Bone Stress Injuries in Runners

Epidemiology of Bone-Stress Injuries and Health Care Use in Pac-12 Cross-Country Athletes

CONTEXT

Bone-stress injury (BSI) is common in collegiate athletes. Injury rates and health care use in running athletes are not well documented.

OBJECTIVE

To describe the rate and classification of injury and associated health care use in collegiate cross-country runners with BSI.

DESIGN

Descriptive epidemiology study.

SETTING

Sports medicine facilities participating in the Pac-12 Health Analytics Program.

PATIENTS OR OTHER PARTICIPANTS

Pac-12 Conference collegiate cross-country athletes.

MAIN OUTCOME MEASURE(S)

Counts of injury and health care resources used for each injury. Injury rates were calculated based on athlete-seasons.

RESULTS

A total of 168 BSIs were reported over 4 seasons from 80 team-seasons (34 men's and 46 women's team-seasons) and 1220 athlete-seasons, resulting in 1764 athletic training services and 117 physician encounters. Bone-stress injuries represented 20% of all injuries reported by cross-country athletes. The average BSI rate was 0.14 per athlete-season. Injury rates were higher in female (0.16) than male (0.10) athletes and higher in the 2019-2020 season (0.20) than the 2020-2021 (0.14), 2018-2019 (0.12), and 2021-2022 (0.10) seasons. Most BSIs occurred in the lower leg (23.8%) and the foot (23.8%). The majority of injuries were classified as overuse and time loss (72.6%) and accounted for most of the athletic training services (75.3%) and physician encounters (72.6%). We found a mean of 10.89 athletic training services per overuse and time-loss injury and 12.20 athletic training services per overuse and non-time-loss injury. Mean occurrence was lower for physician encounters (0.70), prescription medications (0.04), tests (0.75), procedures (0.01), and surgery (0.02) than for athletic training services (10.50).

CONCLUSIONS

Bone-stress injuries are common in collegiate cross-country runners and require considerable athletic training resources. Athletic trainers should be appropriately staffed for this population, and suspected BSIs should be confirmed with a medical diagnosis. Future investigators should track treatment codes associated with BSI to determine best-practice patterns.

Association of Dynamic Knee Valgus and Bone Stress Injury in US Military Academy Cadets

CONTEXT

Early identification of incoming military personnel at elevated odds for bone stress injury (BSI) is important for the health and readiness of the US military.

DESIGN

Prospective cohort study.

METHODS

Knee kinematic data of the incoming US Military Academy cadets were collected while performing a jump-landing task (The Landing Error Scoring System) using a markerless motion capture system and depth camera. Data on incidence of lower-extremity injury, including BSI, were collected throughout the study period.

RESULTS

A total of 1905 participants (452 females, 23.7%) were examined for knee valgus and BSI status. A total of 50 BSI occurred during the study period (incidence proportion = 2.6%). The unadjusted odds ratio for BSI at initial contact was 1.03 (95% confidence interval [CI], 0.94-1.14; P = .49). Adjusted for sex, the odds ratio for BSI at initial contact was 0.97 (95% CI, 0.87-1.06; P = .47). At the instant of maximum knee-flexion angle, the unadjusted odds ratio was 1.06 (95% CI, 1.02-1.10; P = .01), and the odds ratio was 1.02 (95% CI, 0.98-1.07; P = .29) after adjusting for sex. This suggests that there was not a significant enough association for an increase in the odds of BSI based on either degree of knee valgus.

CONCLUSIONS

Our results did not demonstrate an association between knee valgus angle data during a jump-landing task and future increased odds of BSI in a military training population. Further analysis is warranted, but the results suggests the association between kinematics and BSI cannot be effectively screened by knee valgus angle data in isolation.

Healthy Runner Project: a 7-year, multisite nutrition education intervention to reduce bone stress injury incidence in collegiate distance runners

Objectives

We evaluated the effect of a nutrition education intervention on bone stress injury (BSI) incidence among female distance runners at two NCAA Division I institutions.

Methods

Historical BSI rates were measured retrospectively (2010-2013); runners were then followed prospectively in pilot (2013-2016) and intervention (2016-2020) phases. The primary aim was to compare BSI rates in the historical and intervention phases. Pilot phase data are included only for descriptive purposes. The intervention comprised team nutrition presentations focused on optimising energy availability plus individualised nutrition sessions for runners with elevated Female Athlete Triad risk. Annual BSI rates were calculated using a generalised estimating equation Poisson regression model adjusted for age and institution. Post hoc analyses were stratified by institution and BSI type (trabecular-rich or cortical-rich).

Results

The historical phase included 56 runners and 90.2 person-years; the intervention phase included 78 runners and 137.3 person-years. Overall BSI rates were not reduced from the historical (0.52 events per person-year) to the intervention (0.43 events per person-year) phase. Post hoc analyses demonstrated trabecular-rich BSI rates dropped significantly from 0.18 to 0.10 events per person-year from the historical to intervention phase (p=0.047). There was a significant interaction between phase and institution (p=0.009). At Institution 1, the overall BSI rate dropped from 0.63 to 0.27 events per person-year from the historical to intervention phase (p=0.041), whereas no decline was observed at Institution 2.

Conclusion

Our findings suggest that a nutrition intervention emphasising energy availability may preferentially impact trabecular-rich BSI and depend on team environment, culture and resources.

Link Between the Female Athlete Triad and Gymnastics-Related Injury in Retired Collegiate Gymnasts

OBJECTIVES

To compare gymnastics-related injuries between former collegiate gymnasts who did and did not report components of the female athlete triad (Triad) during college, including disordered eating or menstrual irregularity. We hypothesized that athletes reporting these 2 triad symptoms would have higher rates of time loss injury and injuries requiring surgery.

DESIGN

Retrospective case-control.

SETTING

Online survey.

PATIENTS

Four hundred seventy former collegiate gymnasts.

INTERVENTIONS

Athletes completed online survey distributed through social media.

MAIN OUTCOME MEASURES

Participants were grouped based on self-reported menstrual irregularity and disordered eating during college. We compared time loss injuries, injuries resulting in surgery, and injury locations between the groups using χ2 analyses.

RESULTS

Seventy percent (n = 328) of participants in this study reported a time loss college injury without surgery, and 42% (n = 199) reported an injury during college that required surgical treatment. A significantly greater proportion of gymnasts with only disordered eating reported a time loss gymnastics injury (without surgery) compared with those who reported only menstrual irregularity during college (79% vs 64%; P =0 .03). A significantly greater proportion of the disordered eating-only group reported a spine injury compared with the menstrual irregularity-only group (P = 0.007) and the group who reported neither menstrual irregularity nor disordered eating (P = 0.006).

CONCLUSIONS

College gymnasts who experienced disordered eating were more likely to experience a nonsurgical time loss injury while in college, as well as spine injury compared with those with menstrual irregularity. Sports medicine providers should be aware of the association between injuries and individual components of Triad in gymnasts beyond bone stress injuries.

Support for inadvertent undereating in female adolescent athletes with clinical indicators of low energy availability

OBJECTIVES

This study evaluated pathways to low energy availability in a sample of female adolescent athletes (n = 464).

DESIGN

Cross-sectional.

METHODS

Participants (age 13-18 y) underwent assessments for height, weight, eating attitudes and behaviors, and menstrual function. Bone mineral density and body composition were evaluated by dual-energy x-ray absorptiometry in a subset of participants (n = 209). Athletes were classified with clinical indicators of low energy availability if they met criteria for 1) primary or secondary amenorrhea or 2) clinical underweight status (body mass index-for-age < 5th percentile). Disordered eating was assessed using the Eating Disorder Examination Questionnaire.

RESULTS

Thirty (6.5%) athletes exhibited clinical indicators of low energy availability, with higher estimates in leanness than non-leanness sports (10.9% vs. 2.1%, p < 0.005). Among athletes with clinical indicators of low energy availability, 80% (n = 24) did not meet criteria for disordered eating, eating disorder, or report the desire to lose weight. Athletes with (vs. without) clinical indicators of low energy availability exhibited lower lumbar spine (-1.30 ± 1.38 vs. -0.07 ± 1.21, p < 0.001) and total body (-0.30 ± 0.98 vs. 0.53 ± 0.97, p < 0.006) bone mineral density Z-scores.

CONCLUSIONS

A majority of female adolescent athletes with clinical indicators of low energy availability did not exhibit characteristics consistent with intentional dietary restriction, supporting the significance of the inadvertent pathway to low energy availability and need for increased nutrition education in this population.

