AUTHOR=Pamboris George M. , Noorkoiv Marika , Baltzopoulos Vasilios , Powell Douglas W. , Howes Tom , Mohagheghi Amir A. 

TITLE=Influence of dynamic stretching on ankle joint stiffness, vertical stiffness and running economy during treadmill running

JOURNAL=Frontiers in Physiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2022.948442

DOI=10.3389/fphys.2022.948442

ISSN=1664-042X

ABSTRACT=<p>The purpose of the present study was to investigate whether and how dynamic stretching of the plantarflexors may influence running economy. A crossover design with a minimum of 48 h between experimental (dynamic stretching) and control conditions was used. Twelve recreational runners performed a step-wise incremental protocol to the limit of tolerance on a motorised instrumented treadmill. The initial speed was 2.3 m/s, followed by increments of 0.2 m/s every 3 min. Dynamic joint stiffness, vertical stiffness and running kinematics during the initial stage of the protocol were calculated. Running economy was evaluated using online gas-analysis. For each participant, the minimum number of stages completed before peak O<sub>2</sub> uptake (V̇O<sub>2peak</sub>) common to the two testing conditions was used to calculate the gradient of a linear regression line between V̇O<sub>2</sub> (<italic>y</italic>-axis) and speed (<italic>x</italic>-axis). The number of stages, which ranged between 4 and 8, was used to construct individual subject regression equations. Non-clinical forms of magnitude-based decision method were used to assess outcomes. The dynamic stretching protocol resulted in a <italic>possible</italic> decrease in dynamic ankle joint stiffness (−10.7%; 90% confidence limits ±16.1%), a <italic>possible</italic> decrease in vertical stiffness (−2.3%, ±4.3%), a <italic>possibly beneficial</italic> effect on running economy (−4.0%, ±8.3%), and <italic>very likely</italic> decrease in gastrocnemius medialis muscle activation (−27.1%, ±39.2%). The results indicate that dynamic stretching improves running economy, <italic>possibly via</italic> decreases in dynamic joint and vertical stiffness and muscle activation. Together, these results imply that dynamic stretching should be recommended as part of the warm-up for running training in recreational athletes examined in this study.</p>