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Souissi M.,University of Sfax | Chtourou H.,Research Laboratory Sport Performance Optimization | Chtourou H.,University of Sfax | Abedelmalek S.,University of Sousse | And 2 more authors.
Physiology and Behavior | Year: 2014

The aim of the present study was to investigate the effects of caffeine ingestion on cognitive and physical performances after 36h of sleep deprivation. In randomized order, thirteen healthy male physical education students (age: 21.1±1.1years, body mass: 77.1±7.2kg, height: 1.77±0.06m) completed four test sessions at 18:00h: after placebo or 5mg·kg-1 of caffeine ingestion during a baseline night (RN) (bed time: from 22:30h to 07:00h) or a night of 36h of sleep deprivation (TSD). During each test session, participants performed the squat jump (SJ), the reaction time, and the 30-s Wingate tests (i.e., for the measurement of the peak (PP) and mean (MP) powers and the fatigue index (FI)). The results showed that PP and MP decreased and FI increased during the TSD compared to RN in the placebo condition (p<0.001). The caffeine ingestion improved PP after TSD compared to RN (p<0.001). SJ decreased significantly after the TSD compared to RN after both placebo and caffeine ingestions (p<0.001). However, SJ increased significantly after caffeine ingestion during RN and TSD (p<0.001). The reaction time increased significantly after TSD compared to RN (p<0.001). However, the reaction time decreased significantly after the caffeine ingestion only during the TSD (p<0.001). Therefore, caffeine is an effective strategy to counteract the effect of 36h of sleep loss on physical and cognitive performances. © 2014.


Racil G.,Tunis el Manar University | Ben Ounis O.,Manouba University | Hammouda O.,Manouba University | Hammouda O.,Research Laboratory Sport Performance Optimization | And 5 more authors.
European Journal of Applied Physiology | Year: 2013

Purpose: We investigate the effects of 12-week interval training of moderate- or high-intensity exercise on blood lipids and plasma levels of adiponectin. Methods: Thirty-four obese adolescent females [age = 15.9 ± 0.3 years; BMI and BMI-Z-score = 30.8 ± 1.6 kg/m2 and 3 ± 0.3, respectively], were randomized to high-intensity interval training (HIIT, n = 11), moderate-intensity interval training (MIIT, n = 11), or a control group (CG, n = 12). Maximal oxygen uptake (VO2peak, maximal aerobic speed (MAS), plasma lipids and adiponectin levels were measured in all subjects before and after training. Results: Following the training program, in both training groups, body mass, BMI-Z-score, and percentage body fat (% BF) decreased, while VO2peak and MAS increased. Low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and adiponectin levels were positively altered (-12.6 and -7.4 %; 6.3 and 8.0 %; 35.8 and 16.2 %; high to moderate training program, respectively). Waist circumference, triglyceride and total cholesterol decreased only in HIIT group (-3.5; -5.3 and -7.0 %, respectively, in all P < 0.05). Significant decrease in the usual index of insulin resistance (HOMA-IR) occurred in HIIT and MIIT groups (-29.2 ± 5.3 and -18.4 ± 8.6 %, respectively; P < 0.01). Conclusion: The results show that HIIT positively changes blood lipids and adiponectin variables in obese adolescent girls, resulting in improved insulin sensitivity, as attested by a lower HOMA-IR, and achieving better results compared to moderate-intensity exercise. © 2013 Springer-Verlag Berlin Heidelberg.


Rebai H.,University of Sousse | Rebai H.,University of Sfax | Chtourou H.,University of Sfax | Chtourou H.,Research Laboratory Sport Performance Optimization | And 7 more authors.
International Journal of Sports Medicine | Year: 2014

We aimed to examine the effect of maintaining or reducing resistance training volume during Ramadan-intermittent-fasting (RIF) on short-term maximal performances. 20 footballers (age: 18.4±0.8 years; body-mass: 72.4±4.1 kg; height: 183.4±4.6 cm) were matched and randomly assigned to a normal-training-group (G1) or a tapering-group (G2). They were tested for muscular strength (maximal-voluntary-contraction) and power (squat-jump and counter-movement-jump) 1 month before RIF (T0), 1 week before RIF (T1), after 2 weeks of fasting (T2) and at the end of RIF (T3). From T1 to T2, subjects performed a whole-body resistance training program (8-repetitions×4-sets with 4-min recovery in-between). During RIF, G1 maintained the same training program, while G2 performed a period of reduced training volume (3 sets/exercise; - 22%). Muscle strength and power increased significantly from T0 to T1, from T0 to T2 and from T0 to T3 in G1 and G2 and from T1 to T2 and from T1 to T3 only in G2 (p<0.05). Performance was higher in G2 than G1 during T2 (p<0.01). Moreover, the Δ-change of performance between T0 and T2 and T3 was significantly higher in G2 than G1 (p<0.05). For young soccer players, a tapering period characterized by a reduced training volume during RIF may lead to significant improvement in muscle strength and power. © Georg Thieme Verlag KG Stuttgart · New York.


Aloui A.,University of Sfax | Chaouachi A.,Research Laboratory Sport Performance Optimization | Chtourou H.,Research Laboratory Sport Performance Optimization | Wong D.P.,The Hong Kong Institute of Education | And 3 more authors.
International Journal of Sports Physiology and Performance | Year: 2013

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 MVC pre 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. © 2013 Human Kinetics, Inc.


Baklouti H.,Research Laboratory Sport Performance Optimization | Aloui A.,Research Laboratory Sport Performance Optimization | Aloui A.,Gafsa University | Chtourou H.,Research Laboratory Sport Performance Optimization | And 4 more authors.
PLoS ONE | Year: 2015

Aim: The purpose of this study was to examine the effect of active warm-up duration on shortterm maximal performance assessed during Ramadan in the afternoon. Methods: Twelve healthy active men took part in the study. The experimental design consisted of four test sessions conducted at 5 p.m., before and during Ramadan, either with a 5-minute or a 15-minute warm-up. The warm-up consisted in pedaling at 50% of the power output obtained at the last stage of a submaximal multistage cycling test. During each session, the subjects performed two vertical jump tests (squat jump and counter movement jump) for measurement of vertical jump height followed by a 30-second Wingate test for measurement of peak and mean power. Oral temperature was recorded at rest and after warmingup. Moreover, ratings of perceived exertion were obtained immediately after the Wingate test. Results: Oral temperature was higher before Ramadan than during Ramadan at rest, and was higher after the 15-minute warm-up than the 5-minute warm-up both before and during Ramadan. In addition, vertical jump heights were not significantly different between the two warm-up conditions before and during Ramadan, and were lower during Ramadan than before Ramadan after both warm-up conditions. Peak and mean power were not significantly different between the two warm-up durations before Ramadan, but were significantly higher after the 5-minute warm-up than the 15-minute warm-up during Ramadan. Moreover, peak and mean power were lower during Ramadan than before Ramadan after both warm-up conditions. Furthermore, ratings of perceived exertion were higher after the 15-minute warm-up than the 5-minute warm-up only during Ramadan. Conclusion: The prolonged active warm-up has no effect on vertical jump height but impairs anaerobic power assessed during Ramadan in the afternoon. © 2015 Baklouti et al.

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