The effects of exercise and physical activity participation on bone mass and geometry in postmenopausal women: a systematic review of pQCT studies

Bone quality: the determinants of bone strength and fragility

Bone fragility is a major health concern, as the increased risk of bone fractures has devastating outcomes in terms of mortality, decreased autonomy, and healthcare costs. Efforts made to address this problem have considerably increased our knowledge about the mechanisms that regulate bone formation and resorption. In particular, we now have a much better understanding of the cellular events that are triggered when bones are mechanically stimulated and how these events can lead to improvements in bone mass. Despite these findings at the molecular level, most exercise intervention studies reveal either no effects or only minor benefits of exercise programs in improving bone mineral density (BMD) in osteoporotic patients. Nevertheless, and despite that BMD is the gold standard for diagnosing osteoporosis, this measure is only able to provide insights regarding the quantity of bone tissue. In this article, we review the complex structure of bone tissue and highlight the concept that its mechanical strength stems from the interaction of several different features. We revisited the available data showing that bone mineralization degree, hydroxyapatite crystal size and heterogeneity, collagen properties, osteocyte density, trabecular and cortical microarchitecture, as well as whole bone geometry, are determinants of bone strength and that each one of these properties may independently contribute to the increased or decreased risk of fracture, even without meaningful changes in aBMD. Based on these findings, we emphasize that while osteoporosis (almost) always causes bone fragility, bone fragility is not always caused just by osteoporosis, as other important variables also play a major role in this etiology. Furthermore, the results of several studies showing compelling data that physical exercise has the potential to improve bone quality and to decrease fracture risk by influencing each one of these determinants are also reviewed. These findings have meaningful clinical repercussions as they emphasize the fact that, even without leading to improvements in BMD, exercise interventions in patients with osteoporosis may be beneficial by improving other determinants of bone strength.

Impact of lifestyle factors on fracture risk in older patients with cardiovascular disease: a prospective cohort study of 26,335 individuals from 40 countries

BACKGROUND

fractures are a major health concern among the elderly. People at risk for cardiovascular disease (CVD) are at an increased risk for fractures. The aim of this study was to assess the individual and combined effect of the CVD risk factors of smoking, alcohol consumption and physical activity on fracture risk in a large sample of older individuals with CVD or diabetes with end-organ damage.

METHODS

we analysed data for 26,335 adults, aged 55 years or older, who participated in two large antihypertensive drug treatment trials and who had no previous fracture at baseline. Lifestyle factors were assessed by the standardised questionnaire and their individual and combined effects on incident fracture risk were modelled using Cox proportional hazard regression.

RESULTS

during the 56-month follow-up, 1,079 incident fractures occurred; 508 (6.51%) among women and 571 (3.08%) among men. Smoking [hazard ratio (HR) 1.52, 95% confidence interval (CI) 1.27-1.82] and low physical activity (HR: 1.19, 95% CI: 1.05-1.36) were associated with an increased risk of any fracture, while high alcohol intake showed a directional, but non-significant, relationship with fracture risk (HR: 1.09, 95% CI: 0.64-1.84). Compared with participants with no lifestyle risk factors, those having one, two, or three risk factors had an increased risk of a future fracture (HR: 1.17, 95% CI: 1.03-1.34 for one risk factor; HR: 1.73, 95% CI: 1.38-2.16 for two risk factors; and HR: 2.37, 95% CI: 0.88-6.36 for three risk factors; P for trend <0.001).

CONCLUSIONS

a healthier lifestyle advocated to reduce the risk of CVD is associated with a significant and graded reduction in fracture risk.

Skeletal muscle as a regulator of the longevity protein, Klotho

Klotho is a powerful longevity protein that has been linked to the prevention of muscle atrophy, osteopenia, and cardiovascular disease. Similar anti-aging effects have also been ascribed to exercise and physical activity. While an association between muscle function and Klotho expression has been previously suggested from longitudinal cohort studies, a direct relationship between circulating Klotho and skeletal muscle has not been investigated. In this paper, we present a review of the literature and preliminary evidence that, together, suggests Klotho expression may be modulated by skeletal muscle activity. Our pilot clinical findings performed in young and aged individuals suggest that circulating Klotho levels are upregulated in response to an acute exercise bout, but that the response may be dependent on fitness level. A similar upregulation of circulating Klotho is also observed in response to an acute exercise in young and old mice, suggesting that this may be a good model for mechanistically probing the role of physical activity on Klotho expression. Finally, we highlight overlapping signaling pathways that are modulated by both Klotho and skeletal muscle and propose potential mechanisms for cross-talk between the two. It is hoped that this review will stimulate further consideration of the relationship between skeletal muscle activity and Klotho expression, potentially leading to important insights into the well-documented systemic anti-aging effects of exercise.

Modern rehabilitation in osteoporosis, falls, and fractures

In prevention and management of osteoporosis, modern rehabilitation should focus on how to increase muscular and bone strength. Resistance exercises are beneficial for muscle and bone strength, and weight-bearing exercises help maintain fitness and bone mass. In subjects at higher risk for osteoporotic fractures, particular attention should be paid to improving balance – the most important element in falls prevention. Given the close interaction between osteoporosis and falls, prevention of fractures should be based on factors related to bone strength and risk factors for falls. Fractures are the most serious complication of osteoporosis and may be prevented. The use of modern spinal orthosis helps to reduce pain and improve posture. Vibration platforms are used in rehabilitation of osteoporosis, based on the concept that noninvasive, short-duration, mechanical stimulation could have an impact on osteoporosis risk. Pharmacologic therapy should be added for those at high risk of fracture, and vitamin D/calcium supplementation is essential in all prevention strategies. Success of rehabilitation in osteoporotic and fractured subjects through an individualized educational approach optimizes function to the highest level of independence while improving the overall quality of life.

Milk consumption during teenage years and risk of hip fractures in older adults

IMPORTANCE

Milk consumption during adolescence is recommended to promote peak bone mass and thereby reduce fracture risk in later life. However, its role in hip fracture prevention is not established and high consumption may adversely influence risk by increasing height.

OBJECTIVES

To determine whether milk consumption during teenage years influences risk of hip fracture in older adults and to investigate the role of attained height in this association.

DESIGN, SETTING, AND PARTICIPANTS

Prospective cohort study over 22 years of follow-up in more than 96,000 white postmenopausal women from the Nurses' Health Study and men aged 50 years and older from the Health Professionals Follow-up Study in the United States.

