Elsevier

Journal of Biomechanics

Volume 45, Issue 9, 1 June 2012, Pages 1656-1660
Journal of Biomechanics

Patellofemoral joint compression forces in backward and forward running

https://doi.org/10.1016/j.jbiomech.2012.03.020Get rights and content
Under a Creative Commons license
open access

Abstract

Patellofemoral pain (PFP) is a common injury and increased patellofemoral joint compression forces (PFJCF) may aggravate symptoms. Backward running (BR) has been suggested for exercise with reduced PFJCF.

The aims of this study were to (1) investigate if BR had reduced peak PFJCF compared to forward running (FR) at the same speed, and (2) if PFJCF was reduced in BR, to investigate which biomechanical parameters explained this. It was hypothesized that (1) PFJCF would be lower in BR, and (2) that this would coincide with a reduced peak knee moment caused by altered ground reaction forces (GRFs).

Twenty healthy subjects ran in forward and backward directions at consistent speed. Kinematic and ground reaction force data were collected; inverse dynamic and PFJCF analyses were performed.

PFJCF were higher in FR than BR (4.5±1.5; 3.4±1.4BW; p<0.01). The majority of this difference (93.1%) was predicted by increased knee moments in FR compared to BR (157±54; 124±51 Nm; p<0.01). 54.8% of differences in knee moments could be predicted by the magnitude of the GRF (2.3±0.3; 2.4±0.2BW), knee flexion angle (44±6; 41±7) and center of pressure location on the foot (25±11; 12±6%) at time of peak knee moment. Results were not consistent in all subjects.

It was concluded that BR had reduced PFJCF compared to FR. This was caused by an increased knee moment, due to differences in magnitude and location of the GRF vector relative to the knee. BR can therefore be used to exercise with decreased PFJCF.

Abbreviations

|GRF|
magnitude of the ground reaction force
BR
backward running
COPloc
location of the ground reaction force relative to the foot
COPlocFS
position of the center of pressure relative to the foot at foot strike
dPT
patellar tendon moment arm
Fq
quadriceps tendon force
FR
forward running
GRF
ground reaction force
Mk(max)
peak knee moment
PFJCF
patellofemoral joint compression force
PFP
patellofemoral pain
RFq-Fpl
ratio of the quadriceps to patellar tendon force
TIP
telescopic inverted pendulum
αfoot
foot segment angular acceleration
αshank
shank segment angular acceleration
αthigh
thigh segment angular acceleration
θGRF
orientation of the ground reaction force relative to the ground
θK
knee flexion angle
θL
orientation of the lower limb segment in the TIP model (see Fig. 1)

Keywords

Patellofemoral pain
Running
Backward running
Rehabilitation
Patellofemoral joint compression force

Cited by (0)