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Lovalekar M, Keenan KA, Steele E, Cruz DE, Allison K, McFadden BA, Arent SM, Nindl BC. Descriptive Epidemiology of Musculoskeletal Injuries During Marine Corps Recruit Training in Gender-Integrated and Male-Only Training Units. Mil Med 2024; 189:21-29. [PMID: 38920037 DOI: 10.1093/milmed/usad206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 04/14/2023] [Accepted: 05/24/2023] [Indexed: 06/27/2024] Open
Abstract
INTRODUCTION Musculoskeletal injuries (MSIs) occur frequently in military personnel. U.S. Marine Corps (USMC) recruits participate in an intense 13-week training program designed to transform civilians into basically trained Marines, during which they are susceptible to MSIs. Previous injury epidemiology research with USMC recruits was conducted in a non-gender-integrated training. Data for the current study were derived from a larger study, the USMC Gender-Integrated Recruit Training study, that was initiated to provide data-driven recommendations for gender integration during USMC recruit training. The purpose of the current analysis was to describe the unique profile of MSIs during USMC recruit training and compare MSIs between female and male recruits in gender-integrated training. MATERIALS AND METHODS Medical record-reviewed MSI data were obtained for recruits in three models of USMC recruit training: two models of gender-integrated recruit training at Marine Corps Recruit Depot (MCRD) Parris Island-the older Series Track (ST) model and the newer Integrated Company (IC) model, and a Male-Only (MO) cohort at MCRD San Diego. Incidence, anatomic region and subregion, event at the time of MSI, MSI type and onset, and disposition following MSI were described for each model. Group comparisons were conducted using Fisher's exact tests or independent samples t tests, as appropriate. RESULTS MSI data were available for 584 recruits (ST: 98 female recruits, 95 male recruits; IC: 85 female recruits, 106 male recruits; MO: 200 male recruits). The cumulative incidence of MSIs was significantly higher among female compared to male recruits in the ST (59.2% vs. 29.5%, P < .001) and in the IC (25.9% vs. 12.3%, P = .023) cohorts. The most frequent anatomic location for MSIs was the lower extremity (female recruits: ST: 76.5% of MSIs, IC: 88.6%; male recruits: ST: 81.1%, IC: 80.0%, MO: 83.8%). The most frequent body part affected was the hip among female recruits (ST: 26.5% of MSIs, IC: 37.1%). The most frequent body part affected by MSIs among the male recruits was the knee in the ST (32.4%) and IC (53.3%) cohorts and the lower leg (27.0%) in the MO cohort. A significantly greater percentage of female compared to male recruits sustained a hip MSI in the ST (23.5% vs. 2.1%, P < .001) and IC (12.9% vs. 0.0%, P < .001) cohorts. There was no significant difference in knee MSI incidence between sexes in the ST (P = .323) or IC (P = .757) cohorts. A large percentage of MSIs resulted in light duty (female recruits: ST: 69.4% of MSIs, IC: 74.3%; male recruits: ST: 64.9%, IC: 73.3%, MO: 94.6%). CONCLUSIONS This was the first study to assess the burden of MSIs concurrently among female and male USMC recruits in gender-integrated training. MSIs, especially those affecting the lower extremity, continue to occur frequently in this population. Female recruits are more susceptible to MSIs during USMC recruit training compared to male recruits and are especially prone to hip MSIs. Future research should focus on identifying modifiable risk factors for MSIs in this population, with a focus on reducing lower-extremity MSIs in all recruits and hip MSIs in female recruits.
