Hormonal Contraception and Medical Readiness for Female Service Members.

Many female military Service members choose to use hormonal contraception to prevent pregnancy and/or to control or suppress menses. Hormonal contraception, which comes in many different forms based on dose, estrogen/progestin type, and route of administration (oral, vaginal, transdermal, implant, intrauterine device, injectable), may cause side effects, some of which can influence military medical readiness, or the health status necessary to perform assigned missions. This expert review summarizes the evidence around common military-relevant side effects of hormonal contraception that could impact readiness, including effects on weight and body composition, bone health, psychological health, and physical performance, and serves as a tool for uniformed and civilian clinicians counseling female Service members about hormonal contraception. Current evidence suggests some hormonal contraception can lead to weight and fat gain, may modulate susceptibility to mood or mental health disorders, and could impact bone mineral density and stress fracture risk; more research is needed on physical performance effects. Clinicians must be familiar with readiness considerations of each type of hormonal contraception to provide comprehensive patient education and allow for optimal shared decision-making about hormonal contraception use among female Service members. Considering the relative lack of data on the effects of non-oral hormonal contraception routes on readiness outcomes and the growing interest in long-acting reversible contraceptives among female Service members, future research should continue to investigate effects of all hormonal contraception methods available to Service members.

Barriers and facilitators to implementation of musculoskeletal injury mitigation programmes for military service members around the world: a scoping review.

INTRODUCTION: Musculoskeletal injury (MSK-I) mitigation and prevention programmes (MSK-IMPPs) have been developed and implemented across militaries worldwide. Although programme efficacy is often reported, development and implementation details are often overlooked, limiting their scalability, sustainability and effectiveness. This scoping review aimed to identify the following in military populations: (1) barriers and facilitators to implementing and scaling MSK-IMPPs; (2) gaps in MSK-IMPP research and (3) future research priorities. METHODS: A scoping review assessed literature from inception to April 2022 that included studies on MSK-IMPP implementation and/or effectiveness in military populations. Barriers and facilitators to implementing these programmes were identified. RESULTS: From 132 articles, most were primary research studies (90; 68.2%); the remainder were review papers (42; 31.8%). Among primary studies, 3 (3.3%) investigated only women, 62 (69%) only men and 25 (27.8%) both. Barriers included limited resources, lack of stakeholder engagement, competing military priorities and equipment-related factors. Facilitators included strong stakeholder engagement, targeted programme design, involvement/proximity of MSK-I experts, providing MSK-I mitigation education, low burden on resources and emphasising end-user acceptability. Research gaps included variability in reported MSK-I outcomes and no consensus on relevant surveillance metrics and definitions. CONCLUSION: Despite a robust body of literature, there is a dearth of information about programme implementation; specifically, barriers or facilitators to success. Additionally, variability in outcomes and lack of consensus on MSK-I definitions may affect the development, implementation evaluation and comparison of MSK-IMPPs. There is a need for international consensus on definitions and optimal data reporting elements when conducting injury risk mitigation research in the military.

Self-Reported Health Indicators in the US Army: Longitudinal Analysis From a Population Surveillance System, 2014‒2018.

Objectives. To describe health-related behaviors or indicators associated with overall health and well-being using the Global Assessment Tool (GAT), a health behavior and psychosocial questionnaire completed annually by US Army personnel. Methods. We analyzed GAT responses from 2014 to 2018, consisting of 367 000 to 449 000 respondents per year. We used generalized estimating equations to predict the presence of each health behavior or indicator, aggregated by year and stratified on various demographics. Results. Key findings included decreases from 2014 to 2018 in risky health behaviors such as hazardous drinking (7.5% decrease) and tobacco use (7.9% decrease), dietary supplement use (5.0% to 10.6% decrease, depending on type), self-reported musculoskeletal injury (5.1% decrease), and pain interference (3.6% decrease). Physical activity, sleep, and nutritional habits largely remained consistent over time. Conclusions. In the Army, tobacco, alcohol, and risky dietary supplement usage appears to be declining, whereas lifestyle health behaviors have been stable. Whether these trends reflect responses to health education is unknown. The GAT provides useful insights into the health of the Army, which can be leveraged when developing health-related educational programs and policies. Public Health Implications. Health behaviors that have changed less over time (e.g., nutrition, sleep) may require novel approaches compared with those that changed more (e.g., dietary supplement use, drinking). (Am J Public Health. 2021;111(11):2064-2074. https://doi.org/10.2105/AJPH.2021.306456).

