Effect of long-term unilateral activity on bone mineral density of female junior tennis players

Impact loading exercise induced osteogenesis from childhood to early adulthood in tennis players aged 8-30 years

Osteogenesis with impact-loading exercise is often assessed by the extra bone growth induced in the loaded arm of tennis players. We used PRISMA to explore % bone mineral content (BMC) and area (BA) asymmetry in players 8-30 years according to weekly training hours, age, sex, maturity, and bone segment. Proper statistics for 70 groups were extracted by two reviewers from 18 eligible studies of low risk of bias (< 35, STROBE) and good quality (> 70%). The quality of the review was high (AMSTAR, 81%). Using "random effects" we tested moderation-specific meta-comparisons and meta-regressions. The loaded bones % hypertrophy was higher in BMC (19%) than BA (10%), and, with BMC and BA merged, in boys (17%) than girls (13%), in humerus (19%) than radius-ulna (14%), and in pubertal (19%) players. Weekly training hours were more important (43%) than sex (17%), puberty (14%) and bone (15%) in BMC, and puberty (48%) was more important than weekly training hours (19%), sex (12%), and radius-ulna (5%) in BA. The loaded bones % hypertrophy correlated with weekly training hours highly (> 0.60) in all maturity groups for BMC and BA, and moderately (0.41) in early adults for BA; it also correlated with age (≥ 0.60) in children and peripubertal players, but not (0.037) with starting age. Impact loading exercise favors mineralization twice than bone expansion, while puberty favors bone expansion about three times more than mineralization. The bone gains are higher for boys than girls, and for peripubertal than older players. The bone growth implications are discussed considering limitations and future research.

The path less traveled: Using structural equation modeling to investigate factors influencing bone functional morphology

OBJECTIVES

The relationship between an organism's mechanical environment and its bone strength has been long established by experimental research. Multiple intrinsic and extrinsic factors, including body mass, muscle strength, genetic background, and nutritional and/or hormonal status, are likely to influence bone deposition and resorption throughout the lifespan, complicating this relationship. Structural equation modeling (SEM) is uniquely positioned to parse this complex set of influences.

MATERIALS AND METHODS

Data from the Third National Health and Nutrition Examination Survey, including sex, total body mass, lean body mass, exercise frequency, peak body mass, and age, were analyzed using SEM to determine how they affect bone strength both individually and combined.

RESULTS

Body mass is typically the driver of cross-sectional area, but body mass and lean mass have similar effects on the polar moment of area (J). Peak body mass had a strong direct effect on J, despite decreasing strongly with increases in lean mass. Exercise also did not confer a large direct effect on cross-sectional area or J but did modify body mass and lean mass. In females, intentional weight loss was associated with decreased exercise levels.

DISCUSSION

SEM is a useful tool for parsing complex systems in bone functional morphology and has the potential to uncover causal links in the study of skeletal remodeling, including factors like weight loss or exercise that may have secondary effects.

Effects of the Type of Exercise Training on Bone Health Parameters in Adolescent Girls: A Systematic Review

Interventional studies offer strong evidence for exercise's osteogenic impact on bone particularly during growth. With rising osteoporosis rates in older women, enhancing bone strength early in life is crucial. Thus, investigating the osteogenic effects of different types of physical activities in young females is crucial. Despite varied findings, only two systematic reviews tried to explore this topic without examining how different types of exercise may affect bone health in adolescent girls. The first aim of this systematic review was to assess the impact of exercise training on bone health parameters in adolescent girls, and the second aim was to investigate whether the type of exercise training can modulate this effect. A systematic literature search was conducted using common electronic databases from inception - January 2023. Seven studies (355 participants) were eligible for inclusion in this systematic review. Two studies dealt with resistance training, 3 studies applied plyometric training, 1 study used team sports, and 1 study used dancing. Results indicate that plyometric training increases lumbar spine bone mass in adolescent girls. Well-designed randomized controlled trials with a proper training period (> 12 weeks) are needed to advocate a specific type of training which has the highest osteogenic effect.

Arthroscopic transosseous anchorless rotator cuff repair reduces bone defects related to peri-implant cyst formation: a comparison with conventional suture anchors using propensity score matching

BACKGROUND

The transosseous anchorless repair (ToR) technique was recently introduced to avoid suture anchor-related problems. While favorable outcomes of the ToR technique have been reported, no previous studies on peri-implant cyst formation with the ToR technique exist. Therefore, this study compared the clinical outcomes and prevalence of peri-implant cyst formation between the ToR technique and the conventional transosseous equivalent technique using suture anchors (SA).

METHODS

Cases with arthroscopic rotator cuff repair (ARCR) between 2016 and 2018 treated with the double-row suture bridge technique were retrospectively reviewed. Patients were divided into ToR and SA groups. To compare clinical outcomes, 19 ToR and 57 SA cases without intraoperative implant failure were selected using propensity score matching (PSM). While intraoperative implant failure rate was analyzed before PSM, retear rate, peri-implant cyst formation rate, and functional outcomes were compared after PSM.

RESULTS

The intraoperative implant failure rate (ToR, 8% vs. SA, 15.3%) and retear rate (ToR, 5.3% vs. SA, 19.3%) did not differ between the two groups (all P>0.05). However, peri-implant cysts were not observed in the ToR group, while they were observed in 16.7% of the SA group (P=0.008). Postoperative functional outcomes were not significantly different between the two groups (all P>0.05).

CONCLUSIONS

The ToR technique produced comparable clinical outcomes to conventional techniques. Considering the prospect of potential additional surgeries, the absence of peri-implant cyst formation might be an advantage of ToR. Furthermore, ToR might reduce the medical costs related to suture anchors and, thereby, could be a useful option for ARCR. Level of evidence: III.

Lower bone mineral density can be a risk for an enlarging bone marrow lesion: A longitudinal cohort study of Japanese women without radiographic knee osteoarthritis

OBJECTIVES

The aim is to elucidate the relationship between bone mineral density (BMD) at baseline and the change of bone marrow lesion (BML) during a 2-year follow-up (2YFU) period.

METHODS

Seventy-eight female participants (mean age: 54.9 ± 9.6 years) without radiographic knee osteoarthritis were eligible. Based on right-knee magnetic resonance imaging, maximum BML area (BMLa) was calculated by tracing the BML border. The change in BMLa was defined using the following formula: [2YFU] - [Baseline] = ΔBMLa. Positive ΔBMLa was defined as enlarged; negative ΔBMLa was defined as regressed. Dual-energy X-ray absorptiometry was performed to measure the BMD of distal radius. Young adult mean [YAM (%)] of the BMD was used for statistical analysis. Linear regression analysis was conducted with ΔBMLa as the dependent variable and YAM as the independent variable. Receiver operating characteristic curve and logistic regression analyses were conducted for YAM to predict the prevalence of BML enlargement or regression.

RESULTS

Twenty-six (33.3%) patients had enlarged BMLa, 12 (15.4%) participants showed regressing BMLa, and 40 (51.3%) patients remained stable. YAM was negatively associated with ΔBMLa (β: - 0.375, P = 0.046). The best predictor of BML enlargement risk was 85% (odds ratio: 8.383, P = 0.025).

CONCLUSIONS

Lower BMD could predict BML enlargement during a 2YFU period.

