DOI: 10.5061/dryad.1c59zw3sk
title: Sagittal plane lower body angles during overground running with wearable resistance

description: Field-based sports require athletes to run submaximally over significant
 distances, often while contending with dynamic perturbations to preferred
 coordination patterns. The ability to adapt movement such that performance
 is maintained under such perturbations appears to be trainable. This may
 be achieved through exposure to task variability, provided there is
 concomitant exploration of alternate functional states through movement
 variability. Wearable resistance is a novel training device, which may be
 well suited to inducing movement variability during running given the
 changes to limb inertial properties. To investigate this, 14 participants
 performed 10 submaximal speed shuttle runs with either no weight, 1%, 3%,
 or 5% of body weight attached to the lower limbs. Sagittal plane lower
 limb joint kinematics from one complete stride cycle in each run were
 assessed using functional data analysis techniques. At the group-level,
 decreases in ankle plantarflexion following toe-off were evident in the 3%
 and 5% conditions, while increased knee flexion occurred during weight
 acceptance in the 5% condition. Individual-level between-run joint angle
 profiles varied, with several participants exhibiting increased joint
 angle variability in one or more loading conditions compared with unloaded
 running. Practically, 5% loading appears to constrain the movement system
 among certain individuals in accordance with the need to manage increased
 system load or the novelty of the task. For individuals in which
 between-run joint angle variability increased under loading, wearable
 resistance seemingly promoted exploration of different coordinative modes,
 though the magnitude of loading that elicited this response varied.
 Practitioners should prescribe wearable resistance individually to ensure
 that movement variability is encouraged without substantial alteration to
 or constraint of athletes’ coordinative structures.
description: <b>Data collection
 apparatus</b> A 10-camera VICON motion analysis
 system (T-40 series, Vicon Nexus v2, Oxford, UK) sampling at 250 Hz was
 used for collection of kinematic data. A total of thirty-six reflective
 markers with 14mm diameter were attached to lower body landmarks on the
 pelvis, thighs, shanks, and feet according to the Plug-In-Gait model
 (Plug-In-Gait Marker Set, Vicon Peak, Oxford, UK). <b>Wearable
 resistance</b> Throughout testing, participants
 wore Lila<sup>TM </sup>Exogen<sup>TM</sup>
 (Sportboleh Sdh Bhd, Kuala Lumpur, Malaysia) compression shorts and calf
 sleeves. During WR exposure trials, a combination of 50, 100, and 200g
 loads totalling the required proportion of participants’ body weights were
 attached to the compression garments. Loads were distributed in a 2:1
 thigh:shank ratio, with even distribution on anterior and posterior
 surfaces. <b>Experimental
 setup</b> Testing was undertaken on a 20 m
 section of the Biomechanics Laboratory at Victoria University. Motion
 analysis cameras were arranged around the 10 m mark of the 20 m section
 and the approximate capture volume was 6.0 m long, 2.5 m high, and 3.0 m,
 wide. <b>Data
 collection</b> Following application of
 compression garments and attachment of reflective markers, participants
 undertook an initial warm-up in which they ran back and forth along the 20
 m section in a “shuttle” fashion for 2 min. Running speed was dictated
 through the use of an audible metronome, which counted each second from
 1-9, before repeating for every subsequent shuttle. Participants underwent
 a 2 min rest period following the first warm-up run before performing a
 second warm-up run for 1 min at an increased speed defined by 6 s shuttle
 efforts. Owing to the requirement of 180<sup>o</sup> changes
 of direction after each shuttle, running speeds achieved through the
 capture area were greater than the theoretical straight-line speed of 3.3
 m.s<sup>-1</sup>. Analysis of pilot data showed mean ± SD
 speeds of 4.16 ±  0.36 m.s<sup>-1</sup> through the capture
 area. Such speeds are commonly described as “striding” or “running” in
 field based sports, but fall below the “high-intensity” classification,
 often defined as &gt;5.4 m.s<sup>-1</sup>. The first trial was performed
 with body weight only (BW), and participants completed 2 min worth of 20 m
 shuttles with the 6 s pacing speed per shuttle. Captures were taken each
 time participants passed through the 10 m mark capture area during runs
 from the start point to the 20 m mark only. Captures were not performed on
 the return shuttles. This process yielded capture of 10 complete strides
 across the 2 min trial. Participants performed three
 subsequent 2 min running trials in which they were allocated WR loading of
 1%, 3%, and 5% of body weight in a randomised order. Each trial was
 interspersed with a 3 min rest period. The result of this protocol was 10
 complete overground running strides per condition, per participant, for
 analysis. <b>Data
 processing</b> Visual 3D software (C-motion,
 Rockville, MD, USA) was used to construct a seven segment model (pelvis,
 thighs, shanks, and feet) for each participant. Files in which several
 marker trajectories were lost and accurate model construction could not be
 performed were excluded from analysis. Out of a possible 560 files
 per-joint, 510 were successfully reconstructed for the hip, 530 for the
 knee, and 521 for the ankle. For a record of excluded files and the
 participants and runs to which these pertained, see S1 Table. For
 successfully reconstructed files, marker trajectories were smoothed via a
 fourth order low-pass Butterworth filter with 10 Hz cut-off frequency,
 based on mean residual amplitudes. Each file was trimmed to one complete
 stride cycle, which was defined as the period between two consecutive
 toe-off events on the same limb. Toe-off events were identified from the
 position profile of the toe marker in the z-axis. Time-continuous sagittal
 plane joint angles for the hip, knee, and ankle (<sup>o</sup>)
 were normalised to 100% of the stride cycle for further analysis. Positive
 and negative joint angles were defined relative to the positions of joints
 in upright standing. Positive joint angles indicate positions of hip
 flexion, knee flexion, and ankle dorsiflexion relative to standing, while
 negative joint angles indicate positions of hip extension, knee extension,
 and ankle plantarflexion relative to standing.
description: Missing data values are denoted by NA values.