Systematic Review of the Association Between Physical Fitness and Musculoskeletal Injury Risk: Part 3-Flexibility, Power, Speed, Balance, and Agility.

de la Motte, SJ, Lisman, P, Gribbin, TC, Murphy, K, and Deuster, PA. Systematic review of the association between physical fitness and musculoskeletal injury risk: part 3-flexibility, power, speed, balance, and agility. J Strength Cond Res 33(6): 1723-1735, 2019-We performed a systematic review and evaluation of the existing scientific literature on the association between flexibility, power, speed, balance, and agility, and musculoskeletal injury (MSK-I) risk in military and civilian populations. MEDLINE, EBSCO, EMBASE, and the Defense Technical Information Center were searched for original studies published from 1970 to 2015 that examined associations between these physical fitness measures (flexibility, power, speed, balance, and agility) and MSK-I. Methodological quality and strength of the evidence were determined after criteria adapted from previously published systematic reviews. Twenty-seven of 4,229 citations met our inclusion criteria. Primary findings indicate that there is (a) moderate evidence that hamstring flexibility, as measured by performance on a sit-and-reach test or active straight leg raise test assessed with goniometry, and ankle flexibility, assessed with goniometry, are associated with MSK-I risk; (b) moderate evidence that lower body power, as measured by performance on a standing broad jump or vertical jump with no countermovement, is associated with MSK-I risk; (c) moderate evidence that slow sprint speed is associated with MSK-I risk; (d) moderate evidence that poor performance on a single-leg balance test is associated with increased risk for ankle sprain; and (e) insufficient evidence that agility is associated with MSK-I risk. Several measures of flexibility, power, speed, and balance are risk factors for training-related MSK-I in military and civilian athletic populations. Importantly, these findings can be useful for military, first responder, and athletic communities who are seeking evidence-based metrics for assessing or stratifying populations for risk of MSK-I.

Systematic Review of the Association Between Physical Fitness and Musculoskeletal Injury Risk: Part 2-Muscular Endurance and Muscular Strength.

de la Motte, SJ, Gribbin, TC, Lisman, P, Murphy, K, and Deuster, PA. A systematic review of the association between physical fitness and musculoskeletal injury risk: part 2-muscular endurance and muscular strength. J Strength Cond Res 31(11): 3218-3234, 2017-This is a systematic review and evaluation of the current evidence on the association between both muscular endurance (ME) and muscular strength (MS) and musculoskeletal injury (MSK-I) risk in military and civilian populations. MEDLINE, EBSCO, EMBASE, and the Defense Technical Information Center were searched for original studies published from 1970 through 2015 which examined associations between physical fitness (ME and MS) and MSK-I in military or civilian populations. Methodological quality and strength of the evidence were determined following criteria adapted from previously published systematic reviews. Forty-five of 4,229 citations met our inclusion criteria. Although results for some tests did vary by sex, taken together, our primary findings indicate there is (a) a strong evidence that poor performance in a push-up test is associated with MSK-I risk; (b) moderate evidence that poor performance in sit-up test is associated with MSK-I risk; (c) moderate evidence that isokinetic ankle and knee flexion strength, and isometric strength assessments at the back, elbow, or knee are associated with MSK-I risk; and (d) limited evidence that poor performance in a pull-up test and isotonic assessments of muscular strength are associated with MSK-I. Several measures of ME/MS are moderately or strongly associated with risk of MSK-I, but additional research is needed to identify and recommend specific assessments of ME/MS that predict MSK-I in both men and women. Future studies should also consider measures of ME and MS as a function of upper body, lower body, and core strength, and their potential association with specific, rather than general, MSK-I.

A Systematic Review of the Association Between Physical Fitness and Musculoskeletal Injury Risk: Part 1-Cardiorespiratory Endurance.

