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Table 2 Risk factors for injuries in female military personnel

From: Risk factors for injuries in female soldiers: a systematic review

References study type

Population

Risk factor

Key findings

 

Score* (%)

1. Altarac et al. [23] cohort study

915 female US Army recruits in 8-week basic training. Smoking history captured by self-reported survey prior to training, injuries collected via medical record review

Smoking in 1 month prior to enlisting

Smoking vs not smoking

 

92

   

Any injury

aOR 1.61 [95% CI = 1.19–2.17]

 
   

Traumatic

aOR 1.05 [95% CI = 0.67–1.64]

 
   

Overuse

aOR = 1.71 [95% CI = 1.26–2.31]

 
   

 ≥ 1 days lost injury

aOR = 1.44 [95% CI = 1.02–2.02]

 
   

 ≥ 6 days lost

aOR = 1.75 [95% CI = 1.21–2.51]

 

2. Anderson et al. [34] cross-sectional study

363 female enlisted US Army soldiers from two light infantry brigades. Data collected via self-reported survey over 12 months

Age

22–26 years (57% injured), 27–30 years (43% injured), ≥ 31 years (48% injured)

 

60

  

BF %

≤ 19.28%

REFERENCE

 
   

19.29–23.37%

RR = 0.74 [95% CI = 0.30–1.80]

 
   

≥ 23.38%

RR = 0.88 [95% CI = 0.53–1.47]

 
  

APFT push-ups

≥ 72 reps

REFERENCE

 
   

58–71 reps

RR = 1.05 [95% CI = 0.32–3.48]

 
   

≤ 57 reps

RR = 1.30 [95% CI = 0.44–3.82]

 
  

Sit-ups

≥ 74 reps

REFERENCE

 
   

63-73reps

RR = 1.09 [95% CI = 0.78–1.54]

 
   

≤ 62 reps

RR 1.35 [95% CI = 1.01–1.80] p = 0.03

 
  

2-mile run time

≤ 14.13 min

REFERENCE

 
   

14.14–15.67 min

RR = 0.92 [95% CI = 0.35–2.41]

 
   

≥ 15.68 min

RR = 1.32 [95% CI = 0.61–2.85]

 

3. Bedno et al. [3] cohort study

All 37,413 new enlisted female US Army soldiers from Jan 2011–Jan 2014 (lower extremity ICD = 9 musculoskeletal injuries captured from inpatient or outpatient visits)

Age

17–23 years

REF

83

   

24–28 years

OR = 1.05 [1.01–1.10] p = 0.008

 
   

29–35 years

OR = 1.18 [1.11–1.26] p < 0.001

 
   

≥ 36 years

OR = 1.47 [1.27–1.69] p < 0.001

 
  

BMI

Normal

REFERENCE

 
   

Underweight

OR = 1.16 [0.99–1.36] p = 0.07

 
   

Overweight

OR = 1.04 [1.00–1.08] p = 0.09

 
   

Obese

OR = 1.03 [0.90–1.18] p = 0.68

 
  

APFT

 > 270

REFERENCE

 
   

240–269

OR = 1.11 [95% CI = 1.03–1.20] p = 0.006

 
   

215–239

OR = 1.17 [95% CI = 1.09–1.27] p < 0.001

 
   

 < 215

OR = 1.45 [95% CI = 1.35–1.57] p < 0.001

 
  

Current smoking (Y/N)

(Y)

OR = 1.30 [1.23–1.36]

 
  

Deployment

none

REFERENCE

 
   

1

OR = 0.65 [95% CI = 0.58–0.72] p < 0.001

 
   

2

OR 0.73 [95% CI = 0.43–1.25] p = 0.258

 

4. Bijur et al. [9] cohort study

85 female West Point Cadets. Data collected via medical records

Height

N/S

 

92

  

Mean Run time per mile

7.2 min 42.1 injuries /100 cadets, 8.1 min 66.7 injuries /100 cadets, 8.7 min 76.2 injuries /100 cadets, 9.8 min 126.3 injuries/100 cadets

