Long-term effect of exercise on bone mineral density and body composition in post-menopausal ex-elite athletes: a retrospective study

Changes in the concentration of bone turnover markers in men after maximum intensity exercise

Background

Physical activity is an important factor in modelling the remodelling and metabolism of bone tissue. The aim of the study was to evaluate the changes in indices demonstrating bone turnover in men under the influence of maximum-intensity exercise.

Methods

The study involved 33 men aged 20-25, divided into two groups: experimental (n = 15) and control (n = 18). People training medium- and long-distance running were assigned to the experimental group, and non-training individuals to the control. Selected somatic, physiological and biochemical indices were measured. The level of aerobic fitness was determined using a progressively increasing graded test (treadmill test for subjective fatigue). Blood samples for determinations were taken before the test and 60 minutes after its completion. The concentration of selected bone turnover markers was assessed: bone fraction of alkaline phosphatase (b-ALP), osteoclacin (OC), N-terminal cross-linked telopeptide of the alpha chain of type I collagen (NTx1), N-terminal propeptide of type I progolagen (PINP), osteoprotegerin (OPG). In addition, the concentration of 25(OH)D3 prior to the stress test was determined. Additionally, pre and post exercise, the concentration of lactates in the capillary blood was determined.

Results

When comparing the two groups, significant statistical differences were found for the mean level of: 25(OH)D3 (p = 0.025), b-ALP (p < 0.001), OC (p = 0.004) and PINP (p = 0.029) prior to the test. On the other hand, within individual groups, between the values pre and post the stress test, there were statistically significant differences for the average level of: b-ALP (p < 0.001), NTx1 (p < 0.001), OPG (p = 0.001) and PINP (p = 0.002).

Conclusion

A single-session maximum physical effort can become an effective tool to initiate positive changes in bone turnover markers.

The effect of regular running on the bone tissue of middle-aged men and women

BACKGROUND

Many authors consider running to be a protective physical activity (PA) in bone health. However, many studies also show inconsistencies in their results. The objective of the study is to analyze the effect of cumulative loading rate (TCL) on the bone mass of middle-aged runners and non-runners is assessed.

METHODS

This cross-sectional study included 322 individuals. There were 212 runners (109 male, 103 female) and those were individuals who did >10 km of running per week. There were 110 non-runners (54 male, 56 female). This group included individuals who did not adhere to the WHO (2020) recommendations for PA. The average age in the individual groups ranged from 40.9±4.1 to 42.3±4.8 years. Bone parameters were measured on the lower extremities and vertebral spine using the DXA method (Hologic QDR Horizon A). Multi-regression dependencies analysis was used to assess the results.

RESULTS

The results of the multi-regression dependencies analysis showed that the bone mineral content (BMC) and bone mineral density (BMD) are significantly influenced by the TCL and gender.

CONCLUSIONS

Therefore, we can conclude that running could be a suitable PA for preventing the reduction of BMD in the middle-aged population, especially in the lower limbs.

Spine, hip, and femoral neck bone mineral density in relation to vegetarian type and status among Taiwanese adults

We determined the association of vegetarian type and status with bone mineral density (BMD) Z-scores at the spine, hip, and femoral neck. Compared to non-vegetarians, current vegetarians, especially vegans, lacto-vegetarians, and lacto-ovo-vegetarians had lower Z-scores at multiple sites. Sole reliance on a vegetarian diet might be detrimental to the bone.

PURPOSE

The impact of vegetarian diets on BMD is contentious. We determined the association of vegetarian type and status with the spine, hip, and femoral neck BMD Z-scores.

METHODS

We analyzed data from 20,110 Taiwan Biobank volunteers. BMD was measured using dual-energy X-ray absorptiometry (DXA). The vegetarian status (non-, former, and current vegetarians) and type (non-vegetarians, ovo-vegetarians, lacto-vegetarians, lacto-ovo-vegetarians, and vegans) were determined using questionnaires.

RESULTS

The participants consisted of 12,910 women and 7200 men, with a mean age of 55.5 years. Based on vegetarian status (reference: non-vegetarians), current vegetarians had significantly lower BMD Z-scores at the spine (unstandardized regression coefficient, B =  - 0.195, p = 0.006), left hip (B =  - 0.125, p = 0.008), and right hip (B =  - 0.100, p = 0.027), respectively. Based on vegetarian status and type (reference: non-vegetarians), current vegans and non-vegans had notably lower BMD Z-scores at specific skeletal sites. For non-vegans, the BMD Z-scores were significant at the spine (B = -0.184, p = 0.010), left hip (B =  - 0.124, p = 0.010), and left femoral neck (B =  - 0.125, p = 0.012). For current vegans, however, the BMD Z-scores were significant only at the right hip (B =  - 0.232; p = 0.028). Nonetheless, after stratifying vegetarian diet into more subgroups, current vegans exhibited a significant reduction in BMD Z-scores at the spine and right hip, with B-coefficients of - 0.326 and - 0.238, respectively. Current lacto-vegetarians also had significantly lower Z-scores (p < 0.05) at the spine (B =  - 0.459), left hip (B =  - 0.313), and right hip (B =  - 0.214). Moreover, current lacto-ovo-vegetarians had significantly lower Z-scores at the spine (B =  - 0.175) and left hip (B =  - 0.115).

CONCLUSION

Current vegetarians, particularly vegans, lacto-vegetarians, and lacto-ovo-vegetarians, demonstrated significantly lower BMD Z-scores at various skeletal sites compared to non-vegetarians. Sole reliance on a vegetarian diet might be detrimental to the bone.

