Search Results

You are looking at 1 - 3 of 3 items for

  • Author: Hamdi Chtourou x
Clear All Modify Search
Restricted access

Asma Aloui, Anis Chaouachi, Hamdi Chtourou, Del P. Wong, Monoem Haddad, Karim Chamari and Nizar Souissi

Purpose:

This study examined the effects of Ramadan on cycling repeated-sprint ability (RSA) and corresponding diurnal variations.

Methods:

Twelve active men performed an RSA test (5 × 6-s maximal sprints interspersed with 24 s passive recovery) during morning and afternoon sessions 1 wk before Ramadan (BR), during the second (R2) and the fourth (R4) weeks of Ramadan, and 2 wk after Ramadan (AR). Maximal voluntary contraction was assessed before (MVCpre), immediately after (MVCpost), and 5 min after the RSA test (MVCpost5). Moreover, hematocrit, hemoglobin, and plasma sodium and potassium (K+) concentrations were measured at rest and after the RSA test and MVCpost.

Results:

Overall, peak power (Ppeak) during the RSA test decreased throughout the 5 sprints. Ppeak measured in the first sprint and MVCpre were lower during Ramadan than BR in the afternoon (P < .05) and higher in the afternoon than the morning BR and AR (P < .05). However, this diurnal rhythmicity was not found for the last 4 sprints’ Ppeak, MVCpost, and MVCpost5 in all testing periods. Furthermore, the last 4 sprints’ Ppeak, MVCpost, MVCpost5, and morning MVCpre were not affected by Ramadan. [K+] measured at rest and after the RSA test and MVCpost were higher during Ramadan than BR in the afternoon (P < .05) and higher in the afternoon than the morning during Ramadan (P < .05).

Conclusions:

Fatigability is higher in the afternoon during Ramadan, and, therefore, training and competition should be scheduled at the time of day when physical performance is less affected.

Restricted access

Hichem Souissi, Hamdi Chtourou, Anis Chaouachi, Mohamed Dogui, Karim Chamari, Nizar Souissi and Mohamed Amri

The aim of this study was to assess the effect of time-of-day-specific training on the diurnal variations of short-term performances in boys. Twenty-four boys were randomized into a morning-training-group (07:00–08:00h; MTG), an evening training-group (17:00–18:00h; ETG) and a control-group (CG). They performed four tests of strength and power (unilateral isometric maximal voluntary contraction of the knee extensor muscles, Squat-Jump, Counter-Movement-Jump and Wingate tests) at 07:00 and 17:00h just before (T0) and after 6 weeks of resistance training (T1). In T0, the results revealed that short-term performances improved and oral temperature increased significantly from morning to afternoon (amplitudes between 2.36 and 17.5% for both oral temperature and performances) for all subjects. In T1, the diurnal variations of performances were blunted in the MTG and persisted in the ETG and CG. Moreover, the training program increase muscle strength and power especially after training in the morning hours and the magnitude of gains was greater at the time-of-day-specific training than at other times. In conclusion, these results suggest that time-of-day-specific training increases the child’s anaerobic performances specifically at this time-of-day. Moreover, the improvement of these performances was greater after morning than evening training.

Restricted access

Achraf Ammar, Stephen J. Bailey, Omar Hammouda, Khaled Trabelsi, Nabil Merzigui, Kais El Abed, Tarak Driss, Anita Hökelmann, Fatma Ayadi, Hamdi Chtourou, Adnen Gharbi and Mouna Turki

Purpose: The effect of playing surface on physical performance during a repeated-sprint ability (RSA) test and the mechanisms for any potential playing-surface-dependent effects on RSA performance are equivocal. The purpose of this study was to investigate the effect of natural grass (NG) and artificial turf (AT) on physical performance, ratings of perceived exertion, feeling scale, and blood biomarkers related to anaerobic contribution (blood lactate [Lac]), muscle damage (creatine kinase and lactate dehydrogenase), inflammation (C-reactive protein), and immune function (neutrophils [NEU], lymphocytes [LYM], and monocytes) in response to an RSA test. Methods: A total of 9 male professional football players from the same regional team completed 2 sessions of RSA testing (6 × 30 s interspersed with a 35-s recovery) on NG and AT in a randomized order. During the RSA test, total (sum of distances) and peak (highest distance covered in a single repetition) distance covered were determined using a measuring tape, and the decrement in sprinting performance from the first to the last repetition was calculated. Before and after the RSA test, ratings of perceived exertion, feeling scale, and Lac, creatine kinase, lactate dehydrogenase, C-reactive protein, NEU, LYM, and monocytes were recorded in both NG and AT conditions. Results: Although physical performance declined during the RSA blocks on both surfaces (P = .001), the distance covered declined more on NG (15%) than on AT (11%; P = .04; effect size [ES] = −0.34; 95% confidence interval [CI], −1.21 to 0.56) with a higher total distance covered (+6% [2%]) on AT (P = .018; ES = 1.15; 95% CI, 0.16 to 2.04). In addition, lower ratings of perceived exertion (P = .04; ES = −0.49; 95% CI, −1.36 to 0.42), Lac, NEU, and LYM (P = .03; ES = −0.80; 95% CI, −1.67 to 0.14; ES = −0.16; 95% CI, −1.03 to 0.72; and ES = −0.94; 95% CI, −1.82 to 0.02, respectively) and more positive feelings (P = .02; ES = 0.81; 95% CI, −0.13 to 1.69) were observed after the RSA test performed on AT than on NG. No differences were observed in the remaining physical and blood markers. Conclusion: These findings suggest that RSA performance is enhanced on AT compared with NG. This effect was accompanied by lower fatigue perception and Lac, NEU, and LYM and a more pleasurable feeling. These observations might have implications for physical performance in intermittent team-sport athletes who train and compete on different playing surfaces.