Nizar Souissi

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.

The effect of training at a specific time of day: a review.

Abstract Chtourou, H and Souissi, N. The effect of training at a specific time of day: A review. J Strength Cond Res 26(7): 1984–2005, 2012—This article focuses on physical performances after training at a specific time of day. To date, although the effect of time of day on aerobic performances appears to be equivocal, during anaerobic exercises, the effect of time of day has been well established with early morning nadirs and peak performances in the late afternoon. These diurnal rhythms can be influenced by several factors such as the regular training at a specific time of day. Indeed, regular training in the morning hours may increase the lower morning performances to the same or even higher level as their normal diurnal peak typically observed in the late afternoon by a greater increase of performance in the evening. However, regular training in the evening hours may increase the morning-evening (i.e., amplitude of the rhythm) difference by a greater increase of performance in the late afternoon. Therefore, adaptations to training are greater at the time of day at which training is regularly performed than at other times. Nevertheless, although modifications in resting hormones concentrations could explain this time-of-day specific adaptations, precise information on the underlying mechanisms is lacking.

Effect of Time of Day and Partial Sleep Deprivation on Short‐Term, High‐Power Output

The purpose of this study was to determine whether delaying bedtime or advancing rising time by 4 h affects anaerobic performance of individuals the following day in the morning and afternoon. Eleven subjects participated in the study, during which we measured the maximal, peak, and mean powers (i.e., Pmax [force‐velocity test], Ppeak, and Pmean [Wingate test], respectively). Measurements were performed twice daily, at 07∶00 and 18∶00 h, following a reference normal sleep night (RN), a partial sleep deprivation timed at the beginning of the night (SDB), and a partial sleep deprivation timed at the end of the night (SDE), and oral temperature was measured every 4 h. Each of the three experimental conditions was separated by a one‐week period. Our results showed a circadian rhythm in oral temperature, and analysis of variance revealed a significant sleep×test‐time effect on peak power (Ppeak), mean power (Pmean), and maximal power (Pmax). These variables improved significantly from the morning to the afternoon for all three experimental conditions. Whereas the morning‐afternoon improvement in the measures was similar after the RN and SDB conditions, it was smaller following the SDE condition. There was no significant difference in the effect of the two sleep‐deprivation conditions on anaerobic performances at 07∶00 and at 18∶00 h under the SDB condition in comparison with the post‐reference night. However, the performance variables were significantly lower at 18∶00 h after the SDE condition. In conclusion, a 4 h partial sleep deprivation at the end of the night appears to be more disturbing than partial sleep deprivation at the beginning of the night.

THE EFFECT OF TRAINING AT THE SAME TIME OF DAY AND TAPERING PERIOD ON THE DIURNAL VARIATION OF SHORT EXERCISE PERFORMANCES

Chtourou, H, Chaouachi, A, Driss, T, Dogui, M, Behm, DG, Chamari, K, and Souissi, N. The effect of training at the same time of day and tapering period on the diurnal variation of short exercise performances. J Strength Cond Res 26(3): 697–708, 2012—The purpose of this investigation was to assess the effects of training and tapering at the same time of the day on the diurnal variations of short exercise performances. Thirty-one physically active men underwent 12 weeks of lower-extremity resistance training and 2 weeks of tapering. These subjects were matched and randomly assigned to a morning training group (MTG, training times 0700–0800 hours, n = 10), an evening training group (ETG, training times 1700–1800 hours, n = 11), and a control group (CG, completed all tests but did not train, n = 10). Muscular strength and power testing was conducted before (T0) and after 12 weeks of training (T1) and after 2 weeks of tapering (T2) in the morning (0700–0800 hours) and in the evening (1700–1800 hours). All morning and evening tests were performed in separate sessions (minimum interval = 36 hours) in a randomized design. In T0, the oral temperature and performances during the Wingate, vertical jump (squat jump and countermovement jump), and maximal voluntary contraction tests were higher in the evening than in the morning for all the groups. In T1, these diurnal variations were blunted in the MTG and persisted in the ETG and CG. In T2, the 2 weeks of tapering resulted in further time of day–specific adaptations and increases in short-term maximal performances. However, there was no significant difference in the relative increase between the MTG and the ETG after both training and tapering. From a practical point of view, if the time of competition is known, training and tapering sessions before a major competition must be conducted at the same time of the day at which ones critical performance is programmed. Moreover, if the time of the competition is not known, a tapering phase after resistance training program could be performed at any time of the day with the same benefit.

