Footwear characteristics are related to running mechanics in runners with patellofemoral pain

Running footwear is known to influence step rate, foot inclination at foot strike, average vertical loading rate (VLR) and peak patellofemoral joint (PFJ) force. However, the association between the level of minimalism of running shoes and running mechanics, especially with regards to these relevant variables for runners with patellofemoral pain (PFP), has yet to be investigated. The objective of this study was to explore the relationship between the level of minimalism of running shoes and habitual running kinematics and kinetics in runners with PFP. Running shoes of 69 runners with PFP (46 females, 23 males, 30.7 ± 6.4 years) were evaluated using the Minimalist Index (MI). Kinematic and kinetic data were collected during running on an instrumented treadmill. Principal component and correlation analyses were performed between the MI and its subscales and step rate, foot inclination at foot strike, average VLR, peak PFJ force and peak Achilles tendon force. Higher MI scores were moderately correlated with lower foot inclination (r = −0.410, P < 0.001) and lower peak PFJ force (r = −0.412, P < 0.001). Moderate correlations also showed that lower shoe mass is indicative of greater step rate (ρ = 0.531, P < 0.001) and lower peak PFJ force (ρ = −0.481, P < 0.001). Greater shoe flexibility was moderately associated with lower foot inclination (ρ = −0.447, P < 0.001). Results suggest that greater levels of minimalism are associated with lower inclination angle and lower peak PFJ force in runners with PFP. Thus, this population may potentially benefit from changes in running mechanics associated with the use of shoes with a higher level of minimalism.