Return to sport following low-risk and high-risk bone stress injuries: a systematic review and meta-analysis

Training with reduced carbohydrate availability affects markers of bone resorption and formation in male academy soccer players from the English Premier League

PURPOSE

To test the hypothesis that training with reduced carbohydrate (CHO) availability increases bone resorption in adolescent soccer players.

METHODS

In a randomised crossover design, ten male players (age: 17.4 ± 0.8 years) from an English Premier League academy completed an acute 90-min field-based training session (occurring between 10:30-12:00) in conditions of high (TRAIN HIGH; 1.5 g.kg-1, 60 g, 1.5 g.kg-1 and 1.5 g.kg-1 consumed at 08:00, during training, 12:30 and 13:30, respectively) or low CHO availability (TRAIN LOW; 0 g.kg-1). Participants also completed a non-exercise trial (REST) under identical dietary conditions to TRAIN LOW. Venous blood samples were obtained at 08:30, 10:30, 12:30 and 14:30 for assessment of bone resorption (βCTX), bone formation (PINP) and calcium metabolism (PTH and ACa).

RESULTS

External training load did not differ (all P > 0.05) between TRAIN HIGH and TRAIN LOW, as evident for total distance (5.6 ± 0.8; 5.5 ± 0.1 km), average speed (81 ± 9; 85 ± 12 m.min-1) and high-speed running (350 ± 239; 270 ± 89 m). Area under the curve for both βCTX and PINP was significantly greater (P < 0.01 and P = 0.03) in TRAIN LOW versus TRAIN HIGH, whilst no differences in PTH or ACa (P = 0.11 and P = 0.89) were observed between all three trials.

CONCLUSION

CHO restriction before, during and after an acute soccer training session increased bone (re)modelling markers in academy players. Despite acute anabolic effects of bone formation, the long-term consequence of bone resorption may impair skeletal development and increase injury risk during growth and maturation.

Bone stress injuries in athletics (track and field) championships: findings from a prospective injury surveillance conducted across 24 international championships with 29,147 registered athletes

BACKGROUND

Athletics (track and field) athletes are prone to develop bone stress injuries (BSIs) but epidemiological data on BSIs from top-level sports events are scarce.

OBJECTIVE

To describe the incidence and characteristics of BSIs during 24 international athletics championships held from 2007 to 2023.

METHODS

BSI-related data were prospectively collected during 24 international athletics championships, including the Olympic Games (n = 3), World Outdoor Championships (n = 4), European Outdoor Championships (n = 6), World Indoor Championships (n = 3) and European Indoor Championships (n = 8). Descriptive and comparative statistics were used to assess the epidemiological characteristics of BSIs.

RESULTS

BSIs accounted for 1.5% of all reported injuries (n = 36; 1.2 per 1000 registered athletes (95%CI 0.8 to 1.6)). No significant difference of BSI incidence was detected between female (2.0 per 1000 athletes (95%CI: 0.9 to 2.3)) and male athletes (0.9 per 1000 athletes (95%CI: 0.4 to 1.4)) (relative risk (RR) = 1.73, 95%CI: 0.88 to 3.40). BSI incidence was significantly higher during outdoor championships (1.6 per 1000 registered athletes (95%CI: 1.0 to 2.1)) as compared to indoor championships (0.2 per 1000 registered athletes (95%CI: 0.0 to 0.5)) (RR = 10.4, 95%CI: 1.43 to 76.0). Most BSIs were sustained in the foot (n = 50%) or leg (n = 33%). BSIs were reported in athletes participating in endurance disciplines (52.8%) or in explosive disciplines (47.2%).

CONCLUSIONS

BSIs represent a small portion of injuries sustained during international athletics championships. Collective results suggest that injury rates are higher in outdoor competitions as compared to indoor competitions. The most common injury locations comprise the foot and leg.

CLINICAL TRIAL NUMBER

Not applicable.

Criteria and Guidelines for Returning to Running Following a Tibial Bone Stress Injury: A Scoping Review

Tibial bone stress injuries (BSIs) are common among long-distance runners. They have a high recurrence rate, and complexity emerges in the wider management and successful return to running. Following a tibial BSI, a critical component of complete rehabilitation is the successful return to running, and there is a lack of consistency or strong evidence to guide this process. The objectives of this review were to outline the criteria used in clinical decision-making prior to resuming running, and to establish evidence-based guidelines for the return to running process following a tibial BSI. Electronic databases including MEDLINE, CINAHL, Scopus, SPORTDiscus and AMED were searched for studies that stated criteria or provided guidelines on the objectives above. Fifty studies met the inclusion criteria and were included. Thirty-nine were reviews or clinical commentaries, three were retrospective cohort studies, two were randomised controlled trials, two were pilot studies, one was a prospective observational study, and three were case studies. Therefore, the recommendations that have been surmised are based on level IV evidence. Decisions on when an athlete should return to running should be shared between clinicians, coaches and the athlete. There are five important components to address prior to introducing running, which are: the resolution of bony tenderness, pain-free walking, evidence of radiological healing in high-risk BSIs, strength, functional and loading tests, and the identification of contributing factors. Effective return to running planning should address the athlete's risk profile and manage the risk by balancing the athlete's interests and reinjury prevention. An individualised graduated return to running programme should be initiated, often starting with walk-run intervals, progressing running distance ahead of speed and intensity, with symptom provocation a key consideration. Contributing factors to the initial injury should be addressed throughout the return to run process.

