{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,12]],"date-time":"2026-03-12T04:03:13Z","timestamp":1773288193037,"version":"3.50.1"},"reference-count":48,"publisher":"Canadian Science Publishing","issue":"4","license":[{"start":{"date-parts":[[2014,4,1]],"date-time":"2014-04-01T00:00:00Z","timestamp":1396310400000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/www.nrcresearchpress.com\/page\/about\/CorporateTextAndDataMining"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Appl. Physiol. Nutr. Metab."],"published-print":{"date-parts":[[2014,4]]},"abstract":"<jats:p>This study aimed to analyze changes in performance, muscle function, and stress-related biochemical markers in professional soccer players (n = 14) at 4 timepoints (3 for performance and 4 for stress-related biochemical markers) during the soccer season [Formula: see text] preseason (E1), midseason (E2), end of the season (E3) [Formula: see text] and after the end of the recovery period (E4). Performance in 5- and 30-m sprints, countermovement jump, and agility, and maximal isokinetic knee extension and knee flexion strength were measured (E1 to E3). We observed increased in-season levels of myoglobin (E2 &gt; E1 and E4; p &lt; 0.05), a higher testosterone\/cortisol ratio (T\/C), and increased levels of creatine kinase (CK), C-reactive protein, superoxide dismutase (SOD), protein sulfhydryls (\u2013SH), and malondialdehyde (E2 and E3 &gt; E1 and E4; p &lt; 0.05). Lower cortisol concentrations (E3 &lt; E1 and E4; p &lt; 0.05) and glutathione reductase activity (E3 &lt; E2 and E4; p &lt; 0.05) were observed at the end of the season. T\/C, CK, SOD, \u2013SH, and malondialdehyde decreased during the off-season, and cortisol and glutathione reductase increased (E3 &lt; E4; p &lt; 0.05). Agility increased in E2 and E3 (p &lt; 0.01). Significant correlations were found during the season between hormonal and muscle function parameters (r = 0.56\u20130.86; p &lt; 0.05). In addition, in E2, significant associations were observed between match-accumulated time (MAT<jats:sub>E2<\/jats:sub>; minutes played by each player during the competition period), performance, and hormonal and redox parameters (r = 0.456\u20130.615; p &lt; 0.05). In conclusion, this study shows that soccer players face significant changes in biomarkers of physiologic strain (muscle damage and oxidative stress-related markers) during the season, but values return to normal during the off-season. Additionally, MAT influences physical, hormonal, and oxidative stress-related parameters in professional soccer players.<\/jats:p>","DOI":"10.1139\/apnm-2013-0180","type":"journal-article","created":{"date-parts":[[2013,10,28]],"date-time":"2013-10-28T21:35:55Z","timestamp":1382996155000},"page":"432-438","source":"Crossref","is-referenced-by-count":91,"title":["Biochemical impact of soccer: an analysis of hormonal, muscle damage, and redox markers during the season"],"prefix":"10.1139","volume":"39","author":[{"given":"Jo\u00e3o Renato","family":"Silva","sequence":"first","affiliation":[{"name":"Center of Research, Education, Innovation and Intervention in Sport (CIFI2D), Rua Dr. Pl\u00e1cido Costa, 91, 4200-450 Porto, Portugal."},{"name":"National Sports Medicine Programme Excellence in Football Project, Aspetar-Qatar Orthopaedic and Sports Medicine Hospital, Doha, Qatar."}]},{"given":"Ant\u00f3nio","family":"Rebelo","sequence":"additional","affiliation":[{"name":"Center of Research, Education, Innovation and Intervention in Sport (CIFI2D), Rua Dr. Pl\u00e1cido Costa, 91, 4200-450 Porto, Portugal."}]},{"given":"Franklim","family":"Marques","sequence":"additional","affiliation":[{"name":"Institute for Molecular and Cell Biology (IBMC), University of Porto, Porto, Portugal."}]},{"given":"Laura","family":"Pereira","sequence":"additional","affiliation":[{"name":"Institute for Molecular and Cell Biology (IBMC), University of Porto, Porto, Portugal."}]},{"given":"Andr\u00e9","family":"Seabra","sequence":"additional","affiliation":[{"name":"Research Center in Physical Activity, Health and Leisure (CIAFEL), Portugal; Rua Dr. Pl\u00e1cido Costa, 91, 4200-450 Porto, Portugal."}]},{"given":"Ant\u00f3nio","family":"Ascens\u00e3o","sequence":"additional","affiliation":[{"name":"Research Center in Physical Activity, Health and Leisure (CIAFEL), Portugal; Rua Dr. Pl\u00e1cido Costa, 91, 4200-450 Porto, Portugal."}]},{"given":"Jos\u00e9","family":"Magalh\u00e3es","sequence":"additional","affiliation":[{"name":"Research Center in Physical Activity, Health and Leisure (CIAFEL), Portugal; Rua Dr. Pl\u00e1cido Costa, 91, 4200-450 Porto, Portugal."}]}],"member":"155","reference":[{"key":"refg1\/ref1","doi-asserted-by":"publisher","DOI":"10.1249\/mss.0b013e31815b8497"},{"key":"refg2\/ref2","doi-asserted-by":"publisher","DOI":"10.1017\/S0007114510002394"},{"key":"refg3\/ref3","doi-asserted-by":"publisher","DOI":"10.1155\/2012\/960363"},{"key":"refg4\/ref4","doi-asserted-by":"publisher","DOI":"10.1007\/s00421-005-0104-6"},{"key":"refg5\/ref5","doi-asserted-by":"crossref","first-page":"63","DOI":"10.1111\/j.1600-0838.1996.tb00073.x","volume":"6","author":"Bloomfield J.","year":"2007","journal-title":"J. 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