Extensive Monitoring Through Multiple Blood Samples in Professional Soccer Players

Abstract

The aim of this study was to make a comprehensive gathering of consecutive detailed blood samples from professional soccer players and to analyze different blood parameters in relation to seasonal changes in training and match exposure. Blood samples were collected 5 times during a 6-month period and analyzed for 37 variables in 27 professional soccer players from the best Danish league. Additionally, the players were tested for body composition, V[Combining Dot Above]O2max and physical performance by the Yo-Yo intermittent endurance submax test (IE2). Multiple variations in blood parameters occurred during the observation period, including a decrease in hemoglobin and an increase in hematocrit as the competitive season progressed. Iron and transferrin were stable, whereas ferritin showed a decrease at the end of the season. The immunoglobulin A (IgA) and IgM increased in the period with basal physical training and at the end of the season. Leucocytes decreased with increased physical training. Lymphocytes decreased at the end of the season. The V[Combining Dot Above]O2max decreased toward the end of the season, whereas no significant changes were observed in the IE2 test. The regular blood samples from elite soccer players reveal significant changes that may be related to changes in training pattern, match exposure, or length of the match season. Especially the end of the preparation season and at the end of the competitive season seem to be time points were the blood-derived values indicate that the players are under excessive physical strain and might be more subjected to a possible overreaching-overtraining conditions. We suggest that regular analyses of blood samples could be an important initiative to optimize training adaptation, training load, and game participation, but sampling has to be regular, and a database has to be built for each individual player.

Iron status markers are only transiently affected by a football game

“…Thus, iron deficiency may diminish exercise capacity that ultimately will compromise players' ability to maximise training and competition performances (Beard, 2001). Although fluctuations in iron's status during a football season have been investigated to some degree previously (Banfi & Del Fabbro, 2007;Heisterberg et al, 2013;Reinke et al, 2012), the short-term temporal changes of iron status in response to a football match are yet to be determined. Therefore, the aim of this study was to examine the time-dependent responses of iron's status markers in response to a football match and training.…”

Fatigue and Recovery in Soccer: Evidence and Challenges

“…Soccer causes an increase in metabolism with significant hematological changes [96,145], thus information from biomarkers could be used to optimize training adaptation, training load, and match participation [83,145,146]. Biomarkers responses are influenced by several factors and reflect multiple interactions, so interpretation must be cautious [147].…”

A comparison of competitive profiles across the Spanish football leagues

“…The value, in the men's 1st, 2nd, and 2nd B divisions, with a high percentage of matches with tied scores or scores with moderately low differences between the points achieved in the final standings by the teams, demonstrates that this macro-group of Championships, in comparison with the other macrogroup (IPCs), is characterized by its correspondence with competitive profiles with a high level of equality and competitiveness. From our perspective, the aforementioned differences could be justified if we consider questions related to the application of more demanding playerselection processes in the HPCs versus the IPCs (Dellal et al, 2011b;Ingebrigtsen et al, 2012;Heisterberg et al, 2013); the presences of a higher degree of qualification and technicaltactical, physical, and physiological homogeneity observed in the players belonging to the HPCs in comparison with those belonging to the IPCs (Costa, Garganta, Greco, Mesquita & Afonso, 2010;Dellal et al, 2011a;Salinero et al, 2013;Bradley et al, 2013); the availability of a more extensive and homogeneous offering of infrastructure (installations, materials, and equipment) and human resources (trainers, doctors, physical-therapists, etc.) within reach of the teams belonging to the HPCs in comparison with those belonging to the IPCs, and additionally, the more systematic and regular exposure of players associated with the HPCs with respect to the IPCs to high-quality training programs and methodological specificity (Vales-Vázquez et al, 2017).…”