Adaptive skeletal responses to mechanical loading during adolescence

Skeletal Loading: Lean and Bone Mass Development in Young Elite Male Gymnasts, Swimmers, and Nonathletes Aged 6-24 Years

BACKGROUND

Exercise optimizes peak bone mass accrual, particularly if the loading is high magnitude and distributed in abnormal directions. Little is known about the influence of early intense training in sport during peak bone mass accrual, especially in boys.

METHODS

Ninety-eight males aged 6-24 years (gymnasts, swimmers, and controls) completed the bone-specific physical activity questionnaire and a 7-day exercise diary. Dual-energy X-ray absorptiometry determined bone mineral properties of the total body (less head) and lumbar spine (LS, L1-L4) and total lean mass. Subgroup analyses were conducted for juniors (prepubescent), adolescents (11-16 y), and seniors (17-24 y).

RESULTS

Lean mass was positively associated with total body less head and LS bone outcomes in all 3 age groups (R2 = .632-.770, P < .05), and bone-specific physical activity questionnaire scores were associated with LS bone mineral density in adolescents and seniors (R2 = .440 and .591, P < .05). Senior gymnasts had significantly higher LS bone mineral density (in grams per square centimeter) and Z-scores than swimmers (P = .004) and controls (P = .012).

CONCLUSIONS

Elite gymnastics is associated with superior peak bone mass accrual in young males. The benefits appear more pronounced during young adulthood compared with prepuberty, potentially reflecting an extended time course for bone adaptation.

The relationship between muscle thickness and pennation angle is mediated by fascicle length in the muscles of the lower extremities

Muscle morphological architecture, a crucial determinant of muscle function, has fascinated researchers since the Renaissance. Imaging techniques enable the assessment of parameters such as muscle thickness (MT), pennation angle (PA), and fascicle length (FL), which may vary with growth, sex, and physical activity. Despite known interrelationships, robust mathematical models like causal mediation analysis have not been extensively applied to large population samples. We recruited 109 males and females, measuring knee flexor and extensor, and plantar flexor MT, PA, and FL using real-time ultrasound imaging at rest. A mixed-effects model explored sex, leg (dominant vs. non-dominant), and muscle region differences. Males exhibited greater MT in all muscles (0.1 to 2.1 cm, p < 0.01), with no sex differences in FL. Dominant legs showed greater rectus femoris (RF) MT (0.1 cm, p = 0.01) and PA (1.5°, p = 0.01), while vastus lateralis (VL) had greater FL (1.2 cm, p < 0.001) and PA (0.6°, p = 0.02). Regional differences were observed in VL, RF, and biceps femoris long head (BFlh). Causal mediation analyses highlighted MT's influence on PA, mediated by FL. Moderated mediation occurred in BFlh, with FL differences. Gastrocnemius medialis and lateralis exhibited FL-mediated MT and PA relationships. This study unveils the intricate interplay of MT, FL, and PA in muscle architecture.

Impact of leptin deficiency on male tibia and vertebral body 3D bone architecture independent of changes in body weight

Leptin an adipokine with potent effects on energy balance and body weight plays an important role in defining bone architecture in growing mammals. However, major changes in body weight can also influence morphology of trabecular and cortical bone. Therefore, we examined the impact of leptin deficiency on tibia and vertebral body 3D bone architecture independent of changes in body weight. Furthermore, advances in computational 3D image analysis suggest that average morphological values may mask regional specific differences in trabecular bone thickness. The study utilized leptin-deficient Ob/Ob mice (n = 8) weight-paired to C57BL/6 (C57) control mice (n = 8) which were split into either lean or obese groups for 24 ± 2 weeks. Whole tibias and L3 vertebrae were fixed before high resolution microcomputed tomography (μCT) scanning was performed. Leptin deficiency independent of body weight reduced tibia cortical bone volume, trabecular bone volume/tissue volume, number, and mineral density. Mean tibia trabecular thickness showed no significant differences between all groups; however, significant changes in trabecular thickness were found when analyzed by region. This study demonstrates that leptin deficiency significantly impacts tibia and vertebral body trabecular and cortical bone 3D architecture independent of changes in body weight.

Association between bone mineral density and content and physical growth parameters among children and adolescents diagnosed with HIV: a cross-sectional study

BACKGROUND

During childhood and adolescence, there are significant increases in bone mineral content (BMC) and bone mineral density (BMD).

OBJECTIVE

To investigate physical growth parameters associated with BMD and BMC among children and adolescents diagnosed with human immunodeficiency virus (HIV).

DESIGN AND SETTING

Cross-sectional study conducted in Florianópolis, Brazil, among 63 children and adolescents (aged 8-15 years) diagnosed with HIV.

METHOD

BMD, BMC and fat percentage z score were evaluated using dual X-ray absorptiometry. Age/height z score and body mass index (BMI)/age z score were obtained in accordance with international recommendations, and bone age was obtained through hand-wrist radiography. Sex, family income, information on HIV infection (T CD4+ lymphocyte count, viral load and type of antiretroviral therapy, moderate-vigorous physical activity and sedentary behavior) were used as adjustment variables in the analyses. Simple and multiple linear regression analyses were performed, with a significance level of P ≤ 0.05.

RESULTS

Subtotal BMD (without the head region) was directly associated with bone age, BMI/age z score and fat percentage z score, even after adjusting for covariates. Subtotal BMC/height was directly associated with bone age, height/age z score, BMI/age z score and fat percentage z score, even after adjusting for covariates.

CONCLUSION

Subtotal BMD and subtotal BMC/height were directly associated with physical growth indicators among children and adolescents diagnosed with HIV.

Bone Geometry Is Altered by Follistatin-Induced Muscle Growth in Young Adult Male Mice

The development of the musculoskeletal system and its maintenance depends on the reciprocal relationship between muscle and bone. The size of skeletal muscles and the forces generated during muscle contraction are potent sources of mechanical stress on the developing skeleton, and they shape bone structure during growth. This is particularly evident in hypermuscular global myostatin (Mstn)‐null mice, where larger muscles during development increase bone mass and alter bone shape. However, whether muscle hypertrophy can similarly influence the shape of bones after the embryonic and prepubertal period is unknown. To address this issue, bone structure was assessed after inducing muscle hypertrophy in the lower hindlimbs of young‐adult C57BL/6J male mice by administering intramuscular injections of recombinant adeno‐associated viral vectors expressing follistatin (FST), a potent antagonist of Mstn. Two FST isoforms were used: the full‐length 315 amino acid isoform (FST‐315) and a truncated 288 amino acid isoform (FST‐288). In both FST‐treated cohorts, muscle hypertrophy was observed, and the anterior crest of the tibia, adjacent to the tibialis anterior muscle, was lengthened. Hypertrophy of the muscles surrounding the tibia caused the adjacent cortical shell to recede inward toward the central axis: an event driven by bone resorption adjacent to the hypertrophic muscle. The findings reveal that inducing muscle hypertrophy in mice can confer changes in bone shape in early adulthood. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Protocol of a randomised controlled trial assessing the impact of physical activity on bone health in children with inflammatory bowel disease

INTRODUCTION

Low bone mineral density (BMD) is a frequent issue in children and adolescents with inflammatory bowel disease (IBD). Several studies in healthy populations have reported a positive impact of physical activity (PA) on bone health. Recently, an observational study in paediatric patients with IBD showed a significant positive relationship between daily PA and BMD. However, intervention studies investigating a causal relationship between PA and BMD are warranted to confirm these results. The aim of this randomised controlled trial will be to investigate the effect of a PA programme on BMD in paediatric patients with IBD.