EXPOSURES

Frequency of consumption of milk and other foods during ages 13 to 18 years and attained height were reported at baseline. Current diet, weight, smoking, physical activity, medication use, and other risk factors for hip fractures were reported on biennial questionnaires.

MAIN OUTCOMES AND MEASURES

Cox proportional hazards models were used to calculate relative risks (RRs) of first incidence of hip fracture from low-trauma events per glass (8 fl oz or 240 mL) of milk consumed per day during teenage years.

RESULTS

During follow-up, 1226 hip fractures were identified in women and 490 in men. After controlling for known risk factors and current milk consumption, each additional glass of milk per day during teenage years was associated with a significant 9% higher risk of hip fracture in men (RR = 1.09; 95% CI, 1.01-1.17). The association was attenuated when height was added to the model (RR = 1.06; 95% CI, 0.98-1.14). Teenage milk consumption was not associated with hip fractures in women (RR = 1.00 per glass per day; 95% CI, 0.95-1.05).

CONCLUSIONS AND RELEVANCE

Greater milk consumption during teenage years was not associated with a lower risk of hip fracture in older adults. The positive association observed in men was partially mediated through attained height.

Muscle size, strength, and physical performance and their associations with bone structure in the Hertfordshire Cohort Study

Sarcopenia is associated with a greater fracture risk. This relationship was originally thought to be explained by an increased risk of falls in sarcopenic individuals. However, in addition, there is growing evidence of a functional muscle-bone unit in which bone health may be directly influenced by muscle function. Because a definition of sarcopenia encompasses muscle size, strength, and physical performance, we investigated relationships for each of these with bone size, bone density, and bone strength to interrogate these hypotheses further in participants from the Hertfordshire Cohort Study. A total of 313 men and 318 women underwent baseline assessment of health and detailed anthropometric measurements. Muscle strength was measured by grip strength, and physical performance was determined by gait speed. Peripheral quantitative computed tomography (pQCT) examination of the calf and forearm was performed to assess muscle cross-sectional area (mCSA) at the 66% level and bone structure (radius 4% and 66% levels; tibia 4% and 38% levels). Muscle size was positively associated with bone size (distal radius total bone area β = 17.5 mm2 /SD [12.0, 22.9]) and strength (strength strain index (β = 23.3 mm3 /SD [18.2, 28.4]) amongst women (p < 0.001). These associations were also seen in men and were maintained after adjustment for age, height, weight-adjusted-for-height, limb-length-adjusted-for-height, social class, smoking status, alcohol consumption, calcium intake, physical activity, diabetes mellitus, and in women, years since menopause and estrogen replacement therapy. Although grip strength showed similar associations with bone size and strength in both sexes, these were substantially attenuated after similar adjustment. Consistent relationships between gait speed and bone structure were not seen. We conclude that although muscle size and grip strength are associated with bone size and strength, relationships between gait speed and bone structure and strength were not apparent in this cohort, supporting a role for the muscle-bone unit.

The Relationship between Radial Bone Properties and Disease Activity and Physical Function in Individuals with Rheumatoid Arthritis

PURPOSE

People with rheumatoid arthritis (RA) are at increased risk for osteoporosis. This study explored the relationships between compartment-specific (cortical and trabecular) bone properties in the distal radius, a common site for osteoporotic fracture, and RA-related pain, upper-limb disease activity, and hand function in adults diagnosed within the previous 8 years.

METHODS

Cortical and trabecular bone properties (mass, density, and apparent trabecular structure) were assessed at the 4% site of the radius in 21 adults with RA using peripheral quantitative computed tomography (pQCT). Clinical measures included upper-limb active joint count; self-reported pain (AIMS-2 Arthritis Pain scale) and physical function (AIMS-2 Hand and Finger Function scale); and grip strength (modified sphygmomanometer). Associations were characterized using correlations (Pearson correlation coefficients or Spearman's rho).

RESULTS

Cortical and trabecular bone mass and trabecular bone density were negatively associated with the number of active joints (r=-0.47, -0.54, and -0.47, respectively). Cortical bone density and mass were associated with grip strength (r=0.61 and 0.51, respectively). Cortical and trabecular bone density and cortical bone mass were negatively associated with scores on the Hand and Finger Function scale (r=-0.49, -0.45 and -0.56, respectively).

CONCLUSIONS

Although the patterns differed slightly for cortical and trabecular bone, better bone health in both compartments was associated with fewer active joints and lower self-reported hand disability in adults with RA.

Site-specific variance in radius and tibia bone strength as determined by muscle size and body mass

PURPOSE

To investigate the predictive ability of muscle cross-sectional area (MCSA) and body mass on bone mineral content, compressive bone strength index (BSIc), and the polar stress-strain index (SSIp) of the forearms and lower legs of middle-aged adults.

METHODS

A total of 53 healthy adults (37 male, 16 female; mean age 50.4; SD 2.1 y) were scanned with peripheral quantitative computed tomography (pQCT) to measure radius and tibia total and cortical bone mineral content, BSIc, SSIp, and forearm and lower-leg MCSA (BSIc: 4% distal; SSIp and MCSA at 65% and 66% radius and tibia shaft sites, respectively). Multiple regression models adjusted for sex and height were used to assess the relative variance in radius or tibia bone outcomes predicted by body mass and/or forearm or lower-leg MCSA.

RESULTS

Forearm MCSA independently predicted total bone-mineral content, BSIc, and SSIp in radius (r partial=0.59, 0.56, 0.42). Body mass was a negative predictor of radius BSIc (r partial=-0.32) and did not predict other radius outcomes when both body mass and MCSA were forced in the models. In the lower leg shaft, MCSA, and body mass predicted bone content and strength similarly when independently added to the models with sex and height.

CONCLUSIONS

Forearm MCSA was a dominant predictor of radius bone content and estimated strength. In the tibia, both body mass and lower-leg MCSA contributed to predicting bone content and estimated strength.

