Table 4.
Baseline demographics, alcohol intake, smoking status and ethnicity of participants undergoing parachute regiment training
| Overall (n = 64) | Non-BSI (n = 50) | BSI (n = 14) | P | |
|---|---|---|---|---|
| Demographics | ||||
| Alcohol Intake | ||||
| Zero Intake | 4 (6.3%) | 4 (8%) | 0 | 0.089 |
| Light (1–90 units per month) | 42 (65.6%) | 35 (70%) | 7 (50%) | |
| Heavy (91–300 units per month | 18 (28.1%) | 11 (22%) | 07 (50%) | |
| Very Heavy (> 300 units per month) | 0 | |||
| Smoking | ||||
| Never Smoked | 31 (48.4%) | 24 (48%) | 7 (50%) | |
| Previous Smoker | 28 (43.8%) | 21 (42%) | 7 (50%) | 0.456 |
| Current Smoker | 5 (7.8%) | 5 (10%) | 0 | |
| Ethnicity | ||||
| Asian | 2 (3.1%) | 2 (4%) | 0 | 0.644 |
| Black | 1 (1.6%) | 1 (2%) | 0 | |
| White | 61 (95.3%) | 47 (94%) | 14 (93.3%) | |
| Age at Start of Military Training (years) | 21.61 [4.86] | 21.33 [4.76] | 22.63 [5.29] | 0.697 |
| Body Composition and Physical Performance | ||||
| Height (cm) | 177.3 ± 6.2 | 177.4 ± 6.5 | 176.9 ± 5.2 | 0.400 |
| Body Mass Index (kg/m2) | 24.0 ± 2.3 | 24.3 ± 2.4 | 23.0 ± 1.8 | 0.059 |
| Total Body Mass (kg) | 75.7 ± 9.5 | 72.2 ± 9.0 | 76.7 ± 9.5 | 0.123 |
| Total Lean Mass (kg)a | 59.1 ± 6.3 | 60.1 ± 6.6 | 55.6 ± 3.7 | 0.025* |
| Leg aBMD (g/cm2)a | 1.39 [0.21] | 1.41 [0.22] | 1.27 [0.17] | 0.012* |
| 2.4-km Run Time (secs)b | 551 [30] | 547 [47] | 552 [30] | 0.296 |
| Maximum Lift (kg)c | 75.0 [15] | 75 [18] | 74 [15] | 0.338 |
| Peak Power Output (W)d | 4005 ± 559 | 4081 ± 549 | 3790 ± 555 | 0.122 |
| Biochemistry | ||||
| Total 25(OH)D (nmol·L−1) | 69.0 ± 25.9 | 68.6 ± 25.9 | 70.5 ± 26.8 | 0.565 |
| PTH (pmol·L−1)e | 3.83 ± 1.22 | 3.84 ± 1.32 | 3.82 ± 0.81 | 0.964 |
| Adjusted Calcium (mmol·L−1) | 2.37 ± 0.07 | 2.36 ± 0.07 | 2.38 ± 0.07 | 0.264 |
| Iron (µmol·L−1) | 20.5 ± 7.4 | 20.7 ± 7.3 | 20.1 ± 7.9 | 0.792 |
| P1NP (µg/L)f | 93.5 [51.8] | 93.5 [51.2] | 96.6 [55.6] | 0.791 |
| CTX (µg/L)f | 0.45 [0.19] | 0.45 [0.18] | 0.46 [0.25] | 0.710 |
| Bone parameters | ||||
| Total vBMD (mg HA·cm3) | 353 ± 52 | 3547 ± 53 | 349 ± 50.0 | 0.744 |
| Trabecular vBMD (mg HA•cm3) | 232 ± 38 | 233 ± 38 | 229 ± 38 | 0.691 |
| Total Area (mm2) | 850 ± 127 | 8638 ± 129 | 802 ± 107 | 0.114 |
| Trabecular Area (mm2) | 697 ± 128 | 708 ± 131 | 660 ± 111 | 0.212 |
| Cortical vBMD (mg HA·cm3) | 888 [52] | 888 [47] | 893 [64] | 0.826 |
| Trabecular Number (1·mm) | 2.13 ± 0.40 | 2.25 ± 0.30 | 2.13 ± 0.40 | 0.227 |
| Trabecular Thickness (mm) | 0.087 ± 0.013 | 0.087 ± 0.013 | 0.090 ± 0.010 | 0.351 |
| Trabecular Spacing (mm) | 0.36 [0.08] | 0.353 [0.73] | 0.37 [0.10] | 0.363 |
| Cortical Area (mm2) | 143 ± 20 | 145 ± 20 | 134 ± 17 | 0.075 |
| Cortical Perimeter (mm) | 114.1 [13.3] | 115.9 [12.6] | 109.7 [11.2] | 0.077 |
| Cortical Porosity (%) | 5 ± 2 | 5 ± 2 | 5 ± 2 | 0.645 |
| Cortical Thickness (mm) | 1.35 ± 0.22 | 1.36 ± 0.22 | 1.31 ± 0.19 | 0.401 |
| Cortical Pore Diameter (mm) | 0.161 [0.019] | 0.159 [0.019] | 0.169 [0.019] | 0.121 |
| Stiffness (kN∙mm) | 283.72 ± 47.76 | 288.58 ± 48.86 | 266.37 ± 40.55 | 0.125 |
| Estimated Failure Load (kN) | −14.19 ± 2.31 | −14.44 ± 2.38 | −13.31 ± 1.88 | 0.108 |
Categorical data are presented as total (percentage), p-values calculated by Chi Squared. Continuous data are mean ± SD, p-value calculated by independent samples t-tests or median [IQR], p-value calculated by Mann–Whitney U Test
aoverall n = 58, non-BSI n = 45, BSI n = 13
boverall n = 52, non-BSI n = 40, BSI n = 13
coverall n = 43, non-BSI n = 33, BSI n = 10
doverall n = 46, non-BSI n = 34, BSI n = 12
eoverall n = 53, non-BSI n = 49
foverall n = 63, non-BSI n = 49