Has exercise an antifracture efficacy in women?

Impact of changes in physical activity and incident fracture after acute ischemic stroke

Stroke survivors are at an increased risk of falls and fractures. Physical activity is inversely associated with the fracture risk in the general population. However, the association between incident fracture risk and changes in habitual physical activity before and after an index stroke remains unclear. This study attempted to explore the association between incident fracture risk and changes in physical activity after stroke. Using the claims database of the National Health Insurance Program in Korea, participants with their first ischemic stroke between 2010 and 2016 were enrolled in the study. The participants were divided into four groups according to changes in physical activity habits evaluated using two consecutive self-reported questionnaires before and after stroke, if available: persistent non-exercisers, exercise dropouts, new exercisers, and persistent exercisers. The primary outcome was a composite of vertebral, hip, and other fractures. We performed multivariable Cox proportional hazard regression analysis and provided adjusted hazard ratios and 95% confidence intervals for each outcome. Among 202,234 participants included from 1,005,879 datasets, 16,621 (8.22%) experienced any type of fracture as the primary outcome. After multivariable adjustment, exercise dropouts (n = 37,106), new exercisers (n = 36,821), and persistent exercisers (n = 74,647) had a significantly reduced risk of any type of fracture (aHR 0.932, 95% CI 0.893-0.973; aHR 0.938, 95% CI 0.900-0.978; aHR 0.815, 95% CI 0.780-0.852, respectively) compared to the persistent non-exercisers (n = 53,660). Furthermore, regardless of pre-stroke exercise status, those who exercised ≥ 1000 metabolic equivalents of tasks post-stroke had a significantly reduced risk of fractures. Initiating or continuing moderate-to-vigorous regular physical activity after acute ischemic stroke was associated with a significantly lower risk of incident fractures, including hip, vertebral, and other types.

Exercise as Medicine for Older Women

Exercise is associated with protective effects, yet most adult women in this country do not meet the physical activity recommendations set forth in the Physical Activity Guidelines for Americans. This article discusses how exercise affects disease and prevents functional decline. It also clarifies why exercise is not a generic cure-all but is instead a tool physicians can use with precision to affect a myriad of health issues. Specifics will be provided regarding physical fitness assessments and comprehensive treatments and how physicians can be more involved in using physical fitness to keep their older female patients healthy.

Effects of Small-Sided Soccer Games on Physical Fitness, Physiological Responses, and Health Indices in Untrained Individuals and Clinical Populations: A Systematic Review

BACKGROUND

Small-sided soccer games (SSSG) are a specific exercise regime with two small teams playing against each other on a relatively small pitch. There is evidence from original research that SSSG exposure provides performance and health benefits for untrained adults.

OBJECTIVES

The aim of this systematic review was to summarize recent evidence on the acute and long-term effects of SSSG on physical fitness, physiological responses, and health indices in healthy untrained individuals and clinical populations.

METHODS

This systematic literature search was conducted in four electronic databases (PubMed, Web of Science, SPORTDiscus) from inception until June 2019. The following key terms (and synonyms searched for by the MeSH database) were included and combined using the operators "AND", "OR", "NOT": ((soccer OR football) AND ("soccer training" OR "football training" OR "soccer game*" OR "small-sided soccer game*") AND ("physical fitness" OR "physiological adaptation*" OR "physiological response*" OR health OR "body weight" OR "body mass" OR "body fat" OR "bone composition" OR "blood pressure")). The search syntax initially identified 1145 records. After screening for titles, abstracts, and full texts, 41 studies remained that examined the acute (7 studies) and long-term effects (34 studies) of SSSG-based training on physical fitness, physiological responses, and selected alth indices in healthy untrained individuals and clinical populations.