METHODS AND ANALYSIS

This trial is a multicentre (four centres), randomised, controlled, blinded end-point study. Eighty children with IBD will be randomly assigned in a 1:1 ratio to receive a programme with adapted physical exercises (intervention group) or usual PA (control group) during a 9-month period. The primary outcome is the change from baseline at 9 months (the end of the study) in whole-body BMD assessed by dual-energy X-ray absorptiometry. Secondary efficacy outcomes include the changes from baseline at 9 months in: BMD assessed in the lumbar spine and trochanter; daily PA (time spent in moderate-to-vigorous PA); body composition (fat mass and fat-free mass); fatigue resistance; quality of life and activity of IBD.

ETHICS AND DISSEMINATION

The study was approved by the Research Ethics Committee in France (Comité de Protection des Personnes, Sud-Ouest and Outre-Mer III, Bordeaux, France, No 2018/27). All procedures will be performed according to the ethical standards of the Helsinki Declaration of 1975, as revised in 2008, and the European Union's Guidelines for Good Clinical Practice. Written informed consent will be obtained from the parents or legal guardian and from the children. Research findings will be disseminated in peer-reviewed journals and scientific meetings.

TRIAL REGISTRATION NUMBER

NCT03774329.

An Overview of the Beneficial Effects of Exercise on Health and Performance

Life expectancy is steadily increasing in modern societies, and so are noncommunicable diseases such as cardiovascular diseases, diabetes, obesity, and cancer, accounting for more than 70% of all deaths globally. The costs associated with these diseases are enormous, but it has been estimated that the majority of these noncommunicable diseases are preventable. In addition to an unhealthy diet, tobacco use, and harmful use of alcohol, physical inactivity is a key risk factor. Consequently, physical activity is a logical remedy, and in this chapter an overview of the numerous beneficial effects of physical activity on health and performance is given.The chapter is divided into three parts: First, the basics of physical activity and exercise are discussed, for instance exercise classification, exercise intensity operationalization, energy supply, and the acute effects of exercise such as blood flow redistribution and increased cardiac output. In the second part, the effects of exercise on physical performance are summarized. Specifically, it is discussed how endurance, strength, power, and balance can be improved. This discussion includes recommendations regarding the type, intensity, and duration of the exercise leading to improvements in one of these aspects of physical performance, as well as the mechanisms causing these adaptations. In the third part, the beneficial effects of physical activity on physical and mental health are outlined, with particular attention to cardiovascular diseases, the metabolic syndrome, musculoskeletal diseases, mood, anxiety, depression, and dementia.It can be concluded that with adequate programming, regular physical activity is an effective way to improve physical performance, improve physical and mental health, and reduce the risk factors for many noncommunicable diseases such as cardiovascular diseases, metabolic syndrome, sarcopenia, osteoporosis, and depression. In contrast to medication, physical exercise has no negative side effects, costs very little, and targets many health issues at once. If the multitude of beneficial effects of regular exercise were to be combined in a single low-cost drug, it would be prescribed for almost all types of physical and mental health issues.

Body Weight and Body Mass Index Influence Bone Mineral Density in Late Adolescence in a Two-Year Follow-Up Study. The Tromsø Study: Fit Futures

Determinants of bone acquisition in late adolescence and early adulthood are not well‐described. This 2‐year follow‐up study explored the associations of body weight (BW), body mass index (BMI), and changes in weight status with adolescent bone accretion in a sample of 651 adolescents (355 girls and 296 boys) between 15 and 19 years of age from The Tromsø Study: Fit Futures. This Norwegian population‐based cohort study was conducted from 2010 to 2011 and was repeated from 2012 to 2013. We measured femoral neck, total hip, and total body bone mineral content and areal bone mineral density (aBMD) by dual‐energy X‐ray absorptiometry. We measured height, BW, calculated BMI (kg/m ²), and collected information on lifestyle at both surveys. Mean BMI (SD) at baseline was 22.17 (3.76) and 22.18 (3.93) in girls and boys, respectively. Through multiple linear regression, baseline BW and BMI were positively associated with ∆aBMD over 2 years of follow‐up at all skeletal sites in boys ( p < 0.05), but not in girls. ∆BW and ∆BMI predicted ∆aBMD and ∆BMC in both sexes, but the strength of the associations was moderate. Individuals who lost weight during follow‐up demonstrated a slowed progression of aBMD accretion compared with those gaining weight, but loss of BW or reduction of BMI during 2 years was not associated with net loss of aBMD. In conclusion, our results confirm that adequate BW for height in late adolescence is important for bone health. Associations between change in weight status and bone accretion during follow‐up were moderate and unlikely to have any clinical implication on adolescents of normal weight. Underweight individuals, particularly boys, are at risk of not reaching optimal peak bone mass and could benefit from an increase in BMI. © 2019 The Authors. JBMR Plus is published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research.

EFFECTS OF COMBAT SPORTS ON BONE MASS: SYSTEMATIC REVIEW

ABSTRACT Objective To determine the influence of combat sports on bone mass. Methods A systematic review was performed according to the PRISMA method, with searches in the Pubmed, Bireme, Embase and Web of Science databases covering the period 1900 to 2015, using the keywords “martial arts”, “fight”, “combat”, “karate”, “kung fu”, “tae kwon do”, “judo”, “aikido”, “bone mass”, “bone health”, “bone tissue”, “bone density”, and “bone mineral contents”. The articles were searched for and retrieved electronically and manually, by two independent reviewers. Results Seventy-nine articles were identified, of which 25 were duplicates, leaving 54 for reading and evaluation of the titles; next, articles about diseases such as bone and/or orthopedic injuries, maxillofacial, surgeries, fractures, osteoporosis and osteopenia in women, prevention of falls, and physical fitness were excluded, leaving 15 articles. Of the articles selected and retrieved in full, all were published between 2002 and 2015. One article was a case control study; two were longitudinal studies, two were randomized studies; and 10 were cross-sectional studies. A total of 1368 children, adolescents, adults and elderly subjects were involved in combat sports and had bone evaluation by imaging. Factors such as calorie intake, calcium and/or vitamin D, intensity and volume of the exercise, hormonal aspects as bone markers, and characteristics of menopause are not conclusive in relation to bone mass, and further studies are needed. Conclusion The practice of combat sports shows a significant improvement in bone mass at all ages. Level of Evidence III, Therapeutic study – Investigation of treatment results.