Effect of Running-Induced Fatigue on Tibial Acceleration and the Role of Lower Limb Muscle Strength, Power, and Endurance

BACKGROUND

High-impact loads have been linked with running injuries. Fatigue has been proposed to increase impact loads, but this relationship has not been rigorously examined, including the associated role of muscle strength, power, and endurance.

PURPOSE

This study aimed to investigate the effect of fatigue on impact loading in runners and the role of muscle function in mediating changes in impact loading with fatigue.

METHODS

Twenty-eight trained endurance runners performed a fixed-intensity time to exhaustion test at 85% of V̇O 2max . Tibial accelerations were measured using leg-mounted inertial measurement units and sampled every minute until volitional exhaustion. Tests of lower limb muscle strength, power, and endurance included maximal isometric strength (soleus, knee extensors, and knee flexors), single leg hop for distance, and the one leg rise test. Changes in peak tibial acceleration (PTA, g ) were compared between time points throughout the run (0%, 25%, 50%, 75%, and 100%). Associations between the change in PTA and lower limb muscle function tests were assessed (Spearman's rho [ rs ]).

RESULTS

PTA increased over the duration of the fatiguing run. Compared with baseline (0%) (mean ± SD, 9.1 g ± 1.6 g ), there was a significant increase at 75% (9.9 g ± 1.7 g , P = 0.001) and 100% (10.1 g ± 1.8 g , P < 0.001), with no change at 25% (9.6 g ± 1.6 g , P = 0.142) or 50% (9.7 g ± 1.7 g , P = 0.053). Relationships between change in PTA and muscle function tests were weak and not statistically significant ( rs = -0.153 to 0.142, all P > 0.05).

CONCLUSIONS

Peak axial tibial acceleration increased throughout a fixed-intensity run to exhaustion. The change in PTA was not related to performance in lower limb muscle function tests.

Identifying latent classes of Relative Energy Deficiency in Sport (RED-S) consequences in a sample of collegiate female cross country runners

OBJECTIVE

The purpose of this study was to identify patterns of clustering of the 10 health consequences identified in the Relative Energy Deficiency in Sport (RED-S) framework among collegiate female Cross-Country runners. We also assessed risk characteristics associated with each cluster.

METHODS

This randomly sampled population included 211 current National Collegiate Athletics Association (NCAA) Division I (DI) female cross country runners who completed a quantitative survey. We used latent class analysis (LCA) to group athletes into mutually exclusive classes based on shared response patterns of RED-S consequences. We computed descriptive statistics to identify demographics, personal characteristics, disordered eating and emotional health characteristics associated with each class.

RESULTS

The average age of the sample was 21 years with mean body mass index 20.4 kg/m². The LCA identified three unique classes of potential RED-S presentations: (1) low probability of RED-S consequences; (2) complex physical and psychological concerns with a higher burden of cardiovascular concern and (3) very high probability of anxiety with high burden of menstrual disturbance, bone injury and gastrointestinal concern. All classes were characterised by high levels of menstrual disturbance and distinguished by the number and burden of other potential RED-S consequences and in reported abuse history, emotional regulation and perfectionism.

CONCLUSION

This study identified a high burden of menstrual disturbance in NCAA D1 cross country runners, and three unique presentations of RED-S consequences. Future research is warranted to better understand how early prevention and intervention strategies may mitigate RED-S consequences in distance runners.

How Advancement in Bone Science Should Inform the Examination and Treatment of Femoral Shaft Bone Stress Injuries in Running Athletes

Stress fractures likely have a 1-2% incidence in athletes in general. In runners, a more vulnerable population, incidence rates likely range between 3.2 and 21% with female runners having greater susceptibility. The incidence of femoral shaft stress fractures is less well known. New basic and translational science research may impact the way clinicians diagnose and treat femoral stress fractures. By using a fictitious case study, this paper applies bone science to suggest new approaches to evaluating and treating femoral shaft stress fractures in the running population.

Stress fractures

Stress fractures (SF) represent 10%-20% of all injuries in sport medicine. An SF occurs when abnormal and repetitive loading is applied on normal bone: The body cannot adapt quickly enough, leading to microdamage and fracture. The etiology is multifactorial with numerous risk factors involved. Diagnosis of SF can be achieved by identifying intrinsic and extrinsic factors, obtaining a good history, performing a physical exam, and ordering laboratory and imaging studies (magnetic resonance imaging is the current gold standard). Relative energy deficiency in sport (RED-S) is a known risk factor. In addition, for women, it is very important know the menstrual status to identify long periods of amenorrhea in the past and the present. Early detection is important to improve the chance of symptom resolution with conservative treatment. Common presentation involves complaints of localized pain, with or without swelling, and tenderness on palpation of bony structures that begins earlier in training and progressively worsens with activity over a 2- to 3-week period. Appropriate classification of SF based on type, location, grading, and low or high risk is critical in guiding treatment strategies and influencing the time to return to sport. Stress injuries at low-risk sites are typically managed conservatively. Studies have suggested that calcium and vitamin D supplementation might be helpful. Moreover, other treatment regimens are not well established. Understanding better the pathophysiology of SFs and the potential utility of current and future bone-active therapeutics may well yield approaches that could treat SFs more effectively.

Comparison of Ultrasonography to MRI in the Diagnosis of Lower Extremity Bone Stress Injuries: A Prospective Cohort Study

OBJECTIVE

To determine the sensitivity and specificity of ultrasound imaging (USI) compared to the reference-standard of MRI in the diagnosis of bone stress injury (BSI).

METHODS

A prospective blinded cohort study was conducted. Thirty seven patients who presented to an academic sports medicine clinic from 2016 to 2020 with suspected lower-extremity BSI on clinical exam underwent both magnetic resonance imaging (MRI) and USI. Participant characteristics were collected including age, gender and sport. Exclusion criteria included contraindication for dedicated MRI, traumatic fracture, or severe tendon or ligamentous injury. The primary outcome measure was BSI diagnosis by USI. An 8-point assessment system was utilized on USI for diagnosis of BSI, and the Fredericson and Nattiv²² criteria were applied to classify MRI findings.

RESULTS

Thirty seven participants who met study criteria were consented to participate. All participants completed baseline measures. Using MRI, there were 30 (81%) athletes with a positive and seven participants with a negative BSI diagnosis. The most common BSIs in the study were in the metatarsal (54%) and tibia (32%). Compared to MRI, USI demonstrated 0.80 sensitivity (95% confidence interval [CI], 0.61-0.92) and 0.71 specificity (95% CI, 0.29-0.96) in detecting BSI, with a positive predictive value of 0.92 (95% CI, 0.75-0.99) and negative predictive value of 0.45 (95% CI, 0.17-0.77).

CONCLUSIONS

USI is a potentially useful point-of-care tool for practicing sports medicine providers to combine with their clinical evaluation in the diagnosis of BSIs. Further research is ongoing to determine the role of USI in follow-up care and return-to-play protocols.

Impaired Bone Microarchitecture at Distal Radial and Tibial Reference Locations Is Not Related to Injury Site in Athletes With Bone Stress Injury

BACKGROUND

Bone stress injuries (BSIs) are common sports injuries that occur because of an imbalance between microdamage accumulation and removal through bone remodeling. The underlying bone phenotype has been assumed to be a contributing factor. However, the bone microarchitecture of athletes with BSI is not well characterized, and no study has investigated whether impaired bone microarchitecture is associated with bone composition or anatomic site of injury.

PURPOSE/HYPOTHESIS

This cross-sectional study characterizes the bone microarchitecture at distal radial and tibial reference locations in athletes with BSI. Based on previous dual-energy X-ray absorptiometry (DXA) findings, the aim was to compare anatomic injury sites, hypothesizing that athletes with BSIs in bones with greater trabecular composition show impaired bone microarchitecture parameters compared with those with BSIs in bones with greater cortical composition.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Athletes who had presented to our outpatient clinic because of a high-grade BSI (ie, stress fracture) were retrospectively included. Blood and urine samples were collected. Areal bone mineral density (aBMD) was assessed by DXA at the lumbar spine and both hips. Bone microarchitecture was analyzed by high-resolution peripheral quantitative computed tomography (HR-pQCT) at the distal radius and tibia. HR-pQCT parameters were expressed in relation to available sex-, age-, and device-adjusted reference values and compared with a cohort of 53 age- and sex-matched controls.