RESULTS

No training-related injuries were reported in the 41 acute and long-term SSSG studies. Typically, a single session of SSSG lasted 12-20 min (e.g., 3 × 4 min with 3 min rest or 5 × 4 min with 4 min rest) involving 4-12 players (2 vs. 2 to 6 vs. 6) at an intensity ≥ 80% of HR_max. Following single SSSG session, high cardiovascular and metabolic demands were observed. Specifically, based on the outcomes, the seven acute studies reported average heart rates (HR) ≥ 80% of HR_max (165-175 bpm) and mean blood lactate concentrations exceeding 5 mmol/l (4.5-5.9 mmol/l) after single SSSG sessions. Based on the results of 34 studies (20 with healthy untrained, 10 with unhealthy individuals, and 4 with individuals with obesity), SSSG training lasted between 12 and 16 weeks and was performed 2-3 times per week. SSSG had positive long-term effects on physical fitness (e.g., Yo-Yo IR1 performance), physiological responses including maximal oxygen uptake (VO_2max) [+ 7 to 16%], and many health-related markers such as blood pressure (reductions in systolic [- 7.5%] and diastolic [- 10.3%] blood pressure), body composition (decreased fat mass [- 2 to - 5%]), and improved indices of bone health (bone mineral density: [+ 5 to 13%]; bone mineral content: [+ 4 to 5%]), and metabolic (LDL-cholesterol [- 15%] as well as cardiac function (left-ventricular internal diastolic diameter [+ 8%], end diastolic volume [+ 21%], left-ventricular mass index [+ 18%], and left-ventricular ejection fraction [+ 8%]). Irrespective of age or sex, these health benefits were observed in both, untrained individuals and clinical populations.

CONCLUSIONS

In conclusion, findings from this systematic review suggest that acute SSSG may elicit high cardiovascular and metabolic demands in untrained healthy adults and clinical populations. Moreover, this type of exercise is safe with positive long-term effects on physical fitness and health indices. Future studies are needed examining the long-term effects on physical fitness and physiological adaptations of different types of SSSG training (e.g., 3 vs. 3; 6 vs. 6) in comparison to continuous or interval training in different cohorts.

Editorial. The Challenges of Orthopaedic Trauma in Spain

Spain is considered the healthiest nation in the world, due to lifepromoting aspects such as good diet, care facilities and a favourable family environment. However, although increased life expectancy is an indicator of development, it may have a negative impact on the other two variables of health service efficiency, namely health expenditure per capita and its relative weight in Gross Domestic Product.

The effects of long-term whole-body vibration and aerobic exercise on body composition and bone mineral density in obese middle-aged women

PURPOSE

The purpose of this study was to determine the effectiveness of whole-body passive vibration exercise and its differences from aerobic exercise on body composition, bone mineral density (BMD) and bone mineral content (BMC).

METHODS

Obese middle-aged women (n=33 out of 45) with 34±3% body fat completed the training protocol. They were randomly assigned into diet (n=9; control group), diet plus whole-body vibration exercise (n=13; vibration group), and diet plus aerobic exercise (n=11; aerobic group) groups and we compared their body composition, BMD, and BMC before and after 9 months of training. There were no significant differences in nutrient intake among groups during the training period.

RESULTS

Relative body fat (%) decreased significantly (p < .05) in all three groups and the exercise groups showed a greater reduction in fat mass than the diet only group. BMD in the whole body, lumbar spine, hip and forearm were not significantly different among the three groups. Total body BMC increased significantly in the vibration group throughout the first 6 months of training.

CONCLUSION

Results suggest that long- term vibration training when used in conjunction with a diet program is as effective as aerobic exercise with a diet program in improving body composition of obese middle-aged women without compromising BMC or BMD. Thus, it can be considered a novel and effective method for reducing body fat.

