Weight-bearing Physical Activity Research Articles

A family-centered lifestyle intervention to improve body composition and bone mass in overweight and obese children 6 through 8 years: a randomized controlled trial study protocol

BackgroundChildhood obesity gives rise to health complications including impaired musculoskeletal development that associates with increased risk of fractures. Prevention and treatment programs should focus on nutrition education, increasing physical activity (PA), reducing sedentary behaviours, and should monitor bone mass as a component of body composition. To ensure lifestyle changes are sustained in the home environment, programs need to be family-centered. To date, no study has reported on a family-centered lifestyle intervention for obese children that aims to not only ameliorate adiposity, but also support increases in bone and lean muscle mass. Furthermore, it is unknown if programs of such nature can also favorably change eating and activity behaviors. The aim of this study is to determine the effects of a 1 y family-centered lifestyle intervention, focused on both nutrient dense foods including increased intakes of milk and alternatives, plus total and weight-bearing PA, on body composition and bone mass in overweight or obese children.Methods/designThe study design is a randomized controlled trial for overweight or obese children (6–8 y). Participants are randomized to control, standard treatment (StTx) or modified treatment (ModTx). This study is family-centred and includes individualized counselling sessions on nutrition, PA and sedentary behaviors occurring 4 weeks after baseline for 5 months, then at the end of month 8. The control group receives counselling at the end of the study. All groups are measured at baseline and every 3 months for the primary outcome of changes in body mass index Z-scores. At each visit blood is drawn and children complete a researcher-administered behavior questionnaire and muscle function testing. Changes from baseline to 12 months in body fat (% and mass), waist circumference, lean body mass, bone (mineral content, mineral density, size and volumetric density), dietary intake, self-reported PA and sedentary behaviour are examined.DiscussionThis family-centered theory-based study permits for biochemical and physiological assessments. This trial will assess the effectiveness of the intervention at changing lifestyle behaviours by decreasing adiposity while enhancing lean and bone mass. If successful, the intervention proposed offers new insights for the management or treatment of childhood obesity.Trial registrationClinicalTrials.gov, NCT01290016.

Exercise, bone and nutrition.

Predisposition to poor skeletal health resulting in osteoporotic fracture is a major public health problem, the future economical impact of which is likely to be phenomenal. Two mechanisms principally determine adult bone health: (1) maximum attainment of peak bone mass (PBM); (2) the rate of bone loss with advancing age. Both aspects are regulated by a combination of endogenous and exogenous factors, and although genetic influences are believed to account for up to 75% of the variation in bone mass, there is still room for modifiable factors to play a vital role. Weight-bearing physical activity is beneficial to the skeleton, but clarification of the exact type, intensity and duration required for optimum bone mass is needed. Excessive levels of exercise, which result in amenorrhoea, are detrimental to skeletal health. The importance of Ca to bone remains controversial. There is evidence that Ca is effective in reducing late post-menopausal bone loss, but more research is required on the long-term benefit of increased Ca intake on PBM attainment. Vitamin D 'insufficiency' appears to be widespread amongst population groups and is an area of considerable public health concern. The role of other micronutrients on bone metabolism remains to be fully quantified, but data from a combination of experimental, clinical and observational studies suggest a positive link between alkaline-forming foods and indices of bone health. The influence of nutrient-gene interactions on the skeleton requires further elucidation, but it may be useful in the future to target nutrition advice at those individuals who are genetically susceptible to osteoporosis.

