Quantification of the physical demands of training and match-play in elite youth soccer players

Kyprianou, E (2026) Quantification of the physical demands of training and match-play in elite youth soccer players. Doctoral thesis, Liverpool John Moores University.

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Abstract

A detailed understanding of the relationship between external and internal training load (dose-response) is crucial for the effective optimisation of athletic performance (Impellizzeri et al., 2019). To date, limited attention has focused on the validity of measurement tools frequently used to quantify the demands of training and match-play in soccer. The purpose of the thesis was to examine the validity of these measurement tools using elite youth soccer players.
Using elite youth soccer players’ maximal sprinting speeds (MSS) collected from a criterion and non-criterion measure, the aim of the first study (chapter 3) was to demonstrate how practitioner opinion can be used to determine measurement validity. Twelve elite youth soccer players performed two maximal 40 m sprints, measured by 10-Hz GPS units (non-criterion) and a 100-Hz Laser (criterion). Setting statistical equivalence bounds as practitioner opinion of the practically acceptable amount of measurement error
for MSS, the agreement between GPS and Laser was assessed. MSS was 8.79 ± 0.33 m/s (Laser) and 8.75 ± 0.32 m/s (GPS), and the mean difference was 0.04 (90% confidence interval -0.03 to 0.11) m/s. Equivalence testing showed Laser and GPS as likely equivalent
measures (probability 93.7%). Using an analytical method informed by expert opinion on the acceptable amount of measurement error for MSS, practitioners can rely on GPS for an accurate assessment of MSS.
The aim of the second study (chapter 4) was to investigate whether players’ MSS occurs during sprint testing or typical soccer training activities and competitive matches. The MSS of 12 full-time male youth soccer players was recorded during a 40-m sprint test and their routine activities (matches, sprints, and skill-based conditioning drills: small-sided games [SSG], medium-sided games [MSG], large-sided games [LSG]). All activities were monitored with 10-Hz GPS, with the highest speed attained during each activity retained as the instantaneous MSS. MSS was faster for the sprint test (8.76 ± 0.39 m·s-1) compared with matches (7.94 ± 0.49 m·s-1), LSG (6.94 ± 0.65 m·s-1), MSG (6.40 ± 0.75 m·s-1), and SSG (5.25 ± 0.92 m·s-1), but not sprints (8.50 ± 0.36 m·s-1). These findings highlight the importance of 40-m sprint testing to assess players' MSS and suggest that practitioners
should incorporate specific sprint drills with adequate space (e.g., 40 meters) during purposeful sprint training to expose players to MSS stimuli. The aim of the third study (chapter 5) was to examine the moderating effect of familiarisation on the relationship between proxy measures of external load and ratings of perceived exertion (RPE) in elite youth soccer players. The final sample included familiarised (blackness test; n= 20) and non-familiarised players (n= 15) with the Borg centiMax scale; players were monitored over a 31-week period. Global RPE and dRPE for breathlessness (RPE-B) and leg-muscle exertion (RPE-L) were recorded 15 to 30 minutes following training sessions and match-play. Players improved their blackness test score from 39% to 78%. For explorations by number of accelerations, familiarisation effects were not practically relevant for the global RPE and RPE-B variables. The width and sign of the effects for the RPE-L variable at 30 efforts of 10 au (95% CI, 4-16 au) suggested that scores were lower for players who underwent familiarisation versus players who did not. Familiarisation effects were not practically relevant for any RPE variable irrespective of
the number of deceleration efforts and high-speed running (HSR) covered. These data indicate that improved performance on the blackness test did not have a moderating effect on the relationship between proxy measures of external load and RPE. The aim of the fourth and final study (chapter 6) was twofold. First, to assess the between-method agreement for the quantification of HSR distance by comparing absolute and relative speed threshold approaches. Secondly, to investigate the associations between internal and external load (dose-response relationship), using session type-specific differences in perceived exertion (RPE, dRPE) at pre-specified values of absolute and
relative HSR distance in elite youth soccer players. The final sample consisted of thirteen elite youth soccer players who completed approximately five training sessions per week over a 31-week period. The use of relative HSR thresholds resulted in consistently lower
median HSR distances compared to absolute thresholds across strength (176 m vs. 168 m), endurance (268 m vs. 247 m), and speed (173 m vs. 146 m) sessions. For explorations with global RPE as response variable, visual inspection of the density
strips surrounding the mean estimate suggested no effect clearly exceeded the predefined region of equivalence regardless of the HSR quantification method. The mean difference in global RPE for game versus endurance session type comparison was 11 au (95%CI, 3 to 18 au) at 500 m of absolute HSR. Game versus speed session type mean differences in global RPE by absolute and relative HSR at 500 m were 11 au (95%CI, 3 to 19 au) and 12 au (95%CI, 3 to 20 au), respectively. For explorations with RPE-B as response variable, density strips suggested most of the estimated effects were broadly uncertain and not
practically relevant. For explorations with RPE-L as response variable, density strips indicated some clear and practically relevant effects mostly at HSR distances of 500 m. For instance, at absolute HSR of 500 m, mean differences in RPE-L for game versus endurance
and game versus speed session type comparisons were 15 au (95%CI, 4 to 27 au) and 14au (95%CI, 4 to 24 au), respectively. The results presented demonstrated that global RPE in response to external load remained similar whether analysed using absolute or relative speed zones and did not change across the different type of training sessions. RPE-L exhibits greater sensitivity to variations across different training modes compared to RPE-B. However, both measures maintain a strong association with global RPE. Notably, this
relationship persists regardless of whether external load is assessed using absolute or individualised speed thresholds. The results of this thesis provide novel insights into the quantification of the physical
demands of training and match-play in elite youth soccer players. The data demonstrate the validity of GPS-based speed measurements and highlight important contextual considerations for sprint performance assessment. Finally, information was presented on the associations between internal and external load (dose-response) in elite youth soccer
players, suggesting that global RPE remains a valid and efficient tool for monitoring internal responses to external training loads. Practitioners can confidently implement global RPE in daily training environments without the need for additional differential RPE measures.

Item Type:	Thesis (Doctoral)
Uncontrolled Keywords:	training load; soccer; youth
Subjects:	G Geography. Anthropology. Recreation > GV Recreation Leisure > GV561 Sports
Divisions:	Sport and Exercise Sciences
Date of acceptance:	1 June 2026
Date of first compliant Open Access:	26 May 2026
Date Deposited:	26 May 2026 13:39
Last Modified:	02 Jun 2026 15:02
DOI or ID number:	10.24377/LJMU.t.00028581
Supervisors:	McRobert, A, Lorenzo, L and Gregson, W
URI:	https://researchonline.ljmu.ac.uk/id/eprint/28581

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