Bone density and amenorrhea in ballet dancers are related to a decreased resting metabolic rate and lower leptin levels

An appetite to win: Disordered eating behaviours amongst competitive cyclists

Competitive cyclists may be vulnerable to disordered eating (DE) and eating disorders (ED) due to perceived body composition optimisation and external influences within cycling culture and from stakeholders. Therefore, this study aimed to assess DE and ED risk in competitive cyclists using the Eating Attitudes Test (EAT-26), explore differences in responses based on sex, discipline and level of competition, and to gain insights into contributing factors towards DE via open-ended survey questions. In total, 203 participants completed a mixed-method questionnaire. Eating disorders were reported by 5.7% ( n = 11) of participants, with three being historic cases. The median (inter-quartile range) EAT-26 score was 8 (12) of a total possible score of 78. Disordered eating risk was observed in 16.7% of participants due to an EAT-26 score ≥20. Female participants had significantly higher scores than male participants (12.5 ± 17.5 vs. 6.5 ± 10.0; p = .004). There was no significant difference between road cyclists and off-road cyclists (7.0 ± 13.25 vs. 8.0 ± 10.5; p = .683). There was a significant difference in scores between novice/club/regional and national/elite/professional cyclists (6.0 ± 11.25 vs. 10.5 ± 12.0; p = .007). Thematic analysis of open-text responses found that the social environment of competitive cycling contributed towards DE behaviours and body image issues. These findings indicate competitive cyclists do appear to be an ‘at risk’ population for DE/ED. Therefore, there is need for stakeholders to enhance nutritional services, nutrition education and create supportive athlete environments.

Beyond Menstrual Dysfunction: Does Altered Endocrine Function Caused by Problematic Low Energy Availability Impair Health and Sports Performance in Female Athletes?

Low energy availability, particularly when problematic (i.e., prolonged and/or severe), has numerous negative consequences for health and sports performance as characterized in relative energy deficiency in sport. These consequences may be driven by disturbances in endocrine function, although scientific evidence clearly linking endocrine dysfunction to decreased sports performance and blunted or diminished training adaptations is limited. We describe how low energy availability-induced changes in sex hormones manifest as menstrual dysfunction and accompanying hormonal dysfunction in other endocrine axes that lead to adverse health outcomes, including negative bone health, impaired metabolic activity, undesired outcomes for body composition, altered immune response, problematic cardiovascular outcomes, iron deficiency, as well as impaired endurance performance and force production, all of which ultimately may influence athlete health and performance. Where identifiable menstrual dysfunction indicates hypothalamic-pituitary-ovarian axis dysfunction, concomitant disturbances in other hormonal axes and their impact on the athlete's health and sports performance must be recognized as well. Given that the margin between podium positions and "losing" in competitive sports can be very small, several important questions regarding low energy availability, endocrinology, and the mechanisms behind impaired training adaptations and sports performance have yet to be explored.

Patients with Adolescent Idiopathic Scoliosis Have Higher Metabolic Cost during High-Intensity Interval Training

BACKGROUND

Patients with adolescent idiopathic scoliosis (AIS) are found to have a lower level of physical activity, and may have reduced exercise capacity due to spinal deformity. Previous study showed the benefits of high-intensity interval training (HIIT), named E-Fit, which is specifically designed for patients with AIS to improve musculoskeletal health and psychological well-being. To optimize the beneficial effects of training, the current study aimed to investigate the appropriate exercise intensity and metabolic demand in patients with AIS when performing E-Fit.

METHODS

In all, 22 female subjects, 10 diagnosed with AIS and 12 gender-matched healthy controls, aged between 10 and 16 years, were recruited. Subjects were instructed to perform two trials of a seven min E-Fit. Breath-by-breath gas exchange parameters including oxygen consumption (VO₂), heart rate (HR) and the rate of perceived exertion (PRE) were measured during exercise. Demographic data and clinical features of AIS and body composition were obtained. Metabolic demand between AIS and control groups was compared using MANOVA with covariates adjustment.

RESULTS

Patients with AIS had an earlier onset of menarche (p = 0.01), higher visceral adipose tissue (p = 0.04) and percentage body fat (p = 0.03) as compared to controls. Patients with AIS showed a significantly higher adjusted means of VO₂ average in both the first (p = 0.014) and second trials (p = 0.011) of E-Fit. The adjusted mean of the highest measured VO₂ was higher than healthy controls and reached statistical significance in the second trial (p = 0.004). Both the AIS and control group exercised at a similar percentage of VO₂ peak (64.26% vs. 64.60%).

CONCLUSION

Patients with AIS showed higher oxygen consumption during E-Fit than heathy controls, which might indicate a higher metabolic cost. Patients with AIS could carry out exercise at a moderate exercise intensity similar to that of healthy controls, but special considerations in designing an exercise program, such as frequent rest intervals, would be useful to avoid fatigue among patients with AIS.

Management of Stress Fractures in Ballet

Stress fractures are highly prevalent in ballet dancers and lead to notable time loss from dancing. Nutritional status, body composition, bone mineral density, and rate of increase in activity are among the components that influence risk for stress fractures. Proper evaluation and management of stress fractures is essential including a review of the causative factors involved in each stress injury. The purpose of this article was to summarize current evidence for risk factors involved in dancers' stress fractures to optimize prevention and treatment. Identified associated factors include low energy availability, low bone mineral density, low fat body composition, abnormal lower extremity biomechanics, genetic factors, and high training loads.

Screening for Low Energy Availability in Male Athletes: Attempted Validation of LEAM-Q

A questionnaire-based screening tool for male athletes at risk of low energy availability (LEA) could facilitate both research and clinical practice. The present options rely on proxies for LEA such screening tools for disordered eating, exercise dependence, or those validated in female athlete populations. in which the female-specific sections are excluded. To overcome these limitations and support progress in understanding LEA in males, centres in Australia, Norway, Denmark, and Sweden collaborated to develop a screening tool (LEAM-Q) based on clinical investigations of elite and sub-elite male athletes from multiple countries and ethnicities, and a variety of endurance and weight-sensitive sports. A bank of questions was developed from previously validated questionnaires and expert opinion on various clinical markers of LEA in athletic or eating disorder populations, dizziness, thermoregulation, gastrointestinal symptoms, injury, illness, wellbeing, recovery, sleep and sex drive. The validation process covered reliability, content validity, a multivariate analysis of associations between variable responses and clinical markers, and Receiver Operating Characteristics (ROC) curve analysis of variables, with the inclusion threshold being set at 60% sensitivity. Comparison of the scores of the retained questionnaire variables between subjects classified as cases or controls based on clinical markers of LEA revealed an internal consistency and reliability of 0.71. Scores for sleep and thermoregulation were not associated with any clinical marker and were excluded from any further analysis. Of the remaining variables, dizziness, illness, fatigue, and sex drive had sufficient sensitivity to be retained in the questionnaire, but only low sex drive was able to distinguish between LEA cases and controls and was associated with perturbations in key clinical markers and questionnaire responses. In summary, in this large and international cohort, low sex drive was the most effective self-reported symptom in identifying male athletes requiring further clinical assessment for LEA.

Eating psychopathology in ballet dancers: a meta-analysis of observational studies

OBJECTIVE

To assess whether ballet dancers have higher eating psychopathology mean scores than the general population.

METHODS

Meta-analysis of cross-sectional observational studies comparing the scores of one or more of the validated eating psychopathological scales between ballet dancers and any control groups.

RESULTS

Twelve studies were included in the metanalysis. Ballet dancers had a significantly higher EAT score (12 studies retrieved, SMD 0.82 [95% CI 0.44-1.19], p < 0.00001, I² = 84)]; subgroup analysis suggested a possible role of control subjects' choice in explaining heterogeneity. Scores on the EDI subscales of Drive for Thinness, Bulimia, and Body dissatisfaction were available from four studies; Drive for Thinness was higher in ballet dancers (SMD 0.62 [0.01, 1.22]), as well as the Bulimia scale (SMD 0.38 [0.02, 0.73], p = 0.04) and the Body Dissatisfaction scale (SMD 0.34 [0.15, 0.53]). Data on Perfectionism, Interpersonal problems, Ineffectiveness, and Maturity fears, were available from three studies. Higher scores in Perfectionism (SMD 0.68 [0.24, 1.12] p = 0.02), Interpersonal problems (SMD 0.24 [0.02, 0.47], in Inefficacy, (SMD 2.18 [1.31, 3.06]) were found for ballet dancers; on the other hand, Maturity fears scores were not significantly different between ballet dancers and controls (IV-MD = 0.15 [- 0.07, 0.36]). Seven studies reported tests not performed elsewhere.

DISCUSSION

Ballet dancers show a higher level of restriction and drive for thinness than controls, and they may be, therefore, at higher risk for the development of eating disorders. Available studies do not allow the discrimination of dysfunctional eating attitudes and behaviors from adaptive responses.

LEVEL OF EVIDENCE

Level I (evidence obtained from systematic reviews and meta-analyses).