Asimetría entre los miembros superiores en jóvenes padelistas de competición

Existe escasa literatura sobre las asimetrías en el pádel, un deporte de naturaleza asimétrica. Para estudiar el desarrollo de asimetrías en este deporte se evaluó, con bioimpedancia, la masa magra de ambos miembros superiores de 96 jugadores de pádel jóvenes y de 76 esquiadores (grupo control) y se calculó el índice de simetría. Los jugadores de pádel tuvieron una asimetría entre ambos miembros superiores mayor que los esquiadores, cuando se consideró toda la muestra (7.2 ± 5 % vs. 1.4 ± 3.2 %; p < 0.001), en jugadores con un estado de madurez negativo (5,7 ± 3,2 % vs. 1,5 ± 3,8 %; p < 0,001) y en aquellos con un estado de madurez positivo (8,3 ± 5,8 % vs. 1,3 ± 2,4 %; p < 0,001). Este estudio revela que el pádel genera asimetrías de masa magra en los miembros superiores, incluso antes de la edad de crecimiento pico.

Sporting activity does not fully prevent bone demineralization at the impaired hip in athletes with amputation

There is lack of information about bone mineralization at the lumbar spine and bilateral hips of athletes with unilateral lower limb amputation. The present study assessed for the first time the areal bone mineral density at the lumbar spine and at the hip of the able and impaired leg by means of Dual-Energy X-Ray Absorptiometry using a large sample (N = 40) of male athletes. Results showed that bone demineralization in athletes with unilateral lower limb amputation is found at the impaired hip but not at the lumbar spine and may therefore be site-specific. The extent of hip demineralization was influenced by the level of amputation, with about 80% of athletes with above knee amputation and 10% of athletes with below knee amputation showing areal bone mineral density below the expected range for age. Nevertheless, a reduced percentage of fat mass and a lower fat-to-lean mass ratio in the residual impaired leg as well as a greater amount of weekly training was positively associated with bone mineralization at the impaired hip (partial correlation coefficients = 0.377–0.525, p = 0.040–0.003). Results showed that participation in adapted sport has a positive effect on bone health in athletes with unilateral lower limb amputation but is not sufficient to maintain adequate levels of bone mineralization at the impaired hip in athletes with above-knee amputation. Accordingly, physical conditioners should consider implementing sporting programs, according to the severity of the impairment, aimed at improving bone mineralization at the impaired hip and improve body composition in the residual impaired leg.

Tibial cortical and trabecular variables together can pinpoint the timing of impact loading relative to menarche in premenopausal females

OBJECTIVES

Though relationships between limb bone structure and mechanical loading have provided fantastic opportunities for understanding the lives of prehistoric adults, the lives of children remain poorly understood. Our aim was to determine whether or not adult tibial skeletal variables retain information about childhood/adolescent loading, through assessing relationships between cortical and trabecular bone variables and the timing of impact loading relative to menarche in premenopausal adult females.

METHODS

Peripheral quantitative computed tomography was used to quantify geometric and densitometric variables from the proximal tibial diaphysis (66% location) and distal epiphysis (4% location) among 81 nulliparous young adult female controls and athletes aged 19-33 years grouped according to intensity of impact loading both pre- and post-menarche: (1) Low:Low (Controls); (2) High:Low; (3) High:High; (4) Moderate:Moderate; (5) Low:Moderate. ANCOVA was used to compare properties among the groups adjusted for age, stature, and body mass.

RESULTS

Significant increases in diaphyseal total cross-sectional area and strength-strain index were documented among groups with any pre-menarcheal impact loading relative to groups with none, regardless of post-menarcheal loading history (p < .01). In contrast, significantly elevated distal trabecular volumetric bone mineral density was only documented among groups with recent post-menarcheal loading relative to groups with none, regardless of pre-menarcheal impact loading history (p < .01).

CONCLUSIONS

The consideration of diaphyseal cortical bone geometric and epiphyseal trabecular bone densitometric variables together within the tibia can identify variation in pre-menarcheal and post-menarcheal impact loading histories among premenopausal adult females.

Evaluation of the relationship between history of lower back pain and asymmetrical trunk range of motion

BACKGROUND

Low back pain (LBP) is a common complaint and preventive measures should be considered immediately. In addition, asymmetrical trunk motion, which occurs due to repetitive motion upon performing daily activities, may be one of the biomechanical factors to cause LBP.

OBJECTIVE

To investigate the characteristics of asymmetrical trunk motion in women with a history of LBP.

METHODS

Thirty-four women were dichotomously categorized into either the LBP or non-LBP group. Trunk active range of motion (RoM) upon sitting and standing were measured via a three-dimensional motion analysis system. Each RoM and rotation and side-flexion asymmetries were calculated and an unpaired t-tests were used to identify differences between each group.

RESULTS

Trunk rotation asymmetry upon sitting and standing position in LBP group was significantly greater than that in non-LBP group. Furthermore, trunk rotation angle upon sitting in LBP group was significantly larger than that in non-LBP group.

CONCLUSIONS

The limited RoM and asymmetry of trunk rotation may be due to imposed repetitive mechanical stress on habitual excessive motion, including most asymmetrical movements. Our findings indicated that a small trunk rotation angle and asymmetrical trunk rotation may be useful parameters to predict LBP onset or other musculoskeletal conditions of the trunk.

Biomechanical Evaluation on the Bilateral Asymmetry of Complete Humeral Diaphysis in Chinese Archaeological Populations

Diaphyseal cross-sectional geometry (CSG) is an effective indicator of humeral bilateral asymmetry. However, previous studies primarily focused on CSG properties from limited locations to represent the overall bilateral biomechanical performance of humeral diaphysis. In this study, the complete humeral diaphyses of 40 pairs of humeri from three Chinese archaeological populations were scanned using high-resolution micro-CT, and their biomechanical asymmetries were quantified by morphometric mapping. Patterns of humeral asymmetry were compared between sub-groups defined by sex and population, and the representativeness of torsional rigidity asymmetry at the 35% and 50% cross-sections (J35 and J50 asymmetry) was testified. Inter-group differences were observed on the mean morphometric maps, but were not statistically significant. Analogous distribution patterns of highly asymmetrical regions, which correspond to major muscle attachments, were observed across nearly all the sexes and populations. The diaphyseal regions with high variability of bilateral asymmetry tended to present a low asymmetrical level. The J35 and J50 asymmetry were related to the overall humeral asymmetry, but the correlation was moderate and they could not reflect localized asymmetrical features across the diaphysis. This study suggests that the overall asymmetry pattern of humeral diaphysis is more complicated than previously revealed by individual sections.

Examining developmental plasticity in the skeletal system through a sensitive developmental windows framework

Developmental plasticity facilitates energetically costly but potentially fitness-enhancing adjustments to phenotypic trajectories in response to environmental stressors, and thus may significantly impact patterns of growth, morbidity, and mortality over the life course. Ongoing research into epigenetics and developmental biology indicate that the timing of stress exposures is a key factor when assessing their impact on developmental processes. Specifically, stress experienced within sensitive developmental windows (SDWs), discrete developmental periods characterized by heightened energy requirements and rapid growth, may alter the pace and tempo of growth in ways that significantly influence phenotypic development over both the short and long term. In human skeletal biology, efforts to assess how developmental environments shape health outcomes over the life course could be enhanced by incorporating the SDW concept into existing methodological approaches. The goal of this article is to outline an interpretive framework for identifying and interpreting evidence of developmental stress in the skeletal system using the SDW concept. This framework provides guidance for the identification of elements most likely to capture evidence of stress most relevant to a study's core research questions, the interpretation of developmental stress exhibited by those elements, and the relationship of skeletal indicators of stress to the demographic patterning of morbidity and mortality. Use of the SDW concept in skeletal biology has the potential to enrich traditional approaches to addressing developmental origins of health and disease hypotheses, by targeting periods in which individuals are most susceptible to stress and thus most likely to exhibit plasticity in response.