Judo Practice in Early Age Promotes High Level of Bone Mass Acquisition of Growing Boys' Skeleton

The current study aimed to exhibit effects of judo training for at least 2 yr on bone mass parameters in growing boys. Our population was composed of one hundred and thirty boys in tanner stage 1 and aged 10.52 ± 0.86 yr. Eleven judo players were therefore, excluded from the study because they do not have participate regularly to the judo training sessions during the last 2 yr. The resting sample was divided into two groups: 50 judo players (JU group) and 69 controls (C group). Bone mineral density (BMD), bone mineral content (BMC), and bone area (BA) were evaluated by using dual-photon X-ray absorptiometry on weight-bearing sites: the whole body, lumbar spine (L2-L4), legs, femoral necks and hips and on the non-weight bearing sites: arms and radiuses. Our findings displayed that judo participation was markedly associated with greater values of bone mass parameters in young judo players than control group. Accordingly, the BMD and BA results exhibited significant differences in the whole body, legs, dominant total hip, arms and both whole radiuses in addition to the dominant femoral neck, the non-dominant total hip and except the non-dominant whole radius for the BMC parameter. Additionally, data of the subject within t test has shown significant differences of bone mass parameters only in the non weight-bearing sites in the judo players without any obvious variation in the controls. Differences of BMD observed on the dominant arm and whole radius in addition to the increased BMC values showed in the dominant whole radius compared with their contra-lateral sites in judo players without any marked variation of BA parameters in all sites in both groups. In growing boys, judo practice was obviously associated with osteogenic effects in specific sites.

Bone mineral density in pre-professional female ballet dancers: A systematic review and meta-analysis

OBJECTIVES

To quantitatively compare bone mineral density (BMD) outcomes between pre-professional female adolescent ballet dancers and control populations.

DESIGN

Systematic review and meta-analysis.

METHODS

Six electronic databases and relevant journals were systematically searched up to August 2017. Included articles examined BMD in adolescent females undergoing pre-professional ballet training and healthy age-matched controls with an available English full text. Dancers were aged 15-19 years and trained in ballet at least 10h per week. BMD data were analysed via standardized mean difference to account for differences in reporting methods RESULTS: From 3984 potential articles, 8 cross-sectional studies were accepted for inclusion, which compared 293 dancers (16.9±0.8 years) to 333 controls (16.9±0.9 years). No data were available from longitudinal studies. Dancers displayed lower BMD at the radius and higher BMD at the femoral neck, femoral trochanter and Ward's triangle. No significant differences were observed in the lumbar spine or tibia. The overall study quality was low and heterogeneity was present in some analyses.

CONCLUSIONS

This meta-analysis indicates that there may be a site-specific osteogenic effect of pre-professional classical ballet training in adolescent females, with a notable and concerning finding of reduced upper limb BMD compared to age-matched controls. Longitudinal cohort studies are required to confirm the effects of pre-professional ballet training on BMD during adolescence.

Bone mineral density at the hip and its relation to fat mass and lean mass in adolescents: the Tromsø Study, Fit Futures

Background

Positive association between body weight and bone mass is well established, and the concept of body mass index (BMI) is associated with higher areal bone mineral density (aBMD) and reduced fracture risk. BMI, that comprises both fat mass (FM) and lean mass (LM) may contribute to peak bone mass achievement in different ways. This study explored the influence of body composition in terms of total body LM and FM on hip aBMD-values in adolescence.

Methods

In 2010/2011, 93% of the region’s first-year upper-secondary school students (15–17 years old) in Tromsø, Norway attended the Tromsø Study, Fit Futures. Areal BMD at femoral neck (aBMD_FN) and total hip (aBMD_TH) (g/cm²), total body LM and FM (g) were measured by dual energy X-ray absorptiometry (DXA). Height and weight were measured, and BMI calculated. Lifestyle variables were collected by self-administered questionnaires and interviews, including questions on time spent on leisure time physical activity. Stratified analyses of covariance and regression models included 395 girls and 363 boys. Crude results were adjusted for age, height, sexual maturation, physical activity levels, vitamin D levels, calcium intake, alcohol consumption and smoking habits.

Results

Unadjusted distribution indicated higher aBMD-levels at higher LM-levels in both genders (p < 0.001), but higher aBMD at higher FM-levels were found only in girls (p < 0.018). After multiple adjustments, aBMD_FN-levels in girls were associated by 0.053 g/cm² and 0.032 g/cm² per standard deviation (SD) change in LM and FM (p < 0.001). Corresponding values in boys were 0.072 and 0.025 (p < 0.001). The high LM groups accounted for the highest aBMD-levels, while aBMD-levels at the LM/FM-combinations indicated different patterns in girls compared to boys. The adjusted odds ratio (95% CI) for low levels of aBMD_FN was 6.6 (3.4,13.0) in boys, compared to 2.8 (1.6,4.9) in girls per SD lower LM.

Conclusions

LM and FM should be regarded as strong predictors for bone mass and hence bone strength in adolescents. A gender specific difference indicated that high lean mass is of crucial importance prominently in boys. In adolescents with low lean mass, especially in girls, high fat mass may partially ameliorate the effect of deficient lean mass levels.

Longitudinal Adaptations of Bone Mass, Geometry, and Metabolism in Adolescent Male Athletes: The PRO-BONE Study

Adolescence is a crucial period for bone development, and exercise can enhance bone acquisition during this period of life. However, it is not known how the different loading sports practiced can affect bone acquisition in adolescent male athletes. Therefore, the purpose of the present study was to determine the 1-year longitudinal bone acquisition among adolescent males involved in osteogenic (football) and non-osteogenic (swimming and cycling) sports and to compare with active controls. A total of 116 adolescent males aged 12 to 14 years at baseline were followed for 1 year: 37 swimmers, 37 footballers, 28 cyclists, and 14 active controls. Bone mineral content (BMC) was assessed using dual-energy X-ray absorptiometry (DXA); cross-sectional area (CSA), cross-sectional moment of inertia (CSMI), and section modulus (Z) at the femoral neck was assessed using hip structural analysis (HSA); and bone texture of the lumbar spine was assessed using trabecular bone score (TBS). Serum N-terminal propeptide of procollagen type I (PINP), isomer of the Carboxi-terminal telopeptide of type 1 collagen (CTX-I), total serum calcium, and 25 hydroxyvitamin D [25(OH)D] were analyzed. Footballers had significantly higher adjusted BMC at the lumbar spine (7.0%) and femoral neck (5.0%) compared with cyclists, and significantly greater BMC at the lumbar spine (6.9%) compared with swimmers. Footballers presented significantly greater TBS (4.3%) compared with swimmers, and greater CSMI (10.2%), CSA (7.1%), Z (8.9%) and TBS (4.2%) compared with cyclists. No differences were noted between cyclists and swimmers, both groups had similar bone acquisition compared with controls. PINP was significantly higher in footballers and controls compared with cyclists and swimmers (3.3% to 6.0%), and 25(OH)D was significantly higher in footballers and cyclists compared with swimmers and controls (9.9% to 13.1%). These findings suggest that bone acquisition is higher in adolescent male footballers compared with swimmers and cyclists at the femoral neck and lumbar spine sites of the skeleton. © 2017 American Society for Bone and Mineral Research.

