Vitamin D and Stress Fractures in Sport: Preventive and Therapeutic Measures-A Narrative Review.

There are numerous risk factors for stress fractures that have been identified in literature. Among different risk factors, a prolonged lack of vitamin D (25(OH)D) can lead to stress fractures in athletes since 25(OH)D insufficiency is associated with an increased incidence of a fracture. A 25(OH)D value of <75.8 nmol/L is a risk factor for a stress fracture. 25(OH)D deficiency is, however, only one of several potential risk factors. Well-documented risk factors for a stress fracture include female sex, white ethnicity, older age, taller stature, lower aerobic fitness, prior physical inactivity, greater amounts of current physical training, thinner bones, 25(OH)D deficiency, iron deficiency, menstrual disturbances, and inadequate intake of 25(OH)D and/or calcium. Stress fractures are not uncommon in athletes and affect around 20% of all competitors. Most athletes with a stress fracture are under 25 years of age. Stress fractures can affect every sporty person, from weekend athletes to top athletes. Stress fractures are common in certain sports disciplines such as basketball, baseball, athletics, rowing, soccer, aerobics, and classical ballet. The lower extremity is increasingly affected for stress fractures with the locations of the tibia, metatarsalia and pelvis. Regarding prevention and therapy, 25(OH)D seems to play an important role. Athletes should have an evaluation of 25(OH)D -dependent calcium homeostasis based on laboratory tests of 25-OH-D3, calcium, creatinine, and parathyroid hormone. In case of a deficiency of 25(OH)D, normal blood levels of ≥30 ng/mL may be restored by optimizing the athlete's lifestyle and, if appropriate, an oral substitution of 25(OH)D. Very recent studies suggested that the prevalence of stress fractures decreased when athletes are supplemented daily with 800 IU 25(OH)D and 2000 mg calcium. Recommendations of daily 25(OH)D intake may go up to 2000 IU of 25(OH)D per day.

Low serum 25-hydroxyvitamin D status in the pathogenesis of stress fractures in military personnel: An evidenced link to support injury risk management.

Stress fractures are common amongst healthy military recruits and athletes. Reduced vitamin D availability, measured by serum 25-hydroxyvitamin D (25OHD) status, has been associated with stress fracture risk during the 32-week Royal Marines (RM) training programme. A gene-environment interaction study was undertaken to explore this relationship to inform specific injury risk mitigation strategies. Fifty-one males who developed a stress fracture during RM training (n = 9 in weeks 1-15; n = 42 in weeks 16-32) and 141 uninjured controls were genotyped for the vitamin D receptor (VDR) FokI polymorphism. Serum 25OHD was measured at the start, middle and end (weeks 1, 15 and 32) of training. Serum 25OHD concentration increased in controls between weeks 1-15 (61.8±29.1 to 72.6±28.8 nmol/L, p = 0.01). Recruits who fractured did not show this rise and had lower week-15 25OHD concentration (p = 0.01). Higher week-15 25OHD concentration was associated with reduced stress fracture risk (adjusted OR 0.55[0.32-0.96] per 1SD increase, p = 0.04): the greater the increase in 25OHD, the greater the protective effect (p = 0.01). The f-allele was over-represented in fracture cases compared with controls (p<0.05). Baseline 25OHD status interacted with VDR genotype: a higher level was associated with reduced fracture risk in f-allele carriers (adjusted OR 0.39[0.17-0.91], p = 0.01). Improved 25OHD status between weeks 1-15 had a greater protective effect in FF genotype individuals (adjusted OR 0.31[0.12-0.81] vs. 1.78[0.90-3.49], p<0.01). Stress fracture risk in RM recruits is impacted by the interaction of VDR genotype with vitamin D status. This further supports the role of low serum vitamin D concentrations in causing stress fractures, and hence prophylactic vitamin D supplementation as an injury risk mitigation strategy.

Vitamin D Supplementation in Military Personnel: A Systematic Review of Randomized Controlled Trials.