RESULTS

In total, 53 athletes had a BSI of the foot (n = 20), tibia/fibula (n = 18), pelvis (n = 9), femur (n = 5), or sternum (n = 1). Based on DXA measurements, a Z-score of -1.0 or lower was found in 32 of 53 (60.4%) of the athletes, of whom 16 of 53 (30.2%) had a Z score -2.0 or lower. While an impairment of cortical area (P = .034 and P = .001) and thickness (P = .029 and P < .001) was detected at the distal radius and tibia in the BSI cohort compared with controls, no differences in BMD or bone microarchitecture were observed between anatomic injury sites. Furthermore, no difference was revealed when BSIs were grouped into cortical- and trabecular-rich sites.

CONCLUSION

Reduced aBMD and impaired cortical bone microarchitecture were present in a considerable number of athletes with BSI. Neither aBMD nor bone microarchitecture was related to the injury site, highlighting the multifactorial etiology of BSI.

Running-related injuries in middle school cross-country runners: Prevalence and characteristics of common injuries

BACKGROUND

Understanding the prevalence and factors associated with running-related injuries in middle school runners may guide injury prevention.

OBJECTIVE

To determine the prevalence of running-related injuries and describe factors related to a history of injury.

DESIGN

Retrospective cross-sectional study.

SETTING

Survey distributed online to middle school runners.

METHODS

Participants completed a web-based survey regarding prior running-related injuries, training, sleep, diet, and sport participation.

MAIN OUTCOME MEASUREMENTS

Prevalence and characteristics differentiating girls and boys with and without running-related injury history adjusted for age.

PARTICIPANTS

Youth runners (total: 2113, average age,  13.2 years; boys: n = 1255, girls: n = 858).

RESULTS

Running-related injuries were more prevalent in girls (56% vs. 50%, p = .01). Ankle sprain was the most common injury (girls: 22.5%, boys: 21.6%), followed by patellofemoral pain (20.4% vs. 7.8%) and shin splints (13.6% vs. 5.9%); both were more prevalent in girls (p < .001). Boys more frequently reported plantar fasciitis (5.6% vs. 3.3%, p = .01), iliotibial band syndrome (4.1% vs. 1.4%, p = .001) and Osgood-Schlatter disease (3.8% vs. 1.2%, p = .001). Runners with history of running-related injuries were older, ran greater average weekly mileage, ran faster, had fewer average hours of sleep on weekends, skipped more meals, missed breakfast, and consumed less milk (all p < .05). Girls with history of running-related injuries reported higher dietary restraint scores, later age of menarche, more menstrual cycle disturbances, and higher likelihood of following vegetarian diets and an eating disorder diagnosis (all p < .05). Runners with no history of running-related injuries were more likely to have participated in ≥2 years of soccer or basketball (p < .001).

CONCLUSIONS

Most middle school runners reported a history of running-related injuries and certain injuries differing by gender. Modifiable factors with the greatest association with running-related injuries included training volume, dietary restraint, skipping meals, and less sleep. Sport sampling, including participation in ball sports, may reduce running-related injury risk in this population.

Medical and Biomechanical Risk Factors for Incident Bone Stress Injury in Collegiate Runners: Can Plantar Pressure Predict Injury?

Background:

Bone stress injury (BSI) is a common reason for missed practices and competitions in elite track and field runners.

Hypothesis:

It was hypothesized that, after accounting for medical risk factors, higher plantar loading during running, walking, and athletic movements would predict the risk of future BSI in elite collegiate runners.

Study Design:

Cohort study; Level of evidence, 2.

Methods:

A total of 39 elite collegiate runners (24 male, 15 female) were evaluated during the 2014-2015 academic year to determine the degree to which plantar pressure data and medical history (including Female and Male Athlete Triad risk factors) could predict subsequent BSI. Runners completed athletic movements while plantar pressures and contact areas in 7 key areas of the foot were recorded, and the measurements were reported overall and by specific foot area. Regression models were constructed to determine factors related to incident BSI.

Results:

Twenty-one runners (12 male, 9 female) sustained ≥1 incident BSI during the study period. Four regression models incorporating both plantar pressure measurements and medical risk factors were able to predict the subsequent occurrence of (A) BSIs in female runners, (B) BSIs in male runners, (C) multiple BSIs in either male or female runners, and (D) foot BSIs in female runners. Model A used maximum mean pressure (MMP) under the first metatarsal during a jump takeoff and only misclassified 1 female with no BSI. Model B used increased impulses under the hindfoot and second through fifth distal metatarsals while walking, and under the lesser toes during a cutting task, correctly categorizing 83.3% of male runners. Model C used higher medial midfoot peak pressure during a shuttle run and triad cumulative risk scores and correctly categorized 93.3% of runners who did not incur multiple BSIs and 66.7% of those who did. Model D included lower hindfoot impulses in the shuttle run and higher first metatarsal MMP during treadmill walking to correctly predict the subsequent occurrence of a foot BSI for 75% of women and 100% without.

Conclusion:

The models collectively suggested that higher plantar pressure may contribute to risk for BSI.

Restrictive Eating and Prior Low-Energy Fractures Are Associated With History of Multiple Bone Stress Injuries

Bone stress injuries (BSIs) are common among athletes and have high rates of recurrence. However, risk factors for multiple or recurrent BSIs remain understudied. Thus, we aimed to explore whether energy availability, menstrual function, measures of bone health, and a modified Female Athlete Triad Cumulative Risk Assessment (CRA) tool are associated with a history of multiple BSIs. We enrolled 51 female runners (ages 18-36 years) with history of ≤1 BSI (controls; n = 31) or ≥3 BSIs (multiBSI; n = 20) in this cross-sectional study. We measured lumbar spine, total hip, and femoral neck areal bone mineral density by dual-energy X-ray absorptiometry, bone material strength index using impact microindentation, and volumetric bone mineral density, microarchitecture, and estimated strength by high-resolution peripheral quantitative computed tomography. Participants completed questionnaires regarding medical history, low-energy fracture history, and disordered eating attitudes. Compared with controls, multiBSI had greater incidence of prior low-energy fractures (55% vs. 16%, p = .005) and higher modified Triad CRA scores (2.90 ± 2.05 vs. 1.84 ± 1.59, p = .04). Those with multiBSI had higher Eating Disorder Examination Questionnaire (0.92 ± 1.03 vs. 0.46 ± 0.49, p = .04) scores and a greater percentage difference between lowest and highest body mass at their current height (15.5% ± 6.5% vs. 11.5% ± 4.9% p = .02). These preliminary findings indicate that women with a history of multiple BSIs suffered more prior low-energy fractures and have greater historical and current estimates of energy deficit compared with controls. Our results provide strong rationale for future studies to examine whether subclinical indicators of energy deficit contribute to risk for multiple BSIs in female runners.

Female Athlete Hip Injuries: A Narrative Review

OBJECTIVE

In this narrative review, we highlight sex-specific anatomic and biomechanical features of the hip region in female athletes, as well as the potential impact of these characteristics on observed disparities in both intra-articular and extra-articular injury patterns between female and male athletes. It is our goal to broaden the scope of knowledge related to hip pathology in active female athletes among sports medicine providers with the hope of better optimizing sport participation and performance in female athletes.

DATA SOURCES

A literature review was conducted using PubMed database and Google Scholar search engine. Search terms included sport, female, athlete, sex differences, injury, hip, and all diagnoses discussed in this review. Cross-reference of these articles identified additional resources.

MAIN RESULTS

Sex-specific differences in both static design and dynamic function contribute to disparities in hip injury patterns between female and male athletes. Intra-articular injuries, including labral and ligamentum teres pathology, as well as extra-articular injuries, including iliopsoas tendon dysfunction, gluteal and proximal hamstring tendinopathy, ischiofemoral impingement, bone stress injuries, and certain nerve entrapment syndromes, seem to affect female athletes more commonly than male counterparts.

CONCLUSIONS

Given unique anatomic and functional considerations, the growing population of female athletes worldwide warrants specialized care and consideration. Potential predisposition to specific hip injuries should be taken into consideration during diagnostic evaluation of hip pain in the female athlete.

Training Management of the Elite Adolescent Soccer Player throughout Maturation

Professional soccer clubs invest significantly into the development of their academy prospects with the hopes of producing elite players. Talented youngsters in elite development systems are exposed to high amounts of sports-specific practise with the aims of developing the foundational skills underpinning the capabilities needed to excel in the game. Yet large disparities in maturation status, growth-related issues, and highly-specialised sport practise predisposes these elite youth soccer players to an increased injury risk. However, practitioners may scaffold a performance monitoring and injury surveillance framework over an academy to facilitate data-informed training decisions that may not only mitigate this inherent injury risk, but also enhance athletic performance. Constant communication between members of the multi-disciplinary team enables context to build around an individual's training status and risk profile, and ensures that a progressive, varied, and bespoke training programme is provided at all stages of development to maximise athletic potential.