Bone Microarchitecture and Strength Adaptation to Physical Activity: A Within-Subject Controlled HRpQCT Study

PURPOSE

Physical activity benefits bone mass and cortical bone size. The current study assessed the impact of chronic (≥10 yr) physical activity on trabecular microarchitectural properties and microfinite element analyses of estimated bone strength.

METHODS

Female collegiate-level tennis players (n = 15; age = 20.3 ± 0.9 yr) were used as a within-subject controlled model of chronic unilateral upper-extremity physical activity. Racquet-to-nonracquet arm differences at the distal radius and radial diaphysis were assessed using high-resolution peripheral quantitative computed tomography. The distal tibia and the tibial diaphysis in both legs were also assessed, and cross-country runners (n = 15; age = 20.8 ± 1.2 yr) included as controls.

RESULTS

The distal radius of the racquet arm had 11.8% (95% confidence interval [CI] = 7.9% to 15.7%) greater trabecular bone volume/tissue volume, with trabeculae that were greater in number, thickness, connectivity, and proximity to each other than that in the nonracquet arm (all P < 0.01). Combined with enhanced cortical bone properties, the microarchitectural advantages at the distal radius contributed a 18.7% (95% CI = 13.0% to 24.4%) racquet-to-nonracquet arm difference in predicted load before failure. At the radial diaphysis, predicted load to failure was 9.6% (95% CI = 6.7% to 12.6%) greater in the racquet versus nonracquet arm. There were fewer and smaller side-to-side differences at the distal tibia; however, the tibial diaphysis in the leg opposite the racquet arm was larger with a thicker cortex and had 4.4% (95% CI = 1.7% to 7.1%) greater strength than the contralateral leg.

CONCLUSION

Chronically elevated physical activity enhances trabecular microarchitecture and microfinite element estimated strength, furthering observations from short-term longitudinal studies. The data also demonstrate that tennis players exhibit crossed symmetry wherein the leg opposite the racquet arm possesses enhanced tibial properties compared with in the contralateral leg.

Whole-body morphological asymmetries in high-level female tennis players: A cross‑sectional study

This cross-sectional study aimed to examine the degree of whole-body morphological asymmetries in female tennis players. Data were collected in 19 high-level female tennis players (21.3 ± 3.4 years). Based on anthropometric measurements (upper arm, lower arm, wrist, upper leg and lower leg circumferences as well as elbow and knee widths) and dual x-ray absorptiometry research scans (bone mineral density (BMD), bone mineral content (BMC), lean mass (LM), fat mass (FM) as well as humerus, radio-ulnar, femur and tibia bone lengths), within-subject morphological asymmetries for both upper (dominant vs. non-dominant) and lower (contralateral vs. ipsilateral) extremities were examined. Upper arm (p = 0.015), lower arm (p < 0.001) and wrist circumferences (p < 0.001), elbow width (p = 0.049), BMD (p < 0.001), BMC (p < 0.001), LM (p = 0.001), humerus (p = 0.003) and radio-ulnar bone length (p < 0.001) were all greater in the dominant upper extremity. BMC (p < 0.001) and LM (p < 0.001) were greater in the contralateral lower extremity, whereas FM (p = 0.028) was greater in the ipsilateral lower extremity. This is the first study to report significant side-to-side differences in both upper and lower extremities in high-level female tennis players.

The Genetic Architecture of High Bone Mass

The phenotypic trait of high bone mass (HBM) is an excellent example of the nexus between common and rare disease genetics. HBM may arise from carriage of many 'high bone mineral density [BMD]'-associated alleles, and certainly the genetic architecture of individuals with HBM is enriched with high BMD variants identified through genome-wide association studies of BMD. HBM may also arise as a monogenic skeletal disorder, due to abnormalities in bone formation, bone resorption, and/or bone turnover. Individuals with monogenic disorders of HBM usually, though not invariably, have other skeletal abnormalities (such as mandible enlargement) and thus are best regarded as having a skeletal dysplasia rather than just isolated high BMD. A binary etiological division of HBM into polygenic vs. monogenic, however, would be excessively simplistic: the phenotype of individuals carrying rare variants of large effect can still be modified by their common variant polygenic background, and by the environment. HBM disorders-whether predominantly polygenic or monogenic in origin-are not only interesting clinically and genetically: they provide insights into bone processes that can be exploited therapeutically, with benefits both for individuals with these rare bone disorders and importantly for the many people affected by the commonest bone disease worldwide-i.e., osteoporosis. In this review we detail the genetic architecture of HBM; we provide a conceptual framework for considering HBM in the clinical context; and we discuss monogenic and polygenic causes of HBM with particular emphasis on anabolic causes of HBM.

Are entheseal changes and cross-sectional properties associated with the shape of the upper limb?

OBJECTIVES

Reconstruction of the activity of past human populations can be carried out using various skeletal markers; however, the relationship between these methods is not fully understood. Therefore, the main aim of this article is to analyze the relationship between entheseal changes, cross-sectional properties, and variability in the shape of the upper limb.

MATERIALS AND METHODS

The analyzed material consisted of CT images of 71 right scapulae, humeri, and ulnae belonging to the same individuals from a mediaeval population located in Poland. For each series of bones for the same individual, skeletal markers such as: cross-sectional properties, entheses and shape variation were assessed. Next, correlations between these three skeletal indicators were calculated.

RESULTS

In general, the models showed that only sex influences entheses. Multivariate regression revealed significant correlation only between ulnar auricular surface shape and two types of mean score for entheses.

DISCUSSION

The findings are inconsistent and stand in contradiction to other research; therefore, we suggest that an assessment of individual activity should be carried out, using as many post-cranial elements as possible and a variety of methods. This approach will ensure more accurate reconstruction of the activity levels and patterns of archeological groups.

Bone asymmetries in the limbs of children tennis players: testing the combined effects of age, sex, training time, and maturity status

This study estimated upper and lower limb bone mineral content (BMC) and bone area (BA) in 48 children tennis players (24 boys, 24 girls) aged 7-13 years. The sample comprised four age groups (8.2 ± 0.44, 9.5 ± 0.13, 10.5 ± 0.33, 12.2 ± 0.58). BMC and BA were measured via DXA, and sexual maturity by the Tanner scale, then used as a binary: prepubertal vs peripubertal. Total training time (TTT) included all playing years. Arms were asymmetric and legs symmetric. Boys were more asymmetric than girls in BMC (18% vs 13%) and BA (11% vs 8%). Pre-pubertal children were less asymmetric than peri-pubertal in BMC (14% vs 18%) and in BA (9.4% vs 10%). Bone growth changed with age and TTT markedly better in the dominant arm. The linear combination of TTT, sex, and maturity binary extracted 59% of BMC asymmetry and only 21% of BA asymmetry. For both bone parameters the sex effect was significant only for the pre-pubertal children. Training time constitutes the best predictor of bone asymmetry compared to age, sex, and maturity; when adequate, playing arm bone hypertrophy may be detectable at the age of 7-8 years. These results have health and performance implications.

Karate Training Improves Skeletal Status Assessed by Quantitative Ultrasound in Girls and Premenopausal Women

PURPOSE

The aim of the study was to assess the influence of regular karate training on the skeletal status evaluated by quantitative ultrasound (QUS) in females.

