Not all brawn, but some brain. Strength gains after training alters kinematic motor abundance in hopping

Liew, Bernard and Morrison, Andrew and Hobara, Hiroaki and Morris, Susan and Netto, Kevin (2018) Not all brawn, but some brain. Strength gains after training alters kinematic motor abundance in hopping. PeerJ, 6. e6010. ISSN 2167-8359

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Official URL: https://doi.org/10.7717/peerj.6010

Abstract

Background. The effects of resistance training on a muscle’s neural, architectural, and mechanical properties are well established. However, whether resistance training can positively change the coordination of multiple motor elements in the control of a well-defined lower limb motor performance objective remains unclear. Such knowledge is critical given that resistance training is an essential and ubiquitous component in gait rehabilitation. This study aimed to investigate if strength gains of the ankle and knee extensors after resistance training increases kinematic motor abundance in hopping. Methods. The data presented in this study represents the pooled group results of a sub-study from a larger project investigating the effects of resistance training on load carriage running energetics. 30 healthy adults performed self-paced unilateral hopping, and strength testing before and after six weeks of lower limb resistance training. Motion capture was used to derive the elemental variables of planar segment angles of the foot, shank, thigh, and pelvis, and the performance variable of leg length. Uncontrolled manifold analysis (UCM) was used to provide an index of motor abundance (IMA) in the synergistic coordination of segment angles in the stabilization of leg length. Bayesian Functional Data Analysis was used for statistical inference, with a non-zero crossing of the 95% Credible Interval (CrI) used as a test of significance. Results. Depending on the phase hop stance, there were significant main effects of ankle and knee strength on IMA, and a significant ankle by knee interaction effect. For example at 10 % hop stance, a 1 Nm/kg increase in ankle extensor strength increased IMA by 0.37 (95% CrI 0.14 to 0.59), a 1 Nm/kg increase in knee extensor strength decreased IMA by 0.29 (95% CrI 0.08 to 0.51), but increased the effect of ankle strength on IMA by 0.71 (95% CrI 0.10 to 1.33). At 55% hop stance, a 1 Nm/kg increase in knee extensor strength increase IMA by 0.24 (95% CrI 0.001 to 0.48), but reduced the effect of ankle strength on IMA by 0.71 (95% CrI 0.13 to 1.32). Discussion. Resistance training not only improves strength, but also the structure of coordination in the control of a well-defined motor objective. The role of resistance training on motor abundance in gait should be investigated in patient cohorts, other gait patterns, and its translation into functional improvements.

Item Type: Journal Article
Keywords: Resistance training, Spring-mass model, Uncontrolled manifold, Synergy
Faculty: Faculty of Science & Technology
Depositing User: Andrew Morrison
Date Deposited: 29 Oct 2018 14:49
Last Modified: 27 Nov 2018 12:35
URI: http://arro.anglia.ac.uk/id/eprint/703768

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