Can a Modified Y-Balance Test Predict Running Overuse Injuries over the Course of a Division I Collegiate Cross-Country Season?

BACKGROUND

Collegiate distance runners often suffer from running overuse injuries (ROI). The Y-Balance Test (YBT) has the potential to predict ROI risk in collegiate runners.

PURPOSE

To investigate whether a preseason clinical assessment of dynamic balance, through a modified version of the YBT (mYBT), can predict risk of ROIs during one NCAA Division I cross-country (XC) season.

STUDY DESIGN

Prospective case-control study.

METHODS

Participants from a Division I XC team were screened for mYBT performance in four directions: anterior (AN), posteromedial (PM), posterolateral (PL), and posterior (PO). ROIs were tracked over the course of the XC season. Receiver operating characteristic (ROC) curve analysis (α = 0.05) was utilized to investigate the effectiveness of the mYBT in predicting injury risk.

RESULTS

Nine (5 female, 4 male) of 29 runners developed an ROI during the XC season. Five components of the mYBT were found to predict injuries, including normalized nondominant PO score (AUC = 0.756, p = 0.03; RR = 1.90), AN raw difference and limb asymmetry (AUC = 0.808, p = 0.01), and PM raw difference and limb asymmetry in males (AUC = 0.958, p = 0.02).

CONCLUSION

Specific components of the mYBT can help predict the risk of developing a running overuse injury over one Division I XC season.

LEVEL OF EVIDENCE

Screening, Level 3.

Runner's Health Choices Questionnaire: Male College Cross-Country Runners' Perspectives on Health and Eating

CONTEXT

Competitive cross-country runners train at much higher loads and with greater demands than recreational runners, posing a unique set of physiological and psychological challenges. Thus, identification of factors influencing health and nutritional choices in male cross-country runners is needed to help combat energy-related health issues.

PURPOSE

To assess male college cross-country runners' perspectives regarding sport-related health and the factors impacting their eating behaviors.

DESIGN

Cross-sectional survey.

PARTICIPANTS/METHODS

The Runner's Health Choices Questionnaire was distributed to male college cross-country runners. Responses were analyzed using quantitative descriptive statistics.

RESULTS

One hundred nineteen runners completed the survey. Runners reported a diverse range of factors impacting eating and health behaviors from athletic performance enhancement to enjoyment of food. Less than 6% of athletes ranked athletic trainer, registered dietitian, or physician as often consulted for nutrition/health information. However, 75% of runners said they would be somewhat likely or very likely to make dietary or health changes if given new or additional information by a health care provider.

CONCLUSION

Male cross-country runners appear to try to balance a global desire to be healthy with individual preferences. Athletes may be receptive to nutritional education that utilizes a biopsychosocial model with mental and psychological health support, and intentional effort is needed to support runners' overall health.

Incidence of Undiagnosed Celiac Disease Presenting as Bone Stress Injuries to a Sport and Exercise Medicine Clinic

OBJECTIVE

To evaluate the incidence of undiagnosed celiac disease (CD) in patients presenting with bone stress injuries (BSI) to a NHS Sport and Exercise Medicine (SEM) clinic.

DESIGN

Retrospective cohort study.

SETTING

Single tertiary-level SEM clinic.

PATIENT/PARTICIPANTS

One hundred consecutive patients with radiologically proven BSIs.

INTERVENTIONS

Laboratory blood tests (LBT) can unmask underlying metabolic bone disorders. Anti-tissue transglutaminase antibody (TTG) testing has a high sensitivity and specificity for CD. In this SEM clinic, clinicians were encouraged to perform LBT including TTG, at time of diagnosis of BSI. A retrospective analysis of age, sex, fracture site, co-morbidities, TTG result, and subsequent investigations was performed.

MAIN OUTCOME MEASURES

The primary outcome was the number and percentage of patients with BSIs and either positive TTG (CD seropositivity) or a diagnosis of CD.

RESULTS

Of the 100 patients with radiologically proven BSIs, 70% were female, and the mean age was 37 years (range 16-69). Eighty-five percent had the appropriate LBTs, of which 70% (60/85) were female, and the mean age was 37(16-69). Metatarsal (35%) and tibial (21%) were the most common BSIs. Anti-tissue transglutaminase antibody was performed in 85 patients. Two patients (2/85) had pre-existing CD and were excluded from incidence calculations. Five patients [5/83 (6%), mean age 38 years (28-57), 80% female] had a positive TTG, of whom 3 have subsequently had CD confirmed by endoscopic biopsy. Four patients with a positive TTG underwent dual-energy X-ray absorptiometry with osteopenia found in 3 (75%) cases.

CONCLUSIONS

In this cohort, the incidence of CD seropositivity was 6%, and the prevalence of biopsy-confirmed CD was 5%, approximately 5-fold higher than UK population estimates. Anti-tissue transglutaminase antibody screening for CD should be considered in all patients presenting with BSIs.

Comprehensive Return to Competitive Distance Running: A Clinical Commentary

Running injuries are very common, and there are well-established protocols for clinicians to manage specific musculoskeletal conditions in runners. However, competitive and elite runners may experience different injuries than the average recreational runner, due to differences in training load, biomechanics, and running experience. Additionally, injury-specific rehabilitation protocols do not consider the broader goal of return to competitive running, including the unique psychosocial and cardiorespiratory fitness needs of elite athletes. This review aims to suggest a guideline for running-specific progression as part of a comprehensive rehabilitation program for injured competitive runners. Tools to evaluate an athlete's psychosocial preparedness to return to competition are presented. Recommendations are also provided for monitoring cardiorespiratory fitness of injured runners, including the nuances of interpreting these data. Finally, a six-phase training paradigm is proposed to guide clinicians as they help competitive runners transition from the early stages of injury through a full return to competition.

Epidemiology of NCAA Bone Stress Injuries: A Comparison of Athletes in Divisions I, II, and III

Background:

Bone stress injuries (BSIs) are a major source of functional impairment in athletes of all sports, with many risk factors, including athlete characteristics and type of sport. In National Collegiate Athletic Association (NCAA) athletics, the stratification of programs into divisions with different characteristics and makeup has been identified as increasing the risk for certain kinds of injuries, but there have been no studies on the difference of BSI rates and characteristics between athletes in Division I (DI) and those in Divisions II and III (DII and DIII).

Purpose/Hypothesis:

To characterize the BSI rates in each division and compare the incidence and characteristics of BSIs within divisions. Our hypothesis was that BSI rates would be higher in DII and DIII athletes as compared with DI athletes.

Study Design:

Descriptive epidemiology study.

Methods:

Five years of recorded BSI data in collegiate athletes via the NCAA Injury Surveillance Program were examined for the academic years 2009-2010 to 2013-2014. BSI rates per 100,000 athlete-exposures (AEs) were compared for DI versus DII and DIII athletes using risk ratios and 95% CIs. Time lost to injury, time of season of injury, and class composition of injured athletes were also compared between divisions.

Results:

Over the 5 years studied, DII and DIII programs reported 252 BSIs more than 1,793,777 AEs (14.05 per 100,000 AEs), and DI programs reported 235 BSIs over 2,022,592 AEs (11.62 per 100,000 AEs). The risk ratio was significant for D1 versus DII and DIII (1.21; 95% CI, 1.01-1.44). There was a significant difference in time lost to injury in DI versus DII and DIII, χ²(5, n = 449) = 16.54; P = .006. When data were stratified by individual sport, there were no significant divisional differences in high-risk sports.

Conclusion:

In the current study, NCAA DII and DIII athletes had higher rates of BSI than their DI counterparts. As compared with DII and DIII athletes, the DI athletes had a significantly greater proportion of BSIs that did not result in absence from participation in sport.