Bone Mineral Density and Body Composition of Adult Premenopausal Women with Three Levels of Physical Activity

Weight-bearing and resistance physical activities are recommended for osteoporosis prevention, but it is unclear whether an intensity level above current recommendations has a positive effect on adult premenopausal women. Body composition and bone mineral density (BMD) by DXA were compared in three groups of women as follows: Sedentary, Maintenance exercise, and federated Sport Team (n = 16 for each group). Physical activity was estimated from the International Physical Activity Questionnaire (IPAQ). The groups did not differ in age, height, weight, or body mass index. Bone mineral content and non-fat soft tissue mass were higher and fat mass was lower in the Sport Team group than in the other groups. The same was true for BMD of total skeleton, lumbar spine, femoral neck, and total hip. A test for linear trend of body composition and BMD showed significant results when including all three groups. Simple and multiple regression analyses showed significant associations between physical activity level (or alternatively, years of participation in programmed physical activity) and bone mass measures at all sites except for the middle third of radius. It is concluded that a level of physical activity higher than that usually recommended benefits bone health in adult premenopausal women.

Osteoporosis prevention and motivation for weight-bearing physical activity and calcium consumption

Osteoporosis prevention and motivation for weight-bearing physical activity and calcium consumption

Bone structure and geometry in young men: The influence of smoking, alcohol intake and physical activity

BackgroundThe development of osteoporosis is influenced by peak bone mass attained in youth — the influence of lifestyle factors upon which is poorly described, especially amongst males. We sought to address this issue in a large scale study. MethodsHip bone mineral density (dual X-ray absorptiometry, DXA), bone microarchitecture (calcaneal quantitative ultrasound, QUS) and femoral geometry (magnetic resonance imaging, MRI) were characterised in 723 healthy male military recruits (mean±S.E. age 19.92±0.09years [range 16–18years], height 177.67±0.24cm, weight 73.17±0.37kg) on entry to UK Army training. Association was sought with prior physical activity, smoking status and alcohol intake. ResultsDXA measures were made in 651, MRI measures in 650, and QUS measures in 572 recruits. Increasing levels of weight-bearing physical activity enhanced periostial bone apposition, increases in both total hip and femoral neck bone mineral density (BMD; p≤0.0001 in both cases), and cortical [p<0.0001] and periostial bone volumes [p=0.016]. Smoking habit was associated with preserved bone geometry, but worse BMD [p=0.0001] and QUS characteristics [p≤0.0005]. Moderate alcohol consumption was associated with greater BMD [p≤0.015]. ConclusionsWhilst exercise (and perhaps moderate alcohol intake) is beneficial to bone morphometry, smoking is detrimental to bone mineral density in young males notable for the likely short duration of smoking to influence skeletal properties. However, differences in socio-economic status, lifestyle and related environmental factors may to some extent confound our results.

Physical Activity Increases Bone Mineral Density in Children with Type 1 Diabetes

Osteoporosis is a growing health problem in patients with type 1 diabetes mellitus (T1DM). The aim of this study was to determine the effects of a 9-month weight-bearing physical activity program on bone mineral density (BMD) and bone biomarkers in T1DM compared with healthy children. This was a randomized controlled trial including 27 diabetic and 32 healthy children (mean age = 10.5 ± 2.5 yr). Both T1DM and healthy participants were randomized to either an exercise or a control group (i.e., four groups). At baseline and 9 months, total body (TB), lumbar spine (LS2-LS4), femoral neck, and greater trochanter areal BMD (aBMD) and serum bone biomarkers (osteocalcin, type 1 collagen cross-linking) were measured. The intervention consisted of two 90-min sessions per week of weight-bearing physical activity (ball games, jumping, rope skipping, and gymnastics). Baseline variables were similar among groups. At 9 months, changes in TB (T1DM = 0.035 ± 0.022 g·cm(-2), healthy = 0.031 ± 0.017 g·cm(-2)) and LS2-LS4 (T1DM = 0.046 ± 0.038 g·cm(-2), healthy = 0.063 ± 0.034 g·cm(-2)) aBMD were statistically significant in the intervention groups and of similar magnitude between T1DM and healthy subjects. The level of type 1 collagen cross-linking (T1DM = -0.12 ± 0.32 ng·mL(-1), healthy = -0.36 ± 0.11 ng·mL(-1)) decreased in the intervention groups but was not associated with TB aBMD changes. Regular weight-bearing physical activity (180 min·wk(-1), including ball games, jumping activities, and gymnastics) improves total and LS2-LS4 bone mineral accretion in children with T1DM, in a similar magnitude to healthy subjects. We conclude that children with T1DM should be encouraged to practice regular physical activity to enhance peak bone mass and prevent osteoporosis later in life.

