Anemia, iron deficiency, and stress fractures in female combatants during 16 months

Systematic Review and Meta-Analysis: Iron Deficiency and Iron Deficiency Anemia Among Military Recruits Undergoing Basic Combat Training

INTRODUCTION

The first period of military service consists of a physically and mentally challenging basic combat training (BCT) program. Factors like demanding physical exercise, limited recovery time, and restricted diet choice and food intake may challenge iron intake and homeostasis in recruits undergoing BCT. Iron-deficient individuals may experience reduced work capacity, fatigue, weakness, frequent infections, and increased injury risk. Limited knowledge is available on the extent of this potential health risk among military recruits. The aim of the present study was to systematically review published studies on the prevalence and change in prevalence of anemia, iron deficiency (ID), and ID anemia (IDA) among recruits undergoing BCT.

MATERIALS AND METHODS

Electronic searches were conducted in the databases Medline (Ovid), Embase (Embase.com), and Web of Science (Clarivate Analytics) from database inception up until April 16, 2024. Inclusion criteria were observational studies with both cross-sectional and observational longitudinal designs that examined the effects of BCT (intervention) on iron status (outcome) in military recruits (population). Extracted data were the number of participants (n), age, sex, country/population, BCT duration, and relevant measures of prevalence and changes in prevalence of anemia, ID, and IDA (primary outcome) and physical performance, mood state, stress fractures, attrition rate, and nutritional supplements (secondary outcomes). The study quality and risk of bias were assessed using the JBI Critical Appraisal Checklist for Studies Reporting Prevalence Data and The National Institutes of Health Quality Assessment Tool for Before-After (Pre-Post) Studies With No Control Group. Meta-analyses were performed using restricted maximum-likelihood models, and the effect size was calculated as Cohen's h with 95% CI.

RESULTS

Twenty-two articles were systematically reviewed (n = 111,764 men and 12,650 women), and six of these papers (n = 388 men and 773 women) were included in the meta-analysis. There was a varying prevalence of anemia, ID, and IDA among military recruits at the start of BCT. Results from meta-analyses showed negligible and nonsignificant effects of BCT on the prevalence of anemia, ID, and IDA. The quality of the included cross-sectional studies ranging from fair to good, whereas a large proportion of the included longitudinal studies were classified as poor. No sign of publication bias was found.

CONCLUSIONS

The prevalence of anemia, ID, and IDA in military recruits seems not to be affected by the completion of BCT shorter than 16 weeks, whereas the effects of longer BCT durations remain unclear. Even though body iron homeostasis seems unaffected, adequate energy and nutritional intake should remain a priority. Future research could focus on dietary interventions to determine the optimal diet among female recruits in specifically exposed populations.

Micronutrient Status During Military Training and Associations With Musculoskeletal Health, Injury, and Readiness Outcomes

OBJECTIVE

Micronutrient status, specifically vitamin D and iron, represent modifiable factors for optimizing military readiness. The primary purpose of this investigation was to determine associations between micronutrient deficiency (i.e., iron status and 25-hydroxy-vitamin D [25(OH)D]) and operationally relevant outcomes (i.e., skeletal health, musculoskeletal injury) at baseline and post-10 weeks of arduous military training.

METHODS

A total of 227 (177 men, 50 women) Marine Officer Candidates School (OCS) candidates who completed OCS training with complete data sets were included in this analysis. Vitamin D and iron status indicators were collected at two timepoints, pre (baseline) and post OCS. Musculoskeletal outcomes at the mid- and proximal tibial diaphysis were assessed via peripheral quantitative computed tomography.

RESULTS

Micronutrient status declined following OCS training in men and women and was associated with musculoskeletal outcomes including greater bone strength (strength strain index) at the mid-diaphysis site in those with optimal status (M = 38.26 mm3, SE = 15.59) versus those without (M = -8.03 mm3, SE = 17.27). In women (p = .037), endosteal circumference was greater in the deficient group (M = 53.26 mm, SE = 1.19) compared with the optimal group (M = 49.47 mm, SE = 1.31) at the proximal diaphysis. In men, greater baseline hepcidin concentrations were associated with an increased likelihood of suffering musculoskeletal injury during training.

CONCLUSIONS

Vitamin D and iron status declined over the course of training, suggesting impaired micronutrient status. Differences in musculoskeletal outcomes by micronutrient group suggests optimal vitamin D and ferritin concentrations may exert beneficial effects on bone fatigability and fracture reduction during military training.

