Inflammation Following Yo-Yo Level-1 Test with Circadian Timing: The Effect of Time-of-Day on Biomarker Responses

The aim of this study is to investigate the acute effects of the Yo-Yo Intermittent Recovery Test (Level-1) administered in the morning and evening hours on performance, metabolic hormones, and inflammation parameters in soccer players. Thirteen voluntary male soc-cer players (mean age: 23.39 ± 2.5 years) from Tavasbirlik Sports Club, competing in the Denizli Super Amateur League, participated in the study. The Yo-Yo IR1 test was admin-istered to the athletes with a one-week interval in the morning (09:00–11:00) and evening (17:00–19:00). Data were collected via venous blood samples taken Pre-Test (Pre), Post-Test (Post), and 2 Hours Post-Test (2h-Post), along with lactate measurements taken 3 minutes after the completion of the test. According to the findings, the total distance covered in the evening measurements (1655.38 m) was statistically significantly higher than in the morning measurements (1363.07 m) (p