The effect of strength training at the same time of the day on the diurnal fluctuations of muscular anaerobic performances.

Chtourou, H, Driss, T, Souissi, S, Gam, A, Chaouachi, A, Souissi, N. The effect of strength training at the same time of the day on the diurnal fluctuations of muscular anaerobic performances. J Strength Cond Res 26(1): 217–225, 2012—The aim of this study was to examine the effects of training at the same time of the day on the diurnal variations of anaerobic performances to provide some recommendations to adjust training hours with the time of the day of competitive events. Thirty participants underwent 8 weeks of lower-extremity progressive resistance training performed 3 times per week designed to promote muscular strength and power. These subjects were randomly assigned to a morning training group (MTG, 07:00–08:00 hours, n = 10), an evening training group (ETG, 17:00–18:00 hours, n = 10), and a control group (CG, completed all tests but did not train, n = 10). Performance in the squat jump, the countermovement jump, the Wingate and 1 repetition maximum (1RM) during leg extension, leg curl, and squat tests was recorded just before and 2 weeks after an 8-week course of regular training. For all the subjects, the morning and evening tests were scheduled at the same time of the day as for the morning and evening training sessions. Before training, the results indicated a significant increase in performance from morning to evening tests (ca. 2.84–17.55% for all tests) for all groups. After training, the diurnal variations in anaerobic performances were blunted in the MTG. In fact, there was no significant difference in muscular power or strength between morning and evening tests. However, these intradaily variations in anaerobic performances persisted in the ETG and CG. From a practical point of view, adaptation to strength training is greater at the time of the day at which training was scheduled than at other times.

Effects of regular training at the same time of day on diurnal fluctuations in muscular performance

The aim of this study was to determine whether there is an effect of time of day on the adaptation to strength training at maximal effort. Fourteen participants took part in this experiment. Their peak anaerobic power (Wingate anaerobic test) and peak knee extension torque at six angular velocities (1.05, 2.10, 3.14, 4.19, 5.24 and 6.29 rad · s -1 ) were recorded in the morning (between 07:00 and 08:00 h) and in the evening (between 17:00 and 18:00 h) just before and 2 weeks after a 6 week course of regular training. Seven of them trained only in the morning and seven only in the evening. Multivariate analysis of variance revealed a significant group 2 pre-/post-training 2 time of day interaction effect for peak torque and peak anaerobic power. Before training, in both groups, peak torque and peak anaerobic power were significantly higher in the evening than in the morning. After training, there was no significant difference in peak torque and peak anaerobic power between the morning and the evening for the morning training group. In contrast, in the evening training group, peak torque and peak anaerobic power were higher in the evening than in the morning. As a result of training, both peak torque and peak anaerobic power increased from their initial values as expected. The morning training group improved their peak anaerobic power significantly in the morning and in the evening, the absolute increase being larger in the morning than in the evening. The evening training group did not improve their peak anaerobic power in the morning, whereas it improved significantly in the evening. Although peak torque was significantly improved by training in the morning and evening in both groups, the absolute increase was greater in the morning than in the evening in the morning training group, whereas the opposite was the case for the evening training group. These results suggest that training twice a week at a specific hour increases the peak torque and the peak anaerobic power specifically at this hour and demonstrates that there is a temporal specificity to strength training.

Diurnal Variation in Wingate-Test Performance and Associated Electromyographic Parameters

