The bone response to non-weight-bearing exercise is sport-, site-, and sex-specific

Does Swimming Exercise Impair Bone Health? A Systematic Review and Meta-Analysis Comparing the Evidence in Humans and Rodent Models

BACKGROUND

The effect of swimming on bone health remains unclear, namely due to discrepant findings between studies in humans and animal models.

OBJECTIVE

The aim of this systematic review and meta-analysis is to identify the available evidence on the effects of swimming on bone mass, geometry and microarchitecture at the lumbar spine, femur and tibia in both humans and rodent animal models.

METHODS

The study followed PRISMA guidelines and was registered at PROSPERO (CRD4202236347 and CRD42022363714 for human and animal studies). Two different systematic literature searches were conducted in PubMed, Scopus and Web of Science, retrieving 36 and 16 reports for humans and animal models, respectively.

RESULTS

In humans, areal bone mineral density (aBMD) was similar between swimmers and non-athletic controls at the lumbar spine, hip and femoral neck. Swimmers' tibia diaphysis showed a higher cross-sectional area but lower cortical thickness. Inconsistent findings at the femoral neck cortical thickness were found. Due to the small number of studies, trabecular microarchitecture in human swimmers was not assessed. In rodent models, aBMD was found to be lower at the tibia, but similar at the femur. Inconsistent findings in femur diaphysis cross-sectional area were observed. No differences in femur and tibia trabecular microarchitecture were found.

CONCLUSION

Swimming seems to affect bone health differently according to anatomical region. Studies in both humans and rodent models suggest that tibia cortical bone is negatively affected by swimming. There was no evidence of a negative effect of swimming on other bone regions, both in humans and animal models.

Effects of Exercise and Sports Intervention and the Involvement Level on the Mineral Health of Different Bone Sites in the Leg, Hip, and Spine: A Systematic Review and Meta-Analysis

The current study analysed whether the osteogenic stimuli of exercises and sports have an independent effect on bone mineral density (BMD). Studies with a design having two different cohorts were searched and selected to distinguish the effect due to long-term involvement (i.e., athletes vs. non-active young with good bone health) and due to the planning of intervention (i.e., pre- vs. post-training) with exercises and sports. Moreover, only studies investigating the bone sites with a body-weight support function (i.e., lower limb, hip, and spine regions) were reviewed, since the osteogenic effects have incongruous results. A meta-analysis was performed following the recommendations of PRISMA. Heterogeneity (I2) was determined by combining Cochran's Q test with the Higgins test, with a significance level of α = 0.05. The studies reporting the effect of involvement in exercise and sports showed high heterogeneity for the lower limb, total hip, and spine (I2 = 90.200%, 93.334%, and 95.168%, respectively, with p < 0.01) and the effect size on sports modalities (Hedge's g = 1.529, 1.652, and 0.417, respectively, with p < 0.05) ranging from moderate to high. In turn, the studies reporting the effect of the intervention planning showed that there was no heterogeneity for the lower limb (I2 = 0.000%, p = 0.999) and spine (I2 = 77.863%, p = 0.000); however, for the hip, it was moderate (I2 = 49.432%, p = 0.054), with a low effect between the pre- and post-training moments presented only for the hip and spine (Hedge's g = 0.313 and 0.353, respectively, with p < 0.05). The current analysis supported the effect of involvement in exercise and sports by evidencing the effect of either weight-bearing or non-weight-bearing movements on BMD at the femoral, pelvic, and lumbar bones sites of the athletes when comparing to non-athletes or non-active peers with healthy bones. Moreover, the effect of different exercise and sports interventions highlighted the alterations in the BMD in the spine bone sites, mainly with long-term protocols (~12 months) planned with a stimulus with high muscle tension. Therefore, exercise and sport (mainly systematic long-term practice) have the potential to increase the BMD of bones with body-weight support beyond the healthy values reached during life phases of youth and adulthood.

A summary of the Malaysian Clinical Practice Guidelines on the management of postmenopausal osteoporosis, 2022

Objectives

The aim of these Clinical Practice Guidelines is to provide evidence-based recommendations to assist healthcare providers in the screening, diagnosis and management of patients with postmenopausal osteoporosis (OP).

