title: Effects of time-of-day on oxidative stress, cardiovascular parameters, biochemical markers, and hormonal response following level-1 Yo-Yo intermittent recovery test.
abstract: The aim of this study was to investigate the effect of time-of-day on oxidative stress, cardiovascular parameters, muscle damage parameters, and hormonal responses following the level-1 Yo-Yo intermittent recovery test (YYIRT). A total of 11 healthy subjects performed an intermittent test (YYIRT) at two times-of-day (i.e., 07:00 h and 17:00 h), with a recovery period of ≥36 h in-between, in a randomized order. Blood samples were taken at the rest (baseline) and immediately (post-YYIRT) after the YYIRT for measuring oxidative stress, biochemical markers, and hormonal response. Data were statistically analyzed using one-way and two-way repeated measures ANOVA and Bonferroni test at p < 0.05. Observed power (α = 0.05) and partial eta-squared were used. Our results showed that oxygen uptake (VO2max), maximal aerobic speed, and the total distance covered tended to be higher in the evening (17:00 h). There was also a main effect of time-of-day for cortisol and testosterone concentration, which were higher after the YYIRT in the morning (p < 0.05). The heart rate peak and the rating of perceived exertion scales were lower in the morning (p < 0.05). However, the plasma glucose (p < 0.01), malondialdehyde, creatine kinase (p < 0.01), lactate dehydrogenase (p < 0.05), high-density lipoprotein (p < 0.01), total cholesterol (p < 0.01), and triglycerides (p < 0.05) were higher after the YYIRT in the evening. Low-density lipoprotein, systolic blood pressure, diastolic blood pressure, and lactate levels (p > 0.05) were similar for the morning and evening test. In conclusion, our findings suggest that aerobic performance presents diurnal variation with great result observed in the evening accompanied by an improvement of hormonal, metabolic, and oxidative responses. These data may help to guide athletes and coaches and contribute to public health recommendations on exercise and muscle damage particularly in the competitive periods.
authors.affiliation: 1 Research Laboratory "Sports Performance Optimization", National Center of Medicine and Science in Sports (CNMSS) , Tunis, Tunisia.|2 Faculty of Sciences of Bizerte, University of Carthage , Bizerte, Tunisia.
authors.forename: K
authors.initials: K
authors.lastname: Aloui
authors.affiliation: 3 Department of Physiology and Functional Explorations, Faculty of Medicine of Sousse, University of Sousse, Sousse, Tunisia.
authors.forename: S
authors.initials: S
authors.lastname: Abedelmalek
authors.affiliation: 1 Research Laboratory "Sports Performance Optimization", National Center of Medicine and Science in Sports (CNMSS) , Tunis, Tunisia.
authors.forename: H
authors.initials: H
authors.lastname: Chtourou
authors.affiliation: 4 Human Performance Laboratory, Technological and Higher Education Institute of Hong Kong , Hong Kong, China.
authors.forename: D P
authors.initials: DP
authors.lastname: Wong
authors.affiliation: 1 Research Laboratory "Sports Performance Optimization", National Center of Medicine and Science in Sports (CNMSS) , Tunis, Tunisia.
authors.forename: N
authors.initials: N
authors.lastname: Boussetta
authors.affiliation: 1 Research Laboratory "Sports Performance Optimization", National Center of Medicine and Science in Sports (CNMSS) , Tunis, Tunisia.
authors.forename: N
authors.initials: N
authors.lastname: Souissi
mesh_terms: D000704:Analysis of Variance; D015415:Biomarkers / Q000097:blood; D001794:Blood Pressure; D002940:Circadian Rhythm; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test / Q000379:methods*; D064368:Healthy Volunteers; D006339:Heart Rate; D006439:Hemodynamics; D000072696:High-Intensity Interval Training; D006801:Humans; D006854:Hydrocortisone / Q000097:blood*; D008315:Malondialdehyde / Q000097:blood; D009119:Muscle Contraction; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000378:metabolism*; D018384:Oxidative Stress; D010101:Oxygen Consumption; D010465:Perception; D011237:Predictive Value of Tests; D020127:Recovery of Function; D012420:Running; D013739:Testosterone / Q000097:blood*; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism; D013997:Time Factors; D055815:Young Adult
chemical_list: D015415:Biomarkers; D017392:Thiobarbituric Acid Reactive Substances; D013739:Testosterone; D008315:Malondialdehyde; D006854:Hydrocortisone
keywords: YYIRT; biochemical response; cardiovascular response; hormonal response; oxidative stress; time-of-day