Sex differences in body composition and shock attenuation during running

Running-related impact shock is absorbed via biological tissue deformation. Given known sex differences in body composition, shock attenuation may also differ between sexes thereby influencing sex-specific running-related injury risk. This study examined sex differences in body composition and shock attenuation during running. Seventeen female (mean ± 1SD age: 34.7 ± 16.1) and twenty-one male runners (age: 29.0 ± 13.8) ran overground as inertial measurement units with triaxial accelerometers measured impact shock at the distal tibia and low-back. Frequency-domain axial and resultant shock attenuation were calculated between the low-back relative to the tibia using a transfer function of the power spectral density within 9-20, 21-35, and 36-50 Hz. Bone mineral density and content, fat and lean mass were measured in the lower extremity and pelvis/gynoid regions using dual x-ray absorptiometry. The association between sex and shock attenuation was tested using age-adjusted linear regression models, adjusted and unadjusted for body composition as a post-hoc analysis (α = 0.05). Body composition variables normalized to body mass were compared between sexes using independent samples t-tests (α = 0.05). Body composition differed between sexes (p-range: <0.001-0.01, Cohen's d range: 0.17-2.41). Before adjusting for body composition, sex was not significantly associated with axial or resultant shock attenuation (p > 0.05), but adjusting for select body composition variables like lower extremity lean and bone mass revealed greater attenuation in females than males (β-range: -124.76 to -46.42, negative indicates greater attenuation; p-range = 0.004-0.04). Sex may not influence shock attenuation during running, but body composition must be accounted for to better understand this association and consequently sex-specific tissue capacities relative to applied loads.

Influence of Body Weight Measurement Frequency on the Bone Health of Female Athletes

Purpose: Athletes struggle with bone stress injuries despite the many risk factors reported in previous studies. However, the relationship between body weight measurement frequency and risk of stress fractures has yet to be investigated. Thus, the purpose of this study is to seek the link between body weight measurement frequency and the occurrence of stress fractures. Method: This cross-sectional study included female athletes who were requested to fill out an anonymous online survey regarding their personal background, including the history of amenorrhea and stress fractures. In addition, the frequency at which they measured their body weight and composition and whether they had to report the same to their coaches and seniors were asked. Results: A total of 172 collegiate female athletes for 28 different types of sports participated in this study. Among the included athletes, 35.7% had a history of amenorrhea, whereas 29.7% had a history of stress fractures. A total of 57.0% of the athletes answered that in their team, they measure their body weight on a regular basis, and 33.1% of the athletes answered that they reported the data to their coaches. Logistic regression analysis revealed that those who measured their body weight at least once a day had a higher risk of sustaining stress fractures than did those who measured their body weight less than once a day (OR = 2.36, 95% CI 1.06-5.27, p = .04). Conclusion: Body weight measurement frequency was associated with the risk of stress fractures in female collegiate athletes.

Relative Energy Deficiency in Sport (RED-S) and Goldman's Dilemma: A Case Report in 42 Year-Old Woman Endurance Athlete

Relative Energy Deficiency in Sport (RED-S) defines insufficient calorie intake for the physiological and athletic functions of the athlete, and accordingly deterioration in the musculoskeletal, hormonal, cardiovascular and immune systems. Herein, we present a 42-year-old female long-distance runner with multiple pelvic stress fractures who didn't complete her prescribed treatment program and wanted to keep running despite being aware of the associated pain and risks. The Goldman dilemma refers to the unsettling reality that a significant number of professional athletes may contemplate sacrificing their lives in order to achieve Olympic glory. This disregard for the numerous challenges stemming from an obsession with success is equally applicable to the amateur athlete depicted in this case. Our patient's fractures were examined in relation to RED-S and managed through conservative treatment methods. The RED-S and Goldman dilemma should be kept in mind not only in professional but also in semi-professional, and amateur athletes.

Epidemiology of bone injuries in elite athletics: A prospective 9-year cohort study

OBJECTIVES

To describe bone injury patterns in elite track and field athletes. To investigate relationships between bone injury and athlete characteristics to inform future injury prevention strategies.

DESIGN

Descriptive epidemiology study.

SETTING

Elite athletics training centres across the United Kingdom and internationally, observed between 2012 and 2020.

PARTICIPANTS

207 Olympic programme senior track and field athletes.

MAIN OUTCOME MEASURES

Injury number, Incidence, Severity, Burden, Time Loss.

RESULTS

There were 78 fractures during the study period. Gradual repetitive bone injuries were the most common type of injury mode. The foot, pelvis and the lumbar spine were the regions with the highest number of bone stress injuries. Stress fractures had a higher burden overall compared to stress reactions. Average return to full training was 67.4 days (±73.1) for stress reactions and 199 (±205.2) days for stress fractures. There was no relationship between bone injury type and age, sex, ethnicity, side dominance or event group.