Long-term function, body composition and cardiometabolic health in midlife former athletes: a scoping review

While sports medicine has traditionally focused on recovering from injury and returning athletes to sport safely after injury, there is a growing interest in the long-term health of athletes. The purpose of this scoping review was to (1) summarise the literature (methodologies and findings) on physical function, body composition and cardiometabolic health in midlife (age 40-65 years) former competitive athletes compared with non-athlete controls, (2) identify areas for future study in long-term health in athletes and (3) determine outcomes that could be evaluated in a future systematic review(s). We searched PubMed, CINAHL, Web of Science and SPORTDiscus for studies published between 2000 and 2022 evaluating former athletes and controls on physical function, body composition and/or cardiometabolic measures using MeSH terms. We identified 20 articles that met our criteria. Outcomes varied considerably across studies, most of which were cross-sectional and evaluated only males. Limited data suggest that former endurance athletes have leaner body compositions, higher aerobic capacity and better cardiometabolic indicators than controls; former athletes who maintain higher physical activity (ie, self-reported exercise) are healthier than those who do not; and former team sport athletes, who have higher injury prevalence, may have poorer functional performance than controls who were recreationally active in college. Studies rarely evaluated functional performance, did not control for prior injury or diet and seldom assessed current physical activity levels. Future research should include females and evaluate sex differences, control for prior sports-related injury(ies), quantify physical activity, use standardised outcome measures including performance-based functional assessments and incorporate longitudinal designs.

Prevalence of Female and Male Athlete Triad Risk Factors in Ultramarathon Runners

OBJECTIVE

To identify the prevalence of male and female athlete triad risk factors in ultramarathon runners and explore associations between sex hormones and bone mineral density (BMD).

DESIGN

Multiyear cross-sectional study.

SETTING

One hundred-mile ultramarathon.

PARTICIPANTS

Competing runners were recruited in 2018 and 2019.

ASSESSMENT OF RISK FACTORS

Participants completed a survey assessing eating behaviors, menstrual history, and injury history; dual-energy x-ray absorptiometry for BMD; and laboratory evaluation of sex hormones, vitamin D, and ferritin (2019 cohort only).

MAIN OUTCOME MEASURE

A Triad Cumulative Risk Assessment Score was calculated for each participant.

RESULTS

One hundred twenty-three runners participated (83 males and 40 females, mean age 46.2 and 41.8 years, respectively). 44.5% of men and 62.5% of women had elevated risk for disordered eating. 37.5% of women reported a history of bone stress injury (BSI) and 16.7% had BMD Z scores <-1.0. 20.5% of men had a history of BSI and 30.1% had Z-scores <-1.0. Low body mass index (BMI) (<18.5 kg/m 2 ) was seen in 15% of women and no men. The Triad Cumulative Risk Assessment classified 61.1% of women and 29.2% of men as moderate risk and 5.6% of both men and women as high risk.

CONCLUSIONS

Our study is the first to measure BMD in both male and female ultramarathon runners. Our male population had a higher prevalence of low BMD than the general population; females were more likely to report history of BSI. Risk of disordered eating was elevated among our participants but was not associated with either low BMD or low BMI.

The Effects of 8-Week Resistance and Endurance Trainings on Bone Strength Compared to Irisin Injection Protocol in Mice

Background

Osteoporosis is a prevalent elderly complication that is characterized by decreased bone mineral density and increased fracture risk because of dysregulation in bone mineralization and resorption. Physical activity can enhance bone strength by exerting mechanical forces and myokines. Irisin is a myokine that is increased following physical exercise and can affect bones. In this study, 8 weeks of resistance and endurance exercises are applied in mice compared to irisin injection to assess the contribution of the protocols and this myokine to bone strength.

Materials and Methods

Thirty-five male NMRI mice were separated into five groups; control, placebo, irisin injection, resistance exercise, and endurance exercise. 8-week of exercise protocols and irisin injection protocol (100 μg/kg/week) was applied. Plasma irisin concentration and bone strength were measured using enzyme-linked immunoassay and 3-point bending assay, respectively. Statistical analyses were done through one-way ANOVA and Tukey test, and P < 0.05 was considered the significant difference.

Results

Serum irisin concentration and bone strength in resistance exercise and irisin-injected groups were significantly higher than control and placebo groups (P < 0.0001). Serum irisin concentration, but not bone strength, of the endurance exercise group was also significantly higher than control and placebo groups (P < 0.0001) but lower than resistance and irisin-injected groups.

Conclusion

Resistance exercise and irisin injection, but not endurance exercise, are likely to be effective in increasing bone strength. There may be a threshold for plasma irisin level to affect bones which the applied protocols of irisin injection and resistance exercise but not endurance exercise can reach.

Jumping rope and whole-body vibration program effects on bone values in Olympic artistic swimmers

INTRODUCTION

Artistic swimming seems not to benefit bone development like other out-of-water physical activities. To increase bone acquisition, artistic swimming should combine water training with weight-bearing impact or strength activities. Artistic swimmers can be a population at risk of developing osteopenia and osteoporosis in later life. The aim of the present study was to evaluate the effects of a training program on bone mineral density (BMD), bone mineral content (BMC) and body composition in an Olympic artistic swimming team.

METHODS

Sixteen women aged 17-21 years, who train 30 h/week, at the Olympic Training Centre (Barcelona, Spain), were followed up over two seasons. The 1st season involved regular artistic swimming training without specific training to reduce the risk of osteopenia. The exercise intervention, jumping rope and whole-body vibration, was added in the 2nd season. The protocol included 20 min of training 2 days per week, over a 22-week period. Dual energy x-ray absorptiometry measured the bone variables and body composition. The daily diet, medical history and bone turnover markers were evaluated.