Adolescent Endurance Runners Exhibit Suboptimal Energy Availability and Intakes of Key Nutrients

Backgroud: Despite the evidence of an elevated prevalence of low bone mass in adolescent endurance runners, reports on dietary intake in this population is limited.Objectives: This study aimed to evaluate energy availability (EA) and dietary intake among 72 (n = 60 female, n = 12 male) high school cross-country runners.Methods: The sample consisted of a combined dataset of two cohorts. In both cohorts, the Block Food Frequency Questionnaire (FFQ; 2005 & 2014 versions) assessed dietary intake. Fat free mass was assessed using dual-energy x-ray absorptiometry or bioelectrical impedance analysis.Results: Mean EA was less than recommended (45 kcal/kgFFM/day) among male (35.8 ± 14.4 kcal/kg FFM/day) and female endurance runners (29.6 ± 17.4 kcal/kgFFM/day), with 30.0% of males and 60.0% of females meeting criteria for low EA (<30 kcal/kgFFM/day). Calorie intake for male (2,614.2 ± 861.8 kcal/day) and female (1,879.5 ± 723.6 kcal/day) endurance runners fell below the estimated energy requirement for "active" boys (>3,100 kcal/day) and girls (>2,300 kcal/day). Female endurance runners' relative carbohydrate intake (4.9 ± 2.1 g/kg/day) also fell below recommended levels (6-10 g/kg/day). Male and female endurance runners exhibited below-recommended intakes of calcium, vitamin D, potassium, fruit, vegetables, grains, and dairy. Compared to male endurance runners, female endurance runners demonstrated lower relative intakes of energy (kcal/kg/day), protein (g/kg/day), fat (g/kg/day), fiber, vegetables, total protein, and oils.Conclusion: This study provides evidence of the nutritional risk of adolescent endurance runners and underscores the importance of nutritional support efforts in this population.

Effects of Low Energy Availability on Bone Health in Endurance Athletes and High-Impact Exercise as A Potential Countermeasure: A Narrative Review

Endurance athletes expend large amounts of energy in prolonged high-intensity exercise and, due to the weight-sensitive nature of most endurance sports, often practice periods of dietary restriction. The Female Athlete Triad and Relative Energy Deficiency in Sport models consider endurance athletes at high-risk for suffering from low energy availability and associated health complications, including an increased chance of bone stress injury. Several studies have examined the effects of low energy availability on various parameters of bone structure and markers of bone (re)modelling; however, there are differences in findings and research methods and critical summaries are lacking. It is difficult for athletes to reduce energy expenditure or increase energy intake (to restore energy availability) in an environment where performance is a priority. Development of an alternative tool to help protect bone health would be beneficial. High-impact exercise can be highly osteogenic and energy efficient; however, at present, it is rarely utilized to promote bone health in endurance athletes. Therefore, with a view to reducing the prevalence of bone stress injury, the objectives of this review are to evaluate the effects of low energy availability on bone health in endurance athletes and explore whether a high-impact exercise intervention may help to prevent those effects from occurring.

Lower step rate is associated with a higher risk of bone stress injury: a prospective study of collegiate cross country runners

OBJECTIVES

To determine if running biomechanics and bone mineral density (BMD) were independently associated with bone stress injury (BSI) in a cohort of National Collegiate Athletic Association Division I cross country runners.

METHODS

This was a prospective, observational study of 54 healthy collegiate cross country runners over three consecutive seasons. Whole body kinematics, ground reaction forces (GRFs) and BMD measures were collected during the preseason over 3 years via motion capture on an instrumented treadmill and total body densitometer scans. All medically diagnosed BSIs up to 12 months following preseason data collection were recorded. Generalised estimating equations were used to identify independent risk factors of BSI.

RESULTS

Univariably, step rate, centre of mass vertical excursion, peak vertical GRF and vertical GRF impulse were associated with BSI incidence. After adjusting for history of BSI and sex in a multivariable model, a higher step rate was independently associated with a decreased risk of BSI. BSI risk decreased by 5% (relative risk (RR): 0.95; 95% CI 0.91 to 0.98) with each one step/min increase in step rate. BMD z-score was not a statistically significant risk predictor in the final multivariable model (RR: 0.93, 95% CI 0.85 to 1.03). No other biomechanical variables were found to be associated with BSI risk.

CONCLUSION

Low step rate is an important risk factor for BSI among collegiate cross country runners and should be considered when developing comprehensive programmes to mitigate BSI risk in distance runners.

Musculoskeletal Injuries in Ultra-Endurance Running: A Scoping Review

Ultra-endurance running (UER) has seen an important increase in participation over the last few decades. Long hours of UER can lead to excessive stress on the body, resulting in musculoskeletal injuries (MSKI). UER is not a uniform sport and events can differ considerably in distance (over 42.195 km), time (e.g., events over 6 h) and multi-day or multi-stage events on various surfaces (e.g., track, on-road, off-road). The aims of this scoping review were therefore: (1) to examine the current evidence of MSKI, providing a synthesis of the most common MSKI by anatomical region and specific diagnosis; (2) categorize MSKI by type of UER activity (competition: time-limited; multi-stage; continuous UER events and training); (3) describe knowledge gaps in the literature and provide advice on potential further research. Our electronic literature search (PubMed, SPORTDiscus, Web of Science) identified a total of 13 studies (9 in competition, and 4 in training). Anatomical site, diagnosis and rate of injuries differ between competition and training as well as between different UER types. MSKI are observed in 18% of multi-stage events (0.7-1.8 injuries/runner and 7.2 injuries/1000 h). Most MSKI involve the lower leg (35.0%), ankle (16.8%), knee (13.1%) and foot (12.6%), with main diagnosis of medial tibial stress syndrome (30.1%) and patella femoral pain syndrome (PFPS; 7.2%). Single, continuous UER events differ between a 1005 km road race with almost all of the injuries due to overuse, with the main anatomical site of the knee (31%), ankle (28%) and lower leg (14%) and main diagnosis of PFPS (15.6%), compared to a 65 km trail race, with 32.8% of MSKI, mainly on the foot [plantar fasciitis (28.6%)], ankle [sprain (28.6%)] and knee. Timed-UER events (injury rate of 2.1 injuries/athlete) observed most injuries on the ankle (36%) and knee (19%), with the main diagnosis of tendinitis of the foot dorsiflexors (30%). Injuries during training most commonly affect, the back (42%), and knee (40%) and bone stress injuries (22%). Main diagnoses include ankle sprain (18%), iliotibial band injury (16%) and Achilles tendinopathy (11%). Future considerations include examining MSKI in different UER events, environments and surfaces, and on larger study populations. Establishing risk factors, examining sex differences and using a standard reporting system of MSKI in UER are also important.

Overuse-Related Injuries of the Musculoskeletal System: Systematic Review and Quantitative Synthesis of Injuries, Locations, Risk Factors and Assessment Techniques

Overuse-related musculoskeletal injuries mostly affect athletes, especially if involved in preseason conditioning, and military populations; they may also occur, however, when pathological or biological conditions render the musculoskeletal system inadequate to cope with a mechanical load, even if moderate. Within the MOVIDA (Motor function and Vitamin D: toolkit for risk Assessment and prediction) Project, funded by the Italian Ministry of Defence, a systematic review of the literature was conducted to support the development of a transportable toolkit (instrumentation, protocols and reference/risk thresholds) to help characterize the risk of overuse-related musculoskeletal injury. The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) approach was used to analyze Review papers indexed in PubMed and published in the period 2010 to 2020. The search focused on stress (overuse) fracture or injuries, and muscle fatigue in the lower limbs in association with functional (biomechanical) or biological biomarkers. A total of 225 Review papers were retrieved: 115 were found eligible for full text analysis and led to another 141 research papers derived from a second-level search. A total of 183 papers were finally chosen for analysis: 74 were classified as introductory to the topics, 109 were analyzed in depth. Qualitative and, wherever possible, quantitative syntheses were carried out with respect to the literature review process and quality, injury epidemiology (type and location of injuries, and investigated populations), risk factors, assessment techniques and assessment protocols.

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.

Evaluating the Clinical Tests for Adolescent Tibial Bone Stress Injuries

BACKGROUND

Tibial bone stress injuries are common among the athletic adolescent population. A thorough patient history and clinical examination are essential to identify the location and extent of injury. However, there has been little description or any validation of clinical tests to help guide clinicians. Consequently, a formal diagnosis is usually dependent on results from proper imaging.

HYPOTHESIS

Clinical examinations will be both highly sensitive and specific determining the incidence, grade, and location of tibial bone stress injury as compared with magnetic resonance imaging (MRI).

STUDY DESIGN

Case-control.

LEVEL OF EVIDENCE

Level 2.

METHODS

A total of 80 consecutive athletic adolescents, from various sports, with greater than 1-week history of shin pain were enrolled in this institutional review board-approved study. Exclusion criteria were age >19 years and history of traumatic injury. Patients underwent a standardized clinical examination, which included a fulcrum test (FT), tap/percussion test (TT), vibration test (VT) utilizing a 128-Hz tuning fork, weight bearing lunge test (WBLT) to determine degree of dorsiflexion range of motion (ROM), and vertical single leg hop test (VSLHT) for height, landing, and pain. Bilateral lower extremity MRI was completed on the same day as clinical evaluation and served as the injury reference. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated to evaluate each clinical examination for its ability to identify a bone stress injury.

