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It has been theorized that muscles generate more force on bone than body weight alone and therefore it is likely that muscle contraction drives and sustains bone adaptation (Frost 1999). Purpose: To investigate the relationship between the timing and tempo of peak growth velocities of lean tissue (LT) and bone mineral content (BMC) in boys and girls at three sites using data derived from individual growth curves. Methods: 72 boys and 70 girls were fitted with growth curves that had a distinguishable peak. Height and weight were measured for each participant and tissue assessment was performed annually using DXA. Factorial ANOVAs were completed to analyse data for differences in age, while forward regression analyses was used between LT and BMC. Results: The peak growth velocity for lean occurred significantly (P<0.05) earlier than the peak growth velocity for bone at all locations except the legs. There was a difference (P<0.001) between genders in the age of peak for both lean tissue and bone tissue at all locations with females peak growth occurring before that of males. When aligned by PHV a significant difference (P<0.05) in the timing of PBMCV was found between the arms and the legs with the peak in bone growth in the legs occurring significantly before peak bone growth in the arms. PLTV was independently associated with PBMCV at the arms (r2= .71, p<0.001), legs (r2= .53, p<0.001) and trunk (r2= .52, p<0.001). Conclusion: In conclusion, LT growth precedes BMC growth and after controlling for gender, size and maturity the magnitude of LT growth is associated with BMC growth. The findings of this study are in support the Muscle-bone Unit (Frost and Schoenau, 2000), which theorizes that localised muscle action is a driving force for bone growth. Future studies are needed to analyse bone strength as it relates to local muscle strength and usage while controlling for confounding variables.

It has been theorized that muscles generate more force on bone than body weight alone and therefore it is likely that muscle contraction drives and sustains bone adaptation (Frost 1999). Purpose: To investigate the relationship between the timing and tempo of peak growth velocities of lean tissue (LT) and bone mineral content (BMC) in boys and girls at three sites using data derived from individual growth curves. Methods: 72 boys and 70 girls were fitted with growth curves that had a distinguishable peak. Height and weight were measured for each participant and tissue assessment was performed annually using DXA. Factorial ANOVAs were completed to analyse data for differences in age, while forward regression analyses was used between LT and BMC. Results: The peak growth velocity for lean occurred significantly (P<0.05) earlier than the peak growth velocity for bone at all locations except the legs. There was a difference (P<0.001) between genders in the age of peak for both lean tissue and bone tissue at all locations with females peak growth occurring before that of males. When aligned by PHV a significant difference (P<0.05) in the timing of PBMCV was found between the arms and the legs with the peak in bone growth in the legs occurring significantly before peak bone growth in the arms. PLTV was independently associated with PBMCV at the arms (r2= .71, p<0.001), legs (r2= .53, p<0.001) and trunk (r2= .52, p<0.001). Conclusion: In conclusion, LT growth precedes BMC growth and after controlling for gender, size and maturity the magnitude of LT growth is associated with BMC growth. The findings of this study are in support the Muscle-bone Unit (Frost and Schoenau, 2000), which theorizes that localised muscle action is a driving force for bone growth. Future studies are needed to analyse bone strength as it relates to local muscle strength and usage while controlling for confounding variables.

Non-invasive estimates of bone quality are of great interest as they could potentially improve the diagnosis and treatments for bone disorders, such as osteoporosis, and could aid in preoperative planning of surgical interventions, improving patient outcomes in orthopaedic trauma. Quantitative computed tomography (QCT) is currently being investigated as a method of estimating structural bone mineral content (sBMC) and, thus, bone quality. However, the reported correlations between QCT and sBMC have been variable and the relationships reported between sBMC and the apparent elastic modulus (E*) of bone have been even more variable. A series of investigations are presented, relating QCT, sBMC, apparent density and the E* of bone. These studies were performed with the ultimate objective of determining the appropriateness of QCT as a predictor of the E* of bone and whether the E* of bone could be predicted from information regarding the sBMC and apparent density. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2008-01-31 22:00:08.77 / This work was funded by the Canadian Institutes of Health Research.