Nutritional Indicators of Bone Nonunion: A Systematic Review

Background/Objectives: Bone nonunion remains a clinical challenge in orthopedic surgery with significant impacts on mental and physical wellbeing for patients. There are several previously established risk factors of nonunion that are connected to nutrition, but this has yet to be substantially explored. This review seeks to assess all studies that present associations between nutrition and nonunion to understand the potential for clinical relevance in nonunion prevention. Methods: Case-control and cohort studies comparing nonunion risk based on nutritional factors were gathered through PubMed in July 2024. Data were extracted with dual verification through Covidence and assessed for bias using the Newcastle-Ottawa Scale. Results: A total of 21 studies were included in this literature review. Vitamin D deficiency was a significant risk factor of nonunion in six studies and not significant in six other studies. Albumin was significant in three of the five studies addressing this lab value. Iron deficiency anemia was significant in a study assessing its impact on nonunion. Calcium was not significant in the one study mentioned. ICD-10-coded malnutrition was significant in one of the two studies. Sarcopenia, nutritional care plans, and dietitian-diagnosed malnutrition were statistically significant clinical indicators for predicting nonunion, but food insecurity was insignificant. Conclusions: Vitamin D, calcium, albumin, iron deficiency anemia, sarcopenia, and clinically diagnosed malnutrition have all been associated with an increased risk of nonunion in observational studies and should be considered when preventing nonunion development.

Relative Energy Deficiency in Sport (REDs): Endocrine Manifestations, Pathophysiology and Treatments

Research on lean, energy-deficient athletic and military cohorts has broadened the concept of the Female Athlete Triad into the Relative Energy Deficiency in Sport (REDs) syndrome. REDs represents a spectrum of abnormalities induced by low energy availability (LEA), which serves as the underlying cause of all symptoms described within the REDs concept, affecting exercising populations of either biological sex. Both short- and long-term LEA, in conjunction with other moderating factors, may produce a multitude of maladaptive changes that impair various physiological systems and adversely affect health, well-being, and sport performance. Consequently, the comprehensive definition of REDs encompasses a broad spectrum of physiological sequelae and adverse clinical outcomes related to LEA, such as neuroendocrine, bone, immune, and hematological effects, ultimately resulting in compromised health and performance. In this review, we discuss the pathophysiology of REDs and associated disorders. We briefly examine current treatment recommendations for REDs, primarily focusing on nonpharmacological, behavioral, and lifestyle modifications that target its underlying cause-energy deficit. We also discuss treatment approaches aimed at managing symptoms, such as menstrual dysfunction and bone stress injuries, and explore potential novel treatments that target the underlying physiology, emphasizing the roles of leptin and the activin-follistatin-inhibin axis, the roles of which remain to be fully elucidated, in the pathophysiology and management of REDs. In the near future, novel therapies leveraging our emerging understanding of molecules and physiological axes underlying energy availability or lack thereof may restore LEA-related abnormalities, thus preventing and/or treating REDs-related health complications, such as stress fractures, and improving performance.

Multivitamin Compliance Reduces Injuries of Female Recruits at Air Force Basic Training: A Randomized Controlled Cohort Study

INTRODUCTION

Department of the Air Force basic military training (BMT) is the 7.5-week initial entry training for all enlisting U.S. Air Force and Space Force recruits. Overuse musculoskeletal injuries (MSKI) during training threaten success in BMT, and trainees with nutritional deficiencies are at higher risk. Several efforts are made at BMT to mitigate these issues to help trainees graduate on time, such as the distribution of multivitamins (MVI) to female recruits. However, trainee compliance with the prescribed MVI has been reported to be low, calling into question the effectiveness of this intervention. This study evaluated the effect of briefing modality offered to these trainees at the time of distribution on educational effectiveness, MVI compliance, and injury rates.

MATERIALS AND METHODS

This was a randomized controlled cohort study of BMT female trainees. Subjects included all female trainees of a single iteration of BMT concurrently completing training within the same squadron. At the outset of training, cohorts were randomly educated in one of two ways regarding the provided MVI. The control cohort (n = 80) was presented with the standard educational video created by BMT-registered dietitians, while the test cohort (n = 79) was presented the video and then also briefed in-person by a group of subject matter experts. At the end of BMT, the trainees completed a questionnaire regarding their knowledge, confidence, and compliance with the MVI. Additionally, a routinely collected training database was queried and analyzed for differences in injuries and training outcomes using the chi-squared test with significance set to α ≤ 0.05.

RESULTS

Although both cohorts found their educational presentation useful, the "in-person" cohort reported significantly higher compliance rates and were found to be diagnosed with MSKI and bone stress injuries at significantly lower rates (43% and 66% relative risk reductions, respectively).

CONCLUSIONS

Education to female BMT trainees regarding the MVI, which included a face-to-face discussion with subject matter experts, resulted in greater compliance and reduced incidence of MSKI and bone stress injury, compared to a video prepared by registered dietitians alone. Such educational approaches should continue to be strived for in this and other military population health measures. This study's implication of MVI efficacy for injury risk reduction in female trainees should be further studied, verified, and improved upon in this and other populations.

Changes in haemoglobin and ferritin levels during basic combat training: relevance for attrition and injury frequency

INTRODUCTION

The primary aim of the present study was to assess interindividual and intraindividual variations in haemoglobin and ferritin concentrations in Swedish recruits over 5 months of basic combat training (BCT). The secondary aim was to find predictors for missing training (a precursor for attrition) and overuse injuries during BCT.