Bone geometry according to menstrual function in female endurance athletes

Athletes have higher bone mineral density (BMD) relative to nonathletes. In amenorrheic athletes BMD may be compromised by estrogen deficiency, but it is unknown whether this is accompanied by structural differences. We compared femoral neck bone geometry and density of a-/oligomenorrheic athletes (AAs), eumenorrheic athletes (EAs), and eumenorrheic controls (ECs). We recruited 156 women: (68 endurance athletes and 88 controls). Femoral neck BMD, section modulus (Z), and width were measured using dual-energy X-ray absorptiometry. Menstrual function was assessed by questionnaire and classified as EA (≥10 periods/year) or AA (≤9 periods/year): 24 athletes were AA and 44 EA. Femoral neck BMD was significantly higher in EA than AA (8 %, difference) and EC (11 % difference): mean [SE] 1.118 [0.015], 1.023 [0.020] and 0.999 [0.014] g cm(-2), respectively; p < 0.001. Z was significantly higher in EA than EC (11 % difference): EA 667 [19], AA 625 [21], and EC 592 [10] cm(3); p < 0.001. Femoral neck width did not differ between groups. All differences persisted after adjustment for height, age, and body mass. The higher femoral neck Z and BMD in athletes, despite similar width, may indicate that exercise-related bone gains are endosteal rather than periosteal. Athletes with amenorrhea had smaller increments in bone mass rather than structural adaptation. The maintained femoral neck width in controls may be an adaptive mechanism to conserve bone strength in bending despite inactivity-related bone decrement.

High impact exercise increased femoral neck bone mineral density in older men: a randomised unilateral intervention

INTRODUCTION

There is little evidence as to whether exercise can increase BMD in older men with no investigation of high impact exercise. Lifestyle changes and individual variability may confound exercise trials but can be minimised using a within-subject unilateral design (exercise leg [EL] vs. control leg [CL]) that has high statistical power.

PURPOSE

This study investigated the influence of a 12month high impact unilateral exercise intervention on femoral neck BMD in older men.

METHODS

Fifty, healthy, community-dwelling older men commenced a 12month high impact unilateral exercise intervention which increased to 50 multidirectional hops, 7days a week on one randomly allocated leg. BMD of both femurs was measured using dual energy X-ray absorptiometry (DXA) before and after 12months of exercise, by an observer blind to the leg allocation. Repeated measures ANOVA with post hoc tests was used to detect significant effects of time, leg and interaction.

RESULTS

Thirty-five men (mean±SD, age 69.9±4.0years) exercised for 12months and intervention adherence was 90.5±9.1% (304±31 sessions completed out of 336 prescribed sessions). Fourteen men did not complete the 12month exercise intervention due to: health problems or injuries unrelated to the intervention (n=9), time commitments (n=2), or discomfort during exercise (n=3), whilst BMD data were missing for one man. Femoral neck BMD, BMC and cross-sectional area all increased in the EL (+0.7, +0.9 and +1.2 % respectively) compared to the CL (-0.9, -0.4 and -1.2%); interaction effect P<0.05. Although the interaction term was not significant (P>0.05), there were significant main effects of time for section modulus (P=0.044) and minimum neck width (P=0.006). Section modulus increased significantly in the EL (P=0.016) but not in the CL (P=0.465); mean change +2.3% and +0.7% respectively, whereas minimum neck width increased significantly in the CL (P=0.004) but not in the EL (P=0.166); mean changes being +0.7% and +0.3% respectively.

CONCLUSION

A 12month high impact unilateral exercise intervention was feasible and effective for improving femoral neck BMD, BMC and geometry in older men. Carefully targeted high impact exercises may be suitable for incorporation into exercise interventions aimed at preventing fractures in healthy community-dwelling older men.

Lifestyle factors and site-specific risk of hip fracture in community dwelling older women--a 13-year prospective population-based cohort study

BACKGROUND

Several risk factors are associated to hip fractures. It seems that different hip fracture types have different etiologies. In this study, we evaluated the lifestyle-related risk factors for cervical and trochanteric hip fractures in older women over a 13-year follow-up period.

METHODS

The study design was a prospective, population-based study consisting of 1681 women (mean age 72 years). Seventy-three percent (n = 1222) participated in the baseline measurements, including medical history, leisure-time physical activity, smoking, and nutrition, along with body anthropometrics and functional mobility. Cox regression was used to identify the independent predictors of cervical and trochanteric hip fractures.

RESULTS

During the follow-up, 49 cervical and 31 trochanteric fractures were recorded. The women with hip fractures were older, taller, and thinner than the women with no fractures (p < 0.05). Low functional mobility was an independent predictor of both cervical and trochanteric fractures (HR = 3.4, 95% CI 1.8-6.6, and HR = 5.3, 95% CI 2.5-11.4, respectively). Low baseline physical activity was associated with an increased risk of hip fracture, especially in the cervical region (HR = 2.5, 95% CI 1.3-4.9). A decrease in cervical fracture risk (p = 0.002) was observed with physically active individuals compared to their less active peers (categories: very low or low, moderate, and high). Moderate coffee consumption and hypertension decreased the risk of cervical fractures (HR = 0.4, 95% CI 0.2-0.8, for both), while smoking was a predisposing factor for trochanteric fractures (HR = 3.2, 95% CI 1.1-9.3).

CONCLUSIONS

Impaired functional mobility, physical inactivity, and low body mass may increase the risk for hip fractures with different effects at the cervical and trochanteric levels.

Review article: non-alcoholic fatty liver disease and osteoporosis--clinical and molecular crosstalk

BACKGROUND

Low bone mineral density (BMD) has been reported in both paediatric and adult patients with non-alcoholic fatty liver disease (NAFLD). The mechanisms behind the reduced BMD in NAFLD are still not completely understood.

AIM

To provide a critical overview of the pathophysiological pathways linking NAFLD, reduced BMD and osteoporosis, with a special focus on the alterations of soluble mediators which could link fat accumulation in the liver with bone health. The MEDLINE database was searched by a combination of keywords: non-alcoholic fatty liver disease OR hepatic steatosis OR metabolic syndrome OR insulin resistance AND bone mineral density OR osteoporosis OR bone AND biomarkers OR serum marker.

RESULTS

Several factors that may influence bone mineralisation and the increased risk of osteoporosis in NAFLD can be discussed. These include the release of cytokines from the inflamed liver which may influence the bone microenvironment, vitamin D deficiency, and limited physical activity. Circulating markers of bone metabolism, including osteopontin, osteoprotegerin, osteocalcin and fetuin-A, have been found to be altered in patients with NAFLD.