  

5. Grier et al. [24] cohort study

3856 women prior to ordinance AIT after recently finishing BCT. All data collected via self-reported survey

Age

17–19 years

REFERENCE

70

   

20–24 years

OR = 1.29 [95% CI = 1.07–1.56]

 
   

25–29years

OR = 1.29 [95% CI = 0.96–1.74]

 
   

≥ 30 years

OR = 2.02 [95% CI = 1.43–2.87]

 
  

Smoking

Non-smokers

REFERENCE

 
   

Occasional

OR = 1.01 [95% CI = 0.74–1.39] p = 0.95

 
   

Frequent

OR = 0.96 [95% CI = 0.80–1.15] p = 0.65

 
  

Number of Cigarettes

None

REFERENCE

 
   

≤ 10

OR = 1.04 [95% CI = 0.80–1.34] p = 0.77

 
   

20-Oct

OR = 0.91 [95% CI = 0.71–1.18] p = 0.48

 
   

> 20

OR = 0.89 [95% CI = 0.61–1.30] p = 0.55

 

6. Grier et al. [35] cross-sectional study

498 Women at US Army Ordinance School. Physical performance data collected via military records; injuries collected via self-reported survey

Age

17–19 years

REFERENCE

83

   

20–24 years

HR = 0.89 [95% CI = 0.68–1.16) p = 0.39

 
   

25+ years

HR = 1.18 [95% CI = 0.86–1.63] p = 0.32

 
  

Smoking

Non-smokers

REFERENCE

 
   

Occasional

HR = 1.08 [95% CI = 0.67–1.73] p = 0.77

 
   

Frequent

HR = 1.27 [95% CI = 0.98–1.63] p = 0.07

 
  

Number of Cigarettes

None

REFERENCE

 
   

 ≤ 10

HR = 1.03 [95% CI = 0.71–1.49] p = 0.89

 
   

20-Oct

HR = 1.37 [95% CI = 0.95–1.97] p = 0.09

 
   

 > 20

HR = 1.71 [95% CI = 1.12–2.59] p = 0.01

 
  

Injury (Y/N)

Y

HR = 1.67 [95% CI = 1.21–2.30] p < 0.01

 
  

Push-ups

0–23 reps

HR = 1.47 [95% CI = 1.03–2.09] p = 0.03

 
   

24–30 reps

HR = 1.44 [95% CI = 1.02–2.04] p = 0.04

 
   

31–36 reps

HR = 1.04 [95% CI = 0.71–1.53] p = 0.84

 
   

37 + reps

REFERENCE

 
  

Sit-ups

0–53 reps

HR = 1.28 [95% CI = 0.91–1.76] p = 0.16

 
   

54–60 reps

HR = 1.17 [95% CI = 0.83–1.66] p = 0.36

 
   

61–67 reps

HR = 1.04 [95% CI = 0.73–1.48] p = 0.82

 
   

68 + reps

REFERENCE

 
  

2 Mile Run

0–17.00 min

REFERENCE

 
   

17.01–18.08 min

HR = 1.46 [95% CI = 1.02–2.08] p = 0.04

 
   

18.09–19.38 min

HR = 1.27 [95% CI = 0.88–1.83] p = 0.21

 
   

19.39 + mins

HR = 2.04 [95% CI = 1.45–2.88] p < 0.01

 

7. Heller et al. [25] cohort study

227 British Army basic training recruits. Run times collected via military records, injuries collected via medical records

1.5 mile run time

Mean injury free time = 12min13sec, Mean Injured time = 12min43sec, Every 10 s increase in time = 8.3% greater injury risk

 

75

8. Henderson et al. [36] cross-sectional study

287 US Combat Medic Trainees. Previous injury, smoking and activity collected via self-reported survey; all other data collected via medical records

Age

< 20 years Injury Incidence 31.2%

REFERENCE

75

   

20–25 years Injury Incidence 21.3%

aOR = 0.7 [95% CI = 0.4–1.3]