BONE MASS BY QUANTITATIVE ULTRASOUND OF FINGER PHALANGES IN YOUNG KARATE PRACTITIONERS

Objective:

To evaluate bone mass by quantitative ultrasound of the phalanges in young karate practitioners compared to a control group.

Methods:

Sample composed of 162 karate practitioners (52 females) and 326 healthy controls (110 females) aged 6 to 16 years old, in Western Paraná (Southern Brazil). Weight, height, BMI, amplitude-dependent speed of sound (AD-SoS) and bone transmission time (BTT) were evaluated. BMI, AD-SoS and BTT values were converted to Z scores. Mann-Whitney, chi-square or Fisher Exact tests and multiple linear regression were applied, with significance level set at p≤0.05.

Results:

Both genders showed higher values of BTT as Z scores when compared to control group. Females from the control group had higher AD-SoS values (m/s and Z score) compared to female karate practitioners. When relative and absolute frequencies were assessed according to BTT Z score in both groups, male karate practitioners’ bone mass was shown to be adequate more frequently. In female practitioners, age and weight were independent predictors of AD-SoS (R²=0.42) and BTT (R²=0.45), respectively. Among male karate practitioners, age was related to 26% of AD-SoS variances and height was responsible for 36% of BTT variances.

Conclusions:

Children and adolescents who practice karate were shown to have more bone mass in comparison to the control group, regardless of gender. BTT was more sensitive for this evaluation.

Bone mineral density in vocational and professional ballet dancers

According to existing literature, bone health in ballet dancers is controversial. We have verified that, compared to controls, young female and male vocational ballet dancers have lower bone mineral density (BMD) at both impact and non-impact sites, whereas female professional ballet dancers have lower BMD only at non-impact sites.

INTRODUCTION

The aims of this study were to (a) assess bone mineral density (BMD) in vocational (VBD) and professional (PBD) ballet dancers and (b) investigate its association with body mass (BM), fat mass (FM), lean mass (LM), maturation and menarche.

METHODS

The total of 152 VBD (13 ± 2.3 years; 112 girls, 40 boys) and 96 controls (14 ± 2.1 years; 56 girls, 40 boys) and 184 PBD (28 ± 8.5 years; 129 females, 55 males) and 160 controls (27 ± 9.5 years; 110 female, 50 males) were assessed at the lumbar spine (LS), femoral neck (FN), forearm and total body by dual-energy X-ray absorptiometry. Maturation and menarche were assessed via questionnaires.

RESULTS

VBD revealed lower unadjusted BMD at all anatomical sites compared to controls (p < 0.001); following adjustments for Tanner stage and gynaecological age, female VBD showed similar BMD values at impact sites. However, no factors were found to explain the lower adjusted BMD values in VBD (female and male) at the forearm (non-impact site), nor for the lower adjusted BMD values in male VBD at the FN. Compared to controls, female PBD showed higher unadjusted and adjusted BMD for potential associated factors at the FN (impact site) (p < 0.001) and lower adjusted at the forearm (p < 0.001). Male PBD did not reveal lower BMD than controls at any site.

CONCLUSIONS

Both females and males VBD have lower BMD at impact and non-impact sites compared to control, whereas this is only the case at non-impact site in female PBD. Maturation seems to explain the lower BMD at impact sites in female VBD.

Changes and tracking of bone mineral density in late adolescence: the Tromsø Study, Fit Futures

Areal bone mineral density (aBMD) predicts future fracture risk. This study explores the development of aBMD and associated factors in Norwegian adolescents. Our results indicate a high degree of tracking of aBMD levels in adolescence. Anthropometric measures and lifestyle factors were associated with deviation from tracking.

PURPOSE

Norway has one of the highest reported incidences of hip fractures. Maximization of peak bone mass may reduce future fracture risk. The main aims of this study were to describe changes in bone mineral levels over 2 years in Norwegian adolescents aged 15-17 years at baseline, to examine the degree of tracking of aBMD during this period, and to identify baseline predictors associated with positive deviation from tracking.

METHODS

In 2010-2011, all first year upper secondary school students in Tromsø were invited to the Fit Futures study and 1038 adolescents (93%) attended. We measured femoral neck (FN), total hip (TH), and total body (TB) aBMD as g/cm² by DXA. Two years later, in 2012-2013, we invited all participants to a follow-up survey, providing 688 repeated measures of aBMD.

RESULTS

aBMD increased significantly (p < 0.05) at all skeletal sites in both sexes. Mean annual percentage increase for FN, TH, and TB was 0.3, 0.5, and 0.8 in girls and 1.5, 1.0, and 2.0 in boys, respectively (p < 0.05). There was a high degree of tracking of aBMD levels over 2 years. In girls, several lifestyle factors predicted a positive deviation from tracking, whereas anthropometric measures appeared influential in boys. Baseline z-score was associated with lower odds of upwards drift in both sexes.

CONCLUSIONS

Our results support previous findings on aBMD development in adolescence and indicate strong tracking over 2 years of follow-up. Baseline anthropometry and lifestyle factors appeared to alter tracking, but not consistently across sex and skeletal sites.

Effects of maturation on combined female muscle strength and ACL structural factors

OBJECTIVES

Relations between lower limb muscle strength and female ACL injury risk are well documented. How these relations combine with key ACL geometries however, is unknown. Identifying how these combined factors are impacted by maturation would benefit current risk screening and prevention efforts. This study compared hamstrings and quadriceps strength and ACL cross sectional area (CSA) indices across three maturation groups.

DESIGN

Cross-sectional human experimental.

METHODS

MRI scans of the dominant knee were collected in 35 females stratified into early (9.7±0.8yrs), middle (12.9±1.7yrs), and late (14.8±0.6yrs) maturation groups. Hamstring and quadriceps muscle volumes and ACL CSA measures were obtained. Isokinetic strength data were quantified for dominant knee flexors and extensors. Peak hamstring and quadriceps concentric and eccentric strength per unit volume magnitudes (QCSPV, HCSPV, QESPV, HESPV) were determined. Metrics and select ratios were submitted to a one way ANOVA to determine the main effect of maturation.

RESULTS

Significant decreases occurred in HESPV (N/cm(3)) and ACL CSA (cm(2)/kgm), respectively, from early (0.188±0.023N/cm(3), 0.007±0.002cm(2)/kgm) to middle (0.157±0.029N/cm(3), 0.005±0.002cm(2)/kgm, p=0.034, p=0.029), and middle to late (0.132±0.031N/cm(3), 0.003±0.001cm(2)/kgm, p=0.044, p=0.018) maturation. A significant decrease in HESPV:QCSPV occurred between early (1.795±0.496) and middle (1.362±0.277, p=0.018) maturation.

QCSPV

ACL CSA was significantly greater in late (37.26±13.35) compared to middle (25.81±9.17, p=0.021) maturation.

CONCLUSIONS

Key ratios between female knee quadriceps and hamstring strength and ACL size parameters, which may directly impact ACL injury risk, are substantially different among three maturation states. The results are potentially hazardous strength mismatches in mid-pubertal females, where a smaller (weaker) ACL may be unable to stabilize quadriceps dominated loading strategies.

