Abstract
PurposeOur aims were to examine (i) the internal load during simulated soccer match-play by elite youth players; and (ii) the time-course of subsequent recovery from perceived and performance fatigability.MethodsEleven male youth players (16 ± 1 years, 178 ± 7 cm, 67 ± 7 kg) participated in a 2 × 40-min simulated soccer match, completing 30 rounds (160 s each) with every round including multidirectional and linear sprinting (LS20m), jumping (CMJ) and running at different intensities. During each round, LS20m, CMJ, agility, heart rate (HR), oxygen uptake (VO2), energy expenditure (EE), substrate utilization and perceived exertion RPE were assessed. In addition, the blood level of lactate (Lac) was obtained after each of the five rounds. Creatine kinase (CK) concentration, maximal voluntary isometric knee extension and flexion, CMJ, number of skippings in 30 s, and subjective ratings on the Acute Recovery and Stress Scale (ARSS) were examined before and immediately, 24 and 48 h after the simulation.ResultsDuring the game %HRpeak (p < 0.05, d = 1.08), %VO2peak (p < 0.05; d = 0.68), Lac (p < 0.05, d = 2.59), RPEtotal (p < 0.05, d = 4.59), and RPElegs (p < 0.05, d = 4.45) all increased with time during both halves (all p < 0.05). Agility improved (p < 0.05, d = 0.70) over the time-course of the game, with no changes in LS20m (p ≥ 0.05, d = 0.34) or CMJ (p ≥ 0.05, d = 0.27). EE was similar during both halves (528 ± 58 vs. 514 ± 61 kcal; p = 0.60; d = 0.23), with 62% (second half: 65%) carbohydrate, 9% (9%) protein and 26% (27%) fat utilization. With respect to recovery, maximal voluntary knee extension (p ≥ 0.05, d = 0.50) and flexion force (p ≥ 0.05, d = 0.19), CMJ (p ≥ 0.05, d = 0.13), number of ground contacts (p ≥ 0.05, d = 0.57) and average contact time (p ≥ 0.05, d = 0.39) during 30-s of skipping remained unaltered 24 and 48 h after the game. Most ARSS dimensions of load (p < 0.05, d = 3.79) and recovery (p < 0.05, d = 3.22) returned to baseline levels after 24 h of recovery. Relative to baseline values, CK was elevated immediately and 24 h after (p < 0.05, d = 2.03) and normalized 48 h later.ConclusionIn youth soccer players the simulated match evoked considerable circulatory, metabolic and perceptual load, with an EE of 1042 ± 118 kcal. Among the indicators of perceived and performance fatigability examined, the level of CK and certain subjective ratings differed considerably immediately following or 24–48 h after a 2 × 40-min simulated soccer match in comparison to baseline. Accordingly, monitoring these variables may assist coaches in assessing a U17 player’s perceived and performance fatigability in connection with scheduling training following a soccer match.
Highlights
In connection with their continuous efforts to improve performance, athletes are limited by the perceived and performance fatigability determined by their own physical and cognitive capacities (Enoka and Duchateau, 2016)
To the best of our knowledge, corresponding characterization of a youth soccer match has not yet been reported and such information could assist with optimal energy intake during the match and breaks
This study was designed in accordance with the Declaration of Helsinki and approved by the institute’s ethical review board
Summary
In connection with their continuous efforts to improve performance, athletes are limited by the perceived and performance fatigability determined by their own physical and cognitive capacities (Enoka and Duchateau, 2016). With respect to intra-match assessment of internal and external loads far less is known concerning youth compared to adult soccer players. In the latter, acute fatigue is related, at least in part, to the aerobic and anaerobic metabolic processes, such as depletion of glycogen stores (Mohr et al, 2003; Di Salvo et al, 2009), involved in elevating EE, with an average EE of 14.6 [as measured by video analysis (Osgnach et al, 2010)] to 16.8 and 18.1 kcal·kg−1 [determined by gas exchange (Bangsbo, 1994a; Ferrauti et al, 2006)]. To the best of our knowledge, corresponding characterization of a youth soccer match has not yet been reported and such information could assist with optimal energy intake during the match and breaks
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