METHODS

A group of 132 karate training girls and women at mean age 19.57 (standard deviation [SD] 7.64) yr (range 7.3-45.3 yr) and 322 age-, sex- and body size-matched controls were enrolled into the study. Mean training duration in the karate group was 7.52 (SD 5.05) yr and mean training frequency was 2.97 (SD 1.21) per wk. The QUS measurements were performed at hand proximal phalanges, using a DBM Sonic 1200 (IGEA, Carpi, Italy) sonographic device, which measures amplitude-dependent speed of sound (Ad-SoS [m/s]).

RESULTS

The results of Ad-SoS obtained in karatekas were generally higher than in controls with significant difference for prepubertal girls (1966.2 [SD 46.2] vs 1942.7 [SD 38.4]; p < 0.05) and for adult women (2124.4 [SD 48.0] vs 2105.3 [SD 54.0]; p < 0.05).

CONCLUSIONS

Regular karate training is a factor that is positively associated with results of the QUS measurements at hand phalanges in exercising females and its impact is most strongly pronounced in prepuberty and adulthood.

Contribution of High School Sport Participation to Young Adult Bone Strength

INTRODUCTION

Nearly 8 million American adolescents participate in sports. Participation declines in young adulthood.

PURPOSE

This study assessed longitudinal effects of high school sport participation and muscle power on young adult bone strength.

METHODS

Two hundred twenty-eight young adults from the Iowa Bone Development Study completed an interscholastic sport participation questionnaire. Current physical activity (PA) behaviors were assessed via questionnaire. Dual x-ray absorptiometry assessed hip areal bone mineral density and was used with hip structure analysis to estimate femoral neck section modulus and hip cross-sectional area. Peripheral quantitative computed tomography provided strength-strain index and bone strength index at 38% and 4% midshaft tibial sites, respectively. Vertical jump estimated muscle power at 17 yr. Sex-specific multiple linear regression predicted young adult bone outcomes based on sport participation groups. Mediation analysis analyzed the effects of muscle power on relationships between sport participation and bone strength.

RESULTS

At follow-up, males participating in any interscholastic sport had greater bone strength than males who did not participate in sport. The explained variability in bone outcomes was 2% to 16%. Females who participated in sports requiring muscle power had greater bone strength than females who did not participate in sports or females who participated in nonpower sports (explained variability was 4%-10%). Muscle power mediated 24.7% to 41% of the effect of sport participation on bone outcomes in males and 19.4% to 30% in females.

CONCLUSIONS

Former male interscholastic sport participants and female interscholastic power sport participants have stronger bones than peers even when adjusting for current PA. Muscle power did not fully explain differences in all bone outcomes, suggesting that sport participation has additional bone health benefits.

Adaptation of the proximal humerus to physical activity: A within-subject controlled study in baseball players

The proximal humerus is a common, yet understudied site for osteoporotic fracture. The current study explored the impact of prolonged physical activity on proximal humerus bone health by comparing bone properties between the throwing and nonthrowing arms within professional baseball players. The proximal humerus in throwing arms had 28.1% (95% CI, 17.8 to 38.3%) greater bone mass compared to nonthrowing arms, as assessed using dual-energy x-ray absorptiometry. At the level of the surgical neck, computed tomography revealed 12.0% (95% CI, 8.2 to 15.8%) greater total cross-sectional area and 31.0% (95% CI, 17.8 to 44.2%) greater cortical thickness within throwing arms, which contributed to 56.8% (95% CI, 44.9 to 68.8%) greater polar moment of inertia (i.e., estimated ability to resist torsional forces) compared to nonthrowing arms. Within the humeral head and greater tubercle regions, throwing arms had 3.1% (95% CI, 1.1 to 5.1%) more trabecular bone, as assessed using high-resolution magnetic resonance imaging. Three-dimensional mapping of voxel- and vertex-wise differences between arms using statistical parametric mapping techniques revealed throwing arms had adaptation within much of the proximal diaphysis, especially the posterolateral cortex. The pattern of proximal diaphysis adaptation approximated the pattern of strain energy distribution within the proximal humerus during a fastball pitch derived from a musculoskeletal and finite element model in a representative player. These data demonstrate the adaptive ability of the proximal humerus to physical activity-related mechanical loads. It remains to be established how they translate to exercise prescription to improve bone health within the proximal humerus; however, they provide unique insight into the relationship between prolonged loading and skeletal adaptation at a clinically relevant osteoporotic site.

Maternal investment, maturational rate of the offspring and mechanical competence of the adult female skeleton

LAY SUMMARY

Girls with a slower life history trajectory build a larger body with larger and mechanically stronger bones. Thus, variation in the emergence of slower versus faster life history trajectories during development can have consequences for bone mechanical competence, and hence fracture risk in adulthood.

BACKGROUND AND OBJECTIVES

Variation in life history trajectory, specifically relative investment in growth versus reproduction, has been associated with chronic disease risk among women, but whether this scenario extends to skeletal health and fracture risk is unknown. This study investigates the association of life history traits (proxies for maternal investment and maturational rate) with female bone outcomes in adulthood.

METHODOLOGY

Body size variables, regional muscle and fat areas, and cross-sectional bone size and strength outcomes were obtained from 107 pre-menopausal women encompassing a wide range of physical activity levels. Developmental parameters (birth weight, age at menarche) were obtained from questionnaires.

RESULTS

High birth weight was significantly associated with a proportionately larger body and larger, mechanically stronger bones, independently of physical activity level. It was also positively but non-significantly associated with age at menarche. Later menarche was significantly associated with larger and mechanically stronger bones and substantially less absolute and relative regional subcutaneous fat. Age at menarche exhibited stronger relationships with adult adiposity than did physical activity.

CONCLUSIONS AND IMPLICATIONS

Both larger birth weight and later menarche contribute to a slower life history trajectory, which is associated with greater body size, leanness and bone mechanical competence in early adulthood. In contrast, earlier sexual maturity prioritized energy allocation in adiposity over body size and skeletal strength. Thus, the level of maternal investment and the woman's own life history trajectory shape investment in skeletal properties, with implications for fracture risk later in life.

Exercise Early and Often: Effects of Physical Activity and Exercise on Women's Bone Health

In 2011 over 1.7 million people were hospitalized because of a fragility fracture, and direct costs associated with osteoporosis treatment exceeded 70 billion dollars in the United States. Failure to reach and maintain optimal peak bone mass during adulthood is a critical factor in determining fragility fracture risk later in life. Physical activity is a widely accessible, low cost, and highly modifiable contributor to bone health. Exercise is especially effective during adolescence, a time period when nearly 50% of peak adult bone mass is gained. Here, we review the evidence linking exercise and physical activity to bone health in women. Bone structure and quality will be discussed, especially in the context of clinical diagnosis of osteoporosis. We review the mechanisms governing bone metabolism in the context of physical activity and exercise. Questions such as, when during life is exercise most effective, and what specific types of exercises improve bone health, are addressed. Finally, we discuss some emerging areas of research on this topic, and summarize areas of need and opportunity.

Exercise for Bone in Childhood-Hitting the Sweet Spot

PURPOSE

The goal of the current work is to challenge the enduring notion that prepuberty is the optimum timing for maximum bone response to exercise in childhood and to present the evidence that early puberty is a more potently receptive period.

METHOD

The relevant literature is reviewed and the causes of the misconception are addressed in detail.

RESULTS

Contrary to prevailing opinion, ample evidence exists to suggest that the peripubertal years represent the developmental period during which bone is likely to respond most robustly to exercise intervention.

CONCLUSION

Public health initiatives that target bone-specific exercise interventions during the pubertal years are likely to be the most effective strategy to harness the increased receptiveness of the growing skeleton to mechanical loading.