RESULTS

The intervention program increased BMD on lumbar spine (2.10%, p = 0.002), total hip (2.07%, p = 0.001), and femoral neck (2.39%, p = 0.02). Lower limb's fat mass decreased (10.17%, p = 0.038). No significant differences were found for any of the measured anthropometric characteristics between both time points in the 1st season. In conclusions, combined jump rope and vibration should be considered to reduce the risk of bone damage in artistic swimmers.

Bone Mineral Density Differences Across Female Olympic Lifters, Power Lifters, and Soccer Players

ABSTRACT

Jeon, W, Harrison, JM, Stanforth, PR, and Griffin, L. Bone mineral density differences across female Olympic lifters, power lifters, and soccer players. J Strength Cond Res 35(3): 638-643, 2021-Athletic training improves bone mineral density (BMD) through repeated mechanical loading. The location, intensity, and direction of applied mechanical pressure play an important role in determining BMD, making some sports more advantageous at improving BMD at specific regions. Thirty-seven (10 power lifters [PL], 8 Olympic lifters [OL], 8 soccer players [SP], and 11 recreationally active [RA]) women participated in a cross-sectional study. We measured lumbar spine (L1-L4), femoral neck, total-body BMD, and overall body composition (total fat mass, lean mass, percent body fat) with dual-energy x-ray absorptiometry. All athletic groups had greater total BMD than RA (p = 0.01 [PL]; p < 0.001 [OL]; p = 0.01 [SP]). Olympic lifters had the highest total BMD than all other athletic groups. Olympic lifters had the significantly greater total BMD than PL (p = 0.018), but there was no difference in total BMD between PL and SP. As compared with RA, OL showed greater BMD at both the total lumbar spine (p = 0.002) and the femoral neck (p = 0.007), whereas PL showed greater BMD only for the total lumbar spine (p = 0.019) and SP showed greater BMD only for the femoral neck (p = 0.002). Olympic-style lifting includes both high-impact and odd-impact loading modalities that are associated with the highest BMD at both the lumbar spine and femoral neck.

Regulation of Osteoclast Differentiation and Activity by Lipid Metabolism

Bone is a dynamic tissue and is constantly being remodeled by bone cells. Metabolic reprogramming plays a critical role in the activation of these bone cells and skeletal metabolism, which fulfills the energy demand for bone remodeling. Among various metabolic pathways, the importance of lipid metabolism in bone cells has long been appreciated. More recent studies also establish the link between bone loss and lipid-altering conditions—such as atherosclerotic vascular disease, hyperlipidemia, and obesity—and uncover the detrimental effect of fat accumulation on skeletal homeostasis and increased risk of fracture. Targeting lipid metabolism with statin, a lipid-lowering drug, has been shown to improve bone density and quality in metabolic bone diseases. However, the molecular mechanisms of lipid-mediated regulation in osteoclasts are not completely understood. Thus, a better understanding of lipid metabolism in osteoclasts can be used to harness bone cell activity to treat pathological bone disorders. This review summarizes the recent developments of the contribution of lipid metabolism to the function and phenotype of osteoclasts.

Adolescent Sport Participation and Age at Menarche in Relation to Midlife Body Composition, Bone Mineral Density, Fitness, and Physical Activity

This study aimed to investigate the associations of competitive sport participation in adolescence and age at menarche (AAM) with body composition, femoral neck bone mineral density (BMD), physical performance, and physical activity (PA) in middle-aged women. 1098 women aged 47–55 years formed the sample of this retrospective study. Participants self-reported their PA level at age 13–16 years and AAM. The protocol also included dual-energy X-ray absorptiometry, physical performance tests, and accelerometer-measured PA. Participants were divided into three groups according to their PA level at the age of 13–16 (no exercise, regular PA, and competitive sport) and according to their AAM (≤12, 13, and ≥14 years). After adjusting for potential confounding factors, participation in competitive sport at age 13–16 was associated with higher midlife lean mass and BMD, and better physical performance compared to groups with no exercise or regular PA. Individuals with AAM ≥ 14 years had lower midlife BMI and fat mass than participants in the other AAM groups and pre- and perimenopausal women with AAM ≥ 14 years had lower BMD than those with AAM ≤ 12. The findings indicate that participation in competitive sport in adolescence is associated with healthier body composition, higher BMD, and better physical performance in midlife, but BMD might be impaired if menarche occurs late.

Basketball players possess a higher bone mineral density than matched non-athletes, swimming, soccer, and volleyball athletes: a systematic review and meta-analysis

Basketball athletes possess a higher bone mineral density (BMD) than matched non-athletes and swimming, soccer, and volleyball athletes. Differences appear to be exacerbated with continued training and competition beyond adolescence. The greater BMD in basketball athletes compared to non-athletes, swimming, and soccer athletes is more pronounced in males than females.

PURPOSE

The aim of this study was to examine differences in total and regional bone mineral density (BMD) between basketball athletes, non-athletes, and athletes competing in swimming, soccer, and volleyball, considering age and sex.

METHODS

PubMed, MEDLINE, ERIC, Google Scholar, and Science Direct were searched. Included studies consisted of basketball players and at least one group of non-athletes, swimming, soccer, or volleyball athletes. BMD data were meta-analyzed. Cohen's d effect sizes [95% confidence intervals (CI)] were interpreted as: trivial ≤ 0.20, small = 0.20-0.59, moderate = 0.60-1.19, large = 1.20-1.99, and very large ≥ 2.00.