The purpose of this study was to determine whether there are differences in bone mineral content and density between paralyzed and nonparalyzed sides of patients who had sustained strokes associated with unilateral muscle weakness, to determine the relationship between duration of stroke and degree of demineralization and to compare the degree of demineralization in upper and lower limbs. The bone mineral content and density were measured by dual photon absorptiometry (high resolution scanning mode, Lunar DP4) in ambulant patients with a history of single completed strokes associated with unilateral weakness. The bone mineral content and density of each limb was determined by the region of interest analysis program. In the 30 patients included in this study, the bone mineral content and density were significantly less on the paralyzed than on the nonparalyzed side. The degree of demineralization was more pronounced in the upper than in the lower limbs. The mean percentage differences in bone mineral content and density between paralyzed and nonparalyzed arms were 13.8% (P < 0.00001) and 7.95% (P = 0.0003), respectively, and between paralyzed and nonparalyzed legs the differences were 4.5% (P = 0.0012) and 3.42% (P = 0.0028), respectively. A better correlation was noted between the time elapsed since the stroke and the degree of demineralization in the upper limbs (r = 0.75, P < 0.0001), than in the lower limbs (r = 0.60, P = 0.0004). In conclusion, patients who have strokes associated with muscle weakness are at an increased risk of developing osteoporosis on the paralyzed side and particularly in the upper limbs.

The objectives of this research were to evaluate non-invasive measures of bone mineral content (BMC) and bone mineral density (BMD) as rapid, on-farm tools to assess phosphorus (P) status in dairy cows. In addition, the effects of parity and stage of lactation on measures of BMC of the fused 3rd and 4th metacarpal bone and of caudal vertebrae 14 and 15 were assessed. The caudal vertebrae and right front metacarpal (sample pairs) were excised from 107 Holstein cull cows following slaughter. Parity, age, and days in milk (DIM) of the donor animal were obtained for 43 pairs of samples. Samples were grouped by parity (1, 2, 3, and >4) and stage of lactation (Stage 1 = < 90 DIM, Stage 2 = > 90 and < 150 DIM, Stage 3 = >150 and < 250 DIM and Stage 4 = > 250 DIM). Samples were analyzed for BMC and BMD with dual energy X-ray absorptiometry (DXA), BMC with radiographic photometry (RP), breaking strength with mechanical methods, and mineral content with chemical procedures. Estimates of BMC obtained with RP and DXA were poorly related to chemical measures of actual BMC and to measures of breaking strength. In caudal vertebrae 14 and 15, increasing stage of lactation decreased energy to peak load with the lowest values observed in late lactation. Stage of lactation had no effect on BMC measured chemically in the caudal vertebrae or metacarpal. Parity did not affect breaking strength of the metacarpal or caudal vertebrae or total ash or P content of any bone. Results indicated that imaging techniques are not useful measures of BMC in mature dairy cattle. / Master of Science

The dramatic rise in health care and economic costs as well as increases in morbidity and mortality related to lifestyle behaviors and non-communicable diseases have resulted in an increasing emphasis on research and intervention initiatives aimed at primary prevention. As there is growing evidence that the antecedents of adult diseases such as obesity and osteoporosis have roots in early childhood, physical activity interventions in early childhood (4 to 6 years of age), which has been identified as a critical period, may influence the development of fat and bone mass at this young age and have a potential impact on adolescent and young adult health status and thus improve population health. The intent of this study was to investigate the effects of structured physical activity, specifically early involvement in gymnastics, on early childhood body composition development.<P>Sixty three (25 male and 38 female) 4 to 6 year old children participating in gymnastics programs were compared to 95 control (49 male and 46 female) children. Anthropometric measurements included height, weight, BMI, waist circumference, and skinfold thickness. Dual energy x-ray absorptiometry (DXA) was used to measure whole body bone density and fat mass. Physical activity, physical inactivity, dietary intake, and birth weight of the participants as well as parental heights and weights were also obtained. <P>No significant differences were found, at any age, between the groups in height, weight, BMI, waist circumference, skinfold thickness, physical activity, physical inactivity, dietary intakes, and birth weight or in parental heights and weights (p>0.05). Additionally, there were no significant differences in fat and bone parameters once the confounders of age and size were controlled (p>0.05). <P>This investigation found that young children entering a gymnastics program did not differ in either bone mass or fat mass compared to controls. This was surprising as differences in these parameters have been found in adolescent gymnasts. Thus my results indicate that the potential effects of gymnastics training may have not yet manifested themselves. To answer this question longitudinal measures are required to ascertain whether the body composition differences observed in adolescent gymnasts are due to prolonged exposure to gymnastics involvement.