Endospanin Is a Candidate for Regulating Leptin Sensitivity

The hypothesis advanced is that endospanin, a highly conserved vesicle traffic protein in vertebrates, regulates leptin sensitivity in bone signaling. The effects of leptin on bones are well-studied but without consensus on whether the increases in leptin signaling stimulate bone gain or loss. The bone response may depend on leptin sensitivity, and endospanin is an established modulator of leptin sensitivity. An argument is advanced to develop zebrafish models for specific leptin signaling pathways. Zebrafish have well-developed molecular tools (e.g., CRISPR) and the advantage of non-destructive sampling of bones in the form of scales. Using these tools, experiments are described to substantiate the role of endospanin in zebrafish bone dynamics.

Agreement between B-Mode Ultrasound and Air Displacement Plethysmography in Preprofessional Ballet Dancers

PURPOSE

This study aimed to assess the agreement between B-mode ultrasound and air displacement plethysmography (ADP) body composition results in preprofessional ballet dancers.

METHODS

Male (n = 21, Mage = 17.2 ± 1.7 yr, MBMI = 20.5 ± 2.0 kg·m-2) and female (n = 27, Mage = 16.1 ± 1.4 yr, MBMI = 18.3 ± 1.3 kg·m-2) dancers were assessed by ADP and ultrasound to determine body fat percentage (%BF), fat mass (FM), and fat-free mass (FFM). Pearson's correlations were used to assess agreement, and paired t-tests were used to determine differences between devices (α = 0.05). Ultrasound validity was assessed using SEE and total error. Bland-Altman plots were used to identify 95% limits of agreement.

RESULTS

Agreement was high for %BF (females, r = 0.94; males, r = 0.77), FM (females, r = 0.94; males, r = 0.73), and FFM (females, r = 0.95; males, r = 0.99). However, ultrasound overestimated %BF and FM and underestimated FFM (P < 0.05) compared with ADP in females only. In addition, there were stronger agreement and lower error for FFM compared with both %BF and FM regardless of sex.

CONCLUSION

There is strong agreement between ultrasound and ADP in this population. Although ultrasound may be a useful field tool to assess body composition, future research is needed to refine %BF equations in this population to reduce calculation errors.

Physiological Parameters of Bone Health in Elite Ballet Dancers

Stress fractures are common among elite ballet dancers whereby musculoskeletal health may be affected by energy balance and overtraining.

PURPOSE

This study aimed to characterize bone health in relation to stress fracture history, body composition, eating disorder risk, and blood biomarkers in professional male and female ballet dancers.

METHODS

A single cohort of 112 dancers (male: 55, 25 ± 6 yr; female: 57, 24 ± 6 yr) was recruited. All participants underwent bone and body composition measures using dual-energy x-ray absorptiometry. In a subset of our cohort (male: 30, 24 ± 6 yr; female, 29, 23 ± 5 yr), a blood panel, disordered eating screen, menstrual history, and stress fracture history were also collected. Age-matched Z scores and young-adult T scores were calculated for bone mineral density (BMD) and body composition. Independent-samples t-tests and Fisher's exact tests were used to compare BMD, Z-scores, T scores, and those with and without history of stress fractures. A 1 × 3 ANOVA was used to compare BMD for those scoring 0-1, 2-6, and 7+ using the EAT26 questionnaire for eating disorder risk. Regression was used to predict BMD from demographic and body composition measures.

RESULTS

Female dancers demonstrated reduced spinal (42nd percentile, 10%T < -1) and pelvic (16th percentile, 76%T < -1) BMD. Several anthropometric measures were predictive of BMD (P < 0.05, r = 0.65-0.81, standard error of estimate = 0.08-0.10 g·cm, percent error = 6.3-8.5). Those scoring >1 on EAT26 had lower BMD than did those with a score of 0-1 (P < 0.05).

CONCLUSIONS

Professional female ballet dancers exhibit reduced BMD, fat mass, and lean mass compared with the general population whereby low BMD and stress fractures tend to be more prevalent in those with a higher risk of disordered eating. Anthropometric and demographic measures are predictive of BMD in this population.

Female Athlete Body Project Intervention with Professional Dancers: A Pilot Trial

As aesthetic athletes, professional dancers have increased vulnerability for eating disorders (EDs), with three times higher risk than non-dancers. Among ballet dancers, generalized risk for EDs associated with internalization of western cultural female beauty ideals is compounded by idealization of a ballet-specific body ideal, a combination that confers unique vulnerability for eating pathology. Empirical support has been established for an athlete-specific intervention promoting body acceptance and reduced eating pathology among general populations of young-adult women and female collegiate athletes; the current study adapted this intervention for pilot implementation among professional ballet dancers. Participants from two elite ballet companies (N = 19) were randomized to a control and intervention condition. All participants self-reported eating pathology and related variables pre- and post-intervention, and at six-week follow-up. Post-intervention, participants receiving the intervention demonstrated reductions in body dissatisfaction, p = .005, r = -.63, dietary restraint, p = .008, r = -.59, and eating pathology, p = .007, r = -.60, as compared to control group counterparts; significant differences were retained at follow-up. Results provide preliminary evidence that this intervention has the potential to provide a feasible and acceptable means of ED prevention in female professional ballet dancers. Barriers to feasibility are identified and discussed.

Eating behaviours related to psychological stress are associated with functional hypothalamic amenorrhoea in exercising women

Functional hypothalamic amenorrhoea (FHA) can occur due to the independent or combined effects of psychogenic and energetic stressors. In exercising women, research has primarily focused on energy deficiency as the cause of FHA while psychological stressors have been ignored. To assess both psychological and metabolic factors associated with FHA in exercising women, we performed across-sectional comparison of 61 exercising women (≥2 hours/week, age 18-35 years, BMI 16-25kg/m²), who were eumenorrheic or amenorrhoeic confirmed by daily urine samples assayed for reproductive hormone metabolites. Psychological factors and eating behaviours were assessed by self-report questionnaires. Exercising women with FHA had lower resting metabolic rate (p=0.023), T3 (p<0.001), T4 (p=0.013), leptin (p=0.002), higher peptide YY (p<0.001), greater drive for thinness (p=0.017), greater dietary cognitive restraint (p<0.001), and displayed dysfunctional attitudes, i.e., need for social approval (p=0.047) compared to eumenorrheic women. Amenorrhoeic women displayed asignificant positive correlation between the need for social approval and drive for thinness with indicators of stress, depression, and mood, which was not apparent in eumenorrheic women. In exercising women with FHA, eating behaviours are positively related to indicators of psychological stress and depression.

Menstrual disorders in amateur dancers

Background

Rigorous exercise undertaken by young girls, combined with a negative energetic balance, is related to substantial physiological changes in a competitor’s body, often leading to hormonal imbalance manifested by: delayed puberty, delayed menstruation, menstrual disorders, and even long-term secondary amenorrhoea. Very lean competitors, with insufficient body fat content, are not capable of maintaining oestrogen production at an optimal level, which results in hypothalamic-pituitary-gonadal axis abnormalities and menstrual disorders. Studies involving research on menstrual disorders in amateur dancers are scarce. Therefore, the aim of the study was to investigate whether menstrual disorders are present among young amateur dancers.

Methods

The study involved 233 females of a mean age of 22.1 years (SD ± 4.9), training amateur ballroom dancing. The questionnaire included questions regarding the regularity of the menstrual cycle, including the absence of a menstrual period, causes of menstrual disorders and breakthrough bleeding.

Results

Menstrual disorders following a period of regular menstruation were reported by 132 (56.7%) of ballroom dancers. In 105 (79.5%), the absence of a menstrual period lasted for less than 3 months, in 18 (13.6%) it persisted for 3 up to 6 months, while in 9 (6.8%) it lasted for over 6 months.

Conclusions

The research conducted concluded that with an increased number of hours spent in training by amateur dancers, there was a statistically significant increase in the chance for menstrual disorders; the more training sessions per week there were, the longer the breaks in menstruation were noted.

Electronic supplementary material

The online version of this article (10.1186/s12905-019-0779-1) contains supplementary material, which is available to authorized users.