RESULTS

Basketball athletes exhibited significantly (p < 0.05) higher BMD compared to non-athletes (small-moderate effect in total-body: d = 1.06, CI 0.55, 1.56; spine: d = 0.67, CI 0.40, 0.93; lumbar spine: d = 0.96, CI 0.57, 1.35; upper limbs: d = 0.70, CI 0.29, 1.10; lower limbs: d = 1.14, CI 0.60, 1.68; pelvis: d = 1.16, CI 0.05, 2.26; trunk: d = 1.00, CI 0.65, 1.35; and femoral neck: d = 0.57, CI 0.16, 0.99), swimming athletes (moderate-very large effect in total-body: d = 1.33, CI 0.59, 2.08; spine: d = 1.04, CI 0.60, 1.48; upper limbs: d = 1.19, CI 0.16, 2.22; lower limbs: d = 2.76, CI 1.45, 4.06; pelvis d = 1.72, CI 0.63, 2.81; and trunk: d = 1.61, CI 1.19, 2.04), soccer athletes (small effect in total-body: d = 0.58, CI 0.18, 0.97), and volleyball athletes (small effect in total-body: d = 0.32, CI 0.00, 0.65; and pelvis: d = 0.48, CI 0.07, 0.88). Differences in total and regional BMD between groups increased with age and appeared greater in males than in females.

CONCLUSION

Basketball athletes exhibit a greater BMD compared to non-athletes, as well as athletes involved in swimming, soccer, and volleyball.

Bone mineral density in old age: the influence of age at menarche, menopause status and habitual past and present physical activity

INTRODUCTION

In this study, the hypothesis that bone mineral density (BMD) of peri-, pre- and postmenopausal women is associated with the current level of habitual physical activity, as well as past physical activity, at the age of building peak bone mass, was tested.

MATERIAL AND METHODS

The study involved 500 Polish women aged 40 to 70. For the assessment of BMD and bone mineral content (BMC) the densitometry method (dual-energy X-ray absorptiometry, DXA) of the forearm bone was used. The International Physical Activity Questionnaire (IPAQ) was used to assess the present level of physical activity. The assessment of past physical activity was related to adolescence.

RESULTS

There was a significant, strong influence on the norm BMD in the distal forearm sections values in the distal forearm sections of such variables as: older age of the first menstruation (OR = 1.37; p = 0.002), sufficient present physical activity (OR = 1.57; p = 0.001), and particularly high past physical activity (OR = 6.77; p = 0.003). Significantly lower chances for the norm BMD dis were found in women with the oldest hormonal status (OR = 0.09; p < 0.001). In the proximal segment, the analogous conditions of the norm BMD, and in addition the chances for good mineralization, were increased by higher body mass index (OR = 1.11; p < 0.001). Sufficient present activity increased the chances of good forearm mineralization in the proximal part more than four times (OR = 4.2; p < 0.001), and a high level of past physical activity increased these chances several dozen times (OR = 69.9; p < 0.001).

CONCLUSIONS

Physical activity proved to be one of the most important factors determining the statistically significant correct mineralization of bone tissue of women.

Irisin as a Multifunctional Protein: Implications for Health and Certain Diseases

Sedentary life style is considered to be an independent risk factor for many disorders, including development of type 2 diabetes, obesity, immune dysfunction, asthma, and neurological or coronary heart disease. Irisin is released from myocytes during physical activity, and acts as a link between muscles and other tissues and organs. This myokine is produced as a result of proteolytic cleavage of FNDC5 protein present in the membrane of myocytes. Secretion of irisin is regulated by N-linked oligosaccharides attached to the protein molecule. The two N-glycan molecules, which constitute a significant part of the irisin glycoprotein, regulate the browning of adipocytes, which is the most important function of irisin. A receptor specific for irisin has still not been discovered. In some tissues irisin probably acts via integrins, which are widely expressed transmembrane receptors. Many studies have confirmed the multifunctional role of irisin and the beneficial effects of this molecule on body homeostasis. Irisin reduces systemic inflammation, maintains the balance between resorption and bone formation, and modulates metabolic processes and the functioning of the nervous system. It suppresses the expression and release of pro-inflammatory cytokines in obese individuals and attenuates inflammation in adipose tissue. The impact of irisin on cancer cell proliferation, migration, and invasion has also been demonstrated in numerous studies, which proves its role in carcinogenesis. Owing to these pleiotropic and beneficial properties, irisin may be a potential option to prevent and treat civilization-related diseases which are, nowadays, considered to be the major health problems in Western societies.

The Effectiveness of Physical Exercise on Bone Density in Osteoporotic Patients

Physical exercise is considered an effective means to stimulate bone osteogenesis in osteoporotic patients. The authors reviewed the current literature to define the most appropriate features of exercise for increasing bone density in osteoporotic patients. Two types emerged: (1) weight-bearing aerobic exercises, i.e., walking, stair climbing, jogging, and Tai Chi. Walking alone did not appear to improve bone mass; however it is able to limit its progressive loss. In fact, in order for the weight-bearing exercises to be effective, they must reach the mechanical intensity useful to determine an important ground reaction force. (2) Strength and resistance exercises: these are carried out with loading (lifting weights) or without (swimming, cycling). For this type of exercise to be effective a joint reaction force superior to common daily activity with sensitive muscle strengthening must be determined. These exercises appear extremely site-specific, able to increase muscle mass and BMD only in the stimulated body regions. Other suggested protocols are multicomponent exercises and whole body vibration. Multicomponent exercises consist of a combination of different methods (aerobics, strengthening, progressive resistance, balancing, and dancing) aimed at increasing or preserving bone mass. These exercises seem particularly indicated in deteriorating elderly patients, often not able to perform exercises of pure reinforcement. However, for these protocols to be effective they must always contain a proportion of strengthening and resistance exercises. Given the variability of the protocols and outcome measures, the results of these methods are difficult to quantify. Training with whole body vibration (WBV): these exercises are performed with dedicated devices, and while it seems they have effect on enhancing muscle strength, controversial findings on improvement of BMD were reported. WBV seems to provide good results, especially in improving balance and reducing the risk of falling; in this, WBV appears more efficient than simply walking. Nevertheless, contraindications typical of senility should be taken into account.