 
   

> 25 years Injury Incidence 52.9%

aOR = 3.5 [95% CI = 1.5–8.1]

 
  

Previous Injury

Y Injury incidence 29.5%, N Injury Incidence 37.4%

  
  

BMI

17.5–21.0 kg/m2 Injury Incidence 22.1%

  
   

22.0–23.5 kg/m2 Injury Incidence 29.0%

  
   

23.6–25.3 kg/m2 Injury Incidence 27.9%

  
   

25.4–31.2 kg/m2 Injury Incidence 36.8%

  
   

n/s p = 0.305

  
  

Body Mass

46-57 kg Injury Incidence 22.4%

REFERENCE

 
   

58-63 kg Injury Incidence 30.9%

aOR = 1.5 [95% CI = 0.7–2.3]

 
   

64-68 kg Injury Incidence 22.2%

aOR = 1.1 [95% CI = 0.5–2.5]

 
   

69-95 kg Injury Incidence 41.8%

aOR = 2.4 [95% CI = 1.1–5.0]

 
  

Smoking (Y/N)

   
  

Activity Prior to BCT

   
  

Frequency of Activity prior to BCT

Yes—Injury Incidence 23.6%, No—Injury Incidence 31.8% (n/s p = 0.190)

  
   

More than most—Injury Incidence 41.9%, Somewhat more than most—Injury Incidence 25.6%, as active as most—Injury Incidence 29.5%, Less active than most—Injury Incidence 25.0% (p = 0.243)

  
   

0/week—Injury Incidence 36.4%

  
   

1–2/week– Injury Incidence 25.3%

  
   

3–4/week– Injury Incidence 31.0%

  
   

5–7/week– Injury Incidence 30.9% (p = 0.623)

  

9. Jones et al. [26] cohort study

186 women Army trainees during basic training. Previous activity self-reported via survey, all other data via medical records,

Height

Shorter 25% women at greater risk than taller 75%

RR 1.7 [95% CI = 1.2–2.4] p = 0.02

83

  

Body Fat %

N/S

  
  

Body mass

N/S

  
  

BMI

N/S

  
  

Push-ups

N/S

  
  

Sit-ups

N/S

  
  

Self-reported previous activity

N/S

  
  

Run Time

Q1

RR = 1.16 [95% CI = 0.5–2.7]

 
   

Q2

RR = 1.0

 
   

Q3

RR = 2.40 [95% CI = 1.2–4.8] p = 0.028

 
   

Q4

RR = 2.18 [95% CI = 1.1–5.0] p = 0.063

 
  

Slow vs Fast Runners

Any injury

RR = 1.69 [95% CI = 1.2–2.4] p = 0.004

 
   

Lower body injury

RR = 1.78 [95% CI = 1.2–2.6] p = 0.004

 
   

Time loss injury

RR = 2.12 [95% CI = 1.2–3.7] p = 0.0007

 
   

Stress Fracture

RR = 2.54 [95% CI = 1.0–6.6] p = 0.05

 

10. Jones et al. [27] cohort study

41 727 women in US Army Basic Training. Data collected via military database; injuries collected via surveillance system

2-mile Run time

Q1 (Fastest) injury risk = 26.5%

REFERENCE

83

   

Q2 Injury risk = 35%

RR = 1.3 [95% CI = 1.3–1.4]

 
   

Q3 Injury risk = 39.3%

RR = 1.5 [95% CI = 1.4–1.5]

 
   

Q4 Injury risk = 44.6%

RR = 1.7 [95% CI = 1.6–1.8]

 
   

Q5 (Slowest) Injury risk = 56.0%

RR = 2.1 [95% CI = 2.0–2.2]

 
  

BMI

Q1 (Lowest) Injury risk = 41.9%

RR = 1.1 [95% CI = 1.02–1.1]

 
   

Q2 Injury risk = 39.1%

RR = 1.0 [95% CI = 0.9–1.0]

 
   

