Tibial Bone Geometry Is Associated With Bone Stress Injury During Military Training in Men and Women

Comparative analysis of elbow radiographic measurements in patients with supracondylar humerus fractures and healthy controls

BACKGROUND

Supracondylar humeral fractures (SCHF) are the second most common fractures in childhood and can lead to short- and long-term complications. Despite their prevalence, the anatomical factors that predispose children to SCHF remain unclear. This study aimed to determine whether there are significant morphological differences in the elbow by comparing the radiographic angular measurements of the contralateral elbows of patients with SCHF to those of patients with distal radius fractures (DRF) and a healthy control group. We sought to explore if these morphological variations contribute to the occurrence of SCHF.

AIM

To determine radiological parameters that may predispose to pediatric elbow fractures.

METHODS

Radiographs of 78 SCHF patients were analyzed for angular measurements of the contralateral elbow. Two control groups were used: 98 healthy children and 40 patients with DRF. Angular measurements included Baumann angle (BA), humeroulnar angle (HUA), humerus metaphysis-diaphysis angle (HMDA), humerus shaft-condylar angle (HSCA), and lateral capitellohumeral angle. Only BA, HUA, and HMDA were measured in the DRF group. Statistical analysis was performed to compare differences among groups.

RESULTS

Significant differences were found in elbow measurements between SCHF and control groups (P < 0.05). However, the mean values for all groups fell within the ranges described in the literature.

CONCLUSION

While statistically significant differences were found in elbow morphology between SCHF patients and controls, these differences don't translate into clinically meaningful morphological deviations.

Association of allostatic load measured by allostatic load index on physical performance and psychological responses during arduous military training

Military personnel experience decrements in physical fitness and psychological well-being during training that may be attributed to allostatic load. This investigation examined the association between allostatic load measured by the allostatic load index (ALI) and physical performance and psychological responses in personnel undergoing a 10-week training course. Thirty-one participants (14 women) provided biochemical, questionnaire (perceived stress appraisal (PSS), sleep difficulty (SD), resilience (CD-RISC-25), and Physical Fitness Test (PFT; three-mile run [3MR], pullups, Run-Row PFT score, Push-Pull PFT score, Crunches-Plank PFT score, and total PFT score)) data before and after training. ALI (0-8) was calculated using biomarker components from neuroendocrine, autonomic, and immune systems. Simple linear regression analysis assessed the association between change (Δ) in ALI and responses. Backward stepwise regression identified components associated with responses (α = 0.05). In men, ΔALI was associated with Δpullups (β = -0.88, p = 0.015), Δpush-pull PFT score (β = -2.87, p = 0.013), Δtotal PFT score (β = -3.48, p = 0.007), and ΔSD (β = -0.56, p = 0.046) with immune components explaining relationships. In women, ΔALI was associated with ΔSD (β = -1.25, p < 0.001) and ΔCD-RISC-25 (β = 2.65, p = 0.025) with no component explaining relationships. Increased ALI is associated with worsened physical performance in men and improved psychological outcomes in women, highlighting potential sex-specific responses to increased allostatic load during training.

Differences in Body Composition, Bone Density, and Tibial Microarchitecture in Division I Female Athletes Participating in Different Impact Loading Sports

Sport participation affects body composition and bone health, but the association between sport, body composition, and bone health in female athletes is complex. We compared areal bone mineral density (aBMD, DXA) and tibial volumetric bone mineral density (vBMD), geometry, microarchitecture, and estimated strength (HR-pQCT) in cross-country runners (n = 22), gymnasts (n = 23) and lacrosse players (n = 35), and investigated associations of total body lean mass (TBLM), team, and their interaction with tibial bone outcomes. Total body (TB), total hip (TH), femoral neck (FN), and lumbar spine (LS) aBMD were higher in gymnasts than runners (p < 0.001); FN and LS aBMD were higher in gymnasts than lacrosse players (p ≤ 0.045); and TB, TH, FN, and LS aBMD were higher in lacrosse players than runners (p ≤ 0.013). At the distal tibial metaphysis, total area (Tt.Ar) was higher in gymnasts than runners (p = 0.004); cortical area and thickness (Ct.Ar, Ct.Th) were higher in lacrosse players than runners (p ≤ 0.044); trabecular separation (Tb.Sp) was higher in runners than gymnasts (p = 0.031); and failure load was higher in both gymnasts and lacrosse players than runners (p ≤ 0.012). At the tibial diaphysis, Tt.Ar, Ct.Ar, cortical perimeter (Ct.Pm), and failure load were higher in gymnasts than runners (p ≤ 0.040). In multiple linear regression analyses, TBLM was significantly associated with metaphyseal failure load (ß = 0.30, p = 0.042), and diaphyseal Tt.Ar and Ct.Pm (ß = 6.17, p = 0.003; ß = 0.59, p = 0.010). Bone health can vary among different sport types and is associated with TBLM, which may be a modifiable factor to maintain or improve bone health.

