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A Simplified Model to Predict Stress Fracture in Young Elite Combat Recruits

Moran, Daniel S.1,2; Finestone, Aharon S.3; Arbel, Yael1; Shabshin, Nogah4; Laor, Arie1

The Journal of Strength & Conditioning Research: September 2012 - Volume 26 - Issue 9 - p 2585–2592
doi: 10.1519/JSC.0b013e31823f2733
Original Research

Moran, DS, Finestone, AS, Arbel, Y, Shabshin, N, and Laor, A. A simplified model to predict stress fracture in young elite combat recruits. J Strength Cond Res 26(9): 2585–2592, 2012—The purpose of the study was to develop a simple prediction model for stress fractures (SFs) in young male recruits to identify risk factors for SF. Data were collected from 57 young (18.5 ± 0.5 years) male athletes before elite combat basic training (BT). Measurements included anthropometric variables, blood samples, fitness tests, bone quality (peripheral quantitative computed tomography [pQCT]), psychological assessment, nutritional habits, and history of physical activity. A medical evaluation was done periodically. The SFs were clinically diagnosed during the 1-year training and thereafter confirmed by bone scintigraphy. Three “simple to monitor” variables were found to be significantly (p < 0.05) related to SF occurrence during basic and advanced training: aerobic training frequency, aerobic training duration, and waist circumference. From these 3 variables, a new model was constructed that successfully predicted 85% of the soldiers with (n = 23) and without (n = 34) SF as follows:



where PSF is the stress fracture prediction according to the Log Odds (SF), Odds(SF) is the ratio between the probability of SF existence and nonexistence, ATn is the aerobic training (times per week), ATt is the aerobic training duration (minutes per week), and waist is the circumference (centimeters). This model was validated on a different database taken from another 59 elite combat recruits before BT and successfully predicted 76.5% of the soldiers with SF (n = 22) and without SF (n = 37). A young male recruit for elite combat unit is at a greater risk of developing SF if, before entering BT, he trained aerobically <2 times per week with each training >40 minutes and has a waist circumference of <75 cm. However, further evaluation is required for different combat recruits, ages, and training programs to validate these results.

1Heller Institute of Medical Research, Sheba Medical Center, Tel Hashomer, Israel

2Ariel University, Center of Samaria, Ariel, Israel

3Department of Orthopaedics, Assaf Harofeh Medical Center, Zeriffin, Israel

4Department of Diagnostic Imaging, Sheba Medical Center, Tel Hashomer, Israel

Address correspondence to Dr. Daniel S. Moran,

© 2012 National Strength and Conditioning Association