Table 2.
Participant characteristics by injury status
| Overall (n = 201) | Non-BSI (n = 181) | BSI (n = 20) | p | |
|---|---|---|---|---|
| Demographics | ||||
| Regiment | ||||
| Line Infantry | 137 (100.0%) | 131 (95.6%) | 6 (4.4%) | < 0.001* |
| Parachute | 64 (100.0%) | 50 (78.1.6%) | 14 (21.9%) | |
| Alcohol Intakea | ||||
| Zero Intake | 18 (100.0%) | 17 (94.4%) | 1 (5.6%) | 0.651 |
| Light (1–90 units per month) | 124 (100.0%) | 112 (90.3%) | 12 (9.7%) | |
| Heavy (91–300 units per month) | 47 (100.0%) | 40 (85.1%) | 7 (14.9%) | |
| Very Heavy (> 300 units per month) | 1 (100.0%) | 1 (100.0%) | 0 | |
| Smokingb | 0.412 | |||
| Never Smoked | 76 (100.0%) | 69 (39.4%) | 7 (35.0%) | |
| Previous Smoker | 54 (100.0%) | 60 (34.3%) | 5 (25.0%) | |
| Current Smoker | 65 (100.0%) | 46 (26.3%) | 8 (40.0%) | |
| Ethnicityc | 0.657 | |||
| Asian | 2 (100.0%) | 2 (100.0%) | 0 | |
| Black | 3 (100.0%) | 3 (100.0%) | 0 | |
| Mixed | 3 (100.0%) | 2 (66.7%) | 1 (33.3%) | |
| White | 187 (100.0%) | 168 (89.8%) | 19 (10.2%) | |
| Other | 1 (100.0%) | 1 (100.0%) | 0 | |
| Age at Start of Basic Military Training (years) | 20.7 [4.3] | 20.7 [4.1] | 22.9 [5.0] | 0.264 |
| Body Composition and Physical Performance | ||||
| Height (cm) | 177.7 ± 6.2 | 177.7 ± 6.2 | 177.7 ± 5.7 | 0.486 |
| Body Mass Index (kg/m2) | 24.0 ± 2.7 | 24.1 ± 2.8 | 23.1 ± 2.0 | 0.112 |
| Total Body Mass (kg) | 76.0 ± 10.1 | 73.0 ± 8.6 | 76.3 ± 10.2 | 0.129 |
| Lean Body Mass (kg)e | 57.2 [6.8] | 58.0 [7.0] | 54.7 [4.1] | 0.098 |
| Leg aBMD (g∙cm2)e | 1.36 ± 0.13 | 1.36 ± 0.13 | 1.34 ± 0.14 | 0.441 |
| 2.4 km run time (s)f | 597 [91] | 598 [89] | 568 [86] | 0.130 |
| Maximum Dynamic Lift (kg)g | 73 [20] | 75 [20] | 70 [19] | 0.414 |
| Peak Power Output (W)h | 3940 ± 540 | 3969 ± 536 | 3731 ± 532 | 0.083 |
| Biochemistry | ||||
| Total 25(OH)D (nmol·L−1) | 58.3 [43.2] | 57.5 [42.9] | 61.0 [49.3] | 0.389 |
| PTH (pmol·L−1)d | 3.50 [1.51] | 3.47 [1.62] | 3.77 [1.39] | 0.168 |
| Adjusted Calcium (mmol·L−1) | 2.39 [0.09] | 2.39 [0.09] | 2.40 [0.12] | 0.390 |
| Iron (µmol·L−1) | 20.3 [8.5] | 20.5 [8.5] | 19.5 [11.7] | 0.327 |
| P1NP (µg∙L)d | 92.8 [45.2] | 92.8 [45.2] | 97.0 [48.7] | 0.650 |
| CTX (µg∙L)d | 0.47 [0.22] | 0.47 [0.22] | 0.43 [0.20] | 0.175 |
| Bone Parameters | ||||
| Total vBMD (mg HA·cm3) | 350 ± 50 | 351 ± 50 | 338 ± 48.0 | 0.280 |
| Trabecular vBMD (mg HA·cm3) | 231 ± 33 | 232 ± 32 | 223 ± 37 | 0.206 |
| Total Area (mm2) | 840 [188] | 846 [194] | 791 [165] | 0.160 |
| Trabecular Area (mm2) | 690 [205] | 794 [207] | 647 [172] | 0.364 |
| Cortical vBMD (mg HA·cm3) | 889 [47] | 891 [29] | 896 [60] | 0.903 |
| Trabecular Number (1·mm) | 2.20 ± 0.29 | 2.21 ± 0.28 | 2.12 ± 0.35 | 0.192 |
| Trabecular Thickness (mm) | 0.09 ± 0.01 | 0.09 ± 0.01 | 0.09 ± 0.01 | 0.946 |
| Trabecular Spacing (mm) | 0.364 [0.073] | 0.361 [0.069] | 0.369 [0.116] | 0.237 |
| Cortical Area (mm2) | 140 ± 21 | 141 ± 21 | 130 ± 17 | 0.029* |
| Cortical Perimeter (mm) | 113.9 [12.7] | 114.2 [12.7] | 110.3 [11.0] | 0.096 |
| Cortical Porosity (%) | 5 [2] | 5 [2] | 4 [2] | 0.217 |
| Cortical Thickness (mm) | 1.32 ± 0.24 | 1.33 ± 0.25 | 1.26 ± 0.19 | 0.205 |
| Cortical Pore Diameter (mm) | 0.161 [0.022] | 0.160 [0.021] | 0.167 [0.026] | 0.688 |
| Stiffness (kN∙mm) | 284.0 ± 41.18 | 286.4 ± 40.71 | 262.08 ± 39.9 | 0.012* |
| Estimated Failure Load (kN) | -14.2 ± 2.0 | -14.3 ± 2.0 | -13.1 ± 1.9 | 0.011* |
Categorical data are presented as total (percentage) with p-values calculated by Chi-Squared. Continuous data are mean ± SD with p-values from independent t-tests or median [IQR] with p-values from Mann–Whitney U Tests
aoverall n = 190, non-BSI n = 170
boverall n = 195, non-BSI n = 175
coverall n = 196, non-BSI n = 176
doverall n = 200, non-BSI n = 180
eoverall n = 192, non-BSI n = 173, BSI n = 19
foverall n = 160, non-BSI n = 143, BSI n = 17
goverall n = 144, non-BSI n = 128, BSI n = 16
hoverall n = 149, non-BSI n = 131, BSI n = 18