Sclerostin antibody prevented progressive bone loss in combined ovariectomized and concurrent functional disuse

Osteoporosis is characterized by low bone mass and compromised trabecular architecture, and is commonly occurred in post-menopausal women with estrogen deficiency. In addition, prolonged mechanical unloading, i.e., long term bed rest, can exaggerate the bone loss. Sclerostin is a Wnt signaling antagonist and acts as a negative regulator for bone formation. A sclerostin-neutralizing antibody (Scl-Ab) increased bone mineral density in women with postmenopausal osteoporosis and healthy men. The objective of this study was to characterize the condition of bone loss in ovariectomized (OVX) rats with concurrent mechanical unloading and evaluate the effect of sclerostin antibody treatment in mitigating the prospective severe bone loss conditions in this model. Four-month-old OVX- or sham-operated female SD rats were used in this study. They were subjected to functional disuse induced by hind-limb suspension (HLS) or free ambulance after 2days of arrival. Subcutaneous injections with either vehicle or Scl-Ab at 25mg/kg were made twice per week for 5weeks from the time of HLS. μCT analyses demonstrated a significant decrease in distal metaphyseal trabecular architecture integrity with HLS, OVX and HLS+OVX (bone volume fraction decreased by 29%, 71% and 87% respectively). The significant improvements of various trabecular bone parameters (bone volume fraction increased by 111%, 229% and 297% respectively as compared with placebo group) with the administration of Scl-Ab are associated with stronger mechanical property and increased bone formation by histomorphometry. These results together indicate that Scl-Ab prevented the loss of trabecular bone mass and cortical bone strength in OVX rat model with concurrent mechanical unloading. The data suggested that monoclonal sclerostin-neutralizing antibody represents a promising therapeutic approach for severe osteoporosis induced by estrogen deficiency with concurrent mechanical unloading.

Change in bone mineral density during adjuvant chemotherapy for early-stage breast cancer

Purpose

Adjuvant chemotherapy has been associated with loss of bone mineral density (BMD) either as a direct effect or due to glucocorticoids used as supportive care medication. A prospective cohort study was conducted to evaluate changes in BMD from baseline to right after completion of chemotherapy, i.e., 4 months.

Methods

Dual-imaging X-ray absorptiometry (DXA) was performed at baseline and after completing anthracycline- and taxane-based chemotherapy to measure BMD in the spine, hip, and forearm in early-stage breast cancer patients. High-dose prednisolone was used at three weekly intervals to reduce nausea and vomiting. Patients were advised a daily calcium/vitamin D supplement. Linear regression was used to assess mean percentage change in BMD and 95 % confidence intervals (95 % CI) according to doses of prednisolone, menopausal status, smoking, and BMI.

Results

Eight patients were excluded: seven because of initiation of bisphosphonate treatment due to osteoporosis at baseline, and one had non-interpretable DXA. The final cohort included 97 patients with a mean age of 53 years (range 34–72). Mean cumulative prednisolone dose was 1308 mg (95 % CI 1255; 1362). BMD increased 1.36 % (95 % CI 0.7; 2.0, p < 0.001) in the spine and 1.27 % (95 % CI 0.9; 1.7, p < 0.001) in the hip. Forearm BMD did not change. Postmenopausal women had increases in spine BMD of 2.35 % (95 % CI 1.1; 3.6, p < 0.001) compared to premenopausal women. The spine BMD of current smokers decreased 1.67 % (95 % CI −3.3; −0.1, p = 0.04) compared to never/former smokers.

Conclusions

Adjuvant chemotherapy supplemented with prednisolone was not associated with loss of BMD. Postmenopausal women gained bone mass, whereas current smokers lost bone mass.

Effects of recreational soccer on physical fitness and health indices in sedentary healthy and unhealthy subjects

Recreational soccer (RS) is becoming a popular alternative to the classical continuous exercise mode used for the improvement of cardiovascular and metabolic fitness in untrained people. The objective of this paper was to conduct a detailed systematic review of the literature, identifying the physiological responses to RS and the training effects of RS on aerobic fitness and health in untrained healthy individuals and clinical patients. PubMed, Google Scholar and ScienceDirect databases were searched using terms related to recreational soccer. Inclusion criteria were randomized controlled trials (RCT) that assessed acute physiological responses to RS or the training effects of RS on physical fitness and health in sedentary, untrained subjects of any age or health status. All studies were assessed for methodological quality using the PEDro scale. Thirty-five articles met the inclusion criteria; seven examined the acute response to RS, and 28 assessed training effects. Clear evidence was found that RS had positive effects on many health-related indices and variables, including VO₂max (gains of 7-16%), blood pressure (reductions of 6-13 mmHg), body composition (decreased fat mass and improved indices of bone health), and metabolic and cardiac function. These positive effects were observed in both healthy individuals and clinical patients, irrespective of age or sex. Although this review provides clear evidence of the positive effects of RS on health, most studies had limitations of methodology (an average PEDro score < 6). Furthermore, many of the training studies were from a small number of research groups. Future studies should be extended to other countries and institutions to ensure generality of the results. Regular RS training leads to significant cardiovascular and muscular adaptations and gains of health both in sedentary individuals and clinical patients at all ages, suggesting that RS is a potentially highly motivational method to enhance population health.

