Adaptations in trunk-pelvis coordination variability in response to fatiguing exercise.
BACKGROUND
During walking, variability in how movement is coordinated between body segments from stride to stride facilitates adaptation to changing environmental or task constraints. Magnitude of this inter-segmental coordination variability is reduced in patient populations and may also decrease in response to muscle fatigue. Previously, stride-to-stride variability has been quantified with the Vector Coding (VC) method, however recent research introduced a new Ellipse Area Method (EAM) to avoid statistical artifacts associated with VC.


RESEARCH QUESTION
Determine changes in trunk-pelvis coordination variability during walking turns in response to fatiguing exercise and to compare coordination variability quantified with VC to the EAM method.


METHODS
15 young adults (mean age: 23.7 (±3.2) years) performed 15 trials of a 90-degree walking turn before and after fatiguing paraspinal muscle exercise. Angular kinematics of the trunk and pelvis segments in the axial plane were quantified using three-dimensional motion capture. Stride to stride variability of axial coordination between the trunk and pelvis pre- and post-fatigue was calculated using both VC and EAM methods. Magnitudes of pre- and post-fatigue variability for VC and EAM were compared with paired t-tests and relationship between the magnitude of variability for the two methods was calculated using Pearson correlation coefficients.


RESULTS
Using both analytical approaches, trunk-pelvis coordination variability decreased significantly post-fatiguing exercise across the stride cycle and within the stance phase of the turn (p < 0.034 for all comparisons). Average magnitudes of variability calculated with VC and EAM were highly correlated. Time series cross correlations pre-post fatigue ranged from 0.81 to 0.98.


SIGNIFICANCE
In healthy individuals, magnitude of trunk-pelvis stride-to-stride coordination variability is reduced following fatiguing exercise but the temporal distribution of variability across the stride cycle is maintained. This finding is robust to the method used to quantify coordination variability.
['Smith|Jo Armour|JA|', 'Eiteman-Pang|Wilford K|WK|', 'Soangra|Rahul|R|', 'König Ignasiak|Niklas|N|']
D000222:Adaptation, Physiological D000328:Adult D001696:Biomechanical Phenomena D015444:Exercise D005221:Fatigue D005260:Female D064368:Healthy Volunteers D006801:Humans D008297:Male D010388:Pelvis D060726:Torso D055815:Young Adult
Coordination variability Muscle fatigue Paraspinal muscles Gait