Local bone mineral response to brief exercise that stresses the skeleton.

Beverly, Michael; Rider, T A; Evans, M.; Smith, R. W.

doi:10.1136/bmj.299.6693.233

Cited by 108 publications

(33 citation statements)

References 9 publications

(2 reference statements)

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“…The effect of physical activity appears to be primarily local, as confirmed by studies showing greater hypertrophy in the dominant arms of tennis players (Beverly, Rider, Evans, & Smith, 1989;Huddleston, Rockwell, Kulund, & Harrison, 1980;H.H. Jones, Priest, & Hayes, 1977;Montoye, Smith, Fardon, & Howley, 1980).…”

Section: Effects Of Exercise On Bone Mineral Densitymentioning

confidence: 73%

Exercise: A Prevention and Treatment for Osteoporosis and Injurious Falls in the Older Adult

Smith¹,

Tommerup²

1995

Journal of Aging and Physical Activity

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Osteoporosis is a major public health problem in persons over the age of 65, and it leads to approximately 250,000 hip fractures per year. Contributing risk factors for osteoporosis and hip fractures in the aging population include insufficient nutrient intake, inadequate dietary calcium, muscular weakness, decreased physical activity, and changes in hormonal homeostasis. Physical activity especially plays an important role in the prevention of falls and fractures. Physically active older adults with greater muscular strength experience fewer and less injurious falls than older people who are inactive. The effects of physical activity on bone strength and metabolism have only recently been investigated. When bone is mechanically stimulated, the cells respond by producing many local hormones and growth factors, including prostaglandin E, (PGE$), a mediator of bone modeling and remodeling. Current research continues to show that physical activity significantly affects the geometry and architecture of bone as well as increasing bone mineral density, all of which contribute to an increase in bone strength.Key Words: physical activity, osteoporosis, bone, mechanical loading Osteoporosis and fractures resulting from falls are a major public health hazard for older adults. Evidence is beginning to emerge that physical exercise can both strengthen bone integrity and reduce risk factors for falls (such as muscle weakness, poor balance, and slow gait velocity). This review will discuss current knowledge in the following areas: (a) general bone metabolism, (b) prevalence of and risk factors for falls and fractures, (c) the effects of exercise on risk factors for falls and fractures, especially bone mineral density, and (d) cellular hypotheses for the mechanisms of the bone response to exercise. Overview of Bone MetabolismThe skeleton not only provides structural support but also serves as a mineral reservoir. Skeletal architecture, geometry, and bone mineral content respond to hormonal and mechanical homeostatic mechanisms through the processes of The authors are with the

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Section: Effects Of Exercise On Bone Mineral Densitymentioning

confidence: 73%

Exercise: A Prevention and Treatment for Osteoporosis and Injurious Falls in the Older Adult

Smith¹,

Tommerup²

1995

Journal of Aging and Physical Activity

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“…Aloia et al [30] found total body calcium (an index of bone) and total body potassium (an index of lean tissue) to be significantly and positively related. Other studies have reported increased muscular strength (which is related to muscle mass) to be positively associated with bone density [31][32][33][34].…”

Section: Discussionmentioning

confidence: 99%

Regional and total body bone mineral content, bone mineral density, and total body tissue composition in children 8?16 years of age

et al. 1993

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Normative values for total body bone mineral content (TBBM) and total body bone mineral density (TBMD) were derived from measurements on 234 children 8-16 years of age. In addition, bone mineral content (BMC) and bone mineral density (BMD) values for selected regions of interest and soft tissue (bone free lean and fat) for the total body are presented. Bone mineral and soft tissue values were determined by dual energy X-ray absorptiometry (DXA) using a Hologic QDR-2000 in the array mode. Results of a stepwise multiple regression analysis revealed a significant correlation between bone-free lean tissue (BFLT) and BMD (r2 = 0.80) in girls. Adding age to the equation accounted for an additional 2% of the variance (P < 0.05) and height accounted for another 1% of the variance (P < 0.05). Body weight and fat tissue (FT) did not account for any additional variance. In boys BFLT correlated significantly with BMD (r2 = 0.75; P < 0.05); none of the other predictor variables accounted for additional variance. No significant differences were found in TBBM or TBMD between boys and girls at any age. There was a significant overall gender effect for only three regions of interest. Boys had greater BMC in the head region and had greater BMD in the upper limbs, but post hoc analysis revealed no significant differences for any specific age groups. Girls had greater overall BMD in the pelvis, but this difference was only significant at the 15-16-year age group. The changes in BFLT and FT over the age ranges were consistent with the growth literature.(ABSTRACT TRUNCATED AT 250 WORDS)