Musculoskeletal injuries (MSK-Is) are a significant health problem for both military and athletic populations. Research indicates that MSK-I is associated with physical fitness; however, the association between specific components of physical fitness and MSK-I in military and athletic populations has not been systematically examined. Our goal was to systematically review the literature to provide a best evidence synthesis on the relationship between components of physical fitness and MSK-I risk in military and civilian athletic populations. This first of 3 manuscripts focuses on cardiorespiratory endurance (CRE). MEDLINE, EBSCO, EMBASE, and the Defense Technical Information Center were searched for original studies published from 1970 through 2015 that examined associations between physical fitness and MSK-I. Forty-nine of 4,229 citations met our inclusion criteria. Primary findings indicate that there is (a) strong evidence that poor performance on a set distance run for time is a predictor for MSK-I risk in both genders; (b) strong evidence that poor performance on timed shuttle runs is a predictor for MSK-I risk in males; (c) moderate evidence in males and limited evidence in females that poor performance on a timed step test is a predictor of MSK-I risk; and (d) limited or insufficient evidence that poor performance on the Cooper run test, maximal and submaximal aerobic graded exercise tests, and the Conconi test are predictors of MSK-I risk in males or females or both. Several measures of CRE are risk factors for training-related MSK-I in military and civilian athletic populations, indicating that CRE may be an important measure for MSK-I risk stratification.

Effect of a Lower Extremity Preventive Training Program on Physical Performance Scores in Military Recruits.

Peck, KY, DiStefano, LJ, Marshall, SW, Padua, DA, Beutler, AI, de la Motte, SJ, Frank, BS, Martinez, JC, and Cameron, KL. Effect of a lower extremity preventive training program on physical performance scores in military recruits. J Strength Cond Res 31(11): 3146-3157, 2017-Exercise-based preventive training programs are designed to improve movement patterns associated with lower extremity injury risk; however, the impact of these programs on general physical fitness has not been evaluated. The purpose of this study was to compare fitness scores between participants in a preventive training program and a control group. One thousand sixty-eight freshmen from a U.S. Service Academy were cluster-randomized into either the intervention or control group during 6 weeks of summer training. The intervention group performed a preventive training program, specifically the Dynamic Integrated Movement Enhancement (DIME), which is designed to improve lower extremity movement patterns. The control group performed the Army Preparation Drill (PD), a warm-up designed to prepare soldiers for training. Main outcome measures were the Army Physical Fitness Test (APFT) raw and scaled (for age and sex) scores. Independent t tests were used to assess between-group differences. Multivariable logistic regression models were used to control for the influence of confounding variables. Dynamic Integrated Movement Enhancement group participants completed the APFT 2-mile run 20 seconds faster compared with the PD group (p < 0.001), which corresponded with significantly higher scaled scores (p < 0.001). Army Physical Fitness Test push-up scores were significantly higher in the DIME group (p = 0.041), but there were no significant differences in APFT sit-up scores. The DIME group had significantly higher total APFT scores compared with the PD group (p < 0.001). Similar results were observed in multivariable models after controlling for sex and body mass index (BMI). Committing time to the implementation of a preventive training program does not appear to negatively affect fitness test scores.

The Relationship Between Functional Movement, Balance Deficits, and Previous Injury History in Deploying Marine Warfighters.