Assessment of Dietary Intake, Energy Status, and Factors Associated With RED-S in Vocational Female Ballet Students

Elite ballet dancers are at risk of health issues associated with Relative Energy Deficiency in Sport (RED-S). This study determined the nutritional status, estimated energy status, and assessed factors related to RED-S in vocational female ballet students. Using a cross-sectional study design, we measured dietary intake (food diaries and 24 h dietary-recall) and energy expenditure (accelerometry) in vocational female ballet students (n = 20; age: 18.1 ± 1.1 years; body mass index: 19.0 ± 1.6 kg·m²; body fat: 22.8 ± 3.4%) over 7 days, including 5 weekdays (with dance training) and 2 weekend days (without scheduled dance training). Furthermore, we assessed eating behaviors, menstrual function, risk of RED-S (questionnaires), and body composition (dual x-ray absorptiometry). Energy and macronutrient intakes of vocational ballet students were similar during weekdays and weekend days (P > 0.050), whereas total energy expenditure was greater on weekdays than weekend days (P < 0.010; 95% CI: 212, 379). Energy balance was lower on weekdays (-425 ± 465 kcal·day^-1) than weekend days (-6 ± 506 kcal·day^-1, P = 0.015; 95% CI: -748, -92). Exercise energy expenditure was greater on weekdays (393 ± 103 kcal·day^-1) than weekend days (213 ± 129 kcal·day^-1; P < 0.010; 95% CI: 114, 246), but energy availability was similar between time periods (weekdays 38 ± 13 kcal·kg FFM·day^-1; weekend days 44 ± 13 kcal·kg FFM·day^-1; P = 0.110). Overall, 35% of participants had an energy intake <1,800 kcal·day^-1, 44% had reduced energy availability (30-45 kcal·kg FFM·day^-1), and 22% had low energy availability (<30 kcal·kg FFM·day^-1). Menstrual dysfunctions were reported in 40% of participants; 15 and 25% reported oligomenorrhea and secondary amenorrhea, respectively; while 65% were classified at risk of RED-S (based on the Low Energy Availability in Females Questionnaire). All participants had adequate bone health (bone mineral density Z-score: 1.1 ± 0.9 SD), but 20% had <85% expected body weight. The observation of an energy deficit in vocational female ballet students was primarily attributed to an inability to plan energy intake and thereby meet higher energy requirements during ballet training weekdays. Screening for factors associated with RED-S and tailoring education programs to inform energy and nutrition requirements for health and training are recommended in elite young ballet students.

Low RMRratio as a Surrogate Marker for Energy Deficiency, the Choice of Predictive Equation Vital for Correctly Identifying Male and Female Ballet Dancers at Risk

Ballet dancers are reported to have an increased risk for energy deficiency with or without disordered eating behavior. A low ratio between measured (m) and predicted (p) resting metabolic rate (RMRratio < 0.90) is a recognized surrogate marker for energy deficiency. We aimed to evaluate the prevalence of suppressed RMR using different methods to calculate pRMR and to explore associations with additional markers of energy deficiency. Female (n = 20) and male (n = 20) professional ballet dancers, 19–35 years of age, were enrolled. mRMR was assessed by respiratory calorimetry (ventilated open hood). pRMR was determined using the Cunningham and Harris–Benedict equations, and different tissue compartments derived from whole-body dual-energy X-ray absorptiometry assessment. The protocol further included assessment of body composition and bone mineral density, blood pressure, disordered eating (Eating Disorder Inventory-3), and for females, the Low Energy Availability in Females Questionnaire. The prevalence of suppressed RMR was generally high but also clearly dependent on the method used to calculate pRMR, ranging from 25% to 80% in males and 35% to 100% in females. Five percent had low bone mineral density, whereas 10% had disordered eating and 25% had hypotension. Forty percent of females had elevated Low Energy Availability in Females Questionnaire score and 50% were underweight. Suppressed RMR was associated with elevated Low Energy Availability in Females Questionnaire score in females and with higher training volume in males. In conclusion, professional ballet dancers are at risk for energy deficiency. The number of identified dancers at risk varies greatly depending on the method used to predict RMR when using RMRratio as a marker for energy deficiency.

Influence of foot position and vision on dynamic postural strategies during the "grand plié" ballet movement (squatting) in young and adult ballet dancers

PURPOSE

To analyse dynamic postural strategies during the "grand plié" in two different foot positions (parallel or turned out), with and without vision, and as a function of age in ballet dancers.

METHOD

Twenty young dancers (YD) aged from 8 to 16 years, and 20 adult dancers (AD) aged from 17 to 30 years were recruited. Center of pressure (CoP) and ground reaction forces (GRF) were recorded (500 Hz) during the grand plié (lowering, squatting and rising). This movement was tested with the feet parallel and with both lower limbs turned out (foot angle >140°), with eyes open (EO) and eyes closed (EC). Groups were compared using Student t-tests. Repeated analysis of variance was used to examine the effects of eyes and foot conditions, with a significance level of p < 0.05.

RESULTS

The results of this study showed that dynamic postural strategies during the "grand plié" ballet movement are influenced by age, foot position and visual condition. CoP displacement length (p < 0.003) and CoP speed (p < 0.003) were higher in YD compared with AD. CoP surface (p < 0.05), mediolateral CoP speed (p < 0.048) and GRF parameters, particularly the mediolateral (p < 0.049), were higher than in the parallel than the turned out position. In both groups all CoP (p < 0.042) and GRF parameters (p < 0.049), except the vertical component, were higher with EC than EO.

CONCLUSION

The effect of foot position was greatest with EO. The parallel position was less stable. The YD were more unstable in the parallel position, particularly with EC. For both groups, the lack of vision increased instability. These results show the importance of integrating balance training in a variety of foot positions and visual conditions, particularly during the initial stages of training to prevent injury.

Leptin Regulation of Gonadotrope Gonadotropin-Releasing Hormone Receptors As a Metabolic Checkpoint and Gateway to Reproductive Competence

The adipokine leptin signals the body's nutritional status to the brain, and particularly, the hypothalamus. However, leptin receptors (LEPRs) can be found all throughout the body and brain, including the pituitary. It is known that leptin is permissive for reproduction, and mice that cannot produce leptin (Lep/Lep) are infertile. Many studies have pinpointed leptin's regulation of reproduction to the hypothalamus. However, LEPRs exist at all levels of the hypothalamic-pituitary-gonadal axis. We have previously shown that deleting the signaling portion of the LEPR specifically in gonadotropes impairs fertility in female mice. Our recent studies have targeted this regulation to the control of gonadotropin releasing hormone receptor (GnRHR) expression. The hypotheses presented here are twofold: (1) cyclic regulation of pituitary GnRHR levels sets up a target metabolic checkpoint for control of the reproductive axis and (2) multiple checkpoints are required for the metabolic signaling that regulates the reproductive axis. Here, we emphasize and explore the relationship between the hypothalamus and the pituitary with regard to the regulation of GnRHR. The original data we present strengthen these hypotheses and build on our previous studies. We show that we can cause infertility in 70% of female mice by deleting all isoforms of LEPR specifically in gonadotropes. Our findings implicate activin subunit (InhBa) mRNA as a potential leptin target in gonadotropes. We further show gonadotrope-specific upregulation of GnRHR protein (but not mRNA levels) following leptin stimulation. In order to try and understand this post-transcriptional regulation, we tested candidate miRNAs (identified with in silico analysis) that may be binding the Gnrhr mRNA. We show significant upregulation of one of these miRNAs in our gonadotrope-Lepr-null females. The evidence provided here, combined with our previous work, lay the foundation for metabolically regulated post-transcriptional control of the gonadotrope. We discuss possible mechanisms, including miRNA regulation and the involvement of the RNA binding protein, Musashi. We also demonstrate how this regulation may be vital for the dynamic remodeling of gonadotropes in the cycling female. Finally, we propose that the leptin receptivity of both the hypothalamus and the pituitary are vital for the body's ability to delay or slow reproduction during periods of low nutrition.

Reduced energy availability: implications for bone health in physically active populations

Purpose

The present review critically evaluates existing literature on the effects of short- and long-term low energy availability (EA) on bone metabolism and health in physically active individuals.

Methods

We reviewed the literature on the short-term effects of low EA on markers of bone metabolism and the long-term effects of low EA on outcomes relating to bone health (bone mass, microarchitecture and strength, bone metabolic markers and stress fracture injury risk) in physically active individuals.

Results

Available evidence indicates that short-term low EA may increase markers of bone resorption and decrease markers of bone formation in physically active women. Bone metabolic marker responses to low EA are less well known in physically active men. Cross-sectional studies investigating the effects of long-term low EA suggest that physically active individuals who have low EA present with lower bone mass, altered bone metabolism (favouring bone resorption), reduced bone strength and increased risk for stress fracture injuries.

Conclusions

Reduced EA has a negative influence on bone in both the short- and long-term, and every effort should be made to reduce its occurrence in physically active individuals. Future interventions are needed to explore the effects of long-term reduced EA on bone health outcomes, while short-term low EA studies are also required to give insight into the pathophysiology of bone alterations.