CONTEXT: Vitamin D supplementation is important in military research because of its role in musculoskeletal health. OBJECTIVE: This systematic review examined the effects of vitamin D supplementation on serum 25-hydroxyvitamin D (25(OH)D) concentrations and musculoskeletal health outcomes in military personnel. DATA SOURCES: A comprehensive search was conducted using MEDLINE, EMBASE, CINAHL, SportDiscus, and the Cochrane Library databases and the reference lists of existing review articles and relevant studies. STUDY SELECTION: Reviewers independently screened titles, abstracts, and full texts of the articles using predefined criteria. STUDY DESIGN: Systematic review of randomized controlled trials (RCTs) using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement. LEVEL OF EVIDENCE: Level 3. DATA EXTRACTION: Three reviewers independently extracted data and assessed the methodological quality. Mean differences with 95% CI in serum 25(OH)D concentrations between the vitamin D and placebo arms were calculated. RESULTS: Four RCTs were included in the qualitative analyses. The 25(OH)D concentrations were improved with 2000 IU/d supplementation (mean difference, 3.90 ng/mL; 95% CI, 0.22-7.58). A trial on female Navy recruits showed a significant decrease in stress fractures (risk ratio, 0.77; 95% CI, 0.62-0.95), particularly tibial fractures, from daily supplementation of 800 IU vitamin D and 2000 mg calcium. CONCLUSION: There was a positive trend in 25(OH)D concentrations from higher doses of supplementary vitamin D in military submariners and a possible benefit to bone health when vitamin D was combined with calcium.

Nutrition for the Prevention and Treatment of Injuries in Track and Field Athletes.

Injuries are an inevitable consequence of athletic performance with most athletes sustaining one or more during their athletic careers. As many as one in 12 athletes incur an injury during international competitions, many of which result in time lost from training and competition. Injuries to skeletal muscle account for over 40% of all injuries, with the lower leg being the predominant site of injury. Other common injuries include fractures, especially stress fractures in athletes with low energy availability, and injuries to tendons and ligaments, especially those involved in high-impact sports, such as jumping. Given the high prevalence of injury, it is not surprising that there has been a great deal of interest in factors that may reduce the risk of injury, or decrease the recovery time if an injury should occur: One of the main variables explored is nutrition. This review investigates the evidence around various nutrition strategies, including macro- and micronutrients, as well as total energy intake, to reduce the risk of injury and improve recovery time, focusing upon injuries to skeletal muscle, bone, tendons, and ligaments.

Pharmacological interventions for the prevention of insufficiency fractures and avascular necrosis associated with pelvic radiotherapy in adults.