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Affiliation(s)
- Mita Lovalekar
- Neuromuscular Research Laboratory, University of Pittsburgh, Pittsburgh, PA 15203, USA
| | - Karen A Keenan
- Exercise and Sports Science Department, Fitchburg State University, Fitchburg, MA 01420, USA
| | - Elizabeth Steele
- Neuromuscular Research Laboratory, University of Pittsburgh, Pittsburgh, PA 15203, USA
| | - Debora E Cruz
- Neuromuscular Research Laboratory, University of Pittsburgh, Pittsburgh, PA 15203, USA
| | - Katelyn Allison
- Neuromuscular Research Laboratory, University of Pittsburgh, Pittsburgh, PA 15203, USA
| | - Bridget A McFadden
- Department of Exercise Science, Arnold School of Public Health, University of South Carolina, Columbia, SC 29208, USA
| | - Shawn M Arent
- Department of Exercise Science, Arnold School of Public Health, University of South Carolina, Columbia, SC 29208, USA
| | - Bradley C Nindl
- Neuromuscular Research Laboratory, University of Pittsburgh, Pittsburgh, PA 15203, USA
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Gill N, O'Leary T, Roberts A, Liu A, Roerdink M, Greeves J, Jones R. Enforcing walking speed and step-length affects joint kinematics and kinetics in male and female healthy adults. Gait Posture 2023; 103:223-228. [PMID: 37269620 DOI: 10.1016/j.gaitpost.2023.05.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 05/04/2023] [Accepted: 05/24/2023] [Indexed: 06/05/2023]
Abstract
BACKGROUND Individuals increase walking speed by increasing their step-length, increasing their step-frequency, or both. During basic training military recruits are introduced to marching "in-step", and thus the requirement to walk at fixed speeds and step-lengths. The extent to which individuals are required to under- or over-stride will vary depending on their stature, and the stature of others in their section. The incidence of stress fractures in female recruits undergoing basic training is higher than that for their male counterparts. RESEARCH QUESTION Therefore, the purpose of this study was to determine how joint kinematics and kinetics are affected by walking speed, step-length, and sex. METHODS Thirty-seven (19 female) aerobically active non-injured individuals volunteered for this study. Synchronised three-dimensional kinematic and kinetic data were collected while participants walked overground at prescribed speeds. Audio and visual cues were used to control step-lengths. Linear mixed models were run to analyse the effects of speed, step-length condition, and sex on peak joint moments. RESULTS AND SIGNIFICANCE The findings of this study showed that, in general, walking faster and over-striding predominantly increased peak joint moments, suggesting that over-striding is more likely to negatively affect injury risk than under-striding. This is especially important for individuals unaccustomed to over-striding as the cumulative effect of increased joint moments may affect a muscles capability to withstand the increased external forces associated with walking faster and with longer step-lengths, which could then lead to an increased risk of developing an injury.
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Affiliation(s)
- Niamh Gill
- Centre for Health Sciences Research, University of Salford, Manchester, UK.
| | - Thomas O'Leary
- Army Health & Performance Research, Army Headquarters, Andover, UK; Division of Surgery & Interventional Science, UCL, London, UK
| | - Andrew Roberts
- Army Recruit Health & Performance Research, Army Recruit & Initial Training Command, Upavon, UK
| | - Anmin Liu
- Centre for Health Sciences Research, University of Salford, Manchester, UK
| | - Melvyn Roerdink
- Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, Netherlands
| | - Julie Greeves
- Army Health & Performance Research, Army Headquarters, Andover, UK; Norwich Medical School, University of East Anglia, Norwich, UK
| | - Richard Jones
- Centre for Health Sciences Research, University of Salford, Manchester, UK
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O'Leary TJ, Wardle SL, Rawcliffe AJ, Chapman S, Mole J, Greeves JP. Understanding the musculoskeletal injury risk of women in combat: the effect of infantry training and sex on musculoskeletal injury incidence during British Army basic training. BMJ Mil Health 2023; 169:57-61. [PMID: 32111683 DOI: 10.1136/jramc-2019-001347] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 12/11/2019] [Accepted: 12/13/2019] [Indexed: 01/26/2023]
Abstract
INTRODUCTION Until recently, women were excluded from British combat roles. Their risk for musculoskeletal injury during basic training is two to three times higher than men. To better understand the musculoskeletal injury risk of women in British Army infantry basic training, we compared injury incidence between (1) men in standard entry training and men in infantry training, to assess the risk of infantry training; and (2) men and women in both standard entry and officer basic training, to assess the risk in women compared with men. METHODS The incidence of musculoskeletal injury was determined from defence medical records for all men entering infantry training, and for all men and women entering standard entry and officer training, between April 2015 and March 2016. RESULTS 7390 men (standard entry, n=4229; infantry, n=2683; officer, n=478) and 696 women (standard entry, n=626; officer, n=70) entered basic training. Men in infantry training had a lower incidence of musculoskeletal injury (391 vs 417 per 1000 personnel, OR 0.90 (95% CI 0.81 to 0.99), p=0.028) and a higher incidence of stress fracture (14 vs 5 per 1000 personnel, OR 2.80 (95% CI 1.64 to 4.80), p<0.001) than men in standard entry training. Women had a higher incidence of musculoskeletal injury than men in standard entry training (522 vs 417 per 1000 personnel, OR 1.53 (95% CI 1.29 to 1.81), p<0.001) and a higher incidence of stress fracture than men in officer training (114 vs 19 per 1000 personnel, OR 6.72 (95% CI 2.50 to 18.07), p<0.001). CONCLUSION Women in infantry training may be at similar risk for musculoskeletal injury, but at higher risk for stress fracture, compared with their non-infantry counterparts. Women in infantry training may be at higher risk for musculoskeletal injury and stress fracture compared with men in infantry training.
