Changes in the Plantar Flexion Torque of the Ankle and in the Morphological Characteristics and Mechanical Properties of the Achilles Tendon after 12-Week Gait Retraining.

Weijie Fu,Songlin Xiao,Lu Li,Yang Yang,Liqin Deng,Xini Zhang

doi:10.3390/life10090159

Weijie Fu, Songlin Xiao + Show 4 more

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https://doi.org/10.3390/life10090159

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Abstract

Purpose: Although the Achilles tendon (AT) is the largest and strongest tendon, it remains one of the most vulnerable tendons among elite and recreational runners. The present study aims to explore the effects of 12-week gait retraining (GR) on the plantar flexion torque of the ankle and the morphological and mechanical properties of the AT. Methods: Thirty-four healthy male recreational runners (habitual rearfoot strikers) who never tried to run in minimal shoes were recruited, and the intervention was completed (20 in the GR group vs. 14 in the control (CON) group). The participants in the GR group were asked to run in minimal shoes (INOV-8 BARE-XF 210) provided by the investigators with forefoot strike patterns during the progressive 12-week GR. Meanwhile, the participants in the CON group were instructed to run in their own running shoes, which they were familiar with, with original foot strike patterns and intensities. The morphological properties of the AT, namely, length and cross-sectional area (CSA), were obtained by using an ultrasound device. A dynamometer was utilized simultaneously to measure and calculate the plantar flexion torque of the ankle, the rate of torque development, the peak force of the AT, and the stress and strain of the AT. Results: After 12-week GR, the following results were obtained: (1) A significant time effect in the peak ankle plantarflexion torque was observed (p = 0.005), showing a 27.5% increase in the GR group; (2) A significant group effect in the CSA was observed (p = 0.027), specifically, the increase in CSA was significantly larger in the GR group than the CON group; (3) A significant time effect in the peak AT force was observed (p = 0.005), showing a 27.5% increase in the GR group. Conclusion: The effect of 12 weeks of GR is an increase in AT CSA, plantar flexor muscle strength of the ankle, and peak AT force during a maximal voluntary isometric contraction test. These changes in AT morphology and function could be positive for tendon health and could prevent future AT injury.

Highlights

Given increased attention on public health, daily life demands for exercise, and the health of individuals, it has been reported that there were up to 45 million recreational runners in the UnitedStates alone [1]
The effect of 12 weeks of gait retraining (GR) is an increase in Achilles tendon (AT) cross-sectional area (CSA), plantar flexor muscle strength of the ankle, and peak AT
The present study aims to explore the effects of 12-week GR on the plantar flexion torque of the ankle and the morphological and mechanical properties of the AT

Summary

Introduction

Given increased attention on public health, daily life demands for exercise, and the health of individuals, it has been reported that there were up to 45 million recreational runners in the UnitedStates alone [1]. Given increased attention on public health, daily life demands for exercise, and the health of individuals, it has been reported that there were up to 45 million recreational runners in the United. Life 2020, 10, 159 injured in a given year [4]; among injuries, Achilles tendinopathy is one of the main running-related musculoskeletal injuries with a high incidence (9.1%–10.9%) [5]. Repetitive high and nonhomologous loads [8], insufficient recovery time after overloading [9], and poor ankle muscle strength and flexibility have been reported to be the risk factors of AT injuries [9]. Developing a feasible training program may help improve the mechanical properties of the AT by enhancing the load-bearing capacity, and promote running performance and prevent AT injuries

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