy (Hx), ovariectomy, treatment with rhGH, olpadronate, alendronate, and toxic doses of aluminum and the development of a genetic diabetes in the eSS strain. All these conditions induced some interesting and rarely reported effects on postyield bone strength. These effects were generally related neither to the degree of mineralization or the elastic modulus of the bone tissue nor to the preyield behavior of the bones.

Biomechanical impact of aluminum accumulation on the pre- and post-yield behavior of rat cortical bone.

In order to analyze the effects on whole-bone behavior of aluminum accumulation, 14 rats, aged 90 days, received i.p. doses of 27 mg/day of elemental Al, as Al(OH)3, during 26 weeks, while 14 rats remained as controls.

Effects of hypophysectomy and recombinant human growth hormone on material and geometric properties and the pre- and post-yield behavior of femurs in young rats.

To study the musculoskeletal effects of hypophysectomy (Hx) and a partial replacement treatment with recombinant human growth hormone (rhGH) in rats, we determined the stiffness (elastic modulus, E) and volumetric BMD (vBMD) of cortical bone; the periosteal and endosteal perimeters, area and bending moment of inertia (xCSMI) of the cross sections, and the structural stiffness and pre- and post-yield strength of the femur diaphyses by pQCT and mechanical tests, and the gastrocnemius weight of rats that were either intact (n = 9) or Hx at 15 days of age (20). The latter were otherwise untreated (Hx controls, 4) or given 0.4 (8) or 2.

[Toward an anthropometric diagnosis of osteopenia and a biochemical diagnosis of osteoporoses].

The current (metabolic) conception of bone-weakening diseases regards bone strength as determined by a systemically-controlled "mineralized mass" which grows until it reaches a peak and then is lost at individually-specific rates. This concept disregards bone biomechanics. Skeletons are structures, it reaches of which depends on the stiffness and the spatial distribution rather than the volume of the calcified material.

Bone mass, bone strength, muscle-bone interactions, osteopenias and osteoporoses.

Densitometrically, the skeleton is currently conceived as 'a systemically regulated mass of mineralized material that is born, grows, reaches a more or less high peak, and then declines faster or slower as to develop a correspondingly high or low fracture risk'. Alternatively, from a biomechanical point of view, the skeleton can be conceived as 'a biomechanically-regulated structure that can be systemically disturbed (in the cybernetic sense), the strength of which depends on the intrinsic stiffness (material properties) and the spatial distribution (architectural properties) of the mineralized tissue'. The biomechanical feedback system involved (bone 'mechanostat') would not control bone mass to optimize bone strength; it would rather control bone material quality and architecture (through a modulation of bone modeling and remodeling) in order to optimize bone stiffness.