BACKGROUND: Pelvic radiotherapy is a treatment delivered to an estimated 150,000 to 300,000 people annually across high-income countries. Fractures due to normal stresses on weakened bone due to radiotherapy are termed insufficiency fractures. Pelvic radiotherapy-related interruption of the blood supply to the hip is termed avascular necrosis and is another recognised complication. The reported incidences of insufficiency fractures are 2.7% to 89% and risk of developing avascular necrosis is 0.5%. These complications lead to significant morbidity in terms of pain, immobility and consequently risk of infections, pressure sores and mortality. OBJECTIVES: To assess the effects of pharmacological interventions for preventing insufficiency fractures and avascular necrosis in adults over 18 years of age undergoing pelvic radiotherapy. SEARCH METHODS: We performed electronic literature searches in the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase and DARE to 19 April 2017. We also searched trial registries. Further relevant studies were identified through handsearching of citation lists of included studies. SELECTION CRITERIA: Randomised controlled trials (RCTs) or non RCTs with concurrent comparison groups including quasi-RCTs, cluster RCTs, prospective cohort studies and case series of 30 or more participants were screened. We included studies assessing the effect of pharmacological interventions in adults over 18 years of age undergoing radical pelvic radiotherapy as part of anticancer treatment for a primary pelvic malignancy. We excluded studies involving radiotherapy for bone metastases. We assessed use of pharmacological interventions at any stage before or during pelvic radiotherapy. Interventions included calcium or vitamin D (or both) supplementation, bisphosphonates, selective oestrogen receptor modulators, hormone replacement therapy (oestrogen or testosterone), denosumab and calcitonin. DATA COLLECTION AND ANALYSIS: Two review authors independently assessed trial quality and extracted data. We contacted study authors to obtain missing data. Data were to be pooled using the random-effects model if study comparisons were similar, otherwise results were to be reported narratively. MAIN RESULTS: We included two RCTs (1167 participants). The first RCT compared zoledronic acid with placebo in 96 men undergoing pelvic radiotherapy for non-metastatic prostate cancer.The second RCT had four treatment arms, two of which evaluated zoledronic acid plus adjuvant androgen suppression compared with androgen suppression only in 1071 men undergoing pelvic radiotherapy for non-metastatic prostate cancer.Both studies were at a moderate to high risk of bias and all evidence was judged to be of very low certainty.The studies provided no evidence on the primary outcomes of the review and provided limited data in relation to secondary outcomes, such that meta-analyses were not possible. Both studies focused on interventions to improve bone health in relation to androgen deprivation rather than radiation-related insufficiency fractures and avascular necrosis. Few fractures were described in each study and those described were not specific to insufficiency fractures secondary to radiotherapy. Both studies reported that zoledronic acid in addition to androgen deprivation and pelvic radiotherapy led to improvements in BMD; however, the changes in BMD were measured and reported differently. There was no available evidence regarding adverse effects. AUTHORS' CONCLUSIONS: The evidence relating to interventions to prevent insufficiency fractures and avascular necrosis associated with pelvic radiotherapy in adults is of very low certainty. This review highlights the need for prospective clinical trials using interventions prior to and during radiotherapy to prevent radiation-related bone morbidity, insufficiency fractures and avascular necrosis. Future trials could involve prospective assessment of bone health including BMD and bone turnover markers prior to pelvic radiotherapy. The interventions for investigation could begin as radiotherapy commences and remain ongoing for 12 to 24 months. Bone turnover markers and BMD could be used as surrogate markers for bone health in addition to radiographic imaging to report on presence of insufficiency fractures and development of avascular necrosis. Clinical assessments and patient reported outcomes would help to identify any associated adverse effects of treatment and quality of life outcomes.

Establishing a hospital based fracture liaison service to prevent secondary insufficiency fractures.

In the aging population worldwide, osteoporosis is a relatively common condition and a major cause of long-term morbidity. Initial fragility fractures can lead to subsequent fractures. After a vertebral fracture, the risk of any another fracture increases 200% and that of a subsequent hip fracture increases 300%. For starting a hospital based Fracture Liaison Service (FLS) program, the nucleus is based on a physician champion, a FLS coordinator, and a nurse manager. A Fracture Liaison Service (FLS) is a multidisciplinary system approach to reducing subsequent fracture risk in patients with a recent fragility fracture due to compromised bone health by identifying them at or close to the time when they are treated at the hospital for fracture and providing them with easy access to osteoporosis care. It has been shown that when compared to other models such as referral letters to primary care physicians or endocrinologists, the FLS model results in a higher rate of diagnosis and treatment with less attrition in the posffracture phase. Insufficiency fracture care requires more than surgery to stabilize a fractured bone. The FLS program provides an opportunity to treat osteoporosis from a public health perspective rather than leaving this to the whims of individual physicians. This is achieved by providing a seamless integration of care by health care providers, nursing staff and administration. The FLS can be adapted to any model of care including academic health systems. FLS provides a holistic approach to identify patients as well as to provide evidence-based interventions to prevent subsequent fractures. The long term goal is that internationally FLS will result in in decreased fracture-related morbidity, mortality and overall health care expenditure.

Medication management after intramedullary nailing of atypical fractures.