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Affiliation(s)
- Thomas J O'Leary
- Army Health and Performance Research, British Army, Andover, Hampshire, UK
| | - S L Wardle
- Army Health and Performance Research, British Army, Andover, Hampshire, UK
| | - A J Rawcliffe
- Army Recruiting and Initial Training Command, British Army, Upavon, Wiltshire, UK
| | - S Chapman
- Army Recruiting and Initial Training Command, British Army, Upavon, Wiltshire, UK
| | - J Mole
- Defence Statistics (Health), Defence Statistics, Abbey Wood, Bristol, UK
| | - J P Greeves
- Army Health and Performance Research, British Army, Andover, Hampshire, UK.,Norwich Medical School, University of East Anglia, Norwich, Norfolk, UK
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O'Leary TJ, Young CD, Wardle SL, Greeves JP. Gender data gap in military research: a review of the participation of men and women in military musculoskeletal injury studies. BMJ Mil Health 2023; 169:84-88. [PMID: 35042757 DOI: 10.1136/bmjmilitary-2021-002015] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 12/19/2021] [Indexed: 01/26/2023]
Abstract
Servicewomen are at increased risk of musculoskeletal injuries compared with their male counterparts, but women are under-represented in sports medicine research. The aim of this review was to assess the representation of women in military musculoskeletal injury studies. PubMed was searched for human original research studies using the terms Military OR Army OR Navy OR 'Air Force' AND 'musculoskeletal injury' Each study was categorised as epidemiology (basic training), epidemiology (trained personnel), risk factors, interventions and other. The number of male and female participants was retrieved from each study. A total of 262 studies were included: 98 (37%) studies only included men, 17 (6%) studies only included women and 147 (56%) studies included both men and women. A total of 8 051 778 participants were included in these studies (men: 6 711 082, 83%; women: 1 340 696, 17%). The study theme with the greatest proportion of women was musculoskeletal injury epidemiology studies in a basic training population (20% of participants) with the lowest proportion of women in intervention trials (6% of participants). These data suggest women are not under-represented in military musculoskeletal injury studies when considering the gender representation of most militaries. Our data are, however, biased by large epidemiological trials and women were under-represented in intervention trials. The under-representation of women in intervention trials could be due to difficulties in controlling for the effects of female sex steroids on musculoskeletal outcomes, or a focus on interventions in the most arduous military roles where injury risk is highest and women have been previously excluded.
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Affiliation(s)
- Thomas J O'Leary
- Army Health and Performance Research, British Army, Andover, UK .,Division of Surgery and Interventional Science, UCL, London, UK
| | - C D Young
- Army Health and Performance Research, British Army, Andover, UK
| | - S L Wardle
- Army Health and Performance Research, British Army, Andover, UK.,Division of Surgery and Interventional Science, UCL, London, UK
| | - J P Greeves
- Army Health and Performance Research, British Army, Andover, UK.,Division of Surgery and Interventional Science, UCL, London, UK.,Norwich Medical School, University of East Anglia, Norwich, UK
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Factors Predicting Training Delays and Attrition of Recruits during Basic Military Training. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19127271. [PMID: 35742522 PMCID: PMC9223722 DOI: 10.3390/ijerph19127271] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 06/09/2022] [Accepted: 06/09/2022] [Indexed: 01/22/2023]
Abstract
Ensuring a balance between training demands and recovery during basic military training (BMT) is necessary for avoiding maladaptive training responses (e.g., illness or injury). These can lead to delays in training completion and to training attrition. Previously identified predictors of injury and attrition during BMT include demographic and performance data, which are typically collected at a single time point. The aim of this study was to determine individual risk factors for injury and training delays from a suite of measures collected across BMT. A total of 46 male and female recruits undertaking the 12-week Australian Army BMT course consented to this study. Injury, illness, attrition, and demographic data were collected across BMT. Objective measures included salivary cortisol and testosterone, step counts, cardiorespiratory fitness, and muscular endurance. Perceptions of well-being, recovery, workload, fatigue, and sleep were assessed with questionnaires. Baseline and mean scores across BMT were evaluated as predictors of injury and attrition using generalized linear regressions, while repeated-measures ANOVA was used for the group comparisons. From the 46 recruits, 36 recruits completed BMT on time; 10 were delayed in completion or discharged. Multiple risk factors for injury during BMT included higher subjective ratings of training load, fatigue, and stress, lower sleep quality, and higher cortisol concentrations. Higher ratings of depression, anxiety, and stress, and more injuries were associated with a higher risk of delayed completion. Higher concentrations of testosterone and higher levels of fitness upon entry to BMT were associated with reduced risk of injury and delayed completion of BMT. Ongoing monitoring with a suite of easily administered measures may have utility in forewarning risk of training maladaptation in recruits and may complement strategies to address previously identified demographic and performance-based risk factors to mitigate injury, training delays, and attrition.
