Stress fractures in the lower extremities of soldiers in basic training.

In a 4-year study on stress fractures of the lower extremities in basic-training soldiers at Fort Dix, New Jersey, 1,338 stress fractures were confirmed in 1,050 soldiers from a total training population of 109,296, for an incidence of 0.96%. There were 691 men with stress fractures from a male training population of 76,237 (0.91%), and 359 women with stress fractures from a female training population of 33,059 (1.09%), with significant sexual differences in the anatomic distribution of fractures as well. Common male stress-fracture sites were the metatarsals (66%), calcaneus (20%), and lower leg (13%). Common female stress-fracture sites were the calcaneus (39%), metatarsals (31%), and lower leg (27%). Female soldiers suffered more than twice the number of bilateral stress fractures than men. The week of onset of stress fractures during basic training varied directly with the sex of the soldier. Modifications in the physical training program aimed at eliminating continuous, high-impact activities during high-risk weeks resulted in a 12.73% drop in stress-fracture incidence (decreases of 7.32% in women and 16.19% in men).