CONCLUSION

A better understanding of the mechanisms that link bone metabolism and the liver may open a new frontier to fight two highly prevalent conditions like NAFLD and osteoporosis.

Effects of training on bone mass in older adults: a systematic review

It is widely recognized that the risk of fractures is closely related to the typical decline in bone mass during the ageing process in both women and men. Exercise has been reported as one of the best non-pharmacological ways to improve bone mass throughout life. However, not all exercise regimens have the same positive effects on bone mass, and the studies that have evaluated the role of exercise programmes on bone-related variables in elderly people have obtained inconclusive results. This systematic review aims to summarize and update present knowledge about the effects of different types of training programmes on bone mass in older adults and elderly people as a starting point for developing future interventions that maintain a healthy bone mass and higher quality of life in people throughout their lifetime. A literature search using MEDLINE and the Cochrane Central Register of Controlled Trials databases was conducted and bibliographies for studies discussing the effect of exercise interventions in older adults published up to August 2011 were examined. Inclusion criteria were met by 59 controlled trials, 7 meta-analyses and 8 reviews. The studies included in this review indicate that bone-related variables can be increased, or at least the common decline in bone mass during ageing attenuated, through following specific training programmes. Walking provides a modest increase in the loads on the skeleton above gravity and, therefore, this type of exercise has proved to be less effective in osteoporosis prevention. Strength exercise seems to be a powerful stimulus to improve and maintain bone mass during the ageing process. Multi-component exercise programmes of strength, aerobic, high impact and/or weight-bearing training, as well as whole-body vibration (WBV) alone or in combination with exercise, may help to increase or at least prevent decline in bone mass with ageing, especially in postmenopausal women. This review provides, therefore, an overview of intervention studies involving training and bone measurements among older adults, especially postmenopausal women. Some novelties are that WBV training is a promising alternative to prevent bone fractures and osteoporosis. Because this type of exercise under prescription is potentially safe, it may be considered as a low impact alternative to current methods combating bone deterioration. In other respects, the ability of peripheral quantitative computed tomography (pQCT) to assess bone strength and geometric properties may prove advantageous in evaluating the effects of training on bone health. As a result of changes in bone mass becoming evident by pQCT even when dual energy X-ray absortiometry (DXA) measurements were unremarkable, pQCT may provide new knowledge about the effects of exercise on bone that could not be elucidated by DXA. Future research is recommended including longest-term exercise training programmes, the addition of pQCT measurements to DXA scanners and more trials among men, including older participants.

[Impact of physical activity and exercise on bone health in the life course : a review]

Physical activity and exercise are important determinants for metabolic and cardiovascular health. They also play an important role for bone health in childhood, adolescence, and adulthood. This review summarizes results from observational and intervention studies which evaluated the association between physical activity/exercise and bone health in different life course stages. In childhood and adolescence, physical activity and exercise induce improved bone accrual. In adulthood, mainly in postmenopausal women, long-term exercise programs reduce age-related bone loss. Especially weight-bearing activities seem to have an important osteogenic effect. Children and adolescent show a higher bone accrual until 5 years after cessation of an exercise program compared to their peers, who do not participate in an exercise program. In contrast, adults who quit exercising have a higher decrease in bone stiffness compared to adults who never exercised. This effect was particularly seen in postmenopausal women. Continuous physical activity and exercise over the life course and the implementation of exercise programs in schools and community-based intervention programs can help prevent or even reduce osteoporosis and osteoporosis-related fractures. Due to the lack of prospective longitudinal studies, the supposed long-term sustainable protective effect of physical activity and exercise in childhood and adolescent on bone health in later adulthood is not well established.

Imaging-Based Methods for Non-invasive Assessment of Bone Properties Influenced by Mechanical Loading

PURPOSE

To describe the most common in vivo imaging-based research tools used to assess bone properties that are influenced by mechanical loading associated with exercise, habitual physical activity, or disease states. Bone is a complex metabolically active tissue that adapts to changes in mechanical loading by altering the amount and spatial organization of mineral.

METHOD

Using a narrative review design, the authors provide an overview of bone biology and biomechanics to emphasize the importance of bone size scale, porosity, and degree of mineralization when interpreting measures acquired using quantitative ultrasound (QUS), dual-energy X-ray absorptiometry (DXA), computed tomography (CT), magnetic resonance imaging (MRI), and finite element analysis (FEA). For each imaging modality, basic imaging principles, typical outcome measures associated with changes in mechanical loading, and salient features for physiotherapists are described.

MAIN RESULTS

While each imaging modality has strengths and limitations, currently CT-based methods are best suited for determining the effects of mechanical loading on bone properties-particularly in the peripheral skeleton.

CONCLUSIONS

Regardless of the imaging technology used, the physiotherapist must carefully consider the assumptions of the imaging-based method, the clinical context, the nature of the change in mechanical loading, and the expected time course for change in bone properties.

Purpose: To describe the most common in vivo imaging-based research tools used to assess bone properties that are influenced by mechanical loading associated with exercise, habitual physical activity, or disease states. Bone is a complex metabolically active tissue that adapts to changes in mechanical loading by altering the amount and spatial organization of mineral. Method: Using a narrative review design, the authors provide an overview of bone biology and biomechanics to emphasize the importance of bone size scale, porosity, and degree of mineralization when interpreting measures acquired using quantitative ultrasound (QUS), dual-energy X-ray absorptiometry (DXA), computed tomography (CT), magnetic resonance imaging (MRI), and finite element analysis (FEA). For each imaging modality, basic imaging principles, typical outcome measures associated with changes in mechanical loading, and salient features for physiotherapists are described. Main Results: While each imaging modality has strengths and limitations, currently CT-based methods are best suited for determining the effects of mechanical loading on bone properties—particularly in the peripheral skeleton. Conclusions: Regardless of the imaging technology used, the physiotherapist must carefully consider the assumptions of the imaging-based method, the clinical context, the nature of the change in mechanical loading, and the expected time course for change in bone properties.

Exercise effects on hip bone mineral density in older, post-menopausal breast cancer survivors are age dependent

We evaluated whether age moderated the effect of impact + resistance exercise on hip BMD in older post-menopausal breast cancer survivors (BCS). Exercise was more beneficial among younger than older women within our sample, suggesting that much older BCS may require different training programs to improve hip health.

