Sport Specialization and Low Bone Mineral Density in Female High School Distance Runners

Cross-sectional size, shape, and estimated strength of the tibia, fibula and second metatarsal in female collegiate-level cross-country runners and soccer players

Bone stress injuries (BSIs) frequently occur in the leg and foot long bones of female distance runners. A potential means of preventing BSIs is to participate in multidirectional sports when younger to build a more robust skeleton. The current cross-sectional study compared differences in tibia, fibula, and second metatarsal diaphysis size, shape, and strength between female collegiate-level athletes specialized in cross-country running (RUN, n = 16) and soccer (SOC, n = 16). Assessments were performed using high-resolution peripheral quantitative computed tomography and outcomes corrected for measures at the radius diaphysis to control for selection bias and systemic differences between groups. The tibia in SOC had a 7.5 % larger total area than RUN, with a 29.4 % greater minimum second moment of area (IMIN) and 8.2 % greater estimated failure load (all p ≤ 0.02). Tibial values in SOC exceeded reference data indicating positive adaptation. In contrast, values in RUN were similar to reference data suggesting running induced limited tibial adaptation. RUN did have a larger ratio between their maximum second moment of area (IMAX) and IMIN than both SOC and reference values. This suggests the unidirectional loading associated with running altered tibial shape with material distributed more in the anteroposterior (IMAX) direction as opposed to the mediolateral (IMIN) direction. Comparatively, SOC had a similar IMAX/IMIN ratio to reference data suggesting the larger tibia in SOC resulted from multiplane adaptation. In addition to enhanced size and strength of their tibia, SOC had enhanced structure and strength of their fibula and second metatarsal. At both sites, polar moment of inertia was approximately 25 % larger in SOC compared to RUN (all p = 0.03). These data support calls for young female athletes to delay specialization in running and participate in multidirectional sports, like soccer, to build a more robust skeleton that is potentially more protected against BSIs.

Menstrual Dysfunction in Adolescent Female Athletes

Despite the benefits of exercise on mental and physical health, excessive training loads can lead to health problems in the long term, including a wide spectrum of menstrual dysfunction (MD). This narrative review aims to analyze the relationship between physical exercise and MD in adolescent female athletes to support regular menstrual health monitoring and promote educational programs on reproductive risks. When dealing with MD in young athletes, several factors entangled with maturation of the hypothalamus-pituitary-ovarian axis should be considered. Firstly, some disciplines seem to have a higher prevalence of MD due to the high loads of training regimes and the early introduction of athletes to a competitive career. Moreover, low energy intake and a low body mass index appear to exacerbate existing MD. Lastly, disordered eating behaviors and psychological stress can contribute to MD in female athletes. The type of sport, influencing the intensity and duration of exercise, as well as individual psycho-physiological and environmental factors, may influence the role of physical activity in the manifestation of MD. Early recognition and management of MD, along with collaboration between sports organizations and health professionals, are crucial to minimize risks, ensure proper nutrition, and balance training with recovery. Keeping an open discussion on the topic may prospectively improve awareness, early diagnosis, and treatment strategies, as well as reduce injury risk and enhance sports performance.

Epidemiology of injuries in united states high school track and field jumping events from 2008 - 2019

OBJECTIVES

Reports of injury characteristics of high school track and field athletes participating in jumping events in the United States are limited. In this descriptive epidemiological study, we report injury rates and patterns in these athletes.

METHODS

Injuries and athletic exposures (AE) from the National High School Sports Related Injury Surveillance System, and High School Reporting Information Online (RIO) from 2008-2019 were analyzed. Jumping events included high jump, long jump, triple jump, and pole vault. Injury rate ratios (IRR) and injury proportion ratios (IPR) were examined by sex.

