STUDY DESIGN: Single-subject with repeated measures. OBJECTIVES: To determine if runners can use real-time visual feedback from an accelerometer to achieve immediate reductions in tibial acceleration and vertical-force loading rates. BACKGROUND: Stress fractures are a common injury among runners. Previous studies suggest that runners with higher than normal tibial acceleration and vertical-force loading rates are at increased risk for tibial stress fractures. If these runners can be trained to reduce the loading on their lower extremities, it may reduce their risk of stress fractures. METHODS: Five subjects participated in this study. All subjects ran on a treadmill, instrumented with force transducers, during a single 30-minute session that was divided into warm-up, feedback, no-feedback, and cool-down periods. During running, the subjects also wore an accelerometer taped to their distal right tibia. Peak positive acceleration of the tibia, vertical force impact peak, and average and instantaneous vertical-force loading rates were assessed at the end of the warm-up, feedback, and no-feedback periods. RESULTS: Single-subject analysis revealed that 4 of the 5 subjects had significant reductions in their peak positive acceleration at the end of the no-feedback period compared to the warm-up. In addition, all of the subjects had significant decreases in impact peak and vertical ground reaction force loading rates at the end of the no-feedback period. CONCLUSION: In a single session of training with real-time visual feedback, it appears that most runners can reduce the types of lower extremity loading associated with stress fractures. This may lead to training programs that reduce the risk of stress fractures for runners. LEVEL OF EVIDENCE: Prevention, level 5.

J Orthop Sports Phys Ther 2010;40(4):206-213, Epub 12 March 2010. doi:10.2519/jospt.2010.3166

KEY WORDS: accelerometer, gait retraining, ground reaction forces, stress fracture, tibia

STUDY DESIGN: Cross-sectional controlled laboratory study. OBJECTIVES: To investigate the kinematics of the hip, knee, and rearfoot in the frontal and transverse planes in female distance runners with a history of tibial stress fracture. BACKGROUND: Tibial stress fractures are a common overuse injury in runners, accounting for up to half of all stress fractures. Abnormal kinematics of the lower extremity may contribute to abnormal musculoskeletal load distributions, leading to an increased risk of stress fractures. METHODS: Thirty female runners with a history of tibial stress fracture were compared to 30 age-matched and weekly-running-distance–matched control subjects with no previous lower extremity bony injuries. Kinematic and kinetic data were collected using a motion capture system and a force platform, respectively, as subjects ran in the laboratory. Selected variables of interest were compared between the groups using a multivariate analysis of variance (MANOVA). RESULTS: Peak hip adduction and peak rearfoot eversion angles were greater in the stress fracture group compared to the control group. Peak knee adduction and knee internal rotation angles and all joint angles at impact peak were similar between the groups. CONCLUSION: Runners with a previous tibial stress fracture exhibited greater peak hip adduction and rearfoot eversion angles during the stance phase of running compared to healthy controls. A consequence of these mechanics may be altered load distribution within the lower extremity, predisposing individuals to stress fracture.

J Orthop Sports Phys Ther 2010;40(2):59-66. doi:10.2519/jospt.2010.3024

KEY WORDS: gait, injury, knee, lower leg, overuse, running