Body mass index, physical activity, and fracture among young adults: longitudinal results from the Thai cohort study

Background

We investigated risk factors for fracture among young adults, particularly body mass index (BMI) and physical activity, which although associated with fracture in older populations have rarely been investigated in younger people.

Methods

In 2009, 4 years after initial recruitment, 58 204 Thais aged 19 to 49 years were asked to self-report fractures incident in the preceding 4 years. Conditional logistic regression was used to calculate odds ratios (ORs) and 95% CIs for associations of fracture incidence with baseline BMI and physical activity.

Results

Very obese women had a 70% increase in fracture risk (OR = 1.73, 95% CI 1.21–2.46) as compared with women with a normal BMI. Fracture risk increased by 15% with every 5-kg/m² increase in BMI. The effects were strongest for fractures of the lower limbs. Frequent purposeful physical activity was also associated with increased fracture risk among women (OR = 1.52, 95% CI 1.12–2.06 for 15 episodes/week vs none). Neither BMI nor physical activity was associated with fracture among men, although fracture risk decreased by 4% with every additional 2 hours of average sitting time per day (OR = 0.96, 95% CI 0.93–0.99).

Conclusions

The increase in obesity prevalence will likely increase fracture burden among young women but not young men. While active lifestyles have health benefits, our results highlight the importance of promoting injury prevention practices in conjunction with physical activity recommendations, particularly among women.

Intakes of selected nutrients, bone mineralisation and density of adolescent female swimmers over a three-year period

The aim of this study was to conduct three-year monitoring of bone mineralization (BMC) and bone mineral density (BMD) of adolescent girls engaged in swimming at the time of attaining the peak bone mass and of their counterparts leading a rather sedentary life, considering the intakes of calcium, phosphorus and protein, as well as the proportions among those nutrients. Two groups of girls aged 11-13 years were studied 3 times at yearly intervals: untrained controls (n = 20) and those engaged in competitive swimming (n = 20). Bone density was determined by dual-energy X-ray absorptiometry (DXA) in the lumbar spine (L2 - L4). Nutrient intakes (energy, protein, calcium, phosphorus) were assessed from 24-h recalls. The group of swimmers had significantly lower BMI values than the control group. No systematic, significant between-group differences were found in nutrient intake or in bone mineralization variables. Calcium intake was below the recommended norm in all subjects but mean values of bone mineralization variables (BMC, BMD) steadily increased in both groups. The BMD z-scores proved negative throughout the three-year period of early adolescence in both groups of girls and that decrease was significant in swimmers. This could have been due to insufficient calcium intake as well as to inadequate calcium-to-phosphate and protein-to-calcium ratios and, when continued, might result in a decreased bone mass in adulthood.

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.

Effects of resistance training on matrix metalloproteinase-2 activity and biomechanical and physical properties of bone in ovariectomized and intact rats