Energy expenditure and nutrition status of ballet, jazz and contemporary dance students

Purpose: To evaluate of the energy expenditure in 3 types of dance classes (ballet, Jazz, and contemporary), as well as of the daily energy balance depending on dance type. Materials and methods: 40 females attending dance classes with a median age of 21.0 (19.0-25.0) and 10 males with a median age of 27.0 (20.0-28.0) participated in this study. The energy cost of each dance class was measured using the BodyMedia SenseWear Sensor and total daily energy expenditure was evaluated using a 3-day recording of physical activity. The dietary intake was evaluated with a 3-day food diary recording. Statistical analysis was performed using the SPSS software. Results: Median energy expenditure varied from 306 (277-328) Kcals/class for contemporary dance to 327 (290-355) Kcals/class for ballet and 369 (333-394) Kcals/class for jazz for females with significant differences between contemporary and jazz classes. For males, energy expenditure was 508 (447-589) Kcals/class and 564 (538-593) Kcals/class for ballet and jazz classes, respectively. Females had lower values for all anthropometric measurements, energy intake, macronutrient intakes, and energy expenditure, compared with males. The anthropometric characteristics did not differ between dance types. Both female and male dance students were in a negative energy balance. Conclusions: The use of sensors such as BodyMedia SenseWear together with keeping daily diaries make measurement of physical activity in dancing reliable and accurate. Exercise expenditure differs across types of dance in females but not in males. Both sexes had inadequate energy and carbohydrate intakes.

Energy intake and energy expenditure of pre-professional female contemporary dancers

Many athletes in aesthetic and weight dependent sports are at risk of energy imbalance. However little is known about the exercise and eating behaviours of highly trained dance populations. This investigation sought to determine the energy intake and energy expenditure of pre-professional female contemporary dancers. Twenty-five female contemporary dance students completed the study. Over a 7-day period, including five week days (with scheduled dance training at a conservatoire) and two weekend days (with no scheduled dance training at the conservatoire), energy intake (self-reported weighed food diary and 24 h dietary recall) and expenditure (tri-axial accelerometry) were recorded. Mean daily energy intake and expenditure were different over the 7-day period (P = 0.014) equating to an energy deficit of -356 ± 668 kcal·day-1 (or -1.5 ± 2.8 MJ·day-1). Energy expenditure was not different when comparing week and weekend days (P = 0.297). However daily energy intake (P = 0.002), energy availability (P = 0.003), and energy balance (P = 0.004) were lower during the week compared to the weekend, where energy balance became positive. The percentage contribution of macronutrients to total energy intake also differed; with higher fat (P = 0.022) and alcohol (P = 0.020), and lower carbohydrate (P = 0.001) and a trend for lower protein (P = 0.051) at the weekend. Energy balance and appropriate macronutrient intake are essential for maintaining the demands of training, performance and recovery. Whilst aesthetics are important, female contemporary dancers may be at risk of the numerous health and performance impairments associated with negative energy balance, particularly during periods of scheduled training.

Associations between body composition and lifestyle factors with bone mineral density according to time since menopause in women from Southern Brazil: a cross-sectional study

BACKGROUND

The aim of this study was to investigate whether body composition, dietary pattern and habitual physical activity are associated with BMD according to time since menopause in women from Southern Brazil with no clinical evidence of disease.

METHODS

99 participants were enrolled and anthropometry, body composition and BMD by dual energy x-ray absorptiometry, rest metabolic rate by indirect calorimetry, dietary pattern by semi quantitative food frequency questionnaire and habitual physical activity by pedometer were performed.

RESULTS

Mean age was 55.2 ± 4.9 years and mean time since menopause was 6.8 ± 1.0 years. Weight, BMI, lean and fat mass and RMR were higher in women with less than 5 years since menopause with normal versus low bone mass. No differences were found in the studied variables between participants with normal or low bone mass and more than 5 years of menopause. Women with > 5 years since menopause had higher prevalence of osteoporosis, as well as lower BMD in all sites when compared to those with less time since menopause. Calories, carbohydrate, protein, fat and micronutrients intake were similar between groups. When the sample was adjusted for time since menopause, the odds ratio (OR) for low bone mass was 5.21 (95% CI 1.57-17.25, P = 0.004) for BMI <25 kg/m(2), for lean mass <37.5 Kg an OR of 4.4 (95% CI 1.64-11.80, P = 0.004, for fat mass <26.0 Kg an OR of 3.39 (95% CI 1.29-8.85, P = 0.010) and for the intake of vitamin A < 700 mcg/day an OR of 3.00 (95% CI 1.13-7.94, P = 0.012). Low meat and eggs intake or low protein intake did not influence the odds ratio for low bone mass.

CONCLUSION

In this cross-sectional study with postmenopausal women with no clinical evidence of disease, time since menopause, low lean and fat mass were associated with low bone mass. Calories and macronutrients intake as well as habitual physical activity did not interfere with BMD, but participants were mostly sedentary. Further studies are needed in order to determine whether the adequate intake of specific food groups and the type of physical activity could attenuate the time since menopause impact on BMD.

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.

Nine-month nutritional intervention improves restoration of menses in young female athletes and ballet dancers

Background

We hypothesized that an intervention designed to increase the energy and nutrient intake could serve as an efficacious method to restore normal menstrual functions in athletes and ballet dancers.

Methods

In this study, a 9-month nutritional intervention (NI) was conducted in 21 dancers and 31 athletes with menstrual disorders. Analyses of the body composition were performed, and the levels of LH, FSH, P, E2, TSH, T, PRL, SHBG, leptin, resting metabolic rate (RMR), energy and nutrient intake, total energy expenditure were estimated. The NI was based on an individual diet. The effects of the NI were controlled after 3, 6 and 9 months of use.

Results

The NI resulted in a significant change of the energy and nutrient intake. After 9 months, a significant increase in the LH level among dancers was observed, while in female athletes this effect was seen after 3 months of the NI use. The 9-month NI resulted in the restoration of regular menses in 3 dancers and 7 athletes, respectively. Women with regular cycles had a higher percentage of the fat mass (FM).

Conclusions

A non-pharmacological intervention in female athletes and ballet dancers with menstrual disorders can restore regular menstrual cycles, although restoration of menses may take more than 1 year. An increase in the body fat mass may be one of the most important predictors of restoration of menses.

Selective deletion of leptin receptors in gonadotropes reveals activin and GnRH-binding sites as leptin targets in support of fertility

The adipokine, leptin (LEP), is a hormonal gateway, signaling energy stores to appetite-regulatory neurons, permitting reproduction when stores are sufficient. Dual-labeling for LEP receptors (LEPRs) and gonadotropins or GH revealed a 2-fold increase in LEPR during proestrus, some of which was seen in LH gonadotropes. We therefore investigated LEPR functions in gonadotropes with Cre-LoxP technology, deleting the signaling domain of the LEPR (Lepr-exon 17) with Cre-recombinase driven by the rat LH-β promoter (Lhβ-cre). Selectivity of the deletion was validated by organ genotyping and lack of LEPR and responses to LEP by mutant gonadotropes. The mutation had no impact on growth, body weight, the timing of puberty, or pregnancy. Mutant females took 36% longer to produce their first litter and had 50% fewer pups/litter. When the broad impact of the loss of gonadotrope LEPR on all pituitary hormones was studied, mutant diestrous females had reduced serum levels of LH (40%), FSH (70%), and GH (54%) and mRNA levels of Fshβ (59%) and inhibin/activin β A and β B (25%). Mutant males had reduced serum levels of GH (74%), TSH (31%), and prolactin (69%) and mRNA levels of Gh (31%), Ghrhr (30%), Fshβ (22%), and glycoprotein α-subunit (Cga) (22%). Serum levels of LEP and ACTH and mRNA levels of Gnrhr were unchanged. However, binding to GnRH receptors was reduced in LEPR-null LH or FSH gonadotropes by 82% or 89%, respectively, in females (P < .0001) and 27% or 53%, respectively, in males (P < .03). This correlated with reductions in GnRH receptor protein immunolabeling, suggesting that LEP's actions may be posttranscriptional. Collectively, these studies highlight the importance of LEP to gonadotropes with GnRH-binding sites and activin as potential targets. LEP may modulate population growth, adjusting the number of offspring to the availability of food supplies.

Prevalence of eating disorders amongst dancers: a systemic review and meta-analysis

Eating disorders in dancers are thought to be common, but the exact rates remain to be clarified. The aim of this study is to systematically compile and analyse the rates of eating disorders in dancers. A literature search, appraisal and meta-analysis were conducted. Thirty-three relevant studies were published between 1966 and 2013 with sufficient data for extraction. Primary data were extracted as raw numbers or confidence intervals. Risk ratios and 95% confidence intervals were calculated for controlled studies. The overall prevalence of eating disorders was 12.0% (16.4% for ballet dancers), 2.0% (4% for ballet dancers) for anorexia, 4.4% (2% for ballet dancers) for bulimia and 9.5% (14.9% for ballet dancers) for eating disorders not otherwise specified (EDNOS). The dancer group had higher mean scores on the EAT-26 and the Eating Disorder Inventory subscales. Dancers, in general, had a higher risk of suffering from eating disorders in general, anorexia nervosa and EDNOS, but no higher risk of suffering from bulimia nervosa. The study concluded that as dancers had a three times higher risk of suffering from eating disorders, particularly anorexia nervosa and EDNOS, specifically designed services for this population should be considered.