Screening for primary musculoskeletal injury (MSK-I) is costly and time-consuming. Both the Functional Movement Screen (FMS) and the Y-Balance Test (YBT) have been shown to predict future MSK-I. With a goal of optimizing the efficiency of primary MSK-I screening, we studied associations between performance on the FMS and YBT and whether history of MSK-I influenced FMS and YBT scores. In total, 365 deploying Marines performed the FMS and YBT as prescribed. Composite and individual scores were each categorized as high risk or low risk using published injury thresholds: High-risk FMS included composite scores ≤14 and right-to-left (R/L) asymmetry for Shoulder Mobility, In-Line Lunge, Straight Leg Raise, Hurdle Step, or Rotary Stability. High-risk YBT consisted of anterior, posteromedial, and/or posterolateral R/L differences >4 cm and/or composite differences ≥12 cm. Pearson's χ tests evaluated associations between: (a) all FMS and YBT risk groups and (b) previous MSK-I and all FMS and YBT risk groups. Marines with high-risk FMS were twice as likely to have high-risk YBT posteromedial scores (χ = 10.2, p = 0.001; odds ratio [OR] = 2.1, 95% confidence interval [CI] = 1.3-3.2). History of any MSK-I was not associated with high-risk FMS or high-risk YBT. However, previous lower extremity MSK-I was associated with In-Line Lunge asymmetries (χ = 9.8, p = 0.002, OR = 2.2, 95% CI = 1.3-3.6). Overall, we found limited overlap in FMS and YBT risk. Because both methods seem to assess different risk factors for injury, we recommend FMS and YBT continue to be used together in combination with a thorough injury history until their predictive capacities are further established.

Jump-landing differences between varsity, club, and intramural athletes: the Jump-ACL Study.

Abnormal movement patterns have been identified as important prospective risk factors for lower extremity injury, including anterior cruciate ligament injury. Specifically, poor neuromuscular control during the early landing phase has been associated with increased injury risk. Although it is commonly assumed that higher division collegiate athletes generally exhibit better movement patterns than lower division athletes, few studies compare the biomechanical differences on basic tasks such as jump landing between various levels of athletic groups. The objective of this study was to evaluate jump-landing and fitness differences among college-aged Intramural, Competitive Club, and National Collegiate Athletic Association (NCAA) Division I level athletes. Two hundred seventy-seven student-athletes (222 men, 55 women; age 19.3 ± 0.8 years) categorized as NCAA Division I, Competitive Club, or Intramural level athletes were evaluated during a jump-landing task using the Landing Error Scoring System (LESS), a validated qualitative movement assessment. Fitness was measured using the Army Physical Fitness Test (APFT). Results showed no significant differences in landing errors between the levels of athletic group (F(2,267) = 0.36, p = 0.70). There was a significant difference in landing errors between genders (F(1,268) = 3.99, p = 0.05). Significant differences in APFT scores were observed between level of athletic group (F(2,267) = 11.14, p < 0.001) and gender (F(1,268) = 9.27, p = 0.003). There was no significant correlation between the APFT and LESS scores (p = 0.26). In conclusion, higher level athletes had better physical fitness as measured by the APFT but did not as a group exhibit better landing technique. The implications of this research suggest that "high-risk" movement patterns are prevalent in all levels of athletes.

Consortium for health and military performance and American College of Sports Medicine Summit: utility of functional movement assessment in identifying musculoskeletal injury risk.

Prevention of musculoskeletal injuries (MSKI) is critical in both civilian and military populations to enhance physical performance, optimize health, and minimize health care expenses. Developing a more unified approach through addressing identified movement impairments could result in improved dynamic balance, trunk stability, and functional movement quality while potentially minimizing the risk of incurring such injuries. Although the evidence supporting the utility of injury prediction and return-to-activity readiness screening tools is encouraging, considerable additional research is needed regarding improving sensitivity, specificity, and outcomes, and especially the implementation challenges and barriers in a military setting. If selected current functional movement assessments can be administered in an efficient and cost-effective manner, utilization of the existing tools may be a beneficial first step in decreasing the burden of MSKI, with a subsequent focus on secondary and tertiary prevention via further assessments on those with prior injury history.

Determinants of medical care-seeking behavior for musculoskeletal conditions during US: Marine Corps training: A thematic analysis.