Predictors of bone mineral density in a convenience sample of young Caucasian adults living in southern Ontario

Osteoporosis is a major public health concern in Canada and worldwide. Although much is known about bone health in older adults, little is known about bone health in young, healthy Canadian men and women. The objectives of this research were to describe bone mineral density (BMD) of young, healthy adults living in southern Ontario, Canada, and to identify predictors of BMD in this population. Two-hundred and fifty-eight Caucasian men and women aged 18-33 years completed health and physical activity questionnaires along with a calcium and vitamin D specific food frequency questionnaire. Height and mass were measured. BMD of the total hip, femoral neck, spine, and total body was measured using dual energy X-ray absorptiometry. Among men, body mass, weight-bearing physical activity, and calcium intake were significant predictors of BMD. Among women, body mass, calcium intake, and family history of osteoporosis significantly predicted log BMD. The predictors of BMD in young Canadian men and women identified in this study may inform the development of longitudinal studies designed to examine the influence of lifestyle factors on BMD in young adults.

Bone mineral density and body composition of South African cricketers

Mechanical loading associated with weight-bearing physical activity has been positively associated with bone mineral density in athletes participating in various sports. The aim of this study was to compare the body composition and bone mineral density of South African male cricketers to controls. Whole body (WB), femoral neck (FN), proximal femur (PF) and lumbar spine (LS) BMD, as well as whole body fat mass (WBFM) and lean mass (WBLM) were measured, using dual-energy X-ray absorptiometry (DXA), on 34 high-performance (senior provincial and national level) cricketers and 23 physically active controls between the ages of 16 and 34years. Cricketers were significantly younger, taller, and had greater WBLM and WBBMC compared to the controls. LS, PF and FN BMD were higher in the cricketers and controls before and after adjusting for age and height. WBBMD was significantly lower in the spin bowlers compared to the batsmen and fast bowlers, after adjusting for age and height; however, there were no differences at the BMD sites between the groups. Bone mineral density at the lumbar spine and hip sites was significantly greater in the cricketers compared to the controls, suggesting that the mechanical loading associated with cricket is beneficial for bone mineral density.

The role of lean body mass and physical activity in bone health in children

In the context of physical education curricula, markers of physical fitness (e.g., aerobic capacity, muscular strength, flexibility, and body mass index or body fat) are usually evaluated in reference to health standards. Despite their possible mediating role in the relationship between weight-bearing or muscle forces and features of bone tissue, these attributes of fitness may not be the most relevant to predict skeletal health. It is therefore important to analyze the relative contribution of these factors to the variability in bone tissue of different parts of the skeleton, and to analyze it by gender, as sensitivity to mechanical loading can diverge for boys and girls. We compared the effects of habitual physical activity (PA) and lean mass, as surrogates of weight-bearing and muscle forces, and of physical fitness (aerobic and muscle capacity of lower and upper limbs) on bone mineral content (BMC) and size of total body, lumbar spine, femoral neck, and 1/3 radius in 53 girls and 64 boys from 7.9 to 9.7years of age. After controlling for bone age, body mass, body height, and calcium intake, lean mass was the most important predictor of bone size and/or mineral in both genders (p<0.05), while habitual weight-bearing PA positively influenced BMC in boys (p<0.05). The effect of muscle in bone was not determined by PA and fitness score did not explain bone variability. Femoral neck was the bone site more closely associated with mechanical loading factors; boys with a PA > 608counts/min/day (~105min/day of moderate and vigorous intensity) showed 13-20% more BMC than those with less physical activity, and girls with a lean mass >19kg showed 12-19% more BMC than those with less lean mass. These findings suggest that lean mass was the most important predictor of bone size and/or mineralization in both genders, while habitual weight-bearing PA appears to positively impact on bone mineral in prepubertal boys and that both lean mass and PA need to be considered in physical education curricula and other health-enhancing programs.