Prevalence of low bone mineral density in female dancers

BACKGROUND AND OBJECTIVE

While some authors report that dancers have reduced bone mineral density (BMD) and increased risk of osteoporosis, others have stressed the positive effects of dance training on developing healthy BMD. Given the existing controversy, the aim of this systematic review was to examine the best evidence-based information available in relation to female dancers.

METHODS

Four databases (Web of Science, PubMed, EBSCO, Scopus) and two dance science journals (Journal of Dance Medicine and Science and Medical Problems of Performing Artists) were searched for relevant material using the keywords "dance", "ballet", "BMD", "bone density", "osteoporosis" and "female athlete triad syndrome". A total of 257 abstracts were screened using selected inclusion (studies involving bone measurements in dancers) and exclusion (editorials, opinion papers, chapters in books, narrative reviews and non-English language papers) criteria according to PRISMA guidelines. Following the above screening, a total of 108 abstracts were identified as potentially relevant. After the exclusion of conference proceedings, review papers, studies focusing only in male dancers and studies in which dancers' information were combined with other athletes, the eligible papers were subsequently assessed using the GRADE system and grouped according to: (1) prevalence of low BMD and associated factors, (2) incidence of low BMD and risk factors, (3) prevention/treatment of low BMD in dancers, and (4) other studies.

RESULTS

Of the 257 abstracts that were initially screened, only 35 studies were finally considered. Only one of these 35 was of high quality, while the remaining 34 were of relatively low quality. Seven studies reported prevalence of low BMD and associated factors, 10 reported associated factors with no prevalence data, while one reported prevalence with no associated factors data. One study cited risk factors, while another one elaborated on the treatment of low BMD in dancers. The remaining 15 studies were classified as "other studies".

CONCLUSIONS

It remains unclear whether low BMD is prevalent in female dancers. The present review highlights the need for high-quality BMD research in this area.

Combat sports practice favors bone mineral density among adolescent male athletes

The aim of this study was to determine the impact of combat sports practice on bone mineral density (BMD) and to analyze the relationship between bone parameters and anthropometric measurements, bone markers, and activity index (AI). In other words, to detect the most important determinant of BMD in the adolescent period among combat sports athletes. Fifty athletes engaged in combat sports, mean age 17.1±0.2 yr, were compared with 30 sedentary subjects who were matched for age, height, and pubertal stage. For all subjects, the whole-body BMD, lumbar spine BMD (L2-L4), and BMD in the pelvis, arms, and legs was measured by dual-energy X-ray absorptiometry, and anthropometric measurements were evaluated. Daily calcium intake, bone resorption, and formation markers were measured. BMD measurements were greater in the combat sports athletes than in the sedentary group (p<0.01). Weight, body mass index, and lean body mass were significantly correlated with BMD in different sites. Daily calcium consumption lower than daily calcium intake recommended in both athletes and sedentary group. AI was strongly correlated with all BMD measurements particularly with the whole body, legs, and arms. Negative correlations were observed between bone markers and BMD in different sites. The common major predictor of BMD measurements was AI (p<0.0001). AI associated to lean body mass determined whole-body BMD until 74%. AI explained both BMD in arms and L2-L4 at 25%. AI associated to height can account for 63% of the variance in BMD legs. These observations suggested that the best model predicting BMD in different sites among adolescent combat sports athletes was the AI. Children and adolescents should be encouraged to participate in combat sports to maximize their bone accrual.

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.

Effects of weight-bearing exercise on bone health in girls: a meta-analysis

BACKGROUND

Because growing bone possesses a greater capacity to adapt to mechanical loading than does mature bone, it is important for girls to engage in weight-bearing activities, especially since the prevalence of osteoporosis among older women is considerably higher than that of older men. In recent years, the osteogenic potential of weight-bearing activities performed by children and adolescents has received increasing attention and accumulating evidence suggests that this type of activity may improve bone health prior to adulthood and help prevent osteoporosis later in life.

OBJECTIVE

Because previous interventions have varied with respect to the exercise parameters studied and sometimes produced conflicting findings, this meta-analysis was undertaken to evaluate the impact of weight-bearing exercise on the bone health of female children and adolescents and quantify the influence of key moderating variables (e.g. pubertal stage, exercise mode, intervention strategy, exercise duration, frequency of exercise, programme length and study design) on skeletal development in this cohort.

METHODS

A comprehensive literature search was conducted using databases such as PubMed, MEDLINE, CINAHL, Web of Science, Physical Education Index, Science Direct and ProQuest. Search terms included 'bone mass', 'bone mineral', 'bone health', 'exercise' and 'physical activity'. Randomized- and non-randomized controlled trials featuring healthy prepubertal, early-pubertal and pubertal girls and measurement of areal bone mineral density (aBMD) or bone mineral content (BMC) using dual energy x-ray absorptiometry were examined. Comprehensive Meta-Analysis software was used to determine weighted mean effect sizes (ES) and conduct moderator analyses for three different regions of interest [i.e. total body, lumbar spine (LS), and femoral neck].

RESULTS

From 17 included studies, 72 ES values were retrieved. Our findings revealed a small, but significant influence of weight-bearing exercise on BMC and aBMD of the LS (overall ES 0.19; 95% confidence interval (CI) 0.05, 0.33 and overall ES 0.26, 95% CI 0.09, 0.43, respectively) and BMC of the femoral neck (ES 0.23; 95% CI 0.10, 0.36). For both aBMD and BMC, overall ES was not affected by any moderator variables except frequency of exercise, such that weight-bearing activity performed for more than 3 days per week resulted in a significantly greater ES value for LS aBMD compared with programmes lasting 3 or fewer days per week [Cochran's Q statistic (Qbetween) = 4.09; p < 0.05].

CONCLUSION

The impact of weight-bearing activities seems to be site specific, and a greater frequency of weight-bearing activities is related to greater aBMD of LS in growing girls. Future investigations are warranted to better understand the dose-response relationship between weight-bearing activity and bone health in girls and explore the mediating role of pubertal status in promoting skeletal development among female youth.

Comparison of Bone Mineral Density among Alcoholism and Nonalcoholism Athlete and Nonathlete Subjects

BACKGROUND

The aim of this study was to compare bone mineral density among alcoholic, nonalcoholic and nonathlete subjects.

MATERIALS AND METHODS

The group consisted of physically active people. A questionnaire was given to both alcoholics and nonalcoholics and 28 persons were randomly selected (15 members who consumed alcohol and 13 who did not). In order to collect the data on mineral aggregation, a testing device (DEXA) was used. The data were analyzed using SPSS software.

RESULTS

It was found that higher bone aggregation in each of the two athletic group in comparison with the nonathletic group (p < 0.05).

CONCLUSION

Exercise may have a positive impact on bone mineral density.

ABBREVIATIONS

BMD: bone mineral density; SPSS: Statistical package for social science.How to cite this article: Hosseini S, Valizade R, Heydarabadi FD. Comparison of Bone Mineral Density among Alcoholism and Nonalcoholism Athlete and Nonathlete Subjects. Euroasian J Hepato-Gastroenterol 2014;4(1):1-3.