Physical and Physiological Demands of Recreational Team Handball for Adult Untrained Men

Lack of motivation to exercise was reported as a major cause of sedentary behavior in adulthood. This descriptive study examines the acute physical and physiological demands of recreational team handball and evaluates whether it could be suggested as an exercise mode for fitness and health enhancement in 33-55-year-old untrained men. Time-motion, heart rate (HR), and blood lactate analyses were obtained from 4 recreational matches. Mean distance covered during the 60 min matches was 6012 ± 428 m. The players changed match activity 386 ± 70 times, of which high-intensity runs and unorthodox movements amounted to 59 ± 18 and 26 ± 26 per match, respectively. The most frequent highly demanding playing actions were jumps and throws. Match average and peak HR were 82 ± 6% and 93 ± 5%  HRmax, respectively. Players exercised at intensities between 81 and 90%  HRmax for 47% (28 ± 14 min) and >90%  HRmax for 24% (14 ± 15 min) of total match time. Match average and peak blood lactate values were 3.6 ± 1.3 and 4.2 ± 1.2 mM, respectively. Recreational team handball is an intermittent high-intensity exercise mode with physical and physiological demands in the range of those found to have a positive effect on aerobic, anaerobic, and musculoskeletal fitness in adult individuals. Training studies considering recreational team handball as a health enhancing intervention are warranted.

The Effects of Hormonal Therapy and Exercise on Bone Turnover in Postmenopausal Women: A Randomised Double-Blind Pilot Study

INTRODUCTION

Hormone replacement therapy (HRT) and walking were investigated independently and in combination, to determine which treatment provided most effect on bone turnover in postmenopausal women.

METHODS

Using a randomised double-blind pilot study, 10 subjects received HRT (transdermal estradiol, 50 μg/day and oral MPA 5 mg/day) and 12 received placebo for 20 weeks. Following a baseline period of treatment, both groups undertook a graduated walking regimen, which increased in intensity, duration and frequency parameters from weeks 8-20. Measurements of aerobic capacity, female sex hormones, bone formation markers [osteocalcin (OC) and bone alkaline phosphatase (BAP)] and bone resorption markers [deoxypyridinoline (DPD) and pyridinoline (PYR)] were measured at baseline (T1), week 8 (T2) and week 20 (T3).

RESULTS

Age, time of postmenopause, weight or body mass index were no different between each groups. The HRT group had significantly higher estradiol levels compared with the placebo group at T2 and T3. FSH and LH levels were significantly reduced following HRT. DPD and PYR were significantly reduced from baseline levels at T2 and T3 with HRT. No significant changes occurred in OC or BAP levels with either HRT or walking. Walking did not change bone turnover markers in either the HRT or placebo group.

CONCLUSION

HRT reduces bone resorption, however, walking alone at the intensity and duration prescribed, or the combination of HRT and walking, provided no additional benefit after menopause. Therefore, HRT, but not walking is an effective treatment in reducing bone turnover in postmenopause women.

In Vivo Hip Morphology and Kinematics in Elite Baseball Pitchers

PURPOSE

To compare passive and real-time active hip range of motion (ROM) in asymptomatic collegiate pitchers, to investigate whether differences in hip morphology and ROM exist between lead and trail hips, and to relate active hip ROM during the pitch to hip morphology and femoroacetabular impingement.

METHODS

Eleven collegiate baseball pitchers participated in kinematic testing that involved throwing 4 fastball pitches while wearing a full-body inertial-based motion-capture system. Passive flexion and rotation of each hip were measured using a goniometer. Nine pitchers also underwent a computed tomography (CT) pelvic scan, from which subject-specific computer models for each hip were created. Morphologic measurements were calculated from the models, and the models were tested for impingement during simulated pitching.

RESULTS

Hip flexion was the only passive ROM measurement showing a significant difference between the lead and trail hips (mean difference [MD], 4°; P = .027). During the pitching motion, within-individual differences were discovered between the lead and trail hips for flexion (MD, 34°; P < .0001), extension (MD, 26°; P < .0001), abduction (MD, 8°; P = .026), adduction (MD, 6°; P = .008), external rotation (MD, 20°; P = .001), and total arc of rotation (MD, 13°; P = .001). There were no significant differences in morphologic measures between the lead and trail hips. Dynamic CT modeling did not lead to bony impingement in any subject.

CONCLUSIONS

Asymptomatic collegiate pitchers approach their extremes of passive hip rotation when executing a fastball pitch. No differences were found in passive hip ROM or morphology other than a small difference in passive hip flexion. Dynamic CT modeling did not show femoroacetabular impingement during the pitching motion.

CLINICAL RELEVANCE

Hip dysmorphology or poor pitching mechanics may lead to a high risk of bony impingement because pitchers have little reserve hip motion during the fastball pitch.

Mechanical and metabolic interactions in cortical bone development

OBJECTIVES

Anthropological studies of cortical bone often aim to reconstruct either habitual activities or health of past populations. During development, mechanical loading and metabolism simultaneously shape cortical bone structure; yet, few studies have investigated how these factors interact. Understanding their relative morphological effects is essential for assessing human behavior from skeletal samples, as previous studies have suggested that interaction effects may influence the interpretation from cortical structure of physical activity or metabolic status.

MATERIAL AND METHODS

This study assesses cross-sectional geometric and histomorphometric features in bones under different loading regimes (femur, humerus, rib) and compares these properties among individuals under different degrees of metabolic stress. The study sample consists of immature humans from a late medieval Lithuanian cemetery (Alytus, 14th-18th centuries AD). Analyses are based on the hypothesis that metabolic bone loss is distributed within the skeleton in a way that optimizes mechanical competency.

RESULTS

Results suggest mechanical compensation for metabolic bone loss in the cross-sectional properties of all three bones (especially ribs), suggesting a mechanism for conserving adequate bone strength for different loads across the skeleton. Microscopic bone loss is restricted to stronger bones under high loads, which may mitigate fracture risk in areas of the skeleton that are more resistive to loading, although alternative explanations are examined.

DISCUSSION

Distributions of metabolic bone loss and subsequent structural adjustments appear to preserve strength. Nevertheless, both mechanics and metabolism have a detectable influence on morphology, and potential implications for behavioral interpretations in bioculturally stressed samples due to this interaction are explored. Am J Phys Anthropol 160:317-333, 2016. © 2016 Wiley Periodicals, Inc.

Does Exercise Influence Pediatric Bone? A Systematic Review

BACKGROUND

Periods of growth are thought to be the best time to increase bone mineral content, bone area, and areal bone mineral density (aBMD) through increased loading owing to high rates of bone modeling and remodeling. However, questions remain regarding whether a benefit of exercise is seen at all bone sites, is dependent on pubertal status or sex of the child, or whether other factors such as diet modify the response to exercise.

QUESTIONS/PURPOSES

We asked: (1) Does bone-loading exercise in childhood consistently increase bone mineral content, bone area, or aBMD? (2) Do effects of exercise differ depending on pubertal status or sex? (3) Does calcium intake modify the bone response to exercise?

METHODS

A literature search identified 22 unique trials for inclusion in this meta-analysis of the effect of exercise on bone changes by bone site, pubertal status, and sex. Sample sizes ranged from 16 to 410 subjects 3 to 18 years old with length of intervention ranging from 3 to 36 months. Fifteen of 22 trials were randomized (child randomized in nine, classroom/school randomized in six) and seven were observational trials. Ten trials were Level 2 and 11 were Level 3 based on the Oxford Centre for Evidence-Based Medicine criteria. Random effects models tested the difference (intervention mean effect-control mean effect) in percent change in bone mineral content, bone area, and aBMD. Meta-regression was used to identify sources of heterogeneity and funnel plots were used to assess publication bias.