METHODS

In a cohort design, a total of 58 female and 104 male recruits provided complete data. We assessed the ferritin concentrations and haemoglobin concentrations at baseline and after 5 months of BCT and physical work capacity at baseline.

RESULTS

During BCT, haemoglobin concentrations increased significantly in both females and males. Ferritin concentrations decreased significantly in both sexes and the prevalence of iron deficiency (ID) (ie, ferritin levels <30 µg/L) increased significantly in females. The physical work capacity at baseline was related to the risk of missing training in fully adjusted models. In gender-adjusted analyses, baseline ferritin was related to the risk of overuse injury, but neither baseline nor change in iron status was related to injuries or risk of missing training when controlling for confounders. Body mass increased significantly in both genders, but we found no correlation between individual change in body mass and change in haemoglobin or ferritin nor was change in body mass related to the risk of overuse injury or missing training.

CONCLUSION

In the present study, the prevalence of ID increased over the course of 5 months, while haemoglobin concentrations increased. As baseline physical work capacity was related to missing training, there are reasons to support preparatory physical training before BCT. These findings may inform future preventive interventions aimed at preventing detrimental effects of ID.

Sex differences in iron status during military training: a prospective cohort study of longitudinal changes and associations with endurance performance and musculoskeletal outcomes

This study investigated sex differences in Fe status, and associations between Fe status and endurance and musculoskeletal outcomes, in military training. In total, 2277 British Army trainees (581 women) participated. Fe markers and endurance performance (2·4 km run) were measured at the start (week 1) and end (week 13) of training. Whole-body areal body mineral density (aBMD) and markers of bone metabolism were measured at week 1. Injuries during training were recorded. Training decreased Hb in men and women (mean change (-0·1 (95 % CI -0·2, -0·0) and -0·7 (95 % CI -0·9, -0·6) g/dl, both P < 0·001) but more so in women (P < 0·001). Ferritin decreased in men and women (-27 (95 % CI -28, -23) and -5 (95 % CI -8, -1) µg/l, both P ≤ 0·001) but more so in men (P < 0·001). Soluble transferrin receptor increased in men and women (2·9 (95 % CI 2·3, 3·6) and 3·8 (95 % CI 2·7, 4·9) nmol/l, both P < 0·001), with no difference between sexes (P = 0·872). Erythrocyte distribution width increased in men (0·3 (95 % CI 0·2, 0·4)%, P < 0·001) but not in women (0·1 (95 % CI -0·1, 0·2)%, P = 0·956). Mean corpuscular volume decreased in men (-1·5 (95 % CI -1·8, -1·1) fL, P < 0·001) but not in women (0·4 (95 % CI -0·4, 1·3) fL, P = 0·087). Lower ferritin was associated with slower 2·4 km run time (P = 0·018), sustaining a lower limb overuse injury (P = 0·048), lower aBMD (P = 0·021) and higher beta C-telopeptide cross-links of type 1 collagen and procollagen type 1 N-terminal propeptide (both P < 0·001) controlling for sex. Improving Fe stores before training may protect Hb in women and improve endurance and protect against injury.

Compliance compromises an interventional study on iron supplementation in female combatants

INTRODUCTION

Low iron levels are related to overuse injuries, poor physical performance and cognitive impairments in female recruits. The aim of this study was to evaluate iron supplement compliance in female combatants during basic training, and its effect on haemoglobin (Hgb), ferritin and injuries.

METHODS

329 female recruits to light infantry units filled induction questionnaires regarding smoking status, previous overuse injuries and iron deficiency. Blood was drawn for Hgb and ferritin. Subjects with ferritin levels below 20 ng/mL were considered iron depleted and were prescribed a ferrous fumarate supplement. After 4 months of basic training, the subjects completed a follow-up questionnaire regarding overuse injuries, reasons for failure to complete basic training and compliance with iron supplementation. Blood tests were repeated.

RESULTS

Mean ferritin levels declined during training (from 18.1±18.2 to 15.3±9.6, p=0.01). Compliance with iron supplementation was observed in 26 (26.3%) of the subjects. In compliant subjects, Hgb levels remained constant and ferritin levels increased by 2.9±5.4 (p=0.07). The main reasons for reported non-compliance were forgetfulness, 26 (35.6%), and gastrointestinal side effects, 17 (23.3%). Injuries during training were not found to be associated with iron status. Smokers had a significantly higher rate of reported injuries prior to training (p<0.01).

CONCLUSIONS

Ferritin levels decline during training. Compliance with iron supplementation is low. Iron supplementation has a significant effect on ferritin levels, even in the non-compliance group. Injuries were not related to iron status in this group. Further research is needed in order to clarify the most appropriate iron supplementation method.

Part II: Risk Factors for Stress Fractures in Female Military Recruits

INTRODUCTION

Stress fractures (SFx) represent a significant proportion of injuries in military recruits internationally. Stress fractures disproportionately affect female recruits, a disparity that has similarly been consistently demonstrated in female athletes. Stress fractures result in medical morbidity, financial burden, and medical discharge from military service. This review presents current literature regarding SFx risk factors to identify and/or mitigate in this high-risk population.

