Diurnal Variations of Plasma Homocysteine, Total Antioxidant Status, and Biological Markers of Muscle Injury During Repeated Sprint: Effect on Performance and Muscle Fatigue—A Pilot Study

Abstract

The aim of this study was (i) to evaluate whether homocysteine (Hcy), total antioxidant status (TAS), and biological markers of muscle injury would be affected by time of day (TOD) in football players and (ii) to establish a relationship between diurnal variation of these biomarkers and the daytime rhythm of power and muscle fatigue during repeated sprint ability (RSA) exercise. In counterbalanced order, 12 football (soccer) players performed an RSA test (5 x[6 s of maximal cycling sprint + 24 s of rest]) on two different occasions: 07:00-08:30 h and 17:00-18:30 h. Fasting blood samples were collected from a forearm vein before and 3-5 min after each RSA test. Core temperature, rating of perceived exertion, and performances (i.e., Sprint 1, Sprint 2, and power decrease) during the RSA test were significantly higher at 17:00 than 07:00 h (p < .001, p < .05, and p < .05, respectively). The results also showed significant diurnal variation of resting Hcy levels and all biological markers of muscle injury with acrophases (peak times) observed at 17:00 h. These fluctuations persisted after the RSA test. However, biomarkers of antioxidant status' resting levels (i.e., total antioxidant status, uric acid, and total bilirubin) were higher in the morning. This TOD effect was suppressed after exercise for TAS and uric acid. In conclusion, the present study confirms diurnal variation of Hcy, selected biological markers of cellular damage, and antioxidant status in young football players. Also, the higher performances and muscle fatigue showed in the evening during RSA exercise might be due to higher levels of biological markers of muscle injury and lower antioxidant status at this TOD.

Relationship between biomarkers of muscle damage and redox status in response to a weightlifting training session: effect of time-of-day

“…However, markers of muscle damage increased after the training sessions at 08:00 and 18:00 with a higher rate of increase in the morning for CK (59.9 ± 7.71% versus 29.89 ± 3.08%). These findings are partially in line with the previous studies of Yalcin et al (45) and Hammouda et al (16,17) who showed a significant …”

“…This confirms the results of the previous studies in which the authors found that the resting levels of WBC and biochemical markers of muscle damage were higher in the evening close to the acrophase of oral temperature (16)(17)(18)39). These results confirmed the suggestion that circadian changes in core temperature would increase the activity of enzymes, such as phosphofructokinase and LDH (12).…”

“…Immediately and 48 h after the training sessions, the present study showed that the diurnal variation persisted only for core temperature and WBC which is in line with the previous findings after the repeated sprint and Wingate exercise (16,17). However, the present findings showed the suppression of TOD effect in markers of muscle damage and antioxidant activities immediately and 48 h after weightlifting training sessions.…”

“…On the other hand, resting WBC, CK, and LDH have been shown to be affected by circadian rhythms in weightlifters (3) and soccer players (16) with acrophases generally observed at 17:00 close to the peak values of the oral temperature (36). In addition, a transient leukocytosis and increase in muscle damage have been reported after high-intensity exercise (e.g., repeated sprint and Wingate test) with higher post-exercise values observed at 17:00 compared to 07:00 (16)(17)(18). However, after a weightlifting training session, an alteration of the diurnal variation of WBC, CK, and LDH has been reported (3).…”

“…However, after a weightlifting training session, an alteration of the diurnal variation of WBC, CK, and LDH has been reported (3). Despite the important number of studies in this field, the exact mechanisms underlying these fluctuations are, yet, not well known (17,18).…”