CONTEXT: Musculoskeletal injuries (MSK-I) are a well-documented problem in military populations and a leading contributor to disability across military services. However, only a portion of Service members who sustain MSK-I report it to medical providers. Although several studies have identified barriers to seeking medical care in military populations, less is known about what motivates Service members to seek care for MSK-I. OBJECTIVE: To describe determinants of medical care-seeking behavior for MSK-I and/or musculoskeletal pain (MSK-P) in recently-enlisted Marines during military training. DESIGN: Qualitative Study. SETTING: School of Infantry-West (SOI-W), US Marine Corps Base XXX, XXX. PATIENTS OR OTHER PARTICIPANTS: 1,097 US Marines entering Infantry Training Battalion or Marine Combat Training at SOI-W. DATA COLLECTION AND ANALYSIS: Participants completed written surveys at entry to (baseline) and graduation from SOI-W. Closed-ended question responses were used to calculate MSK-I/MSK-P and care-seeking frequencies. Open-ended responses describing determinants of care-seeking behavior were analyzed using inductive thematic analysis. RESULTS: Ten percent of participants self-reported sustaining MSK-I during basic training, while 14% self-reported sustaining MSK-I in SOI-W training. A greater proportion reported seeking medical care for their MSK-I/MSK-P during basic training compared to SOI-W training. The thematic analysis resulted in three main themes that describe drivers and barriers for seeking medical care: 1) Self-perceived need for medical care; 2) Prioritizing military training; and 3) Training-specific influences. CONCLUSION: Understanding determinants of care-seeking behavior is valuable when designing intervention strategies to promote early MSK-I treatment. Our findings add to previous research to elucidate reasons underlying the decisions about care-seeking for MSK-I/MSK-P. Interventions, including educational strategies and direct approaches, like embedding medical providers within units, to minimize barriers to seeking medical care in the military may reduce the burden of MSK-I/MSK-P on Service members throughout their military careers.

Association Between Landing Error Scoring System (LESS) Items and the Incidence Rate of Lower Extremity Stress Fracture.

Background: Lower extremity stress fracture injuries are a major cause of morbidity in physically active populations. The ability to screen for modifiable risk factors associated with injury is critical in developing injury-prevention programs. Purpose: To determine if baseline Landing Error Scoring System (LESS) scores are associated with the incidence rate of lower extremity stress fracture. Study Design: Cohort study; Level of evidence, 2. Methods: A total of 1772 participants with no history of lower extremity stress fracture were included. At preinjury baseline, the authors conducted a lower extremity movement assessment during a jump-landing task using the LESS. Incident lower extremity stress fractures were identified during a 4-year follow-up period. Potential incident cases were reviewed by 2 sports medicine fellowship-trained orthopaedic surgeons blinded to baseline LESS data. Univariate and multivariable Poisson regression models were used to estimate the association between baseline total LESS scores, individual LESS items, and the incidence rate ratio (IRR) of lower extremity stress fracture. Results: A total of 94 incident lower extremity stress fractures were documented, for a 5.3% (95% CI, 4.3%-6.5%) cumulative incidence. The overall LESS score was associated with the incidence rate of lower extremity stress fracture. For every additional movement error documented at baseline, there was a 15% increase in the incidence rate of lower extremity stress fracture (IRR, 1.15 [95% CI, 1.02-1.31]; P = .025). In univariate analyses, ankle flexion, stance width, asymmetrical landing, and trunk flexion at initial contact, in addition to overall impression, were associated with the incidence rate of stress fracture. After controlling for sex and year of entry into the study cohort, participants who consistently landed flat-footed or heel-to-toe were 2.33 times (95% CI, 1.36-3.97; P = .002) more likely to sustain a lower extremity stress fracture. Similarly, participants who consistently demonstrated asymmetric landing at initial contact were 2.53 times (95% CI, 1.34-4.74; P = .004) more likely to sustain a stress fracture. Conclusion: Components of the LESS may be associated with increased lower extremity stress fracture risk and may be helpful in efficiently assessing high-risk lower extremity biomechanics in large groups.

Female Military Officers Report a Desire for Menstrual Suppression During Military Training.