Adiponectin is a candidate biomarker of lower extremity bone density in men with chronic spinal cord injury

Adipose tissue is a major regulator of bone metabolism and in the general population obesity is associated with greater bone mineral density (BMD). However, bone-fat interactions are multifactorial, and may involve pathways that influence both bone formation and resorption with competing effects on the skeleton. One such pathway involves adipocyte production of adipokines that regulate bone metabolism. In this study we determined the association between BMD, walking status, and circulating adipokines (adiponectin and leptin) in 149 men with chronic spinal cord injury (SCI). Although adipokine levels did not vary significantly based on walking status, there was a significant inverse association between adiponectin and BMD in wheelchair users independent of body composition. We found no association between adiponectin and BMD in the walkers and no association between leptin and BMD in either group. These findings suggest that for subjects with chronic SCI, walking may mitigate the effect of adiponectin mediated bone loss. For wheelchair users, adipose-derived adiponectin may contribute to SCI-induced osteoporosis because the osteoprotective benefits of obesity appear to require mechanical loading during ambulation.

Cortisol secretory parameters in young exercisers in relation to LH secretion and bone parameters

OBJECTIVE

Amenorrhoea and low bone density are common in excessive exercisers, yet endocrine factors that differentiate adolescent amenorrhoeic exercisers (AE) from eumenorrhoeic exercisers (EE) are unclear. We have previously reported that high ghrelin and low leptin predict lower LH secretion in AE. Leptin and ghrelin impact cortisol secretion, and hypercortisolaemia can inhibit LH pulsatility. We hypothesized that higher cortisol secretion in young endurance weight-bearing AE compared with EE and nonexercisers predicts lower LH secretion, lower levels of a bone formation marker and higher levels of a bone resorption marker.

DESIGN

Cross-sectional.

SUBJECTS

We studied 21 AE, 18 EE and 20 nonexercisers aged 14-21 years (BMI 10th-90th%iles).

MEASUREMENTS

Subjects underwent frequent sampling (11 p.m. to 7 a.m.) to assess cortisol, ghrelin, leptin and LH secretory dynamics. Fasting levels of a bone formation (P1NP) and bone resorption (CTX) marker were measured.

RESULTS

BMI did not differ among groups. Cortisol pulse amplitude, mass, half-life and area under the curve (AUC) were highest in AE (P = 0.04, 0.007, 0.04 and 0.003) and were associated inversely with fat mass (r = -0.29, -0.28 and -0.35, P = 0.03, 0.04 and 0.007). We observed inverse associations between cortisol and LH AUC (r = -0.36, P = 0.008), which persisted after controlling for fat mass, leptin and ghrelin AUC. Cortisol correlated positively with CTX in EE and inversely with P1NP in nonexercisers.

CONCLUSIONS

Higher cortisol secretion in AE compared with EE and nonexercisers is associated with lower LH secretion. Effects of leptin and ghrelin on LH secretion may be mediated by increased cortisol.

Plasma adipocytokine and ghrelin levels in relation to bone mineral density in prepubertal rhythmic gymnasts

The aim of the present study was to investigate possible differences in plasma adipocytokine and ghrelin levels and body composition parameters in prepubertal rhythmic gymnasts (RG) and untrained controls (UC), and to examine the relationships of bone mineral density (BMD) with hormonal status in prepubertal children with different physical activity patterns. Eighty-nine 7- to 9-year-old girls participated in the study (RG, n = 46; UC, n = 43). Body composition and BMD were measured by dual-energy X-ray absorptiometry. Bone maturity was estimated by using a radiograph of the nondominant hand. The measured whole-body, lumbar spine (LS), and femoral neck (FN) BMD values were significantly higher (P < 0.05) in gymnasts than in controls. In addition, RG presented significantly lower and higher values (P < 0.05) for leptin and ghrelin concentrations, respectively, in comparison with UC. No differences were observed for adiponectin levels between the studied groups. No relationships between measured BMD values with leptin and ghrelin were observed even after adjustment for age and fat mass (FM) in RG. Whole-body and LS BMD values were significantly correlated with leptin after controlling for age and FM (r = 0.32, P < 0.05) in UC. Femoral neck BMD remained significantly correlated with ghrelin after adjusting for age and FM (r = -0.4, P < 0.05) in UC. No relationships were found between measured BMD values and adiponectin even after controlling for age and FM values in both groups. In conclusion, although all measured BMD values were significantly higher in RG, plasma adipocytokine and ghrelin concentrations were not directly related to bone mineralization in prepubertal RG in contrast to UC.

Obstacles in the optimization of bone health outcomes in the female athlete triad

Maintaining low body weight for the sake of performance and aesthetic purposes is a common feature among young girls and women who exercise on a regular basis, including elite, college and high-school athletes, members of fitness centres, and recreational exercisers. High energy expenditure without adequate compensation in energy intake leads to an energy deficiency, which may ultimately affect reproductive function and bone health. The combination of low energy availability, menstrual disturbances and low bone mineral density is referred to as the 'female athlete triad'. Not all athletes seek medical assistance in response to the absence of menstruation for 3 or more months as some believe that long-term amenorrhoea is not harmful. Indeed, many women may not seek medical attention until they sustain a stress fracture. This review investigates current issues, controversies and strategies in the clinical management of bone health concerns related to the female athlete triad. Current recommendations focus on either increasing energy intake or decreasing energy expenditure, as this approach remains the most efficient strategy to prevent further bone health complications. However, convincing the athlete to increase energy availability can be extremely challenging. Oral contraceptive therapy seems to be a common strategy chosen by many physicians to address bone health issues in young women with amenorrhoea, although there is little evidence that this strategy improves bone mineral density in this population. Assessment of bone health itself is difficult due to the limitations of dual-energy X-ray absorptiometry (DXA) to estimate bone strength. Understanding how bone strength is affected by low energy availability, weight gain and resumption of menses requires further investigations using 3-dimensional bone imaging techniques in order to improve the clinical management of the female athlete triad.

Estrogen and peptide YY are associated with bone mineral density in premenopausal exercising women

BACKGROUND

In women with anorexia nervosa, elevated fasting peptide YY (PYY) is associated with decreased bone mineral density (BMD). Prior research from our lab has demonstrated that fasting total PYY concentrations are elevated in exercising women with amenorrhea compared to ovulatory exercising women.

PURPOSE

The purpose of this study was to assess the association between fasting total PYY, average monthly estrogen exposure and BMD in non-obese premenopausal exercising women.

METHODS

Daily urine samples were collected and assessed for metabolites of estrone 1-glucuronide (E1G) and pregnandiol glucuronide (PdG) for at least one menstrual cycle if ovulatory or a 28-day monitoring period if amenorrheic. Fasting serum samples were pooled over the measurement period and analyzed for total PYY and leptin. BMD and body composition were assessed by dual-energy X-ray absorptiometry. Multiple regression analyses were performed to determine whether measures of body composition, estrogen status, exercise minutes, leptin and PYY explained a significant amount of the variance in BMD at multiple sites.

RESULTS

Premenopausal exercising women aged 23.8±0.9years with a mean BMI of 21.2±0.4kg/m(2) exercised 346±48min/week and had a peak oxygen uptake of 49.1±1.8mL/kg/min. Thirty-nine percent (17/44) of the women had amenorrhea. Fasting total PYY concentrations were negatively associated with total body BMD (p=0.033) and total hip BMD (p=0.043). Mean E1G concentrations were positively associated with total body BMD (p=0.033) and lumbar spine (L2-L4) BMD (p=0.047). The proportion of variance in lumbar spine (L2-L4) BMD explained by body weight and E1G cycle mean was 16.4% (R(2)=0.204, p=0.012). The proportion of variance in hip BMD explained by PYY cycle mean was 8.6% (R(2)=0.109, p=0.033). The proportion of variance in total body BMD explained by body weight and E1G cycle mean was 21.9% (R(2)=0.257, p=0.003).

CONCLUSION

PYY, mean E1G and body weight are associated with BMD in premenopausal exercising women. Thus, elevated PYY and suppressed estrogen concentrations are associated with, and could be directly contributing to, low BMD in exercising women with amenorrhea, despite regular physical activity.

Energy Balance, Myostatin, and GILZ: Factors Regulating Adipocyte Differentiation in Belly and Bone

Peroxisome proliferator-activated receptor gamma (PPAR-gamma) belongs to the nuclear hormone receptor subfamily of transcription factors. PPARs are expressed in key target tissues such as liver, fat, and muscle and thus they play a major role in the regulation of energy balance. Because of PPAR-gamma's role in energy balance, signals originating from the gut (e.g., GIP), fat (e.g., leptin), muscle (e.g., myostatin), or bone (e.g., GILZ) can in turn modulate PPAR expression and/or function. Of the two PPAR-gamma isoforms, PPAR-gamma2 is the key regulator of adipogenesis and also plays a role in bone development. Activation of this receptor favors adipocyte differentiation of mesenchymal stem cells, while inhibition of PPAR-gamma2 expression shifts the commitment towards the osteoblastogenic pathway. Clinically, activation of this receptor by antidiabetic agents of the thiazolidinedione class results in lower bone mass and increased fracture rates. We propose that inhibition of PPAR-gamma2 expression in mesenchymal stem cells by use of some of the hormones/factors mentioned above may be a useful therapeutic strategy to favor bone formation.