The present study was designed to evaluate time-of-day effects on electromyographic (EMG) activity changes during a short-term intense cycling exercise. In a randomized order, 22 male subjects were asked to perform a 30-s Wingate test against a constant braking load of 0.087 kg·kg−1 body mass during two experimental sessions, which were set up either at 07:00 or 17:00 h. During the test, peak power (Ppeak), mean power (Pmean), fatigue index (FI; % of decrease in power output throughout the 30 s), and evolution of power output (5-s span) throughout the exercise were analyzed. Surface EMG activity was recorded in both the vastus lateralis and vastus medialis muscles throughout the test and analyzed over a 5-s span. The root mean square (RMS) and mean power frequency (MPF) of EMG were calculated. Neuromuscular efficiency (NME) was estimated from the ratio of power to RMS. Resting core temperature, Ppeak, Pmean, and FI were significantly higher (p < .05) in the evening than morning test (e.g., Ppeak: 11.6 ± 0.8 vs. 11.9 ± 1 W·kg−1). The results showed that power output decreased following two phases. During the first phase (first 20s), power output decreased rapidly and values were higher (p < .05) in the evening than in the morning. During the second phase (last 10s), power decreased slightly and appeared independent of the time of day of testing. This power output decrease was paralleled by evolution of the MPF and NME. During the first phase, NME and MPF were higher (p < .05) in the evening. During the second phase, NME and MPF were independent of time of day. In addition, no significant differences were noticed between 7:00 and 17:00 h for EMG RMS during the whole 30 s. Taken together, these results suggest that peripheral mechanisms (i.e., muscle power and fatigue) are more likely the cause of the diurnal variation of the Wingate-test performance rather than central mechanisms. (Author correspondence: n_souissi@yahoo.fr)

Diurnal Variation in Wingate Test Performances: Influence of Active Warm-Up

The purpose of the present study was to examine the effects of active warm-up duration on the diurnal fluctuations in anaerobic performances. Twelve physical education students performed a medical stress test (progressive test up to exhaustion) and four Wingate tests (measurement of peak power [Ppeak], mean power [Pmean], and fatigue index during an all-out 30 s cycling exercise). The tests were performed in separate sessions (minimum interval = 36 h) in a balanced and randomized design at 08:00 and 18:00 h, either after a 5 min (5-AWU) or a 15 min active warm-up (15-AWU). AWU consisted of pedaling at 50% of the power output at the last stage of the stress exhausting test. Rectal temperature was collected throughout the sessions. A two-way ANOVA (warm-up × time of day) revealed a significant interaction for Ppeak (F(1.11) = 6.48, p < 0.05) and Pmean (F(1.11) = 5.84, p < 0.05): the time-of-day effect was significant (p < 0.001) in contrast with the effect of warm-up duration (p > 0.05). Ppeak and Pmean improved significantly from morning to afternoon after both 5-AWU and 15-AWU, but the effect of warm-up duration was significant in the morning only. Indeed, the values of Ppeak or Pmean were the same after both warm-up protocols in the afternoon. For rectal temperature, there was no interaction between time-of-day and warm-up duration. Rectal temperature before and after both the warm-up protocols was higher in the afternoon, and the effect of warm-up duration on temperature was similar at 08:00 and 18:00 h. In conclusion, the interpretation of the results of the anaerobic performance tests should take into account time-of-day and warm-up procedures. Longer warm-up protocols are recommended in the morning to minimize the diurnal fluctuations of anaerobic performances. (Author correspondence: n_souissi@yahoo.fr)

The effect of Ramadan fasting on the diurnal variations in aerobic and anaerobic performances in Tunisian youth soccer players

The purpose of this investigation was to assess the effects of Ramadan fasting on physical performance in youth Muslim athletes their diurnal fluctuations. In a balanced and randomized study design, 10 Tunisian junior male soccer players completed the Yo-Yo intermittent recovery test level 1 (YYIRT) and the repeated sprint ability (RSA) at 07:00 and 17:00 h on three different occasions: 1 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 two successive tests. Oral temperature was measured before each test. Under each condition, the results showed a time-of-day effect on oral temperature. However, no significant diurnal variations in rate of perceived exertion (RPE) scores were observed during the three periods (BR, SWR and ER). Performances during the YYIRT and the first two sprints of the RSA improved significantly from morning to evening during BR. However, daily fluctuations disappeared during the SWR and ER. Considering the effect of Ramadan on physical performances, in comparison with BR, no significant difference was observed during Ramadan at 07:00 h. However, the variables were significantly lower in SWR and ER at 17:00 h. The RPE scores were higher during SWR and ER in the evening after the YYIRT and RSA tests. In conclusion, the time-of-day effects on physical performances variables tend to disappear during Ramadan. In comparison with the period BR, physical performances were unaffected at 07:00 h but impaired at 17:00 h during Ramadan.

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.