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1 INJURY PREVENTION REPORT NO. 12-HF INJURY INCIDENCE AND INJURY RISK FACTORS AMONG SOLDIERS IN THE U.S. ARMY ORDNANCE SCHOOL ABERDEEN PROVING GROUND, MARYLAND JANUARY 2000 JUNE 2003 Approved for public release; distributio ulimited. Prevetive Medicie Survey: 40-5f1 1

2 Stadard Form 298 REPORT DOCUMENTATION PAGE Form App3roved OMB The public reportig burde for this collectio of iformatio is estimated to average 1 hour per respose, icludig the time for reviewig istructios, searchig existig data sources, gatherig ad maitaiig the data eeded, ad completig ad reviewig the collectio of iformatio. Sed commets regardig this burde estimate or ay other aspect of this collectio of iformatio, icludig suggestios for reducig the burde, to Departmet of Defese, Washigto Headquarters Services, Directorate for Iformatio Operatios ad Reports ( ), 1215 Jefferso Davis Highway, Suite 1204, Arligto, VA Respodets should be aware that otwithstadig ay other provisio of law, o perso shall be subject to ay pealty for failig to comply with a collectio of iformatio if it does ot display a curretly valid OMB cotrol umber. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM-YYYY) July REPORT TYPE Fial 4. TITLE AND SUBTITLE Ijury Icidece ad Ijury Risk Factors Amog Soldiers i the Uited States Army Ordace School 3. DATES COVERED (From To) Jauary 2000-Jue a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Tyso Grier, Stephaie Morriso, Joseph J Kapik, Michelle Caham-Chervak, Bruce H Joes 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) U.S. Army Ceter for Health Promotio ad Prevetive Medicie Aberdee Provig Groud, MD 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 12. DISTRIBUTION/AVAILABILITY STATEMENT Approved for public release; distributio is ulimited 13. SUPPLEMENTARY NOTES 8. PERFORMING ORGANIZATION REPORT NUMBER 12-HF SPONSOR/MONITOR S ACRONYM(S) 11. SPONSOR/MONITOR S REPORT NUMBER(S) 14. ABSTRACT This study examied risk factors for time-loss ijuries durig U.S. Army Ordace School Advaced Idividual Traiig (AIT). Participats were soldiers (= 3757 me, =498 wome) attedig Ordace AIT from Jauary 2000 to Jue Ijuries were obtaied from a ijury surveillace system i the medical cliic servig the AIT soldiers. Potetial ijury risk factors icluded etry-level fitess, demographics, ad lifestyle variables. Fitess variables icluded maximal effort performace o push-ups, sit-ups ad a 2-mile ru. A health questioaire provided data o age, race, rak, curret self reported ijury, curret self reported illess, ad tobacco use. Fitess variables were coverted to four quartiles (Q) based o the distributio of scores (Q1=high performace to Q4=low performace). AIT etry ad completio dates were obtaied from a Army persoel system. Backward steppig Cox regressio examied associatios betwee time-loss ijury ad potetial ijury risk factors. Multivariate hazard ratios (MHR) ad 95% cofidece itervals (95%CI) were calculated. Cumulative time-loss ijury icidece was 31% for me ad 54% for wome. For me, higher risk of ijury resultig i time-loss was idepedetly associated with race (MHR (Native America/Caucasia) = 1.4, 95%CI = ), a curret self reported ijury (MHR (yes/o) = 2.2, 95%CI = ), smokig before eterig the Army (MHR ( 10 cigarettes/osmokers) = 1.3, 95%CI = , MHR (10-20 cigarettes/osmokers)= 1.5, 95%CI= , MHR (>20 cigarettes/osmokers) = 1.9, 95%CI = ), lower sit-up performace (MHR (Q4/Q1) = 1.2, 95%CI = ), ad slower 2-mile ru times (MHR (Q4/Q1)= 1.4, 95%CI = ). For wome, higher risk of ijury was idepedetly associated with race (MHR (Black/Caucasia) = 0.7, 95%CI = ), a curret self reported ijury (MHR (yes/o) = 1.6, 95%CI = ), ad slower 2-mile ru times (MHR (Q4/Q1) = 2.2, 95%CI = ). Risk factors for time-loss ijury i Ordace AIT for both me ad wome icluded race, curret self reported ijuries, ad lower aerobic fitess. Smokig cessatio classes ad fitess traiig prior to etry are potetial strategies to reduce ijuries amog soldiers i Ordace School AIT. 15. SUBJECT TERMS Ijury, smokeless tobacco, tobacco, military, ordace school 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT a. REPORT Uclassified b. ABSTRACT Uclassified c. THIS PAGE Uclassified 18. NUMBER OF PAGES 19a. NAME OF RESPONSIBLE PERSON Tyso Grier 19b. TELEPHONE NUMBER (iclude area code) /3534

3 DEPARTMENT OF THE ARMY US ARMY PUBLIC HEALTH COMMAND (PROVISIONAL) 5158 BLACKHAWK ROAD ABERDEEN PROVING GROUND MD MCHB-TS-DI EXECUTIVE SUMMARY INJURY PREVENTION REPORT NO. 12-HF INJURY INCIDENCE AND INJURY RISK FACTORS AMONG SOLDIERS IN THE U.S. ARMY ORDNANCE SCHOOL ABERDEEN PROVING GROUND, MARYLAND JANUARY 2000 JUNE PURPOSE. From Jauary 2000 to Jue 2003, the U.S. Army Public Health Commad (Provisioal), formerly kow as the U.S. Army Ceter for Health Promotio ad Prevetive Medicie, ad the Kirk U.S. Army Health Cliic collaborated with the 143 rd Ordace Battalio at Aberdee Provig Groud (APG), Marylad to idetify ijuries ad ijury risk factors durig advaced idividual traiig (AIT). This report provides the results of this collaboratio by addressig ijury rates ad ijury risk factors amog Soldiers i AIT at the Ordace School. 2. METHODS. a. Participats were Army Service members attedig AIT at the Edgewood Area of APG from Jauary 2000 to Jue These Service members were traiig to qualify for oe of five differet Military Occupatioal Specialties (MOSs). These MOSs icluded track vehicle repairer (MOS 63H), wheeled vehicle repairer (MOS 63W), selfpropelled field artillery system mechaic (MOS 63D), fuel ad electrical system repairer (MOS 63G), ad track vehicle mechaic (MOS 63Y). b. O arrival at APG, each Service member was asked to complete a Soldier health i-processig questioaire. The questioaire icluded questios about the demographics ad lifestyle characteristics of Service members. Iformatio requested icluded whether or ot the studet curretly had a ijury or illess perceived to affect their AIT performace, history of tobacco use, date of birth, geder, rak, race, ad basic combat traiig (BCT) locatio. Army Physical Fitess Test (APFT) data were obtaied from the 143 rd Ordace Battalio Traiig ad Operatios (S-3) office. c. Ijuries occurrig durig traiig were obtaied from a ijury surveillace system i the medical cliic servig the AIT Soldiers. Every time a Soldier reported to the medical cliic, a medical provider would fill out a ijury sheet. The ijury sheet had boxes for the medical provider to check that idicated the type of ijury that had occurred ad the umber of profile or quarter days give to the Soldier. Ijuries from the data sheet were classified ito four categories: time-loss ijuries, overuse time-loss ijuries, lower extremity overuse time-loss ijuries ad traumatic time-loss ijuries. Time-loss ijuries iclude a ijury of ay type plus a profile of oe or more days.