INTRODUCTION: Service women face female-specific challenges that present physiological and logistical burdens and may impact readiness. The stress of training can change menstrual patterns and symptoms, and limited access to hygienic, private facilities can hinder menstrual management. Therefore, suppressing menses with continuous hormonal contraception may be of interest. MATERIALS AND METHODS: The 9-item "Military Women's Attitudes Toward Menstrual Suppression." questionnaire was administered to female officers upon entry (baseline) and graduation (post) from a 6-month secondary training course. Respondents rated their attitudes about menstruation and the stress of training, the desire for menstrual suppression, and the logistical burden of menstruation on a 1 (strongly agree) through 5 (strongly disagree) scale. Wilcoxon Signed Rank Tests determined changes in the distribution of responses from baseline to post. RESULTS: Female officers (n = 108) completed baseline and post questionnaires (age 25.2 ± 0.3 years). At baseline, the majority disagreed/strongly disagreed that the stress of training "makes periods worse than usual" (n = 77, 71%), "increases menstrual symptoms and bleeding" (n = 77, 71%), or "magnifies premenstrual syndrome" (PMS; n = 69, 64%). Although 50% (n = 54) agreed/strongly agreed that "stopping periods while women are training is a good idea," 37% (n = 40) disagreed/strongly disagreed. The majority agreed/strongly agreed that menstrual suppression would prevent "the worry about menstrual supplies" (n = 75, 70%) and "the inconvenience of having a period during training" (n = 69, 64%). Many agreed/strongly agreed that it is difficult to deal with periods during training because "there is no privacy" (n = 52, 48%), "the inability to find adequate facilities" (n = 70, 65%), and "the lack of opportunity to use adequate facilities" (n = 52, 48%). Opinions remained largely consistent from baseline to post. CONCLUSIONS: The desire for menstrual suppression among service women during training is high. Military health care providers should be prepared to counsel service women about strategies to manage menstruation, including the efficacy of continuous hormonal contraception for menstrual suppression. Future studies investigating benefits or risks of continuous hormonal contraception for menstrual suppression in service women should inform the clinical recommendations.

Outcomes of Embedded Athletic Training Services Within United States Air Force Basic Military Training.

CONTEXT: Musculoskeletal injury is the leading cause of attrition from military training. OBJECTIVE: To assess the effect of an embedded athletic training musculoskeletal care model within a basic military training unit. DESIGN: Cluster randomized trial. SETTING: United States Air Force Basic Military Training, Joint Base San Antonio-Lackland. PATIENTS OR OTHER PARTICIPANTS: Military recruits randomly assigned to 1 of 3 training squadrons, 2 control and 1 experimental, between January 2016 and December 2018. INTERVENTION(S): A sports medicine care model was established in 1 squadron by embedding 2 certified athletic trainers overseen by a sports medicine fellowship-trained physician. The athletic trainers diagnosed and coordinated rehabilitation as the primary point of contact for recruits and developed interventions with medical and military leadership based on injury trends. MAIN OUTCOME MEASURE(S): Recruit attrition from basic training due to a musculoskeletal injury. Secondary outcomes were all-cause attrition, on-time graduation, rates of lower extremity injury and stress fracture, rates of specialty care appointments, and fiscal costs. RESULTS: Recruits in the athletic training musculoskeletal care arm experienced 25% lower musculoskeletal-related attrition (risk ratio = 0.75 [95% CI = 0.64, 0.89]) and 15% lower all-cause attrition (risk ratio = 0.85 [95% CI = 0.80, 0.91]), translating to a net saving of more than $10 million. The intervention reduced the incidence of lower extremity stress fracture by 16% (rate ratio = 0.84 [95% CI = 0.73, 0.97]). CONCLUSIONS: An embedded athletic training musculoskeletal care model outperformed usual care across operational, medical, and fiscal outcomes.

Functional Movement Assessments Are Not Associated with Risk of Injury During Military Basic Training.