Long term use of bisphosphonates (BPs) in osteoporotic patients may be associated with stress fractures of the sub-trochanteric and shaft area of the femur, so called "atypical" femoral fractures (AFF). Specific diagnosis criteria have been defined with 5 major features; the presence of four of them characterizes the AFF. Once a complete fracture occurred, the best surgical treatment is closed reduction and intra medullary nailing. The BPs treatment should be stopped immediately after an AFF occurred. Dietary calcium and vitamin D status should be assessed, and adequate supplementation prescribed. Principle of combination of a systematic bone anabolic treatment is strongly debated. The recombinant parathyroid hormone 1-34 or Teriparatide ® (TPTD) has an anabolic effect on bone and prevent osteoporotic fractures. Available preclinical and clinical data have also demonstrated the role played by TPTD to enhance bone fracture healing and the potential beneficial effect in impaired fracture healing or specific clinical condition like AFFs. Some authors have proposed in incomplete BP use stress fractures different medical management according the MRI findings. Bone anabolic agents may be promising both to prevent healing complications in AFFs and to promote healing in conservative treatment of incomplete AFFs. More clinical studies are needed to confirm this hypothesis.

Efecto de distintos protocolos de irrigación en la resistencia a la fractura de dientes tratados endodónticamente / Effect of different irrigation protocols in the fracture resistance of endodontically treated teeth

Introducción: El objetivo del tratamiento endodóntico es la prevención y eliminación de una infección microbiana en el sistema de conductos radiculares gracias a la instrumentación, irrigación y obturación. Como pieza clave del tratamiento, la irrigación se tiene que enfrentar a diversos problemas siendo uno de ellos su posible efecto en la erosión dentinaria. Objetivo: Cuantificar la erosión dentinaria causada por distintas secuencias de irrigación, mediante la resistencia a la fractura. Material y métodos: Se seleccionaron 60 dientes unirradiculares que fueron instrumentados y montados en acrílico autopolimerizable, con espacio que simulaba el ligamento periodontal, y fueron divididos en dos grupos a los que se realizó un protocolo de irrigación con EDTA y NaClO (de 1 y 20 minutos respectivamente) y otro sin irrigación como control. Las muestras fueron posteriormente sometidas a una máquina de ensayos dinámicos de materiales que aplicó fuerza constante hasta fractura. Resultados: La media de la carga de rotura fue similar en los tres grupos, observándose ligeras diferencias del grupo 1 (NaClO 1 minuto) con el resto y mas variabilidad entre las muestras de dicho grupo. Conclusiones: En las condiciones de este estudio, la resistencia del diente no se ve afectada entre irrigar 1 minuto o 20 minutos de NaClO, después de eliminar el barrillo dentinario (AU)

The objectives: in endodontic therapy are prevention and the elimination of a microbial infection in the root canal system. This is done with instrumentation, irrigation and the adequate sealing of the root canals. A key factor in achieving a successful treatment is irrigation; nevertheless, irrigating has potential secondary detrimental effects, such as dentinal erosion. Objective: Quantifying the dentinal erosion in teeth caused by diverse irrigation protocols, and measuring its resistance to fracture. Material and Methods: A selection of 60 teeth with one canal was made. They were instrumented and placed in an acrylic base, and a simulation of the periodontal ligament was created. The teeth were divided in three groups. The first two, followed an irrigation protocol of EDTA and NaClO (1 or 20 minutes, depending on the group), and the third, a control group. The teeth were then subjected to pressure until fracture was achieved. Results: The average load in which the teeth were able to fracture was similar in the groups. However, there were slight differences between group 1 (NaClO, 1 minute), in comparison with the other groups. Conclusions: In this study, we determined that after removing the smear layer, there is no difference (1 or 20 minutes NaClO) in the resistance until fracture (AU)

In-field gait retraining and mobile monitoring to address running biomechanics associated with tibial stress fracture.