Methods

A list of key clinical questions on the assessment, diagnosis and treatment of OP was formulated. A literature search using the PubMed, Medline, Cochrane Databases of Systematic Reviews, and OVID electronic databases identified all relevant articles on OP based on the key clinical questions, from 2014 onwards, to update from the 2015 edition. The articles were graded using the SIGN50 format. For each statement, studies with the highest level of evidence were used to frame the recommendation.

Results

This article summarizes the diagnostic and treatment pathways for postmenopausal OP. Risk stratification of patients with OP encompasses clinical risk factors, bone mineral density measurements and FRAX risk estimates. Non-pharmacological measures including adequate calcium and vitamin D, regular exercise and falls prevention are recommended. Pharmacological measures depend on patients' fracture risk status. Very high-risk individuals are recommended for treatment with an anabolic agent, if available, followed by an anti-resorptive agent. Alternatively, parenteral anti-resorptive agents can be used. High-risk individuals should be treated with anti-resorptive agents. In low-risk individuals, menopausal hormone replacement or selective estrogen receptor modulators can be used, if indicated. Patients should be assessed regularly to monitor treatment response and treatment adjusted, as appropriate.

Conclusions

The pathways for the management of postmenopausal OP in Malaysia have been updated. Incorporation of fracture risk stratification can guide appropriate treatment.

The effect of the exercise environment and the level of involvement on bone mineral health

INTRODUCTION

This study aimed to compare athletes practicing exercise in different environments with non-active young and elderly men and women regarding bone mineral density (BMD), hypothesizing that BMD values differ between athletes according to the environment of exercise practice, but those training in a low-gravitational environment have no different stimuli to BMD increasing if compared with healthy peers experiencing reduced exercise involvement, whatever the age group and sex.

MATERIALS AND METHODS

104 participants of both sexes were selected according to the environment of exercise practice [swimmers (N = 26) and judo fighters (N = 26)], and exercise level of involvement [non-active young (N = 26) and older adults (N = 26)]. Dual-energy X-ray absorptiometry provided BMD, lean mass, and fat mass (FM) for the whole body (WB), upper (UL), and lower limbs (LL).

RESULTS

For the BMD in WB, UL and LL no effects of group and sex were observed (p > 0.05). Post-hoc analyses detected higher values of BMD in UL for female swimmers compared to non-active older adults (p < 0.05), while judo fighters showed higher BMD in WB, UL, and LL than other participants whatever the sex (p < 0.01). Lower FM was observed for WB, UL, and LL when swimmers and judo fighters were compared to non-active young and older female peers (p < 0.01).

CONCLUSION

The findings emphasized that BMD stimuli with swimming are reduced when compared to judo, and despite the stimuli in swimming is not distinguishable from that affecting BMD in WB, UL and LL of non-active young, it is effective in differing BMD in UL among non-active older for women.

Bone Tissue Responsiveness To Mechanical Loading-Possible Long-Term Implications of Swimming on Bone Health and Bone Development

PURPOSE OF REVIEW

To revisit the bone tissue mechanotransduction mechanisms behind the bone tissue response to mechanical loading and, within this context, explore the possible negative influence of regular swimming practice on bone health, particularly during the growth and development period.

RECENT FINDINGS

Bone is a dynamic tissue, responsive to mechanical loading and unloading, being these adaptative responses more intense during the growth and development period. Cross-sectional studies usually report a lower bone mass in swimmers compared to athletes engaged in weigh-bearing sports. However, studies with animal models show contradictory findings about the effect of swimming on bone health, highlighting the need for longitudinal studies. Due to its microgravity characteristics, swimming seems to impair bone mass, but mostly at the lower limbs. It is unkown if there is a causal relationship between swimming and low BMD or if other confounding factors, such as a natural selection whithin the sport, are the cause.

