Foot strike pattern is debated frequently, often circling the idea of natural vs. non-natural styles. However, it is obvious running with or without shoes changes biomechancis and likely increases and decreases joint stress on various structures. Understanding the changes in biomechanics when running with or without shoes is essential, as overuse injuries are very common in running.
Patellofemoral pain is one of the most common overuse injuries in swimming. Patellofemoral pain occurs when joint stress increases in the knee causing pain around the knee cap. Knee stress is altered by patellofemoral joint reaction force and patellofemoral contact area. Patellofemoral joint stress changes with varying knee, hip, and foot positions.

Ways to Reduce Patellofemoral Knee Stress While Running

Decrease Stride Length

Willson et al. showed that a reduction in step length of at least 10% resulted in an average decrease of 16.3% in PF joint stress.

Increased Step Rate

Even small increases in step rate have been shown to reduce energy absorption at the knee. A more recent investigation found that a 10% increase from preferred step rate resulted in a 14% decrease in PF joint reaction force (Lenhart 2014). Patellofemoral loading rate and impulse were also reduced by 11% and 20%, respectively, with increased step rate (Lenhart 2014).

Forefoot Strike

Roos et al.reported that knee extensor moment predicted 93% of the variance in PF joint reaction forces during forward and backward running. They also stated that a center of pressure closer to the heel was a primary predictor of increased knee extensor moments.

More anterior foot strike patterns, or less foot inclination at initial contact, have been reported to reduce overall loading of the lower extremity during running as well as decrease the stress on the knee joint (Lieberman 2010; Paquette 2013). Cheung and Davis (2011) reported in a case series that there was an improvement in symptoms in three runners with PFP when using a landing pattern modification program. They attributed these improved symptoms to decreased ground reaction forces measured after training

Peak PF joint stress decreased by 27% and the PF joint stress time-integral decreased by 12% when changing from rearfoot strike to forefoot strike.  The FFS condition resulted in a 6.6% increase in peak vertical ground reaction force and 27% decrease peak quadriceps force.

Conclusion

In conclusion, altering one’s foot strike pattern from that of a rearfoot strike to a forefoot strike with only simple instruction results in consistent reductions in PF joint stress independent of changes in step length. Thus, using programs that promote the use of a forefoot strike running pattern may be warranted in the treatment of PFP.

Keep in mind the running alteration, increased Achilles tendon strain.

Reference:

Cheung RT, Davis IS. Landing pattern modification to improve patellofemoral pain inrunners: a case series. J Orthop Sports Phys Ther. 2011;41:914-19.

Lenhart RL, Thelen DG, Wille CM, Chumanov ES, Heiderscheit BC. Increasing runningstep rate reduces patellofemoral joint forces. Med Sci Sports Exerc. 2014;46(3):557-64.

Lieberman DE, Venkadesan M, Werbel WA, et al. Foot strike patterns and collisionforces in habitually barefoot versus shod runners. Nature. 2010;463:531-5

Paquette MR, Zhang S, Dahl L. Acute effects of barefoot, minimal shoes and runningshoes on lower limb mechanics in rear and forefoot strike runners. Footwear Science.2013:5(1);9-18

Wirtz AD, Willson JD, Kernozek TW, Hong DA. Patellofemoral joint stress duringrunning in females with and without patellofemoral pain. Knee. 2012;9:703-8.

Roos PE, Barton N, van Deursen RWM. Patellofemoral joint compression forces in backward and forward running. J Biomech. 2012;45:1656-60

Nathan Vannatta C, Kernozek TW. Patellofemoral Joint Stress during Running with Alterationsin Foot Strike Pattern. Med Sci Sports Exerc. 2014 Sep 8. [Epub ahead of print]Written by John Mullen, DPT, CSCS