Barefoot Running and Hip Kinematics: Good News for the Knee?

Purpose: Patellofemoral pain and iliotibial band syndromes are common running injuries. Excessive hip adduction (HADD), hip internal rotation (HIR), and contralateral pelvic drop (CLPD) during running have been suggested as causes of injury in female runners. This study compared these kinematic variables during barefoot and shod running. Methods: Three-dimensional gait analyses of 23 habitually shod, uninjured female recreational athletes running at 3.33 m.s(-1) while shod and barefoot were studied. Spatiotemporal and kinematic data at initial contact (IC), 10% of stance (corresponding to the vertical impact peak), and peak angles were collected from each participant for HADD, HIR, and CLPD, and differences were compared across footwear conditions. Results: Step rates when running barefoot were 178 +/- 13 versus 172 +/- 11 steps per minute when shod (P < 0.001). Foot-strike patterns changed from a group mean heel-toe latency indicating a rear-foot strike (20.8 ms) when shod, to one indicating a forefoot strike (-1.1 ms) when barefoot (P < 0.001). HADD was lower at IC and at 10% of stance when running barefoot (2.3 degrees +/- 3.6 degrees vs 3.9 degrees +/- 4.0 degrees, P < 0.001 and 2.8 degrees +/- 3.5 degrees vs 3.8 degrees +/- 3.7 degrees, P < 0.01), as was HIR (7.9 degrees +/- 6.1 degrees vs 10.8 degrees +/- 6.1 degrees, P < 0.001 and 4.1 degrees +/- 6.3 degrees vs 7.0 degrees +/- 5.8 degrees, P < 0.01) and CLPD (0.4 degrees +/- 2.4 degrees vs -0.4 degrees +/- 2.3 degrees, P < 0.01 and 0.8 degrees +/- 2.7 degrees vs 0.3 degrees +/- 2.5 degrees, P < 0.05). There were no significant differences detected in peak data for hip kinematics. Conclusions: Barefoot running resulted in lower HADD, HIR, and CLPD when compared to being shod at both IC and 10% of stance, where the body's kinetic energy is absorbed by the lower limb. Because excessive HADD, HIR, and CLPD have been associated with knee injuries in female runners, barefoot running could have potential for injury prevention or treatment in this cohort.