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“…One unifying explanation for the high scaling exponents and the difference in Q i between mammals and reptiles is the requirement for bone remodelling in response to stresses put on the bones during locomotion. It is very well established that mammals increase remodelling of their bones in response to mechanical loading during exercise [24,25], and measurements indicate that this requires increased blood flow in long bones [26]. Remodelling increases cellular activity within the bone cortex, presumably increasing metabolic rate and thus accounting for the increased oxygenation [11].…”

Section: Discussionmentioning

confidence: 99%

Blood flow to long bones indicates activity metabolism in mammals, reptiles and dinosaurs

et al. 2011

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The cross-sectional area of a nutrient foramen of a long bone is related to blood flow requirements of the internal bone cells that are essential for dynamic bone remodelling. Foramen area increases with body size in parallel among living mammals and non-varanid reptiles, but is significantly larger in mammals. An index of blood flow rate through the foramina is about 10 times higher in mammals than in reptiles, and even higher if differences in blood pressure are considered. The scaling of foramen size correlates well with maximum whole-body metabolic rate during exercise in mammals and reptiles, but less well with resting metabolic rate. This relates to the role of blood flow associated with bone remodelling during and following activity. Mammals and varanid lizards have much higher aerobic metabolic rates and exercise-induced bone remodelling than non-varanid reptiles. Foramen areas of 10 species of dinosaur from five taxonomic groups are generally larger than from mammals, indicating a routinely highly active and aerobic lifestyle. The simple measurement holds possibilities offers the possibility of assessing other groups of extinct and living vertebrates in relation to body size, behaviour and habitat.Keywords: metabolic rate; blood flow; bone remodelling; nutrient foramen; allometry INTRODUCTIONThe size of blood vessels is dynamically variable, responding to the blood flow requirements through them. Vessels throughout the body react specifically to greater blood pressures by thickening and strengthening the walls, and to greater shear stress (related to the velocity of the blood) by increasing circumference [1,2]. Organs that have higher metabolic rates require higher flow rates and therefore have larger blood vessels that service them. To test the hypothesis that differences in blood perfusion rates reflect differences in metabolic capacity between species, this study examines the correlations between femoral nutrient foramen size, bone volume, body mass and resting and maximum metabolic rates in living mammals and reptiles. As bones are the only tissues remaining from non-avian dinosaurs, the relationships between nutrient foramina size and metabolic capacity developed for mammals and reptiles can indicate the levels of activity and metabolic status of dinosaurs.Long bones of all amniotes, comprising the reptiles, mammals and birds, receive blood from three sources: (i) nutrient vessels, (ii) metaphyseal and epiphyseal vessels that combine after the cartilaginous growth plate is closed and (iii) periosteal vessels [3]. The nutrient system contributes around 50 -70% of the blood supply

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Local bone mineral response to brief exercise that stresses the skeleton.

Cited by 108 publications

References 9 publications

Exercise: A Prevention and Treatment for Osteoporosis and Injurious Falls in the Older Adult

Exercise: A Prevention and Treatment for Osteoporosis and Injurious Falls in the Older Adult

Regional and total body bone mineral content, bone mineral density, and total body tissue composition in children 8?16 years of age

Blood flow to long bones indicates activity metabolism in mammals, reptiles and dinosaurs

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