Increased serum adiponectin concentrations in amenorrheic physically active women are associated with impaired bone health but not with estrogen exposure

BACKGROUND

The role of adiponectin in mediating gonadal status and bone health in weight-stable healthy adult female athletes with secondary amenorrhea has not yet been described.

METHODS

Using a prospective observational study, age-matched premenopausal women were studied, including 1) sedentary ovulatory women (SedOv; n=10), 2) exercising ovulatory women (ExOv; n=15), and 3) exercising amenorrheic women (ExAmen; n=9). Primary outcome measures included serum total adiponectin and daily urinary estrogen (E1G) levels, expressed as area under the curve (AUC), body fat distribution, and bone mineral density (BMD). Serum leptin, ghrelin, total triiodothyronine (TT3), insulin, and resting energy expenditure (REE) were also determined.

RESULTS

The women in this study did not differ in age (25.3±1.4 years; mean ± SEM), height (164±1 cm), weight (57.7±1.0 kg) and BMI (21.5±0.4 kg/m(2)). Exercising women had a higher fat free mass (FFM), lower fat mass (FM) and lower serum leptin concentrations (p<0.05) compared to sedentary women. Adiponectin and ghrelin levels were higher (p<0.05), and TT3 (p=0.019), urinary E1G AUC (p=0.002) lower in ExAmen compared with ExOv and SedOv. Total and L1-L4 BMD were lower (p<0.05) in ExAmen compared with ExOv. Stepwise linear regression identified trunkal FM as the strongest predictor of log adiponectin adjusted for FM (F=23.54, p<0.001). L1-L4 BMD was predicted by log adiponectin and E1G AUC (F=9.856, p=0.045). Total BMD was predicted by log adiponectin (F=7.948, p=0.009). TT3 was the strongest predictor of E1G AUC (F=9.885, p=0.004).

CONCLUSIONS

Hypoestrogenic adult female athletes with secondary amenorrhea demonstrate elevated circulating adiponectin relative to FM in association with impaired bone health. Estrogen exposure was predicted by TT3, but not adiponectin. These findings suggest that nutritionally regulated hormones may mediate gonadal status, and that adiponectin and estrogen, either independently or in combination, may mediate bone health in adult amenorrheic physically active women.

Bone mineral density accrual determines energy expenditure with refeeding in anorexia nervosa and supersedes return of menses

Osteopenia and osteoporosis are major complications of anorexia nervosa (AN). Since bone is a tissue requiring large amounts of energy, we examined the disproportionate increase in resting energy expenditure (REE) that occurs with refeeding of AN patients to determine if it was related to bone accretion. Thirty-seven AN patients aged 23.4 ± 4.8 years underwent a behavioral weight-gain protocol lasting a median of 66 days; 27 remained amenorrheic, and 10 regained menses. Sixteen controls aged 25.1 ± 4.7 years were age- and % IBW matched with patients. REE was measured using a respiratory chamber-indirect calorimeter. Significant correlations were found between REE and changes in spine (r = 0.48, P < 0.02) and leg (r = 0.43, P < 0.05) BMDs in AN patients. Further subgroup analysis of the amenorrheics revealed significant correlation between REE and change in spine BMD (r = 0.59, P < 0.02) and higher IGF-1 after weight gain compared to controls. Amenorrheics also had lower BMDs. These findings were absent in the regained menses group. The increase in REE seen in women with AN during nutritional rehabilitation may be related to active bone formation, which is not as prominent when menses have returned.

The presence of both an energy deficiency and estrogen deficiency exacerbate alterations of bone metabolism in exercising women

BACKGROUND

Bone loss in amenorrheic athletes has been attributed to energy deficiency-related suppression of bone formation, but not increased resorption despite hypoestrogenism.

OBJECTIVE

To assess the independent and combined effects of energy deficiency and estrogen deficiency on bone turnover markers in exercising women.

DESIGN

PINP, osteocalcin, U-CTX-I, TT3, leptin, and ghrelin were measured repeatedly, and bone mineral density (BMD) was measured once in 44 exercising women. Resting energy expenditure (REE) was used to determine energy status (deficient or replete) and was corroborated with measures of metabolic hormones. Daily levels of urinary estrone and pregnanediol glucuronides (E1G, PdG), were assessed to determine menstrual and estrogen status. Volunteers were then retrospectively categorized into 4 groups: 1) Energy Replete+Estrogen Replete (EnR+E2R), (n=22), 2) Energy Replete+Estrogen Deficient (EnR+E2D), (n=7), 3) Energy Deficient+Estrogen Replete (EnD+E2R), (n=7), and 4) Energy Deficient+Estrogen Deficient (EnD+E2D), (n=8).

RESULTS

The groups were similar (p>0.05) with respect to age (24.05+/-1.75 yrs), weight (57.7+/-2.2 kg), and BMI (21.05+/-0.7 kg/m2). By design, REE/FFM (p=0.028) and REE:pREE (p<0.001) were lower in the EnD vs. EnR group, and the E2D group had a lower REE:pREE (p=0.005) compared to the E2R group. The EnD+E2D group had suppressed PINP (p=0.034), and elevated U-CTX-I (p=0.052) and ghrelin (p=0.028) levels compared to the other groups. These same women also had convincing evidence of energy conservation, including TT3 levels that were 29% lower (p=0.057) and ghrelin levels that were 44% higher (p=0.028) than that observed in the other groups. Energy deficiency was associated with suppressed osteocalcin, and TT3 (p<0.05), whereas estrogen deficiency was associated with decreased E1G (p<0.02), and lower L2-L4 BMD (p=0.033). Leptin was significant in predicting markers of bone formation, but not markers of bone resorption.

CONCLUSIONS

When the energy status of exercising women was adequate (replete), there were no apparent perturbations of bone formation or resorption, regardless of estrogen status. Estrogen deficiency in exercising women, in the presence of an energy deficiency, was associated with bone loss and involved suppressed bone formation and increased bone resorption. These findings underscore the importance of avoiding energy deficiency, which is associated with hypoestrogenism, to avoid bone health problems.

Caloric restriction decreases cortical bone mass but spares trabecular bone in the mouse skeleton: implications for the regulation of bone mass by body weight

INTRODUCTION

Body weight is positively correlated with bone mass and density, and both muscle mass and body fat are thought to play a role in regulating bone metabolism. We examined bone metabolism in calorically restricted mice to determine how alterations in soft tissue mass affect bone mass, density, and strength.

MATERIALS AND METHODS

Caloric restriction (CR) was initiated in male mice at 14 wk of age at 10% restriction, increased to 25% restriction at 15 wk, and then increased to 40% restriction at 16 wk, where it was maintained until 24 wk of age when the study was terminated. Control mice were fed ad libitum (AL). Body composition, BMD, and BMC were measured by DXA, BMD and BMC in the femoral metaphysis were measured by pQCT, femora were tested in three-point bending, serum leptin and IGF-1 were measured using immunoassay, and osteoblast and osteoclast numbers were determined using histomorphometry.

RESULTS

Body weight, lean mass, fat mass, percent body fat, serum leptin, and serum IGF-1 were all significantly lower in CR mice than AL mice. Whole body BMC and BMD did not differ significantly between the two groups. Femur BMC, BMD, cortical thickness, and fracture strength decreased significantly in CR mice, but trabecular bone volume fraction in the femur did not change with food restriction. Vertebral cortical thickness also decreased with caloric restriction, whereas spine BMC, BMD, and trabecular bone volume fraction were significantly increased with caloric restriction.

CONCLUSIONS

Caloric restriction and its related weight reduction are associated with marked decreases in lean mass, fat mass, serum leptin and IGF-1, and cortical bone mass. Consistent with the opposite effects of leptin on cortical and cancellous bone, trabecular bone mass is spared during food restriction.

Treatment of anorexia nervosa is associated with increases in bone mineral density, and recovery is a biphasic process involving both nutrition and return of menses

BACKGROUND

Recovery from osteoporosis in anorexia nervosa (AN) is uncertain.

OBJECTIVE

The purpose of this study was to understand the changes in bone mineral density (BMD) in women with AN and the mechanisms of recovery from osteopenia.

DESIGN

We studied BMD and markers of bone formation and resorption, osteocalcin and N-telopeptide (NTX), in patients with AN (n=28) who were following a behavioral weight-gain protocol.

