Gait retraining to reduce lower extremity loading in runners

Abstract

Background: tibial stress fractures, which are among the most common running related injuries, have been associated with increased lower extremity loading (i.e., peak positive acceleration of the tibia, vertical force impact peak, and average and instantaneous vertical force loading rates) during initial contact. This study was conducted to evaluate the efficacy of a gait retraining program designed to reduce this loading during running and to assess the short-term persistence of these reductions.

Methods: ten runners (six females and four males) with peak positive tibial acceleration greater than 8g, measured in an initial screening, participated in the retraining program. During the retraining sessions, subjects ran on a treadmill and received real-time visual feedback from an accelerometer attached to their distal tibias. Tibial acceleration and vertical ground reaction force data were collected from subjects during overground data collection sessions held pre-training, post-training, and at a 1-month follow-up.

Findings: peak positive acceleration of the tibia, vertical force impact peak, and average and instantaneous vertical force loading rates were all reduced immediately following the gait retraining. The decrease in tibial acceleration was nearly 50%. The reductions in vertical force loading rates and vertical force impact peak were approximately 30% and 20%, respectively. These reductions were maintained at the 1-month follow-up.

Interpretation: subjects were able to run with reduced tibial acceleration and vertical force loading immediately following completion of the gait retraining program and at the 1-month follow-up evaluation. This may reduce their risk of stress fractures.

Fig. 1

Accelerometer taped to the anteromedial aspect of the subject’s distal tibia.

Fig. 2

Variables of interest: PPA obtained from (a) the tibial acceleration curve and VIP, VILR, and VALR obtained from (b) the vertical ground reaction force curve. Note that both vertical loading rates (VILR and VALR) were calculated in the region between 20% and 80% of the VIP.

Fig. 3

Example of the real-time feedback from the accelerometer that was presented to subjects while they ran on the treadmill. Subjects were instructed to maintain their tibial acceleration below the horizontal line set at 50% of their peak values.

Fig. 4

Schedule of running time and feedback time over the 8 retraining sessions. Note that the feedback was gradually removed after the fourth session.

Fig. 5

Mean (SD) (a) peak positive tibial acceleration (PPA) and (b) vertical impact peak (VIP) at pre-training, post-training, and 1-month follow-up. * Indicates significantly different from pre-training, P≤0.05.

Fig. 6

Mean (SD) vertical instantaneous loading rate (VILR) and vertical average loading rate (VALR) at pre-training, post-training, and 1-month follow-up. * Indicate significantly different from pre-training, P<0.05.