4 EXSUM, Ijury Prevetio Report. 12-HF , Jauary 2000 Jue 2003 d. The Statistical Package for the Social Scieces, Versio 16.0, was used for statistical aalysis. Potetial risk factors for time-loss ijuries, overuse time-loss ijuries, lower extremity overuse time-loss ijuries ad traumatic time-loss ijuries were explored usig Cox regressio (separate models were developed for each ijury category). Hazard ratios ad 95 percet cofidece itervals (CIs) were calculated for each potetial ijury risk factor. Variables from the uivariate aalysis with a statistical sigificace of p 0.10 were selected for a backward-steppig multivariate Cox regressio. Multivariate hazard ratios (MHRs) ad 95 percet CIs were calculated. For the Cox regressio, APFT scores were coverted to four quartiles (Qs) based o the distributio of scores where Q1 = high performace ad Q4=low performace. 3. RESULTS. a. There were 3757 me ad 498 wome ivolved with the project. A majority of the subjects were Caucasia me betwee the ages of 17 ad 19 who had atteded BCT at Fort Kox ad were wheeled vehicle repairers (MOS 63W) of lower military rak (E1) ad osmokers ad o-smokeless tobacco users. Durig the course of their Ordace School traiig, 31 percet of me ad 54 percet of wome had oe or more time-loss ijuries; the time-loss ijury rate for me over this time period was 34.9 ijuries/10,000 perso-days, ad the rate for wome was 60.8 ijuries/10,000 persodays. b. Multivariate logistic regressio results follow. (1) Time-Loss Ijury. (a) For me, a higher risk of time-loss ijury was associated with the Native America race (MHR (Native America/Caucasia) = 1.4, 95 percet CI = ); a curret self-reported ijury (MHR (yes/o) = 2.2, 95 percet CI = ); smokig before eterig the Army (MHR ( 10 cigarettes/osmokers) = 1.3, 95 percet CI = , MHR (10-20 cigarettes/osmokers) = 1.5, 95 percet CI = , MHR (>20 cigarettes/osmokers) = 1.9, 95 percet CI = ); lower sit-up performace (MHR (Q4/Q1) = 1.2, 95 percet CI = ); ad slower 2-mile ru times (MHR (Q4/Q1) = 1.4, 95 percet CI = ). (b) For wome, a higher risk of time-loss ijury was associated with Caucasia race (MHR (Black/Caucasia) = 0.7, 95 percet CI = ); a curret self-reported ijury (MHR (yes/o) = 1.6, 95 percet CI = ); ad slower 2-mile ru times (MHR (Q4/Q1) = 2.2, 95 percet CI = ). ES-2

5 EXSUM, Ijury Prevetio Report. 12-HF , Jauary 2000 Jue 2003 (2) Overuse Time-Loss Ijury. (a) For me, a higher risk of overuse time-loss ijury was associated with MOS (MHR (fuel ad electrical system repairer (MOS 63G)/track vehicle repairer (MOS 63H)) = 1.5, 95 percet CI = , MHR (track vehicle mechaic (MOS 63Y)/track vehicle repairer (MOS 63H)) = 1.4, 95 percet CI = ); a curret self-reported ijury (MHR (yes/o) = 2.2, 95 percet CI = ); smokig before eterig the Army (MHR (10 20 cigarettes/osmokers) = 1.7, 95 percet CI = , MHR (>20 cigarettes/ osmokers) = 1.9, 95 percet CI = ); lower sit-up performace (MHR (Q4/Q1) = 1.4, 95 percet CI = ); ad slower 2-mile ru times (MHR (Q4/Q1)= 1.5, 95 percet CI = ). (b) For wome, a higher risk of overuse time-loss ijury was idepedetly associated with age (MHR (20 24/17 19) = 0.73, 95 percet CI = 0.5 ); Caucasia race (MHR (Black/Caucasias) = 0.6, 95 percet CI = ); attedig basic traiig at Fort Leoard Wood (MHR (Fort Leoard Wood/Fort Jackso) = 1.6, 95 percet CI = ); a curret self-reported ijury (MHR (yes/o) = 1.5, 95 percet CI = ); ad slower 2-mile ru times (MHR (Q4/Q1)= 2.0, 95 percet CI = ). (3) Lower Extremity Overuse Time-Loss Ijury. (a) For me, a higher risk of time-losslower extremity overuse time-loss ijury was associated with a curret self-reported ijury (MHR (yes/o) = 2.0, 95 percet CI = ); smokig before eterig the Army (MHR (10 20 cigarettes/osmokers) = 1.7, 95 percet CI = , MHR (>20 cigarettes/osmokers) = 2.1, 95 percet CI = ); lower sit-up performace (MHR (Q4/Q1) = 1.5, 95 percet CI = ); ad slower 2-mile ru times (MHR (Q4/Q1) = 1.5, 95 percet CI = ). (b) For wome, a higher risk of time-losslower extremity overuse time-loss ijury was associated with attedig basic traiig at Fort Leoard Wood (MHR (Fort Leoard Wood/Fort Jackso) = 1.7, 95 percet CI = ); ad slower 2-mile ru times (MHR (Q4/Q1)= 1.8, 95 percet CI = ). ES-3