Tibial Skeletal Adaptations in Male and Female Marine Corps Officer Candidates Undergoing 10 Weeks of Military Training

Military training improves tibial density, structure, and estimated strength; however, men and women may adapt differently. Most work performed in military populations has assessed changes in bone health during initial entry programs, a timeframe at the beginning of a service member's career when bones may be more adaptable to a novel mechanical stimulus. The purpose of this investigation was to examine changes in tibial volumetric bone mineral density (vBMD), structure, and estimated strength, and biomarkers of bone metabolism (P1NP, osteocalcin, TRAP5b, sclerostin) between male and female candidates measured at the start and end of United States Marine Corps Officer Candidates School (OCS), a 10-week military training program attended by older service members (~ 25 y/o) who may have previous military experience. Peripheral quantitative computed tomography (pQCT) of the tibia (n = 375) and blood draws (n = 385) were performed. Generalized linear mixed effects modeling compared changes between sexes over time. Increases in total and trabecular vBMD were observed at the 4% site in the total sample, but total and cortical vBMD decreased in female candidates at the 66% site. Periosteal circumference at the 38% and 66% sites increased in the total sample. Estimated strength increased similarly in male and female candidates at the 4% and 38% sites but only increased in male candidates at the 66% site. Concentrations of P1NP and osteocalcin increased similarly in both sexes, although sclerostin and TRAP5b decreased only in male candidates. Measures of tibial vBMD, width, and estimated strength increased following OCS consistent with adaptive bone formation.

Inflammatory and Oxidant Responses to Arduous Military Training: Associations with Stress, Sleep, and Performance

BACKGROUND

Arduous military training frequently consists of prolonged physical activity, sleep disturbance, and stress that increases musculoskeletal injury risk and performance decrements. Inflammatory and oxidative stress responses have been reported in response to arduous training, but with inconsistencies across markers and with underrepresentation of women. The purpose of the current report was to measure circulating inflammation and oxidative stress responses to military training and to correlate biomarkers with subjective measures of stress and sleep quality as well as military fitness test performance.

METHODS

Candidates undergoing the 10-wk Marine Corps Officer Candidate School (OCS; 101 men, 62 women) were monitored, with demographic and questionnaire data collected, and blood drawn before and after OCS. Blood was analyzed for six markers of inflammation and three markers of oxidative stress. Associations between biomarkers and questionnaire and fitness test performance were tested.

RESULTS

All measured inflammatory markers as well as plasma antioxidant capacity were elevated following OCS. The inflammatory increase was higher in women for several markers. Sleep disturbance and stress perception were associated with interleukin (IL)-6, IL-10, and C-reactive protein concentrations, suggesting that low sleep disturbance and stress perception were associated with low inflammatory load. In addition, those with the highest inflammation at each time point performed worse on fitness tests than those with low inflammation.

CONCLUSIONS

Following arduous military training, the circulating environment in a significant portion of officer candidates resembled chronic low-grade inflammation. This circulating inflammatory environment appeared worse with poor sleep, high stress perception, and poor fitness test performance, with utility observed for C-reactive protein, IL-6, and IL-10 as biomarkers of these responses. Because inflammation may contribute to musculoskeletal injury and performance decrements, minimizing chronic inflammation during military training should be explored.

Biomechanical and physiological biomarkers are useful indicators of military personnel readiness: a multi-institutional, multinational research collaboration

A ubiquitous problem facing military organisations is musculoskeletal injury (MSKI) risk identification. Recently, two research groups, each with their own funding, collaborated to address this problem. Combining their respective areas of expertise in biomechanics and physiological biomarkers, the group explored this problem in the laboratory and in the field. They have developed a machine learning model in a US Marine Corps (USMC) officer cadet cohort that identifies MSKI risk from a single jump test, identified a minimum inertial measurement unit sensor array to quantity jump and squat performance and have identified sex differences in overuse, lower-limb injury risk. This machine learning model was able to correctly predict lift to place within 4 kg using a testing data set and less than 1 kg in the training set of data. Such collaborative approaches are encouraged to address complicated research problems. To assemble an effective team, consider forming groups that best complement each other's areas of expertise and prioritise securing separate funding to ensure each group can act independently. By doing this, the group has assessed the suitability and feasibility of various wearable technologies, used machine learning to gain insights into USMC physiological training adaptations, and developed an understanding of MSKI risk profiles within this cohort.