The purpose of this study was to investigate the influence of resistance training on the activity of matrix metalloproteinase (MMP)-2 and bone biomechanical properties in ovariectomized and intact rats. Forty-eight female rats were divided into two distinct groups, ovariectomized (OVX) and intact (Int), which were subdivided into three similar subgroups: sedentary, acute exercise and chronic exercise. Rats performed a resistance training for 12 weeks in which animals climbed a vertical ladder of 1.1 m with weights attached to their tails. Sessions were performed with an interval of 3, 4-9 and 8-12 days scaled dynamic movements of climbing. Biomechanical and physical analyses were performed using a universal testing machine, and MMP-2 activity analysis by zymography. Bone density (BD), mineral density (MD), maximum load and fracture load was reduced in sedentary and acute exercise OVX groups compared with the sedentary intact group (P<0.05); in contrast, chronically trained groups (OVX and Int) showed a significant increase in BD, MD and fracture load compared with all the other groups. MMP-2 activity in chronically trained groups also showed a significant increase, while the sedentary OVX group showed a decrease in MMP-2 activity compared with the intact sedentary group (P<0.05). Our results suggest that the resistance training proposed in our work was efficient in reverting the deleterious effects of ovariectomy on bone tissue, and also produced modeling effects in intact rats. On the other hand, ovariectomy reduced the activity of MMP-2 and produced deleterious effects on bone tissue, mimicking menopause intrinsically.

Loading and skeletal development and maintenance

Mechanical loading is a major regulator of bone mass and geometry. The osteocytes network is considered the main sensor of loads, through the shear stress generated by strain induced fluid flow in the lacuno-canalicular system. Intracellular transduction implies several kinases and phosphorylation of the estrogen receptor. Several extra-cellular mediators, among which NO and prostaglandins are transducing the signal to the effector cells. Disuse results in osteocytes apoptosis and rapid imbalanced bone resorption, leading to severe osteoporosis. Exercising during growth increases peak bone mass, and could be beneficial with regards to osteoporosis later in life, but the gain could be lost if training is abandoned. Exercise programs in adults and seniors have barely significant effects on bone mass and geometry at least at short term. There are few data on a possible additive effect of exercise and drugs in osteoporosis treatment, but disuse could decrease drugs action. Exercise programs proposed for bone health are tedious and compliance is usually low. The most practical advice for patients is to walk a minimum of 30 to 60 minutes per day. Other exercises like swimming or cycling have less effect on bone, but could reduce fracture risk indirectly by maintaining muscle mass and force.

Long-term musculoskeletal and cardiac health effects of recreational football and running for premenopausal women

We examined long-term musculoskeletal and cardiac adaptations elicited by recreational football (FG, n=9) and running (RG, n=10) in untrained premenopausal women in comparison with a control group (CG, n=9). Training was performed for 16 months ( approximately 2 weekly 1-h sessions). For FG, right and left ventricular end-diastolic diameters were increased by 24% and 5% (P<0.05), respectively, after 16 months. Right ventricular systolic function measured by tricuspid annular plane systolic excursion (TAPSE) increased (P<0.05) in FG after 4 months and further (P<0.05) after 16 months (15% and 32%, respectively). In RG and CG, cardiac structure, E/A and TAPSE remained unchanged. For FG, whole-body bone mineral density (BMD) was 2.3% and 1.3% higher (P<0.05) after 16 months, than after 4 and 0 months, respectively, with no changes for RG and CG. FG demonstrated substantial improvements (P<0.05) in fast (27% and 16%) and slow (16% and 17%) eccentric muscle strength and rapid force capacity (Imp30ms: 66% and 65%) after 16 months compared with 4 and 0 months, with RG improving Imp30ms by 64% and 46%. In conclusion, long-term recreational football improved muscle function, postural balance and BMD in adult women with a potential favorable influence on the risk of falls and fractures. Moreover, football training induced consistent cardiac adaptations, which may have implications for long-term cardiovascular health.

The effect of ovariectomy combined with hindlimb unloading and reloading on the long bones of mature Sprague-Dawley rats

OBJECTIVE

To determine the effect of loss of ovarian function and mechanical loading (ie, inactivity) alone or in combination on bone mass and strength.

DESIGN

Mature (aged 6 mo) rats were ovariectomized to induce loss of ovarian function and bone. Hindlimb unloading (HLU) was used to determine the effect of mechanical unloading and reloading on bone mass and strength. Bone mass of the femur and tibia was determined using dual-energy x-ray absorptiometry. Femoral and tibial bone strength was determined by a three-point bending test and by a torsion test.