Myocytic androgen receptor overexpression does not affect sex differences in adaptation to chronic endurance exercise

Muscle-specific androgen receptor (AR) overexpression (HSAAR transgene) in sedentary male rats results in reduced adiposity, increased mitochondrial enzyme activity, and selective increase in Type 2b myofiber size. Here, we tested chronic endurance exercise interactions with this phenotype in both sexes. Across 9 weeks, rats ran 5×/week on motorized running wheels at increasing speeds and durations. Exercise reduced fat mass in all groups, but sex affected endurance exercise outcomes such that absolute lean mass increased only in females and total body mass decreased only in males. Expected sex differences were observed with males exhibiting greater total body and lean mass; absolute and relative fat mass; bone mineral density; extensor digitorum longus (EDL) myofiber size and glycolytic proportion; but lesser Type 2a and Type 1 myosin expression in tibialis anterior. Observed HSAAR outcomes were not altered by sex, with transgenic rats having greater lean mass, Type 2a myosin expression in soleus, and glycolytic myofiber size in EDL. Tibialis AR content was independently affected by sex, HSAAR, and exercise. No sex differences were observed in tibialis AR expression in wild-type rats, although HSAAR males had greater AR content than HSAAR females. We identified a moderate correlation between AR expression and glycolytic myofiber size, but not whole-body composition. Overall, results suggest myocytic AR overexpression and chronic exercise, despite sharing a similar phenotype to adaptation, are mediated by distinct mechanisms. Further, this study illustrates sex differences in adaptation to chronic endurance exercise, and suggests sex-similarity in the relationship between muscle AR and exercise response.

Adaptations in bone, lean, and total mass after forced endurance exercise are sex-dependent in rats.

Sex differences in muscle fiber-type size and proportion, lean body mass, and bone density are independent of exercise in rats.

Myocytic AR overexpression promotes lean body mass and glycolytic myofiber size in both sexes.

Skeletal muscle AR protein is elevated by chronic endurance exercise in rats, and these changes in AR content are correlated with improved glycolytic myofiber size.

Strength Training in Swimming

This narrative review deals with the topic of strength training in swimming, which has been a controversial issue for decades. It is not only about the importance for the performance at start, turn and swim speed, but also about the question of how to design a strength training program. Different approaches are discussed in the literature, with two aspects in the foreground. On the one hand is the discussion about the optimal intensity in strength training and, on the other hand, is the question of how specific strength training should be designed. In addition to a summary of the current state of research regarding the importance of strength training for swimming, the article shows which physiological adaptations should be achieved in order to be able to increase performance in the long term. Furthermore, an attempt is made to explain why some training contents seem to be rather unsuitable when it comes to increasing strength as a basis for higher performance in the start, turn and clean swimming. Practical training consequences are then derived from this. Regardless of the athlete's performance development, preventive aspects should also be considered in the discussion. The article provides a critical overview of the abovementioned key issues. The most important points when designing a strength training program for swimming are a sufficiently high-load intensity to increase maximum strength, which in turn is the basis for power, year-round strength training, parallel to swim training and working on the transfer of acquired strength skills in swim training, and not through supposedly specific strength training exercises on land or in the water.

Physical Activity Modulates miRNAs Levels and Enhances MYOD Expression in Myoblasts

Stem cells functions are regulated by different factors and non-conding RNAs, such as microRNA. MiRNAsplay an important role in modulating the expression of genes involved in the commitment and differentiation of progenitor cells. MiRNAs are post transcriptional regulators which may be modulated by physical exercise. MiRNAs, by regulating different signaling pathways, play an important role in myogenesis as well as in muscle activity. MiRNAs quantification may be considered for evaluating physical performance or muscle recovery. With the aim to identify specific miRNAs potentially involved in myogenesis and modulated by physical activity, we investigated miRNAs expression following physical performance in Peripheral Blood Mononuclear Cells (PBMCs) and in sera of half marathon (HM) runnners. The effect of runners sera on Myogenesis in in vitro cellular models was also explored. Therefore, we performed Microarray Analysis and Real Time PCR assays, as well as in vitro cell cultures analysis to investigate myogenic differentiation. Our data demonstrated gender-specific expression patterns of PBMC miRNAs before physical performance. In particular, miR223-3p, miR26b-5p, miR150-5p and miR15-5p expression was higher, while miR7a-5p and miR7i-5p expression was lower in females compared to males. After HM, miR152-3p, miR143-3p, miR27a-3p levels increased while miR30b-3p decreased in both females and males: circulating miRNAs mirrored these modulations. Furthermore, we also observed that the addition of post-HM participants sera to cell cultures exerted a positive effect in stimulating myogenesis. In conclusion, our data suggest that physical activity induces the modulation of myogenesis-associated miRNAs in bothfemales and males, despite the gender-associated different expression of certain miRNAs, Noteworthy, these findings might be useful for evaluating potential targets for microRNA based-therapies in diseases affecting the myogenic stem cells population.