PURPOSE

Previously, we reported that a program of resistance + impact training stopped bone loss at the spine in older, post-menopausal BCS but had no effect on bone mineral density (BMD) at the hip. Aging may blunt the responsiveness of the hip to mechanical loading, so we conducted a secondary data analysis to evaluate whether age moderated the effect of exercise on hip BMD.

METHODS

We analyzed data from our randomized, controlled trial in older (≥ 50 years of age at diagnosis), post-menopausal, post-adjuvant treatment BCS (n = 106) comparing women assigned to impact + resistance exercise (POWIR) or to a control program of low-intensity stretching (FLEX). We examined effect modification by age on BMD at three hip sites (greater trochanter, femoral neck, and total hip) using hierarchical linear modeling adjusting for time since diagnosis and use of adjuvant hormone therapy.

RESULTS

Age moderated the effect of exercise on total hip BMD such that younger women in POWIR were more likely to see a positive net benefit than FLEX compared to older women where there was little difference between groups (p = 0.02).

CONCLUSIONS

The skeletal response to loading at the hip within post-menopausal BCS diminishes with age. Whether more vigorous exercise programs and/or longer training periods are required to favorably change hip health in older BCS will require future study and careful thought about the risks and benefits of tougher training programs.

The relationship between accelerometer-determined physical activity (PA) and body composition and bone mineral density (BMD) in postmenopausal women

Studies of the relationships between BMD, PA and body composition have shown variable results. Therefore, the aim of this cross-sectional study was to determine the relationships between accelerometer-determined PA and selected body composition parameters to total and regional BMD of the proximal femur in postmenopausal women. BMD and body composition were measured using dual energy X-ray absorptiometry in 97 women with a mean age 63.63±5.23 years. PA was monitored using an ActiGraph GT1M accelerometer. Correlation analysis did not show significant relationships between PA variables and BMD, but increases in body composition variables were associated with increases in BMD. Lean body mass was the strongest predictor of proximal femur BMD (r=0.18-0.37), explaining 10% of the variance for total femur, and 3-14% of the variance for regional femurs. Correlations increased when the analysis was controlled for age (r(p)=0.20-0.39). A significant relationship was also found between body fat mass and BMD (r=0.16-0.30; r(p)=0.25-0.37). Analysis of differences between women with normal BMD and osteopenic women showed statistically significant differences in age (p=0.003; η(2)=0.09) and lean body mass (p=0.048; η(2)=0.04). In conclusion, body composition is a stronger predictor of proximal femur BMD than PA variables. However, other studies are necessary to clarify the influence of long-term PA and exercise type on proximal femur BMD.

Osteoporosis update

INTRODUCTION

Osteoporosis is a chronic disease that is estimated to affect more than 75 million people worldwide. The US Department of Health and Human Services projects that the disease will impact more than 10 million women by 2020 if efforts to prevent it are ineffective. This article provides an overview of the pathophysiology of osteoporosis, prevention measures, and an update of the US Food and Drug Administration-approved medications that are used in the treatment of this widespread disease.

METHODS

The current literature on the pathology, risks, and treatment of osteoporosis was reviewed. Studies providing the evidence for best practices are included in the following sections: prevention, diagnosis, and treatment of osteoporosis. Current national standards for diagnosis and treatment are highlighted.

RESULTS

Bisphosphonates continue to be the most popular and widely used pharmacologic treatment for osteoporosis. However, when bisphosphonates are contraindicated or cause side effects so serious that it is not possible for some women to use them, alternative pharmacologic treatments and forms of dosing are available.

DISCUSSION

When lifestyle and dietary modifications are insufficient to offset a diagnosis of osteoporosis, there are a variety of pharmaceutical options available that will provide safe and effective protection against fracture due to osteoporosis.

The effect of exercise on pQCT parameters of bone structure and strength in postmenopausal women--a systematic review and meta-analysis of randomized controlled trials

Inconsistent study findings of exercise on areal bone density highlight the need to include parameters of bone geometry and volumetric bone density measurements. Using a systematic review and meta-analysis, we found a decrease in bone loss through the maintenance of cortical and trabecular volumetric bone mineral density (BMD). Studies with longer exercise durations and larger sample sizes are needed.

INTRODUCTION

Exercise has long been recommended to prevent age-related loss of bone mass in postmenopausal women. However, inconsistent study findings on the effect of exercise on BMD preservation have highlighted the importance of extending the evaluation of bone to include the parameters of bone geometry. We conducted both a systematic review and meta-analysis of the effects of exercise on bone geometry and volumetric BMD in postmenopausal women.

METHODS

We searched MEDLINE, PubMed, and EMBASE from 1950 to April 2009 and included prospective, randomized controlled trials of healthy postmenopausal women where the intervention involved exercise or sport and outcomes included quantitative or peripheral quantitative computed tomography bone parameters. Outcome variables included: total volumetric BMD, cortical volumetric BMD (CvBMD), trabecular volumetric BMD (TrvBMD), total bone mineral content, cortical BMC, total bone area, cortical area, polar stress-strain index, and bone strength index.

RESULTS

Six studies satisfied our inclusion and exclusion criteria. Lower extremity exercises resulted in small (∼0.9%) but significant improvements in TrvBMD of the distal tibia (p = 0.0006) and in CvBMD of the tibial shaft (p = 0.0007). Studies with longer durations of exercise (12 months) and those in early postmenopausal women showed significant changes in CvBMD at the tibial shaft.

CONCLUSIONS

We conclude that exercise in postmenopausal women may decrease bone loss by maintaining cortical and trabecular volumetric BMD. To better understand the effect of exercise on bone geometric structure and strength, more studies of longer duration and larger sample sizes are needed.

Fracture risk and prevention: a multidimensional approach

Although physical therapists commonly manage neuromusculoskeletal disorders and injuries, their scope of practice also includes prevention and wellness. In particular, this perspective article proposes that physical therapists are well positioned to address the client's skeletal health by incorporating fracture prevention into clinical practice with all adults. Fracture prevention consists primarily of maximizing bone strength and preventing falls. Both of these initiatives require an evidence-based, multidimensional approach that customizes interventions based on an individual's medical history, risk factors, and personal goals. The purposes of this perspective article are: (1) to review the role of exercise and nutrition in bone health and disease; (2) to introduce the use of the Fracture Risk Assessment Tool (FRAX®) into physical therapist practice; (3) to review the causes and prevention of falls; and (4) to propose a role for the physical therapist in promotion of bone health for all adult clients, ideally to help prevent fractures and their potentially devastating sequelae.