METHODS

A literature review was conducted using PubMed to find relevant articles. We utilized keywords stress fracture, military, recruits, female, risk factors, modifiable, non-modifiable, overuse, nutrition, and/or prevention. Articles older than 10 years (published before 2010) were not considered. Review articles were considered, but if a research article was cited by a review, the research was included directly. Articles with primary military data, members of the military as subjects, especially when female recruits were included, were strongly considered for inclusion in this review.

RESULTS

Modifiable risk factors for SFx include nutritional deficiency, especially of iron, vitamin D, and possibly calcium, poor physical fitness, suboptimal training programming for injury development and recovery, load carriage, and military footwear. Non-modifiable risk factors include female sex, greater height, lower weight and body mass index in females but lower or higher weight and body mass index in males, lower body fat percentage, and lower bone mineral density. In addition, menstrual dysfunction, low energy availability, later age at menarche, and iron deficiency pose unique risks to female recruits. Preventive measures include leadership education, programs with recovery considerations, and risk factor screening.

CONCLUSION

This review, Part II of a two-part series, guides multidisciplinary management of military recruits, especially females, who are at risk for developing SFx. Unique nuances of the military recruit require specific knowledge to reduce high incidence rates of injury internationally.

Part I: Background and Clinical Considerations for Stress Fractures in Female Military Recruits

INTRODUCTION

Stress fractures (SFx) represent a significant proportion of musculoskeletal injuries in military recruits internationally. Incidence rates as high as 40% have been reported, varying by country and branch of military cohorts. Tibial SFx are the most common, followed by other lower extremity sites, and are related to the emphasis on running during training. SFx disproportionately affect female recruits, similarly to a disparity demonstrated in female athletes.

METHODS

A literature review of articles relevant to our review was conducted using PubMed, utilizing keywords stress fracture, military, recruits, diagnosis, management, treatment, prevention, epidemiology, background, and/or female. Articles older than 10 years old (prior to 2010) were not considered. Review articles were considered, but if a research article was cited by a review, the research was included directly. Articles with primary military data, members of the military as subjects, especially when female recruits were included, were strongly considered for inclusion in this review.

RESULTS

SFx can cause medical morbidity and financial burden and can require discharge from military service. SFx management in the military has cost the United States approximately $100 million annually, which may be underestimated due to lost duty hours or medical discharge with resulting compensation. However, SFx incidence rates have been demonstrated to be reducible with concerted efforts in military cohorts.

CONCLUSION

This review, Part I of a two-part series, provides updated information for multidisciplinary management of SFx in female military recruits. There are many similarities to management in athletes, but unique nuances of the military recruit require specific knowledge to reduce the high incidence rates of injury.

Associations between red blood cell indices and iron status and neurocognitive function in young adults: Evidence from memory and executive function tests and event-related potentials

Cognitive impairment has been associated with anemia and iron deficiency; however, brain electrophysiological studies correlating red blood cell (RBC) indices and iron status to cognition in adulthood are scarce. We aimed to assess neurocognitive function in young adults of the general population and its correlation with RBC indices and iron status. Neurocognitive function was investigated using scalp-recorded event-related potentials (ERPs) within the context of a task-switching paradigm. ERPs and test performance were also compared across groups of "high"/"low" RBC and iron indices. Working memory was examined using the digit span test, in which mean corpuscular hemoglobin (MCH), mean corpuscular volume (MCV), and ferritin were found to be significant predictors of test performance, with higher MCH/MCV/ferritin being associated with better test scores. In the switching task, MCH, MCV, and ferritin were found to be significant predictors of task performance, with higher MCH/MCV/ferritin levels associated with a lower percentage of errors. Electrophysiological results showed that MCH and MCV were significant predictors of ERPs amplitude, with lower MCH/MCV levels associated with greater amplitude, which may reflect compensatory processes. P1, N1, P2, and P3 were greater for the low MCH/MCV groups. This is the first evidence of association between levels of MCH/MCV and brain function while engaged in an executive function task; possibly reflecting brain iron availability.

Reducing infantile anemia: insight on patterns of process and outcome indicators by ethnicity and socioeconomic class during a 10-year intervention program and 5 years after

Background

In 2005, Clalit Health Services (CHS), the largest health maintenance organization in Israel, initiated an intervention program aimed at reducing the prevalence rate of infantile anemia (IA). This study evaluated the progress made during the intervention (2005–2014) and its yield 5 years after it ended (2019).

Methods

The CHS database was retrospectively reviewed twice yearly from 2005 to 2014 for repetitive samples of children aged 9 to 18 months regarding the previous half-year interval, and a single sample in 2019. Data were collected on gender, ethnicity (Jewish/non-Jewish), socioeconomic class (SEC; low/intermediate/high), hemoglobin testing (yes/no), and hemoglobin level (if tested). Excluded were infants with documented or suspected hemoglobinopathy.