RESULTS

Ovariectomy (OVX) alone decreased total bone mineral density (BMD) in the femur (-5.5%, P=0.03) and tibia (-7.3%, P=0.01) compared with that for sham-operated animals. HLU alone for 4 weeks had no significant effect on bone. Together OVX/HLU accentuated BMD loss in the femur (-10.5%, P<0.01) compared with that for sham-operated animals. The femur was more sensitive than the tibia to the combination of OVX/HLU, indicated by the reduction (-5.3%, P<0.05) of total BMD below that achieved by OVX alone. Torsion tests showed that OVX/HLU but not OVX or HLU alone reduced bone strength. There was a correlation between lower femoral total BMD (r2=0.65, P<0.001) and reduced torque strength. Bone loss did not continue during the 2 weeks of reloading.

CONCLUSIONS

OVX accompanied by mechanical unloading results in more rapid and severe bone loss than either OVX or unloading alone and therefore is associated with a greater likelihood of osteoporosis.

The association between physical activity and osteoporotic fractures: a review of the evidence and implications for future research

PURPOSE

Physical activity helps maintain mobility, physical functioning, bone mineral density (BMD), muscle strength, balance and, therefore, may help prevent falls and fractures among the elderly. Meanwhile, it is theoretically possible that physical activity increases risk of fractures as it may increase risk of falls and has only a modest effect on BMD. This review aims to assess the potential causal association between physical activity and osteoporotic fractures from an epidemiological viewpoint.

METHODS

As the medical literature lacks direct evidence from randomized controlled trials (RCTs) with fracture end points, a meta-analysis of 13 prospective cohort studies with hip fracture end point is presented. The current evidence base regarding the link between exercise and fracture risk determinants (namely, falls, BMD, and bone quality) are also summarized.

RESULTS

Moderate-to-vigorous physical activity is associated with a hip fracture risk reduction of 45% (95% CI, 31-56%) and 38% (95% CI, 31-44%), respectively, among men and women. Risk of falling is suggested to be generally reduced among physically active people with a potential increased risk in the most active and inactive people. Positive effects of physical activity on BMD and bone quality are of a questionable magnitude for reduction of fracture risk.

CONCLUSION

The complexity of relationship between physical activity and osteoporotic fractures points out to the need for RCTs to be conducted with fractures as the primary end point.

Impact exercise increases BMC during growth: an 8-year longitudinal study

Our aim was to assess BMC of the hip over 8 yr in prepubertal children who participated in a 7-mo jumping intervention compared with controls who participated in a stretching program of equal duration. We hypothesized that jumpers would gain more BMC than control subjects. The data reported come from two cohorts of children who participated in separate, but identical, randomized, controlled, school-based impact exercise interventions and reflect those subjects who agreed to long-term follow-up (N = 57; jumpers = 33, controls = 24; 47% of the original participants). BMC was assessed by DXA at baseline, 7 and 19 mo after intervention, and annually thereafter for 5 yr (eight visits over 8 yr). Multilevel random effects models were constructed and used to predict change in BMC from baseline at each measurement occasion. After 7 mo, those children that completed high-impact jumping exercises had 3.6% more BMC at the hip than control subjects whom completed nonimpact stretching activities (p < 0.05) and 1.4% more BMC at the hip after nearly 8 yr (BMC adjusted for change in age, height, weight, and physical activity; p < 0.05). This provides the first evidence of a sustained effect on total hip BMC from short-term high-impact exercise undertaken in early childhood. If the benefits are sustained into young adulthood, effectively increasing peak bone mass, fracture risk in the later years could be reduced.

Jump starting skeletal health: a 4-year longitudinal study assessing the effects of jumping on skeletal development in pre and circum pubertal children

INTRODUCTION

Evidence suggests bone mineral increases attributable to exercise training prior to puberty may confer a significant advantage into adulthood. However, there is a dearth of supportive prospective longitudinal data. The purpose of this study was to assess bone mineral content (BMC) of the whole body (WB), total hip (TH), femoral neck (FN) and lumbar spine (LS) over four years in pre-pubertal boys and girls following a 7-month jumping intervention.