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Middleton K, Vickery-Howe D, Dascombe B, Clarke A, Wheat J, McClelland J, Drain J. Mechanical Differences between Men and Women during Overground Load Carriage at Self-Selected Walking Speeds. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19073927. [PMID: 35409609 PMCID: PMC8997774 DOI: 10.3390/ijerph19073927] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 03/07/2022] [Accepted: 03/21/2022] [Indexed: 11/22/2022]
Abstract
Few studies have directly compared physical responses to relative loading strategies between men and women during overground walking. This study aimed to compare gait mechanics of men and women during overground load carriage. A total of 30 participants (15 male, 15 female) completed three 10-min walking trials while carrying external loads of 0%, 20% and 40% of body mass at a self-selected walking speed. Lower-body motion and ground reaction forces were collected using a three-dimensional motion capture system and force plates, respectively. Female participants walked with a higher cadence (p = 0.002) and spent less absolute time in stance (p = 0.010) but had similar self-selected walking speed (p = 0.750), which was likely due to the female participants being shorter than the male participants. Except for ankle plantarflexion moments, there were no sex differences in spatiotemporal, kinematic, or kinetic variables (p > 0.05). Increasing loads resulted in significantly lower self-selected walking speed, greater stance time, and changes in all joint kinematics and kinetics across the gait cycle (p < 0.05). In conclusion, there were few differences between sexes in walking mechanics during overground load carriage. The changes identified in this study may inform training programs to increase load carriage performance.
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Affiliation(s)
- Kane Middleton
- Discipline of Sport and Exercise Science, School of Allied Health, Human Services and Sport, La Trobe University, Bundoora 3086, Australia; (D.V.-H.); (A.C.)
- Correspondence:
| | - Danielle Vickery-Howe
- Discipline of Sport and Exercise Science, School of Allied Health, Human Services and Sport, La Trobe University, Bundoora 3086, Australia; (D.V.-H.); (A.C.)
| | - Ben Dascombe
- Applied Sport Science and Exercise Testing Laboratory, School of Life and Environmental Sciences, University of Newcastle, Ourimbah 2258, Australia;
| | - Anthea Clarke
- Discipline of Sport and Exercise Science, School of Allied Health, Human Services and Sport, La Trobe University, Bundoora 3086, Australia; (D.V.-H.); (A.C.)