Results

At study initiation, the rate of performance of hemoglobin testing was 54.7%, and the IA prevalence rate was 7.8%. The performance rate was lower in the Jewish than the non-Jewish subpopulation. The low-SEC subpopulation had a similar hemoglobin testing rate to the high-SEC subpopulation but double the IA prevalence rate. Overall, by the end of the intervention (2014), the performance rate increased to 87.5%, and the AI prevalence rate decreased to 3.4%. In 2019, there was little change in the performance rate from the end of the intervention (88%) and the IA prevalence was further reduced to 2.7%. The non-Jewish and low-SEC subpopulations showed the most improvement which was maintained and even bettered 5 years after the intervention ended.

Conclusions

The 10-year IA intervention program introduced by CHS in 2005 led to a reduction in IA prevalence rate to about 3.5% in all sub-populations evaluated. By program end, the results in the weaker subpopulations, which had the highest prevalence of IA at baseline, were not inferior to those in the stronger subpopulations. We recommended to the Israel Ministry of Health to adopt the intervention countrywide, and we challenge other countries to consider similar interventions.

Feeding female soldiers: Consideration of sex-specific nutrition recommendations to optimise the health and performance of military personnel

Appropriate nutrition recommendations are required to optimise the health and performance of military personnel, yet limited data are available on whether male and female military personnel have different nutrition requirements.

OBJECTIVES

To consider the evidence for sex-specific nutrition requirements to optimise the health and performance of military personnel.

DESIGN

Narrative review.

METHODS

Published literature was reviewed, with a focus on sex-specific requirements, in the following areas: nutrition for optimising muscle mass and function, nutrition during energy deficit, and nutrition for reproductive and bone health.

RESULTS

There are limited data on sex differences in protein requirements but extant data suggest that, despite less muscle mass, on average, in women, sex-specific protein feeding strategies are not required to optimise muscle mass in military-aged individuals. Similarly, despite sex differences in metabolic and endocrine responses to energy deficit, current data do not suggest a requirement for sex-specific feeding strategies during energy deficit. Energy deficit impairs health and performance, most notably bone and reproductive health and these impairments are greater for women. Vitamin D, iron and calcium are important nutrients to protect the bone health of female military personnel due to increased risk of stress fracture.

CONCLUSIONS

Women have an increased incidence of bone injuries, less muscle mass and are more susceptible to the negative effects of energy deficit, including compromised reproductive health. However, there are limited data on sex differences in response to various nutrition strategies designed to improve these elements of health and performance. Future studies should evaluate whether sex-specific feeding recommendations are required.

Musculoskeletal Injuries Among Females in the Military: A Scoping Review

INTRODUCTION

Musculoskeletal injuries (MSKi) are a common challenge for those in military careers. Compared to their male peers, reports indicate that female military members and recruits are at greater risk of suffering MSKi during training and deployment. The objectives of this study were to identify the types and causes of MSKi among female military personnel and to explore the various risk factors associated with MSKi.

MATERIALS AND METHODS

A scoping review was conducted over a 4-month time frame of English language, peer-reviewed studies published from 1946 to 2019. Search strategies for major biomedical databases (e.g., MEDLINE; Embase Classic + Embase; and the following EBM Reviews-Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects, Health Technology Assessment, and the NHS Economic Evaluation Database) were developed by a senior medical information specialist and included 2,891 titles/abstracts. Study selection and data collection were designed according to the Population, Concept, and Context framework. Studies were included if the study population provided stratified data for females in a military context.

RESULTS

From a total of 2,287 citations captured from the literature searches, 168 peer-reviewed publications (144 unique studies) were eligible for inclusion. Studies were identified from across 10 countries and published between 1977 and 2019. Study designs were primarily prospective and retrospective cohorts. Most studies assessed both prevalence/incidence and risk factors for MSKi (62.50%), with few studies assessing cause (13.69%). For MSKi of female recruits compared to active female members, the prevalence was higher (19.7%-58.3% vs. 5.5%-56.6%), but the incidence (0.02%-57.7% vs. 13.5%-71.9%) was lower. The incidence of stress fractures was found to be much higher in female recruits than in active members (1.6%-23.9% vs. 2.7%). For anthropometric risk factors, increased body fat was a predictor of MSKi, but not stress fractures. For physiological risk factors for both female military groups, being less physically fit, later menarche, and having no/irregular menses were predictors of MSKi and stress fractures. For biomechanical risk factors, among female recruits, longer tibial length and femoral neck diameter increased the risk of stress fractures, and low foot arch increased risk of an ankle sprain. For female active military members, differences in shoulder rotation and bone strength were associated with risk of MSKi. For biological sex, being female compared to male was associated with an increased risk of MSKi, stress fractures, and general injuries. The consequences of experiencing MSKi for active military included limited duties, time off, and discharge. For recruits, these included missed training days, limited duty days, and release.