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.

Sex differences in the patterning of age-related bone loss in the human hallucal metatarsal in rural and urban populations

OBJECTIVES

Age-degenerative features of the metatarsals are poorly known despite the importance of metatarsal bone properties for investigating mobility patterns. We assessed the role of habitual activity in shaping the patterning and magnitude of sexual dimorphism in age-related bone loss in the hallucal metatarsal.

MATERIALS AND METHODS

Cross-sections were extracted at midshaft from micro-computed tomography scan models of individuals from medieval rural (Abingdon Vineyard) and early industrial urban (Spitalfields) settings (n = 71). A suite of cross-sectional geometry dimensions and biomechanical properties were compared between populations.

RESULTS

The rural group display generally stronger and larger metatarsals that show a greater capacity to resist torsion and that have comparatively greater bending strength along the medio-lateral plane. Men in both groups show greater values of cortical area than women, but only in the urban group do men show lower magnitudes of age-related decline compared to females. Women in rural and urban populations show different patterns of age-related decline in bone mass, particularly old women in the urban group show a marked decline in cortical area that is absent for women in the rural group.

DISCUSSION

Lifetime exposure to hard, physical activity in an agricultural setting has contributed to the attainment of greater bone mass and stronger bones in young adults. Furthermore, over the life-course, less of this greater amount of bone is lost, such that sustained activity levels may have acted to buffer against age-related decline, and this is most pronounced for women, who are expected to experience greater bone loss later in life than men.

Age, but not short-term intensive swimming, affects chondrocyte turnover in zebrafish vertebral cartilage

Both age and intensive exercise are generally considered critical risk factors for osteoarthritis. In this work, we intend to establish zebrafish models to assess the role of these two factors on cartilage homeostasis. We designed a swimming device for zebrafish intensive exercise. The body measurements, bone mineral density (BMD) and the histology of spinal cartilages of 4- and 12-month-old zebrafish, as well the 12-month-old zebrafish before and after a 2-week exercise were compared. Our results indicate that both age and exercise affect the body length and body weight, and the micro-computed tomography reveals that both age and exercise affect the spinal BMD. However, quantitative analysis of immunohistochemistry and histochemistry indicate that short-term intensive exercise does not affect the extracellular matrix (ECM) of spinal cartilage. On the other hand, the cartilage ECM significantly grew from 4 to 12 months of age with an increase in total chondrocytes. dUTP nick end labeling staining shows that the percentages of apoptotic cells significantly increase as the zebrafish grows, whereas the BrdU labeling shows that proliferative cells dramatically decrease from 4 to 12 months of age. A 30-day chase of BrdU labeling shows some retention of labeling in cells in 4-month-old spinal cartilage but not in cartilage from 12-month-old zebrafish. Taken together, our results suggest that zebrafish chondrocytes are actively turned over, and indicate that aging is a critical factor that alters cartilage homeostasis. Zebrafish vertebral cartilage may serve as a good model to study the maturation and homeostasis of articular cartilage.