RESULTS

Children assigned to exercise had greater mean percent changes in bone mineral content and aBMD than children assigned to the control groups. Mean differences (95% CI) in bone mineral content percent change between intervention and control groups at total body (0.8; 95% CI, 0.3-1.3; p = 0.003), femoral neck (1.5; 95% CI, 0.5-2.5; p = 0.003), and spine (1.7; 95% CI, 0.4-3.1; p = 0.01) were significant with no differences in bone area (all p > 0.05). There were greater percent changes in aBMD in intervention than control groups at the femoral neck (0.6; 95% CI, 0.2-1.1; p = 0.006) and spine (1.2; 95% CI, 0.6-1.8; p < 0.001). Benefit of exercise was limited to children who were prepubertal (bone mineral content: total body [0.9; 95% CI, 0.2-1.7; p = 0.01], femoral neck [1.8; 95% CI, 0.0-3.5; p = 0.047], spine [3.7; 95% CI, 0.8-6.6; p = 0.01], and aBMD: femoral neck [0.6; 95% CI, -0.1-1.2; p = 0.07], spine [1.5; 95% CI, 0.7-2.3; p < 0.001]), with no differences among children who were pubertal (all p > 0.05). Changes in aBMD did not differ by sex (all p > 0.05), although the number of studies providing male-specific results was small (six of 22 eligible studies included boys). There was significant heterogeneity in bone mineral content and bone area for which a source could not be identified. Heterogeneity in spine aBMD was reduced by including calcium intake and intervention length as covariates. Three trials designed to determine whether calcium intake modified the bone response to exercise all reported a greater effect of exercise on leg bone mineral content in children randomized to receive supplemental calcium than those receiving placebo.

CONCLUSIONS

Exercise interventions during childhood led to 0.6% to 1.7% greater annual increase in bone accrual, with effects predominantly among children who were prepubertal. If this effect were to persist into adulthood, it would have substantial implications for osteoporosis prevention. It is important to identify sources of heterogeneity among studies to determine factors that might influence the bone response to increased exercise during growth.

LEVEL OF EVIDENCE

Level II, therapeutic study.

Geometric morphometrics: does the appearance of the septal aperture depend on the shape of ulnar processes?

Many theories have been suggested to explain the etiology of septal apertures (SA) of the humerus. The influence of genes, the size of ulnar processes, joint laxity, and bone robusticity, have been discussed; however, the problem has not yet been solved. The main aim of this study was to examine the influence of ulnar and humeri shape on septal aperture formation, using geometric morphometric analyses. Skeletal material from an early-mediaeval cemetery located in Western Poland was used. The material comprised two groups: (1) ulnae and humeri with septal apertures, (2) ulnae and humeri without septal apertures. From a CT image, three-dimensional reconstructions were obtained for all bones. Then, 25 landmarks were distributed on each proximal end of the ulnae and 30 landmarks on the distal ends of the humeri. Shape differences between ulnae in joints with and without SA were significant for the left and right sides of the body. The shapes of the left and right distal ends of humeri with SA differed significantly from those without SA. Similar results were obtained for the right side of the body. Ulnae from joints with SA were characterized by a more pronounced olecranon process, a smaller articulated coronoid process and a more tightly curved trochlear notch than ulnae from joints without SA. Humeri with SA included wider and deeper olecranon fossae and smaller and less curved articular surfaces. These results partly coincide with the results of other research indicating the influence of olecranon processes on lamina perforation.

Assessing the Awareness and Behaviors of U.S. High School Nurses With Respect to the Female Athlete Triad

Female high school athletes are an at-risk population for the Female Athlete Triad—a syndrome including low energy availability (with or without disordered eating), menstrual dysfunction, and low bone mineral density. School nurses can play an important role in reducing the health burden of this syndrome, by educating coaches and athletes, and by referring symptomatic student-athletes to appropriate community resources for evaluation and treatment. This study assessed knowledge, attitudes, communication, and referral behaviors of U.S. high school nurses about the Female Athlete Triad. Participants were a random sample of 370 U.S. high school nurses. The results indicated that only 19% of the nurses were able to identify the three components of the Triad and only 25% reported that they work proactively with coaches to help prevent health issues among their female athletes. Over 95% expressed interest in learning more about the Triad. Implications for educational program design are discussed.

Skeletal effects of bariatric surgery: examining bone loss, potential mechanisms and clinical relevance

Bariatric surgery is the most effective therapeutic approach to morbid obesity, resulting in substantial weight loss and improved cardiometabolic profiles; however, a growing body of evidence suggests that bariatric procedures increase both skeletal fragility and the risk of related future fracture secondary to excessive bone loss. Prospective evidence shows that areal bone mineral density (BMD) assessed by dual energy X-ray absorptiometry (DXA) declines by as much as 14% in the proximal femoral regions, including the femoral neck and total hip, 12 months postoperatively. Lumbar spine areal BMD outcomes show greater 12-month postoperative variability across surgical procedures (-8 to +6%) and contrast with no change in volumetric BMD outcomes measured by quantitative computed tomography. Diminished mechanical loading, micronutrient deficiency and malabsorption, along with neurohormonal alterations, offer plausible underlying mechanisms to explain these observed post-bariatric bone changes, but most remain largely unsubstantiated in this population. Importantly, DXA-based skeletal imaging may have limited utility in accurately detecting bone change in people undergoing bariatric surgery; partly because excessive tissue overlying bone increases the variability of areal BMD outcomes. Moreover, a paucity of fracture and osteoporosis incidence data raises questions about whether marked post-bariatric surgery bone loss is clinically relevant or a functional adaptation to skeletal unloading. Future studies that use technology which is able to accurately capture the site-specific volumetric BMD and bone architectural changes that underpin bone strength in people undergoing bariatric surgery, that consider mechanical load, and that better quantify long-term fracture and osteoporosis incidence are necessary to understand the actual skeletal effects of bariatric surgery.

Divergence in male and female manipulative behaviors with the intensification of metallurgy in Central Europe

Humeral morphology has been shown to reflect, in part, habitual manipulative behaviors in humans. Among Central European agricultural populations, long-term social change, increasing task specialization, and technological innovation all had the potential to impact patterns of habitual activity and upper limb asymmetry. However, systematic temporal change in the skeletal morphology of agricultural populations in this region has not been well-characterized. This study investigates diachronic patterns in humeral biomechanical properties and lengths among 174 adult Central European agriculturalists through the first ∼ 5400 years of farming in the region. Greater asymmetry in biomechanical properties was expected to accompany the introduction of metallurgy, particularly in males, while upper limb loading patterns were expected to be more similar between the Bronze and Iron Ages. Results revealed a divergence in the lateralization of upper limb biomechanical properties by sex between the Early/Middle Neolithic and Early/Middle Bronze Age. Neolithic females had significantly more variable properties than males in both humeri, while Bronze Age female properties became homogeneous and very symmetrical relative to the right-biased lateralization of contemporaneous males. The Bronze Age to Iron Age transition was associated with morphological change among females, with a significant increase in right-biased asymmetry and a concomitant reduction in sexual dimorphism. Relative to biomechanical properties, humeral length variation and asymmetry were low though some significant sexual dimorphism and temporal change was found. It was among females that the lateralization of humeral biomechanical properties, and variation within them, changed most profoundly through time. This suggests that the introduction of the ard and plow, metallurgical innovation, task specialization, and socioeconomic change through ∼ 5400 years of agriculture impacted upper limb loading in Central European women to a greater extent than men.

