Hormonal influences on the muscle-bone feedback system: A perspective
ABSTRACT Hormones, muscle and bone tissues have co-existed virtually during the whole evolution of vertebrates, and it is obvious that they constitute a complex system able to cope with needs and challenges arising from a variety of physiological and locomotive needs. All body movements are produced by co-ordinated contractions of skeletal muscles, while consequent dynamic muscle work provides the fundamental source of mechanical loading to the skeleton. Mechanical competence of the skeleton is principally maintained by a mechanosensory feedback system that senses the loading-induced deformations within the bones and maintains the skeletal rigidity through structural adaptation. In contrast to the prevalent view suggesting a modulatory effect of hormones on the sensitivity of the mechanosensory system, a new conceptual scheme is proposed. In particular, it is argued that the mechanical and hormonal functions in the skeleton are fundamentally independent but can be seemingly interactive through hormonally-induced modifications in the bone structure, those basically forming a mineral reservoir for maintenance of physiological homeostasis. Whenever needed, utilization of this strategically placed reservoir would not essentially compromise the mechanical competence and locomotive capability of the skeleton. Although plausible, the present view is necessarily speculative and awaits corroborative experimental evidence.
Full-textDOI: · Available from: Harri Sievänen, Dec 26, 2013
- SourceAvailable from: Timo RantalainenTheoretical Biomechanics, 11/2011; , ISBN: 978-953-307-851-9
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ABSTRACT: Genetic study can provide insight into the biologic mechanisms underlying inter-individual differences in susceptibility to (or resistance to) organisms' aging. Recent advances in molecular genetics and genetic epidemiology provide the necessary tools to perform a study of the genetic sources of biological aging. However, to be successful, the genetic study of a complex condition requires a heritable phenotype to be developed and validated. Genome-wide association studies offer an unbiased approach to identify new candidate genes for human diseases. It is hypothesized that convergent results from multiple aging-related traits will point out the genes responsible for the general aging of the organism. This perspective focuses on the musculoskeletal aging as an example of an approach to identify a downstream common pathway that summarizes aging processes. Since the musculoskeletal traits are linked to the state of many vital functions, disability, and ultimately survival rates, we postulate that there is significance in studying musculoskeletal aging. Construction of an integrated phenotype of aging can be achieved based on shared genetics among multiple musculoskeletal biomarkers. Valid biomarkers from other systems of the organism should be similarly explored. The new composite aging score needs to be validated by determining whether it predicts all-cause mortality, incidences of major chronic diseases, and disability late in life. Comprehensive databases on biomarkers of musculoskeletal aging in multiple large cohort studies, along with information on various health outcomes, are needed to validate the proposed measure of biological aging.Age 03/2011; 33(1):49-62. DOI:10.1007/s11357-010-9159-3 · 3.45 Impact Factor
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ABSTRACT: The strong association between body mass and skeletal robusticity has been attributed to increasing skeletal loading with increasing mass. However, it is unclear whether body mass is merely a coarse substitute for bone loading rather than a true independent predictor of bone strength. As indices of neuromuscular performance, impulse and peak power were determined from vertical ground reaction force during a maximal counter movement jump test in 221 premenopausal and 82 postmenopausal women. Bone compressive (BSI(d) g(2)/cm(4)) and bending (SSImax(mid) mm(3)) strength indices were measured with peripheral quantitative computed tomography (pQCT) at the distal ((d)) and midshaft ((mid)) sites of the tibia. A two-step forced regression model for predicting bone strength indices was constructed. Age, height and body mass were entered first, followed by impulse as an indicator of skeletal loading. The basic model explained 14% (P<0.001) of the variance in BSI(d) in the premenopausal group and 16% (P=0.004) in the postmenopausal group, and 32% (P<0.001) and 25% (P<0.001) of the variance in SSImax(nud) respectively. Entering impulse into the model increased the explanatory power by 9% (P<0.001) and 7% (P<0.001) for BSI(d) and by 8% (P<0.001) and 12% (P<0.001) for SSImax(mid). Furthermore, impulse replaced body mass as an independent significant factor explaining the variance in bone strength. These results indicate that neuromuscular performance should be measured and preferred over body mass in models predicting skeletal robusticity.Bone 04/2010; 46(4):964-9. DOI:10.1016/j.bone.2010.01.002 · 4.46 Impact Factor