Distance running alters peripheral microRNAs implicated in metabolism, fluid balance, and myosin regulation in a sex-specific manner

Microribonucleic acids (miRNAs) mediate adaptive responses to exercise and may serve as biomarkers of exercise intensity/capacity. Expression of miRNAs is altered in skeletal muscle, plasma, and saliva following exertion. Women display unique physiologic responses to endurance exercise, and miRNAs respond to pathologic states in sex-specific patterns. However sex-specific miRNA responses to exercise remain unexplored. This study utilized high-throughput RNA sequencing to measure changes in salivary RNA expression among 25 collegiate runners following a single long-distance run. RNA concentrations in pre- and post-run saliva was assessed through alignment and quantification of 4,694 miRNAs and 27,687 mRNAs. Pair-wise Wilcoxon rank-sum test identified miRNAs with significant [false discovery rate (FDR) < 0.05] post-run changes. Associations between miRNA levels and predicted mRNA targets were explored with Pearson correlations. Differences in miRNA patterns between men ( n = 13) and women ( n = 12) were investigated with two-way analysis of variance. Results revealed 122 salivary miRNAs with post-run changes. The eight miRNAs with the largest changes were miR-3671, miR-5095 (downregulated); and miR-7154-3p, miR-200b-5p, miR-5582-3p, miR-6859-3p, miR-6751-5p, miR-4419a (upregulated). Predicted mRNA targets for these miRNAs represented 15 physiologic processes, including glycerophospholipid metabolism (FDR = 0.042), aldosterone-regulated sodium reabsorption (FDR = 0.049), and arrhythmogenic ventricular cardiomyopathy (FDR = 0.018). Twenty-six miRNA/mRNA pairs had associated changes in post-run levels. Three miRNAs (miR-4675, miR-6745, miR-6746-3p) demonstrated sex-specific responses to exercise. Numerous salivary miRNAs change in response to endurance running and target the expression of genes involved in metabolism, fluid balance, and musculoskeletal adaptations. A subset of miRNAs may differentiate the metabolic response to exercise in men and women.

The Impact of Training Load on Bone Mineral Density of Adolescent Swimmers: A Structural Equation Modeling Approach

PURPOSE

To investigate the mediating effect of muscle mass on the relationship between training load and bone density in adolescent swimmers.

METHODS

A cross-sectional study involving 87 control and 22 swimmers aged 10-19 years (overall sample: n = 109). Swimmers had a minimum of 1 year of competition in regional and national championships, and control adolescents reported 1 year without any organized sport. Bone density was the main outcome (dual-energy X-ray absorptiometry), which was measured in upper limbs, lower limbs, spine, and whole body. Monthly training load was the independent variable, while the mediation effect of lean soft tissue was assessed. Maturity offset, age, inflammation, and vitamin D intake were treated as covariates.

RESULTS

Swimmers had lower bone density than controls; there was a significant and positive relationship between training load and muscle mass. In boys, training load presented a negative correlation with bone density in lower limbs [r = -.293; 95% confidence interval (CI), -.553 to -.034]. In girls, training load was negatively related to bone mineral density in lower limbs (r = .563; 95% CI, -.770 to -.356) and whole body (r = -.409; 95% CI, -.609 to -.209).

CONCLUSION

Training load had a negative relationship on bone density of swimmers of both sexes, independently of the positive effect of lean soft tissue on bone density.

Swimming and peak bone mineral density: A systematic review and meta-analysis

This meta-analysis aims to determine the effects of regular swimming on bone mineral density (BMD) in young adults (18-30 years). A systematic search was performed in Pubmed, SPORTDiscus and the Cochrane Library from the earliest possible year to March 2016. Swimmers were compared to non-athletic controls (CG) and to high-impact athletes (HIGH). Effect sizes with the Hedges g in random effects models were developed. Fourteen studies met the inclusion criteria and were included in the meta-analyses. Swimmers presented similar BMD values to CG in whole-body (g = -0.20; P = 0.251), femoral neck (g = -0.05; P = 0.818) and lumbar spine (g = 0.18; P = 0.492); and lower BMD in the whole-body (g = -1.21; P < 0.001), femoral neck (g = -1.51; P < 0.001) and lumbar spine (g = -0.84; P = 0.017) than the HIGH. For the whole-body differences, the higher the latitude the smaller the differences between swimmers and HIGH (B = 0.10; P = 0.001). For the femoral neck differences, age also seemed to reduce the differences between groups (B = 0.19; P = 0.020). Young adult swimmers present similar BMD values than CG and lower values than HIGH.