Approach to the Child with Fractures

Evaluation of the child with fractures is challenging, as no clear guidelines exist to distinguish traumatic from pathological fractures. Although most fractures in childhood are benign, recurrent fractures may be associated with a wide variety of primary skeletal diseases as well as secondary causes, necessitating a careful history and physical exam to guide the evaluation. There is no "gold standard" for the evaluation and treatment of children with fractures and low bone mineral density (BMD); therefore, the diagnosis of osteoporosis in a pediatric patient should be made using a combination of clinical and radiographic features. Interpretation of bone densitometry in growing patients presents a unique set of challenges because areal BMD measured by dual-energy x-ray absorptiometry depends on multiple dynamic variables. Interpretation of pediatric dual-energy x-ray absorptiometry should be based on Z-scores (sd scores compared to age, sex, and ethnicity-matched controls), using normative databases specific to the brand of densitometer and the patient population. Given the skeleton's ability to recover from low BMD through modeling and remodeling, optimizing management of underlying conditions leading to bone fragility is the initial step. Conservative measures including calcium and vitamin D supplementation and weight-bearing physical activity are important interventions that should not be overlooked. The use of bisphosphonates in children and adolescents is controversial due to lack of long-term efficacy and safety data and should be limited to clinical trials and compassionate therapy in children with significantly compromised quality of life. Close monitoring is required, and further study is necessary to assess their long-term safety and efficacy in children.

Modelling human osteosarcoma in the mouse

Modelling human osteosarcoma in the mouse

Mechanisms underlying the fatal attraction of prostate cancer to bone

Mechanisms underlying the fatal attraction of prostate cancer to bone

Positive Influence of Long-Lasting and Intensive Weight-Bearing Physical Activity on Hip Structure of Young Adults

The aim was to analyze the associations between high-intensity and long-lasting weight-bearing sports with hip structure in young adults. One hundred and seventy-two subjects aged 17–28 yr were divided into 4 groups: 40 athlete women (10.2 ± 2.2 h/wk), 30 control women, 67 athlete men (11.4 ± 3.6 h/wk), and 35 control men. The nondominant femur, lumbar spine, and whole body were scanned by dual-energy X-ray absorptiometry to assess bone mineral content (BMC) and bone mineral density (BMD). Hip structure analysis (HSA) software was applied to evaluate cross-sectional area, cross-sectional moment of inertia, and section modulus at the femoral neck, intertrochanter, and femoral shaft regions. All the BMC and BMD values were significantly higher in athletes of both sexes compared with controls ( p < 0.05). Most of the hip structural parameters were significantly higher ( p < 0.05) in athletes compared with controls. Most of the differences were maintained after adjustments for height, weight, and calcium intake. Positively significant correlations were observed between HSA parameters and physical activity variables in both sexes ( r > 0.32; p < 0.05). Partial correlation suggested that the hours of practice appeared to have a greater influence than the years of practice on hip bone geometry. These results suggest that external mechanical loading is a strong determinant of hip bone structure when weight-bearing physical activity is commenced before puberty and maintained during adulthood.