RESULTS

A total of 159 tibiae in 80 patients were evaluated. No single test or combination of tests was both highly sensitive and specific. Individual clinical tests demonstrated sensitivity ranging from 0.11 to 0.72 and specificity ranging from 0.37 to 0.93. The VSLHT noting an increase in pain was the most sensitive test (0.72; 95% CI, 0.62-0.78); however, its specificity was only 0.37 (95% CI, 0.19-0.55), with a PPV of 0.84 (95% CI, 0.78-0.91) and NPV of 0.20 (95% CI, 0.089-0.31). The WBLT demonstrated a mean ROM of 8 cm, with side-to-side differences (range 0-4 cm) not influencing incidence of injury. Combinations of tests demonstrated low sensitivity (0.03-0.40), with better specificity (0.63-1.0). When considering ability to identify higher grades of injury (grade III/IV), all tests had a high NPV indicating that if clinical tests were negative, there was a high likelihood that the patient did not have a grade III or IV injury.

CONCLUSION

No single test or combination of tests was both highly sensitive and specific. Clinicians cannot solely rely on clinical examination for determining extent or severity of bone stress injury in the athletic adolescent population, but when combinations of tests are negative, there is likely not a high-grade bone stress injury.

CLINICAL RELEVANCE

Clinical tests utilized in the evaluation of adolescent tibial bone stress injury may help indicate the presence or absence of higher grade tibial bone stress injury.

Bilateral Looser zones or pseudofractures in the anteromedial tibia as a component of medial tibial stress syndrome in athletes

PURPOSE

Medial tibial stress syndrome (MTSS) represents a common diagnosis in individuals exposed to repetitive high-stress loads affecting the lower limb, e.g., high-performance athletes. However, the diagnostic approach and therapeutic regimens are not well established.

METHODS

Nine patients, diagnosed as MTSS, were analyzed by a comprehensive skeletal analysis including laboratory bone turnover parameters, dual-energy X-Ray absorptiometry (DXA), and high-resolution peripheral quantitative computed tomography (HR-pQCT).

RESULTS

In 4/9 patients, bilateral pseudofractures were detected in the mid-shaft tibia. These patients had significantly lower levels of 25-hydroxycholecalciferol compared to patients with MTSS but similar levels of bone turnover parameters. Interestingly, the skeletal assessment revealed significantly higher bone mineral density (BMD) Z-scores at the hip (1.3 ± 0.6 vs. - 0.7 ± 0.5, p = 0.013) in patients with pseudofractures and a trend towards higher bone microarchitecture parameters measured by HR-pQCT at the distal tibia. Vitamin D supplementation restored the calcium-homeostasis in all patients. Combined with weight-bearing as tolerated, pseudofractures healed in all patients and return to competition was achieved.

CONCLUSION

In conclusion, deficient vitamin D levels may lead to pseudofractures due to localized deterioration of mineralization, representing a pivotal component of MTSS in athletes with increased repetitive mechanical loading of the lower limbs. Moreover, the manifestation of pseudofractures is not a consequence of an altered BMD nor microarchitecture but appears in patients with exercise-induced BMD increase in combination with reduced 25-OH-D levels. The screening of MTSS patients for pseudofractures is crucial for the initiation of an appropriate treatment such as vitamin D supplementation to prevent a prolonged course of healing or recurrence.

LEVEL OF EVIDENCE

III.

A rs936306 C/T Polymorphism in the CYP19A1 Is Associated With Stress Fractures

Kumagai, H, Miyamoto-Mikami, E, Kikuchi, N, Kamiya, N, Zempo, H, and Fuku, N. A rs936306 C/T polymorphism in the CYP19A1 is associated with stress fractures. J Strength Cond Res XX(X): 000-000, 2020-A stress fracture (SF) is an overuse injury, and low bone mineral density (BMD) is the risk factor for the SF. Estrogen is suggested to have a crucial role in bone metabolism, and estrogen-related genetic polymorphisms are associated with BMD. However, the possible association between SF and estrogen-related genetic polymorphisms has not been clarified yet. Therefore, we aimed to clarify whether estrogen-related genetic polymorphisms are associated with a history of SFs in Japanese athletes. A total of 1,311 (men: n = 868, women: n = 443) top-level Japanese athletes who participated in various sports and at different levels were analyzed. The history of SFs was assessed using a questionnaire, and the cytochrome P450 aromatase gene (CYP19A1) rs936306 C/T and estrogen receptor α gene (ESR1) rs2234693 T/C polymorphisms were analyzed using the TaqMan genotyping assay. The genotype frequency of the CYP19A1 C/T polymorphism was significantly different between the injured group and noninjured group under the C allele additive genetic model (odds ratio = 1.31, 95% confidence interval = 1.01-1.70), especially in men and in women with irregular menstruation. On the other hand, there were no significant differences with the ESR1 T/C polymorphism. This study demonstrated that the C allele in the CYP19A1 rs936306 polymorphism is a risk factor for SFs in top-level Japanese athletes.

Impact-Related Ground Reaction Forces Are More Strongly Associated With Some Running Injuries Than Others

BACKGROUND

Inconsistent associations have been reported for impact-related ground reaction force variables and running injuries when grouping all injuries together. However, previous work has shown more consistent associations when focusing on specific injuries.

PURPOSE

To compare ground reaction force variables between healthy and injured runners as a group and within specific common injuries.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 125 runners presenting with patellofemoral pain, tibial bone stress injury, plantar fasciitis, Achilles tendinopathy, or iliotibial band syndrome and 65 healthy controls completed an instrumented treadmill assessment at a self-selected speed. Impact-related ground reaction force variables included vertical average (VALR) and instantaneous (VILR) load rates, posterior and medial/lateral instantaneous load rates, and vertical stiffness at initial loading (VSIL). Mean comparisons were made between the general and specific injury and control groups (α = .05). Cutoff thresholds were established and evaluated using several criteria.

RESULTS

VALR (+17.5%; P < .01), VILR (+15.8%; P < .01), and VSIL (+19.7%; P < .01) were significantly higher in the overall injured versus control groups. For individual injuries, VALR, VILR, and VSIL were significantly higher for patellofemoral pain (+23.4%-26.4%; P < .01) and plantar fasciitis (+17.5%-29.0%; P < .01), as well as VSIL for Achilles tendinopathy (+29.4%; P < .01). Cutoff thresholds showed better diagnostic criteria for individual versus grouped injuries.

CONCLUSION

Impact variables (VALR, VILR, and VSIL) were significantly higher when assessing the injured group as a whole. However, these findings were driven by specific injury groups, highlighting the importance of taking an injury-specific approach to biomechanical risk factors for running injury.

CLINICAL RELEVANCE

These results suggest that practitioners may want to address impact loading in their treatment of injured runners, especially in those with patellofemoral pain and plantar fasciitis.

Reliability of wearable sensors to assess impact metrics during sport-specific tasks

There is little information on the reliability of inertial measurement units for capturing impact load metrics during sport-specific movements. The purpose of this study is to determine the reliability of the Blue Trident IMU sensors in measuring impact load, step count and cumulative bone stimulus during a series of soccer-related tasks. Ten healthy recreational soccer players (age: 27.9 ± 2.18; height: 1.77 ± 0.10 m; mass: 79.02 ± 13.07 kg) volunteered for a 3-visit study and performed 4 tasks. Bilateral impact load, total number of steps and cumulative bone stimulus during the tasks were collected. Data were sampled using a dual-g sensor. Intraclass correlation coefficients (ICC_3,1) with 95% confidence intervals assessed between-day reliability. Impact load (0.58-0.89) and cumulative bone stimulus (0.90-0.97) had good to excellent reliability across tasks. ICC values for right/left step count were good to excellent during acceleration-deceleration (0.728-0.837), change direction (0.734-0.955) and plant/cut manoeuvres (0.701-0.866) and fair to good during the ball kick (0.588-0.683). This suggests that wearable sensors can reliably measure the cumulative impact load during outdoor functional movements; however, kicking manoeuvres are less reliable. Measuring impact load in the field expands the ability to capture more ecologically valid data.

A Primer on Running for the Orthopaedic Surgeon

Long-distance running has become increasingly popular during the past decades. Many running patients pose questions to their orthopaedic surgeons regarding risks, benefits, and running techniques. This article identifies 11 running-related questions that patients may ask and provides information to help answer those questions. This review discusses data on the health benefits of running, common running injuries, the relationship between running and osteoarthritis, recommendations regarding running after orthopaedic surgery, running shoes, and other questions that may arise when treating the running athlete.

