Habitual levels of vigorous physical activity as measured by accelerometry are positively related to cortical bone mass in adolescence, whereas no association is seen with moderate or light activity

Bone ◽  
2010 ◽  
Vol 47 ◽  
pp. S103-S104
Author(s):  
A. Sayers ◽  
J.H. Tobias
Keyword(s):  
Physical Activity ◽  
Bone Mass ◽  
Cortical Bone ◽  
Vigorous Physical Activity ◽  
Light Activity ◽  
Cortical Bone Mass

scholarly journals Influence of a School-based Physical Activity Intervention on Cortical Bone Mass Distribution: A 7-year Intervention Study

2016 ◽  
Vol 99 (5) ◽  
pp. 443-453 ◽  
Author(s):  
Jesper Fritz ◽  
Rachel L. Duckham ◽  
Timo Rantalainen ◽  
Björn E. Rosengren ◽  
Magnus K. Karlsson ◽  
...  
Keyword(s):  
Physical Activity ◽  
Bone Mass ◽  
Cortical Bone ◽  
Mass Distribution ◽  
Intervention Study ◽  
Physical Activity Intervention ◽  
School Based ◽  
Cortical Bone Mass

scholarly journals The myokine irisin increases cortical bone mass

2015 ◽  
Vol 112 (39) ◽  
pp. 12157-12162 ◽  
Author(s):  
Graziana Colaianni ◽  
Concetta Cuscito ◽  
Teresa Mongelli ◽  
Paolo Pignataro ◽  
Cinzia Buccoliero ◽  
...  
Keyword(s):  
Physical Activity ◽  
Adipose Tissue ◽  
Bone Mass ◽  
Cortical Bone ◽  
Low Dose ◽  
Bending Strength ◽  
Molecular Entity ◽  
Weekly Dose ◽  
Mineral Density ◽  
Cortical Bone Mass

It is unclear how physical activity stimulates new bone synthesis. We explored whether irisin, a newly discovered myokine released upon physical activity, displays anabolic actions on the skeleton. Young male mice were injected with vehicle or recombinant irisin (r-irisin) at a low cumulative weekly dose of 100 µg kg−1. We observed significant increases in cortical bone mass and strength, notably in cortical tissue mineral density, periosteal circumference, polar moment of inertia, and bending strength. This anabolic action was mediated primarily through the stimulation of bone formation, but with parallel notable reductions in osteoclast numbers. The trabecular compartment of the same bones was spared, as were vertebrae from the same mice. Higher irisin doses (3,500 µg kg−1 per week) cause browning of adipose tissue; this was not seen with low-dose r-irisin. Expectedly, low-dose r-irisin modulated the skeletal genes, Opn and Sost, but not Ucp1 or Pparγ expression in white adipose tissue. In bone marrow stromal cell cultures, r-irisin rapidly phosphorylated Erk, and up-regulated Atf4, Runx2, Osx, Lrp5, β-catenin, Alp, and Col1a1; this is consistent with a direct receptor-mediated action to stimulate osteogenesis. We also noted that, although the irisin precursor Fndc5 was expressed abundantly in skeletal muscle, other sites, such as bone and brain, also expressed Fndc5, albeit at low levels. Furthermore, muscle fibers from r-irisin–injected mice displayed enhanced Fndc5 positivity, and irisin induced Fdnc5 mRNA expression in cultured myoblasts. Our data therefore highlight a previously unknown action of the myokine irisin, which may be the molecular entity responsible for muscle–bone connectivity.

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