Stability in post-seasonal hematological profiles in response to high-competitive match-play loads within elite top-level European soccer players: implications from a pilot study

Adam L Owen,1,2 Marco A Cossio-Bolaños,3,4 Gordon Dunlop,1 Mehdi Rouissi,5 Moktar Chtara,5 Nicola Luigi Bragazzi,6 Karim Chamari7 1Servette Centre for Football Research (SCFR), Servette Football Club, Geneva, Switzerland; 2Centre de Recherche et d’Innovation sur le Sport, Université Claude Bernard Lyon.1, Lyon,  France; 3Faculty of Physical Education, State University of Campinas, Sao Paulo, Brazil; 4Department of Physical Activity Sciences, Catholic University of Maule, Talca, Chile; 5Tunisian Research Laboratory, National Centre of Medicine and Science in Sport, Tunis, Tunisia; 6Department of Health Sciences (DISSAL), School of Public Health, University of Genoa, Genoa, Italy; 7Athlete Health and Performance Research Centre, ASPETAR, Qatar Orthopedic and Sports Medicine Hospital, Doha, Qatar Introduction: The stability of hematological status indices is a key determinant of optimal sport performance. The capacity to monitor hematological behaviors of elite soccer players may better explain the stresses placed upon physiological systems and the potential decrements in performance and physical capacity. The primary aim of this investigation was to examine the post-seasonal hematological status of professional top-level soccer players in response to seasonal match-play and training demands, in terms of the training practices, intensity, and loadings that they experience before, during, and after each season. Methods: Seventeen male elite European soccer players participated in the study (mean±SD: age 26.8±4.6 years, weight 78.1±5.7 kg, height 182.4±4.8 cm, body fat 9.8%±2.9%, and maximal aerobic capacity 56.5±4.2 mL kg−1 min−1). The season culminated in 74 competitive matches including domestic, Champions League, and UEFA Cup matches. Blood samples were collected between 9:00 and 10:30 am after an overnight fast (~10 hours)