INTRODUCTION: Musculoskeletal injuries (MSK-I) in the U.S. military accounted for more than four million medical encounters in 2017. The Military Entrance Processing Screen to Assess Risk of Training (MEPSTART) was created to identify MSK-I risk during the first 180 days of military service. METHODS: Active duty applicants to the United States Army, Navy, Air Force, and Marine Corps between February 2013 and December 2014 who consented completed a behavioral and injury history questionnaire and the MEPSTART screen [Functional Movement Screen (FMS), Y-Balance Test (YBT), Landing Error Scoring System (LESS), and Overhead Squat assessment (OHS)] the day they shipped to basic training. Male (n = 1,433) and Female (n = 281) applicants were enrolled and MSK-I were tracked for 180 days. Binomial logistic regression and multivariate Cox proportional hazards modeling were used to assess relationships among MEPSTART screens and MSK-I independent of age, BMI, sex, Service, injury history, and smoking status. Analyses were finalized and performed in 2017. RESULTS: The only functional screen related to injury was the LESS score. Compared to those with good LESS scores, applicants with poor LESS scores had lower odds of MSK-I (OR = 0.54, 95% CI = 0.30-0.97, p = 0.04), and a lower instantaneous risk of MSK-I during the first 180 d (HR = 0.58, 95%CI = 0.34-0.96, p = 0.04). However, secondary receiver operator characteristic (ROC) analyses revealed poor discriminative value (AUC = 0.49, 95%CI = 0.43-0.54). CONCLUSIONS: Functional performance did not predict future injury risk during the first 180 days of service. Poor LESS scores were associated with lower injury risk, but ROC analyses revealed little predictive value and limited clinical usefulness. Comprehensive risk reduction strategies may be preferable for mitigating MSK-I in military training populations.

Comparing self-reported physical activity and sedentary time to objective fitness measures in a military cohort.

OBJECTIVES: Regular vigorous physical activity (PA) and high levels of physical fitness (PF) confer health benefits. Conversely, sedentary time is a risk factor for chronic illness, independent of PA. We evaluated associations between self-reported PA, sedentary time, and objective PF measures in military Service members. DESIGN: Cross-sectional study including 10,105 Air Force Millennium Cohort participants with a valid physical fitness assessment (PFA). METHODS: Linear regression assessed associations between self-report PA, screen time, and usual activity and abdominal circumference (AC) and VO2 max; logistic regression was used for PFA failure. We stratified by age and sex. RESULTS: Men who self-reported high versus low levels of PA had greater AC (19-29 years: ß=0.23in., 95% CI 0.07, 0.39; 30-39 years: ß=0.45in., 95% CI 0.17, 0.72). High versus low self-reported PA was also associated with greater VO2Max (ß=:0.81-1.41mL/kg/min). Self-reported strength training for ≥2days/week was associated with greater VO2Max in 19-29year old men (ß=0.84mL/kg/min, 95% CI 0.09, 0.60) and 30-39year old women (ß=0.74mL/kg/min, 95% CI 0.02, 1.46). For younger men and women,<2h of screen time/day was associated with greater VO2Max (Males 19-29years: ß=0.23mL/kg/min, 95% CI 0.44, 1.26; Females 19-29years: ß=0.83mL/kg/min, 95% CI 0.25, 1.42). PA was not associated with PFA failure, while screen time was (Males OR: 0.32-0.65, 95% CI 0.17-0.92, p<0.001-0.016). CONCLUSIONS: Self-reported PA and screen time were associated with some objective PF measures, including VO2Max and AC. However, screen time alone was associated with PFA failure.

Optimizing Musculoskeletal Performance Through Injury Prevention.

Musculoskeletal injuries (MSK-Is) are ubiquitous throughout the Special Operations Forces (SOF) because of the physical demands of executing missions and carrying heavy loads. Preventing MSK-I has been a priority among SOF but is especially challenging because most MSK-Is are chronic or recurring. For many SOF, musculoskeletal issues and MSK pain are just part of doing their job. Ways to focus, target, and integrate injury prevention efforts across the continuum of training, active duty and SOF status are critical because MSK-Is are a significant barrier to human performance optimization. In this article, we describe how to incorporate these efforts at all levels of training. The need for improving valid, objective, fit-for-full-duty metrics after injury and sharing such information continuously with SOF is discussed. Last, strategies for engaging all levels to begin a culture shift away from the acceptance of MSK-I and pain as a way of life toward embracing MSK-I prevention as a regular part of everyday training are presented.

The Interrelationship of Common Clinical Movement Screens: Establishing Population-Specific Norms in a Large Cohort of Military Applicants.