Q3 Injury risk = 39.5%

REFERENCE

 
   

Q4 Injury risk = 39.6%

RR = 1.0 [95% CI = 0.9–1.1]

 
   

Q5 (Highest) Injury risk = 41.2%

RR = 1.04 [95% CI = 1.01–1.08]

 
  

Slow run time and low BMI

Injury risk 63.1%

RR = 2.6 [95% CI = 2.3–2.8], p < 0.00001

 
  

Push-ups

Low vs High 48.8% to 31.6%

RR = 1.5 [95% CI = 1.49–1.61] p < 0.00001

 
  

Low BMI & Low Push-ups

Injury risk 50%

RR = 1.7 [95% CI = 1.6–1.9]

 

11. Knapik et al. [28] cohort study

474 women in US Army Basic Training. Smoking and physical activity history self-reported, all other data collected via medical records

Age

17–20 years

REFERENCE

92

   

20–25 years

RR = 1.0 [95% CI = 0.8–1.3]

 
   

25–35 years

RR = 1.3 [95% CI = 0.9–1.9]

 
  

Height

58–62in

REFERENCE

 
   

63–64in

RR = 1.0 [95% CI = 0.7–1.4] p = 0.89

 
   

65–66in

RR = 1.3 [95% CI = 0.9–1.9] p = 0.22

 
   

67–74in

RR = 1.0 [95% CI = 0.7–0.4] p = 0.85

 
  

Mass

90–119lbs

REFERENCE

 
   

120–134lbs

RR = 1.0 [95% CI = 0.7–1.4] p = 0.93

 
   

135–150lbs

RR = 1.0 [95% CI = 0.7–1.5] p = 0.84

 
   

151–239lbs

RR = 1.1 [95% CI = 0.8–1.6] p = 0.47

 
  

BMI

15.81–20.54 m/kg2

REFERENCE

 
   

20.55–22.98 m/kg2

RR = 1.3[95% CI = 0.9–1.9] p = 0.15

 
   

22.99–25.01 m/kg2

RR = 0.9 [95% CI = 0.7–1.4] p = 0.78

 
   

25.02–33.21 m/kg2

RR = 1.3 [95% CI = 0.9–1.9] p = 0.10

 
  

3.2 km Run time

13.00–19.48 min

REFERENCE

 
   

19.49–21.65 min

RR = 1.5 [95% CI = 1.0–2.3] p = 0.06

 
   

21.66–23.48 min

RR = 1.6 [95% CI = 1.0–2.3] p = 0.04

 
   

23.49–28.68 min

RR = 1.9 [95% CI = 1.2–2.8] p < 0.01

 
  

Push-ups

0–2 reps

RR = 1.6 [95% CI = 1.1–2.5] p = 0.02

 
   

3–5 reps

RR = 1.6 [95% CI = 1.1–2.3] p = 0.02

 
   

6–13 reps

RR = 1.6 [95% CI = 1.1–2.4] p = 0.02

 
   

14–50 reps

REFERENCE

 
  

Sit-ups

0–22 reps

RR = 1.3 [95% CI = 0.9–2.0] p = 0.14

 
   

23–33 reps

RR = 1.2 [95% CI = 0.8–1.8] p = 0.29

 
   

34–44 reps

RR = 1.1 [95% CI = 0.7–1.6] p = 0.66

 
   

45–80 reps

REFERENCE

 
  

Smoking (Y/N)

Y

RR = 2.0 [95% CI = 12–3.5] p = 0.01

 
   

 > 20 Cigarettes/day

RR = 1.4 [95% CI = 1.9–10.0] p < 0.01

 
  

VO2max

29.9–37.0 ml/kg/min

RR = 2.8 [95% CI = 1.4–5.6] p < 0.01

 

12. Knapik et al. [29] cohort Study

451 women in US Army Basic Training. Smoking, injury, and activity history collected via self-reported survey; injuries collected via surveillance system

Age

17.0–19.9 years

REFERENCE

100

   