Development and testing of the BONES physical activity survey for young children

BackgroundWeight-bearing and high intensity physical activities are particularly beneficial for stimulating bone growth in children given that bone responds favorably to mechanical load. While it is important to assess the contribution and impact of weight-bearing physical activity on health outcomes, measurement tools that quantify and provide information on these activities separately from overall physical activity are limited. This study describes the development and evaluation of a pictorial physical activity survey (PAS) that measures children's participation and knowledge of high-intensity, weight-bearing ("bone smart") physical activity.MethodsTo test reliability, two identical sets of the PAS were administered on the same day to 41 children (mean age 7.1 ± 0.8 years; 63% female) and compared. To test validity, accelerometry data from 40 children (mean age 7.7 ± 0.8 years; 50% female) were compared to data provided by the PAS. Agreements between categorical and ordinal items were assessed with Kappa statistics; agreements between continuous indices were assessed with Spearman's correlation tests.ResultsThe subjects produced reliable results in all 10 physical activity participation items (κ range: 0.36-0.73, all p < 0.05), but less reliable in answering if the physical activities were "bone smart" (κ range: -0.04-0.66). Physical activity indices, including metabolic equivalent time and weight-bearing factors, were significant in test-retest analyses (Spearman's r range: 0.57-0.74, all p < 0.001). Minutes of very vigorous activity from the accelerometer were associated with the self-reported weight-bearing activity, moderate-high, and high activity scores from the PAS (Spearman's r range: 0.47-0.48, all p < 0.01). However, accelerometer counts, counts per minute, and minutes of moderate-vigorous and vigorous activity were not associated with the PAS scores.ConclusionsTogether, the results of these studies suggest that the PAS has acceptable test-retest reliability, but limited validity for early elementary school children. This survey demonstrates a first step towards developing a questionnaire that measures high intensity, weight-bearing activity in schoolchildren.

Bone mineral density in childhood cancer survivors (CCS).

9157 Background: Decreased bone mineral density (BMD) has been reported in childhood cancer survivors (CCS). However, factors associated with low BMD in CCS are not well characterized. Objective: To identify factors associated with low BMD (Z-score ≤ −1) in CCS. Methods: In a cross-sectional study of CCS. BMD was determined by dual-energy x-ray absorptiometry. All patients underwent growth hormone (GH) stimulation testing. Multivariable logistic regression was utilized to evaluate relations between anthropometrics, endocrine function, and treatment history with BMD, adjusted for bone age and gender. Results: Of 284 CCS patients, 41 were excluded due to previous diagnosis of GH deficiency (GHD) and/or treatment with GH, leaving 243 subjects (54% males), median age 15.1 years (range 9.5-18.0 years), surviving 5.4-17.8 years after cancer diagnosis. 21% GHD and 0.8% had gonadal failure. 21% had low lumbar spine (L2-L4) BMD and 6% had low total body less head (TBLH) BMD. Brain irradiation (yes vs. no; Odds ratio [OR] 3.8; 95% confidence interval [CI] [1.0, 15.6]), cumulative prednisone equivalent dose (≥ 6350 vs. 0 mg; OR 4.8; CI [1.7, 14.2]), lower lean body mass (LBM) Z-score (per standard deviation (SD); OR 1.8; CI [1.2, 3.0]), and GHD status (yes vs. no; OR 2.8; CI [1.1, 6.7]) were associated with low L2-L4 BMD (adjusted for height, Tanner stage, and age). Lower LBM Z-score (per SD; OR 4.5; CI [1.9, 12.5]) and increased time since diagnosis (>10 vs. 5-10 years; OR 3.8; CI [1.1, 14.3]) were associated with low TBLH BMD (adjusted for height). Conclusions: In CCS, lower LBM, higher cumulative steroid exposure, history of brain irradiation, longer time since diagnosis, and GHD were associated with low BMD. LBM and GHD are the only modifiable risk factors for low BMD. Weight-bearing physical activities and early treatment of GHD to increase BMD are recommended in CCS. No significant financial relationships to disclose.

A Comparison Of Bone Mineral Density Values In Professional Female Handball And Futsal Players And Non-athletes