CONCLUSIONS

This scoping review provides insight into the current state of the evidence regarding the types and causes of MSKi, as well as the factors that influence MSKi among females in the military. Future research endeavors should focus on randomized controlled trials examining training paradigms to see if women are more susceptible. The data presented in the scoping review could potentially be used to develop training strategies to mitigate some of the identified barriers that negatively impact women from pursuing careers in the military.

Religious dietary rules and their potential nutritional and health consequences

BACKGROUND

The vast majority of the world population declares affiliation to a religion, predominantly Christianity and Islam. Many religions have special dietary rules, which may be more or less strictly adhered to.

METHODS

Religious food rules were collected from holy books and religious websites as well as their translation into dietary practices. The literature was searched for potential associations between these rules and potential nutritional consequences.

RESULTS

Jewish, Islamic and Indian religions support prolonged breastfeeding. Religious avoidance of alcohol is probably beneficial to health. When strictly applied, a few rules may lead to nutritional inadequacies, mainly in populations living in unfavourable socio-economic or environmental conditions. In Jewish and Muslim observants, animal slaughtering procedures may increase the risk of iron deficiency. Jews may be at risk of excess sodium intake related to home-prepared foods. A vegan diet, as observed by some believers, often by drifting from original precepts, or by some Hindus or Buddhists, may result in vitamin B12, calcium, iron, zinc, selenium and n-3 fatty acids deficiencies.

CONCLUSION

When implemented in accordance with the rules, most religious food precepts are not detrimental to health, as suggested by the fact that they have more or less been followed for millennia. Nevertheless, some practices may lead to nutritional inadequacies, such as iron, calcium, vitamin D and vitamin B12 deficiencies. Patients with low socio-economic status, children and women of childbearing age are of particular risk of such deficiencies. Being aware of them should help health professionals to take an individualized approach to decide whether to supplement or not.

Training Load Capacity, Cumulative Risk, and Bone Stress Injuries: A Narrative Review of a Holistic Approach

Bone stress injuries (BSIs) are a common orthopedic injury with short-term, and potentially long-term, effects. Training load capacity, influenced by risk factors, plays a critical role in the occurrence of BSIs. Many factors determine how one's body responds to repetitive loads that have the potential to increase the risk of a BSI. As a scientific community, we have identified numerous isolated BSI risk factors. However, we have not adequately analyzed the integrative, holistic, and cumulative nature of the risk factors, which is essential to determine an individual's specific capacity. In this narrative review, we advocate for a personalized approach to monitor training load so that individuals can optimize their health and performance. We define “cumulative risk profile” as a subjective clinical determination of the number of risk factors with thoughtful consideration of their interaction and propose that athletes have their own cumulative risk profile that influences their capacity to withstand specific training loads. In our narrative review, we outline BSI risk factors, discuss the relationship between BSIs and training load, highlight the importance of individualizing training load, and emphasize the use of a holistic assessment as a training load guide.

Long-Term Accumulation of Metals in the Skeleton as Related to Osteoporotic Derangements

The concentrations of metals in the environment are still not within the recommended limits as set by the regulatory authorities in various countries because of human activities. They can enter the food chain and bioaccumulate in soft and hard tissues/organs, often with a long half-life of the metal in the body. Metal exposure has a negative impact on bone health and may result in osteoporosis and increased fracture risk depending on concentration and duration of metal exposure and metal species. Bones are a long-term repository for lead and some other metals, and may approximately contain 90% of the total body burden in birds and mammals. The present review focuses on the most common metals found in contaminated areas (mercury, cadmium, lead, nickel, chromium, iron, and aluminum) and their effects on bone tissue, considering the possibility of the long-term bone accumulation, and also some differences that might exist between different age groups in the whole population.

Sex-Specific Changes in Physical Performance Following Military Training: A Systematic Review

INTRODUCTION

Men and women joining the military undergo the same training, often in mixed-sex platoons. Given the inherent physiological and physical performance differences between men and women, it is reasonable to question whether sex differences exist in the adaptation to military training and, therefore, whether sex-specific training should be employed to optimise training adaptations.

OBJECTIVE

To systematically review the literature evaluating changes in the physical performance of men and women following military training.

METHODS

Six database sources were searched in addition to extensive secondary searching. Primary prospective intervention studies (all designs) evaluating physical training interventions in military populations, reporting pre- to post-training changes in physical fitness outcomes for both women and men, were included.

RESULTS

We screened 3966 unique records. Twenty-nine studies (n = 37 study reports) were included, most of which were conducted in the USA and evaluated initial training for military recruits. Positive changes were more consistently observed in aerobic fitness and muscle strength (whole body and upper body) outcomes than lower body strength, muscle power or muscle endurance outcomes, following physical training. Relative pre- to post-training changes for all outcome measures tended to be greater in women than men although few statistically significant sex by outcome/time interactions were observed.

CONCLUSION

Improvements in some, but not all, performance components were observed following a period of military training. Largely, these improvements were not significantly different between sexes. Further prospective research is needed to evaluate sex-specific differences in the response to physical training in controlled conditions to improve military physical training outcomes for both sexes.