A review of the effect of swim training and nutrition on bone mineral density in female athletes

PURPOSE

The present paper reviews the physiological adaptation to swim training and dietary supplementation relating to bone mineral density (BMD) in female swimmers. Swim training still seems to have conflicting effects on bone health maintenance in athletes.

METHODS

This review article focuses on swim training combined with dietary supplementation with respect to BMD in female athletes.

RESULTS

Upon review of previous studies, it became obvious that the majority of studies did not collect physical activity data on the swimmers outside of their swimming activities. These activities may have some influence on the BMD of swimmers and therefore, future studies need to examine additional physical activity history data as well as swim training. This additional information may help to explain why swimmers' BMD tends to be lower than the BMD of control individuals in many studies. Moreover, dietary supplementation such as calcium, magnesium, and vitamin D also affect bone health in swimmers, and it is extremely important to evaluate BMD in the context of dietary supplementation.

CONCLUSION

A review of the literature suggests that exercise intervention studies, including longitudinal and randomized control trials, need to attempt to introduce various exercise programs to female swimmers in order to determine the optimal exercise prescription for bone health.

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.

Gluteal muscle function and size in swimmers

OBJECTIVES

To compare the gluteus medius and minimus segments size and activity in swimmers versus non-swimmers.

DESIGN

Case matched-control cross-sectional study.

METHODS

The three segments of gluteus medius (anterior, middle and posterior) and two segments of gluteus minimus (anterior and posterior) were evaluated using electromyography and magnetic resonance imaging in 15 swimmers (7 elite and 8 non-elite) and 15 gender- and aged-matched controls. For each muscle segment, values were obtained for peak amplitude, average amplitude, and time to peak from each phase of the gait cycle (0-20%, 20-60%, and total stance).

RESULTS

The pattern of anterior gluteus minimus EMG activity in swimmers demonstrated additional activity early in the gait cycle when compared with controls. The segmental differences between anterior and posterior gluteus minimus during gait identified in the control group were not present in the swimmers. Overall, there were no significant differences in the gluteus medius EMG characteristics between groups and muscle size was not significantly different between groups for any of the hip abductor muscles.

CONCLUSIONS

The preliminary evidence of non-segmental differences within the gluteus minimus of swimmers (as opposed to non-swimmers) might implicate reduced-gravity environments in contributing to subsequent changes in deep stabiliser muscles. Such changes might predispose the athlete to a greater risk of lower limb injury during weight bearing activities.

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.

The effects of swimming training on bone tissue in adolescence

The aim was to analyze bone mineral content (BMC) and density (BMD) in regular swimming trained adolescents and the interaction that weigh-bearing sports may have on these values. Bone mass was evaluated by dual energy x-ray absorptiometry (DXA) and quantitative ultrasound (QUS) in 77 swimmers (34 females/43 males) and 52 normoactive controls (CG; 23 females/29 males) from 11 to 18 years. Swimmers who had performed or were performing other sports (OSP; 11 females/20 males) were compared with pure swimmers (PSW; 23 females/23 males). Both groups were compared with CG. Bone values were compared using analyses of covariance adjusting for height, calcium intake, subtotal lean (whole body lean minus head), and pubertal status. Male PSW showed lower BMD and BMC at several sites than male CG. However, for male OSP, only lumbar spine BMC was lower in OSP than male CG. Male PSW showed lower BMD and BMC when compared with male OSP. Female PSW showed higher arm BMD and lower leg BMC than female CG, while female OSP only presented lower leg BMC than female CG. Contrary to males, female-PSW presented higher BMD and BMC than female OSP. No differences in QUS values were found between swimmers and CG. To summarize, although more information is needed for females, it seems that for males, swimming is associated with lower BMC and BMD.

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.

