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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.


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.


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.


Hammouda O.,Research Laboratory Sport Performance Optimization | Hammouda O.,University of Sfax | Chtourou H.,Research Laboratory Sport Performance Optimization | Chahed H.,Biochemistry Laboratory | And 6 more authors.
Chronobiology International | Year: 2011

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×[6 s of maximal cycling sprint+24 s of rest]) on two different occasions: 07:0008:30h and 17:0018:30h. Fasting blood samples were collected from a forearm vein before and 35min 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 07:00h (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 17:00h. 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. © Informa Healthcare USA, Inc.


Hajsalem M.,University of Sfax | Chtourou H.,Research Laboratory Sport Performance Optimization | Aloui A.,Research Laboratory Sport Performance Optimization | Hammouda O.,Research Laboratory Sport Performance Optimization | And 2 more authors.
Biological Rhythm Research | Year: 2013

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. © 2013 Copyright Taylor and Francis Group, LLC.


PubMed | Research Laboratory Sport Performance Optimization, University of Sfax, University of Monastir, University of Sousse and Paris West University Nanterre La Défense
Type: | Journal: Journal of the International Society of Sports Nutrition | Year: 2016

The present study aimed to investigate the concomitant effects of Ramadan intermittent fast (RIF) and muscle fatigue on neuromuscular performances and reaction times in young trained athletes.Eight karate players (17.20.5years) were tested on three sessions: during a control period (S1: one week before Ramadan), and during the first (S2) and the fourth week of RIF (S3). Dietary intake and anthropometric measurements were assessed before each session. During each test session, participants performed maximal voluntary isometric contractions (MVC) and a submaximal contraction at 75% MVC until exhaustion (T lim ) of the right elbow flexors. Surface electromyography was recorded from biceps brachii muscle during MVC and T lim . Simple (SRT) and choice (CRT) reaction times were evaluated at rest and just after T lim in a random order.The total daily energy (S2: +19.5%, p<0.05; S3: +27.4%, p<0.01) and water (S2: +26.8%, p<0.01; S3: +23.2%, p<0.05) intake were significantly increased during RIF. However, neither body mass nor body mass index was altered by RIF (F (2,14)=0.80, p=0.47 and F (2,14)=0.78, p=0.48, respectively). In addition, T lim (F (2,14)=2.53, p=0.12), MVC (F (2,14)=0.51, p=0.61) and associated electrical activity (F (2,14)=0.13, p=0.88) as well as neuromuscular efficiency (F (2,14)=0.27, p=0.76) were maintained during RIF. Moreover, neither SRT nor CRT was affected by RIF (F (2,14)=1.82, p=0.19 and F (2,14)=0.26, p=0.78, respectively) or neuromuscular fatigue (F (1,7)=0.0002, p=0.98 and F (1,7)=3.78, p=0.09, respectively).The present results showed that RIF did not adversely affect the neuromuscular performances and anthropometric parameters of elite karate athletes who were undertaking their usual training schedule. In addition, neither RIF nor neuromuscular fatigue poorly affects reaction times in elite karate athletes.


PubMed | Tunis el Manar University, University of Rouen, Qatar University, Research Laboratory Sport Performance Optimization and 2 more.
Type: Journal Article | Journal: Biology of sport | Year: 2016

This study examined the effects of high- vs. moderate-intensity interval training on cardiovascular fitness, leptin levels and ratings of perceived exertion (RPE) in obese female adolescents. Forty-seven participants were randomly assigned to one of three groups receiving either a 1:1 ratio of 15 s of effort comprising moderate-intensity interval training (MIIT at 80% maximal aerobic speed: MAS) or high-intensity interval training (HIIT at 100% MAS), with matched 15 s recovery at 50% MAS, thrice weekly, or a no-training control group. The HIIT and MIIT groups showed improved (p < 0.05) body mass (BM), BMI Z-score, and percentage of body fat (%BF). Only the HIIT group showed decreased waist circumference (WC) (p = 0.017). The effect of exercise on maximal oxygen uptake (VO2max) was significant (p = 0.019, ES = 0.48 and p = 0.010, ES = 0.57, HIIT and MIIT, respectively). The decrease of rate-pressure product (RPP) (p < 0.05, ES = 0.53 and ES = 0.46, HIIT and MIIT, respectively) followed the positive changes in resting heart rate and blood pressures. Blood glucose, insulin level and the homeostasis model assessment index for insulin decreased (p < 0.05) in both training groups. Significant decreases occurred in blood leptin (p = 0.021, ES = 0.67 and p = 0.011, ES = 0.73) and in RPE (p = 0.001, ES = 0.76 and p = 0.017, ES = 0.57) in HIIT and MIIT, respectively. In the post-intervention period, blood leptin was strongly associated with %BF (p < 0.001) and VO2max (p < 0.01) in the HIIT and MIIT groups, respectively, while RPE was strongly associated with BM (p < 0.01) in the HIIT group. The results suggest that high-intensity interval training may produce more positive effects on health determinants in comparison with the same training mode at a moderate intensity.