RESULTS

A total of 727 injuries related to jumping events during 5,486,279 AEs occurred with the highest frequency at the thigh (20.3%) followed by the ankle (18.2%), knee (16.1%), and lower leg (11.0%). The most common types of injuries were muscle strain (29.0%) and ligament sprain (21.2%). Most athletes returned to sport within 1 week (43.1%, n = 312) or 3 weeks (34.7%, n = 243). Few jumping-related injuries resulted in surgery (4.9%, n = 35) or medical disqualification (4.4%, n = 31). The jumping-related injury rate was 1.33 injuries/10,000 AEs from 2008 to 2019. The rate of jumping-related injuries was higher in competition than in practice (IRR = 2.63, 95% confidence interval [CI]: 2.25-3.06). Injury rates were significantly higher in practice for female athletes than for males (IRR = 1.51, 95% CI: 1.23-1.86). Compared to male athletes, female athletes sustained a higher proportion of ankle injuries (IPR = 1.63, 95% CI: 1.15-2.32) and ligament sprains (IPR = 1.55, 95% CI: 1.16-2.09).

CONCLUSIONS

This study describes injury characteristics of high school track and field jumping athletes from 2008 to 2019. We found an overall injury rate of 1.33 injuries per 10,000 AEs. Higher overall rates of jumping-related injuries occurred during competitions than in practice, and female athletes displayed a significantly higher rate of injuries during practices compared to male athletes.

Epidemiology of injuries in U.S. high school track and field throwing events from 2008 to 2019

BACKGROUND

Injury characteristics of high school track and field throwing athletes in the United States are not well studied. Understanding epidemiology of injuries is important to identify treatment and prevention strategies.

OBJECTIVE

To describe injury rates and patterns in U.S. high school track and field throwing events from a longitudinal national sports injury surveillance system.

DESIGN

Descriptive epidemiology study.

SETTING

Data were provided by the National High School Sports Related Injury Surveillance System, High School RIO (Reporting Information Online).

METHODS

Athletic trainers reported injury and exposure data through the High School RIO website on a weekly basis. An athlete exposure (AE) was defined as one athlete participating in one school-sanctioned practice or competition. Throwing events of discus, shot put, and javelin were analyzed in this study.

MAIN OUTCOME MEASURES

Injury rate, rate ratios (RR), injury proportion ratios (IPR).

PARTICIPANTS

U.S. high school athletes.

RESULTS

A total of 267 track and field throwing injuries occurred during 5,486,279 AEs. Overall, the rate of injuries in competition was higher than in practice (RR 1.35, 95% confidence interval [CI] 1.01-1.80). In practice, the rate of injuries was higher for girls than boys (RR 1.53, 95% CI 1.12-2.08). The most frequently injured body part was the shoulder (21.7%), followed by the ankle (16.5%) and knee (12.0%). The most common types of injury were muscle strains (26.14%) and ligament sprains (25%). Recurrent injuries accounted for a higher proportion of chronic injuries compared to new injuries (IPR 1.85, 95% CI 1.16-2.97).

CONCLUSION

This study described injury characteristics of high school track and field throwing athletes from 2008 to 2019. Based on our results, injury prevention may be particularly important for female throwers with prior injury.

Short-term effects and long-term changes of FUEL-a digital sports nutrition intervention on REDs related symptoms in female athletes

Female endurance athletes are at high risk for developing Relative Energy Deficiency in Sport (REDs), resulting in symptoms such as menstrual dysfunction and gastrointestinal (GI) problems. The primary aim of this study was to investigate effects of the FUEL (Food and nUtrition for Endurance athletes-a Learning program) intervention consisting of weekly online lectures combined with individual athlete-centered nutrition counseling every other week for sixteen weeks on REDs related symptoms in female endurance athletes at risk of low energy availability [Low Energy Availability in Females Questionnaire (LEAF-Q) score ≥8]. Female endurance athletes from Norway (n = 60), Sweden (n = 84), Ireland (n = 17), and Germany (n = 47) were recruited. Fifty athletes with risk of REDs (LEAF-Q score ≥8) and with low risk of eating disorders [Eating Disorder Examination Questionnaire (EDE-Q) global score <2.5], with no use of hormonal contraceptives and no chronic diseases, were allocated to either the FUEL intervention (n = 32) (FUEL) or a sixteen-week control period (n = 18) (CON). All but one completed FUEL and n = 15 completed CON. While no evidence for difference in change in LEAF-Q total or subscale scores between groups was detected post-intervention (BFincl < 1), the 6- and 12-months follow-up revealed strong evidence for improved LEAF-Q total (BFincl = 123) and menstrual score (BFincl = 840) and weak evidence for improved GI-score (BFincl = 2.3) among FUEL athletes. In addition, differences in change between groups was found for EDE-Q global score post-intervention (BFincl = 1.9). The reduction in EDE-Q score remained at 6- and 12- months follow-up among FUEL athletes. Therefore, the FUEL intervention may improve REDs related symptoms in female endurance athletes.