Low serum concentrations of Irisin are associated with increased risk of hip fracture in Chinese older women

OBJECTIVE

Irisin derived from muscle in response to exercise may be the molecular entity responsible for muscle wasting-osteoporosis connectivity in the elderly. The objective of the study was to determine whether serum Irisin (sIrisin) provides information on hip fracture prediction which were independent of bone mineral density (BMD) and the fracture risk assessment tool (FRAX) algorithm.

METHODS

This study enrolled 160 older women (ages, 70-90y) with minimal trauma hip fractures (MTHFs) and 160 age-matched women without fracture serving as controls. Clinical features, BMD and bone turnover markers including sIrisin levels were measured after fracture within 2 days as baseline.

RESULTS

sIrisin levels were significantly lower (361.5±140.0ng/mL vs 478.5±159.6ng/mL, P<0.001) in cases than controls. After multivariate analysis, sIrisin remained as an independent variable of BMD, which explained 17.8% of femoral neck BMD and 22.5% of lumbar spine BMD, respectively. The odds ratio (OR) of MTHFs comparing the lowest (<320.1ng/mL) to highest (>524.5ng/mL) quartiles was 1.95 (95% CI 1.23-3.79, P<0.05) for sIrisin. Adjustment for age, body mass index, time since menopause and exercise ≥30min/day yielded similar results, and BMD of femoral neck also did not change these associations. Taking FRAX score into account attenuated the association somewhat: OR of hip fracture was 1.81 (95% CI 1.26-3.49, P<0.05) in first versus fourth quartile of sIrisin. There was a negative gradient of risk by decreasing quartile in sIrisin.

CONCLUSIONS

Low concentrations of sIrisin in older women were independently associated with increased risk of hip fractures when adjusted for BMD or FRAX score.

Prolonged Practice of Swimming Is Negatively Related to Bone Mineral Density Gains in Adolescents

BACKGROUND

The practice of swimming in "hypogravity" conditions has potential to decrease bone formation because it decreases the time engaged in weight-bearing activities usually observed in the daily activities of adolescents. Therefore, adolescents competing in national levels would be more exposed to these deleterious effects, because they are engaged in long routines of training during most part of the year. To analyze the effect of swimming on bone mineral density (BMD) gain among adolescents engaged in national level competitions during a 9-month period.

METHODS

Fifty-five adolescents; the control group contained 29 adolescents and the swimming group was composed of 26 athletes. During the cohort study, BMD, body fat (BF) and fat free mass (FFM) were assessed using a dual-energy x-ray absorptiometry scanner. Body weight was measured with an electronic scale, and height was assessed using a stadiometer.

RESULTS

During the follow-up, swimmers presented higher gains in FFM (Control 2.35 kg vs. Swimming 5.14 kg; large effect size [eta-squared (ES-r)=0.168]) and BMD-Spine (Swimming 0.087 g/cm(2) vs. Control 0.049 g/cm(2); large effect size [ES-r=0.167]) compared to control group. Male swimmers gained more FFM (Male 10.63% vs. Female 3.39%) and BMD-Spine (Male 8.47% vs. Female 4.32%) than females. Longer participation in swimming negatively affected gains in upper limbs among males (r=-0.438 [-0.693 to -0.085]), and in spine among females (r=-0.651 [-0.908 to -0.036]).

CONCLUSIONS

Over a 9-month follow-up, BMD and FFM gains were more evident in male swimmers, while longer engagement in swimming negatively affected BMD gains, independently of sex.

Swimming and cycling do not cause positive effects on bone mineral density: a systematic review

Osteoporosis is considered a common metabolic bone disease and its prevalence is increasing worldwide. In this context, physical activity has been used as a non-pharmacological tool for prevention and auxiliary treatment of this disease. The aim of this systematic review was to evaluate the effects of cycling and swimming practice on bone mineral density (BMD). This research was conducted in accordance with the recommendations outlined by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. The studies were consulted in the period from 2004 to 2014, through major electronic databases: PubMed(®), SciELO(®) and LILACS(®). Ten studies evaluated the effects of cycling on BMD, and the results showed that nine studies have linked the practice of professional cycling with low levels of BMD. Another 18 studies have reported that swimming has no positive effects on bone mass. We conclude that cycling and swimming do not cause positive effects on BMD; thus, these are not the most suitable exercises for prevention and treatment of osteoporosis.

Swimming and cycling do not cause positive effects on bone mineral density: a systematic review

Osteoporosis is considered a common metabolic bone disease and its prevalence is increasing worldwide. In this context, physical activity has been used as a non-pharmacological tool for prevention and auxiliary treatment of this disease. The aim of this systematic review was to evaluate the effects of cycling and swimming practice on bone mineral density (BMD). This research was conducted in accordance with the recommendations outlined by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. The studies were consulted in the period from 2004 to 2014, through major electronic databases: PubMed®, SciELO® and LILACS®. Ten studies evaluated the effects of cycling on BMD, and the results showed that nine studies have linked the practice of professional cycling with low levels of BMD. Another 18 studies have reported that swimming has no positive effects on bone mass. We conclude that cycling and swimming do not cause positive effects on BMD; thus, these are not the most suitable exercises for prevention and treatment of osteoporosis.