We sought to determine if an in-field gait retraining program can reduce excessive impact forces and peak hip adduction without adverse changes in knee joint work during running. Thirty healthy at-risk runners who exhibited high-impact forces were randomized to retraining [21.1 (± 1.9) years, 22.1 (± 10.8) km/week] or control groups [21.0 (± 1.3) years, 23.2 (± 8.7) km/week]. Retrainers were cued, via a wireless accelerometer, to increase preferred step rate by 7.5% during eight training sessions performed in-field. Adherence with the prescribed step rate was assessed via mobile monitoring. Three-dimensional gait analysis was performed at baseline, after retraining, and at 1-month post-retraining. Retrainers increased step rate by 8.6% (P < 0.0001), reducing instantaneous vertical load rate (-17.9%, P = 0.003), average vertical load rate (-18.9%, P < 0.0001), peak hip adduction (2.9° ± 4.2 reduction, P = 0.005), eccentric knee joint work per stance phase (-26.9%, P < 0.0001), and per kilometer of running (-21.1%, P < 0.0001). Alterations in gait were maintained at 30 days. In the absence of any feedback, controls maintained their baseline gait parameters. The majority of retrainers were adherent with the prescribed step rate during in-field runs. Thus, in-field gait retraining, cueing a modest increase in step rate, was effective at reducing impact forces, peak hip adduction and eccentric knee joint work.

Consumption of a calcium and vitamin D-fortified food product does not affect iron status during initial military training: a randomised, double-blind, placebo-controlled trial.

Ca/vitamin D supplementation maintains bone health and decreases stress fracture risk during initial military training (IMT); however, there is evidence that Ca may negatively affect the absorption of other critical micronutrients, particularly Fe. The objective of this randomised, double-blind, placebo-controlled trial was to determine whether providing 2000 mg/d Ca and 25 µg/d vitamin D in a fortified food product during 9 weeks of military training affects Fe status in young adults. Male (n 98) and female (n 54) volunteers enrolled in US Army basic combat training (BCT) were randomised to receive a snack bar with Ca/vitamin D (n 75) or placebo (snack bar without Ca/vitamin D; n 77) and were instructed to consume 2 snack bars/d between meals throughout the training course. Circulating ionised Ca was higher (P0·05) in markers of Fe status between placebo and Ca/vitamin D groups. Collectively, these data indicate that Ca/vitamin D supplementation through the use of a fortified food product consumed between meals does not affect Fe status during IMT.

Six-year follow-up of a characteristic osteolytic lesion in a patient with tumor-induced osteomalacia.

OBJECTIVE: Tumor-induced osteomalacia is a rare paraneoplastic syndrome characterized by hypophosphatemia and inappropriately normal or low 1,25-dihydroxyvitamin D. CLINICAL CASE: Here, we report a 6-year postoperative follow-up of a patient with oncogenic osteomalacia with a distinctive skeletal manifestation. The latter was characterized by an almost linear lytic lesion of a few millimeters with irregular borders, mainly involving the trabecular compartment but extending into cortical shell, located in the middle third of the right fibula. Six years after tumor resection, a sclerotic repair with a complete recovery was observed. Furthermore, we monitored a striking increase in bone mineral density throughout the observation period, reaching a peak of 73% over basal values at lumbar spine after 2 years; at total femur and radius, the peak was 47.5 and 4.6% respectively, after 4 years from tumor resection. CONCLUSIONS: We report for the first time that an osteolytic lesion may be part of the skeletal involvement in tumor-induced osteomalacia.

Preventive osteopathic manipulative treatment and stress fracture incidence among collegiate cross-country athletes.