Female athlete triad and its components: toward improved screening and management

As female athletic participation has increased, the positive effects of exercise on health have become evident. However, with this growth in sports activity, a set of health problems unique to the female athlete has emerged. The female athlete triad as first described in 1992 by the American College of Sports Medicine consisted of disordered eating, amenorrhea, and osteoporosis; the definition was updated in 2007 to include a spectrum of dysfunction related to energy availability, menstrual function, and bone mineral density. For this review, a comprehensive search of databases-MEDLINE In-Process & Other Non-Indexed Citations, MEDLINE, EMBASE, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, and Scopus, from earliest inclusive dates to January 2013-was conducted by an experienced librarian with input from the authors. Controlled vocabulary supplemented with keywords such as female athlete triad, amenorrhea, oligomenorrhea, fracture, osteopenia, osteoporosis, bone disease, anorexia, bulimia, disordered eating, low energy availability was used to search for articles on female athlete triad. Articles addressing the prevalence, screening, and management of the female athlete triad were selected for inclusion in the review. This article reviews the current definitions of the triad components, epidemiology, pathophysiology, and recommended screening and management guidelines. The lack of efficacy of current screening of athletes is highlighted. Low energy availablity, from either dietary restriction or increased expenditure, plays a pivotal role in development of the triad. Athletes involved in "lean sports" (those that emphasize weight categories or aesthetics, such as ballet, gymnastics, or endurance running) are at highest risk. Treatment is centered on restoring energy availability to reverse adverse changes in the metabolic milieu. Prevention and early recognition of triad disorders are crucial to ensure timely intervention. Caregivers and physicians of female athletes must remain vigilant in education, recognition, and treatment of athletes at risk.

Bone mass in children and adolescents infected with human immunodeficiency virus

OBJECTIVE

To describe bone mineral density (BMD) and bone mineral content (BMC) in children and adolescents infected with the human immunodeficiency virus (HIV), and to compare them with data from the National Health and Nutrition Examination Survey IV (NHANES IV).

METHOD

The study included 48 children and adolescents (7 to 17 years old) infected with HIV through vertical transmission. BMC and BMD were measured by dual energy absorptiometry X-ray, by calculating z-scores based on data from NHANES IV. The information on clinical and laboratory parameters of infection by HIV was obtained from medical records. Physical activity, calcium intake, and skeletal maturation were also assessed. Descriptive and inferential statistical procedures were used, with levels of significance set at 5%.

RESULTS

Seropositive patients presented lower values compared to data from NHANES IV in all z-scores of bone mass (mean=-0.52 to -1.22, SD=0.91 and 0.84, respectively). Based on the subtotal z-BMD, there was a prevalence of 16.7% of children and adolescents with low bone mass for age. Individuals using protease inhibitors presented a lower total z-BMD when compared to the group that did not use (-1.31 vs. -0.79, p=0.02). There were no bone mass differences in relation to physical activity and calcium intake.

CONCLUSIONS

In the present sample children and adolescents living with HIV have low bone mass for age, and the use of protease inhibitors appears to be related to such decreases.

Bone ultrasound and physical activity in postmenopausal Spanish women

We studied the effects of moderate physical activity on bone mass in healthy postmenopausal women as assessed by quantitative bone ultrasound. We enrolled a total of 326 postmenopausal women (60.95 ± 8.51 years old and 13.02 ± 9.52 years since menopause) and categorized them by weekly physical activity in their leisure time (sedentary, moderate, and active). We administered a questionnaire on general health and diet and measured bone density by ultrasound on phalanges II-V in the nondominant hand. We found no significant difference in the amplitude-dependent speed of sound (Ad-SoS; p > .05) between sedentary and active women. We concluded that the changes induced by moderate physical activity on bone mass are minimal in healthy postmenopausal women.

Lean body mass, physical activity and quality of life in paediatric patients with inflammatory bowel disease and in healthy controls

BACKGROUND AND AIMS

Physical activity is important for muscle and bone strength in the growing child and may be impaired in paediatric patients with inflammatory bowel disease (IBD) even during quiescent disease. The SenseWearPro(2) armband allows to measure physical activity under everyday life conditions.

METHODS

Thirty-nine IBD patients (27 Crohn's disease, 12 ulcerative colitis, 24 boys) in remission (n=26) or with only mild disease activity (n=13) were compared to 39 healthy age and sex-matched controls. Body weight, height, body mass index (BMI), lean body mass as phase angle α (determined by bioelectrical impedance analysis), and dynamometric grip force were expressed as age- and sex-related Z-scores. SenseWearPro(2) armbands were applied for three consecutive days to record number of steps, duration of physical activity and sleeping time. Quality of life was assessed with the German KINDL and IMPACT III questionnaires, energy intake with prospective food protocols. Differences between patients and pair-matched controls were analysed by paired t-test.

RESULTS

Patients showed lower Z-scores for phase angle α (difference -0.72; 95% CI [-1.10; -0.34]) and lower grip strength (-1.02 [-1.58; -0.47]) than controls. They tended towards lesser number of steps per day (-1339 [-2760; 83]) and shorter duration of physical activity (-0.44 h [-0.94; 0.06]), particularly in females and patients with mild disease. Quality of life and energy intake did not differ between patients and controls.

CONCLUSION

In spite of quiescent disease lean body mass and physical activity were reduced. Interventions to encourage physical activity may be beneficial in this lifelong disease.

Effects of a plyometric training program for 3 children with neurofibromatosis type 1

BACKGROUND AND PURPOSE

To evaluate the feasibility and safety of plyometric training and to determine the effects on motor proficiency.

CASE DESCRIPTION

Three children with neurofibromatosis type 1, aged 5, 7, and 10 years, selected for representative ages, sexes, abilities, and outcomes participated in a 10-week plyometric training program. Outcome measures included throwing and jumping distance, performance on a self-selected goal, the Bruininks-Oseretsky Test of Motor Proficiency, Second Edition, and the Children's Assessment of Participation and Enjoyment.

OUTCOMES

All participants safely completed the program. Improvements were seen in distance and consistency of throwing and jumping, performance on the self-selected goal, and bilateral coordination composite scores. Increased diversity, but not intensity of physical activity, was observed.

DISCUSSION

A safe plyometric training program was implemented, resulting in gains in motor performance. It may be important to address personal and environmental barriers to physical activity participation to improve intensity of physical activity.