Role of Irisin on the bone-muscle functional unit

Irisin was originally recognized as a hormone-like myokine secreted as a product of fibronectin type III domain containing 5 from skeletal muscle in response to exercise both in mice and humans. The first role attributed to Irisin was its ability to induce trans-differentiation of white adipose tissue into brown, but we recently demonstrated that Irisin also has a central role in the control of bone mass, even at lower concentration than required to induce the browning response. Considering how physical exercise is important for the development of an efficient load-bearing skeleton, we can now consider this myokine as one of the molecules responsible for the positive correlation between exercise and healthy bone, linking to the well-established relationship between muscle and bone. Recombinant Irisin (r-Irisin), administered at low dose in young mice, increases cortical bone mineral density and positively modifies bone geometry. Irisin exerts its effect prevalently on osteoblast lineage by enhancing differentiation and activity of bone-forming cells, through the increase in activating transcription factor 4 expression. Low-dose r-Irisin also increases osteopontin and decreases sclerostin synthesis but did not affect Uncoupling protein 1 expression in white adipose tissue, whose upregulation is known to cause browning of fat, when Irisin is administered at a higher dose. These findings offer an explanation to the positive outcome on the skeleton triggered by skeletal muscle during physical activity and prove that the bone tissue is more sensitive than the adipose tissue to the Irisin action.

Facile preparation of biphasic-induced magnetic icariin-loaded composite microcapsules by automated in situ click technology

This research aims to prepare the biphasic-induced magnetic composite microcapsules (BIMCM) as a promising environmental stimuli-responsive delivery vehicle to dispose the problem of drug burst effect. The paper presented a novel automated in situ click technology of magnetic chitosan/nano hydroxyapatite (CS/nHA) microcapsules. Fe3O4 magnetic nanoparticles (MNP) and nHA were simultaneously in situ crystallized by one-step process. Icariin (ICA), a plant-derived flavonol glycoside, was combined to study drug release properties of BIMCM. BIMCM were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and Thermal gravimetric analysis/Differential Scanning Calorimetry(TGA/DSC) in order to reveal their component and surface morphology as well as the role of the in situ generated Fe3O4 MNP and nHA. The magnetic test showed the BIMCM were super-paramagnetic. Both in situ generated Fe3O4 MNP and nHA serve as stable inorganic crosslinkers in BIMCM to form many intermolecular crosslinkages for the movability of the CS chains. This makes ICA loaded microcapsules take on a sustained release behavior and results in the self-adjusting of surface morphology, decreasing of swelling and degradation rates. In addition, in vitro tests were systematically carried out to examine the biocompatibility of the microcapsules by MTT test, Wright-Giemsa dying assay and AO/EB fluorescent staining method. These results demonstrated that successful introduction of the in situ click Fe3O4 MNP provided an alternative strategy because of magnetic sensitivity and sustained release. As such, the novel ICA loaded biphasic-induced magnetic CS/nHA/MNP microcapsules are expected to find potential applications in drug delivery system for bone repair.

Relationship between Bone Mineral Density and Spinal Muscle Area in Magnetic Resonance Imaging

Background

Bone mineral density (BMD) is known to have a positive correlation with lean body mass. Several studies have also reported the positive correlation between muscle power and BMD. From this point of view, we hypothesized BMD of lumbar spine to have a positive correlation with muscle mass.

Methods

Seventy-nine female patients aged between 60 and 75 years old and who underwent magnetic resonance imaging (MRI) and BMD studies were included. Muscle mass in spine MRI was defined by the sum of the average muscle area of three axial images for each disc level. Lumbosacral muscle is the sum of paraspinal muscle and psoas muscle.

Results

In correlation analysis, paraspinal muscle mass showed positive correlation with BMD of lumbar spine. Lumbosacral muscle mass showed positive correlation with BMD of trochanteric area of the femur. However, BMD of other area showed no significant correlation with muscle mass.

Conclusions

Therefore, postmenopausal women older than 60 years with a well developed spine muscle mass, have a high BMD.

The myokine irisin increases cortical bone mass

It is unclear how physical activity stimulates new bone synthesis. We explored whether irisin, a newly discovered myokine released upon physical activity, displays anabolic actions on the skeleton. Young male mice were injected with vehicle or recombinant irisin (r-irisin) at a low cumulative weekly dose of 100 µg kg(-1). We observed significant increases in cortical bone mass and strength, notably in cortical tissue mineral density, periosteal circumference, polar moment of inertia, and bending strength. This anabolic action was mediated primarily through the stimulation of bone formation, but with parallel notable reductions in osteoclast numbers. The trabecular compartment of the same bones was spared, as were vertebrae from the same mice. Higher irisin doses (3,500 µg kg(-1) per week) cause browning of adipose tissue; this was not seen with low-dose r-irisin. Expectedly, low-dose r-irisin modulated the skeletal genes, Opn and Sost, but not Ucp1 or Pparγ expression in white adipose tissue. In bone marrow stromal cell cultures, r-irisin rapidly phosphorylated Erk, and up-regulated Atf4, Runx2, Osx, Lrp5, β-catenin, Alp, and Col1a1; this is consistent with a direct receptor-mediated action to stimulate osteogenesis. We also noted that, although the irisin precursor Fndc5 was expressed abundantly in skeletal muscle, other sites, such as bone and brain, also expressed Fndc5, albeit at low levels. Furthermore, muscle fibers from r-irisin-injected mice displayed enhanced Fndc5 positivity, and irisin induced Fdnc5 mRNA expression in cultured myoblasts. Our data therefore highlight a previously unknown action of the myokine irisin, which may be the molecular entity responsible for muscle-bone connectivity.