Are There Benefits from the Use of Fish Oil Supplements in Athletes? A Systematic Review

Despite almost 25 y of fish oil supplementation (FS) research in athletes and widespread use by the athletic community, no systematic reviews of FS in athletes have been conducted. The objectives of this systematic review are to: 1) provide a summary of the effect of FS on the athlete's physiology, health, and performance; 2) report on the quality of the evidence; 3) document any side effects as reported in the athlete research; 4) discuss any risks associated with FS use; and 5) provide guidance for FS use and highlight gaps for future research. Electronic databases (PubMed, Embase, Web of Science, Google Scholar) were searched up until April 2019. Only randomized placebo-controlled trials (RCTs) in athletes, assessing the effect of FS on a health, physiological/biochemical, or performance variable were included. Of the 137 papers identified through searches, 32 met inclusion criteria for final analysis. Athletes varied in classification from recreational to elite, and from Olympic to professional sports. Mean age for participants was 24.9 ± 4.5 y, with 70% of RCTs in males. We report consistent effects for FS on reaction time, mood, cardiovascular dynamics in cyclists, skeletal muscle recovery, the proinflammatory cytokine TNF-α, and postexercise NO responses. No clear effects on endurance performance, lung function, muscle force, or training adaptation were evident. Methodological quality, applying the Physiotherapy Evidence Database (PEDro) scale, ranged from 6 to a maximum of 11, with only 4 RCTs reporting effect sizes. Few negative outcomes were reported. We report various effects for FS on the athlete's physiology; the most consistent findings were on the central nervous system, cardiovascular system, proinflammatory cytokines, and skeletal muscle. We provide recommendations for future research and discuss the potential risks with FS use.

Geometric and "True" Densitometric Characteristics of Bones in Athletes with Stress Fracture and Menstrual Disturbances: A Systematic Review

BACKGROUND

Stress fractures can lead to short- and long-term consequences, impacting participation in sport and general health. Recognizing which skeletal characteristics render bones susceptible to stress fracture may aid stress-fracture prevention. Menstrual disturbances among exercising women are a known risk factor for stress fracture; therefore, assessing skeletal commonalities between women with stress fractures and women with menstrual disturbances may increase our understanding of why menstrual disturbances put athletes at greater risk for stress fracture. Three-dimensional (3D) bone imaging tools provide detailed information about volumetric bone mineral density (vBMD) and bone structure that cannot be obtained using traditional two-dimensional (2D) techniques.

OBJECTIVES

This systematic review serves to: (1) evaluate the current literature available on vBMD, bone geometry, and bone structure in exercising women with menstrual disturbances and exercising women with stress fractures, and (2) assess the common skeletal characteristics between both conditions. Our aim is to reveal bone properties beyond 2D areal BMD that may indicate increased susceptibility to stress fracture among exercising women with menstrual disturbances.

SEARCH METHODS

A search of the PubMed/Medline database was completed in May 2018.

ELIGIBILITY CRITERIA

Eligible articles included those that reported vBMD, bone geometry, or bone structure obtained from 3D imaging techniques or estimated from 2D imaging techniques. Only studies conducted in premenopausal exercising women and girls who had a stress fracture, a menstrual disturbance, or both were included.

RESULTS

Twenty-four articles met the inclusion criteria. Bone area and cortical thickness at the tibia were identified as altered both in women with menstrual disturbances and in women with stress fractures; however, there was inconsistency in the results observed for all bone parameters. The majority of skeletal parameters of the lower extremities were not significantly different between exercising women with and without stress fractures and between those with and without menstrual disturbances.

DISCUSSION

Most studies were moderate or low quality based on study design, and only one article combined both conditions to explore vBMD and bone geometry in athletes with menstrual disturbances and a history of stress fracture. These findings highlight the need for more skeletal research on the intersection of these health conditions in exercising women. The lack of observed differences in skeletal parameters suggests that risk factors other than bone geometry and structure may be the primary causes of stress fracture in these women.

Perceptions of risk for stress fractures: A qualitative study of female runners with and without stress fracture histories

OBJECTIVES

To gain insight into perceived factors related to bone health and stress fracture (SF) prevention for female runners and to understand their experiences within the medical community.

DESIGN

Cohort qualitative study.

SETTING

University health system.

PARTICIPANTS

Forty female runners, 20 who had SF histories and 20 age-and-running-distance matched women without SF.

MAIN OUTCOME MEASURES

Women participated in audiotaped qualitative semi-structured interviews. For women with a SF history, questions sought their perspectives on factors that they felt contributed to SF, experiences with the medical community, and changes made post SF. For women without a SF history, questions sought perspectives on factors felt important to perceived running-related bone health.

RESULTS

Six themes emerged; 1) Previous/Recurrent Musculoskeletal Injuries, 2) Activity Patterns and Training Regimens, 3) Nutrition, 4) Prevention and Intervention, 5) Pain, and 6) Mindset. Within these themes, between group differences are characterized by differences in knowledge and/or application of knowledge for health and wellness. Compared to women without SF, women with SF histories increased training load more quickly, had poorer nutrition, performed less cross-training, and kept running despite pain.

CONCLUSIONS

More education is needed for female runners to decrease risks for SF.

Bone Stress Injuries in Runners: a Review for Raising Interest in Stress Fractures in Korea

A bone stress injury (BSI) means that the bones cannot tolerate repeated mechanical loads, resulting in structural fatigue and local bone pain. A delay in BSI diagnosis can lead to more serious injuries, such as stress fractures that require longer treatment periods. Therefore, early detection of BSI is an essential part of management. Risk factors for BSI development include biological and biomechanical factors. Medical history and physical examination are the basics for a BSI diagnosis, and magnetic resonance imaging is helpful for confirming and grading. In this paper, the authors review the overall content of BSI and stress fractures which are common in runners. Through this review, we hope that interest in stress fractures will be raised in Korea and that active researches will be conducted.

Part II: presentation, diagnosis, classification, treatment, and prevention of stress fractures in female athletes

Objectives: Stress fractures (SFx) occur as the result of repetitive loads over short periods of time, which leads to micro-damage of the bone through cortical resorption, ultimately leading to fracture. They are a common injury in female athletes and often cause significant morbidity. The goal of this study is to review the presentation, diagnosis, classification, treatment, and prevention of SFx in female athletes.Results: A thorough history, physical exam, and appropriate imaging can facilitate early diagnosis of stress fracture (SFx) and faster resolution of symptoms with more conservative management. The female athlete triad is an especially important factor that contributes to the increased risk of SFx in females. The continuum of stress injuries ranges from mild microfailure to complete fracture, which has resulted in the development of newer grading schemas through MRI and radiographic findings. Stress fractures are also classified as low- or high-risk according to anatomic location, as blood supply and applied forces at different locations affect the likelihood of fracture propagation, displacement, delayed union, or non-union.Conclusions: The ability to screen for at-risk athletes is paramount in preventing SFx. Recognition and prompt treatment of the female athlete triad requires a multidisciplinary approach in order to restore energy balance, correct menstrual irregularities, and improve bone health. This review provides a basis for understanding how to identify and treat stress fractures, which may allow treating physicians to diagnose this condition earlier and minimize any associated morbidity.

Part I: epidemiology and risk factors for stress fractures in female athletes

Objectives: Stress fractures (SFx) are a common athletic injury, occurring in up to 40% of athletes at some point in their career. These injuries can cause pain, permanent disability, financial burden, and loss of playing time. This review presents updated epidemiology and comprehensive analysis of risk factors for stress fractures, especially as it pertains to female athletes.Results: Stress fractures (SFx) account for up to 10% of all orthopedic injuries and up to 20% of injuries seen in sports medicine clinics, with an incidence among female athletes as high as 13%. Lower extremity SFx represent 80-95% of SFx, and the increased popularity of endurance running has contributed to the tibia (49% prevalence) replacing the metatarsals (9%) as the most common location for lower extremity SFx. Studies have demonstrated that 50% of peak bone mass is acquired during adolescence, a 'peak time' for eating disorder and female athlete triad development; furthermore, catch-up growth cannot be expected in athletes with diminished bone growth in this critical period. The female athlete triad (low energy availability with or without disordered eating, menstrual dysfunction, and low bone mineral density) are well-known risk factors for SFx; the risk of SFx for female athletes presenting with a single aspect of the triad is 15-20%, and this risk increases to 30-50% for female athletes presenting with multiple aspects of the triad.Conclusion: This review provides a basis for how to identify populations at greatest risk for SFx. Prompt recognition of the intrinsic and extrinsic risk factors for SFx in female athletes is imperative to early diagnosis and to develop targeted strategies to prevent SFx occurrence or recurrence.