6 EXSUM, Ijury Prevetio Report. 12-HF , Jauary 2000 Jue 2003 (4) Traumatic Time-Loss Ijury. (a) For me, a higher risk of traumatic time-loss ijury was associated with the Black ad Native America races (MHR (Black/Caucasias) = 1.4, 95 percet CI = ), MHR (Native America/Caucasia) = 1.8, 95 percet CI = ); a curret selfreported ijury (MHR (yes/o) = 1.6, 95 percet CI = ); ad smokig before eterig the Army (MHR ( 10 cigarettes/osmokers) = 1.5, 95 percet CI = , MHR (10 20 cigarettes/osmokers) = 1.4, 95 percet CI = , MHR (>20 cigarettes/osmokers) = 1.7, 95 percet CI = ). (b) For wome, a higher risk of traumatic time-loss ijury was associated with a curret self-reported ijury (MHR (yes/o) = 2.2, 95 percet CI = ). 4. DISCUSSION. a. For me, ijury risk was higher i smokers tha osmokers i all four ijury categories i cosoace with previous studies i BCT. There was also a doserespose relatioship showig that the risk of ijury icreases with the umber of cigarettes smoked per day. b. Ijury risk for those with curret self-reported ijuries believed to adversely affect their AIT performace was approximately 2.2 times higher for me ad 1.5 times higher for wome (except i the traumatic ijury category). Previous ijury, both overuse ad traumatic, put Soldiers at a higher risk for curret ijury. Civilia studies have also show that those with a previous ijury had a higher risk of reijury tha those who reported o previous ijury. 5. CONCLUSIONS. This study idetified risk factors for time-loss ijury i Ordace School AIT Soldiers. Overall, 31 percet of me ad 54 percet of wome ivolved i the project icurred at least oe time-loss ijury. Whe examiig ijury risk for all four ijury categories, both cigarette use ad self-reported ijury were associated with a higher risk of ijury i me. For three out of the four ijury categories, self-reported ijury (wome), sit-ups (me) ad the 2-mile ru (me ad wome) were associated with a higher risk of ijury. 6. RECOMMENDATIONS. I a effort to reduce ijuries, surveillace ad trackig of ijuries i AIT Soldiers could alert commaders to elevated levels of ijuries or to ijury outbreaks. Smokig cessatio classes ad fitess traiig prior to etry are potetial strategies to reduce ijuries. ES-4

7 TABLE OF CONTENTS 1. REFERENCES PURPOSE AUTHORITY BACKGROUND LITERATURE... 2 a. Ijury Icidece ad Ijury Risk Factors i Basic Combat Traiig ad Advaced Idividual Traiig... 2 b. Overuse Ijuries c. Traumatic Ijuries METHODS... 3 a. Participats... 3 b. Questioaires... 4 c. Army Physical Fitess Test Scores... 4 d. Ijury Data... 4 e. Data Aalysis RESULTS... 6 a. Descriptive Statistics... 6 b. Risk Factors for Time-Loss Ijury... 8 c. Risk Factors for Overuse Time-Loss Ijury d. Risk Factors for Lower Extremity Overuse Time-Loss Ijury e. Risk Factors for Traumatic Time-Loss Ijury DISCUSSION a. Geeral Fidigs b. Age c. Race d. Basic Traiig Site e. Military Occupatioal Specialty f. Self-Reported Ijury g. Cigarette Use h. Smokeless Tobacco Use i. Muscular Edurace j. Two-Mile Ru Times CONCLUSIONS RECOMMENDATIONS TECHNICAL ASSISTANCE i

8 Appedices A. REFERENCES... A-1 B. SOLDIER HEALTH INPROCESSING QUESTIONNAIRE... B-1 C. INJURY SHEET... C-1 List of Tables 1. Cumulative Icidece of Ijury ad Ijury Icidece Rates Durig Army Basic Traiig Military Occupatioal Specialties at Aberdee Provig Groud Advaced Idividual Traiig Ordace School Soldier Health I-Processig Questioaire Variables (Descriptive Statistics) Army Physical Fitess Test Scores Perso-Time Ijury Icidece Rates for All Four Ijury Outcomes (Ijuries/10,000 Perso-Days) Uivariate Cox Regressio: Risk Factors Associated with Time- Loss Ijuries i Ordace Advaced Idividual Traiig Subjects Multivariate Cox Regressio: Risk Factors Associated with Time- Loss Ijuries i Ordace Advaced Idividual Traiig Subjects Uivariate Cox Regressio: Risk Factors Associated with Overuse Time-Loss Ijuries i Ordace Advaced Idividual Traiig Subjects Multivariate Cox Regressio: Risk Factors Associated with Overuse Time-Loss Ijuries i Ordace Advaced Idividual Traiig Subjects Uivariate Cox Regressio: Risk Factors Associated with Lower Extremity Overuse Time-Loss Ijuries i Ordace Advaced Idividual Traiig Subjects Multivariate Cox Regressio: Risk Factors Associated with Lower Extremity Overuse Time-Loss Ijuries i Ordace Advaced Idividual Traiig Subjects Uivariate Cox Regressio: Risk Factors Associated with Traumatic Time-Loss Ijuries i Ordace Advaced Idividual Traiig Subjects Multivariate Cox Regressio: Risk Factors Associated with Traumatic Time-Loss Ijuries i Ordace Advaced Idividual Traiig Subjects Risk Factors From All Four Ijury Categories Placig Soldiers at a Higher Risk for a Time-Loss Ijury (Multivariate Aalysis) ii

9 INJURY PREVENTION REPORT NO. 12-HF INJURY INCIDENCE AND INJURY RISK FACTORS AMONG SOLDIERS IN THE U.S. ARMY ORDNANCE SCHOOL ABERDEEN PROVING GROUND, MARYLAND JANUARY 2000 JUNE REFERENCES. Appedix A cotais a listig of the refereces used i this report. 2. PURPOSE. From Jauary 2000 to Jue 2003, the U.S. Army Public Health Commad (Provisioal) (USAPHC (Prov)), formerly kow as the U.S. Army Ceter for Health Promotio ad Prevetive Medicie (USACHPPM), ad the Kirk U.S. Army Health Cliic collaborated with the 143 rd Ordace Battalio at Aberdee Provig Groud (APG), Marylad, to idetify ijuries ad ijury risk factors durig advaced idividual traiig (AIT). This report provides the results of this collaboratio by addressig ijury rates ad ijury risk factors amog Soldiers i AIT at the Ordace School. 3. AUTHORITY. Uder Army Regulatio (AR) 40-5 (paragraph 2-19), USACHPPM is resposible for providig support to Army prevetive medicie activities, to iclude iterpretig surveillace data, idetifyig leadig health problems, ad assistig i prevetio ad cotrol of leadig health problems. 1 This project was coducted uder a cooperative agreemet amog the 61st Ordace Brigade, Kirk U.S. Army Health Cliic, ad USACHPPM, all located at APG. 4. INTRODUCTION. Time lost from work ad traiig due to ijuries ca result i decreased military readiess ad ca compromise missio accomplishmet. I 2004, Departmet of Defese (DOD) Service members experieced almost 25 millio days of limited duty due to ijuries. The top five ijuries raked by the umber of days of limited duty were lower extremity overuse (pai, iflammatio ad stress fractures); lower extremity fractures; upper extremity fractures; torso overuse (pai, iflammatio, ad stress fractures); ad lower extremity sprais ad strais. 2 I a U.S. Marie Corps basic traiig study, ivestigators estimated that ijuries amog 22,000 male recruits resulted i more tha 53,000 lost traiig days at a cost of $16.5 millio (1993 dollars). 3 Other researchers examiig ifatry Soldiers foud that fractures resulted i a average of 103 days of limited duty, sprais a average of 17 days of limited duty, tediitis a average of 7 days of limited duty, ad strais ad musculoskeletal pai a average of 3 days of limited duty. 4 I basic combat traiig (BCT), the icidece of ijury has raged from 21 percet to 42 percet for me ad from 41 percet to 67 percet for wome. 5 There are oly two previous reports o ijuries ad ijury risk factors amog Soldiers i AIT. Oe study ivolved medic AIT 6 ad the other ivestigatio was a abstract reportig the prelimiary results from the preset project. 7