Attaining peak bone mass during growth period is crucial in reducing the risk of osteoporotic factures later in life. Girls who participate in sports, have been shown to follow a healthier lifestyle and reduce a number of health problems later in life including osteoporosis. In particular, those who perform weight-bearing physical activities attain higher peak bone mass which can result in reduced risk of osteoporotic fractures. PURPOSE: The purpose of this study was to compare bone mineral density of upper body and dominant and non-dominant legs in professional female handball, futsal players, and non-athletes. METHODS: Fifteen handball players (mean ± SD, age: 23.6 ± 3.1 year, height: 169.4 ± 3.6 cm, weight: 62.9 ± 5.7 kg) and 15 futsal players (mean ± SD, age: 24.3 ± 2.8 years, height: 161.1 ± 4.4 cm, weight: 54.3 ± 7 kg) and 15 healthy non-athlete females (mean ± SD; age: 23.8 ± 2 years, height: 160.9 ± 7 cm, weight: 51.5 ± 9.6 kg) were recruited for the study. The physical activity levels and habits of all subjects were recorded and analyzed. Bone mineral density (BMD) was measured by DXA at the lumbar spine and femoral neck, femoral trochanter of dominant and non dominant legs. All subjects completed consent form. This study was approved by University of Isfahan Ethic Committee. RESULTS: BMD value (mg/cm2) of futsal players was significantly greater (P<0.05) than handball players and non athletes in all measurements (lumbar spine 1269 ± 166 mg/cm2 vs. 1154 ± 76.22 vs. 1102 ± 53.5; femoral neck 1161 ± 81.6 vs. 1054 ± 112.6 vs. 874.5 ± 63.2; dominant leg 1126 ± 92.5 vs. 956 ± 85.3 vs. 876 ± 65; non-dominant leg 1196 ± 80 vs. 1012 ± 73.2 vs. 873 ± 62; total (whole body) 1197 ± 83 vs. 1154 ± 76.2 vs. 990 ± 3.3). No significant differences were found between handball players and non athletes (P>0.05). CONCLUSION: This study suggests that the BMDs of all measured sites in futsal players are higher than handball players and non-athlete females. With regard to skills and techniques that are necessary in any kind of sports, some sites of the body get more mechanical stress and subsequently muscles of these sites contract most of the time during activity. This contracted muscle stimulates osteocytes and increases bone mass. Hence, we conclude that several years of playing futsal positively affects bone mineral density.

Relatively High Bone Mineral Density in Chinese Adolescent Dancers Despite Lower Energy Intake and Menstrual Disorder

The effect of dietary restriction, intense exercise and menstrual dysfunction on bone mineral density remains controversial. The aim of this study was to assess the skeletal health status and relationship between bone mineral density and nutrient intake, menstrual status, estrogen level and other factos in Chinese adolescent dancers. Sixty dancers and 77 healthy controls underwent measurements of bone density, body composition, and estrogen level. Nutrient intake, menstrual status and physical activity were assessed with questionnaires. The correlation between these factors were analyzed. The dancers under study had a significantly lean body mass index (18.3 +/- 1.4 kg/m2 vs. 21.7 +/- 3.1 kg/m2), lower percentage of body fat (0.25 +/- 0.05 vs. 0.34 +/- 0.04) and later age at menarche (14.0 +/- 0.9 y vs. 13.0 +/- 1.3 y), and the estrogen level, daily calorie and fat intake in them were also lower than in the controls. All the dancers undertook intensive physical activity every day and up to 69% of them suffered from irregular menarche. Yet they had relatively high BMD and BMC of the total body and legs than the controls after adjusting for BMI and age. Site-specific BMD was positively correlated to BMI, body composition and training hours per week and negatively correlated to the age at menarche and menstrual frequency. The relatively high BMD and BMC of the dancers at the total body and legs were probably caused by high levels of weight-bearing physical activity. To ameliorate disordered eating, especially low energy intake might be helpful to prevent the Triad and to improve the bone health in adolescent dancers.

