Biomechanics associated with bone stress injuries while using advanced footwear technology in elite distance runners.

BACKGROUND

Advanced footwear technology (AFT) is commonly used by runners during training and competition. Prior work has characterized improvements in running economy and performance. No prior work has explored whether running with AFT changes biomechanics associated with bone stress injury (BSI).

OBJECTIVE

To measure biomechanics while running in an AFT (with a carbon fiber plate), lightweight foam (responsive foam), and neutral shoe footwear in elite distance runners.

STUDY

DESIGN

Cross-sectional cohort study.

SETTING

Academic medical multisite hospital system.

PARTICIPANTS

Healthy elite male and female distance runners.

TESTING PROTOCOL: Participants ran in three different shoes (neutral, responsive foam, and AFT) in a randomized order at three self-selected speeds: training effort, a tempo run, and a 5-km race speed.

MAIN OUTCOME MEASURES: Biomechanical variables associated with BSI were measured during each speed and shoe condition: rearfoot eversion excursion, rearfoot eversion velocity, vertical ground reaction force, ankle plantarflexion moment, vertical center of mass excursion, cadence, and duty factor. A two-factor repeated measures analysis of variance was performed by shoe type and running speed using a Bonferroni correction for main effects with p value <.05 defined as significant.

RESULTS

Twenty-three runners (11 women, 12 men; average and SD for age: 25.4 ± 2.7) participated. Ankle plantarflexion moment was higher in neutral compared to the responsive foam or AFT. Rearfoot eversion excursion was lower in the neutral shoe compared to responsive foam and AFT. Rearfoot eversion velocity was higher in the responsive foam shoe compared to neutral and AFT. Cadence was lower in AFT compared to responsive foam and neutral. No other spatiotemporal variables were significant.

CONCLUSION

Increases in several biomechanical variables associated with BSI were observed during running with AFT. The changes in biomechanics were small; however, cumulative effects to bone and the lower extremity could contribute to injury. These factors should be considered when using AFT during training and competition.