10 5. BACKGROUND LITERATURE. a. Ijury Icidece ad Ijury Risk Factors i Basic ad Advaced Idividual Traiig. (1) Cumulative ijury icidece (proportio of traiees who experiece oe or more ijuries durig traiig) ad ijury rates (ijured traiees per moth) have bee examied i the basic traiig uits of the Army as well as i a Army AIT ivestigatio. 6,8 22 These data are show i Table 1. I October 1998, Army BCT was exteded from 8 to 9 weeks; therefore studies performed before ad after this time are desigated i Table 1 to reflect the icreased time Soldiers were at risk i the ivestigatios subsequet to October Table 1. Cumulative Icidece of Ijury ad Ijury Icidece Rates Durig Army Traiig Army Basic Combat Traiig Medic Advaced Idividual Traiig Legth of Traiig (weeks) 8 weeks 9 weeks 10 weeks Study (Referece Number) tes: a Ijury data from self-report questioaire b ND= data collected o other geder c Cohort study with two groups d Ijury data from surveillace system Year Data Collected Recruits () Cumulative Ijury Icidece (%) Ijury Icidece Rate (%/moth) Me Wome Me Wome Me Wome 12 a , ND b 165 ND b 66.7 ND b c / / / / / / cd / / / / / / , (2) I additio to cumulative ijury icidece ad ijury rates, ijury risk factors have bee idetified. Ijury risk factors idetified durig basic traiig icluded female 2

11 geder, low aerobic fitess, cigarette smokig prior to BCT, low physical activity prior to basic traiig, low muscular edurace, ad traiig i the summer compared to 8 16, traiig i the fall. A majority of the ijuries occurrig i Service members ca be classified as either overuse or traumatic ijury. 2 b. Overuse Ijuries. Overuse ijuries are the result of abormal ad repetitive stress resultig i microtrauma to the soft tissues, boes or joits. 28 Some examples of overuse ijuries iclude shi splits, tedoitis, stress fractures ad bursitis. 29 I a study ivestigatig ijuries occurrig i Army BCT ad AIT, ivestigators foud the largest proportio of ijuries i both BCT ad AIT were of the overuse type ad ivolved the lower body. 6 I a study of Marie Corps basic traiig, ivestigators foud that approximately 80 percet of ijuries were the overuse type ad ivolved the lower extremities (primarily the kee ad akle/foot regios). 3 c. Traumatic Ijuries. Traumatic ijuries are a result of a outside aget or force that causes acute damage or harm to the structure or fuctio of the body. 28 Some examples of traumatic ijuries iclude cotusios, fractures, joit dislocatios, cocussios, strais ad sprais. 29 I athletes the majority of traumatic ijuries relates to overstretchig of the soft tissue. 30 Whe soft tissue is suddely stretched beyod its yield poit, it will tear or rupture. The muscles most proe to overstretchig or tearig are those that cross two joits. 30 Risk factors associated with traumatic ijuries iclude previous ijury, tobacco use, ad stregth imbalaces. I regard to previous ijuries, a ivestigatio foud that basketball players with a history of akle ijuries were 5 times more likely to sustai aother akle ijury. 31 For tobacco use, cigarette smokers have bee show to have higher scores o various measures of risk-takig behaviors possibly placig them at a higher risk of icurrig a traumatic ijury. 32 Muscle stregth ad balace abormalities have also bee ivestigated ad associated with acute muscle ijuries. 33,34 6. METHODS. a. Participats. Participats were Army persoel Service members attedig AIT at APG (Edgewood Area) from Jauary 2000 to Jue Soldiers attedig AIT i the Edgewood Area of APG traied to qualify for oe of five differet military occupatioal specialties (MOSs) (Table 2). There were three compaies (Alpha, Bravo, ad Charlie) i the sigle traiig battalio at the Edgewood Area of APG (143 rd Ordace Battalio). 3

12 Table 2. Military Occupatioal Specialties at Aberdee Provig Groud Military Occupatioal Specialty Weeks of Traiig Track Vehicle Repairer (63H) 16 Wheeled Vehicle Repairer (63W) 13 Self Propelled Field Artillery System Mechaic (63D) 10 Fuel ad Electrical System Repairer (63G) 9 Track Vehicle Mechaic (63Y) 12 b. Questioaires. Upo arrival at APG, each Service member was asked to complete the Soldier health i-processig (SHIP) questioaire (appedix B) as a part of the i-processig procedures. The questioaire asked the Service members about their demographic ad lifestyle characteristics. Iformatio requested icluded rak, race, geder, date of birth, BCT site, whether or ot the studet curretly had a ijury or illess perceived to affect their AIT performace, ad history of tobacco use. c. Army Physical Fitess Test Scores. Army Physical Fitess Test (APFT) data were obtaied from the 143 rd Ordace Battalio Traiig ad Operatios (S-3) office. The APFT cosisted of three evets: a 2-miute maximal effort push-up evet, a 2- miute maximal effort sit-up evet, ad a 2-mile ru performed for time. For the pushup, the subject lowered his or her body i a geerally straight lie to a poit where his or her upper arm was parallel to the groud, ad the retured to the startig poit with elbows fully exteded. For the sit-up, the subject s kees were bet at a 90 agle, figers were iterlocked behid the head, ad a secod perso held the subject s akles while the subject kept his or her heels firmly o the groud. The subject raised his upper body to a vertical positio so that the base of the eck was aterior to the base of the spie ad the retured to the startig positio. Scores were the umber of push-ups ad sit-ups that were successfully completed withi the separate 2-miute time periods. The performace measure for the ru was the time take to complete the 2-mile distace. Time betwee evets was o less tha 10 miutes. d. Ijury Data. Ijuries were obtaied from a ijury surveillace system i the medical cliic servig the AIT Soldiers. Every time a Soldier reported to the medical cliic for a ijury, a medical provider would fill out a ijury sheet (appedix C). The medical provider could record the type of ijury that occurred ad the umber of profile or quarter days give to the Soldier by checkig the appropriate boxes o the ijury sheet. Ijuries from the data sheet were the classified ito four categories: time-loss ijuries, overuse time-loss ijuries, lower extremity overuse time-loss ijuries, ad traumatic time-loss ijuries. Time-loss ijuries icluded a ijury of ay type (overuse, traumatic, other, ukow) plus a profile of 1 or more days. Overuse time-loss ijuries were idetified as such by the medical provider i item 4 (Ijury Category) o the ijury 4

