Magnetic resonance imaging showed no signs of overuse or permanent injury to the lumbar sacral spine during a Special Forces training course.

Background Context: Special Forces training is even more demanding than that of elite athletes. The training includes grueling physical activity and periods of sleep deprivation. The soldiers routinely carry heavy loads up to 40% of their body weight on their backs while running and marching for distances up to 90 km.

Purpose: Our purpose was to find out if Special Forces recruits are able to complete the preparatory Navy Seals training program without sustaining magnetic resonance imaging (MRI) signs of overuse or irreversible injury to their backs.

Study Design/setting: Prospective cohort study. We performed MRI scans before and after 14 weeks of Navy Seals preparatory training course.

Patient Sample: Ten soldiers underwent MRI of their lumbar sacral spines and right knees before and after the completion of Navy Seals preparatory training.

Outcome Measures: Physiologic measures. Lumbar sacral spine and knee MRI tests were performed before and after the training to identify changes in the spinal discs, facet joints, pars interarticularis, vertebral bodies, knee articular cartilage, ligaments, knee menisci, and the presence or absence of soft tissue and/or bone edema.

Methods: We investigated the difference in spine and knee pathology before and after a 14-week Navy Seals preparatory training course by using MRI criteria. The recruits participating in the study were monitored for acute and overuse injuries every 3 to 4 weeks.

Results: Before the training, seven out of ten spine MRI scans were normal. Two showed small L5-S1 disc bulges, one of them with concomitant Scheuermann's disease. Another soldier's MRI showed L1-L4 mild Scheuermann's disease. Follow-up MRI showed no spinal changes. Before the training, one knee had a small lateral femoral condyle cartilage lesion. Nine of ten knees had prepatellar swelling, five had increased joint fluid, and two bone edema. Follow-up magnetic resonance imaging showed improvement in the prepatellar swelling in eight soldiers, no change in one soldier, and increased knee effusion and a new medial femoral condyle bone edema in another. The lateral femoral condyle lesion remained unchanged.

Conclusions: According to MRI criteria, the soldiers in this study completed the 14-week training, which involved loading of their spines far beyond the levels recommended by the US National Institute for Occupational Safety and Health without sustaining irreversible damage to their spines or knees. Although the subjects' knees showed signs of overuse injury, their backs did not.