Cadence and tibial acceleration in runners with and without patellofemoral pain

BACKGROUND: Patellofemoral pain (PFP) is one of the main injuries in runners and the most common site of injury during ultramarathon races. The association between running biomechanics and PFP has been investigated over the years and conflicting to moderate evidence were found for kinematic and kinetic aspects. Differences in cadence and tibial acceleration should be investigated, as they are accessible variables used in gait retraining. OBJECTIVE: To compare the cadence and peak vertical tibial acceleration between runners with PFP and pain-free controls. METHODS: Cross-sectional study with 53 recreational rearfoot strike runners (PFP n = 27; Controls n = 26). All participants ran at 10 km/h on a motorized treadmill (Movement XL 1600) for 1 minute with the Tgforce accelerometer (v2.0.0.10) fixed to the anteromedial region of the right tibia above the medial malleolus. Cadence (steps/min) and vertical acceleration of the tibia (g) were measured. A significance level of α = 0.05 was adopted. RESULTS: Values of 164.22 (8.08) steps/min and 6.88 (2.01) g were found for participants with PFP, whereas 171.53 (9.89) steps/min and 6.62 (1.55) g were found for the pain-free controls. A significant difference was found for cadence (p = .007; d = 0.80) but not for vertical tibial acceleration (p > .05; d = 0.21). CONCLUSION: Participants with PFP had lower cadence values when compared to healthy runners. However, differences in tibial vertical acceleration were not found. Future studies should evaluate other aspects that can discriminate between healthy runners and those with PFP.