Use of simple measures of physical activity to predict stress fractures inyoung men undergoing a rigorous physical training program

Among a population of randomly selected US Marine Corps recruits at Marine Corps Recruit Depot, San Diego, California, the authors developed a screeni ng tool to identify individuals at high risk for lower extremity stress fra cture when beginning a rigorous physical training program. The screening to ol was developed among 1,286 recruits, then tested and refined among 1,078 additional recruits. The refined algorithm, consisting of five physical act ivity questions and a 1.5-mi (2.4-km) run time, revealed that 21.6% of "hig h risk" subjects suffered more than three times as many stress fractures as "low risk" subjects. These data suggest that risk of stress fracture durin g rigorous physical training is increased by poor physical fitness and low levels of physical activity prior to their entry into the program.