Advancing Exoskeleton Development: Validation of a Robotic Surrogate to Measure Tibial Strain

Bone stress injuries are prevalent among athletes and military recruits and can significantly compromise training schedules. The development of an ankle-foot orthosis to reduce tibial load and enable a faster return to activity will require new device testing methodologies capable of capturing the contribution of muscular force on tibial strain. Thus, an actuated robotic surrogate leg was developed to explore how tibial strain changes with different ankle-foot orthosis conditions. The purpose of this work was to assess the reliability, scalability, and behavior of the surrogate. A dual actuation system consisting of a Bowden cable and a vertical load applied to the femur via a material testing system, replicated the action-reaction of the Achilles-soleus complex. Maximum and minimum principal strain, maximum shear strain, and axial strain were measured by instrumented strain gauges at five locations on the tibia. Strains were highly repeatable across tests but did not consistently match in vivo data when scaled. However, the stiffness of the ankle-foot orthosis strut did not systematically affect tibial load, which is consistent with in vivo findings. Future work will involve improving the scalability of the results to match in vivo data and using the surrogate to inform exoskeletal designs for bone stress injuries.

Fractures in Thoroughbred racing and the potential for pre-race identification of horses at risk

Risk rates for and predisposing factors to fractures occurring in Thoroughbred racing that have been published in peer reviewed journals are documented. The potential for currently available techniques to identify horses at increased risk for fracture is discussed on the bases of principles, practicalities, advantages, disadvantages and current data. All are reviewed in light of justifiable decision making and importance of fractures to horseracing's social license.

Effect of acute resistance exercise on bone turnover in young adults before and after concurrent resistance and interval training

Weight-bearing physical activity can stimulate bone adaptation. This investigation explored the effect of an acute bout of resistance exercise before and after resistance+interval training on circulating biomarkers of bone metabolism and muscle-bone crosstalk. Healthy young male and female participants (n = 21 male, 28 ± 4 years; n = 17 female, 27 ± 5 years) performed a 6 × 10 squat test (75% 1RM) before and after a 12-week resistance+interval training program. Before and after completion of the training program, blood samples were collected at rest, immediately postexercise, and 2 h postexercise. Blood samples were analyzed for βCTX, P1NP, sclerostin, osteocalcin, IGF-1, and irisin. Significant effects of acute exercise (main effect of time) were observed as increases in concentrations of IGF-1, irisin, osteocalcin, and P1NP from rest to postexercise. A sex*time interaction indicated a greater decline in βCTX concentration from rest to 2 h postexercise and a greater increase in sclerostin concentration from rest to immediately postexercise in male compared with female participants. Sex differences (main effect of sex) were also observed for irisin and P1NP concentrations. In summary, changes in concentrations of biochemical markers of bone metabolism and muscle-bone crosstalk were observed in males and females after an acute bout of resistance exercise and following 12 weeks of resistance+interval training.

A hierarchical clustering approach for examining the relationship between pelvis-proximal femur geometry and bone stress injury in runners

Bone stress injury (BSI) risk in runners is multifactorial and not well understood. Unsupervised machine learning approaches can potentially elucidate risk factors for BSI by identifying groups of similar runners within a population which differ in BSI incidence. Here, a hierarchical clustering approach is used to identify groups of collegiate cross country runners based on 2-dimensional frontal plane pelvis and proximal femur geometry, which was extracted from dual-energy X-ray absorptiometry scans and dimensionally reduced by principal component analysis. Seven distinct groups were identified using the cluster tree, with the initial split being highly related to female-male differences. Visual inspection revealed clear differences between groups in pelvis and proximal femur geometry, and groups were found to differ in lower body BSI incidence during the subsequent academic year (Rand index = 0.53; adjusted Rand index = 0.07). Linear models showed between-cluster differences in visually identified geometric measures. Geometric measures were aggregated into a pelvis shape factor based on trends with BSI incidence, and the resulting shape factor was significantly different between clusters (p < 0.001). Lower shape factor values, corresponding with lower pelvis height and ischial span, and greater iliac span and trochanteric span, appeared to be related to increased BSI incidence. This trend was dominated by the effect observed across clusters of male runners, indicating that geometric effects may be more relevant to BSI risk in males, or that other factors masked the relationship in females. More broadly, this work outlines a methodological approach for distilling complex geometric differences into simple metrics that relate to injury risk.

Physiological biomarker monitoring during arduous military training: Maintaining readiness and performance

OBJECTIVES

Physiological and psychological stressors can degrade soldiers' readiness and performance during military training and operational environments. Integrative and holistic assessments of biomarkers across diverse human performance optimization domains during multistressor training can be leveraged to provide actionable insight to military leadership regarding service member health and readiness.

DESIGN/METHOD

A broad categorization of biomarkers, to include biochemical measures, bone and body composition, psychometric assessments, movement screening, and physiological load can be incorporated into robust analytical pipelines for understanding the complex factors that impact military human performance.

RESULTS

In this perspective commentary we overview the rationale, selection, and methodologies for monitoring biomarker domains that are relevant to military research and specifically highlight methods that have been incorporated in a research program funded by the Office of Naval Research, Code 34 Biological and Physiological Monitoring and Modeling of Warfighter Performance.

CONCLUSIONS

The integration of screening and continuous monitoring methodologies via robust analytical approaches will provide novel insight for military leaders regarding health, performance, and readiness outcomes during multistressor military training.