An in-school exercise intervention to enhance bone and reduce fat in girls: the CAPO Kids trial

The CAPO Kids trial was a 9-mo, controlled, school-based intervention to examine the effects of a novel, brief, high intensity exercise regime on indices of musculoskeletal and metabolic health in pre- and early-pubertal girls.

METHODS

A total of 151 pre- and early-pubertal girls (10.6±0.6years), recruited from two different schools consented to participate; 76 in the exercise group (EX) and 75 in the control group (CON). EX performed 10min bouts of thrice-weekly jumping plus capoeira (a Brazilian sport that combines martial art with dance), along with usual physical education (PE) activities. CON continued usual PE alone. Maturity, weight, height, waist circumference, resting heart rate and blood pressure, maximal vertical jump, and aerobic capacity were determined using standard clinical and field measures. Calcaneal broadband ultrasound attenuation (BUA) and stiffness index (SI) were determined from quantitative ultrasonometry. A subsample of children also underwent DXA and pQCT measures. Prior physical activity participation and daily calcium consumption were determined from validated instruments.

RESULTS

EX girls improved BUA more than CON (+4.5% vs. +1.4%, p=0.019). Resting heart rate (-7.2% vs. -1.8%, p<0.01), maximal vertical jump (+13.4% vs. -1.2%, p<0.001), estimated maximal oxygen consumption (+10.6% vs. +1.0%, p<0.001), and waist circumference (+2.7% vs. +5.6%, p<0.001) also improved more for EX than CON.

CONCLUSION

Ten minutes of high intensity exercise (capoeira and jumping) three times a week in the primary school setting enhances musculoskeletal and metabolic outcomes in pre- and early-pubertal girls without disrupting the academic schedule. The programme, amenable to broad-scale school implementation, would confer meaningful public health benefits.

Rowing performance, body composition, and bone mineral density outcomes in college-level rowers after a season of concurrent training

PURPOSE

To assess changes in body composition, lumbar-spine bone mineral density (BMD), and rowing performance in college-level rowers over a competition season.

METHODS

Eleven Division I college rowers (mean ± SD 21.4 ± 3.7 y) completed 6 testing sessions throughout the course of their competition season. Testing included measurements of fat mass, bone-free lean mass (BFLM), body fat (%BF), lumbar-spine BMD, and 2000-m time-trial performance. After preseason testing, rowers participated in a periodized training program, with the addition of resistance training to the traditional aerobic-training program.

RESULTS

Significant (P < .05) improvements in %BF, total mass, and BFLM were observed at midseason and postseason compared with preseason. Neither lumbar-spine BMD nor BMC significantly changed over the competitive season (P > .05). Finally, rowing performance (as measured by 2000-m time and average watts achieved) significantly improved at midseason and postseason compared with preseason.

CONCLUSION

Our results highlight the efficacy of a seasonal concurrent training program serving to improve body composition and rowing performance, as measured by 2000-m times and average watts, among college-level rowers. Our findings offer practical applications for coaches and athletes looking to design a concurrent strength and aerobic training program to improve rowing performance across a season.

Load-induced changes in bone stiffness and cancellous and cortical bone mass following tibial compression diminish with age in female mice

The vertebrate skeleton is an adaptive structure that responds to mechanical stimuli by increasing bone mass under increased mechanical loads. Although experimental animal models have shown the anabolic cortical bone response to applied load decreases with age, no consensus exists regarding whether this adaptive mechanism is affected by age in cancellous bone, the tissue most impacted by age-related bone loss. We used an established murine in vivo tibial loading model to characterize the load-induced cancellous, cortical and whole-bone responses to mechanical stimuli in growing and mature female mice at 6, 10 and 16 weeks of age. The effects of applied load on tibial morphology and stiffness were determined using microcomputed tomography and in vivo bone strains measured at the medial tibial midshaft during applied loading. At all ages, 2 weeks of applied load produced larger midshaft cortical cross-sectional properties (+13-72%) and greater cancellous bone volume (+21-107%) and thicker trabeculae (+31-68%) in the proximal metaphyses of the loaded tibiae. The relative anabolic response decreased from 6 to 16 weeks of age in both the cancellous and cortical envelopes. Load-induced tibial stresses decreased more in 6-week-old mice following loading, which corresponded to increased in vivo tibial stiffness. Stiffness in the loaded tibiae of 16-week-old mice decreased despite moderately increased cortical cross-sectional geometry, suggesting load-induced changes in bone material properties. This study shows that the cancellous and cortical anabolic responses to mechanical stimuli decline with age into adulthood and that cortical cross-sectional geometry alone does not necessarily predict whole-bone functional stiffness.

Young male soccer players exhibit additional bone mineral acquisition during the peripubertal period: 1-year longitudinal study

The aim of this study was to determine whether soccer could have different bone benefits in prepubescent and pubescent boys. We investigated 76 boys aged 10 to 13 years during a 1-year study. All boys were prepubescent at the beginning of the study (T0); pubescent status was determined by a complete 24-h urine hormonal assay of FSH-LH, with LH ≤ 0.31 IU/24 h and FSH ≤ 2.19 IU/24 h corresponding to prepubescent Tanner stage I and with 0.31 < LH < 0.95 IU/24 h and 1.57 < FSH < 3.77 IU/24 h corresponding to pubescent Tanner stage II. At the end of the study (T1), 35 boys remained prepubescent (22 soccer players (F1) and 13 controls (C1)), and 41 boys had entered puberty (26 soccer players (F2) and 15 controls (C2)). Soccer players completed 2 to 5 h of training plus one competition game per week during the school year, and controls only had physical education at school. Bone mineral content (BMC) was measured at T0 and T1 by DPX in the lumbar spine, total hip, and whole body (WB) for a comparison between soccer players and controls. At T0, no BMC difference was found between F1 and C1, but BMC was higher in F2 than C2 in WB and weight-bearing sites. At T1, BMC was higher in WB and weight-bearing sites in both F1 and F2 compared to their respective controls. Between T0 and T1, soccer induced a BMC gain at weight-bearing sites in both F1 and F2 compared to C1 and C2, respectively. The soccer-related bone gain was greater in WB and weight-bearing (the lumbar spine, total hip, and supporting leg) and non-weight-bearing bones (dominant arm and nondominant arm) in boys who became pubescent than in boys who remained prepubescent. In conclusion, 1-year study in young male soccer players demonstrates that the process of bone accretion at the very early phase of puberty is more intensely stimulated by the combination of physical exercise and sexual impregnation than by one of these factors alone.

Enhanced bone mass and physical fitness in prepubescent basketball players

The aim of this study was to examine the effect of basketball practice on bone acquisition in the prepubertal age. In total, 48 prepubescent male basketball players aged 11.1 ± 0.8 yr, Tanner stage 1, were compared with 50 controls matched for age and pubertal stage. Areal bone mineral density, bone mineral content (BMC), and bone area (BA) in deferent sites associated with anthropometric parameters were measured by dual-energy X-ray absorptiometry. Running and jumping tests were performed. Analysis of Student's impaired t-test revealed that basketball players attained better results in all physical fitness tests (p < 0.05). They also exhibited significantly greater BMC and BA in whole body, upper and lower extremities, trochanter, total hip, and whole right and left radius (p < 0.001) compared with the controls. No significant differences were observed between groups in right and left ultradistal and third distal radius and spinal regions, BMC, and BA, whereas a significant positive correlation was reported between lean mass, BMC, and BA of lower limbs. In summary, basketball practice in prepubertal age is associated with improved physical fitness and enhanced lean and bone mass in loaded sites.

Can physical activity improve peak bone mass?