20.0–24.9 years

HR = 1.02 [95% CI = 0.85–1.23] p = 0.84

 
   

25.0–29.9 years

HR = 1.30 [95% CI = 1.01–1.66] p = 0.04

 
   

≥ 30 years

HR = 1.43 [95% CI = 1.12–1.84] p < 0.01

 
  

Previous injury (Y/N)

(Y)

HR = 1.41 [95% CI = 1.13–1.75] p < 0.01

 
  

BMI

15.20–22.12 kg/m2

REFERENCE

 
   

21.30–23.80 kg/m2

HR = 0.89 [95% CI = 0.71–1.11] p = 0.30

 
   

23.81–25.97 kg/m2

HR = 0.91 [95% CI = 0.73–1.13] p = 0.40

 
   

25.98–34.02 kg/m2

HR = 0.89 [95% CI = 0.71–1.11] p = 0.28

 
  

Push-ups

0–4 reps

HR = 1.92 [95% CI = 1.41–2.59] p < 0.01

 
   

5–13 reps

HR = 1.36 [95% CI = 0.99–1.86] p = 0.06

 
   

14–22 reps

HR = 1.20 [95% CI = 0.87–1.65] p = 0.27

 
   

23–62 reps

REFERENCE

 
  

Sit-ups

0–20 reps

HR = 1.75 [95% CI = 1.29–2.37] p < 0.01

 
   

21–33 reps

HR = 1.34 [95% CI = 0.98–1.83] p = 0.07

 
   

34–46 reps

HR = 1.10 [95% CI = 0.79–1.51] p = 0.58

 
   

47–89 reps

REFERENCE

 
  

2 Mile Run

12.3–19.4 min

REFERENCE

 
   

19.5–22.1 min

HR = 0.99 [95% CI = 0.71–1.38] p = 0.94

 
   

22.2–24.7 min

HR = 1.14 [95% CI = 0.82–1.59] p = 0.43

 
   

24.8–31.3 min

HR = 2.18 [95% CI = 1.60–2.98] p < 0.01

 
  

Smoking

0

REFERENCE

 
   

1–9/day

HR = 1.44 [95% CI = 1.19–1.73] p < 0.01

 
   

10–19/day

HR = 1.47 [95% CI = 1.17–1.89] p < 0.01

 
   

≥ 20/day

HR = 1.90 [95% CI = 1.34–2.68] p < 0.01

 
  

Frequency of ex before BCT

≤ 1/week

HR 1.41 [95% CI = 1.09–1.82p p < 0.01

 
  

Frequency of running before BCT

≤ 1/week

HR = 1.62 [95% CI = 1.16–2.27] p < 0.01

 

13. Kodesh et al. [30] cohort study

158 females on IDF Combat Fitness Instructor Course. All data collected via medical records

Power Performance including 10 m sprint, single leg triple hop drop jump, CMJ

All power tests n/s except, L triple hop (cm) 418 (254–559) vs 446.5 (199–584) p = 0.029, R triple hop distance (cm) 434 (287–536) vs 460 (263–546) p = 0.047)

 

67

  

Body Fat %

BF% 23.7 (20.5–29.2) vs 22.5 (14.9–31.5) p = 0.047

  
  

BMI

BMI 21.14 [18.06–25.79) injured vs 20.70 [16.16–32.03] not injured

  
  

FMS

FMS n/s

  
  

2 km Run

258 (578–776) sec vs 640 (488–804) sec p = 0.044

  

14. Krauss et al. [31] cohort study

1900 US Army recruits during first 183 days of service from six locations in the US. Data collected via military and medical records

Fit vs unfit

Non stress fracture

IRR = 1.32 [95% CI = 1.14–1.53]

75

   

Stress fracture

IRR = 1.62 [95% CI = 1.19–2.21]

 
   

Non stress fracture

IRR = 1.27 [95% CI = 1.07–1.50]

 
  

Fit (high % BF vs low % BF)

Stress fracture

IRR = 0.79 [95% CI = 0.49–1.28]