CONTEXT: Stress fractures are common among athletes, particularly distance runners, with many theories regarding the etiologic process of stress fractures and various studies identifying risk factors or suggesting preventive techniques. To our knowledge, no previous studies have discussed the possible causative effects of somatic dysfunction or the preventive capabilities of osteopathic manipulative treatment (OMT). OBJECTIVE: To apply a preventive OMT protocol for cross-country athletes to reduce the incidence of stress fractures. DESIGN: Cohort study. METHODS: Examinations of cross-country athletes at an NCAA (National Collegiate Athletic Association) Division I university were performed by supervising physician-examiners and first- and second-year osteopathic medical students during several consecutive academic years. Athletes re-enrolled in the study each year they continued to be eligible. The intervention included osteopathic structural examination and OMT that focused on somatic dysfunction identified in the pelvis, sacrum, and lower extremities. RESULTS: More than 1800 participant examinations were performed on 124 male and female participants by 3 supervising physician-examiners and 141 osteopathic medical students over the course of 5 consecutive academic years (2004-2005 to 2008-2009). Data from these academic years were compared with data from the previous 8 academic years (1996-1997 to 2003-2004). An average of 20 new participants enrolled yearly. The number of annual stress fractures per team ranged from 0 to 6 for male participants and 1 to 6 for female participants. The cumulative annual incidence of stress fractures for male participants demonstrated a statistically significant decrease from 13.9% (20 of 144) before intervention to 1.0% (1 of 105) after intervention, resulting in a 98.7% relative reduction in stress-fracture diagnosis (P=.019). The cumulative annual incidence for female participants showed a minimal decrease from 12.9% (23 of 178) before intervention to 12.0% (17 of 142) after intervention, an 8.5% relative reduction in stress-fracture diagnosis (P=.671). The cumulative annual incidence of all participants decreased from 13.4% (43 of 322) before intervention to 7.3% (18 of 247) after intervention, a 45% relative reduction in stress-fracture diagnosis (P=.156). CONCLUSION: There was a statistically significant decrease in the cumulative annual incidence of stress fractures in male, but not female, cross-country athletes after receiving OMT.

Complementary and alternative treatments in sports medicine.

Many patients suffering from pain and dysfunction attributable to musculoskeletal conditions will use some form of complementary and alternative medicine (CAM). Unfortunately, there is a paucity of both the quantity and quality of CAM treatments for specific musculoskeletal conditions. Many CAM treatments are used for a variety of musculoskeletal conditions, but may be more commonly used for specific conditions. This article addresses the use of CAM for specific musculoskeletal conditions, followed by a review of other CAM treatments and their potential indications for a multitude of conditions, based on the current medical literature and traditional use.

Current concept review: vitamin D and stress fractures.

Critical review of the available evidence indicates that a relationship exists between sufficient vitamin D status and stress fractures, although genetic and environmental factors are involved as well. Patients at high risk for stress fracture should be educated on protective training techniques and the potential benefits of supplementation with combined calcium and vitamin D, particularly if increased exercise is planned during winter or spring months, when vitamin D stores are at their lowest. The amount of vitamin D intake required is highly variable depending on many factors including sun exposure, and therefore many recommendations have been made for daily vitamin D intake requirements. While the Institute of Medicine guidelines suggest that 600 to 800 IU of vitamin D are required for adequate bone health in most adults, we recommend that most patients receive 800 to 1,000 IU and perhaps as high as 2,000 IU of vitamin D3 as outlined by the previously mentioned review article since vitamin D is a safe treatment with a high therapeutic index. Also, at least 1,000 mg of calcium per day is required for optimal bone health and 1,200 mg may be needed in certain populations. Orthopaedists should consider prescribing vitamin D and calcium prophylactically in high-risk patients. In patients in whom deficiency is a concern, serum 25(OH)D level is the appropriate screening test, with therapeutic goals for bone health being at least 50 nmol/L (20 ng/mL) and may be as high as 90 to 100 nmol/L (36 to 40 ng/mL).

A review of vitamin D and its effects on athletes.

Research into vitamin D has revealed the important role it plays in a variety of biologic functions. Despite this importance, vitamin D deficiency remains one of the most underdiagnosed conditions in the world. Although no evidence exists that athletes have a higher daily requirement than the general population, vitamin D deficiency in athletic individuals has been linked to decreased physical performance and a predisposition to stress fractures. Research investigating ergogenic effects of direct vitamin D supplementation in non-deficient athletes has yet to be performed. This review discusses the current evidence on the effects of vitamin D in athletes, along with recommended strategies for the correction of deficient states.

Rib stress fractures among rowers: definition, epidemiology, mechanisms, risk factors and effectiveness of injury prevention strategies.

