B-16 Free Communication/Slide - Sports Biomechanics I: MAY 27, 2009 1:00 PM - 3:00 PM ROOM: 2AB
High vertical loading, such as peak positive tibial acceleration (PPA) and vertical loadrate (VLR), have been associated with tibial stress fractures in runners. In addition, high free moments (torsional loading between the foot and the ground) have also been implicated. We have shown that runners are able to reduce their PPA and VLR through a gait retraining protocol using real-time feedback. However, it is unknown whether torsional loading is reduced as well.
PURPOSE: To determine whether reductions in vertical loading following gait retraining are also associated with decreases in torsional loading.
METHODS: Data from 8 subjects (23±7 yrs) have been collected, to date. Subjects ran >10 mpw. All subjects exhibited baseline PPA >8g's, placing them at increased risk for stress fractures. They each completed 8 sessions of real-time visual feedback training aimed at teaching them to land softer and decrease their vertical loading. We measured PPA, VLR, the adduction free moment (resisting toe out) (FMADD), and the free moment at peak braking force (FMBR) pre and post retraining. The data are presented descriptively due to low subject numbers at this time.
RESULTS: All subjects reduced their PPA and VLR by 41 and 28%, respectively. On average, FMADD decreased 3% while FMBR increased 20% (Table 1). However, 5/8 subjects did demonstrate a reduction in their torsional loading with an average decrease of 13.7% for FMADD and 19.2% for FMBR. Subjects who did not have an associated reduction in their torsional loading may have adopted a different gait strategy than the others.
CONCLUSION: Torsional loading is reduced in most subjects as a result of a gait retraining program aimed at reducing vertical loads.