| | - Jon Wheat
- Academy of Sport and Physical Activity, Sheffield Hallam University, Sheffield S10 2BP, UK;
| | - Jodie McClelland
- Discipline of Physiotherapy, School of Allied Health, Human Services and Sport, La Trobe University, Bundoora 3086, Australia;
| | - Jace Drain
- Land Division, Defence Science and Technology Group, Fishermans Bend 3207, Australia;
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Sammito S, Hadzic V, Karakolis T, Kelly KR, Proctor SP, Stepens A, White G, Zimmermann WO. Risk factors for musculoskeletal injuries in the military: a qualitative systematic review of the literature from the past two decades and a new prioritizing injury model. Mil Med Res 2021; 8:66. [PMID: 34886915 PMCID: PMC8662851 DOI: 10.1186/s40779-021-00357-w] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Accepted: 11/12/2021] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Musculoskeletal injuries (MSkIs) are a leading cause of health care utilization, as well as limited duty and disability in the US military and other armed forces. MSkIs affect members of the military during initial training, operational training, and deployment and have a direct negative impact on overall troop readiness. Currently, a systematic overview of all risk factors for MSkIs in the military is not available. METHODS A systematic literature search was carried out using the PubMed, Ovid/Medline, and Web of Science databases from January 1, 2000 to September 10, 2019. Additionally, a reference list scan was performed (using the "snowball method"). Thereafter, an international, multidisciplinary expert panel scored the level of evidence per risk factor, and a classification of modifiable/non-modifiable was made. RESULTS In total, 176 original papers and 3 meta-analyses were included in the review. A list of 57 reported potential risk factors was formed. For 21 risk factors, the level of evidence was considered moderate or strong. Based on this literature review and an in-depth analysis, the expert panel developed a model to display the most relevant risk factors identified, introducing the idea of the "order of importance" and including concepts that are modifiable/non-modifiable, as well as extrinsic/intrinsic risk factors. CONCLUSIONS This is the qualitative systematic review of studies on risk factors for MSkIs in the military that has attempted to be all-inclusive. A total of 57 different potential risk factors were identified, and a new, prioritizing injury model was developed. This model may help us to understand risk factors that can be addressed, and in which order they should be prioritized when planning intervention strategies within military groups.
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Affiliation(s)
- Stefan Sammito
- Section Experimental Aerospace Medicine Research, German Air Force Centre of Aerospace Medicine, Flughafenstraße 1, 51147 Cologne, Germany
- Occupational Medicine, Faculty of Medicine, Otto-Von-Guericke-University of Magdeburg, 39120 Magdeburg, Germany
| | - Vedran Hadzic
- Faculty of Sport, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Thomas Karakolis
- Defence Research and Development Canada, Toronto, ON M3K 2C9 Canada
| | - Karen R. Kelly
- Warfighter Performance, Naval Health Research Center, San Diego, CA 92106-3599 USA
| | - Susan P. Proctor
- Military Performance Division, US Army Research Institute of Environmental Medicine, Natick, MA 01760 USA
- Research Service, VA Boston Healthcare System, Boston, MA 02130 USA
| | - Ainars Stepens
- Centre for Military Medicine Research, Riga Stradins University, Riga, 1007 Latvia
| | - Graham White
- Human and Social Sciences Group, Defense Science and Technology Laboratory, Portsdown Hill Road, Fareham, PO17 6AD UK
| | - Wes O. Zimmermann
- Department of Military Sports Medicine, Royal Netherlands Army, 3584 AB Utrecht, The Netherlands
- Department of Military/Emergency Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814 USA
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Rhon DI, Greenlee TA, Dickens JF, Wright AA. Are We Able to Determine Differences in Outcomes Between Male and Female Servicemembers Undergoing Hip Arthroscopy? A Systematic Review. Orthop J Sports Med 2021; 9:23259671211053034. [PMID: 34805422 PMCID: PMC8600561 DOI: 10.1177/23259671211053034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Accepted: 08/04/2021] [Indexed: 11/16/2022] Open
Abstract
Background: Female servicemembers sustain higher rates of lower extremity injuries as
compared with their male counterparts. This can include intra-articular
pathology in the hip. Female patients are considered to have worse outcomes
after hip arthroscopy for femoroacetabular impingement and for hip labral
repair. Purpose: To (1) compare published rates of hip arthroscopy between male and female
military servicemembers and (2) determine if there are any sex-based
differences in outcomes after hip arthroscopy in the military. Study Design: Systematic review; Level of evidence, 3. Methods: We reviewed the literature published from January 1, 2000, through December
31, 2020, to identify studies in which hip arthroscopy was performed in
military personnel. Clinical trials and cohort studies were included. The
proportion of women within each cohort was identified, and results of any
between-sex analyses were reported. Results: Identified were 11 studies that met established criteria. Studies included
2481 patients, 970 (39.1%) of whom were women. Surgery occurred between
January 1998 and March 2018. Despite women accounting for approximately 15%
of the active-duty military force, they represented 39.1% (range,
25.7%-57.6%) of patients undergoing hip arthroscopy. In most cases, there
were no differences in self-reported outcomes (pain, disability, and
physical function), return to duty, or medical disability status based on
sex. Conclusion: Women account for approximately 15% of the military, but they made up 40% of
patients undergoing hip arthroscopy. Outcomes were not different between the
sexes; however, definitive conclusions were limited by the heterogeneity of
outcomes, missing data, lack of sex-specific subgroup analyses, and zero
studies with sex differences as the primary outcome. A proper understanding
of sex-specific outcomes after hip arthroscopy will require a paradigm shift
in the design and reporting of trials in the military health system.