Musculoskeletal Injuries Among Female Soldiers Working With Dogs

INTRODUCTION

Female soldiers serving in the Israeli Defense Forces canine unit may be at increased risk of overuse injuries related to working with military dogs. We hypothesized that this particular type of occupational exposure may lead to an increased strain of the upper extremity due to such non-physiologic motions as pulling the dog's strap or resisting the sudden pulling by the dog, and may result in an increased rate of overuse injuries.

MATERIALS AND METHODS

We compared incidence of overuse injuries in a retrospective cohort of female soldiers who served either in the military working dogs' unit (MWD), or in the light infantry battalions (Infantry) from 2005 to 2015. We compared injury incidence of both groups during two periods: 5 mo of basic training (neither worked with dogs) and 19 or more months of combat service. Incidence was calculated as number of diagnoses per person-months (rate ratios, RR); each diagnosis counted once per study subject. We used RR confidence intervals to compare incidence of injuries between groups.

RESULTS

There were 3,443 person-months in the MWD group and 194,590 person-months in the Infantry group. There was no difference in injury incidence between groups during the initial period of basic training. During the second period, MWDs had higher incidence of upper limb (RR = 1.45, p = 0.048) and hip (RR = 3.6, p < 0.0001) injuries. The association between service with dogs and upper limb injuries remained significant (RR = 1.09, p = 0.005) after adjusting for confounding variables in the multivariate regression analysis. Other independent predictors of the upper limb overuse injuries included each additional month of service (RR = 1.003, p = 0.008), Eastern European origin compared with Israeli-born recruits (RR = 0.97, p = 0.03), increased body weight in increments of 10 kg (RR = 1.008, p = 0.03), anemia (RR = 1.02, p = 0.02) and fatigue (RR = 1.05, p ≤ 0.0001).

CONCLUSIONS

We found that service in the MWD unit was associated with increased risk of upper limb injuries. Identification of the exact mechanism of injury and targeted interventions, as well as treatment of anemia and fatigue may lead to reduction of injuries in this unit.

The Effect of Previous Methylphenidate Use on Incidence of Stress Fractures in Military Recruits: A Retrospective Cohort

BACKGROUND

Previous research has detected an increased risk of stress fractures among subjects who reported previous use of methylphenidate. Conversely, stimulant medication use has been associated with traumatic fracture risk reduction, possibly because of the improved control of the underlying symptoms of attention deficit hyperactivity disorder (ADHD). The goal of this study was to investigate the effect of previous methylphenidate use on the incidence of traumatic and stress fractures among combat soldiers with previously treated and untreated ADHD.

METHODS

The retrospective cohort included 100,000 combat soldiers recruited to the Israeli Defense Forces from 2005 through 2015. Diagnosis of ADHD and previous exposure to methylphenidate were determined on the basis of self-reported recruitment questionnaires and medical records. Accordingly, the cohort was divided into 3 groups: subjects with ADHD who were previously treated with methylphenidate (n = 689), untreated subjects with ADHD reporting no medication use (n = 762), and controls having no ADHD diagnosis (n = 98,549). Logistic regressions were fitted to determine the odds ratios (ORs) of study subjects for stress and non-stress (traumatic) fractures. Multivariate analysis incorporated baseline characteristics, including age, sex, weight, duration of service, and diagnosis of anemia, at some point during the service.

RESULTS

After adjustment for sex, anemia, weight, age, and duration of service, the risk of traumatic fractures was increased in both subjects with treated ADHD (OR, 1.03 [95% confidence interval (CI), 1.00 to 1.05]) and subjects with untreated ADHD (OR, 1.04 [95% CI, 1.02 to 1.07]) compared with controls. Subjects in the treated ADHD group were at a higher risk of stress fractures (OR, 1.04 [95% CI, 1.02 to 1.07]). Interestingly, a diagnosis of anemia was an independent predictor of stress fractures (OR, 1.05 [95% CI, 1.04 to 1.06]).

CONCLUSIONS

Methylphenidate use is associated with an increased risk of stress fractures but a decreased risk of traumatic fractures in individuals diagnosed with ADHD. These and previous findings may serve as sufficient basis for screening for other risk factors and perhaps taking prevention measures in all those using stimulant medications, especially those planning to engage in strenuous physical activity.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Iron deficiency beyond erythropoiesis: should we be concerned?

OBJECTIVE

To consider the key implications of iron deficiency for biochemical and physiological functions beyond erythropoiesis.

METHODS

PubMed was searched for relevant journal articles published up to August 2017.