Rib stress fractures (RSFs) can have serious effects on rowing training and performance and accordingly represent an important topic for sports medicine practitioners. Therefore, the aim of this review is to outline the definition, epidemiology, mechanisms, intrinsic and extrinsic risk factors, injury management and injury prevention strategies for RSF in rowers. To this end, nine relevant books, 140 journal articles, the proceedings of five conferences and two unpublished presentations were reviewed after searches of electronic databases using the keywords 'rowing', 'rib', 'stress fracture', 'injury', 'mechanics' and 'kinetics'. The review showed that RSF is an incomplete fracture occurring from an imbalance between the rate of bone resorption and the rate of bone formation. RSF occurs in 8.1-16.4% of elite rowers, 2% of university rowers and 1% of junior elite rowers. Approximately 86% of rowing RSF cases with known locations occur in ribs four to eight, mostly along the anterolateral/lateral rib cage. Elite rowers are more likely to experience RSF than nonelite rowers. Injury occurrence is equal among sweep rowers and scullers, but the regional location of the injury differs. The mechanism of injury is multifactorial with numerous intrinsic and extrinsic risk factors contributing. Posterior-directed resultant forces arising from the forward directed force vector through the arms to the oar handle in combination with the force vector induced by the scapula retractors during mid-drive, or repetitive stress from the external obliques and rectus abdominis in the 'finish' position, may be responsible for RSF. Joint hypomobility, vertebral malalignment or low bone mineral density may be associated with RSF. Case studies have shown increased risk associated with amenorrhoea, low bone density or poor technique, in combination with increases in training volume. Training volume alone may have less effect on injury than other factors. Large differences in seat and handle velocity, sequential movement patterns, higher elbow-flexion to knee-extension strength ratios, higher seat-to-handle velocity during the initial drive, or higher shoulder angle excursion may result in RSF. Gearing may indirectly affect rib loading. Increased risk may be due to low calcium, low vitamin D, eating disorders, low testosterone or use of depot medroxyprogesterone injections. Injury management involves 1-2 weeks cessation of rowing with analgesic modalities followed by a slow return to rowing with low-impact intensity and modified pain-free training. Some evidence shows injury prevention strategies should focus on strengthening the serratus anterior, strengthening leg extensors, stretching the lumbar spine, increasing hip joint flexibility, reducing excessive protraction, training with ergometers on slides or floating-head ergometers, and calcium and vitamin D supplementation. Future research should focus on the epidemiology of RSF over 4-year Olympic cycles in elite rowers, the aetiology of the condition, and the effectiveness of RSF prevention strategies for injury incidence and performance in rowing.

Stress fractures: diagnosis, treatment, and prevention.

Stress fractures are common injuries in athletes and military recruits. These injuries occur more commonly in lower extremities than in upper extremities. Stress fractures should be considered in patients who present with tenderness or edema after a recent increase in activity or repeated activity with limited rest. The differential diagnosis varies based on location, but commonly includes tendinopathy, compartment syndrome, and nerve or artery entrapment syndrome. Medial tibial stress syndrome (shin splints) can be distinguished from tibial stress fractures by diffuse tenderness along the length of the posteromedial tibial shaft and a lack of edema. When stress fracture is suspected, plain radiography should be obtained initially and, if negative, may be repeated after two to three weeks for greater accuracy. If an urgent diagnosis is needed, triple-phase bone scintigraphy or magnetic resonance imaging should be considered. Both modalities have a similar sensitivity, but magnetic resonance imaging has greater specificity. Treatment of stress fractures consists of activity modification, including the use of nonweight-bearing crutches if needed for pain relief. Analgesics are appropriate to relieve pain, and pneumatic bracing can be used to facilitate healing. After the pain is resolved and the examination shows improvement, patients may gradually increase their level of activity. Surgical consultation may be appropriate for patients with stress fractures in high-risk locations, nonunion, or recurrent stress fractures. Prevention of stress fractures has been studied in military personnel, but more research is needed in other populations.

Evaluating the relationship of calcium and vitamin D in the prevention of stress fracture injuries in the young athlete: a review of the literature.

