Lower Extremity Joint Work Following A Long Hilly Run In Conventional And Maximalist Shoes

Abstract

Trail running is a rapidly growing discipline which often contains uphill and downhill running segments. The varying elevation requires different muscular demands than level ground running and thus may influence how joint kinetics change following a long run. Many trail runners use highly cushioned maximalist (MAX) footwear. However, the influence of MAX footwear on joint kinetics following a long run is currently unknown. PURPOSE: To determine if there are differences in joint work following a long hilly run (LHR) in conventional (CON) and MAX footwear. METHODS: Twelve trail runners (sex: 10 M, 2 F; weekly mileage: 30.3 ± 14.9 miles) were randomly assigned to either a CON or MAX shoe and ran a 10-mile LHR which matched the elevation profile of a popular local trail run. 3D kinematics and ground reaction forces were collected during five-minute level ground running sections prior to and following the LHR. Sagittal plane positive (POS) and negative (NEG) joint work for the hip, knee, and ankle were calculated by integrating the POS and NEG portions of the joint power curves. Two-way mixed ANOVAs (shoe condition, time) were used to evaluate differences in joint work. RESULTS: There were no differences between groups in any joint work parameter before the LHR (Figure 1). Following the LHR, POS (p = 0.014) and NEG knee (p = 0.041) and NEG hip (p=0.014) work increased in the MAX group. Compare to the CON group, the MAX group also had higher NEG knee work (p = 0.009) and was trending towards higher POS knee (p = 0.072). No differences were observed in ankle work or positive hip work. CONCLUSION: Proximal redistribution of joint work following a LHR was observed, but not to the extent reported in previous studies using level runs. However, the increased knee work in MAX footwear suggests the knee is being loaded more during a LHR compared to CON footwear. This may have implications for injury risk as higher knee loads are related to common running injuries. Footwear provided by New Balance, Inc.