1. Physical Activity, Fitness and Injuries Among Women in the Army Michelle Canham Chervak, PhD, MPH Bruce H. Jones, MD, MPH Bradley C. Nindl, PhD 21 May 2014 UNCLASSIFIED

2. U.S. Army Public Health Command 2UNCLASSIFIED Vision: World-Class Provider of Public Health Services across DA and DoD. Mission: Promote health and prevent disease, injury, and disability of Soldiers and military retirees, their Families, and DA Civilian employees; assure effective execution of full spectrum veterinary service for Army and DoD Veterinary missions.

3. Reasons for interest in training related injuries –Physical fitness is a requirement for the Army that needs physical training/exercise –Injuries are a problem for the Army and most result from physical training; women experience more injuries Risk factors for training-related injuries include: –Extrinsic Factors –Intrinsic Factors Conclusions Overview of Factors for Injuries to Women in the Army IMAGE SOURCE: http://www.defenseimagery.mil/ 120109-A-RX742-054http://www.defenseimagery.mil/ UNCLASSIFIED 2

4. Relative Burden of Injuries and Diseases, U.S. Army Active Duty, 2012 Data source: Defense Medical Surveillance System, 2013; Prepared by Army Institute of Public Health, Injury Prevention Program UNCLASSIFIEDIncludes all ICD-9-CM code groups with less than 80,000 medical encounters Diagnosis group Injury contains both injury and musculoskeletal related injuries 3

5. Army OIF-OND/OEF Air Medical Evacuations by Diagnosis Group, 2003 - 2010 1-4 1 Total evacuations: n= 57,968 2 ICD-9 codes obtained from TRAC 2 ES 3 Percents represent the percent of all evacuations in each diagnosis group 4 Operation Iraqi Freedom (OIF-OND) started on 19 March 2003, Operation Enduring Freedom (OEF) started in October 2001 UNCLASSIFIED 4

6. Annual Percent of Service Members with Any Injury or Exercise & Sports Activity (ESA)-Related Injury by Military Service N = 10,692 Service Any Injury (>1)ESA Injury (>1) Percent Injured Percent Injured Army56.629.0 Navy41.419.9 Marine Corps53.032.6 Air Force42.721.8 All Services48.925.4 Source: Status of Forces Survey Analysis 2008, USAPHC Technical Report No. 12-HF-0PDT-08 UNCLASSIFIED 5

7. Risks of Injury for Women Compared to Men Length of Training (weeks) Study Year data Collected Recruits (n) Cumulative Injury Incidence (%) Risk Ratio WomenMenWomenMenWomen:Men 8 weeks Kowal et al. 1978 19787703476226.22.4 Bensel and Kirk 1983 19806441,84041.220.72.0 Jones et al. 1993 198418612450.527.41.8 Bell et al. 1993 198835250957272.1 Jones et al. 1996 19968415965.541.51.6 Knapik et al. 2001 19983056045830.81.9 9 weeks Canham- Chervak et al. 2000 199849865565.3302.2 Knapik et al. 2008 20079152,14764.736.91.8 Source: Knapik, J. et al. USAPHC Epidemiological Report #S.0007856-11, 2012 UNCLASSIFIED 8

8. N Number Injured Follow-Up Injury Rate per 1000 Soldiers per Month Risk Ratio (95% CI) Women4531986 months73 1.16 * (1.0-1.3) Men5,0291,9096 months631 Injury Rates for Women and Men after the Implementation of a Physical Training Program in an Operational Army Unit Source: EDS-IPP, AIPH, APG, MD *p=0.02 N=5482 UNCLASSIFIED 6

9. Casualty Type MaleFemale Cases (n) Percent (%) Incidence per 1,000 Cases (n) Percent (%) Incidence per 1,000 Battle Injury 8,72119.46.21792.71.1 Non-Battle Injury 15,99035.611.51,54223.79.8 Illness 20,22845.014.54,79173.630.9 Total 44,939100.032.26,512100.041.5 Distribution of Casualty Type by Gender for Air Evacuated Soldiers from CENTCOM, OIF/OEF (Army) 2001-2009 Incidence: cases per 1,000 deployed Soldiers Data source: US Transportation Command Regulating and Command & Control Evacuation System (TRAC 2 ES) 9 UNCLASSIFIED 7

10. Extrinsic –Training Amount Type Activity –Equipment –Environment Intrinsic –Gender –Age –Race –Physical Fitness Health Related Skill Related –Multivariate Models Stratified Models Logistic Regression Risk Factors for Training Injuries IMAGE SOURCE: http://www.defenseimagery.mil111101-A-VB845-030http://www.defenseimagery.mil UNCLASSIFIED 9

11. Extrinsic Risk Factors Physical Training and Activity IMAGE SOURCE: Flickr / U.S. Army UNCLASSIFIED 10

12. Injuries per Year among Men and Women by Miles Run per Week Source: Koplan JP, Powell KE, Sikes RK. JAMA; 248:3118, 1982UNCLASSIFIED 11