Effect of a program of short bouts of exercise on bone health in adolescents involved in different sports: the PRO-BONE study protocol

BACKGROUND

Osteoporosis is a skeletal disease associated with high morbidity, mortality and increased economic costs. Early prevention during adolescence appears to be one of the most beneficial practices. Exercise is an effective approach for developing bone mass during puberty, but some sports may have a positive or negative impact on bone mass accrual. Plyometric jump training has been suggested as a type of exercise that can augment bone, but its effects on adolescent bone mass have not been rigorously assessed. The aims of the PRO-BONE study are to: 1) longitudinally assess bone health and its metabolism in adolescents engaged in osteogenic (football), non-osteogenic (cycling and swimming) sports and in a control group, and 2) examine the effect of a 9 month plyometric jump training programme on bone related outcomes in the sport groups.

METHODS/DESIGN

This study will recruit 105 males aged 12-14 years who have participated in sport specific training for at least 3 hours per week during the last 3 years in the following sports groups: football (n = 30), cycling (n = 30) and swimming (n = 30). An age-matched control group (n = 15) that does not engage in these sports more than 3 hours per week will also be recruited. Participants will be measured on 5 occasions: 1) at baseline; 2) after 12 months of sport specific training where each sport group will be randomly allocated into two sub-groups: intervention group (sport + plyometric jump training) and sport group (sport only); 3) exactly after the 9 months of intervention; 4) 6 months following the intervention; 5) 12 months following the intervention. Body composition (dual energy X-ray absorptiometry, air displacement plethysmography and bioelectrical impedance), bone stiffness index (ultrasounds), physical activity (accelerometers), diet (24 h recall questionnaire), pubertal maturation (Tanner stage), physical fitness (cardiorespiratory and muscular), bone turnover markers and vitamin D will be measured at each visit.

DISCUSSION

The PRO-BONE study is designed to investigate the impact of osteogenic and non-osteogenic sports on bone development in adolescent males during puberty, and how a plyometric jump training programme is associated with body composition parameters.

Work- and travel-related physical activity and alcohol consumption: relationship with bone mineral density and calcaneal quantitative ultrasonometry

A number of healthy workers rarely exercise because of a lack of time or resources. Physical activity related to work and everyday travel may be more feasible, but evidence of its beneficial effect on bone health is scarce. We assessed if this form of physical activity was associated with higher bone mineral density (BMD) and stiffness index (SI) when adjusted for recreational physical activity, age, body mass index, smoking, alcohol consumption, education, and serum level of 25-hydroxyvitamin D. Healthy workers, aged 25-54 yr, of the Electricity Generating Authority of Thailand were surveyed. The outcomes were BMD (lumbar spine, femoral neck, and total hip) and calcaneal SI. Physical activity was estimated using the global physical activity questionnaire and considered active when >600 metabolic equivalent tasks (min). Of 2268 subjects, 74% were men. Active male subjects had significantly higher BMD at the femoral neck and total hip (p<0.005). However, the association was not significant with male lumbar spine BMD, male SI, or any bone parameters in women (p>0.05). In men, work and travel physical activity seems beneficial to male bone health; hence, it should be encouraged. Furthermore, smoking appeared harmful while moderate alcohol consumption was beneficial.

Is bone tissue really affected by swimming? A systematic review

Background

Swimming, a sport practiced in hypogravity, has sometimes been associated with decreased bone mass.

Aim

This systematic review aims to summarize and update present knowledge about the effects of swimming on bone mass, structure and metabolism in order to ascertain the effects of this sport on bone tissue.

Methods

A literature search was conducted up to April 2013. A total of 64 studies focusing on swimmers bone mass, structure and metabolism met the inclusion criteria and were included in the review.

Results

It has been generally observed that swimmers present lower bone mineral density than athletes who practise high impact sports and similar values when compared to sedentary controls. However, swimmers have a higher bone turnover than controls resulting in a different structure which in turn results in higher resistance to fracture indexes. Nevertheless, swimming may become highly beneficial regarding bone mass in later stages of life.

Conclusion

Swimming does not seem to negatively affect bone mass, although it may not be one of the best sports to be practised in order to increase this parameter, due to the hypogravity and lack of impact characteristic of this sport. Most of the studies included in this review showed similar bone mineral density values in swimmers and sedentary controls. However, swimmers present a higher bone turnover than sedentary controls that may result in a stronger structure and consequently in a stronger bone.

Changes in physical activity and body composition in postmenopausal women over time

PURPOSE

Higher physical activity (PA) has been associated with greater attenuation of body fat gain and preservation of lean mass across the lifespan. These analyses aimed to determine relationships of change in PA to changes in fat and lean body mass in a longitudinal prospective study of postmenopausal women.

METHODS

Among 11,491 women enrolled at three Women's Health Initiative clinical centers who were selected to undergo dual-energy x-ray absorptiometry, 8352 had baseline body composition measurements, with at least one repeated measure at years 1, 3, and 6. PA data were obtained by self-report at baseline and 3 and 6 yr of follow-up. Time-varying PA effect on change in lean and fat mass during the 6-yr study period for age groups (50-59 yr, 60-69 yr, and 70-79 yr) was estimated using mixed effects linear regression.