13 sheet ad icluded a profile of oe or more days. Lower extremity overuse time-loss ijuries were idetified as overuse ijuries o the ijury sheet i item 4 (Ijury Category) ad icluded a profile of 1 or more days, but were limited to the ijuries occurrig to the leg (upper ad lower), kee, akle ad foot. Traumatic time-loss ijuries were idetified as such o the ijury sheet i item 4 (Ijury Category) ad icluded a profile of 1 or more days. e. Data Aalysis. (1) The questios about tobacco use o the SHIP survey (appedix B) asked if the Service member had smoked oe or more cigarettes withi the 30 days prior to BCT ad if he or she had smoked o 20 of the 30 days prior to BCT. If Soldiers aswered yes to smokig oe or more cigarettes withi the last 30 days prior to BCT, but o to the questio askig if they had smoked o 20 or more days i the 30 days prior to BCT, they were cosidered a occasioal smoker. If they aswered yes to smokig o 20 of the last 30 days prior to BCT, they were cosidered a frequet smoker. Those who aswered yes to usig smokeless tobacco at least oce i the 30 days prior to BCT, but o to the questio askig if they had used smokeless tobacco o 20 or more days i the 30 days prior to BCT, were cosidered occasioal smokeless tobacco users, ad those who reported usig smokeless tobacco o 20 or more days i the 30 days prior to BCT were cosidered frequet smokeless tobacco users. (2) The age of the Soldier was determied by his or her respose to questio 9 o the SHIP survey (appedix B). Age was the grouped ito three categories: age years, years, ad 25+ years. (3) Cumulative time-loss ijury icidece rates were calculated as follows: (Soldiers with 1 time-loss ijury)/(total umber of Soldiers i the Ordace School) X 100% (4) Perso-time ijury icidece rates for each ijury category were calculated as follows: (Soldiers with 1 time-loss ijury)/(total Soldier days i the Ordace School X 10,000) (5) The Statistical Package for the Social Scieces (SPSS), Versio 16.0, was used for statistical aalysis. Descriptive statistics (frequecies) were calculated for demographics (age, geder, race, military rak); BCT site; a curret self-reported ijury; a curret self-reported illess; tobacco use variables; ad push-ups, sit-ups, ad the 5

14 2- mile ru. Potetial risk factors for time-loss ijury, overuse time-loss ijury, lower extremity overuse time-loss ijury, ad traumatic time-loss ijury were explored usig uivariate ad multivariate Cox regressio. Hazard ratios ad 95 percet cofidece itervals (CIs) were calculated for each risk factor. Variables from the uivariate aalysis with a statistical sigificace of p 0.10 were selected for a backward-steppig multivariate Cox regressio. Sice all of the tobacco variables were correlated (60 percet of smokeless users were also smokers), it was decided to oly use the questio, How may cigarettes were smoked i the last 30 days before BCT, i the multivariate models. Multivariate hazard ratios (MHRs) ad 95 percet CIs were calculated. For the Cox regressio, APFT scores were coverted to four quartiles (Qs) based o the distributio of scores where Q1 = high performace ad Q4 = low performace. 7. RESULTS. a. Descriptive Statistics. (1) There were 3757 me ad 498 wome ivolved i the project. Table 3 displays the results from the SHIP questioaire. A majority of the subjects were Caucasia me betwee the ages of 17 ad 19 who had atteded BCT at Fort Kox ad were wheeled vehicle repairers (MOS 63W) of lower military rak (E1) ad osmokers ad o-smokeless tobacco users. The mea age (± stadard deviatio) for both me ad wome was 20 ± 3 years. Most of the wome had atteded BCT at Fort Jackso. A self-reported ijury perceived to egatively affect AIT performace was reported by 7 percet of subjects, ad a self-reported illess perceived to egatively affect AIT performace was reported by 2 percet of the subjects. (2) Whe asked about smokeless tobacco use, me were 2.5 times more likely to be occasioal smokeless tobacco users ad 5.5 times more likely to be frequet smokeless tobacco users whe compared to wome. Whe asked if they had a curret ijury perceived to egatively affect AIT performace, wome were 2.3 times more likely to aswer yes whe compared to me. 6

15 Table 3. Advaced Idividual Traiig Ordace School Soldier Health I-Processig Questioaire Variables (Descriptive Statistics) Me Wome Me ad Variable Level of Variables (%) (%) Wome (%) Me Geder Wome 3757 (100) 498 (100) 4255 (100) Age Race Rak Basic Traiig Site Military Occupatioal Specialty Self-Reported Ijury Self-Reported Illess Cigarette Use How may cigarettes smoked per day? Smokeless Tobacco Use How much smokeless tobacco used per day? Me ad Wome years years 25+ years Caucasia Asia Black Hispaic Native E1 E2 E3 E4+ Fort Jackso Fort Kox Fort Leoard Wood Fort Beig Fort Sill Track Vehicle Repairer (63H) Wheeled Vehicle Repairer (63W) Self-Propelled Field Artillery System Mechaic (63D) Fuel ad Electrical System Repairer (63G) Track Vehicle Mechaic (63Y) Missig smoker Occasioal Frequet smoker Missig -user Occasioal smokeless Frequet smokeless -user 1 ca 1 ca or more 2 cas Missig 2067 (55) 1324 (35) 366 (10) 2452 (65) 103 (3) 480 (13) 506 (14) 216 (6) 2135 (57) 911 (24) 640 (17) 71 (2) 907 (24) 2135 (57) 189 (5) 357 (10) 169 (5) 554 (15) 2168 (58) 214 (6) 286 (8) 535 (14) 3524 (94) 233 (6) 3675 (98) 69 (2) 13 (0.3) 2166 (58) 201 (5) 1390 (37) 2166 (58) 367 (10) 582 (16) 408 (11) 234 (6) 3158 (84) 171 (5) 428 (11) 3158 (84) 262 (7) 122 (3) 27 (1) 188 (5) 242 (49) 17 1 (34) 85 (17) 330 (66) 9 (2) 87 (18) 44 (9) 28 (6) 241 (48) 140 (28) 101 (20) 16 (3) 401 (81) 0 (0) 69 (14) 0 (0) 28 (6) 59 (12) 352 (71) 0 (0) 28 (6) 59 (12) 431 (87) 67 (14) 483 (97) 13 (3) 2 (0.4) 296 (59) 34 (7) 168 (34) 296 (59) 65 (13) 58 (12) 40 (8) 39 (8) 481 (97) 8 (2) 9 (2) 481 (97) 6 (1) 2 (0.4) 0 (0) 9 (2) 2309 (54) 1495 (35) 451 (11) 2782 (65) 112 (3) 567 (13) 550 (13) 244 (6) 2376 (56) 1051 (25) 741 (17) 87 (2) 1308 (31) 2135 (50) 258 (6) 357 (8) 197 (5) 613 (14) 2520 (59) 214 (5) 314 (7) 594 (14) 3955 (93) 300 (7) 4158 (98) 82 (2) 15 (0.4) 2462 (58) 235 (6) 1558 (37) 2462 (58) 432 (10) 640 (15) 448 (11) 273 (6) 3639 (86) 179 (4) 437 (10) 3639 (86) 268 (6) 124 (3) 27 (1) 197 (5) 7

