Omar Hammouda

The Effect of Time-of-Day and Ramadan Fasting on Anaerobic Performances

This study was designed to assess the effects of Ramadan-intermittent-fasting (RIF) and time-of-day on muscle power and fatigue during the Wingate test. In a randomized design, 10 football players completed a Wingate test at 07:00 and 17:00 h on 3 different occasions: one week before Ramadan (BR), the second week of Ramadan (SWR) and the fourth week of Ramadan (ER). There was an interval of 36-h between any 2 successive tests. During the Wingate test, peak power (PP), mean power (MP) and the fatigue index (FI) were recorded. While PP, MP and FI were greater in the evening than in the morning during BR (p<0.001), these diurnal variations in muscle power disappeared during the month of Ramadan (i. e., SWR and ER) due to a significant decrease in PP and MP in the evening (p<0.001). However, the diurnal variation in FI when measured at 17:00 h increased during this month (p<0.001). In addition, ratings of perceived exertion and fatigue were higher in the evening during Ramadan in comparison with BR. These results suggest that Ramadan might modify the circadian rhythm of muscle power and fatigue during the Wingate test by decreasing power output and increasing muscle fatigue at the time of the acrophase.

Changes in Oxidative Stress Markers and Biological Markers of Muscle Injury with Aging at Rest and in Response to an Exhaustive Exercise

Purpose The aim of this study was to evaluate whether oxidative stress markers and biomarkers of muscle injury would be affected by aging at rest and in response to an incremental exhaustive exercise. Methods Fifteen young (20.3±2.8 years) and fifteen older adults (65.1±3.5 years) performed an incremental cycle ergometer test to exhaustion. Before and after exercise, oxidative stress [superoxide dismutase (SOD), glutathione peroxidase (GPX), glutathione reductase (GR), ascorbic acid, α-Tocopherol, malondialdehyde (MDA)] and muscle injury [creatine kinase (CK), lactate deshydrogenase (LDH)] biomarkers were assessed. Results At rest, there was no difference in oxidative stress markers and LDH level between the groups, however CK was significantly higher in the young group than the elderly group (p<0.05). During recovery, in comparison with resting values, a significant increase in SOD (1092±145.9 vs. 1243±98 U/g Hb), GPX (67.4±12.7 vs. 79.2±15.6 U/g Hb) and GR (6.5±0.9 vs. 7.7±0.5 U/g Hb) activities were observed only in the young group (p<0.05). MDA has increased only in the older group (0.54±0.2 vs. 0.79±0.2 µmol/l) (p<0.01). CK increased in both groups (young group: 122.5±22.2 vs. 161.9±18.7 UI/l; older group: 88.8±34.1 vs. 111.1±25.9 UI/l) (p<0.01), however LDH has increased only in the young group (400.5±22.2 vs. 485±18.7 UI/l) (p<0.01) without alteration in the older group (382.8±34.1 vs. 418.5±25.9 UI/l). Conclusions These findings indicate that aging is associated with a decrease in antioxidant efficiency and an increase in oxidative stress damage. Furthermore, older adults would not more susceptible to exercise-induced muscle injury than young people.

High intensity exercise affects diurnal variation of some biological markers in trained subjects.

The study investigated if markers of muscle injury and antioxidant status were affected by a Wingate test performed at 2 different times of day. 15 young male footballers performed 2 tests (randomized) at 07:00-h and 17:00-h. Fasting blood samples were collected before and 3 min after each test for assessment of markers of muscle injury and antioxidant status. Resting oral temperature was recorded during each session. Peak power (10.76 ± 1.05 vs. 11.15 ± 0.83 W.kg( - 1)) and fatigue index (0.41 ± 0.04 vs. 0.49 ± 0.13%) during the Wingate test, and core temperature, were significantly higher (all p<0.05) in the evening. Markers of muscle injury were significantly higher in the evening before and after exercise (e. g., 148.7 ± 67.05 vs. 195 ± 74.6 and 191.6 ± 79.52 vs. 263.6 ± 96.06 IU.L (- 1), respectively, for creatine kinase; both p<0.001). Antioxidant parameters increased after the Wingate test but only resting values were significantly higher in the morning (e. g., 1.33 ± 0.19 vs. 1.19 ± 0.14 µmol.L (- 1) for total antioxidant status; p<0.05). The results indicate that muscle injury and antioxidant activity after the Wingate test were higher in the evening, suggesting a possible link between the biochemical measures and the diurnal fluctuation of anaerobic performance. However, repetition of this study after prescribed rather than self-selected exercise intensity is recommended.

