However, the muscles, usually those in the lower leg, become fatigued after running a long distance and lose their ability to absorb shock. As the bones now experience larger stresses, this increases the risk of fracture. Previous stress fractures have been identified as a risk factor. Along with history of stress fractures, a narrow tibial shaft, high degree of hip external rotation, osteopenia, osteoporosis, and pes cavus are common predisposing factors for stress fracturesCommon causes in sport that result in stress fractures include
Over training
Going back to competition too soon after an injury or illness
Going from one event to another without proper training for the second event
Starting initial training too quickly
Changing habits or the environment like training surface or shoes

Diagnosis
X-rays usually do not show evidence of new stress fractures, but can be used approximately three weeks after onset of pain when the bone begins to remodel. A CT scan, MRI, or 3-phase bone scan may be more effective for early diagnosis.MRI appears to be the most accurate diagnostic test.Tuning forks have been advocated as an inexpensive alternative for identifying the presence of stress fractures. The clinician places a vibrating tuning fork along the shaft of the suspected bone. If a stress fracture is present, the vibration would cause pain. This test has a low positive likelihood ratio and a high negative likelihood ratio meaning it should not be used as the only diagnostic method. Prevention
Altering the biomechanics of training and training schedules may reduce the prevalence of stress fractures.
Most of the stress fractures observed along the lengths of Allosaurus toe bones were confined to the ends closest to the hind foot, but were spread across all three major digits in "statistically indistinguishable" numbers. Since the lower end of the third metatarsal would have contacted the ground first while a theropod was running it would have borne the most stress and should be most predisposed to develop stress fractures. The lack of such a bias in the examined fossils indicates an origin for the stress fractures from a source other than running. The authors conclude that these fractures occurred during interaction with prey. They suggest that such injuries could occur as a result of the theropod trying to hold struggling prey with its feet. The presence of stress fractures provide evidence for very active predation-based feeding rather than scavenging diets. References


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