The pediatric origin of osteoporosis has led many investigators to focus on determining factors that influence bone gain during growth and methods for optimizing this gain. Bone responds to bone loading activities by increasing mass or size. Overall, pediatric studies have found a positive effect of bone loading on bone size and accrual, but the types of loads necessary for a bone response have only recently been investigated in human studies. Findings indicate that responses vary by sex, maturational status, and are site-specific. Estrogen status, body composition, and nutritional status also may influence the bone response to loading. Despite the complex interrelationships among these various factors, it is prudent to conclude that increased physical activity throughout life is likely to optimize bone health.

Specific bone mass acquisition in elite female athletes

CONTEXT

Cross-sectional studies have demonstrated that physical activity can improve bone mass acquisition. However, this design is not adequate to describe the specific kinetics of bone mass gain during pubertal development.

OBJECTIVE

To compare the kinetics of bone mass acquisition in female adolescent athletes of sports that impose different mechanical loads and untrained controls throughout puberty.

STUDY PARTICIPANTS

A total of 72 girls with ages ranging from 10.8 to 18.0 years were recruited: 24 rhythmic gymnasts (RG, impact activity group), 24 swimmers (SW, no-impact activity), and 24 age-matched controls (CON).

MAIN OUTCOME MEASURES

Areal bone mineral density (aBMD) was determined using dual-energy x-ray absorptiometry and bone turnover markers were analyzed. All the investigations were performed at baseline and after 1 year.

RESULTS

At baseline and after 1 year of follow-up, RG presented significantly greater aBMD adjusted for age, fat-free soft tissue, and fat mass compared with CON and SW, only at the femoral region. When aBMD variation throughout the pubertal period was modeled for each group from individual values, the aBMD at the femoral region was significantly higher in RG compared with the other 2 groups from 12.5 to 14 years, and this difference lasted up to 18 years. Moreover, the mean annual aBMD gain tended to be higher in RG compared with SW and CON only at the femoral region and this gain lasted longer in RG. Bone remodeling markers decreased similarly with age in the 3 groups.

CONCLUSIONS

This study, which was based on linear mixed models for longitudinal data, demonstrated that the osteogenic effect of gymnastics is characterized by greater bone mass gain localized at mechanically loaded bone (ie, the proximal femur) principally around the menarcheal period. Moreover, the bone mass gain lasts longer in gymnasts, which may be explained by the delay in sexual maturation.

Proximal humeral fracture fixation: a biomechanical comparison of two constructs

BACKGROUND

Different options exist for stabilizing proximal humeral fractures. This study compared the mechanical stability of 2 common proximal humeral fixation plates in bending and torsion.

METHODS

Tests were conducted on 40 synthetic and 10 matched pairs of cadaveric humeri (evenly fixed with DePuy S3 proximal humeral plating system [DePuy Orthopaedics, Warsaw, IN, USA] and Synthes proximal humerus locking compression plate [Synthes, Paoli, PA, USA]). Half of the humeri were tested by cantilevered bending in flexion, extension, varus, and valgus for 100 cycles of ±5 mm of displacement at 1 mm/s before loading to failure in varus. The other half were tested in torsion for 100 cycles of ±8° of rotational displacement at 1°/s before loading to failure in external rotation.

RESULTS

Peak cyclic loads for synthetic constructs were higher for DePuy plates than Synthes plates in varus and valgus (P < .0001), but a difference was not detected in extension (P > .40) or flexion (P = .0675). Peak cyclic loads for cadaveric constructs showed a significant difference in extension and flexion (Synthes > DePuy, P < .0001) and in varus (DePuy > Synthes, P < .05) but not in valgus (P > .10). Bending stiffness during varus failure testing was higher for DePuy plates than Synthes plates (P < .0001) for synthetic constructs. Regarding torsion of synthetic and cadaveric constructs, DePuy plates experienced higher peak cyclic torques over all cycles in both directions (P < .0001). For synthetic constructs, DePuy plates showed higher torsional stiffness in external failure than Synthes plates (P < .0001).

CONCLUSIONS

The DePuy plate was stiffer than the Synthes plate with varus and valgus bending, as well as in torsion. The Synthes plate tended to be stiffer in flexion and extension.

Aggravation of inflammatory response by costimulation with titanium particles and mechanical perturbations in osteoblast- and macrophage-like cells

The interface between bone tissue and metal implants undergoes various types of mechanical loading, such as strain, compression, fluid pressure, and shear stress, from daily activities. Such mechanical perturbations create suboptimal environments at the host bone-implant junction, causing an accumulation of wear particles and debilitating osseous integration, potentially leading to implant failure. While many studies have focused on the effect of particles on macrophages or osteoprogenitor cells, differential and combined effects of mechanical perturbations and particles on such cell types have not been extensively studied. In this study, macrophages and osteoprogenitor cells were subjected to physiological and superphysiological mechanical stimuli in the presence and absence of Ti particles with the aim of simulating various microenvironments of the host bone-implant junction. Macrophages and osteoprogenitor cells were capable of engulfing Ti particles through actin remodeling and also exhibited changes in mRNA levels of proinflammatory cytokines under certain conditions. In osteoprogenitor cells, superphysiological strain increased proinflammatory gene expression; in macrophages, such mechanical perturbations did not affect gene expression. We confirmed that this phenomenon in osteoprogenitor cells occurred via activation of the ERK1/2 signaling pathway as a result of damage to the cytoplasmic membrane. Furthermore, AZD6244, a clinically relevant inhibitor of the ERK1/2 pathway, mitigated particle-induced inflammatory gene expression in osteoprogenitor cells and macrophages. This study provides evidence of more inflammatory responses under mechanical strains in osteoprogenitor cells than macrophages. Phagocytosis of particles and mechanical perturbation costimulate the ERK1/2 pathway, leading to expression of proinflammatory genes.

Skeletal effects of long-term caloric restriction in rhesus monkeys

Age-related bone loss is well established in humans and is known to occur in nonhuman primates. There is little information, however, on the effect of dietary interventions, such as caloric restriction (CR), on age-related bone loss. This study examined the effects of long-term, moderate CR on skeletal parameters in rhesus monkeys. Thirty adult male rhesus monkeys were subjected to either a restricted (R, n = 15) or control (C, n = 15) diet for 20 years and examined throughout for body composition and biochemical markers of bone turnover. Total body, spine, and radius bone mass and density were assessed by dual-energy X-ray absorptiometry. Assessment of biochemical markers of bone turnover included circulating serum levels of osteocalcin, carboxyterminal telopeptide of type I collagen, cross-linked aminoterminal telopeptide of type I collagen, parathyroid hormone, and 25(OH)vitamin D. Overall, we found that bone mass and density declined over time with generally higher levels in C compared to R animals. Circulating serum markers of bone turnover were not different between C and R with nonsignficant diet-by-time interactions. We believe the lower bone mass in R animals reflects the smaller body size and not pathological osteopenia.

Bone health: part 2, physical activity

Mechanical loading is a crucial factor for maintaining skeletal health. Physical activities, exercise, and sports provide a wealth and variety of mechanical loads to bones, through muscle forces, ground reaction forces, and other contact or impact forces. Weightbearing activities can be effective exercises to enhance bone health-particularly, those that involve jumping and impact loads (with greater strain magnitudes, rates, and frequencies). Physical activity appears to be acutely beneficial for enhancing bone health in the early pubertal period and in older age, such as in postmenopausal women. In preparing this article, PubMed, Web of Science, and relevant edited books (English language) were reviewed from 1961 to present.

Bone mineral density and body composition of South African cricketers

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