Effects of Time-of-day and Partial Sleep Deprivation on Short-term Maximal Performances of Judo Competitors

Abstract Souissi, N, Chtourou, H, Aloui, A, Hammouda, O, Dogui, M, Chaouachi, A, and Chamari, K. Effects of time-of-day and partial sleep deprivation on short-term maximal performances of judo competitors. J Strength Cond Res 27(9): 2473–2480, 2013—This study assessed the effects of partial sleep deprivation on short-term maximal performances of judokas in the morning and afternoon of the following day. In a randomized design, 12 judokas completed the maximal voluntary contraction, the handgrip, and the Wingate tests before and after a judo combat. Measurements were performed at 09:00 and 16:00 hours after a reference-normal sleep night and 2 conditions of 4-hour partial sleep deprivation timed at the beginning (SDB) or at the end of the night (SDE). The results showed that muscle power and strength were significantly higher at 16:00 than 09:00 hours (p < 0.05). These diurnal variations disappeared after SDB and SDE and after the combat. In addition, SDE resulted in significant decreases of short-term maximal performance in the afternoon (p < 0.01). In conclusion, SDE decreased muscle strength and power at 16:00 hours and, therefore, might have blunted the diurnal variations of short-term maximal exercise. Thus, early rising is more detrimental than late bedtime to muscle strength and power for judo athletes when competitions are scheduled in the afternoon hours.

Time of Day Effects on Repeated Sprint Ability

The present study aimed at investigating the effects of time-of-day on muscle power and associated electromyographic (EMG) activity level of 4 thigh muscles during a repeated pedalling sprint exercise. After a familiarization session, 12 male subjects were asked to perform the repeated sprint ability test during 2 experimental sessions (randomized order), which were set up either at 06:00 or 18:00 h. For each sprint, peak power output, percentage of peak power decrement and total work were calculated. EMG activity of vastus lateralis, rectus femoris, vastus medialis and biceps femoris muscles was recorded throughout the test and analyzed for each sprint. Total work and percentage of peak power decrement were higher in the evening than in the morning (p<0.01 and p<0.05, respectively). Likewise, peak power was significantly higher at 18:00 than 06:00 h during the first 3 sprints (p<0.01 for sprint 1 and p<0.05 for sprint 2 and 3). There was no time-of-day effect for EMG activity level. The neuromuscular efficiency decreased significantly over the repeated sprint ability test at the 2 times of testing (p<0.01). Despite diurnal fluctuation in muscular power and neuromuscular fatigue during the repeated sprint ability test, EMG activity of major thigh muscles was not time-of-day dependent.

Morning-to-evening difference of biomarkers of muscle injury and antioxidant status in young trained soccer players

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 well-trained soccer players. In a counterbalanced order, 20 soccer players participated on two different occasions between 07:00 and 08:30 h and between 17:00 and 18:30 h. Fasting blood samples were collected from a forearm vein during each session. The results showed that the values of white blood cells (WBC), neutrophils (NE), lymphocytes (LY), and monocytes (MO) are higher in the evening than the morning. Although there was no TOD effect on blood lactate (Lac) levels, significant difference was observed for urea (URE), creatinine (CRE), and blood glucose (GLC) indicating higher evening levels. Moreover, the results also showed diurnal variations of core temperature, resting Hcy levels, and all biological markers of muscle injury [i.e., aspartate aminotransferase (ASAT), creatine kinase (CK), lactate dehydrogenase (LDH)].These parameters were lowest in the morning and tended to rise throughout the day. Furthermore, biomarkers of antioxidant status [i.e., TAS, uric acid (UA), and total bilirubin (TBIL)] displayed a significant effect of TOD with higher morning levels. In conclusion, the present study confirms the diurnal variations of Hcy, selected biological markers of cellular damage, and antioxidant status in young trained soccer players. Our finding suggests the fact that muscle damage and inflammation could be more important in the evening and that antioxidant status is more efficient in the morning.

Time-of-day effects on biochemical responses to soccer-specific endurance in elite Tunisian football players

Abstract This study aimed to investigate footballers’ diurnal variation of performance during the Yo-Yo intermittent recovery test and the associated biochemical responses. Fifteen male footballers (17.3 ± 0.3 years, 69.1 ± 4.2 kg, 179.7 ± 3.6 cm) performed two randomised Yo-Yo tests at 07:00 h and 17:00 h. Blood samples were collected before and 3 min after each test for the assessment of metabolic responses. Resting oral temperature and rating of perceived exertion (RPE) after and peak heart rate during the Yo-Yo test were recorded at both times-of-day. Core temperature and performances during the Yo-Yo test increased from the morning to the evening (P < 0.0005 and P = 0.01, respectively) without significant time-of-day effects on peak heart rate and RPE. Moreover, pre- and post-Yo-Yo test biochemical parameters (high-density lipoprotein, triglycerides, glucose, creatine-kinase) were higher at 17:00 h than 07:00 h (160.45 ± 18.68 vs. 173.73 ± 14.48 before and 191.18 ± 21.13 vs. 219.27 ± 27.74 IU · L−1 after the Yo-Yo test at 07:00 h and 17:00 h, P = 0.032 and P < 0.0005, respectively for creatine-kinase). Only post-exercise lactate levels were higher in the evening (9.82 ± 0.65 vs. 10.86 ± 0.33 mmol · L−1, P < 0.0005) with all biochemical variables being increased after the exercise (P < 0.0005). These findings suggest a possible link between the diurnal fluctuation of metabolic responses and the related pattern of specific-endurance performances in footballers. Therefore, the higher biochemical responses observed in the evening could explain, partially, the greater performance and metabolic solicitation at this time-of-day.