The differences in bone mineral content between female dancers and controls aged 15 - 17 years old and its relationship with physical activity level

To assess bone mineral content (BMC) of 15 - 17 year-old dancers and high school females and analyze the relationship between physical activity status and BMC. Sixty dancers and 77 healthy controls aged 15 - 17 years old were enrolled in our study. BMC in the total body and forearm were measured by dual-energy X-ray absorptiometry (DEXA) while body weight and height were also measured. Physical activity information was collected by "one-year physical activity questionnaire". The physical activity level (PAL) and the average daily energy expenditure (EE) of dancers were all higher than controls (PAL: 2.17 +/- 0.34 vs 1.63 +/- 0.34, t = 7.283; EE: (6876.43 +/- 1036.72) kJ vs (5388.43 +/- 920.83) kJ, t = 7.214, both P values < 0.01). The dancers showed lower BMC/height at total body and arms compared with the controls (the total body BMC/height was (13.896 +/- 1.308) vs (14.494 +/- 1.272) g/cm, F = -2.563); and the BMC/height of left and right arm were (0.779 +/- 0.088) vs (0.829 +/- 0.101) g/cm (F = -2.892) and (0.766 +/- 0.093) vs (0.829 +/- 0.097) g/cm (F = -3.650) respectively, all these P values were < 0.01.Yet after adjusting age and BMI, the dancers showed higher BMC/height at total body and legs, the corresponding values were (14.550 +/- 0.146) vs (13.947 +/- 0.131) g/cm (F = 7.868), (2.681 +/- 0.033) vs (2.389 +/- 0.030) g/cm (F = 36.520), (2.821 +/- 0.031) vs (2.450 +/- 0.028) g/cm (F = 65.279), all these P values were < 0.01. While no differences were found with controls at non-weight bearing sites (arms). Daily period (h) of training was significantly related to BMC/height of legs, total body (r value were 0.618, 0.448 and 0.554 respectively, all the P values < 0.01), while the history of training was also correlated with BMC/height of two legs (r value were 0.38 and 0.304 respectively, both P values < 0.05). The adolescent dancers showed higher BMC after adjusting age and BMI, which was attributed to the long-term high level weight-bearing physical activity.

The link between physical activity and bone strength across the lifespan

Weight-bearing physical activity plays an important role in bone health across the lifespan. During childhood, short bouts of high-impact activity augment bone-mass accrual and enhance bone's structural characteristics that contribute to overall bone strength. Along the age continuum, physical activity in adulthood serves to maintain bone mass and strength and in later life, to diminish bone loss. While the specific exercise prescription for bone strength in women and men is not known, a combination of resistance training and impact exercise may offer the best strategy to promote bone health in older adults and ultimately, reduce fracture risk. In this review we discuss the central role that physical activity plays in promoting bone health across the lifespan. Specifically, we focus on the adaptations in bone structure and strength to weight-bearing physical activity.

Longitudinal effect of vigorous physical activity on patella cartilage morphology in people without clinical knee disease

There are few data concerning possible long-term effects of physical activity on cartilage change in the patellofemoral compartment. We examined the effect of participation in vigorous physical activity on changes to patella cartilage over 2 years. A total of 297 healthy adults ages 50-79 years with no history of knee injury or symptoms were recruited from an existing study. Physical activity data were obtained by questionnaire at baseline (2003-2004). Patella cartilage volume and defects were determined by magnetic resonance imaging at baseline (2003-2004) and followup (2006-2007). Participation in vigorous physical activity at baseline was associated with a reduced rate of patella cartilage volume loss (-21.2 mm(3) per annum [95% confidence interval (95% CI) -41.5, -1.0; P = 0.04]) and a trend toward less risk of worsening patella cartilage defects (odds ratio 0.4; 95% CI 0.2, 1.1 [P = 0.07]) over the subsequent 2 years. In the subgroup with no significant patella cartilage defects at baseline (n = 192), participation in vigorous physical activity was associated with a reduced annual rate of patella cartilage volume loss (95% CI -53.8, -7.8; P = 0.03) and a trend for fewer new patella cartilage defects (95% CI 0.1, 1.1; P = 0.08). No significant relationships were found between vigorous physical activity and cartilage volume change or defect progression in the subgroup with prevalent patella cartilage defects at baseline. These observations suggest that vigorous physical activity is beneficial to patellofemoral joints for people without preexisting cartilage damage. Weight-bearing vigorous physical activity might, therefore, be useful in the prevention of patellofemoral osteoarthritis.