The Effect of Foot Strike Pattern on Achilles Tendon Load During Running

Abstract

In this study we compared Achilles tendon loading parameters during barefoot running among females with different foot strike patterns using open-source computer muscle modeling software to provide dynamic simulations of running. Muscle forces of the gastrocnemius and soleus were estimated from experimental data collected in a motion capture laboratory during barefoot running for 11 runners utilizing a rearfoot strike (RFS) and 8 runners utilizing a non-RFS (NRFS) pattern. Our results show that peak Achilles tendon force occurred earlier in stance phase (p = 0.007), which contributed to a 15% increase in average Achilles tendon loading rate among participants adopting a NRFS pattern (p = 0.06). Stance time, step length, and the estimated number of steps per mile were similar between groups. However, runners with a NRFS pattern experienced 11% greater Achilles tendon impulse each step (p = 0.05) and nearly significantly greater Achilles tendon impulse per mile run (p = 0.06). This difference equates to an additional 47.7 body weights for each mile run with a NRFS pattern. Runners considering a NRFS pattern may want to account for these novel stressors and adapt training programs accordingly.

Manipulation of Foot Strike and Footwear Increases Achilles Tendon Loading During Running

“…Kulmala et al 17 ) and therefore increased GRF. Almonroeder et al 1 explained that their approach, where ankle dorsiflexion muscle activity was not assumed to be zero, resulted in greater force estimates than when using inverse dynamics (as in the present study). It is well established that there are greater internal plantar flexor moments when running with a FFS compared with a RFS 17,25,27 , and this was also the case in the present study, where the plantar flexor moments were 4% greater when running with a FFS compared with a RFS.…”

“…Three previous studies have investigated the influence of running with different foot strike patterns on Achilles tendon loading, with conflicting findings 1,17,25 . These findings may have been influenced by the footwear worn during the assessment of Achilles tendon loading.…”

“…Almonroeder 1 suggest that Achilles tendon injury may result from submaximal, repetitive loading or from repeated high rates of loading.…”

“…These differences in mechanics likely influence the Achilles tendon force, the rate of loading, and therefore potentially the risk of Achilles tendon injury 1 . Existing literature assessing the influence of footwear on Achilles tendon loading 7,8,25,31 and Achilles tendon strain (indicated by ankle dorsiflexion) 7,25 is similarly confounded by the effects of foot strike.…”

Investigation into the kinetics and kinematics during running in the heelless shoe

“…To estimate Achilles tendon kinetics the plantarflexion moment calculated was divided by an estimated Achilles tendon moment arm of 0.05 m (Komi et al 1990, Scott andWinter 1990). From the Achilles tendon force measures of peak force, time to peak force, average loading rate and instantaneous loading rate were obtained in accordance with Almonroeder et al (2013). From the GRF data, four parameters including average vertical loading rate, instantaneous vertical loading rate, peak vertical impact force and time to peak impact were calculated and subsequently included in statistical analy-sis (Sinclair et al 2013a).…”