Clin Chem Lab Med 2015; 53(10): e249–e252 *Corresponding author: Rafael Alis, Research Institute “Dr. Viña Giner”, Molecular and Mitochondrial Medicine, Catholic University of Valencia San Vicente Mártir, C/ Quevedo 2, 46001 Valencia, Spain, Phone: + 34 963637412, Fax: +34 963944590, E-mail: rafael.alis@ucv.es; and School of Medicine, Catholic University of Valencia San Vicente Mártir, Valencia, Spain Fabian Sanchis-Gomar: Research Institute of the Hospital 12 de Octubre (“i+12”), Madrid, Spain Davide Ferioli and Antonio La Torre: Department of Biomedical Sciences for Health, Università degli Studi di Milano, Milan, Italy. Andrea Bosio and Ermanno Rampinini: Human Performance Laboratory, MAPEI Sport Research Center, Olgiate Olona (VA), Italy Jincheng Xu: Sport Rehabilitation Department, Beijing Sport University, Beijing, P.R. China Giovanni Lombardi: Laboratory of Experimental Biochemistry & Molecular Biology, I.R.C.C.S. Istituto Ortopedico Galeazzi, Milan, Italy Marco Romagnoli: Research Institute “Dr. Viña Giner”, Molecular and Mitochondrial Medicine, Catholic University of Valencia San Vicente Mártir, Valencia, Spain; and Department of Physical Education and Sports, University of Valencia, Valencia, Spain Letter to the Editor Rafael Alis*, Fabian Sanchis-Gomar, Davide Ferioli, Antonio La Torre, Andrea Bosio, Jincheng Xu, Giovanni Lombardi, Marco Romagnoli and Ermanno Rampinini Association between physical fitness and mean platelet volume in professional soccer players DOI 10.1515/cclm-2014-1275 Received December 24, 2014; accepted January 8, 2015; previously published online April 14, 2015 Keywords: platelet activation; sports performance; team sports. To the Editor, Platelets play an important role in the formation of blood clots and atheromatous plaques by adhering to damaged endothelium and releasing the content of their granules. Consequently, platelet hyper-aggregation and -activation are involved in the onset of atherosclerosis, and hence, in cardio- vascular diseases (CVD), myocardial infarction and stroke [1]. It is now well known that hemostasis is directly implicated in the health benefits of regular exercise and physical activity. In fact, regular practice of exercise reduces platelet aggrega- bility, decreases clotting factors and enhances fibrinolysis which altogether provoke hypocoagulability [2]. Interestingly, it has been recently shown that the baseline platelet size, conventionally expressed as mean platelet volume (MPV), may be negatively associated with the time to complete a half-marathon race, being a predic- tor of endurance performance [3]. MPV is routinely determined, along with others parameters, in automated hematological analyzers as a marker of platelet activation and/or reactivity. Accord- ingly, it could be used as an easy and inexpensive bio- marker of physical performance in other exercise settings [4]. In this study, we aimed to prove whether MPV might be associated with physical fitness in professional soccer players throughout a competitive season. To this aim, 15 male professional soccer players from an Italian Serie A team (age 27±5 years, weight 76.9±4.1 kg, height 1.82±0.05 m) were included in this study. Goal- keepers were excluded from the study because their total distance covered and running intensities during soccer matches highly differ from those experienced by the field players. The players were controlled two times during the end-part of the professional soccer season (at January and at March). The competitive season finished at the end of May. Thereafter, all players took vacation time and returned to the team discipline at the beginning of July, when the players included in the study were sampled again. The study, which complies with the World Medical Association Declaration of Helsinki regarding ethical conduct of research involving human subjects and/or animals, was approved by the Ethics Committee of Uni- versity of Valencia and by the soccer club involved. At all time-points, the samples were drawn at the same hour (between 7 and 8 a.m.) in fasting conditions, and carried to the laboratory within the same time-frame. Hematological parameters (RBC count, hemoglobin, hematocrit, WBC count, neutrophils count, MPV and platelet count) were determined in an automated hema- tological analyzer (XE-2100L, Sysmex, Kobe, Japan). Biochemical parameters [lactate dehydrogenase (LDH), creatine kinase (CK), cortisol and testosterone] were also determined. Brought to you by | Università degli Studi di Milano Authenticated Download Date | 10/20/15 2:08 PM