[Is there a place for the physical activity in the prevention of the fractures of chronic kidney disease patients?]

The risk of non-traumatic fractures is greatly increased in kidney disease patients and well demonstrated in dialysis patients. If osteoporosis plays a major role in the general population, in chronic kidney disease renal osteodystrophy is associated with neurological and muscular disorders, which probably worsen the risk. The decrease in physical activity is a factor contributing to the loss of bone mass and the initiation of a rehabilitation program improves the prognosis. Despite the association between chronic renal disease and sedentary lifestyle, the relationship between physical inactivity and bones in dialysis patients and the effect of increased activity programs, are not well documented in the literature.

Exercise protects bone after stroke, or does it? A narrative review of the evidence

Physical inactivity contributes to accelerated bone loss after stroke, leading to heightened fracture risk, increased mortality, and reduced independence. This paper sought to summarise the evidence for the use of physical activity to protect bone in healthy adults and adults with stroke, and to identify international recommendations regarding any means of bone protection after stroke, in order to guide rehabilitation practice and future research. A search was undertaken, which identified 12 systematic reviews of controlled trials which investigated the effect of physical activity on bone outcomes in adults. Nine reviews included healthy adults and three included adults with stroke. Twenty-five current international stroke management guidelines were identified. High-impact loading exercise appears to have a site-specific effect on the microarchitecture of healthy postmenopausal women, and physical activity has a small effect on enhancing or maintaining bone mineral density in chronic stroke patients. It is not known whether this translates to reduce fracture risk. Most guidelines included recommendations for early mobilisation after stroke and falls prevention. Two recommendations were identified which advocated exercise for the prevention bone loss after stroke, but supporting evidence was limited. Research is required to determine whether targeted physical activity can protect bone from early after stroke, and whether this can reduce fracture risk.

Stepping towards prevention of bone loss after stroke: a systematic review of the skeletal effects of physical activity after stroke

Bone loss after stroke is pronounced, and contributes to increased fracture risk. People who fracture after stroke experience reduced mobility and increased mortality. Physical activity can maintain or improve bone mineral density and structure in healthy older adults, likely reducing fracture risk. The purpose of this systematic review was to investigate the skeletal effects of physical activity in adults affected by stroke. A search of electronic databases was undertaken. Selection criteria of trials were • prospective and controlled • physical activity-based intervention • participants with history of stroke, and • bone-related outcome measures. Effect sizes were calculated for outcomes of paretic and nonparetic limbs. Three of 349 identified records met the inclusion criteria. Small effect sizes were found in favor of physical activity in adults with chronic stroke (n=95, 40% female, average age 63·8 years, more than one-year poststroke). Patients in intervention groups had significantly higher changes in femoral neck bone mineral density, tibial cortical thickness and trabecular bone mineral content of the paretic limb, compared with controls (P<0·05). It is not known whether these benefits reduced fracture risk. There are limited studies investigating the skeletal effect of physical activity for adults poststroke. Given the increased risk of, and poor outcomes following a fracture after stroke, randomized trials are warranted to investigate the benefits of physical activity on bone, after stroke. Interventions are likely to be beneficial if implemented soon after stroke, when bone loss appears to be rapid and pronounced.

Analyses of muscular mass and function: the impact on bone mineral density and peak muscle mass

Bone density and bone mass are commonly regarded as the essential parameters to describe fracture risk in osteology. Because fractures primarily depend on bone strength and secondarily on bone mass and density, bone strength should be the main parameter to describe fracture risk. The quantitative description of bone strength has the prerequisite that bone geometry is assessed despite bone density. Thus, volumetric osteodensitometric methods should be preferred, which enable the physician to evaluate parameters primarily associated with bone modeling or remodeling. Modeling describes the adaptation of bone geometry to applied muscular forces in contrast to remodeling representing bone turnover. The adaptation of bone geometry to muscle forces led to the term functional muscle-bone unit, which enables the physician to differentiate between primary and secondary bone diseases. Primary bone diseases are characterized by a defective adaptation of bone to muscle forces in contrast to secondary bone diseases, which are primary diseases of the neuromuscular system. Because muscle forces are essential in the feedback loop of bone adaptation to forces (mechanostat), the assessment of muscle function has become an essential part of osteologic diagnostics in pediatrics. Dynamometric and mechanographic methods have been introduced to properly characterize kinetic aspects of muscle function in children and adolescents. Therefore, emphasis should be put on the assessment of muscle function despite the evaluation of osteodensitometric parameters in pediatric osteology.

Physical activity slows femoral bone loss but promotes wrist fractures in postmenopausal women: a 15-year follow-up of the OSTPRE study

Results on fracture risk among physically active persons are contradictory. The aim of this study was to investigate the long-term association between the self-reported physical activity (PA), the risk of fractures, and bone loss among peri- and postmenopausal women. The association between PA and fracture risk was examined during 15 years of follow-up in the population-based Osteoporosis Risk Factor and Prevention (OSTPRE) Study among 8560 women with a mean age of 52.2 years (range 47 to 56 years) at baseline. The amount and type of PA, as well as the types and mechanisms of fractures, were registered with self-administered questionnaires at 5-year intervals (ie, 1989, 1994, 1999, and 2004). A total of 2641 follow-up fractures were verified in 2073 women (24.2%). The study cohort was divided into quartiles by average hours of reported PA during the whole follow-up. Areal bone mineral density (aBMD) at the proximal femur (n = 2050) and lumbar spine (L(2)-L(4); n = 1417) was followed at 5-year intervals from a random stratified subsample with dual X-ray absorptiometry (DXA). Risk of fracture was estimated by using the Cox proportional hazards model with a mean follow-up time of 15.2 years. Weekly average time spent on leisure-time PA was 0.4, 1.7, 3.3, and 7.0 hours from the least to the most active quartiles, respectively. The risk of wrist fracture was higher in the active quartiles (II to IV) than in the most inactive quartile (I), with hazard ratios (HRs) of 1.3 [95% confidence interval (CI) 1.05-1.57, p = .014] for the second (II), 1.2 (95% CI 1.01-1.51, p = .045) for the third (III), and 1.4 (95% CI 1.14-1.69, p = .001) for the fourth (IV) quartile, respectively. Overall, most of the fractures were reported as a result of a fall (69.0%), with a 2.1 times higher rate of wrist fractures during the winter (November to April) than during summer season. There were no significant associations of PA with any other fracture types. Bone loss at the femoral neck, trochanter, and Ward's triangle was significantly associated with long-term PA (ANCOVA p < .05), whereas no associations of bone loss and PA in lumbar spine were seen. PA is associated with a moderate rise in wrist fracture risk, which might be explained in part by a higher number of outdoor activities. Regular PA of at least 1½ hours per week does not seem to increase the risk of other fractures and might significantly decrease proximal femur bone loss among peri- and postmenopausal women.

