Repetitive trunk loading leads to faster trunk movement in response to external perturbation.

Olson, Michael W; Li, Li · J Biomech · 2018

basic_science · Level V

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Abstract

The purpose of the present study was to examine trunk movement pattern responses to mechanical perturbation before and after two different repetitive trunk flexion-extension loading schemes. Spatial and temporal parameters were studied to understand the trunk recovery from an anteriorly directed perturbation. Eighteen male and female subjects (18-27 yrs) participated in active and passive trunk flexion-extension, performed seven days apart. Subjects performed 60 trunk flexion-extension repetitions in each condition. Subjects either volitionally moved their trunks (active condition) or relaxed while a dynamometer controlled the movements (passive condition). Trunk perturbations occurred before and immediately after two 30 repetition sessions. Initial responses included latency measures of trunk displacement and peak trunk velocity (V<sub>P</sub>). Temporal measures included perturbation onset to initial trunk movement (T<sub>D</sub>), movement initiation to V<sub>P</sub> (T<sub>MIPV</sub>), and perturbation onset to V<sub>P</sub> (T<sub>PPV</sub>). Recovery measures included peak recovery velocity (V<sub>PR</sub>), recovery time (T<sub>R</sub>), velocity slope (V<sub>S</sub>), and recovery slope (R<sub>S</sub>). Differences between loading sessions were present for T<sub>PPV</sub> (p < .05), T<sub>R</sub> (p < .05), and R<sub>S</sub> (p < .05). Overall, the results indicate repetitive loading leads to lower resistance to perturbation, but faster recovery from perturbation although no differences to active or passive repetitive loading was observed.

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