Effects of partial sleep deprivation at the end of the night on anaerobic performances in judokas

The aim of the present study was to examine the effect of partial sleep deprivation at the end of the night (PSDE) on anaerobic performances during the Wingate test (peak (PP) and mean (MP) power) and the hand grip (HG) test in judokas. In a randomized order, twenty-one judokas (age: 19.1 ± 1.2 yrs; height: 176.5 ± 4.2 cm; body mass: 77.3 ± 6.3 kg) performed two sessions after a normal sleep night (NSN) or a PSDE. During each session, they carried out the Wingate and the HG tests before (T0) and after (T1) a judo match. Rating of perceived exertion (RPE) scores were obtained at the end of the combat. PP and MP decreased significantly from T0 to T1 during the two experimental conditions (p < 0.01), and from NSN to PSDE at T0 and T1 (p < 0.05). However, the HG strength decreased only from T0 to T1 (p < 0.001) and was not significantly affected by PSDE. Likewise, the RPE scores were not affected by PSDE. Therefore, PSDE (i) reduced muscle power during the Wingate test and (ii) did not affect muscle strength during the HG test.

Effect of Static and Dynamic Stretching on the Diurnal Variations of Jump Performance in Soccer Players

Purpose The present study addressed the lack of data on the effect of different types of stretching on diurnal variations in vertical jump height - i.e., squat-jump (SJ) and countermovement-jump (CMJ). We hypothesized that dynamic stretching could affect the diurnal variations of jump height by producing a greater increase in short-term maximal performance in the morning than the evening through increasing core temperature at this time-of-day. Methods Twenty male soccer players (age, 18.6±1.3 yrs; height, 174.6±3.8 cm; body-mass, 71.1±8.6 kg; mean ± SD) completed the SJ and CMJ tests either after static stretching, dynamic stretching or no-stretching protocols at two times of day, 07:00 h and 17:00 h, with a minimum of 48 hours between testing sessions. One minute after warming-up for 5 minutes by light jogging and performing one of the three stretching protocols (i.e., static stretching, dynamic stretching or no-stretching) for 8 minutes, each subject completed the SJ and CMJ tests. Jumping heights were recorded and analyzed using a two-way analysis of variance with repeated measures (3 [stretching]×2 [time-of-day]). Results The SJ and CMJ heights were significantly higher at 17:00 than 07:00 h (p<0.01) after the no-stretching protocol. These daily variations disappeared (i.e., the diurnal gain decreased from 4.2±2.81% (p<0.01) to 1.81±4.39% (not-significant) for SJ and from 3.99±3.43% (p<0.01) to 1.51±3.83% (not-significant) for CMJ) after dynamic stretching due to greater increases in SJ and CMJ heights in the morning than the evening (8.4±6.36% vs. 4.4±2.64%, p<0.05 for SJ and 10.61±5.49% vs. 6.03±3.14%, p<0.05 for CMJ). However, no significant effect of static stretching on the diurnal variations of SJ and CMJ heights was observed. Conclusion Dynamic stretching affects the typical diurnal variations of SJ and CMJ and helps to counteract the lower morning values in vertical jump height.

The effect of time-of-day and judo match on short-term maximal performances in judokas

The aim of the present study was to investigate the time-of-day effect on short-term maximal performances before and after a judo match in young judokas. Ten male judokas (age, 18.2 ± 1.4 yrs; height, 176.5 ± 4.6 cm; body mass, 74.1 ± 9.6 kg) performed three test sessions at 09:00, 12:30, and 16:00 h. During each session, they completed the hand grip (HG) and the Wingate tests before (T0) and after (T1) a 5-min judo combat. Likewise, core temperature was measured at T0 and T1 in all sessions. Rating of perceived exertion (RPE) scores were obtained at the end of each combat. Core temperature recorded before and after the judo match was lower at 09:00 h than 12:30 h and 16:00 h, and at 12:30 h than 16:00 h (p < 0.001). Furthermore, the results indicated a significant increase in core temperature after the combat with respect to before the combat at the three times of measurement (p < 0.001). Muscle strength and power were significantly lower at 09:00 h than 16:00 h only before the combat (p < 0.05). Furthermore, the results indicated a significant decrease in muscle strength and power at 09:00, 12:30, and 16:00 h after the combat than before the combat (p < 0.05), with higher decrease in performance at 16:00 h than 09:00 and 12:30 h (e.g. 3.7 ± 6.2% vs. 3.7 ± 1.7% vs. 6.4 ± 5.0% for HG at 09:00, 12:30, and 16:00 h, respectively). The RPE scores were not significantly different between 09:00, 12:30, and 16:00 h. In conclusion, judokas’ muscle power and strength were significantly higher in the afternoon than the morning. However, these diurnal variations disappeared after the judo match by a higher fatigue in the afternoon than the morning.