 

15. Rappole et al. [1] cohort study

369 US female Army Soldiers from Combat Arms, Combat Support and Combat Service Support. Injury data collected via medical records, other data via self-reported survey

Age

n/s

 

67

  

2-mile run

n/s

  
  

Push-ups

n/s

  
  

Sit-ups

n/s (at 0.05)

  
  

Unit PT resistance training

≥ 1/week

OR 1.96 [95% CI = 1.20–3.21] p < 0.01

 
  

Personal PT run distance

> 1 mile

OR 1.57 [95% CI = 0.98–2.52] p = 0.06

 
  

Personal PT interval freq

None/ < 1/week

OR 1.64 [95% CI = 1.00–2.71] p = 0.05

 

16. Roy et al. [2] cohort study

625 US Army female soldiers within three brigade combat teams Injuries collected via self-reported survey

Deployment

0

RR = 1.48 [95% CI = 1.02–1.71]

75

   

1

RR = 1.22 [95% CI = 0.84–1.78]

 
   

≥ 2

REFERENCE

 
  

Injury History (Y/N)

(Y)

RR = 2.6 [95% CI = 2.06–3.28]

 
  

2-mile Run time

≤ 17 min

REFERENCE

 
   

17.01–18.0

RR = 1.71 [95% CI = 1.07–2.73]

 
   

> 18 min

RR = 1.41 [95% CI = 0.90–2.19]

 
  

Unit Runs/week

0

RR = 1.526 [95% CI = 1.07–2.19]

 
  

Pers. PT/week

0

REFERENCE

 
   

2-Jan

RR = 1.42 [95% CI = 1.08–1.87]

 
   

≥ 3

RR = 1.31 [95% CI = 0.94–1.83]

 
  

APFT score

< 220

RR = 1.74 [95% CI = 1.01–3.02]

 
   

220–249

RR = 2.01 [95% CI = 1.19–3.38]

 
   

250–289

RR = 1.7 [95% CI = 1.02–2.86]

 
   

≥ 290

REFERENCE

 

17. Roy et al. [32] cohort study

57 female soldiers from US infantry or support battalions on deployment in Afghanistan in 2012. Data collected by self-reported survey

Work type

Physically demanding

RR = 6.0 [95% CI = 1.50–23.99]

67

  

Miles walked/day

> 4

RR = 3.0 [95% CI = 1.52–5.93]

 
  

Avg worn load

> 30 lb

RR = 2.44 [95% CI = 1.7–4.36]

 
  

Weight of avg lifted object

> 50 lb

RR = 2.3 [95% CI = 1.19–4.45]

 

18. Roy et al. [33] cohort study

160 female soldiers from three brigade combat teams deployed to Afghanistan for nine months. Data collected via self-reported survey

Wearing load

> 10% body weight

RR = 2.0 [95% CI = 1.31–3.06]

100

   

Heaviest load > 15%

RR = 5.83 [95% CI = 1.51–22.50]

 
  

Wearing armour

1–4 h

RR = 1.62 [95% CI = 1.002–2.62]

 
   

> 4 h

RR = 1.84 [95% CI = 1.03–3.27]

 
  

Wearing backpack

Y

RR = 1.85 [95% CI = 1.23–2.80]

 
  

Occupational tasks

Lifting > 22.68 kg

RR = 1.96 [95% CI = 1.08–2.97]

 
   

Lifting objects 1–2 × day

RR = 1.73 [95% CI = 1.002–2.97]

 
   

Carrying objects > 7.62 m

RR = 2.01 [95% CI = 1.19–3.42]

 
  

Y balance score

< 95.23

RR = 1.71 [95% CI = 1.13–2.60]

 
  1. Bold indicates significant risk factors
  2. RR = Relative Risk, OR = Odds Ratio, IRR = Incident Rate Ratio, HR = Hazard Ratio, 95% CI = 95% Confidence Interval, n/s = not significant, in = inches
  3. *Methodological Quality Score