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.


PubMed | University of Toronto, Research Laboratory Sport Performance Optimization, University of Carthage, Laboratory of Physiology and Qatar Orthopaedic and Sports Medicine Hospital
Type: Journal Article | Journal: Biology of sport | Year: 2016

Recreational soccer (RS) is becoming a popular alternative to the classical continuous exercise mode used for the improvement of cardiovascular and metabolic fitness in untrained people. The objective of this paper was to conduct a detailed systematic review of the literature, identifying the physiological responses to RS and the training effects of RS on aerobic fitness and health in untrained healthy individuals and clinical patients. PubMed, Google Scholar and ScienceDirect databases were searched using terms related to recreational soccer. Inclusion criteria were randomized controlled trials (RCT) that assessed acute physiological responses to RS or the training effects of RS on physical fitness and health in sedentary, untrained subjects of any age or health status. All studies were assessed for methodological quality using the PEDro scale. Thirty-five articles met the inclusion criteria; seven examined the acute response to RS, and 28 assessed training effects. Clear evidence was found that RS had positive effects on many health-related indices and variables, including VO2max (gains of 7-16%), blood pressure (reductions of 6-13 mmHg), body composition (decreased fat mass and improved indices of bone health), and metabolic and cardiac function. These positive effects were observed in both healthy individuals and clinical patients, irrespective of age or sex. Although this review provides clear evidence of the positive effects of RS on health, most studies had limitations of methodology (an average PEDro score < 6). Furthermore, many of the training studies were from a small number of research groups. Future studies should be extended to other countries and institutions to ensure generality of the results. Regular RS training leads to significant cardiovascular and muscular adaptations and gains of health both in sedentary individuals and clinical patients at all ages, suggesting that RS is a potentially highly motivational method to enhance population health.


PubMed | Research Laboratory Sport Performance Optimization
Type: | Journal: The Journal of sports medicine and physical fitness | Year: 2016

To evaluate the effect of two types of partial sleep deprivation (PSD) on biomarkers of muscle and cardiac injuries in response to acute intermittent exercise in professional athletes.In a counterbalanced order, Ten healthy male Taekwondo athletes were asked to perform the Yo-Yo Intermittent Recovery Test (YYIRT) in three conditions, allowing a 36 h recovery period in between: i) following a full night of habitual sleep known as a reference sleep night (RN); ii) following PSD in the beginning of the night (PSDBN), and iii) following PSD in the end of the night (PSDEN). Heart rate (HR) and arterial oxygen saturation (SaO2) were measured during exercise. Blood samples were taken just before and 3 min after the YYIRT to measure biomarkers related to muscle and cardiac injuries.No significant effect of PSD was observed for physiological parameters (i.e., HR and SaO2). However, a significant alteration of resting ultra-sensitive C-reactive protein (P < 0.05) and myoglobin (MYO) (P < 0.01) levels was detected after PSDEN. Furthermore, all biomarkers related to muscle and cardiac injuries were altered by exercise. Likewise, compared to RN, PSD affected creatine phosphokinase and MYO levels in response to exercise (P < 0.05).The present study indicates that PSDEN increase the resting us-CRP and MYO levels, and that the two types of PSD increase the CPK and MYO levels in response to acute intermittent exercise, among Taekwondo athletes, in the evening of the following day. However, no rise of the physiological responses has been observed after the two types of PSD, at rest and in response to the exercise.

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