CONCLUSION

Bone stress injuries in athletics have a high severity and burden warranting continued efforts to prevent their occurrence and optimize management. Age, sex, ethnicity, side dominance and event region do not have any relationship with bone injury occurrence and are therefore unlikely to increase risk in this cohort.

[Stress fractures in the military context]

BACKGROUND

Soldiers, especially as recruits, are exposed to significantly elevated stress patterns of the foot due to occupation-related marching and excessive running. This can lead to military-specific stress fractures of the metatarsals, i.e., marching fractures. The treatment and prevention of stress fractures are of particular importance in the military context due to the impact on operational capability and treatment costs. A uniform classification of these fractures does not yet exist.

OBJECTIVE

Review of stress fractures in the military setting with presentation of the incidence, risk factors, classification, treatment and prevention possibilities.

MATERIAL AND METHODS

A PubMed®-based review of the current literature on stress fractures in the military context was conducted and the results were discussed with a focus on specific military medical treatment options.

RESULTS

There are several possibilities to classify stress fractures, the most well-known being a 4-level magnetic resonance imaging (MRI)-based classification. Prevention and treatment possibilities are multifaceted but so far insufficiently validated.

CONCLUSION

Military-specific stress fractures should be grouped according to a 4-level and MRI-based classification. The treatment options include both conservative and surgical measures and should be implemented taking the patient's individual requirements into account. Preventive measures play a key role in the military context. They include the adaptation of screening tools, training and equipment and require continuous evaluation and development.

Bone Stress Injuries in Runners Using Carbon Fiber Plate Footwear

The introduction of carbon fiber plate footwear has led to performance benefits in runners. The mechanism for these changes in running economy includes altered biomechanics of the foot and ankle. The association of this footwear with injuries has been a topic of debate clinically, but not described in the literature. In this Current Opinion article, illustrated by a case series of five navicular bone stress injuries in highly competitive running athletes, we discuss the development of running-related injuries in association with the use of carbon fiber plate footwear. While the performance benefits of this footwear are considerable, sports medicine providers should consider injuries possibly related to altered biomechanical demands affecting athletes who use carbon fiber plate footwear. Given the introduction of carbon fiber plate footwear into athletics and other endurance sports, strategies may be required to reduce risk of injury due to altered foot and ankle mechanics. This article is intended (1) to raise awareness on possible health concerns around the use of carbon fiber plate footwear, (2) to suggest a slow gradual transition from habitual to carbon fiber plate footwear, and (3) to foster medical research related to carbon fiber plate technology and injuries.

Outcomes Using Focused Shockwave for Treatment of Bone Stress Injury in Runners

Bone stress injury (BSI) is a common overuse injury that can result in prolonged time away from sport. Limited studies have characterized the use of extracorporeal shockwave therapy (ESWT) for the treatment of BSI. The purpose of this study was to describe the use of ESWT for the management of BSI in runners. A retrospective chart review was performed to identify eligible patients in a single physician's clinic from 1 August 2018 to 30 September 2022. BSI was identified in 40 runners with 41 injuries (28 females; average age and standard deviation: 30 ± 13 years; average pre-injury training 72 ± 40 km per week). Overall, 63% (n = 26) met the criteria for moderate- or high-risk Female or Male Athlete Triad categories. Runners started ESWT at a median of 36 days (IQR 11 to 95 days; range 3 days to 8 years) from BSI diagnosis. On average, each received 5 ± 2 total focused ESWT treatments. Those with acute BSI (ESWT started <3 months from BSI diagnosis) had an average return to run at 12.0 ± 7.5 weeks, while patients with delayed union (>3 months, n = 3) or non-union (>6 months, n = 9) had longer time for return to running (19.8 ± 14.8 weeks, p = 0.032). All runners returned to pain-free running after ESWT except one runner with non-union of grade 4 navicular BSI who opted for surgery. No complications were observed with ESWT. These findings suggest that focused ESWT may be a safe treatment for the management of BSI in runners.

"Biofeedback-based return to sport": individualization through objective assessments

Elite athletes are regularly exposed to high and repetitive mechanical stresses and impacts, resulting in high injury rates. The consequences of injury can range from time lost from training and competition to chronic physical and psychological burden, with no guarantee that the athlete will return to preinjury levels of sport activity and performance. Prominent predictors include load management and previous injury, highlighting the importance of the postinjury period for effective return to sport (RTS). Currently, there is conflicting information on how to choose and assess the best reentry strategy. Treating RTS as a continuum, with controlled progression of training load and complexity, seems to provide benefits in this process. Furthermore, objectivity has been identified as a critical factor in improving the effectiveness of RTS. We propose that assessments derived from biomechanical measurements in functional settings can provide the objectivity needed for regular biofeedback cycles. These cycles should aim to identify weaknesses, customize the load, and inform on the status of RTS progress. This approach emphasizes individualization as the primary determinant of RTS and provides a solid foundation for achieving it.