An Investigation of Habitual Dietary Supplement Use Among 557 NCAA Division I Athletes

Background: Supplements may expose athletes to dangerous ingredients, banned substances, toxins or contaminants; however, few investigations assess use among collegiate athletes in the U.S.Objective: This cross-sectional study evaluated habitual dietary supplement intake, defined use ≥2 days/week over the past year, in NCAA Division I athletes.Methods: Male and female members of a NCAA Division I team, at two universities in southern California completed a 13-item survey. Among 705 eligible participants, 596 submitted surveys (84.5% response rate), 557 surveys included complete data. Chi-square (χ²) analyses evaluated differences among athletes based on sex, weight status, year in college, and sport-type. Independent t-test or ANOVA evaluated mean differences for continuous variables.Results: A total of 45.2% athletes (n = 252) reported taking supplements (≥2 days/week over the past year). Vitamin/minerals (25.5%, n = 142), protein/amino acids (24.6%, n = 137) were used most frequently. Male, vs female athletes, took more supplements overall (1.2 ± 0.1 vs 0.8 ± 0.1, p = 0.004) and indicated higher use of protein/amino acid products (34.2% vs 13.5%, p < 0.005), whereas, females reported higher use of vitamin/minerals (30.5% vs 21.1%, p < 0.05). Higher supplement use was also reported by athletes with BMI ≥ 30.0 kg/m² (vs <30 kg/m², 1.9 ± 0.3 vs 1.0 ± 0.1, p = 0.02), and athletes in ≥ third college year (vs first or second year, 1.2 ± 0.1 vs 0.9 ± 0.1, p = 0.03).Conclusions: Nearly half of NCAA athletes reported habitual supplements use, with significant variation in patterns based on sex, sport-type, year in college, and weight status.

Bone mineral density, energy availability, and dietary restraint in collegiate cross-country runners and non-running controls

PURPOSE

Weight-bearing activities such as running have been shown to be osteogenic. However, investigations have also shown that running may lead to site-specific deficiencies in bone mineral density (BMD) as well as overall low BMD. The purpose of this investigation was to evaluate and compare the BMD of female and male collegiate cross-country runners with non-running controls. In addition, energy availability and disordered eating attitudes and behaviors were assessed.

METHODS

BMD of 60 collegiate cross-country runners and 47 BMI and age-matched non-running controls were measured via DXA scans. Participants completed a Block 2014 Food Frequency Questionnaire and Eating Disorder Examination Questionnaire.

RESULTS

Controlling for fat-free mass (FFM), male runners showed greater BMD at the femoral neck (0.934 ± 0.029 vs. 0.866 ± 0.028 g cm2, p < 0.05), total hip (1.119 ± 0.023 vs. 1.038 ± 0.021 g cm2, p < 0.05), and whole body (1.119 ± 0.023 vs. 1.038 ± 0.021 g cm2, p < 0.05) than male controls. The female runners had greater whole-body BMD than female controls (1.143 ± 0.018 vs. 1.087 ± 0.022 g cm2, p < 0.05). Runners scored significantly higher than controls in dietary restraint (1.134 ± 1.24 vs. 0.451 ± 0.75, p < 0.05), male runners were significantly higher than male controls in eating concern (1.344 ± 1.08 vs. 0.113 ± 0.27, p < 0.05) and female runners were significantly higher than male runners in shape concern (1.056 ± 1.27 vs. 0.242 ± 0.31, p < 0.05). Forty-two percent of the male runners and 29% of female runners had an energy availability of less than 30 kcals kg-1FFM.

CONCLUSION

It appears that distance running has beneficial effects on whole-body BMD and site-specific areas. Further research is warranted to further clarify the health effects of eating behaviors and EA of distance runners.

Risk factors of stress fractures due to the female athlete triad: Differences in teens and twenties

BACKGROUND

The female athlete triad (Triad), defined by the American College of Sports Medicine as low energy availability (LEA) with or without disordered eating, menstrual dysfunction, and low bone mineral density (BMD), is associated with stress fractures and athletes aged 16-17 years are most susceptible.

PURPOSE

To examine whether the Triad increases the risk of stress fractures, athletes were assigned to a "teenage" group and a "20s" group.

METHODS

This prospective study enrolled 390 elite female athletes and was conducted from 2012 to 2016 at Japan Institute of Sports Sciences. Blood concentrations of various hormones were examined, and BMD was measured at the lumbar spine and throughout the whole body using dual-energy X-ray absorptiometry. LEA was defined as body weight ≤85% of the ideal body weight for teenage athletes, or BMI ≤17.5 for athletes in their 20s. Low BMD was defined as a BMD Z-score of <-1.0 in the lumbar spine and the whole body.

RESULTS

Among 390 athletes enrolled, 36 developed new stress fractures within 3 months of registration. The risk for stress fractures due to the Triad in teenage athletes was higher than for athletes in their 20s. In teenage female athletes, secondary amenorrhea, low BMD for the whole body, and a low ratio of actual body weight to ideal body weight increased the risk for stress fractures by 12.9 times, 4.5 times, and 1.1 times, respectively.

CONCLUSION

To prevent stress fractures in female athletes with the Triad, age of athletes should be taken into consideration.

Association of catastrophic condylar fracture with bony changes of the third metacarpal bone identified by use of standing magnetic resonance imaging in forelimbs from cadavers of Thoroughbred racehorses in the United States

OBJECTIVE To compare bony changes of the third metacarpal bone (MC3) of Thoroughbred racehorse cadavers with (cases) or without (controls) catastrophic condylar fracture by use of standing MRI. SAMPLE 140 forelimbs from 26 case horses (both forelimbs) and 88 control horses (single forelimb). PROCEDURES Bone marrow lesions (BMLs), identified as a decrease in T1-weighted (T1W) signal and increases in T2*-weighted (T2*W) and short tau inversion recovery (STIR) signals, and dense bone volume percentage (DBVP), identified as decreases in T1W, T2*W, and STIR signals, in the distopalmar aspect of MC3 were recorded. Logistic regression was used to compare fractured and nonfractured limbs of cases and fractured limbs of cases with randomly selected limbs of controls. RESULTS Among cases, fractured limbs were significantly more likely to have BMLs (26/26 [100%]) than were nonfractured limbs (7/26 [27%]). Fractured limbs of cases were significantly more likely to have BMLs (26/26 [100%]) than were limbs of controls (6/88 [7%]). Among cases, there was no significant difference in DBVP between fractured and nonfractured limbs in lateral (26% vs 21%, respectively) or medial (25% vs 20%, respectively) condyles. However, DBVP was significantly greater in fractured limbs of cases than in limbs of controls for lateral (26% vs 16%, respectively) and medial (25% vs 18%, respectively) condyles. CONCLUSIONS AND CLINICAL RELEVANCE Standing MRI revealed a significantly greater degree of bone change in racehorses with condylar fracture when comparing fractured and nonfractured limbs of case horses and fractured limbs of case horses with randomly selected limbs of control horses.

Vitamin D Supplementation and Physical Activity of Young Soccer Players during High-Intensity Training

The aim of this study was to confirm that vitamin D supplementation of young soccer players during eight-week high-intensity training would have a significant effect on their motion activity. The subjects were divided into two groups: the experimental one, which was supplemented with vitamin D (SG, n = 20), and the placebo group (PG, n = 16), which was not supplemented with vitamin D. All the players were subjected to the same soccer training, described as High-Intensity Interval Training (HIIT). The data of the vitamin D status, time motion parameters and heart rate were collected just before and after the intervention. A significant increase in 25(OH)D concentration (119%) was observed in the supplemented group, while the non-supplemented group showed a decrease of 8.4%. Based on the obtained results, it was found that physical activity indicators in the players were significantly improved during small-sided games at the last stage of the experiment. However, taking into account the effect of supplementation with vitamin D, there were no statistically significant differences between the placebo and the supplemented groups; thus, the effect size of the conducted experiment was trivial.

Bone Scintigraphy: A Review of Technical Aspects and Applications in Orthopedic Surgery

Due to its high sensitivity, low cost, accessibility, and ease of use, bone scintigraphy is used in orthopedic surgery for the diagnosis and management of varied pathology. It is commonly used for insufficiency fractures, metastatic neoplasia, staging and surveillance of sarcoma, and nonaccidental trauma. It augments diagnoses, including stress or occult fractures, musculoskeletal neoplasia or infection, and chronic regional pain syndrome, in patients presenting with normal results on radiographs. Bone scan images are resistant to metal-based implant artifact, allowing effective evaluation of failed total joint prostheses. Bone scintigraphy remains an underused tool in the evaluation and management of orthopedic patients. [Orthopedics. 2019; 42(1):e14-e24.].