Comparison of pQCT-based measures of radial bone geometry and apparent trabecular bone structure using manufacturer and in-house-developed algorithms

Peripheral quantitative computed tomography (pQCT) provides noninvasive densitometric and morphometric measures of total, trabecular, and cortical bone compartments. Skeletal changes over time can be determined by repeated measurements. Image thickness of 2.5mm is thought to be advantageous with respect to test-retest reliability through interrogation of a significant tissue volume. However, the error associated with slight shifts in image location is unknown. The primary purpose of this study was to determine the effects of positional variability around the 4% site on radial bone measures. The secondary objective was to compare different software algorithms for estimating the same bone characteristics. Eight left cadaveric forearms (aged 65-88 yr) were imaged at 0.5-mm intervals around the 4% site of the radial bone using pQCT (10 slices; in-plane resolution: 0.2 × 0.2mm; thickness: 2.5mm; Stratec XCT2000L. We used the manufacturer's software (Stratec v6.0B) to determine the total bone mineral density (BD_tot), total bone mineral content (BMC_tot), total bone area (Area_tot), trabecular bone mineral density (BD_trab), trabecular bone mineral content (BMC_trab), and trabecular bone area (Area_trab) from each image. For comparison, in-house-developed software was also used to analyze Area_tot and Area_trab at the 4% site. The in-house software also produced measures of apparent trabecular structure, including number (App.Tb.N), thickness (App.Tb.Th), and spacing (App.Tb.Sp), quantified using 2 different stereological approaches: the parallel-plate method using trabecular perimeter lengths and mean intercept length analysis. The effect of slice position was assessed using a 1-way repeated-measures analysis of variance (ANOVA). Reliability of nonsignificant slice distances around the 4% site was determined using intraclass correlation coefficients (ICCs). One-way repeated-measures ANOVA was used to compare measures of similar bone characteristics at the 4% site. Bland-Altman plots were created to assess the level of agreement between pairs of algorithms quantifying comparable apparent trabecular structure. Area_tot and Area_trab differed significantly at greater than or equal to 1.0mm proximal and greater than or equal to 0.5mm distal to the 4% site. BMC_tot and BMC_trab differ significantly greater than or equal to 1.5mm proximally (for both) and greater than or equal to 2.0 and 1.0mm distally, respectively. BD_tot differed significantly at greater than or equal to 1mm proximal and distal to the 4% site. BD_trab did not differ among the 10 slices. For images acquired at the 4% site, and 0.5mm more proximally, reliability was excellent (ICC=0.98 to 0.99). Although the in-house software yielded a higher value for Area_tot and Area_trab at the 4% site (p<0.05), no systematic bias was observed. The parallel-plate method yielded higher values for App.Tb.N and lower values for App.Tb.Th (p<0.05), with no systematic bias. App.Tb.Sp values were smaller using the parallel-plate method, and the difference in methods increased as App.Tb.Sp values increased. Statistically, tolerance for repositioning around the 4% site of the radial bone is least for measures of bone area and greatest for BD_trab. On repeated measures, a proximal shift of 0.5mm will not influence the results.

Effects of lifetime loading history on cortical bone density and its distribution in middle-aged and older men

We have reported previously that long-term participation of weight-bearing exercise is associated with increased QCT-derived cortical bone size and strength in middle-aged and older men, but not whole bone cortical volumetric BMD. However, since bone remodeling and the distribution of loading-induced strains within cortical bone are non-uniform, the aim of this study was to examine the effects of lifetime loading history on cortical bone mass distribution and bone shape in healthy community dwelling middle-aged and older men. We used QCT to assess mid-femur and mid-tibia angular bone mass distribution around its center (polar distribution), the bone density distribution through the cortex (radial distribution), and the ratio between the maximum and minimum moments of inertia (I(max)/I(min) ratio) in 281 men aged 50 to 79 years. Current (>50 years) and past (13-50 years) sport and leisure time activity was assessed by questionnaire to calculate an osteogenic index (OI) during adolescence and adulthood. All men were then categorized into a high (H) or low/non impact (L) group according to their OI scores in each period. Three contrasting groups were then formed to reflect weight-bearing impact categories during adolescence and then adulthood: H-H, H-L and L-L. For polar bone mass distribution, bone deposition in the anterolateral, medial and posterior cortices were 6-10% greater at the mid-femur and 9-24% greater at mid-tibia in men in the highest compared to lowest tertile of lifetime loading (p<0.01-<0.001). When comparing the influence of contrasting loading history during adolescence and adulthood, there was a graded response between the groups in the distribution of bone mass at the anterior-lateral and posterior regions of the mid-tibia (H-H>H-L>L-L). For radial bone density distribution, there were no statistically significant effects of loading at the mid-femur, but a greater lifetime OI was associated with a non-significant 10-15% greater bone density near the endocortical region of the mid-tibia. In conclusion, a greater lifetime loading history was associated with region-specific adaptations in cortical bone density.

Effects of tai chi exercise on posturography, gait, physical function and quality of life in postmenopausal women with osteopaenia: a randomized clinical study

OBJECTIVE

to evaluate the effects of tai chi exercise on risk factors for falls in postmenopausal women with osteopaenia through measurements of balance, gait, physical function and quality of life.

DESIGN

a randomized, controlled, single-blinded, 24-week trial with stratification by age and bone mass.

SETTING

general community.

PARTICIPANTS

Sixty-one independently living elderly females aged 65 years and older with low bone mass.

INTERVENTIONS

subjects were recruited and randomly assigned to 24 weeks of tai chi (60 minutes/session, three sessions/week, n = 30) or a control group (n = 31).