13. Injury Risks for Female and Male Trainees by Footsteps During BCT Men n=1174 Women n=898 Average # of footsteps per day: Lower=14,772 ± 400; Moderate=16,346 ± 768; Higher=17,948 ± 550 UNCLASSIFIED 12

14. Distribution (%) of Injuries in Women and Men by Activity in Basic Combat Training Source: Knapik J et al. Military Medicine 178(5):500-506, 2013 Fort Leonard Wood, April 2011 Rank order by percent of women injured in each category Men n=4,128; Women n=2,907 UNCLASSIFIED 13

15. Rank order by percent of women injured in each category Men n=1,078; Women n=120 Distribution (%) of Injuries in Women and Men by Activity in an Operational Unit UNCLASSIFIED 14

16. Cause of Injury for Soldiers Air Evacuated from CENTCOM by Gender, OIF/OEF: 2001 – 2009 a Data source: US Transportation Command Regulating and Command & Control Evacuation System (TRAC 2 ES) N: men=10,792; women=947 UNCLASSIFIED 15

17. –Gender –Age Intrinsic Risk Factors IMAGE SOURCE (TOP): Flickr / U.S. Army, (BOTTOM): http://www.defenseimagery.mil/ 111002-A-QD683-210http://www.defenseimagery.mil/ UNCLASSIFIED 16

18. Risks of Injury for Women Compared to Men Length of Training (weeks) Study Year data Collected Recruits (n) Cumulative Injury Incidence (%) Risk Ratio WomenMenWomenMenWomen:Men 8 weeks Kowal et al. 1978 19787703476226.22.4 Bensel and Kisk 1983 19806441,84041.220.72.0 Jones et al. 1993 198418612450.527.41.8 Bell et al. 1993 198835250957272.1 Jones et al. 1996 19968415965.541.51.6 Knapik et al. 2001 19983056045830.81.9 9 weeks Canham- Chervak et al. 2000 199849865565.3302.2 Knapik et al. 2008 20079152,14764.736.91.8 Source: Knapik, J. et al. USAPHC Epidemiological Report #S.0007856-11, 2012 UNCLASSIFIED 18

19. N Number Injured Follow-Up Injury Rate per 1000 Soldiers per Month Risk Ratio (95% CI) Women4531986 months73 1.16 * (1.0-1.3) Men5,0291,9096 months631 Injury Rates for Women and Men after the Implementation of a Physical Training Program in an Operational Army Unit Source: EDS-IPP, AIPH, APG, MD *p=0.02 N=5482 UNCLASSIFIED 6

20. Relative Risk of Injury for Women and Men by Age in Basic Combat Training Source: Knapik, J et al. JSCR 23(3):685-697, 2009. Men n=2124 Women n=902 UNCLASSIFIED 19

21. Intrinsic Physical Fitness Risk Factors Health-related fitness Skill-related Fitness Cardiorespiratory endurance Muscular endurance Muscular strength Body composition Flexibility Agility Balance Coordination Speed Power Reaction time UNCLASSIFIED 20

22. IMAGE SOURCE: http://www.defenseimagery.mil/ 090818-A-AO884-339http://www.defenseimagery.mil/ UNCLASSIFIED 21

23. Injury Risks by Quartiles of Run Time for Female and Male Trainees N = 310 (186 women, 124 men)Source: Jones B et al Am J Sports Med, 1993 UNCLASSIFIED 22

24. Association of Initial Run Time and LE Overuse Injury * BCT RR Males: Q4/Q1 =2.81 p=<0.001; RR Females: Q4/Q1=2.03, p=<0.001 * Any LE overuse injury in the first 9 weeks of training IET, Ft Leonard Wood, 2002 UNCLASSIFIED 23

25. IMAGE SOURCE: http://www.defenseimagery.mil/ 110403-A-VF572-002http://www.defenseimagery.mil/ UNCLASSIFIED 24

26. Injury Risks by Push-Up Repetitions for Female and Male Trainees by Quartiles Knapik, USACHPPM Epicon Report No 29-HE-8370-99, 1999 N=692 Men, 398 Women; Risk Ratio (Q1/Q4): Men=1.4, Women=1.4 p-value for Trend: Men = 0.02, Women = 0.01 (Ft Jackson, 1998) UNCLASSIFIED 25

27. Injury Risks by Push-Up Quartiles for Women and Men in an Operational Unit Men n=2,530 Chi Square for Trend: p=<0.01 Women n=219 Chi Square for Trend: p=0.08 UNCLASSIFIED 26

