Comparison of shank, rearfoot and forefoot coordination and its variability between runners with different strike patterns

This study aims to compare shank, rearfoot and forefoot coordination and its variability between runners with habitual rearfoot strike (RFS) and non-RFS (NRFS). 58 healthy males participated in this study (32 RFS, 26 NRFS). Coordination patterns and variability were assessed for the shank, rearfoot, and forefoot segments using a modified vector coding technique during running. RFS runners exhibited significantly greater proportion of anti- phase with distal dominancy (rearfoot) during early and mid-stance, as well as a lower proportion of anti-phase with proximal dominancy (shank) during early stance compared to NRFS runners in frontal rearfoot- transverse shank (FRTS). Conversely, NRFS runners demonstrated significantly greater proportion of anti-phase with distal dominance (forefoot) in the sagittal, frontal, and transverse planes during early stance compared to RFS runners. Coordination variabilities for the FRTS (late stance), frontal rearfoot - frontal forefoot (FRFF) (early and late stance), and frontal rearfoot- transverse forefoot (FRTF) (mid stance) were greater in NRFS than in RFS runners. In contrast, coordination variability for frontal rearfoot - sagittal forefoot (FRSF) (early stance) was greater in RFS than in NRFS runners. The results could further extend the relationship between foot strike pattern and injuries from the perspective of coordination and its variability. Preliminary findings suggest that NRFS runners could benefit from intrinsic foot muscle training to mitigate the sustained loads on the soft tissues of the foot.