OUTCOME MEASURES

computerized dynamic posturography, gait, 'timed up and go', five-chair sit-to-stand and quality of life assessed at baseline, 12 and 24 weeks.

RESULTS

after 24 weeks, subjects in the tai chi group demonstrated an increase in stride width (P = 0.05) and improvement in general health (P = 0.008), vitality (P = 0.02) and bodily pain (P = 0.03) compared with those in the control group. There was no significant difference in balance parameters, 'timed up and go', five-chair sit-to-stand and other domains of quality of life.

CONCLUSION

tai chi exercise may reduce risk factors for falls by increasing the stride width, and may improve quality of life in terms of general health, vitality and bodily pain in postmenopausal women with osteopaenia.

Muscle power and physical activity are associated with bone strength in older men: The osteoporotic fractures in men study

The purpose of these analyses was to explore whether physical activity score, leg power or grip strength were associated with tibia and radius estimates of bone strength, cortical density, or total bone area. Peripheral quantitative computed tomography (pQCT) was used to compare tibial and radial bone volumetric density (vBMD, mg/cm(3)), total (ToA, mm(2)) and cortical (CoA, mm(2)) bone area, and estimates of bone compressive strength (bone strength index, BSI) and bending strength (polar strength strain index, SSIp) in a subset (n=1171) of men (> or = 65 years) who participated in the multi-site Osteoporotic Fractures in Men (MrOS) study. Physical activity was assessed by questionnaire (PASE), leg power by Nottingham Power Rig, and grip strength by a hand-held Dynamometer. Participants were categorized into quartiles of PASE, grip strength or leg power. The model was adjusted for age, race, clinic, weight, and limb length. In the tibia, BSI (+7%) and SSIp (+4%) were highest in the most active physically quartile compared to the least active (p<0.05). At the 4% site of the tibia, men with the greatest leg power had both greater ToA (+5%, p<0.001) and BSI (+5.3%, p=0.086) compared to men with the least leg power. At the 66% site of the tibia, the men with the highest leg power, compared to the men with the lowest leg power, had greater ToA (+3%, p=0.045) SSIp (+5%, p=0.008). Similar results were found at both the distal and midshaft of the radius. The findings of this study suggest the importance of maintaining levels of physical activity and muscle strength in older men to prevent bone fragility.

Targeted exercise against osteoporosis: A systematic review and meta-analysis for optimising bone strength throughout life

BACKGROUND

Exercise is widely recommended to reduce osteoporosis, falls and related fragility fractures, but its effect on whole bone strength has remained inconclusive. The primary purpose of this systematic review and meta-analysis was to evaluate the effects of long-term supervised exercise (> or =6 months) on estimates of lower-extremity bone strength from childhood to older age.

METHODS

We searched four databases (PubMed, Sport Discus, Physical Education Index, and Embase) up to October 2009 and included 10 randomised controlled trials (RCTs) that assessed the effects of exercise training on whole bone strength. We analysed the results by age groups (childhood, adolescence, and young and older adulthood) and compared the changes to habitually active or sedentary controls. To calculate standardized mean differences (SMD; effect size), we used the follow-up values of bone strength measures adjusted for baseline bone values. An inverse variance-weighted random-effects model was used to pool the results across studies.

RESULTS

Our quality analysis revealed that exercise regimens were heterogeneous; some trials were short in duration and small in sample size, and the weekly training doses varied considerably between trials. We found a small and significant exercise effect among pre- and early pubertal boys [SMD, effect size, 0.17 (95% CI, 0.02-0.32)], but not among pubertal girls [-0.01 (-0.18 to 0.17)], adolescent boys [0.10 (-0.75 to 0.95)], adolescent girls [0.21 (-0.53 to 0.97)], premenopausal women [0.00 (-0.43 to 0.44)] or postmenopausal women [0.00 (-0.15 to 0.15)]. Evidence based on per-protocol analyses of individual trials in children and adolescents indicated that programmes incorporating regular weight-bearing exercise can result in 1% to 8% improvements in bone strength at the loaded skeletal sites. In premenopausal women with high exercise compliance, improvements ranging from 0.5% to 2.5% have been reported.

CONCLUSIONS

The findings from our meta-analysis of RCTs indicate that exercise can significantly enhance bone strength at loaded sites in children but not in adults. Since few RCTs were conducted to investigate exercise effects on bone strength, there is still a need for further well-designed, long-term RCTs with adequate sample sizes to quantify the effects of exercise on whole bone strength and its structural determinants throughout life.

Physical therapy approaches to reduce fall and fracture risk among older adults

Falls and fall-related injuries, such as fractures, are a growing problem among older adults, often causing longstanding pain, functional impairments, reduced quality of life and excess health-care costs and mortality. These problems have led to a variety of single component or multicomponent intervention strategies to prevent falls and subsequent injuries. The most effective physical therapy approach for the prevention of falls and fractures in community-dwelling older adults is regular multicomponent exercise; a combination of balance and strength training has shown the most success. Home-hazard assessment and modification, as well as assistive devices, such as canes and walkers, might be useful for older people at a high risk of falls. Hip protectors are effective in nursing home residents and potentially among other high-risk individuals. In addition, use of anti-slip shoe devices in icy conditions seems beneficial for older people walking outdoors. To be effective, multifactorial preventive programs should include an exercise component accompanied by individually tailored measures focused on high-risk populations. In this Review, we focus on evidence-based physical therapy approaches, including exercise, vibration training and improvements of safety at home and during periods of mobility. Additionally, the benefits of multifaceted interventions, which include risk factor assessment, dietary supplements, elements of physical therapy and exercise, are addressed.

Physical approach for prevention and treatment of osteoporosis

Osteoporosis and its consequent fractures are a major problem in public health. To complement the conventional pharmacological treatment for this metabolic disease, non-pharmacological treatment options have been developed in the last decades. Several studies demonstrate that physical exercise programs including impact exercises, specific strength training, balance and coordination training may maintain or increase spine and hip bone mineral density as well as decrease the frequency of falls among osteoporotic and osteopenic patients. Furthermore, some physical agents such as vibratory platforms, low intensity electrical stimulation, laser therapy and ultrasound show positive effects on osteoporotic tissue as well. Consequently, while planning treatment for an osteoporotic patient, non-pharmacological management options should be considered and integrated to the conventional treatment in order to maximize its effects and improve the quality of life of these patients.