Effects of Traditional Sit-up Training Versus Core Stabilization Exercises on Short-Term Musculoskeletal Injuries in US Army Soldiers: A Cluster Randomized Trial

Background. The US Army has traditionally utilized bent-knee sit-ups as part of physical training and testing. It is unknown whether the short-term effects of a core stabilization exercise program without sit-up training may result in decreased musculoskeletal injury incidence and work restriction compared with traditional training. Objective. The objective of this study was to explore the short-term effects of a core stabilization exercise program (CSEP) without sit-up training and a traditional exercise program (TEP) on musculoskeletal injury incidence and work restriction. Design. The study was designed as a cluster randomized trial. Setting. The setting was a 16-week training program at Fort Sam Houston (San Antonio, Texas). Participants. The study participants were soldiers with a mean age of 22.9 years (SD = 4,7, range = 18-35) for whom complete injury data were available for analysis (n = 1,141). Intervention. Twenty companies of soldiers were cluster randomized to complete the CSEP (10 companies of 542 soldiers) or the TEP (10 companies of 599 soldiers). The CSEP included exercises targeting the transversus abdominus and multifidus musculature. The TEP comprised exercises targeting the rectus abdominus, oblique abdominal, and hip flexor musculature. Measurements. Research staff recorded all injuries resulting in the inability to complete full duty responsibilities. Differences in the percentages of musculoskeletal injuries were examined with chi-square analysis; independent sample t tests were used to examine differences in the numbers of days of work restriction. Results. Of the 1,141 soldiers for whom complete injury data were available for analysis, 511 (44.8%) experienced musculoskeletal injuries during training that resulted in work restrictions. There were no differences in the percentages of soldiers with musculoskeletal injuries. There also were no differences in the numbers of days of work restriction for musculoskeletal injuries overall or specific to the upper extremity. However, soldiers who completed the TEP and experienced a low back injury had more days of work restriction: 8.3 days (SD = 14.5) for the TEP group and 4.2 days (SD = 8.0) for the CSEP group. Limitations. A limitation of this study was the inconsistent reporting of injuries during training. However, the rates of reporting were similar between the groups. Conclusions. The incidence of musculoskeletal injuries was similar between the groups. There was marginal evidence that the CSEP resulted in fewer days of work restriction for low back injuries.