METHODS

The study population included 107 girls and 98 boys aged 8.6+/-0.88 years at baseline. Participating schools were randomly assigned as either intervention or control school. Children at the intervention school (n=101) participated in a jumping intervention embedded within the standard PE curriculum. The control school children (n=104) had similar exposure to PE without the jumping intervention. BMC was assessed by DXA at baseline, at 7-month post intervention, and annually thereafter for three years totaling 5 measurement opportunities. Multi-level random effects models were constructed and used to predict change from study entry in BMC parameters at each measurement occasion.

RESULTS

A significant intervention effect was found at all bone sites. The effect was greatest immediately following the intervention (at 7 months) but still significant three years after the intervention. At 7 months, intervention participants had BMC values that were 7.9%, 8.4%, 7.7% and 7.3% greater than the controls at the LS, TH, FN and WB, respectively (p<0.05), when the confounders of age, maturity and tissue mass were controlled. Three years after the intervention had concluded the intervention group had 2.3%, 3.2%, 4.4% and 2.9% greater BMC than controls at the LS, TH, FN and WB respectively (p<0.05), when the confounders of age, maturity and tissue mass were controlled.

CONCLUSIONS

This provides evidence that short-term high impact exercise in pre-puberty has a persistent effect over and above the effects of normal growth and development. If the benefits are sustained until BMC plateaus in early adulthood, this could have substantial effects on fracture risk.

Physical activity and fracture risk: a prospective study of 1898 incident fractures among 34,696 British men and women

Regular physical activity is believed to have a beneficial effect on bone health but may also increase the risk of fractures by increasing the incidence of injury. We examined the association between physical activity and fracture risk in a prospective study of self-reported incident fractures among 34 696 men and women aged 20 to 89 years in the United Kingdom. Over an average of 5.2 years of follow-up, 343 men and 1555 women reported one or more fractures. For the 72% of fractures caused by a fall, the only significant association with physical activity was the lower fracture rate among women with a standing occupation compared with women in sedentary or no employment [incidence rate ratio, 0.81 (95% CI, 0.69-0.95)]. There was a strong positive association between bicycling and fracture risk: P < 0.001 for trend for both sexes. Regular participation in exercise and sports other than walking and bicycling was also associated with an increased fracture risk, and fracture rates were significantly higher for male manual workers compared with men in sedentary or no employment. These positive associations of physical activity with fracture risk applied primarily to fractures not caused by a fall. The relatively low fracture risk among women with a standing occupation might be the result of a beneficial effect of weight-bearing exercise. The markedly increased risk of fractures associated with bicycling, and the moderately increased risk associated with other exercise and sports, are probably the result of an increased incidence of injury.

Relationships between physical activity and physical capacity in adolescent females and bone mass in adulthood

This study investigates whether physical activity and physical performance in adolescence are positively related to adult bone mineral density (BMD). In 1974, physical activity, endurance, and muscular strength were measured in 204 randomly selected female students, age 16.1 +/- 0.3 year (range 15-17 years). Twenty years later, 36 of the women volunteered to undergo a measurement of their BMD. Women who were members in a sports club in adolescence had significantly higher adult BMD (mean differences of 5% to 17% depending on site) compared with subjects who were not engaged in a sports club. Furthermore, women with persistent weight-bearing activity in adulthood had significantly higher BMD compared with women who had stopped being active or had never been active. The differences ranged between 5% and 19% with the highest difference found in trochanter BMD. Stepwise regression analyses showed that membership in a sports club at baseline was a significant independent predictor of BMD in the total body, lumbar spine, legs, trochanter, and femoral neck, explaining 17-26% of the variation in BMD. Change in body weight was a strong independent predictor of BMD of the total body and arms, explaining 8% of the variation in both sites. In addition, running performance at baseline was an independent predictor of total body BMD, whereas the two-hand lift performance significantly predicted BMD of the total body, legs and trochanter. The hanging leg-lift and handgrip were both significant predictors of arm BMD. In conclusion, membership in a sports club and site-specific physical performance in adolescence together with the change in body weight were significantly associated with adult BMD in premenopausal women.