Clinical Trial Registration

www.clinicaltrials.gov (NCT04959565).

The Role of Oxidative Stress in Multiple Exercise-Regulated Bone Homeostasis

Bone is a tissue that is active throughout the lifespan, and its physiological activities, such as growth, development, absorption, and formation, are always ongoing. All types of stimulation that occur in sports play an important role in regulating the physiological activities of bone. Here, we track the latest research progress locally and abroad, summarize the recent, relevant research results, and systematically summarize the effects of different types of exercise on bone mass, bone strength and bone metabolism. We found that different types of exercise have different effects on bone health due to their unique technical characteristics. Oxidative stress is an important mechanism mediating the exercise regulation of bone homeostasis. Excessive high-intensity exercise does not benefit bone health but induces a high level of oxidative stress in the body, which has a negative impact on bone tissue. Regular moderate exercise can improve the body's antioxidant defense ability, inhibit an excessive oxidative stress response, promote the positive balance of bone metabolism, delay age-related bone loss and deterioration of bone microstructures and have a prevention and treatment effect on osteoporosis caused by many factors. Based on the above findings, we provide evidence for the role of exercise in the prevention and treatment of bone diseases. This study provides a systematic basis for clinicians and professionals to reasonably formulate exercise prescriptions and provides exercise guidance for patients and the general public. This study also provides a reference for follow-up research.

Bone health in Norwegian female elite runners: a cross-sectional, controlled study

Objective

The primary objective was to compare bone mineral density (BMD) in Norwegian female elite long-distance runners with a control group of inactive females. Secondary objectives were to identify cases of low BMD, to compare the concentration of bone turnover markers, vitamin D and symptoms of low energy availability (LEA) between the groups, and to identify possible associations between BMD and selected variables.

Methods

Fifteen runners and fifteen controls were included. Assessments included dual-energy X-ray absorptiometry measurement of BMD in the total body, lumbar spine and dual proximal femur. Blood samples included endocrine analyses and circulating bone turnover markers. The risk of LEA was assessed through a questionnaire.

Results

Runners had higher Z-scores in the dual proximal femur (1.30 (0.20 to 1.80) vs 0.20 (-0.20 to 0.80), p<0.021) and total body (1.70 (1.20 to 2.30) vs 0.90 (0.80 to 1.00), p<0.001). The lumbar spine Z-score was similar between groups (0.10 (-0.70 to 0.60) vs -0.10(-0.50 to 0.50), p=0.983). Three runners had low BMD (Z-score <-1) in the lumbar spine. Vitamin D and bone turnover markers showed no differences between the groups. Forty-seven per cent of the runners were at risk of LEA. Dual proximal femur BMD showed a positive correlation to estradiol and a negative correlation to LEA symptoms in runners.

Conclusion

Norwegian female elite runners had higher BMD Z-score in the dual proximal femur and total body compared with controls, while no difference was observed in the lumbar spine. The advantages of long-distance running on bone health seem to be site specific, and there is still a need for the prevention of LEA and menstrual disorders in this group.

Enhanced Bone Size, Microarchitecture, and Strength in Female Runners with a History of Playing Multidirectional Sports

PURPOSE

Female runners have high rates of bone stress injuries (BSIs), including stress reactions and fractures. The current study explored multidirectional sports (MDS) played when younger as a potential means of building stronger bones to reduce BSI risk in these athletes.

METHODS

Female collegiate-level cross-country runners were recruited into groups: 1) RUN, history of training and/or competing in cross-country, recreational running/jogging, swimming, and/or cycling only, and 2) RUN + MDS, additional history of training and/or competing in soccer or basketball. High-resolution peripheral quantitative computed tomography was used to assess the distal tibia, common BSI sites (diaphysis of the tibia, fibula, and second metatarsal), and high-risk BSI sites (base of the second metatarsal, navicular, and proximal diaphysis of the fifth metatarsal). Scans of the radius were used as control sites.

