M.Sc. Luca Braun (Offenburg), M.Sc. Markus Hipper (Offenburg), M.Sc. Yannick Denis (Offenburg), M.Sc. Janina Helwig (Offenburg), M.Sc. Bastian Anedda (Offenburg), Prof. Dr. Steffen Willwacher (Offenburg)
Abstract-Text (inkl. Referenzen und Bildunterschriften)
Introduction Altering anterior trunk leaning (ATL) may be a particularly interesting variable to redistribute lower extremity joint loading because the trunk has the largest segmental mass. There is some evidence that running with ATL reduces cumulative knee joint loading (cKJL), but a potential trade-off with running economy (RE) is currently uncertain.
Objectives Establishing dose-response relationships by investigating the effects of a systematic modification of ATL on cKJL and RE in running.
Methods Twenty-nine recreational runners underwent a series of six treadmill runs (2.5 m/s) with five predefined (from -4° extension to 28° flexion) and one self-selected ATL condition for five minutes each. Motion capturing was used to determine joint biomechanics. cKJL was calculated by multiplying the time integral of the dominant direction of the joint moment curve by the number of strides required to complete a 1000-m distance. 3D marker data were live-streamed using a custom-made model to provide real-time feedback on ATL angle to the participants. RE was quantified using spirometry.
Results The modification in ATL systematically altered cKJL (p <.001, rmANOVA) in all conditions. Linear regression revealed that each degree of ATL reduced cKJL by 1.06 Nm·s/kg/1000 m (Fig.1A). However, the results of RE indicate that running outside the preferred running style increases oxygen uptake. ATL28° is characterized by a reduction of 11.01% (pbonferroni < .001) in RE compared to the self-selected ATL condition (Fig.1B).
Summary Increasing ATL leads to a linear decrease in cKJL. Deviating from self-selected ATL worsens RE. Designing load-management interventions based on ATL seems promising because of the potential real-world quantification with IMUs. However, when implementing this intervention in clinical practice the trade-off between cKJL and RE must be considered.
Fig 1. cKJL was negative, but is presented in absolute terms. The grey dot is the self-selected condition.