ResearchArticle Relationships between Fitness Status and Blood Biomarkers in Professional Soccer Players Ana Filipa Silva , 1,2,3 Francisco Tom´ asGonz´ alez-Fern´ andez, 4 Halil Ibrahim Ceylan, 5 Rui Silva, 1,2 Saeid Younesi, 6 Yung-Sheng Chen, 7 Georgian Badicu , 8 Pawel Wola´ nski, 9 Eugenia Murawska-Cialowicz, 10 and Filipe Manuel Clemente 1,11 1 Escola Superior Desporto e Lazer, Instituto Polit´ ecnico de Viana Do Castelo, Viana do castelo, Portugal 2 Research Center in Sports Performance, Recreation Innovation and Technology (SPRINT), Melgaço 4960-320, Portugal 3 e Research Centre in Sports Sciences, Health Sciences and Human Development (CIDESD), Vila Real 5001-801, Portugal 4 Department of Physical Education and Sport, Faculty of Education and Sport Sciences, Campus of Melilla, University of Granada, 52006 Melilla, Spain 5 Physical Education and Sports Teaching Department, Kazim Karabekir Faculty of Education, Ataturk University, Erzurum, Turkey 6 University of Coimbra, Research Unit for Sport and Physical Activity, Faculty of Sport Sciences and Physical Education, Coimbra 3004-531, Portugal 7 Department of Exercise and Health Sciences, University of Taipei, Taipei 11153, Taiwan 8 Department of Physical Education and Special Motricity, Transilvania University of Brasov, Brasov 500068, Romania 9 Department of Physiology, Gdansk University of Physical Education and Sport, Gdansk 80-336, Poland 10 Department of Physiology and Biochemistry, University School of Physical Education, Wrocław 51-612, Poland 11 Instituto de Telecomunicações, Delegação da Covilhã, Lisboa 1049-001, Portugal Correspondence should be addressed to Georgian Badicu; georgian.badicu@unitbv.ro Received 20 December 2021; Revised 11 February 2022; Accepted 7 March 2022; Published 11 April 2022 AcademicEditor:RedhaTaiar Copyright © 2022 Ana Filipa Silva et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Background. Physical conditions are recognized to be optimal after the pre-season (PS) phase in professional sports. Given that bloodmeasuresmayalsorevealvariations,whichinturn,maypresentassociationswithfitnesschanges. Objective.eaimofthis study is to test the changes of blood markers and physical fitness outcomes at the beginning and following the PS phase. Additionally, we aimed also to analyze the associations of training adaptations between blood markers and the physical fitness measures. Methodology.25professionalmalesoccerplayers(28.1 ± 4.6yearsold,2.0 ± 7.8kg,and176.7 ± 4.9cm)wereassessedfor hematological and biochemical parameters, and physical fitness measures in the baseline and after the phase of PS. Results. Increases in platelets were observed after the PS phase (p � 0.001, η2 � 0.39). Regarding the biochemical parameters, significant increases between PS were found for creatinine (Cre) (p � 0.001, η2 � 0.66), alkaline phosphatase (ALP) (p � 0.001, η2 � 0.79), C-Reactive Protein (CRP) (p � 0.001, η2 � 0.74), cortisol (C) (p � 0.001, η2 � 0.63), and testosterone (T)(p � 0.001, η2 � 0.76), whereas significant decreases were found for albumin (Alb) (p � 0.004, η2 � 0.29), and calcium corrected (Ca Corr.) (p � 0.002, η2 � 0.32).Moderatecorrelationswerefoundbetweenalbuminandthe5-meterlinearsprintsplit(r � –0.44(95%CI:–0.71;–0.05)) andCRP(r � –0.48(95%CI:–0.74;–0.10)).ModeratecorrelationswerefoundbetweenVAMEVALandhemoglobin(r � 0.44(95% CI: 0.05; 0.71)). Conclusions. e overall physical fitness measures improved after the PS phase. Also, significant variations (decreases/increases)wereobservedforthecaseofbiomchemicalandhematologicaloutcomes.Coachesshouldcarefullyconsider the adaptative changes observed in blood parameters as the changes in whole organism and metabolism after specific critical phasesasthePSinprofessionalplayers.us,optimalmanagementofstimulus/recoverycanbewarrantedtominimizeillnessand injury rate and to follow the direction and dynamics of adaptative changes. Hindawi Journal of Healthcare Engineering Volume 2022, Article ID 5135817, 13 pages https://doi.org/10.1155/2022/5135817