Efficacy of an Audio-Based Biofeedback Intervention to Modify Running Gait in Female Runners.

Context: A variety of gait retraining interventions are available to modify running mechanics associated with musculoskeletal injuries. These often require specialized equipment and/or personnel to prompt the runner toward specific strategies.

Objective: To determine whether instructing female recreational runners to "run quietly" could decrease impact force characteristics.

Design: Cohort.

Setting: Research laboratory.

Participants: Fifteen healthy female recreational runners (24 [7] y) volunteered.

Interventions: Baseline testing occurred on day 1 (baseline), a posttraining assessment occurred on day 2 (training), and a final assessment occurred 1 week after training on day 3 (follow-up). A smartphone decibel measuring app was used to provide biofeedback on the decibel level of foot strike on day 2 (training).

Main Outcomes: Peak vertical force, impact transient, peak and average vertical loading rate, ground contact time, and running economy were collected on each day and compared via repeated-measures analyses of variance.

Results: Vertical ground reaction force was lower at follow-up (2.30 bodyweights [BW]) versus baseline (2.39 BW, P = .023) and training (2.34 BW, P = .047). Maximal loading rate decreased from baseline (69.70 BW·s-1) to training (62.24 BW·s-1, P = .021) and follow-up (60.35 BW·s-1, P = .031). There was no change in running economy.

Conclusions: Our findings demonstrate that simple instructions to "run quietly" can yield immediate and sustained reductions in impact force profiles, which do not influence running economy.