Mechanical loading with or without weight-bearing activity: influence on bone strength index in elite female adolescent athletes engaged in water polo, gymnastics, and track-and-field

Bone health is considered not to benefit from water-based sports because of their weight-supported nature, but available evidence primarily relies on DXA technology. Our purpose was to investigate musculoskeletal health in the upper and lower body in well-trained adolescent female athletes using pQCT and compare these athletes with less-active, age- and sex-matched peers. Bone mineral content, volumetric cortical and trabecular BMD, total and cortical area, and bone strength index were assessed at the distal and proximal tibia and radius in four groups of adolescent females (mean age, 14.9 years) including water polo players (n = 30), gymnasts (n = 25), track-and-field athletes (n = 34), and nonactive controls (n = 28). Water polo players did not show any benefit in bone strength index or muscle size in the lower leg when compared with controls. In contrast, gymnasts showed 60.1 % and 53.4 % greater bone strength index at the distal and proximal tibia, respectively, than nonactive females (p < 0.05). Similarly, track-and-field athletes displayed 33.9 % and 14.7 % greater bone strength index at the distal and proximal tibia, respectively, compared with controls (p < 0.05). In the upper body, water polo players had 31.9 % greater bone strength index at the distal radius, but not the radial shaft, and 15.2 % larger forearm muscle cross-sectional area than controls (p < 0.05). The greatest musculoskeletal benefits in the upper body were found in gymnasts. In conclusion, despite training at an elite level, female water polo players did not show any benefits in musculoskeletal health in the lower leg and only limited benefits in the upper body when compared with nonactive girls.

The impact of different types of physical activity on total and regional bone mineral density in young Brazilian athletes

Bone turnover is affected by exercise throughout the lifespan, especially during childhood and adolescence. The objective of this study was to investigate the impact of different sports on total and regional bone mineral density in male Brazilian adolescent athletes. Forty-six adolescents aged 10-18 years participated in the study: 12 swimmers, 10 tennis players, 10 soccer players, and 14 sedentary individuals. The athletes had engaged in physical activities for more than 10 h per week in the previous 6 months. Bone mineral density of the lumbar spine (L1-L4), left proximal femur region, and whole body was evaluated by dual-energy X-ray absorptiometry. Results showed higher mean values in the proximal femur region of tennis and soccer players (1.02 ± 0.18; 0.96 ± 0.16, respectively) than swimmers and controls (0.91 ± 0.14 and 0.87 ± 0.06, respectively) (P < 0.05). In relation to the impact of sporting activities based on bone age determination, we observed significant differences in bone mineral density at all evaluated sites at the end of puberty (16-18 years) compared with 10-12 years, with increases of 78% in the lumbar spine, 47% in the proximal femur, and 38% in the whole body.

Bone cross-sectional geometry in male runners, gymnasts, swimmers and non-athletic controls: a hip-structural analysis study

Loading of the skeleton is important for the development of a functionally and mechanically appropriate bone structure, and can be achieved through impact exercise. Proximal femur cross-sectional geometry was assessed in the male athletes (n = 55) representing gymnastics, endurance running and swimming, and non-athletic controls (n = 22). Dual energy X-ray absorptiometry (iDXA, GE Healthcare, UK) measurements of the total body (for body composition) and the left proximal femur were obtained. Advanced hip structural analysis (AHA) was utilised to determine the areal bone mineral density (aBMD), hip axis length (HAL), cross-sectional area (CSA), cross-sectional moment of inertia (CSMI) and the femoral strength index (FSI). Gymnasts and runners had greater age, height and weight adjusted aBMD than in swimmers and controls (p < 0.05). Gymnasts and runners had greater resistance to axial loads (CSA) and the runners had increased resistance against bending forces (CSMI) compared to swimmers and controls (p < 0.01). Controls had a lower FSI compared to gymnasts and runners (1.4 vs. 1.8 and 2.1, respectively, p < 0.005). Lean mass correlated with aBMD, CSA and FSI (r = 0.365-0.457, p < 0.01), particularly in controls (r = 0.657-0.759, p < 0.005). Skeletal loading through the gymnastics and running appears to confer a superior bone geometrical advantage in the young adult men. The importance of lean body mass appears to be of particular significance for non-athletes. Further characterisation of the bone structural advantages associated with different sports would be of value to inform the strategies directed at maximising bone strength and thus, preventing fracture.