RESULTS

Baseline PA and body composition differed significantly among the three age groups. The association of change in fat mass from baseline and time-varying PA differed across the three age groups (P = 0.0006). In women age 50-59 yr, gain in fat mass from baseline was attenuated with higher levels of PA. Women age 70-79 yr lost fat mass at all PA levels. In contrast, change in lean mass from baseline and time-varying PA did not differ by age group (P = 0.1935).

CONCLUSIONS

The association between PA and change in fat mass varies by age group, with younger, but not older, women benefiting from higher levels of aerobic PA. Higher levels of aerobic activity are not associated with changes in lean mass, which tends to decrease in older women regardless of activity level. Greater attention to resistance training exercises may be needed to prevent lean mass loss as women age.

Differential features of muscle fiber atrophy in osteoporosis and osteoarthritis

We demonstrated that osteoporosis is associated with a preferential type II muscle fiber atrophy, which correlates with bone mineral density and reduced levels of Akt, a major regulator of muscle mass. In osteoarthritis, muscle atrophy is of lower extent and related to disease duration and severity.

INTRODUCTION

Osteoarthritis (OA) and osteoporosis (OP) are associated with loss of muscle bulk and power. In these diseases, morphological studies on muscle tissue are lacking, and the underlying mechanisms of muscle atrophy are not known. The aim of our study was to evaluate the OP- or OA-related muscle atrophy and its correlation with severity of disease. Muscle levels of Akt protein, a component of IGF-1/PI3K/Akt pathway, the main regulator of muscle mass, have been determined.

METHODS

We performed muscle biopsy in 15 women with OP and in 15 women with OA (age range, 60-85 years). Muscle fibers were counted, measured, and classified by ATPase reaction. By statistical analysis, fiber-type atrophy was correlated with bone mineral density (BMD) in the OP group and with Harris Hip Score (HHS) and disease duration in the OA group. Akt protein levels were evaluated by Western blot analysis.

RESULTS

Our findings revealed in OP a preferential type II fiber atrophy that inversely correlated with patients' BMD. In OA, muscle atrophy was of lower extent, homogeneous among fiber types and related to disease duration and HHS. Moreover, in OP muscle, the Akt level was significantly reduced as compared to OA muscles.

CONCLUSIONS

This study shows that in OP, there is a preferential and diffuse type II fiber atrophy, proportional to the degree of bone loss, whereas in OA, muscle atrophy is connected to the functional impairment caused by the disease. A reduction of Akt seems to be one of the mechanisms involved in OP-related muscle atrophy.

Comparison of mandibular bone mineral densities in dentate and edentulous patients

PURPOSE

In contemporary implant dentistry, bone mineral density (BMD) of the jaws is a patient-associated prognostic factor. The aim of this study was to compare the mandibular body BMD of dentate and edentulous patients using the dual-energy X-ray absorptiometry (DXA) technique.

MATERIALS AND METHODS

A total of 39 patients, 20 dentate and 19 edentulous, were included in this cross-sectional study. Mandibular body BMD was measured using the DXA technique. The variables were normally distributed; thus, the independent samples t-test was used for the determination of statistical significance between the dentate and edentulous groups (age, body mass index [BMI], DXA). Chi-square test was performed for identification of the gender differences between the groups. The Pearson correlation analysis was used to analyze the relationship between age, BMI, and mandibular body BMD. Note that p < 0.01 was accepted as the significance level.

RESULTS

There was no statistically significant difference between the dentate and edentulous groups in matching variables (age, BMI, and gender) (p > 0.01). There was a statistically significant difference regarding the mandibular body BMD in the dentate and edentulous group (p < 0.01) controlling for age, gender, and BMI. The edentulous group patients had higher mandibular body BMD values (1.27 ± 0.31 g/cm(2)) than those in the dentate group (0.94 ± 0.22 g/cm(2)).

CONCLUSION

Comparison of the mandibular body BMD revealed that dentate patients had less dense bone than the edentulous patients. Further investigations are needed to determine the BMD of the jaws in different regions and for different systemic conditions.

Total and femoral neck bone mineral density and physical activity in a sample of men and women

Physical activity (PA), total body fat (TBF), and lean body mass (LBM) are associated with bone mineral density (BMD). However, the independent influence of PA on BMD, while controlling for body composition is not understood as well and is the purpose of the current study. Whole-body BMD (g·cm⁻²), femoral neck BMD (g·cm⁻²), TBF (kg), and LBM (kg) were measured with dual-energy X-ray absorptiometry. PA levels (total, work, sport, non-sport) were estimated using the Baecke questionnaire. General linear models determined the independent effects of PA on BMD (whole-body and femoral neck), with adjustment for age, sex, ethnicity, smoking, menopausal status (as appropriate), LBM, and TBF. These associations were also examined by sex and age group (20-34, 35-49, and 50-64 years). The sample included 802 adults (65% women; 13% African American) from the Pennington Center Longitudinal Study that were 20 to 64 years of age (mean ± SD: 46.9 ± 11.0 years). Higher sports scores were associated with higher femoral neck BMD in the total group, men and women, and in 20- to 34-year-olds and 35- to 49-year-olds, but not significant in those 50-64 years of age. Similar significant associations were found for sports score with total body BMD; however, this relationship was not significant for women or for those 50-64 years of age. Total PA had inconsistent relationships with both femoral neck BMD and total body BMD. Higher levels of sport-related PA are associated with higher femoral neck BMD; however, these relationships vary by PA domain and site of BMD measurement.