Patellofemoral pain (PFP) is a common injury in runners that is often caused by aberrant frontal-plane hip and/or pelvis kinematics. Gait training has been proven to be helpful, but it often can only occur in a clinical or laboratory setting.
A new study, “A 10% Increase in Step Rate Improves Running Kinematics and Clinical Outcomes in Runners With Patellofemoral Pain at 4 Weeks and 3 Months,” however suggests that a simple change in step rate may be all that is needed to improve clinical outcomes. The study was recently published in the American Journal of Sports Medicine.
Running Kinematics
According to previous research, incidence rates of patellofemoral pain have been as high as 20.8% while prevalence rates as high as 22.7%. Common characteristics of runners with PFP include increased hip adduction (HADD), hip internal rotation and contralateral pelvic drop (CPD). One theory is that the aberrant frontal- and transverse-plane running kinematics causes lateral tracking of the patella which puts more stress on the patellofemoral joint.
The researchers explained in their study, “When exposed to repeat loading cycles during running, the knee may experience damage to the underlying chondral surface, stress within the subchondral bone, and excitation of nociceptors, leading to pain and injury.”
Studies have shown improvements in the rehabilitation of PFP with mirror retraining, real-time feedback and transitioning to a forefoot contact.
However, because mirror retraining and real-time feedback can only occur in clinical and laboratory settings and transitioning to a forefoot strike can increase Achilles tendon and ankle joint loading, there is need for a more practical option like a change in step rate which can be done more independently.
Only three studies so far have looked at the effects of increasing the step rate among runners with PFP. One study did find improved frontal-plane hip and pelvis kinematics and a reduction in pain, but it did not include a long follow-up. Another study did not find it any more effective than education on load management while a third study found only small improvements after two weeks of retraining.
Chris Bramah, MCSP, Msc, with the School of Health Sciences at the University of Salford in the United Kingdom talked to OTW about why gait retraining is so effective for patellofemoral pain. He said:
“I think one reason for its effectiveness is that it can target biomechanical parameters that may be contributing to PFP. Certain kinematic patterns have been prospectively linked to PFP (increased hip adduction for example), it is generally thought that kinematics such as hip adduction and contralateral pelvic drop, may affect the arthrokinematics at the patellofemoral joint leading to elevated patellofemoral joint stress.”
“Therefore, gait retraining could reduce this joint stress by correcting the underlying mechanical contributors to this injury. This is what we hypothesize as a potential explanation for such positive clinical outcomes in our paper.”
He added, “However, it is important for us as clinicians to remember patellofemoral pain can often be due to multiple different factors and therefore targeting the appropriate injury or pain driver is necessary to improve clinical outcomes. In those who biomechanics may be the cause, gait retraining seems to work really well. However, this may not be the case for those where biomechanics are not the underlying driver.”
