Quantifying technical actions in professional soccer using foot-mounted inertial measurement units

Marris, Joshua B.

Sports science
September 2021

Thesis or dissertation


Rights
© 2021 Joshua B Marris. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright holder.
Abstract

This thesis aimed to (i) establish the concurrent validity and intra-unit reliability of a foot-mounted inertial measurement unit (IMU), for measuring the frequency of technical actions performed during soccer training activities, and (ii) to quantify the within-microcycle, inter-positional, and between-drill differences in the technical actions of professional soccer training using foot-mounted IMUs.
Twelve male amateur soccer players collectively performed 8,640 ball touches and 5,760 releases, throughout a series of technical soccer tasks, repeated over two pre-determined distances. Concurrent validity was determined by calculating the proportion of agreement (PA) between the IMU and retrospective video analyses. Intra-unit reliability was established using the same method, supplemented by a percentage coefficient of variation (CV). Intra-operator reliability of the reference performance analyst, who conducted all analyses, was established by manually coding three randomly selected repetitions of each soccer task three times (PA = 100.0%). The IMU exhibited good concurrent validity (PA = 95.1% - 100.0%) and intra-unit reliability (PA = 95.9% - 96.9%, CV = 1.4% - 2.9%) for measuring ball touches and releases throughout all experimental conditions.
Twenty-one male professional soccer players’ technical performance data (ball touches, releases, ball touches per minute, releases per minute), collected during training sessions throughout 24 weekly microcycles (i.e., match day [MD] minus day number [MD - n]), was subsequently analysed using general linear modelling. The most ball touches (X = 218.0) and releases (X = 110.8) were observed on MD - 1, with MD - 5 eliciting the highest frequency of ball touches per minute (X = 3.8) and releases per minute (X = 1.7). Central midfielders performed the most ball touches (X = 221.9), releases (X = 108.3), ball touches per minute (X = 3.4), and releases per minute (X = 1.6). Small-sided games evoked more ball touches per minute (Xdiff = 1.5), and releases per minute (Xdiff = 0.1), than previously reported in match-play. The fewest ball touches per minute (X = 1.2) and releases per minute (X = 0.5) were observed during tactical drills. The results of this thesis indicate that the foot-mounted IMU displayed promising capacity as a valid and reliable method of quantifying technical actions in soccer, as well as providing a novel understanding of the within-microcycle, inter-positional, and between-drill differences in the technical actions performed by professional players during training.

Publisher
Department of Sport, Health & Exercise Science, The University of Hull
Supervisor
Towlson, Christopher; Abt, Grant; Barrett, Steve (Sport scientist)
Qualification level
Masters
Qualification name
MSc
Language
English
Extent
6 MB
Identifier
hull:18389
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