16 (3) Table 4 displays APFT scores for me ad wome. Compared to wome, me performed a average of 22 more push-ups, a average of 2 more sit-ups, ad ra the 2 miles 3.4 miutes faster. Table 4. Army Physical Fitess Test Scores Variable Me = 3757 Wome = 498 Mea ±SD Mi Max Mea ±SD Mi Max Push-Ups (Repetitios) 52± ± Sit-Ups (Repetitios) 2-Mile Ru (Miutes) 62± ± ± ± (4) Table 5 displays perso-time ijury icidece rates for time-loss ijury, overuse time-loss ijury, lower extremity overuse time-loss ijury, ad traumatic timeloss ijury for me ad wome. I all cases, ijury rates are higher for me tha wome. Cumulative time-loss ijury icidece was 31percet for me ad 54 percet for wome. Whe icludig both time-loss ijuries ad those ot ivolvig time loss, 36 percet of me ad 61 percet of wome experieced at least oe ijury durig AIT. Table 5. Perso-Time Ijury Icidece Rates for All Four Ijury Outcomes (Ijuries/10,000 Perso-Days) Ijury Outcomes Me Rate per 10,000 Perso-Days Wome Rate per 10,000 Perso-Days Time-Loss Ijuries Overuse Time-Loss Ijuries Lower Extremity Overuse Time-Loss Ijuries Traumatic Time-Loss Ijuries b. Risk Factors for Time-Loss Ijury. (1) Table 6 displays the results of the uivariate Cox regressio with time-loss ijury as the depedet variable. For me, time-loss ijury risk was higher amog those who were Native America (relative to Caucasia), of lower military rak (E1 relative to E2), who had atteded BCT at Fort Jackso (relative to Fort Kox) ad were smokers ad/or smokeless tobacco users, with a self-reported ijury, lower push-up 8

17 performace, lower sit-up performace, ad slower two-mile ru times. For wome, time-loss ijury risk was higher amog those who were Caucasia (relative to Black), ad frequet smokers ad/or occasioal smokeless tobacco users, with a self-reported ijury, lower push-up performace, ad slower 2-mile ru times. Table 6. Uivariate Cox Regressio: Risk Factors Associated with Time-Loss Ijuries i Ordace Advaced Idividual Traiig Me Wome Variable Age Group Race Rak Basic Traiig Site Military Occupatioal Specialty Self-Reported Illess Self-Reported Ijury Cigarette Use 30 Days Before BCT How May Cigarettes (cig) i 30 Days Before BCT? Smokeless Tobacco Use 30 Days Before BCT How May Cas of Smokeless Tobacco 30 Days Before BCT? Variable Level years years 25+ years Caucasia Asia Black Hispaic Native E1 E2 E3 E4+ Ft Jackso Ft Kox Ft Wood Ft Beig Ft Sill (63H) (63W) (63D) (63G) (63Y) smokers Occasioal Frequet (smokers) 10 cig or less cig 20 cig or more user Occasioal Frequet 0 (user) Less tha 1 1 o average 2 or more (% TLI) a Hazard Ratio (95% CI) b p- value 2067 (30) 1324 (31) 1.05 ( ) (32) 1.10 ( ) (32) 103 (25) 480 (33) 506 (24) 216 (38) 2135 (32) 911 (28) 640 (29) 71 (31) 907 (34) 2135 (30) 189 (31) 357 (31) 169 (27) 554 (34) 2168 (30) 214 (23) 286 (28) 535 (35) 3675 (31) 69 (33) 3524 (30) 233 (51) 2166 (26) 201 (31) 1390 (38) 2166 (26) 367 (34) 582 (37) 408 (45) 3158 (30) 171 (34) 428 (37) 3158 (30) 262 (37) 122 (39) 27 (44) 0.75 ( ) 1.03 ( ) 0.72 ( ) 1.26 (-1.57) 0.87 (0.75-) 0.92 ( ) 0.92 ( ) 0.86 ( ) 0.90 ( ) 0.92 ( ) 0.78 ( ) 0.96 ( ) 0.97 ( ) 1.14 ( ) 1.13 ( ) ( ) ( ) 1.19 ( ) ( ) 1.29 ( ) 1.50 ( ) 1.97 ( ) 1.13 ( ) 1.31 ( ) 1.31 ( ) 1.42 ( ) 1.59 ( ) Variable Level years years 25+ years Caucasia Asia Black Hispaic Native E1 E2 E3 E4+ Ft Jackso Ft Kox Ft Wood Ft Beig Ft Sill (63H) (63W) (63D) (63G) (63Y) smokers Occasioal Frequet (smokers) 10 cig or less cig 20 cig or more user Occasioal Frequet 0 (user) Less tha 1 1 o average 2 or more (%TLI) a 242 (54) 171 (51) 85 (61) 330 (57) 9 (44) 87 (43) 44 (61) 28 (54) 241 (56) 140 (55) 101 (48) 16 (69) 401 (53) 0 69 (59) 0 28 (54) 59 (63) 352 (53) 0 28 (32) 59 (64) 483 (54) 13 (62) 431 (52) 67 (66) 296 (52) 34 (56) 168 (58) 296 (52) 65 (52) 58 (62) 40 (65) 481 (54) 8 (75) 9 (67) 481 (54) 6 (50) 2 (100) 0 (0) Hazard Ratio p- (95% CI) b value 0.89 ( ) ( ) ( ) 0.69 ( ) 1.18 ( ) 0.83 ( ) 1.02 ( ) 0.78 ( ) 1.36 ( ) 1.18 ( ) ( ) ( ) ( ) ( ) ( ) ( ) 1.08 ( ) ( ) ( ) 1.37 ( ) 1.71 ( ) 2.18 ( ) 1.51 ( ) ( ) 2.17 ( )