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Affiliation(s)
- Daniel I Rhon
- Department of Rehabilitation Medicine, Brooke Army Medical Center, Joint Base San Antonio-Fort Sam Houston, Texas, USA.,Uniformed Services University of Health Sciences, Bethesda, Maryland, USA
| | - Tina A Greenlee
- Department of Rehabilitation Medicine, Brooke Army Medical Center, Joint Base San Antonio-Fort Sam Houston, Texas, USA
| | - Jonathan F Dickens
- Uniformed Services University of Health Sciences, Bethesda, Maryland, USA.,Department of Sports Medicine, Walter Reed National Military Medical Center, Bethesda, Maryland, USA.,John A. Feagin Jr Sports Medicine Fellowship, Keller Army Community Hospital, West Point, New York, USA
| | - Alexis A Wright
- School of Medicine, Tufts University, Boston, Massachusetts, USA
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Vickery-Howe DM, Clarke AC, Drain JR, Dascombe BJ, Middleton KJ. No physiological or biomechanical sex-by-load interactions during treadmill-based load carriage. ERGONOMICS 2020; 63:1175-1181. [PMID: 32441225 DOI: 10.1080/00140139.2020.1772379] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 05/12/2020] [Indexed: 06/11/2023]
Abstract
This study investigated whether physiological demand or gait mechanics differ between sexes during treadmill load carriage. Female (n = 15) and male (n = 15) military recruit-type participants with no load carriage experience completed three 10-minute walking trials at a self-selected speed with increasing relative body-borne loads (0%, 20%, and 40% body weight). A range of cardiorespiratory, perceptual and biomechanical variables were measured. Self-selected walking speed was similar between sexes (4.6-4.8 km·h-1, p > .05) and there were no significant sex-by-load interactions for any variables. Absolute VO2 and VCO2 were greater in males (difference 175-178 mL·min-1, p < .001), however, when relative to body mass, VO2 was similar between sexes (p > .05). Across all loads, cadence was 7 ± 2 steps·min-1 faster (p = .004) and stance time was 0.06 ± 0.02 s shorter (p = .013) in females. Increasing load resulted in greater physiological demand, cadence, % stance time, and step length (p < .05). Practitioner summary: Literature comparing physiological and biomechanical variables between sexes during load carriage is scarce. Physiological and biomechanical sex differences were limited to relative measures associated with physical size (height and mass). Future research may pool male and female participants when conducting trials up to ten minutes in length. Abbreviations: BW: body weight; COM: centre of mass; HR: heart rate; HRmax: maximum heart rate; RER: respiratory exchange ratio; RPE: rating of perceived exertion; VCO2: volume of carbon dioxide; VE: ventilation; VO2: volume of oxygen; VO2max: maximum volume of oxygen.
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Affiliation(s)
- Danielle M Vickery-Howe
- Sport and Exercise Science, School of Allied Health, Human Services and Sport, La Trobe University, Melbourne, Australia
| | - Anthea C Clarke
- Sport and Exercise Science, School of Allied Health, Human Services and Sport, La Trobe University, Melbourne, Australia
| | - Jace R Drain
- Land Division, Defence Science and Technology Group, Fishermans Bend, Australia
| | - Ben J Dascombe
- Applied Sport Science and Exercise Testing Laboratory, School of Life and Environmental Sciences, University of Newcastle, Ourimbah, Australia
| | - Kane J Middleton
- Sport and Exercise Science, School of Allied Health, Human Services and Sport, La Trobe University, Melbourne, Australia
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Molloy JM, Pendergrass TL, Lee IE, Chervak MC, Hauret KG, Rhon DI. Musculoskeletal Injuries and United States Army Readiness Part I: Overview of Injuries and their Strategic Impact. Mil Med 2020; 185:e1461-e1471. [DOI: 10.1093/milmed/usaa027] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 12/07/2019] [Accepted: 01/29/2020] [Indexed: 12/25/2022] Open
Abstract
Abstract
Introduction
Noncombat injuries (“injuries”) greatly impact soldier health and United States (U.S.) Army readiness; they are the leading cause of outpatient medical encounters (more than two million annually) among active component (AC) soldiers. Noncombat musculoskeletal injuries (“MSKIs”) may account for nearly 60% of soldiers’ limited duty days and 65% of soldiers who cannot deploy for medical reasons. Injuries primarily affect readiness through increased limited duty days, decreased deployability rates, and increased medical separation rates. MSKIs are also responsible for exorbitant medical costs to the U.S. government, including service-connected disability compensation. A significant subset of soldiers develops chronic pain or long-term disability after injury; this may increase their risk for chronic disease or secondary health deficits potentially associated with MSKIs. The authors will review trends in U.S. Army MSKI rates, summarize MSKI readiness-related impacts, and highlight the importance of standardizing surveillance approaches, including injury definitions used in injury surveillance.