The dramatic rise in health care and economic costs as well as increases in morbidity and mortality related to lifestyle behaviors and non-communicable diseases have resulted in an increasing emphasis on research and intervention initiatives aimed at primary prevention. As there is growing evidence that the antecedents of adult diseases such as obesity and osteoporosis have roots in early childhood, physical activity interventions in early childhood (4 to 6 years of age), which has been identified as a critical period, may influence the development of fat and bone mass at this young age and have a potential impact on adolescent and young adult health status and thus improve population health. The intent of this study was to investigate the effects of structured physical activity, specifically early involvement in gymnastics, on early childhood body composition development.<P>Sixty three (25 male and 38 female) 4 to 6 year old children participating in gymnastics programs were compared to 95 control (49 male and 46 female) children. Anthropometric measurements included height, weight, BMI, waist circumference, and skinfold thickness. Dual energy x-ray absorptiometry (DXA) was used to measure whole body bone density and fat mass. Physical activity, physical inactivity, dietary intake, and birth weight of the participants as well as parental heights and weights were also obtained. <P>No significant differences were found, at any age, between the groups in height, weight, BMI, waist circumference, skinfold thickness, physical activity, physical inactivity, dietary intakes, and birth weight or in parental heights and weights (p>0.05). Additionally, there were no significant differences in fat and bone parameters once the confounders of age and size were controlled (p>0.05). <P>This investigation found that young children entering a gymnastics program did not differ in either bone mass or fat mass compared to controls. This was surprising as differences in these parameters have been found in adolescent gymnasts. Thus my results indicate that the potential effects of gymnastics training may have not yet manifested themselves. To answer this question longitudinal measures are required to ascertain whether the body composition differences observed in adolescent gymnasts are due to prolonged exposure to gymnastics involvement.

Unauthorized reproduction of this 8 article is prohibited. Objective:To examine differences in bone mass between children and adolescents swimming competitively at nonelite levels (locally and regionally) and nonathletes and to assess changes in bone mass in these 2 groups over 24 months after taking into consideration several known confounders of bone mass.Design:Observational prospective study.Participants:White nonelite swimmers (n=128) and nonathletes (n=106) 8 to 18 years of age from Memphis, Tennessee, USA.Main Outcome Measures:Participants underwent dual-energy x-ray absorptiometry to assess total body and hip bone mineral content (BMC) at baseline and 12 and 24 months later.Results:At baseline, swimmers had 4.2% and 6.1% higher adjusted BMC for the total body and hip, respectively, compared with nonathletes (P values < 0.027). Averaging across assessment points, swimmers had 73.5 and 2.2 g higher BMC for the total body and hip, respectively, than nonathletes. Although there was a significant annual increase in total body and hip BMC in both groups (33.5 and 0.7 g, respectively), there was no difference in annualized bone accrual between swimmers and nonathletes for either total body BMC (swim by time effect; P=0.213) or hip BMC (P=0.265).Conclusions:Competitive swimming at nonelite levels during childhood and adolescence does not seem to compromise bone accrual.