18 Table 6. Uivariate Cox Regressio: Risk Factors Associated with Time-Loss Ijuries i Ordace Advaced Idividual Traiig (cotiued) Me Wome Variable Push-Ups (Repetitios) Sit-Ups (Repetitios) 2-Mile Ru (Miutes) Variable Level (% TLI) a Hazard Ratio (95% CI) b p- value 963 (38) 1.63 ( ) 967 (32) 1.38 ( ) 915 (29) 1.22 ( ) (24) 962 (34) 930 (34) 972 (31) 893 (24) 921 (26) 979 (27) 936 (31) 921 (40) 1.47 ( ) 1.51 ( ) 1.34 ( ) 1.02 ( ) 1.23 ( ) 1.64 ( ) a TLI is time-loss ijury. (Values are a percetage of the group that was ijured.) b CI is cofidece iterval. Variable Level (%TLI) a 132 (60) 149 (58) 106 (49) 111 (47) 131 (60) 125 (54) 120 (52) 122 (50) 126 (42) 124 (56) 122 (51) 126 (68) p- Hazard Ratio (95% CI) b value 1.47 ( ) ( ) ( ) ( ) 1.17 ( ) 1.04 ( ) 1.46 ( ) 1.27 ( ) 2.04 ( ) (2) A backward-steppig multivariate aalysis with time-loss ijury as the depedet variable was performed with the followig selected variables for me: race, rak, BCT site, self-reported ijury, the umber of cigarettes smoked i the 30 days before BCT, push-ups, sit-ups, ad the 2-mile ru. For me, rak, BCT, ad push-ups did ot reach the fial step i the model. For wome, the followig variables were selected for iclusio i the multivariate model: race, self-reported ijury, the umber of cigarettes smoked i the 30 days before BCT, push-ups, ad the 2-mile ru. For wome, the umber of cigarettes smoked i the 30 days before BCT ad push-ups did ot reach the fial step i the model. (a) Table 7 displays the results of this aalysis. For me, the risk of time-loss ijury was idepedetly associated with the Native America race (relative to Caucasias), self-reported ijury, the umber of cigarettes smoked i the 30 days before BCT, lower sit-up performace, ad slower 2-mile ru times. For wome, a higher risk of time-loss ijury was idepedetly associated with the Caucasia race (relative to Blacks), self-reported ijury, ad slower 2-mile ru times. Other multivariate models for me were also examied usig the same variables above i the multivariate aalysis. (b) Whe a model was ru limitig the fitess variables to just push-ups, pushups made the fial step ad were foud to place those who performed the least amout of push-ups at a higher risk of ijury whe compared to those who performed the most (MHR (Q4/Q1) = 1.4, 95 percet CI = ). Whe aother model was ru substitutig smokeless tobacco use for the umber of cigarettes smoked per day, smokeless tobacco use made the fial step, ad frequet smokeless users were foud 10

19 to have a higher risk of ijury compared to o-smokeless users (MHR (frequet smokeless users/o-smokeless users) = 1.22, 95 percet CI = ). Table 7. Multivariate Cox Regressio: Risk Factors Associated with Time-Loss Ijuries i Ordace Advaced Idividual Traiig Me (=3523) Wome (=459) Race Variable Self-Reported Ijury How May Cigarettes 30 Days Before BCT Sit-Ups (Repetitios) 2-Mile Ru (Miutes) Variable Level Caucasia Asia Black Hispaic Native 0 (smokers) 10 or less or more p- Hazard Ratio (95% CI) a value 0.69 ( ) ( ) ( ) ( ) ( ) 1.25 ( ) 1.46 ( ) 1.87 ( ( ) 1.35 ( ) 1.21 ( ) 0.96 ( ) 1.07 ( ) 1.41 ( ) Variable Level Caucasia Asia Black Hispaic Native a CI is cofidece iterval. b t etered ito the model because it did ot meet the p<0.10 criteria i the uivariate aalysis p- Hazard Ratio (95% CI) a value 0.92 ( ) ( ) ( ) ( ) ( ) b b b b b b b b ( ) 1.32 ( ) 2.17 ( ) c. Risk Factors for Overuse Time-Loss Ijury. (1) Table 8 displays the results of the uivariate Cox regressio with overuse time-loss ijuries as the depedet variable. For me, overuse time-loss ijury risk was higher amog those who were Caucasia (relative to Hispaic); i the MOS of 63G (fuel ad electrical system repairer) or 63Y (track vehicle mechaic) (relative to 63H (track vehicle repairer)); had a self-reported ijury, smoked ad/or used smokeless tobacco; ad had a lower performace o push-ups, sit-ups, or the 2-mile ru. For wome, overuse time-loss ijury risk was higher amog those who were betwee 17 to 19 years old (relative to 20- to 24-year-olds), Caucasia (relative to Black), of lower military rak (E3 relative to E1), ad who had atteded basic traiig at Fort Leoard Wood (relative to Fort Jackso), had a self-reported ijury, used smokeless tobacco frequetly (relative to o-users), ad had slower 2-mile ru times. 11

20 Table 8. Uivariate Cox Regressio: Risk Factors Associated with Overuse Time-Loss Ijuries i Ordace Advaced Idividual Traiig Me Wome Variable Age Group Race Rak Basic Traiig Site Military Occupatioal Specialty Self-Reported Illess Self-Reported Ijury Cigarette Use 30 Days Before BCT How May Cigarettes (cig) i 30 Days Before BCT? Smokeless Tobacco Use 30 Days Before BCT How May Cas of Smokeless Tobacco 30 Days Before BCT? Push-Ups (Repetitios) Variable Level years years 25+ years Caucasia Asia Black Hispaic Native E1 E2 E3 E4+ Ft Jackso Ft Kox Ft Wood Ft Beig Ft Sill (63H) (63W) (63D) (63G) (63Y) smokers Occasioal Frequet smokers 10 cig or less cig 20 cig or more user Occasioal Frequet user Less tha 1 1 o average 2 or more (% OI) a Hazard Ratio (95% CI) b p- value 2067 (21) 1324 (21) 0.98 ( ) (20) 0.97 ( ) (22) 103 (18) 480 (21) 506 (16) 216 (25) 2135 (22) 911 (19) 640 (20) 71 (20) 907 (21) 2135 (21) 189 (18) 357 (22) 169 (20) 554 (22) 2168 (21) 214 (16) 286 (19) 535 (25) 3675 (21) 69 (26) 3524 (20) 233 (37) 2166 (17) 201 (20) 1390 (27) 2166 (17) 367 (20) 582 (28) 408 (32) 3158 (20) 171 (24) 428 (28) 3158 (20) 262 (29) 122 (27) 27 (33) 963 (27) 967 (23) 915 (18) 912 (16) 0.76 ( ) 0.92 ( ) 0.69 ( ) 1.15 ( ) 0.87 ( ) 0.91 ( ) 0.86 ( ) 0.99 ( ) 0.83 ( ) 1.05 ( ) 0.93 ( ) 1.10 ( ) 1.10 ( ) 1.33 ( ) 1.33 ( ) < ( ) ( ) 1.16 ( ) ( ) 1.17 ( ) 1.75 ( ) 2.07 ( ) 1.17 ( ) 1.48 ( ) 1.55 ( ) 1.41 ( ) 1.76 ( ) 1.82 ( ) 1.50 ( ) 1.17 ( ) Variable Level years years 25+ years Caucasia Asia Black Hispaic Native E1 E2 E3 E4+ Ft Jackso Ft Kox Ft Wood Ft Beig Ft Sill 63H 63W 63D 63G 63Y smokers Occasioal Frequet smokers 10 cig or less cig 20 cig or more user Occasioal Frequet user Less tha 1 1 o average 2 or more (% OI) a Hazard Ratio (95% CI) b p- value 242 (44) 171 (36) 0.75 ( ) (48) 1.11 ( ) (43) 9 (44) 87 (32) 44 (48) 28 (46) 241 (43) 140 (44) 101 (35) 16 (56) 401 (40) 0 69 (51) 0 28 (43) 59 (44) 352 (42) 0 28 (29) 59 (46) 483 (42) 13 (46) 431 (40) 67 (52) 296 (40) 34 (38) 168 (45) 296 (40) 65 (43) 58 (48) 40 (50) 481 (41) 8 (63) 9 (67) 481 (41) 6 (50) 2 (100) 0 (0) 132 (43) 149 (44) 106 (43) 111 (36) 1.01 ( ) 0.70 ( ) 1.23 ( ) 1.03 ( ) 1.02 ( ) 0.71 ( ) 1.42 ( ) 1.40 ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) 1.35 ( ) 1.47 ( ) 1.93 ( ) 2.07 ( ) 1.40 ( ) 2.90 ( ) 1.23 ( ) 1.30 ( ) 1.15 ( )