RESULTS

At the distal tibia, RUN + MDS ( n = 18) had enhanced cortical area (+17.1%) and thickness (+15.8%), and greater trabecular bone volume fraction (+14.6%) and thickness (+8.3%) compared with RUN ( n = 14; all P < 0.005). Failure load was 19.5% higher in RUN + MDS ( P < 0.001). The fibula diaphysis in RUN + MDS had an 11.6% greater total area and a 11.1% greater failure load (all P ≤ 0.03). At the second metatarsal diaphysis, total area in RUN + MDS was 10.4% larger with greater cortical area and thickness and 18.6% greater failure load (all P < 0.05). RUN + MDS had greater trabecular thickness at the base of the second metatarsal and navicular and greater cortical area and thickness at the proximal diaphysis of the fifth metatarsal (all P ≤ 0.02). No differences were observed at the tibial diaphysis or radius.

CONCLUSIONS

These findings support recommendations that athletes delay specialization in running and play MDS when younger to build a more robust skeleton and potentially prevent BSIs.

Preventing Bone Stress Injuries in Runners with Optimal Workload

Bone stress injuries (BSIs) occur at inopportune times to invariably interrupt training. All BSIs in runners occur due to an "error" in workload wherein the interaction between the number and magnitude of bone tissue loading cycles exceeds the ability of the tissue to resist the repetitive loads. There is not a single optimal bone workload, rather a range which is influenced by the prevailing scenario. In prepubertal athletes, optimal bone workload consists of low-repetitions of fast, high-magnitude, multidirectional loads introduced a few times per day to induce bone adaptation. Premature sports specialization should be avoided so as to develop a robust skeleton that is structurally optimized to withstand multidirectional loading. In the mature skeleton, optimal workload enables gains in running performance but minimizes bone damage accumulation by sensibly progressing training, particularly training intensity. When indicated (e.g., following repeated BSIs), attempts to reduce bone loading magnitude should be considered, such as increasing running cadence. Determining the optimal bone workload for an individual athlete to prevent and manage BSIs requires consistent monitoring. In the future, it may be possible to clinically determine bone loads at the tissue level to facilitate workload progressions and prescriptions.

Physical Activity, Menstrual History, and Bone Microarchitecture in Female Athletes with Multiple Bone Stress Injuries

Bone stress injuries (BSIs) occur in up to 20% of runners and military recruits and those with a history of BSI have a 5-fold higher risk for a subsequent BSI. Yet, little is known about prior training, menstrual status and bone structure in runners who experience multiple BSIs.

PURPOSE

To determine differences in health and physical activity history, bone density, microarchitecture, and strength among female athletes with a history of multiple BSI, athletes with ≤1 BSI, and non-athletes.

METHODS

We enrolled 101 women (ages 18-32 years) for this cross-sectional study: non-athlete controls (n=17) and athletes with a history of ≥ 3 BSIs (n=21) or ≤1 BSI (n=63). We collected subjects' health and training history and measured bone microarchitecture of the distal tibia via high-resolution peripheral quantitative computed tomography (HR-pQCT) and areal bone mineral density (aBMD) of the hip and spine by dual-energy X-ray absorptiometry (DXA).

RESULTS

Groups did not differ according to age, BMI, age at menarche, aBMD, or tibial bone microarchitecture. Women with multiple BSIs had a higher prevalence of primary and secondary amenorrhea (p<0.01) compared to other groups. Total hours of physical activity in middle school were similar across groups; however, women with multiple BSIs performed more total hours of physical activity in high school (p=0.05), more hours of uniaxial loading in both middle school and high school (p=0.004, p=0.02) and a smaller proportion of multiaxial loading activity compared to other groups.

CONCLUSION

These observations suggest that participation in sports with multiaxial loading and maintaining normal menstrual status during adolescence and young adulthood may reduce the risk of multiple bone stress injuries.