Calcium and vitamin D are recognized as 2 components of nutrition needed to achieve and maintain bone health. Calcium and vitamin D have been clearly shown to improve bone density and prevent fractures at all ages. However, the literature is conflicting as to the role of these nutrients in young athletes ages 18 to 35 years, both for bone development and for the prevention of bone overuse injuries. Differences in findings may relate to study design. Although retrospective and cross-sectional studies have had mixed results, the authors of prospective studies have consistently demonstrated a relationship of increased calcium intake with an improvement in bone density and a decrease in fracture risk. A randomized trial in female military recruits demonstrated that calcium/vitamin D supplementation reduced the incidence of stress fractures. A prospective study in young female runners demonstrated reduced incidence of stress fractures and increased bone mineral density with increased dietary calcium intake. Findings from both studies suggest female athletes and military recruits who consumed greater than 1500 mg of calcium daily exhibited the largest reduction in stress fracture injuries. To date, no prospective studies have been conducted in male athletes or in adolescent athletes. In most studies, males and nonwhite participants were poorly represented. Evidence regarding the relationship of vitamin D intake with the prevention of fractures in athletes is also limited. More prospective studies are needed to evaluate the role of calcium and vitamin D intake in prevention of stress fracture injuries in both male and female adolescent athletes, particularly those participating in sports with greater incidences of stress fracture injury.

Vitamin D: extent of deficiency, effect on muscle function, bone health, performance, and injury prevention.

Vitamin D deficiencyis increasingly being identified in children, adolescents, and adults. Primary production of the active form of vitamin D occurs via a photolytic reaction induced by ultraviolet radiation B. Vitamin D has important effects on bone and muscle as well as on the immune system. Isolation ofa vitamin D receptor on muscle cells has been accompanied by studies showing receptor polymorphisms and age-related functional changeswhich have an effect on muscle performance. Insufficient levels havebeen associated with increased risk of stress fractures, decreased muscle performance, and increased sick days. Although there is still debate about the appropriate levels of vitamin D, studies have suggested a minimal level of 32 ng/ml. Supplementation serves as an inexpensive option associated with reduction in both morbidity and financial costs.

[Bushen Jianpi Huoxue Recipe in prevention and treatment of tibial stress injuries in rabbits].

OBJECTIVE: To explore the effects of Bushen Jianpi Huoxue Recipe, a compound traditional Chinese herbal medicine for tonifying the kidney, invigorating the spleen and promoting blood circulation, on tibial stress injuries in rabbits. METHODS: Thirty-five mature male rabbits were used in the experiment, and randomly divided into 7 groups: sedentary control (SC) group, 1-week exercise (E-1W) group, 2-week exercise (E-2W) group, 3-week exercise (E-3W) group, 4-week exercise (E-4W) group, 3-week exercise and 1-week Chinese herbal medicine treatment (EMT-1W) group, and 4-week exercise and 2-week Chinese herbal medicine treatment (EMT-2W) group. There were 5 rabbits in each group. A rabbit model of tibial stress injuries was established by stimulating the rabbits to jump and run within a high-voltage and low-current electronic cage. Radiologic features, bone scintigraphy, histology and electron microscopy of rabbit tibia were observed, and the content of blood parathyroid hormone (PTH), bone gla protein (BGP) and testosterone was detected by using radioimmunoassay method. RESULTS: After 2-week exercise, changes in histology and osteocytes had a tendency towards stress injuries. Serum PTH and BGP levels were remarkably increased, while serum testosterone level was lower than that in the SC group. Three- and four-week continuous exercise resulted in tibial stress injuries, and the positive changes were observed in X-ray features and radionuclide images. Compared with E-3W group, the levels of serum BGP and testosterone were decreased remarkably. A series of positive results such as prevailing negativeness of X-ray features and radionuclide images, increasing process of osteogenesis, typical osteogenic phase of osteocytes and favorable transformation of biochemical markers was shown in EMT-1W and EMT-2W groups. It also showed remarkable rising levels of serum BGP and testosterone and remarkable reducing level of serum PTH in EMT-1W and EMT-2W groups as compared with E-1W and E-2W groups. CONCLUSION: Bushen Jianpi Huoxue Recipe can prevent and treat exercise-induced tibial stress injuries by stimulating new bone formation and increasing serum testosterone level.