RESULTS

Anorexic patients experienced significant percentage increases in BMD (4.38 +/- 7.48% for spine; 3.77 +/- 8.8% for hip; P<0.05 for both) from admission until recovery of 90% ideal body weight, achieved over 2.2 mo. NTX concentrations were higher in patients with AN at admission than in healthy control subjects (n=11; 69.0 +/- 31.09 and 48.3 +/- 14.38 nmol/mmol creatinine, respectively; P<0.05) and in reference control subjects (n=30; 69.0 +/- 31.09 and 37.0+/-6.00 nmol/mmol creatinine, respectively; P<0.001). In weight-recovered subjects with AN, osteocalcin increased (from 8.0 +/- 3.05 to 11.2 +/- 6.54 ng/mL; P<0.05), whereas NTX remained elevated (from 69.0 +/- 31.09 to 66.7 +/- 45.5 nmol/mmol creatinine; NS). A decrease in NTX (from 70.7 +/- 40.84 to 45.9 +/- 22.72 nmol/mmol creatinine; NS) occurred only in the subgroup of subjects who regained menses with weight recovery.

CONCLUSIONS

Nutritional rehabilitation induces a powerful anabolic effect on bone. However, a fall of NTX and a shift from the dominant resorptive state, which we postulate involves full recovery, may involve a hormonal mechanism and require a return of menses. Nutritional rehabilitation appears to be critical to bone recovery and may explain the ineffectiveness of estrogen treatment alone on BMD in the cachectic state.

Preserved Bone Health in Adolescent Elite Rhythmic Gymnasts despite Hypoleptinemia

BACKGROUND/AIMS

Leptin is linked to hormonal disturbances occurring in anorexia and positively linked with bone mineral density. The aim of this study was to determine whether hypoleptinemia occurring in rhythmic gymnasts may affect bone health.

METHOD

Leptin, insulin, cortisol, IGF1 levels and bone markers were determined in 36 rhythmic gymnasts (EG) and 20 controls (C). Body composition, BMD at the whole body (WBBMD), lumbar spine (LSBMD) and bone ultrasound properties (SOS, BUA) were measured.

RESULTS

The rhythmic gymnasts had lower fat mass and leptin level than the controls. There was no difference for IGF1, cortisol and insulin levels. Bone turnover rate was higher in elite gymnasts. The uncoupling index showed that remodeling favored the bone formation. LSBMD, WBBMD, SOS and BUA were higher in elite gymnasts after adjustment for fat mass. Leptin correlated positively with fat mass and negatively with physical activity.

CONCLUSION

High impact training is able to counterbalance bone effects usually encountered in hormonally disturbed subjects. Our results suggest that hypoleptinaemia might be related to direct osteogenic effects and indirect hormonal mechanisms including preservation of IGF and cortisol levels.

The endeavor of high maintenance homeostasis: resting metabolic rate and the legacy of longevity

Metabolism, the continuous conversion between structural molecules and energy, is life in essence. Size, metabolic rate, and maximum life span appear to be inextricably interconnected in all biological organisms and almost follow a "universal" law. The notion of metabolic rate as the natural "rate of living" filled most of the academic discussion on aging in the early 20th century to be later replaced by the free-radical theory of aging. We argue that the rate of living theory was discarded too quickly and that studying factors affecting resting metabolic rate during the aging process may provide great insight into the core mechanisms explaining differential longevity between individuals, and possibly the process leading to frailty. We predict that measures of resting metabolic rate will be introduced in geriatric clinical practice to gather information on the degree of multisystem dysregulation, exhaustion of energy reserve, and risk of irreversible frailty.

The psychobiology and diagnostic significance of amenorrhea in patients with anorexia nervosa

Amenorrhea is a diagnostic criterion for anorexia nervosa (AN), although menstrual cycles have been found to persist in some women with all the other features of AN. This study sought to determine factors that are associated with amenorrhea in 39 women with current primary spectrum AN. The use of exercise to control weight (odds ratio (OR) = 3.5; 95% confidence interval (CI) = 1.3-9.9; P = .02), low novelty seeking scores (OR = 0.7; 95% CI = 0.58-0.94; P = .02), and low systolic blood pressure (OR = 0.9; 95% CI = 0.84-0.99; P = .046) were predictors of amenorrhea independent of body mass index.

Physical activity in the prevention and amelioration of osteoporosis in women : interaction of mechanical, hormonal and dietary factors

Osteoporosis is a serious health problem that diminishes quality of life and levies a financial burden on those who fear and experience bone fractures. Physical activity as a way to prevent osteoporosis is based on evidence that it can regulate bone maintenance and stimulate bone formation including the accumulation of mineral, in addition to strengthening muscles, improving balance, and thus reducing the overall risk of falls and fractures. Currently, our understanding of how to use exercise effectively in the prevention of osteoporosis is incomplete. It is uncertain whether exercise will help accumulate more overall peak bone mass during childhood, adolescence and young adulthood. Also, the consistent effectiveness of exercise to increase bone mass, or at least arrest the loss of bone mass after menopause, is also in question. Within this framework, section 1 introduces mechanical characteristics of bones to assist the reader in understanding their responses to physical activity. Section 2 reviews hormonal, nutritional and mechanical factors necessary for the growth of bones in length, width and mineral content that produce peak bone mass in the course of childhood and adolescence using a large sample of healthy Caucasian girls and female adolescents for reference. Effectiveness of exercise is evaluated throughout using absolute changes in bone with the underlying assumption that useful exercise should produce changes that approximate or exceed the absolute magnitude of bone parameters in a healthy reference population. Physical activity increases growth in width and mineral content of bones in girls and adolescent females, particularly when it is initiated before puberty, carried out in volumes and at intensities seen in athletes, and accompanied by adequate caloric and calcium intakes. Similar increases are seen in young women following the termination of statural growth in response to athletic training, but not to more limited levels of physical activity characteristic of longitudinal training studies. After 9-12 months of regular exercise, young adult women often show very small benefits to bone health, possibly because of large subject attrition rates, inadequate exercise intensity, duration or frequency, or because at this stage of life accumulation of bone mass may be at its natural peak. The important influence of hormones as well as dietary and specific nutrient abundance on bone growth and health are emphasised, and premature bone loss associated with dietary restriction and estradiol withdrawal in exercise-induced amenorrhoea is described. In section 3, the same assessment is applied to the effects of physical activity in postmenopausal women. Studies of postmenopausal women are presented from the perspective of limitations of the capacity of the skeleton to adapt to mechanical stress of exercise due to altered hormonal status and inadequate intake of specific nutrients. After menopause, effectiveness of exercise to increase bone mineral depends heavily on adequate availability of dietary calcium. Relatively infrequent evidence that physical activity prevents bone loss or increases bone mineral after menopause may be a consequence of inadequate calcium availability or low intensity of exercise in training studies. Several studies with postmenopausal women show modest increases in bone mineral toward the norm seen in a healthy population in response to high-intensity training. Physical activities continue to stimulate increases in bone diameter throughout the lifespan. These exercise-stimulated increases in bone diameter diminish the risk of fractures by mechanically counteracting the thinning of bones and increases in bone porosity. Seven principles of bone adaptation to mechanical stress are reviewed in section 4 to suggest how exercise by human subjects could be made more effective. They posit that exercise should: (i) be dynamic, not static; (ii) exceed a threshold intensity; (iii) exceed a threshold strain frequency; (iv) be relatively brief but intermittent; (v) impose an unusual loading pattern on the bones; (vi) be supported by unlimited nutrient energy; and (vii) include adequate calcium and cholecalciferol (vitamin D3) availability.

Leptin treatment induces loss of bone marrow adipocytes and increases bone formation in leptin-deficient ob/ob mice

Normal mice and leptin-deficient ob/ob mice were treated with leptin to study effects on osteogenesis and adipogenesis in bone marrow. Leptin treatment significantly decreased bone marrow adipocyte size and number in ob/ob mice while increasing bone formation, BMC, and BMD. The results suggest that, in leptin-sensitive animals, the reduction in marrow adipocytes has positive effects on bone formation.

INTRODUCTION

Adipocytes, osteoblasts, and osteoclasts have leptin receptors, and leptin can also affect bone metabolism indirectly through its receptors in the hypothalamus. We examined the effects of leptin treatment on bone formation, BMD, and marrow adipocyte population in normal mice and leptin-deficient ob/ob mice.

MATERIALS AND METHODS

At the age of 15 weeks, mice were implanted with Alzet osmotic pumps for subcutaneous delivery of treatment solutions (saline, 2.5 microg leptin/day, or 10 microg leptin/day) for 14 days at a delivery rate of 0.25 microl/h. Bone formation was assessed using fluorochrome labels, cell populations were quantified using histomorphometry, and bone densitometry was measured using DXA. We also used a Luminex Beadlyte assay system to quantify cell survival markers in bone marrow samples.

RESULTS AND CONCLUSIONS

Results indicate that both doses of leptin decreased the number of marrow adipocytes in ob/ob mice by >20% (p < 0.05) compared with PBS-treated ob/ob mice. The decrease in adipocyte number with leptin treatment is accompanied by an increase in concentration of the apoptosis marker caspase-3 in bone marrow adipocytes and hematopoietic cells. Both leptin doses also significantly (p < 0.05) increased the percentage of fluorochrome-labeled tibial endosteal surface by >30% compared with PBS-treated ob/ob mice. Leptin treatment increased whole body BMC by >30% in the ob/ob mice receiving the highest leptin dose. Leptin treatment provided no increase in bone formation, BMC, or BMD in normal, leptin-replete mice.

