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
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).
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.
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.
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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