Materials/Methods
This review summarizes current reports and U.S. Department of Defense internal policy documents. MSKIs are defined as musculoskeletal disorders resulting from mechanical energy transfer, including traumatic and overuse injuries, which may cause pain and/or limit function. This review focuses on various U.S. Army populations, based on setting, sex, and age; the review excludes combat or battle injuries.
Results
More than half of all AC soldiers sustained at least one injury (MSKI or non-MSKI) in 2017. Overuse injuries comprise at least 70% of all injuries among AC soldiers. Female soldiers are at greater risk for MSKI than men. Female soldiers’ aerobic and muscular fitness performances are typically lower than men’s performances, which could account for their higher injury rates. Older soldiers are at greater injury risk than younger soldiers. Soldiers in noncombat arms units tend to have higher incidences of reported MSKIs, more limited duty days, and higher rates of limited duty days for chronic MSKIs than soldiers in combat arms units. MSKIs account for 65% of medically nondeployable AC soldiers. At any time, 4% of AC soldiers cannot deploy because of MSKIs. Once deployed, nonbattle injuries accounted for approximately 30% of all medical evacuations, and were the largest category of soldier evacuations from both recent major combat theaters (Iraq and Afghanistan). More than 85% of service members medically evacuated for MSKIs failed to return to the theater. MSKIs factored into (1) nearly 70% of medical disability discharges across the Army from 2011 through 2016 and (2) more than 90% of disability discharges within enlisted soldiers’ first year of service from 2010 to 2015. MSKI-related, service-connected (SC) disabilities account for 44% of all SC disabilities (more than any other body system) among compensated U.S. Global War on Terrorism veterans.
Conclusions
MSKIs significantly impact soldier health and U.S. Army readiness. MSKIs also figure prominently in medical disability discharges and long-term, service-connected disability costs. MSKI patterns and trends vary between trainees and soldiers in operational units and among military occupations and types of operational units. Coordinated injury surveillance efforts are needed to provide standardized metrics and accurately measure temporal changes in injury rates.
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Affiliation(s)
- Joseph M Molloy
- Oak Ridge Institute for Science and Education, Oak Ridge, TN 37830
- U.S. Army Office of the Surgeon General, Physical Performance Service Line, G 3/5/7, Falls Church, VA 22042
| | - Timothy L Pendergrass
- U.S. Army Office of the Surgeon General, Physical Performance Service Line, G 3/5/7, Falls Church, VA 22042
| | - Ian E Lee
- Solution Delivery Division, U.S. Defense Health Agency, Falls Church, VA 22042
| | - Michelle C Chervak
- U.S. Army Public Health Center, Injury Prevention Program, Aberdeen Proving Ground, Aberdeen, MD 21005
| | - Keith G Hauret
- U.S. Army Public Health Center, Injury Prevention Program, Aberdeen Proving Ground, Aberdeen, MD 21005
| | - Daniel I Rhon
- Oak Ridge Institute for Science and Education, Oak Ridge, TN 37830
- U.S. Army Office of the Surgeon General, Physical Performance Service Line, G 3/5/7, Falls Church, VA 22042
- Center for the Intrepid, Brooke Army Medical Center, Joint Base San Antonio Fort Sam Houston, TX 78234
- Duke Clinical Research Institute, Duke University, Durham, NC 27701
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