Fak depletion in both hematopoietic and nonhematopoietic niche cells leads to hematopoietic stem cell expansion

Hematopoietic stem cells (HSCs) reside in complex bone marrow microenvironments, where niche-induced signals regulate hematopoiesis. Focal adhesion kinase (Fak) is a nonreceptor protein tyrosine kinase that plays an essential role in many cell types, where its activation controls adhesion, motility, and survival. Fak expression is relatively increased in HSCs compared to progenitors and mature blood cells. Therefore, we explored its role in HSC homeostasis. We have used the Mx1-Cre-inducible conditional knockout mouse model to investigate the effects of Fak deletion in bone marrow compartments. The total number as well as the fraction of cycling Lin(-)Sca-1(+)c-kit(+) (LSK) cells is increased in Fak(-/-) mice compared to controls, while hematopoietic progenitors and mature blood cells are unaffected. Bone marrow cells from Fak(-/-) mice exhibit enhanced, long-term (i.e., 20-week duration) engraftment in competitive transplantation assays. Intrinsic Fak function was assessed in serial transplantation assays, which showed that HSCs (Lin(-)Sca-1(+)c-kit(+)CD34(-)Flk-2(-) cells) sorted from Fak(-/-) mice have similar self-renewal and engraftment ability on a per-cell basis as wild-type HSCs. When Fak deletion is induced after engraftment of Fak(fl/fl)Mx1-Cre(+) bone marrow cells into wild-type recipient mice, the number of LSKs is unchanged. In conclusion, Fak inactivation does not intrinsically regulate HSC behavior and is not essential for steady-state hematopoiesis. However, widespread Fak inactivation in the hematopoietic system induces an increased and activated HSC pool size, potentially as a result of altered reciprocal interactions between HSCs and their microenvironment.

Muscle strength and soccer practice as major determinants of bone mineral density in adolescents

OBJECTIVES

To analyse the relationship between isokinetic strength of the lower limb muscles and bone mineral density and content (BMD, BMC) of adolescent male soccer players and age-matched controls not involved in sport (12-15 years).

METHODS

A random sample of 151 young males was divided into soccer players (SG; n=117) and control subjects (CG; n=34). Peak torque of knee extensors (PTE) and flexors (PTF) was measured during isokinetic knee joint movement (90°/s) of the dominant and non-dominant lower limbs. BMD and BMC of the whole-body, lumbar spine, dominant/non-dominant lower limb were determined by dual-energy X-ray absorptiometry. Physical activity was monitored with accelerometers during 5 days. Estimated maturity offset was used as an indicator of biological maturity status.

RESULTS

Whole-body BMD (1.03±0.01 vs. 0.98±0.01 g/cm2, P=0.003) and dominant (1.09±0.01 vs. 1.02±0.01 g/cm2, P<0.001) and non-dominant (1.09±0.01 vs. 1.01±0.01 g/cm2, P<0.001) lower limb BMD was greater in SG compared to CG. No significant differences were found for BMC. Compared to CG, SG performed better in the YY-IE2 test (780±40 vs. 625±31 m), exhibited higher PTE (dominant limb: 155.2±30.3 vs. 123.4±37.0N m; non-dominant limb: 156.2±36.1 vs. 120.4±41.1 N m) and PTF muscles (dominant limb: 79.0±25.3 vs. 57.1±25.3 Nm; non-dominant limb: 73.3±20.7 vs. 57.0±24.2N m). Moreover, the PTE, soccer participation and maturity status were positively associated with the BMD at all body sites (r2=0.57-0.73, P<0.05).

CONCLUSIONS

Muscle strength of knee extensors is associated with BMD and BMC at all body sites. Muscle-skeletal structures respond positively to the weight-bearing and impact-loading imposed by soccer practice. Soccer seemed to be a multilateral balanced sport activity.

Concerted actions of insulin-like growth factor 1, testosterone, and estradiol on peripubertal bone growth: a 7-year longitudinal study

A better understanding of how bone growth is regulated during peripuberty is important for optimizing the attainment of peak bone mass and for the prevention of osteoporosis in later life. In this report we used hierarchical models to evaluate the associations of insulin-like growth factor 1 (IGF-1), estradiol (E(2) ), and testosterone (T) with peripubertal bone growth in a 7-year longitudinal study. Two-hundred and fifty-eight healthy girls were assessed at baseline (mean age 11.2 years) and at 1, 2, 3.5, and 7 years. Serum concentrations of IGF-1, E(2) , and T were determined. Musculoskeletal properties in the left lower leg were measured using peripheral quantitative computed tomography (pQCT). Serum levels of IGF-1, E(2) , and T increased dramatically before menarche, whereas they decreased, plateaued, or increased at a lower rate, respectively, after menarche. IGF-1 level was positively associated with periosteal circumference (PC) and total bone mineral content (tBMC) throughout peripuberty but not after adjustment for muscle cross-sectional area (mCSA). On the other hand, IGF-1 was associated with tibial length (TL) independently of mCSA before menarche. T was positively associated with TL, PC, tBMC, and cortical volumetric bone mineral density, independent of mCSA, before menarche but not after. E(2) was associated with TL positively before menarche but negatively after menarche. These findings suggest that during puberty, circulating IGF-1 promotes bone periosteal apposition and mass accrual indirectly, probably through stimulating muscle growth, whereas the effects of sex steroids on bone growth differ before and after menarche, presenting a biphasic pattern. Hence the concerted actions of these hormones are essential for optimal bone development in peripuberty.

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.

Adipose-derived stem cells in functional bone tissue engineering: lessons from bone mechanobiology

This review aims to highlight the current and significant work in the use of adipose-derived stem cells (ASC) in functional bone tissue engineering framed through the bone mechanobiology perspective. Over a century of work on the principles of bone mechanosensitivity is now being applied to our understanding of bone development. We are just beginning to harness that potential using stem cells in bone tissue engineering. ASC are the primary focus of this review due to their abundance and relative ease of accessibility for autologous procedures. This article outlines the current knowledge base in bone mechanobiology to investigate how the knowledge from this area has been applied to the various stem cell-based approaches to engineering bone tissue constructs. Specific emphasis is placed on the use of human ASC for this application.

Bone health and the female athlete triad in adolescent athletes

Peak bone mass (PBM) is a negative predictor of osteoporosis and lifelong fracture risk. Because osteoporosis is such a prevalent disease with life-threatening consequences, it is important to try to maximize PBM. Adolescence is a critical period for bone acquisition. This article discusses some of the differences in male and female skeletal development and modifiable factors that enhance bone accrual in this age group, particularly in athletes. Hormonal influences, effects of physical activity, and nutritional contributions are included, with a focus on the adolescent athlete. Emphasis is placed on the importance of appropriate energy availability in this age group. We also review prevention and treatment strategies for the female athlete triad (ie, the inter-relationship of decreased energy availability, menstrual irregularity, and low bone density) in adolescents and athletic women. Recommendations for maximizing bone density in both male and female adolescents are discussed.

Effects of different swimming exercise intensities on bone tissue composition in mice: a Raman spectroscopy study

OBJECTIVE

Raman spectroscopy was employed to evaluate the effect of different swimming intensities on femoral bone composition in an animal model.

BACKGROUND DATA

Intense swimming exercise may affect bone mineralization, and Raman technique has been shown to be effective in evaluating tissue composition (phosphate minerals and carbonate apatites - bands at 960 and 1170 cm(-1), as well as collagen matrix - amide I band at 1660 cm(-1)).

MATERIALS AND METHODS

Eighteen female Swiss Webster mice were separated into three groups (n = 6 per group) of sedentary (SED), and swimming with an intensity of 40% (PT-40) and 80% (PT-80) of the maximum load, with 6 weeks of training. Near-infrared Raman spectra (830 nm wavelength and 80 mW laser power) were obtained with a dispersive Raman spectrometer using a CCD camera and imaging spectrograph with 30-s integration time. Spectra were collected in the medial and lateral diaphysis of the femur and principal components analysis (PCA) was employed to extract features of the Raman bands of bone and to perform quantitative analysis.

