AUTHOR=Napier Christopher , Fridman Lauren , Blazey Paul , Tran Nicholas , Michie Tom V. , Schneeberg Amy 

TITLE=Differences in Peak Impact Accelerations Among Foot Strike Patterns in Recreational Runners

JOURNAL=Frontiers in Sports and Active Living

VOLUME=Volume 4 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/sports-and-active-living/articles/10.3389/fspor.2022.802019

DOI=10.3389/fspor.2022.802019

ISSN=2624-9367

ABSTRACT=INTRODUCTION: Running-related injuries (RRIs) occur from a combination of training load errors and aberrant biomechanics. Impact loading, measured by peak acceleration, is an important measure of running biomechanics that is related to RRI. Footstrike pattern may moderate the magnitude of impact load in runners. The effect of footstrike pattern on peak acceleration has been measured using tibia-mounted inertial measurement units (IMUs), but not commercially available insole-embedded IMUs. The aim of this study was to compare the peak acceleration signal associated with rearfoot (RFS), midfoot (MFS), and forefoot (FFS) strike patterns when measured with an insole-embedded IMU. MATERIALS AND METHODS: Healthy runners ran on a treadmill for one minute at three different speeds with their habitual footstrike pattern. An insole-embedded IMU was placed inside standardized neutral cushioned shoes to measure the peak resultant, vertical, and anteroposterior accelerations at impact. Footstrike pattern was determined by two experienced observers and evaluated using high-speed video. Linear mixed effect models were used to quantify the relationship between footstrike pattern and peak resultant, vertical, and anteroposterior acceleration. RESULTS: Eighty-one percent of the 187 participants exhibited a RFS pattern. A RFS pattern was associated with a higher peak resultant (0.29 standard deviations [SD]; p=0.029) and vertical (1.19SD; p<0.001) acceleration when compared to a FFS running pattern, when controlling for speed and limb, respectively. However, a MFS was associated with the highest peak accelerations in the resultant direction (0.91SD vs FFS; p=0.002 and 0.17SD vs RFS; p=0.091). A FFS pattern was associated with the lowest peak accelerations in both the resultant and vertical directions. A RFS was also associated with a significantly greater peak acceleration in the anteroposterior direction (0.28SD; p=0.033) than a FFS pattern, while there was no difference between MFS and FFS patterns. DISCUSSION: Our findings indicate that runners should be grouped by RFS, MFS, and FFS when comparing peak acceleration, rather than the common practice of grouping MFS and FFS together as non-RFS runners. Future studies should aim to determine the risk of RRI associated with peak accelerations from an insole-embedded IMU to understand whether the small observed differences in this study are clinically meaningful.