21 Table 8. Uivariate Cox Regressio: Risk Factors Associated with Overuse Time-Loss Ijuries i Ordace Advaced Idividual Traiig (cotiued) Me Wome Variable Sit-Ups (Repetitios) 2-Mile Ru (Miutes) Variable Level (% OI) a Hazard Ratio (95% CI) b p- value 962 (25) 1.67 ( ) 930 (23) 1.58 ( ) 972 (20) 1.35 ( ) 893 (16) 921 (17) 979 (19) 936 (21) 921 (28) 1.10 ( ) 1.29 ( ) 1.73 ( ) a OI is overuse ijury. (Values are a percetage of the group that was ijured.) b CI is cofidece iterval. Variable Level (% OI) a Hazard Ratio (95% CI) b p- value 131 (47) 1.29 ( ) (44) 1.28 ( ) (38) 1.03 ( ) (38) 126 (33) 124 (39) 122 (42) 126 (53) 1.21 ( ) 1.30 ( ) 1.87 ( ) (2) A backward-steppig multivariate aalysis with overuse time-loss ijury as the depedet variable was performed with the followig selected variables for me: race, MOS, self-reported ijury, the umber of cigarettes smoked i the 30 days before BCT, push-ups, sit-ups, ad the 2-mile ru. For me, race ad push-ups did ot reach the fial step i the model. For wome, the followig variables were selected for iclusio i the multivariate model: age, race, rak, basic traiig site, self-reported ijury, ad the 2-mile ru. For wome, rak did ot reach the fial step i the model. (a) Table 9 displays the results of this aalysis. For me, a higher risk of overuse time-loss ijury was idepedetly associated with MOS (63G (fuel ad electrical system repairer) ad 63Y (track vehicle mechaic) relative to MOS 63H (track vehicle repairer)); self-reported ijury; the umber of cigarettes smoked i the 30 days before BCT; lower sit-up performace; ad slower 2-mile ru times. For wome, a higher risk of overuse time-loss ijury was idepedetly associated with 17- to 19-year-olds (relative to 20- to 24-year-olds), the Caucasia race (relative to Blacks), basic traiig attedace at Fort Leoard Wood (relative to Fort Jackso), a self-reported ijury, ad slower 2-mile ru times. Other multivariate models for me were also examied usig the same variables above i the multivariate aalysis. (b) Whe a model was ru limitig the fitess variables to just push-ups, pushups made the fial step ad were foud to place those who performed the least amout of push-ups at a higher risk of ijury whe compared to those who performed the most (MHR (Q4/Q1) = 1.6, 95 percet CI = ). Whe aother model was ru substitutig smokeless tobacco use for the umber of cigarettes smoked per day, smokeless tobacco use made the fial step, ad frequet smokeless users were foud to have a higher risk of ijury compared to o-smokeless users (MHR (frequet smokeless users/o-smokeless users) = 1.41, 95 percet CI = ). 13

22 Table 9. Multivariate Cox Regressio: Risk Factors Associated with Overuse Time-Loss Ijuries i Ordace Advaced Idividual Traiig Me (=3523) Wome (=498) Variable Age Group Race Basic Traiig Site Military Occupatioal Specialty Self-Reported Ijury How May Cigarettes 30 Days Before BCT Sit-Ups (Repetitios) 2-Mile Ru (Miutes) Variable Level 63H 63W 63D 63G 63Y smokers 10 or less or more Hazard Ratio (95% CI) a p- value b b b b b b b b b b b b ( ) 1.13 ( ) 1.50 ( ) 1.35 ( ) ( ) 1.12 ( ) ( ) 1.93 ( ) 1.38 ( ) 1.42 ( ) 1.24 ( ) ( ) 1.14 ( ) 1.46 ( ) Variable Level Caucasia Asia Black Hispaic Native Ft Jackso Ft Kox Ft Leoard Ft Beig Ft Sill a CI is cofidece iterval. b t etered ito the model because it did ot meet the p<0.10 criteria i the uivariate aalysis Hazard Ratio p- (95% CI) a value 0.73 (0.53-) ( ) ( ) 0.61 ( ) 1.38 ( ) 0.95 ( ) 1.58 ( ) 1.19 ( ) b b b b ( ) 0.04 b b b b b b b b ( ) 1.41 ( ) 1.95 ( ) d. Risk Factors for Lower Extremity Overuse Time-Loss Ijury. (1) Table 10 displays the results of the uivariate Cox regressio with lower extremity overuse time-loss ijuries as the depedet variable. For me, lower extremity overuse time-loss ijury risk was higher for those who were Caucasia (relative to Hispaic), i the MOS of 63Y (track vehicle mechaic) (relative to 63H (track vehicle repairer)), had a self-reported ijury, smoked ad/or used smokeless tobacco, ad had a lower performace o push-ups, sit-ups, ad slower 2-mile ru times. For wome, lower extremity overuse time-loss ijury risk was higher for those who were of lower rak (E1 relative to E3), who had atteded basic traiig at Fort Leoard Wood 14