Physiological aspects and clinical sequelae of energy deficiency and hypoestrogenism in exercising women

Amenorrhoea associated with reduced caloric intake and strenuous exercise leads to hypoestrogenism and is associated with clinical manifestations that include disordered eating, stress fractures, osteoporosis, and, as recently reported, a potential increase in the risk of premature cardiovascular disease. Disordered eating, menstrual irregularities and bone loss comprise the clinical condition known as the 'female athlete triad'. The aetiology of the triad is linked to a high prevalence of disordered eating and cognitive restraint. This results in inadequate caloric intake for high exercise energy expenditures that leads to energy deficiency. This in turn stimulates compensatory mechanisms, such as weight loss or energy conservation, subsequently causing a central suppression of reproductive function and concomitant hypoestrogenism. Because the aetiology of menstrual disturbances and the female athlete triad is causally linked to energy deficiency, there is no justification for fears that exercise itself is unhealthy for women. However, improved detection, monitoring, and treatment of all components of the triad in exercising women should be emphasized. This paper critically reviews the physiological aspects and clinical sequelae of energy deficiency and hypoestrogenism associated with the female athlete triad in exercising women.

Sports and performing arts medicine. 6. Issues relating to dancers

This self-directed study module highlights biomechanics unique to dance that predispose to common injuries of the lower extremity and discusses preventative strategies. It is part of the study guide on sports and performing arts medicine in the Self-Directed Physiatric Education Program for practitioners and trainees in physical medicine and rehabilitation.

OVERALL ARTICLE OBJECTIVE

To summarize lower-limb and back injuries commonly seen in dancers.

The Dancer as a Performing Athlete

The physical demands placed on dancers from current choreography and performance schedules make their physiology and fitness just as important as skill development. However, even at the height of their professional careers, dancers' aerobic power, muscular strength, muscular balance, bone and joint integrity are the 'Achilles heels' of the dance-only selection and training system. This partly reflects the unfounded view, shared by sections of the dance world, that any exercise training that is not directly related to dance would diminish dancers' aesthetic appearances. Given that performing dance itself elicits only limited stimuli for positive fitness adaptations, it is not surprising that professional dancers often demonstrate values similar to those obtained from healthy sedentary individuals of comparable age in key fitness-related parameters. In contrast, recent data on male and female dancers revealed that supplementary exercise training can lead to improvements of such fitness parameters and reduce incidents of dance injuries, without interfering with key artistic and aesthetic requirements. It seems, however, that strict selection and training regimens have succeeded in transforming dance to an activity practised by individuals who have selectively developed different flexibility characteristics compared with athletes. Bodyweight targets are normally met by low energy intakes, with female dance students and professional ballerinas reported to consume below 70% and 80% of the recommended daily allowance of energy intake, respectively, while the female athlete 'triad' of disordered eating, amenorrhoea and osteoporosis is now well recognised and is seen just as commonly in dancers. An awareness of these factors will assist dancers and their teachers to improve training techniques, to employ effective injury prevention strategies and to determine better physical conditioning. However, any change in the traditional training regimes must be approached cautiously to ensure that the aesthetic content of the dance is not affected by new training techniques. Since physiological aspects of performing dance have been viewed primarily in the context of ballet, further scientific research on all forms of dance is required.

Exercise-induced endocrine pathologies

There has been a substantial increase in women practicing sports over the past 30 yr. While exercise provides many health benefits, there appears to be a unique set of risks associated with intense exercise for the female athlete. The female athlete triad encompasses these risks, including amenorrhea, osteoporosis and eating disorders. The incidence of menstrual irregularities including primary and secondary amenorrhea and shortened luteal phases is much higher among women partaking in athletics, specifically in sports requiring low body weight for performance and aesthetics. The hormone pattern seen in these amenorrheic athletes includes a decrease in GnRH pulses from the hypothalamus, which results in decreased pulsatile secretion of LH and FSH and shuts down stimulation of the ovary. The recently discovered hormone leptin may also play a large role as a significant mediator of reproductive function. The prevalence of eating disorders is high among female athletes who practice sports which emphasize leanness. Consequently, the cause of menstrual irregularities is not due to the exercise alone, but to chronic inadequate or restrictive caloric intake that does not compensate for the energy expenditure. The most dangerous risk associated with amenorrhea for the female athlete is the impact on the skeleton. Complications associated with amenorrhea include compromised bone density, failure to attain peak bone mass in adolescence and increased risk of stress fractures. The diagnosis of exercise-associated menstrual dysfunctions is one of exclusion. The most effective treatment is to decrease the intensity of the exercise and increase the nutritional intake. Hormone replacement has also been under investigation as a possible treatment.

Determinants of bone density in 30- to 65-year-old women: a co-twin study

Reported effects of body composition and lifestyle on bone mineral density in pre-elderly adult women have been inconsistent. In a co-twin study, we measured bone mineral density, lean and fat mass, and lifestyle factors. Analyzing within pair differences, we found negative associations between bone mineral density and tobacco use (2.3-3.3% per 10 pack-years) and positive associations with sporting activity and lean and fat mass.

INTRODUCTION

Reported effects of body composition and lifestyle of bone mineral density in pre-elderly adult women have been inconsistent.

METHODS

In a co-twin study of 146 female twin pairs aged 30 to 65 years, DXA was used to measure bone mineral density at the lumbar spine, total hip, and forearm, total body bone mineral content, and lean and fat mass. Height and weight were measured. Menopausal status, dietary calcium intake, physical activity, current tobacco use, and alcohol consumption were determined by questionnaire. Within-pair differences in bone measures were regressed through the origin against within-pair differences in putative determinants.

RESULTS

Lean mass and fat mass were associated with greater bone mass at all sites. A discordance of 10 pack-years smoking was related to a 2.3-3.3% (SE, 0.8-1.0) decrease in bone density at all sites except the forearm, with the effects more evident in postmenopausal women. In all women, a 0.8% (SE, 0.3) difference in hip bone mineral density was associated with each hour per week difference in sporting activity, with effects more evident in premenopausal women. Daily dietary calcium intake was related to total body bone mineral content and forearm bone mineral density (1.4 +/- 0.7% increase for every 1000 mg). Lifetime alcohol consumption and walking were not consistently related to bone mass.

CONCLUSION

Several lifestyle and dietary factors, in particular tobacco use, were related to bone mineral density. Effect sizes varied by site. Characterization of determinants of bone mineral density in midlife and thereafter may lead to interventions that could minimize postmenopausal bone loss and reduce osteoporotic fracture risk.

Persistent osteopenia in ballet dancers with amenorrhea and delayed menarche despite hormone therapy: a longitudinal study

OBJECTIVE

To investigate the role of estrogen deprivation and replacement in amenorrheic and nonamenorrheic dancers on hormone therapy and calcium.

DESIGN

Clinical, placebo-controlled, randomized trial study.Healthy volunteers in an academic research environment.

PATIENT(S)

Fifty-five dancers (mean age: 22.0 +/- 4.6, age at menarche: 14.7 +/- 2.3 years), including 24 amenorrheics.

INTERVENTION(S)

Amenorrheics were randomized in a controlled trial to receive placebo or Premarin, 0.625 mg for 25 days monthly, with Provera, 10 mg, for 10 of these 25 days (hormone therapy) for 2 years. These women were compared to normally menstruating controls. The study participants also received 1250 mg of calcium per day.

MAIN OUTCOME MEASURE(S)

Bone mineral density (BMD) measured at the foot, wrist, and lumbar spine. Our overall results showed no difference in BMD between the treated or placebo groups, indicating that hormone therapy did not change or normalize BMD when compared to normals. Five patients (all on placebo) who resumed menses during the study showed an increase in BMD without normalization.

CONCLUSION(S)

These findings suggest that mechanisms other than hypoestrogenism may be involved with the osteopenia associated with exercise-induced amenorrhea.

A unified model for the action of leptin on bone turnover

Leptin has been advocated as a centrally acting factor responsible for inhibiting accumulation of bone mass. However, recent investigations unequivocally establish leptin as a local (autocrine) factor expressed by osteoblasts. Exogenously added leptin causes osteoblastic cell proliferation and differentiation, while also rendering osteoblasts more efficacious in terms of mineralization. Leptin acts as an anti-apoptotic agent, and augments messages responsible for the remodelling of bone tissue, i.e., mRNAs for osteoprotegerin (OPG) and the interleukin IL-6. Furthermore, leptin message is readily expressed in osteoblasts subjected to mechanical strain. In this respect, osteoblasts, which are unilaterally stretched proliferate and differentiate, a phenomenon being potentiated by exposure of the cells to differentiating humoral factors. This article discusses a unified model of dually acting leptin through the central nervous system and the mechanostat principle applied to osteoblasts. The proposed model may account for the finely tuned bone homeostasis maintained within rather narrow limits, depending on exposure to humoral factors and the prevailing mechanostat usage mode.