Influence Of Running Velocity, Incline And Percentage Of Body Weight Reduction On Plantar Loading

Lower extremity injuries are common among runners, often due to high plantar loading. Anti-gravity treadmills, which offload a percentage of the user’s body weight, are frequently used in rehabilitation. While prior studies have examined running velocity, incline, or a reduction body weight on plantar loading, the combined influences of these factors on plantar loading and contact area remains unclear. Purpose: This study investigates how variations in running velocity, incline, and a reduction in body weight affect plantar loading variables. METHODS: Thirteen healthy heel strike runners (7 males, 6 females; age: 21 ± 2.5 years, mass: 68.26 ± 12.33 kg, height: 174.20 ± 14.37 cm), ran under randomized conditions at 3 velocities (2.2, 3.1, and 4.0 m/s), inclines (0%, 10%), and body weight reduction (20%, 50%, 100%) for one minute, with two-minute rest intervals. The antigravity treadmill used an enclosed air pressure-based system to provide the loading reduction. In-shoe plantar loading of the dominant leg was measured using a pressure distribution system at 200 Hz. Initial contact for each step was identified by vertical ground reaction force (VGRF) above 20 N. Repeated measure univariate analysis of variance with Bonferroni post hoc correction (α = .05) was applied to compare peak VGRF, peak pressure, and contact area across 18 conditions. RESULTS: Peak VGRF (p < .001), peak pressure (p = .031) and contact area (p = .017), were different across conditions. Body weight reductions lowered peak VGRF, although this trend was inconsistent for plantar pressure and contact area at 20% body weight. Running velocity influenced all variables, with increases leading to higher peak VGRF and pressure but lower contact area. The increased incline elevated VGRF and contact area in majority of conditions, but the effect on plantar pressure varied when more of the runner’s body weight was reduced. Interaction effects between conditions were not statistically significant. CONCLUSION: Increased running velocity and incline increase plantar loading variables at full body weight. However, running with a reduction of 20% body weight alters running mechanics, making plantar pressure and contact area less systematic This suggests that use of higher body weight reductions appears to alter the typical running patterns in heel strike runners. Supported by: The authors wish to thank the WiscAMP Summer Research Program for their support of this project