The Tracking of Morning Fatigue Status Across In-Season Training Weeks in Elite Soccer Players.

PURPOSE: To quantify the mean daily changes in training and match load and any parallel changes in indicators of morning-measured fatigue across in-season training weeks in elite soccer players. METHODS: Following each training session and match, ratings of perceived exertion (s-RPE) were recorded to calculate overall session load (RPE-TL) in 29 English Premier League players from the same team. Morning ratings of fatigue, sleep quality, delayed-onset muscle soreness (DOMS), as well as sub-maximal exercise heart rate (HRex), post-exercise heart rate recovery (HRR%) and variability (HRV) were also recorded pre-match day and one, two and four days post-match. Data were collected for a median duration of 3 weeks (range:1-13) and reduced to a typical weekly cycle including no mid-week match and a weekend match day. Data were analysed using within-subjects linear mixed models. RESULTS: RPE-TL was approximately 600 AU (95%CI: 546-644) higher on match-day vs the following day (P0.05). CONCLUSIONS: Morning-measured ratings of fatigue, sleep quality and DOMS are clearly more sensitive than HR-derived indices to the daily fluctuations in session load experienced by elite soccer players within a standard in-season week

Visual Function of English Premier League Soccer Players

Purpose: Examine visual function of soccer players of different skill level and playing position. Methods: Elite players from an English Premier League soccer club (n=49) and intermediate players (n=31) completed an assessment on a Nike SPARQ Sensory Station of: static and dynamic visual acuity, contrast sensitivity, accommodative-vergence facility, target capture and perception span. Results: There was no difference between elite and intermediate players for all measures. However, competitive soccer players (elite, intermediate) did exhibit better performance in acuity-based measures of visual function and accommodative-vergence compared to a population of healthy non-athletic adults (n=230). With regards to player position, defensive players showed quicker accommodative-vergence facility compared to offensive players. Conclusion: Visual function of competitive soccer players is superior to non-athletic adults, but does not differentiate the elite and intermediate player. However, defensive players do exhibit faster accommodative-vergence than offensive players. We suspect that this particular visual function is advantageous for defenders given the greater demand to continually shift gaze between players located at near and far locations

The Influence of Changes in Acute Training Load on Daily Sensitivity of Morning-measured Fatigue Variables in Elite Soccer Players.

PURPOSE: To determine the sensitivity of a range of potential fatigue measures to daily training load accumulated over the previous two, three and four days during a short in-season competitive period in elite senior soccer players (n=10). METHODS: Total high-speed running distance, perceived ratings of wellness (fatigue, muscle soreness, sleep quality), counter-movement jump height (CMJ), submaximal heart rate (HRex), post-exercise heart rate recovery (HRR) and heart rate variability (HRV: Ln rMSSD) were analysed during an in-season competitive period (17 days). General linear models were used to evaluate the influence of two, three and four day total high-speed running distance accumulation on fatigue measures. RESULTS: Fluctuations in perceived ratings of fatigue were correlated with fluctuations in total high-speed running distance accumulation covered on the previous 2-days (r=-0.31; small), 3 -days (r=-0.42; moderate) and 4-days (r=-0.28; small) (p<0.05). Changes in HRex (r=0.28; small; p= 0.02) were correlated with changes in 4-day total high-speed running distance accumulation only. Correlations between variability in muscle soreness, sleep quality, CMJ, HRR% and HRV and total high-speed running distance were negligible and not statistically significant for all accumulation training loads. CONCLUSIONS: Perceived ratings of fatigue and HRex were sensitive to fluctuations in acute total high-speed running distance accumulation, although, sensitivity was not systematically influenced by the number of previous days over which the training load was accumulated. The present findings indicate that the sensitivity of morning-measured fatigue variables to changes in training load is generally not improved when compared with training loads beyond the previous days training

Monitoring of post-match fatigue in professional soccer: Welcome to the real world

Participation in soccer match-play leads to acute and transient subjective, biochemical, metabolic and physical disturbances in players over subsequent hours and days. Inadequate time for rest and regeneration between matches can expose players to the risk of training and competing whilst not entirely recovered. In professional soccer, contemporary competitive schedules can require teams to compete in-excess of 60 matches over the course of the season while periods of fixture congestion occur prompting much attention from researchers and practitioners to the monitoring of fatigue and readiness to play. A comprehensive body of research has investigated post-match acute and residual fatigue responses. Yet the relevance of the research for professional soccer contexts is debatable notably in relation to the study populations and designs employed. Monitoring can indeed be invasive, expensive, time-inefficient and difficult to perform routinely and simultaneously in a large squad of regularly competing players. Uncertainty also exists regarding the meaningfulness and interpretation of changes in fatigue response values and their functional relevance, and practical applicability in the field. The real-world need and cost-benefit of monitoring must be carefully weighed up. In relation to professional soccer contexts, this opinion paper intends to: 1) debate the need for PMF monitoring, 2) critique the real-world relevance of the current research literature, 3) discuss the practical burden relating to measurement tools and protocols and the collection, interpretation and application of data in the field, and, 4) propose future research perspectives