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

Abstract

Background:The Achilles tendon is the most common site of tendon overuse injury in humans. There has been a recent interest in running with a forefoot strike pattern and in minimal shoes, yet evidence is currently limited regarding the combined influence of foot strike and footwear on Achilles tendon loading.Purpose: To investigate the influence of both foot strike and footwear on Achilles tendon loading in habitual rearfoot strike runners. Study Design: Crossover study designMethods: Synchronised kinematic and force data were collected from 22 habitual rearfoot strikers (11 male), who habitually run in non-minimal running shoes, during overground running at 3.6 m.s -1 . Participants ran in three different footwear conditions (standard running shoe; minimal running shoe; barefoot) with both a rearfoot strike (RFS) and an imposed forefoot strike (FFS) in each footwear condition. Achilles tendon loading was estimated using inverse dynamics, where the Achilles tendon moment arm was determined using a regression equation.Conditions were compared using a two-way repeated measures ANOVA.Results: Achilles tendon impulse was greater when running with a FFS than a RFS in minimal shoes. Achilles tendon loading rates were higher when running either in minimal shoes or barefoot than in standard shoes, regardless of foot strike. Rice and Patel, Accepted in The American Journal of Sports Medicine, 22 Feb 2017 Conclusions:In runners who habitually rearfoot strike in standard running shoes, running in minimal shoes or barefoot increased the rate of tendon loading, and running with a forefoot strike in minimal shoes increased the magnitude of tendon loading. Transitioning to these running conditions may increase the risk of tendinopathy. What is known about this subject?It has been shown that when running with a forefoot strike compared with a rearfoot strike, the internal ankle plantar flexor moment increases, but there are conflicting findings regarding whether this results in an increase in Achilles tendon force. Some of these findings may have been confounded by footwear. What this study adds to existing knowledgeThis study considered the influence of both foot strike and footwear on Achilles tendon loading during running, as well as their interactive effect. It has added to the knowledge in this area by identifying that foot strike influences the magnitude of loading, whereas footwear influences the rate, amongst habitual rearfoot strikers who are accustomed to running in standard running footwear.

Effect of habitual foot-strike pattern on the gastrocnemius medialis muscle-tendon interaction and muscle force production during running

“…Due to the initial internal dorsiflexion moment during rearfoot striking, stretching of the SEE may be supposed to either take place later in stance phase or by actively shortening the muscle. This mechanism seems likely as forefoot strikers demonstrate higher average Achilles tendon loading rates, strain, strain rates, stress and impulses compared to rearfoot strikers (6,57,62). Besides greater stretch of the SEE, the greater internal plantar flexor moment in mid-/forefoot strikers presumably also induces increased plantar flexor muscle forces to produce the greater moment.…”

Twelve-Week Gait Retraining Reduced Patellofemoral Joint Stress during Running in Male Recreational Runners

“…For the EG, the participants were required to wear minimalist shoes when executing retraining to run at a self-selected speed with moderate intensity. Forefoot strike pattern was required; i.e., the participants should use the metatarsal ball of the forefoot to strike the ground first, in which the foot was placed below the hip during landing [26]. For the CG, the participants were also required to wear minimalist shoes and maintain their original strike pattern when training at a self-selected speed with moderate intensity.…”

Effects of medial and lateral wedged orthoses on knee and ankle joint loading in female runners

“…Finally, Achilles tendinopathies are also frequently occurring chronic musculoskeletal disorders in runners, accounting for approximately 8-15% of all injuries (Van Ginckel, et al, 2009). Although the Achilles tendon is regarded as the strongest tendon in the body, it is the most common site of tendinous injury (Rice & Patel, 2017). During running, the Achilles tendon experiences forces up to 7 BW (Almonroeder, Willson, & Kernozek 2013).…”