28. Injury Risks for Female and Male Trainees by Quintiles of Body Mass Index (BMI) Source: Jones BH. Body Composition & Physical Performance. National Academy Press, pp 141-173, 1992. Ft. Jackson, 1988; Men n = 1053 Women n= 895, 8 weeks of training UNCLASSIFIED 27

29. Women Run Q1 (Fastest) Run Q2Run Q3Run Q4 Run Q5 (Slowest) Overall BMI Q1 (lowest) 29.238.945.349.363.141.9 BMI Q22635.840.247.75639.1 BMI Q324.633.938.346.655.439.5 BMI Q426.133.436.540.85639.6 BMI Q5 (highest) 2530.736.540.85441.2 Overall26.53539.344.656 Percent of Female Soldiers Injured by Run Time and BMI Quintile Source: DMSS, 2014. Prepared by Army Institute of Public Health, Injury Prevention Program N= 41,727 Trend of increased injury risk with decreased fitness. Significance: Run Q1, BMI Q3 << Run Q5, BMI Q1, RR=3.5; p < 0.001 UNCLASSIFIED 28

30. Incidence (%) of Women and Men in Army BCT with One or More Injury (2010 to 2012) Source: AIPH Analysis 2013 Gender Incidence/Risk of Injury Risk Ratio W/M (95% CI) Women39.7 %2.00 (2.00 - 2.10) Men19.4%1.00 N = 182,638 (155,670 men, 26,968 women) UNCLASSIFIED 29

31. Quintile (Run Time) MenWomen N% InjuredN (Fast) ≤14.336,44414.252633.5 14.4-15.435,25516.898130.1 15.5-16.534,45819.12,12128.7 16.6-18.330,366226,25833 (Slow) ≥18.319,14730.317,08244.2 Total155,67019.426,96839.7 Injury Risk for Women and Men in Basic Combat Training Stratified by Run Time RR (Unadjusted)2.0 (2.0-2.1) RR (Adjusted for Fitness)1.5 (1.4-1.5) Source: USAPHC injury analysis 2010-2012 UNCLASSIFIED 30

32. Risks of Injury for Women Compared to Men Length of Training (weeks) Study Year data Collected Recruits (n) Cumulative Injury Incidence (%) Risk Ratio WomenMenWomenMenWomen:Men 8 weeks Kowal et al. 1978 19787703476226.22.4 Bensel and Kisk 1983 19806441,84041.220.72.0 Jones et al. 1993 198418612450.527.41.8 Bell et al. 1993 198835250957272.1 Jones et al. 1996 19968415965.541.51.6 Knapik et al. 2001 19983056045830.81.9 9 weeks Canham- Chervak et al. 2000 199849865565.3302.2 Knapik et al. 2008 20079152,14764.736.91.8 Source: Knapik, J. et al. USAPHC Epidemiological Report #S.0007856-11, 2012 UNCLASSIFIED 31

33. WomenMen Age20 Height (cm)162175.1 Weight (kg)57.876.3 Body Fat (%)26.616.4 Initial 1-mile run (min) 10.17.6 Initial Sit-Ups (n)30.943.7 Initial Push-Ups (n)10.932.4 Injury Risk Ratio = 2.1 (1.78-2.5) Body Composition and Physical Fitness of Female and Male Army Basic Trainees Source: Bell NS, et al. Am J Prev Med. 18(3S):141-6, 2000. Men n=509, Women n=352 UNCLASSIFIED 32

34. Gender & Risk of ≥ 1 Training-Related Injury, Controlling for Fitness, Age & Race Risk FactorOR*95% CI Gender Men–– Women1.14(0.48-2.72) Run time Very Fast–– Fast1.47(0.68-3.18) Average1.54(0.91-2.62) Slow2.52(1.26-5.04) Very Slow3.23(1.59-6.58) Strength Very Strong–– Strong1.41(0.80-2.50) Average1.61(0.90-2.88) Weak2.1(0.88-5.04) Very Weak2.11(0.83-5.36) Age (yrs) < 20–– 20-241.5(1.00-2.23) 25 +1.26(0.69-2.31) *Multivariate logistic regression; other variables include SU, PU, Race Source: Bell NS, et al. Am J Prev Med. 18(3S):141-6, 2000. N= 861; 509 men, 352 women UNCLASSIFIED 33

35. Crude injury risk is greater for women than for men. Injury risk increases with increased activity Activities associated with injury risk are similar for men and women (physical-training related) Injury risk is highest at the lowest fitness levels for women and men. Conclusions Regarding Fitness and Injuries Among Women in the Army UNCLASSIFIED 34

36. There are some women in every level of fitness. On average, women’s fitness levels are lower than men’s. When corrected for fitness, women’s injury risks are similar to men’s Women with highest BMIs at each fitness level at lower risk of injury. Higher BMI or % body fat not as important as fitness for injury risk All conclusions need more research with focus on operational units. Conclusions Regarding Fitness and Injuries Among Women in the Army UNCLASSIFIED 34