‘The only place to go and be in the city’: women talk about exercise, being outdoors, and the meanings of a large urban park

This article explores women's physical activities in an urban park in Brooklyn, NY, USA. Physical inactivity is a growing health concern, and research has begun to address the physical environment, a subset of which looks particularly at the role of the environment for women. These qualitative interviews cited physical features, such as hills, a continuous loop, and trails, but safety was a concern due to traffic or wooded areas. The park provided support for bodily needs, such as rest rooms and freedom to wear comfortable clothes. Nature was described as stimulating the senses and restoring mental capacities, and the park was an important nearby outdoor resource. Results are discussed in the context of current research, in relation to women but also more broadly in relation to research on physical activity and the outdoor environment.

High-intensity resistance training and postmenopausal bone loss: a meta-analysis

INTRODUCTION

Conflicting evidence exists regarding the optimum exercise for postmenopausal bone loss. A systematic review and meta-analysis was undertaken to evaluate the effects of randomised controlled trials (RCTs) of progressive, high-intensity resistance training on bone mineral density (BMD) amongst postmenopausal women.

METHODS

Structured electronic searching of multiple databases and hand-searching of key journals and reference lists was undertaken to locate relevant studies up to December 2004. Study quality and possible publication bias were assessed using recognised methods. Primary outcomes were absolute changes in BMD at the lumbar spine (LS), femoral neck (FN) and total hip (TH). A priori defined subgroup analyses included concurrent hormonal or antiresorptive therapy or calcium supplementation during the intervention. The weighted mean difference method (WMD) was used for combining study group estimates. Random or fixed effect models were applied according to study heterogeneity observed from the I (2) statistic.

RESULTS

At the LS, 14 RCT study groups were homogenous (I (2)=25.2%) in demonstrating a significant increase (P=0.006) in BMD of 0.006 g/cm(2) (fixed effect; 95% CI 0.002-0.011) following high-intensity resistance training. In contrast, marked heterogeneity (I (2)=88.2%) was apparent within 11 RCT study groups evaluating FN. For this comparison, a random effects model showed a positive change in FN BMD of 0.010 g/cm(2) (95% CI -0.002 to 0.021; P = 0.11). Subgroup analyses showed more anatomical variability of BMD responses to resistance training according to participants' hormone therapy use. Treatment effects for study groups increasing all participants' calcium intake showed significant positive BMD changes at TH (P=0.007). Methodological quality of all included studies was low, and a reporting bias towards studies with positive BMD outcomes was evident.

CONCLUSIONS

These findings are relevant to the nonpharmacological treatment of postmenopausal bone loss.

The effect of vigorous physical activity and risk of wrist fracture over 25 years in a low-risk survivor cohort

Recent studies have suggested that a high level of recent physical activity increases the risk of a wrist fracture in postmenopausal women. The relationship of more distant past physical activity to wrist fracture is less clear, and most studies have relied on recall of physical activity much earlier in life. The aim of this study was to assess the risk of wrist fracture in a subset of women who had completed a recent questionnaire and also had participated in a cohort study 25 years earlier, 1865 women who were perimenopausal and postmenopausal in 1976 and had completed the 1976 and 2002 Adventist Health Study lifestyle questionnaires. Data on risk factors including physical activity were collected from the 1976 survey. Subjects reported wrist fractures occurring since baseline, and the approximate time of fracture, in the 2002 questionnaire. Incidence of wrist fracture was 3.7/1000 person-years of follow up. There was a dose-response inverse relationship between level of physical activity and wrist fracture with a 37% reduction of risk for the highest level of physical activity with respect to the lowest level (HR, 0.63; 95% CI, 0.45, 0.89). The effect of physical activity changed little in the final multivariable model (HR, 0.61; 95% CI, 0.43, 0.87). In this cohort of women with a relatively low incidence of wrist fracture, higher levels of physical activity at baseline were protective against risk of fracture during 25 years of follow-up.