RESULTS

Anemia is the most well-recognized consequence of persisting iron deficiency, but various other unfavorable consequences can develop either before or concurrently with anemia. Mitochondrial function can be profoundly disturbed since iron is a cofactor for heme-containing enzymes and non-heme iron-containing enzymes in the mitochondrial electron transport chain. Biosynthesis of heme and iron-sulfur clusters in the mitochondria is inhibited, disrupting synthesis of compounds such as hemoglobin, myoglobin, cytochromes and nitric oxide synthase. The physiological consequences include fatigue, lethargy, and dyspnea; conversely, iron repletion in iron-deficient individuals has been shown to improve exercise capacity. The myocardium, with its high energy demands, is particularly at risk from the effects of iron deficiency. Randomized trials have found striking improvements in disease severity in anemic but also non-anemic chronic heart failure patients with iron deficiency after iron therapy. In vitro and pre-clinical studies have demonstrated that iron is required by numerous enzymes involved in DNA replication and repair, and for normal cell cycle regulation. Iron is also critical for immune cell growth, proliferation, and differentiation, and for specific cell-mediated effector pathways. Observational studies have shown that iron-deficient individuals have defective immune function, particularly T-cell immunity, but more evidence is required. Pre-clinical models have demonstrated abnormal myelogenesis, brain cell metabolism, neurotransmission, and hippocampal formation in iron-deficient neonates and young animals. In humans, iron deficiency anemia is associated with poorer cognitive and motor skills. However, the impact of iron deficiency without anemia is less clear.

CONCLUSION

The widespread cellular and physiological effects of iron deficiency highlight the need for early detection and treatment of iron deficiency, both to ameliorate these non-erythropoietic effects, and to avoid progression to iron deficiency anemia.

Low serum iron is associated with high serum intact FGF23 in elderly men: The Swedish MrOS study

BACKGROUND

Fibroblast growth factor (FGF23) is a protein that is produced by osteoblasts and osteocytes. Increased serum levels of FGF23 have been associated with increased risks of osteoporotic fractures and cardiovascular disease, particularly in participants with poor renal function. Serum iron (Fe) has been suggested as a regulator of FGF23 homeostasis.

OBJECTIVE

To determine whether Fe and iron status are determinants of the levels of intact FGF23 (iFGF23) in elderly men.

METHODS

The MrOS study is a population-based study of elderly men (N=1010; mean age, 75.3years; range, 69-81years). The levels of Fe, transferrin saturation (TS), and ferritin were evaluated in relation to the serum concentrations of iFGF23 before and after adjustments for confounders.

RESULTS

TS <15% was found in 3.5% (34/977) of the participants, who had a higher median level iFGF23 compared with the remaining subjects (47.4μmol/L vs. 41.9μmol/L, p=0.008). The levels of iFGF23 correlated negatively (un-adjusted) with the levels of Fe (r=-0.17, p<0.001), TS (r=-0.16, p<0.001) and serum ferritin (r=-0.07, p=0.022). In addition, in participants with estimated glomerular filtration rate eGFRCystatin C>60mL/min, the levels of iFGF23 correlated (age-adjusted) negatively with the levels of Fe (r=-0.15, p<0.001) and TS (r=-0.17, p<0.001). The level of iFGF23 correlated positively (un-adjusted) with lumbar spine bone mineral density (BMD) (r=0.14, p<0.001), total body BMD (r=0.11, p=0.001), and total hip BMD (r=0.09, p=0.004). The corresponding correlations, when adjusted for age, weight, and height were: r=0.08, p=0.018; r=0.05, p=0.120; and r=0.02, p=0.624, respectively. No associations were found between BMD and the levels of Fe or TS. Multiple step-wise linear regression analyses [adjusting for age, body mass index (BMI), comorbidity index, cystatin C, C-reactive protein (hs-CRP), serum vitamin D 25-OH (25OHD), phosphate, calcium, parathyroid hormone (PTH), erythropoietin, hemoglobin, lumbar spine BMD, apolipoprotein B/A1 ratio] were performed in three separate models with Fe, TS or ferritin as potential explanatory variables. Fe and TS, but not ferritin, were independent predictors of iFGF23 level (standardized β-values: -0.10, p<0.001; -0.10, p<0.001; and -0.05, p=0.062, respectively).

CONCLUSION

Low levels of Fe in elderly men are associated with high levels of iFGF23, independently of markers of inflammation and renal function, suggesting an iron-related pathway for FGF23 regulation.

Copper, iron, and selenium dietary deficiencies negatively impact skeletal integrity: A review

Nutrients have been known to have a significant role in maintaining the health of the skeleton, both bone and cartilage. The nutrients that have received the majority of the attention are Vitamin D and calcium. However, limited attention has been directed toward three trace elements that may have mechanistic impact upon the skeletal tissues and could compromise skeletal health resulting from inadequate intakes of copper, iron, and selenium. The role of copper and selenium has been known, but the role of iron has only received recent attention. Copper deficiency is thought to impact bone health by a decrease in lysyl oxidase, a copper-containing enzyme, which facilitates collagen fibril crosslinking. Iron deficiency impact upon bone has only recently been discovered but the exact mechanism on how the deficient states enhance bone pathology is speculative. Selenium deficiency has an impact on cartilage thereby having an indirect impact on bone. However, several studies suggest that a mycotoxin when consumed by humans is the culprit in some cartilage disorders and the presence of selenium could attenuate the pathology. This review summarizes the current knowledge base with respect to skeletal integrity when each of these three trace elements are inadequate in diets of both animals and humans.