Swimming training increases the post-yield energy of bone in young male rats

The purpose of this study is to investigate the effects of non-weight-bearing exercise on growing bone. Male Wistar rats (7 week-old) were assigned to one baseline control group, one control group and two swimming training groups, which were trained with 2 and 4% body-weight mass added, respectively. After an 8-week training period, three groups showed significant development compared to the baseline control group. Among the three 15-week-old groups, swimming-trained rats were lower in body weight (BW), densitometry and size-related measurements. In femoral biomechanical testing, swimming training groups were significantly lower in yield moment and ultimate moment, which may be due to a significantly lower long bone cross-sectional moment of inertia. However, the two swimming groups were higher in post-yield energy absorption and displacement. Further, in estimated tissue-level biomaterial properties, no differences were shown in yield stress, strain or toughness among the three groups. Using BW as a covariate, results of ANCOVA showed no differences in size-related parameters among the three groups, and some parameters were even higher in the two swimming groups. Regarding Pearson's correlation, size-related parameters correlated well to BW and whole bone strength but not to tissue post-yield behaviors. In conclusion, when compared to age-matched control group, swimming rats showed lower bone strength and lower yield energy absolutely at the structural level, but similar yield stress and yield toughness at the tissue level. Moreover, swimming training benefited growing bone in post-yield behaviors. Further studies should investigate the parameters that contribute to this exercise-induced post-yield behavior.

Aquatic therapy: scientific foundations and clinical rehabilitation applications

The aquatic environment has broad rehabilitative potential, extending from the treatment of acute injuries through health maintenance in the face of chronic diseases, yet it remains an underused modality. There is an extensive research base supporting aquatic therapy, both within the basic science literature and clinical literature. This article describes the many physiologic changes that occur during immersion as applied to a range of common rehabilitative issues and problems. Because of its wide margin of therapeutic safety and clinical adaptability, aquatic therapy is a very useful tool in the rehabilitative toolbox. Through a better understanding of the applied physiology, the practitioner may structure appropriate therapeutic programs for a diverse patient population.

Cyclic loading comparison of Bio-SutureTak-#2 FiberWire and Bio Mini-Revo-#2 Hi-Fi suture anchor-sutures in cadaveric scapulae

This study compared tap-in Bio-SutureTak suture anchor-#2 FiberWire suture (Group 1) and screw-in Bio Mini-Revo suture anchor-#2 Hi-Fi suture (Group 2) fixation in the glenoid region of interest for Bankart repair, in addition to evaluation of isolated suture loop biomechanical properties under progressive incremental cyclic loads. With knowledge of glenoid apparent bone mineral density (BMD), implant preparation and fit characteristics, and following application of a light manual tensile load, the primary investigator scored each specimen for perceived within group biomechanical test performance using a 0-10 point modified visual analog scale. After scoring, 12 paired constructs were placed in a servo hydraulic device clamp, preloaded to 25 N, and cycled between 25 and 50 Hz with a 25 N load increase every 25 cycles. Group 2 withstood greater load (104.1 +/- 56 vs. 70 +/- 36.9 N, P = 0.04) and displaced more at failure (13 +/- 4.5 vs. 8.6 +/- 3.3 mm, P = 0.04). All Group 1 specimens failed prior to reaching 150 N, whereas 25% of Group 2 specimens (n = 3) failed at 200 N. All specimens failed by anchor pullout except for three Group 2 specimens that failed by eyelet breakage at 200 N. Isolated suture testing revealed that Group 1 sutures displaced less at each cyclic load (P = 0.028) and withstood greater failure loads (P = 0.028) than that of Group 2 sutures. Group 2 constructs displayed moderately strong relationships between perceived within group biomechanical test performance and ultimate load (r (2) = 0.55) and displacement at failure (r (2) = 0.67). Group 1 did not display significant relationships. Similar biomechanical performance between 50 and 125 N, greater load at failure, and superior biomechanical test prediction accuracy suggest that the screw-in type Bio Mini-Revo suture anchor-#2 Hi-Fi suture combination may be preferred for Bankart lesion repair in low apparent BMD glenoid processes. The #2 Hi-Fi suture, however, allowed significantly greater displacement than the #2 FiberWire suture at each progressive cyclic load interval.