CONTEXT: Musculoskeletal injuries (MSK-Is) are a leading cause of missed duty time and morbidity in the military. Modifiable risk factors for MSK-Is, such as inadequate core stability, poor movement patterns, and dynamic balance deficits, have not been identified in military applicants on entering service. OBJECTIVE: To establish normative functional movement data using a series of screens in military applicants entering basic training and explore relationships among several movement tests. DESIGN: Cross-sectional study. SETTING: Military Entrance Processing Station. PATIENTS OR OTHER PARTICIPANTS: A total of 1714 (1434 male, 280 female) military applicants entering the US Army (n = 546), Navy (n = 414), Air Force (n = 229), or Marine Corps (n = 525). INTERVENTION(S): We conducted the Functional Movement Screen (FMS), Y-Balance Test (YBT), overhead squat (OHS), and Landing Error Scoring System (LESS). Movements were assessed using the scoring convention for each screen. MAIN OUTCOME MEASURE(S): The FMS, YBT, OHS, and LESS scores and associations among the movement screens as well as clinical meaningfulness. RESULTS: A total of 1037 of the 1714 enrolled applicants were screened on the day they left for basic training. Normative means for this population were established: FMS = 14.7 ± 1.8, YBT anterior-reach difference = 3.1 ± 3.0 cm, mean YBT composite differences = 8.0 ± 6.8 cm, mean YBT composite percentage = 90.9% ± 8.3%, OHS errors = 5.0 ± 2.8, and LESS score = 5.7 ± 2.1. Backward regression results revealed that the YBT composite percentage was related to the FMS and OHS scores in males and to the FMS and LESS results in females. However, clinically meaningful relationships between the tests varied for both males and females. CONCLUSIONS: Sex-normative values for the FMS, YBT, OHS, and LESS screens were established for US military applicants, and some of the assessments overlapped. Overall, males performed better on the OHS and LESS and achieved a greater YBT composite percentage than females. The regression results revealed movement screen performance relationships that varied by sex and clinical meaningfulness. In future studies, we will determine if performance on any of the screens is associated with MSK-Is in basic trainees.

The Effects of an Injury Prevention Program on Landing Biomechanics Over Time.

BACKGROUND: Knowledge is limited regarding how long improvements in biomechanics remain after completion of a lower extremity injury prevention program. PURPOSE: To evaluate the effects of an injury prevention program on movement technique and peak vertical ground-reaction forces (VGRF) over time compared with a standard warm-up (SWU) program. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 1104 incoming freshmen (age range, 17-22 years) at a military academy in the United States volunteered to participate. Participants were cluster-randomized by military company to either the Dynamic Integrated Movement Enhancement (DIME) injury prevention program or SWU. A random subsample of participants completed a standardized jump-landing task at each time point: immediately before the intervention (PRE), immediately after (POST), and 2 (POST2M), 4 (POST4M), 6 (POST6M), and 8 months (POST8M) after the intervention. VGRF data collected during the jump-landing task were normalized to body weight (%BW). The Landing Error Scoring System (LESS) was used to evaluate movement technique during the jump landing. The change scores (Δ) for each variable (LESS, VGRF) between the group's average value at PRE and each time point were calculated. Separate univariate analyses of variance were performed to evaluate group differences. RESULTS: The results showed a greater decrease in mean (±SD) VGRF in the DIME group compared with the SWU group at all retention time points: POST2M (SWU [Δ%BW], -0.13 ± 0.82; DIME, -0.62 ± 0.91; P = .001), POST4M (SWU, -0.15 ± 0.98; DIME,-0.46 ± 0.64; P = .04), POST6M (SWU, -0.04 ± 0.96; DIME, -0.53 ± 0.83; P = .004), and POST8M (SWU, 0.38 ± 0.95; DIME, -0.11 ± 0.98; P = .003), but there was not a significant improvement in the DIME group between PRE and POST8M (Δ%BW, -0.11 ± 0.98). No group differences in Δ LESS were observed. CONCLUSION: The study findings demonstrated that an injury prevention program performed as a warm-up can reduce vertical ground-reaction forces compared with a standard warm-up but a maintenance program is likely necessary in order for continued benefit. CLINICAL RELEVANCE: Injury prevention programs may need to be performed constantly, or at least every sport season, in order for participants to maintain the protective effects against injury.