RESULTS

PC1 vector resembles Raman spectra and carries information about apatite minerals and some contribution from organic matrix. A statistically significant difference was found in the PC1 scores (ANOVA, p < 0.05), indicating lower mineral concentrations in the femur in both the PT-40 and PT-80 groups compared to the SED group. These results corroborated with the radiographic assessment of bone density.

CONCLUSION

Raman technique associated with PCA statistics showed that intense swimming exercise may affect bone mineralization and remodeling in a mouse model of training.

Motor proficiency in children with neurofibromatosis type 1

PURPOSE

Neurofibromatosis type 1 (NF1) is a genetic disorder with associated musculoskeletal abnormalities, tumors, and developmental delays. The purpose of this study was to investigate and characterize the motor proficiency of children with NF1.

METHODS

Children with NF1 were assessed using the Bruininks-Oseretsky Test (BOT 2) instrument. The NF1 group scores were compared with age and sex-matched test norms.

RESULTS

Twenty-six children participated in the study. The NF1 group had statistically significant lower scores (P < .05) for the total motor composite (Z = -1.62) and 7 of the 8 subtests. Nineteen percent (n = 5) scored in the average category, 54% (n = 14) scored in the below-average category, and 27% (n = 7) scored in the well-below-average category.

CONCLUSIONS

Children with NF1 have significantly lower motor proficiency than the BOT 2 normative scores. The results indicate the BOT 2 is useful in identifying and characterizing delays in motor proficiency for children with NF1.

Lifestyle impact on lifetime bone loss in women and men: the Tromsø Study

A physically active, nonsmoking lifestyle with weight maintenance positively influences bone health. The authors estimated the effect of lifestyles on peak bone mass and lifetime bone loss in the Tromsø Study, Norway. Bone mineral density (BMD) was measured at distal and ultradistal forearm sites with single x-ray absorptiometric devices in 7,948 men and women aged 24-84 years in 1994-1995 and repeated in 2001 in 6,182 subjects. BMD was significantly higher at peak than at old age. However, the difference, estimated as lifetime loss, varied between lifestyle groups. Lifetime loss in nonsmoking, physically active men with a body mass index of 25 kg/m(2) compared with smoking, inactive, and lean men was 15.9% and 25.9% at the distal site and 17.5% and 29.7% at the ultradistal site, respectively. In women, the corresponding loss estimates were 34.4% and 45.7% and 35.6% and 55.7%, respectively. The differences in BMD at the age of 80 years correspond to an increased forearm fracture risk of 69% in men and 85% in women with greatest bone loss. A lifestyle including nonsmoking, a high physical activity level, and a high body weight reduces bone loss and fracture risk in both sexes, with increasing effect from peak bone mass to old age.

Exercise-induced amenorrhea and bone health in the adolescent athlete

Female participation in high school athletics has increased 800% in the last 30 years. The problem of exercise-induced amenorrhea was initially thought to be analogous to hypoestrogenism, but recent studies suggest that nutritional issues underlie most of the pathophysiology and that the mechanism is different from that seen in the primary hypogonadal state. Exercise-induced amenorrhea can be an indicator of an energy drain, and the presence of the other components of the female athlete triad-bone density loss and eating disorders-must be determined as well. Addressing skeletal problems related to nutritional and hormonal deficiencies in this population is of very high priority.

Bone density and young athletic women. An update

High-school girls and collegiate women have tremendous opportunities to participate in athletic teams. Young girls are also playing in club and select teams at an early age and often, year-round. There are many benefits for participating in sport and physical activity on both the physical and mental health of girls and women. Decreased risk for heart disease and diabetes mellitus, along with improved self-esteem and body-image, were among the first reported benefits of regular physical activity. In addition, sport participation and physical activity is also associated with bone health. Athletes have a greater bone mineral density compared with non-active and physically active females. The increase in bone mass should reduce the risk of fragility fractures in later life. There appears to be a window of opportunity during the development of peak bone mass in which the bone is especially responsive to weight-bearing physical activity. Impact loading sports such as gymnastics, rugby or volleyball tend to produce a better overall osteogenic response than sports without impact loading such as cycling, rowing and swimming. Relatively little is known about the impact of retiring from athletics on bone density. It appears that former athletes continue to have a higher bone density than non-athletes; however, the rate of bone loss appears to be similar in the femoral neck. The positive impact of sports participation on bone mass can be tempered by nutritional and hormonal status. It is not known whether female athletes need additional calcium compared with the general female population. Due to the increased energy expenditure of exercise and/or the pressure to obtain an optimal training bodyweight, some female athletes may develop low energy availability or an eating disorder and subsequently amenorrhoea and a loss of bone mineral density. The three inter-related clinical disorders are referred to as the 'female athlete triad'. This article presents a review of the relationship between sports training and bone health, specifically bone mineral density, in young athletic women.

Bone mineral density in female high school athletes: interactions of menstrual function and type of mechanical loading

During adolescence, skeletal integrity of girls is largely dependent on menstrual function and impact exercise, yet currently there is limited research regarding the interaction between menstrual status and type of mechanical loading associated with various high school sports. Our purpose was to examine associations of menstrual status, type of mechanical loading, and bone mineral density (BMD) in female high school athletes participating in high/odd impact or repetitive/non-impact sport. Participants were 161 female high school athletes (15.7+/-1.3 years; 165.3+/-6.9 cm; 59.4+/-8.7 kg) representing high/odd impact (n=93, including soccer, softball, volleyball, tennis, lacrosse, and track sprinters and jumpers), or repetitive/non-impact sports (n=68, including swimmers, cross-country and track distance runners who participated in events>or=800 m). Areal BMD was measured by DXA at the spine (L1-L4), proximal femur, and total body. Menstrual status was determined by self-report. Athletes with primary, secondary or oligomenorrhea were combined into a single group (oligo/amenorrheic) and compared to eumenorrheic athletes. Analysis of covariance (ANCOVA) with Bonferroni post hoc comparisons adjusted for age, BMI, and gynecological age were used to compare BMD of athletes in combined mechanical loading and menstrual status groups. We found significantly greater total hip (p=0.04) and trochanter (p=0.02) BMD (g cm(-2)) among eumenorrheic high/odd impact compared to eumenorrheic repetitive/non-impact athletes, and greater spine (p=0.01) and trochanter (p=0.04) BMD among high/odd impact eumenorrheic athletes compared to repetitive/non-impact oligo/amenorrheic athletes. Chi-squared analysis of BMD Z-scores adjusted for gynecological age showed a significantly greater percentage of repetitive/non-impact athletes (33.9%) compared to high/odd impact athletes (11.8%) with low spine BMD for their age (BMD Z-score<or=-1 SD) (p=0.001), indicating that a high percentage of female high school athletes participating in repetitive loading sports, and especially those with oligo/amenorrhea, may not be accruing bone at the expected rate. Female adolescent athletes should be evaluated periodically and advised of the possible negative effects of oligo/amenorrhea on bone health.