Validity of Velocity Measurements of a Motorized Resistance Device During Change of Direction.

Ola Eriksrud,Øyvind Gløersen,Fredrik Ahlbeck,Damian Harper

doi:10.3389/fphys.2022.824606

Ola Eriksrud, Øyvind Gløersen + Show 2 more

Open Access

https://doi.org/10.3389/fphys.2022.824606

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Abstract

The aim of this study was to determine validity of velocity measurements of a motorized resistance device (MRD) during change of direction (CoD). Eight male (age: 22.1 ± 4.2 yrs; weight: 83.3 ± 17.1 kg; height: 181.6 ± 12.6 cm) and three female participants (age: 21.7 ± 1.5 yrs; mass: 69.7 ± 2.4 kg; height: 167.0 ± 3.6 cm) completed the modified 505 CoD test (m505) with turning off the left and right foot while exposed to external loads (3, 6, and 9 kg) provided by the MRD. Three-dimensional kinematic data were measured (200 Hz) for all tests using a full-body marker set with an additional marker placed on the pulley used to attach the carabiner (CAR) at the end of the line from the MRD to the participant. Average velocity of overall center of mass (COMvel), pelvis (COMpelvis_vel), and pulley (CARvel) was then calculated and compared to the velocity measured by MRD (MRDvel) in 0.5 s intervals 1.5 s before and after CoD. Average velocities from these intervals were then compared using correlational, Bland–Altman analysis, coefficient of variation (CV), and statistical parametric mapping (SPM). Mostly, excellent correlations were observed and ranged from 0.93 to 1.00, 0.53 to 1.00 and 0.93 to 1.00 for the 3, 6, and 9 kg load conditions, respectively. CV values ranged from 0.3 to 3.2%, 0.8 to 4.3%, and 1.5 to 7.7% for the CARvel, COMpelvis_vel, and COMvel comparisons, respectively. The biases for CARvel comparisons ranged from −0.027 to 0.05 m/s, −0.246 to 0.128 m/s and −0.486 to 0.082 m/s across all load conditions and time intervals for the CARvel, COMpelvis_vel, and COMvel comparisons, respectively. SPM analysis indicated significant differences between MRDvel and COMvel and COMpelvis_vel over short time periods during the CoD, but no difference between MRDvel and CARvel. The velocity measurements obtained by a MRD during a m505 test are valid as low biases, low CV’s, and high correlations are observed for the MRDvel to CARvel comparison. As single points of measurement (i.e., laser) has been proven useful to assess other athletic tasks (i.e., sprint running), the single point CARvel comparison is an appropriate comparison for validating MRDvel measurements during the m505 test.

Highlights

Change of direction (CoD) is an important skill in multidirectional sports and identified as an essential component underpinning agility where athletes are required to make quick and precise CoD maneuvers to enable successful tactical and technical outcomes
The observed biases for CARvel comparisons ranged from −0.027 to 0.05 m/s, −0.246 to 0.128 m/s, and −0.486 to 0.082 m/s across all loaded conditions and time intervals for the CARvel, COMpelvis_vel, and center of mass velocity (COMvel) comparisons, respectively (Table 2)
The motorized resistance device (MRD) provided valid velocity measurements as excellent correlation coefficients and coefficient of variation (CV) values indicate a close relationship between motion capture data and MRD velocity (MRDvel) in each phase of the CoD

Summary

Introduction

Change of direction (CoD) is an important skill in multidirectional sports and identified as an essential component underpinning agility where athletes are required to make quick and precise CoD maneuvers to enable successful tactical and technical outcomes. CoD has been defined as “the skills and abilities needed to change movement direction, velocity, or modes” (DeWeese and Nimphius, 2016) where the ability to co-ordinate force application during each phase of CoD including: (1) initial acceleration, (2) deceleration, (3) turn, and (4) re-acceleration is important (Dos’Santos et al, 2017). A plethora of tests are used to quantify CoD based on different movement patterns (i.e., sprint and side shuffle), angle of turn, number of turns, and duration (Nimphius et al, 2017). Such differences make comparisons between tests difficult as CoD is a task-specific skill based on angle of turn and entry velocity (Nimphius et al, 2017; Dos’Santos et al, 2018). Indirect measures, such as the COD deficit, have been developed in an attempt to better quantify CoD ability by isolating the CoD component (Nimphius et al, 2016)

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