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author:("sousse, nazar")
1.  Concomitant Effects of Ramadan Fasting and Time-Of-Day on Apolipoprotein AI, B, Lp-a and Homocysteine Responses during Aerobic Exercise in Tunisian Soccer Players 
PLoS ONE  2013;8(11):e79873.
Objective
To examine the time-of-day and Ramadan fasting (RF) effects on serum apolipoprotein-AI (Apo-AI) and B (Apo-B), lipoprotein particles-a (Lp-a), high-sensitive C-reactive-protein (hs-CRP), and homocysteine (Hcy) during the Yo-Yo intermittent recovery test (YYIRT).
Design
Performance and biochemical measures were completed at two times-of-day (07:00 and 17:00 h), 1-week before RF (BR), the second week of RF (SWR), and the fourth week of RF (ER).
Setting
For each session, subjects performed the YYIRT, and blood samples were taken before and 3-min after the test for biochemical measures.
Participants
Fifteen soccer players.
Main Outcome Measures
Total distance during the YYIRT, core temperature, body composition, dietary intakes, lipid (HDL-C, LDL-C, Apo-AI, B and Lp-a) and inflammatory (hs-CRP and Hcy) profiles.
Results
Performances during the YYIRT were higher in the evening than the morning BR (P < 0.05), but this fluctuation was not observed during RF. Moreover, LDL-C, ApoB, and Lp-a were stable throughout the daytime BR. However, during RF, they decreased at 17:00 h (P < 0.05). Likewise, HDL-C and Apo-AI increased after the exercise and were higher at 17:00 h BR (P < 0.001). Moreover, these parameters increased during RF (P < 0.01). Furthermore, Hcy and hs-CRP increased during the exercise (P < 0.01) with higher evening levels BR. During ER, the diurnal pattern of Hcy was inversed (P < 0.001).
Conclusions
This study concluded that caloric restriction induced by RF seems to ameliorate lipid and inflammatory markers of cardiovascular health during intermittent exercise performed in the evening.
doi:10.1371/journal.pone.0079873
PMCID: PMC3823586  PMID: 24244572
2.  Effect of Static and Dynamic Stretching on the Diurnal Variations of Jump Performance in Soccer Players 
PLoS ONE  2013;8(8):e70534.
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.
doi:10.1371/journal.pone.0070534
PMCID: PMC3734300  PMID: 23940589
3.  Biochemical Responses to Level-1 Yo-Yo Intermittent Recovery Test in Young Tunisian Football Players 
Purpose
The aim of this work was to investigate the metabolic and muscle damage responses after the level-1 Yo-Yo intermittent recovery test (YYIRT) in young football players.
Methods
Fifteen male football players (17.42 ± 0.2 yrs, 69.91 ± 4.4 kg, 178.64 ± 3.8 cm; mean ± SD) participated in this study. Fasting blood samples for various biochemical parameters (i.e. lactate (Lac), glucose (GLC), triglycerides (Tri), creatine kinase (CK), uric acid (UA)) collected from a forearm vein after 5-min of seated rest and 3-min after the test. Moreover, rating of perceived exertion (RPE) and maximal heart rate during and after the YYIRT were recorded.
Results
Mean levels of the selected biochemical markers were raised after the YYIRT exercise (P<0.001 for the other markers). Moreover, lipid parameters increased significantly after the test (P<0.01 for Tri and P<0.001 for HDL).
Conclusion
These findings confirm the higher metabolic demand of aerobic as well as anaerobic metabolism and reflect a significant mobilization of purine cycle during the YYIRT. The increase of muscle damage markers also reflects the higher anaerobic solicitation. From these findings, we can conclude the importance of aerobic and anaerobic metabolism during soccer-specific endurance performance (i.e. YYIRT, soccer match).
PMCID: PMC3685156  PMID: 23785572
Metabolic Responses; Intermittent Recovery Test; Lactate; Lipid Profile
4.  The Effects of Music on High-intensity Short-term Exercise in Well Trained Athletes 
Asian Journal of Sports Medicine  2012;3(4):233-238.
Purpose
The purpose of this investigation was to assess the effects of listening to music during warm-up on short-term supramaximal performances during the 30-s Wingate test in highly trained athletes.
Methods
Twelve young male athletes (20.6±1.8 yrs, 177±4.4 cm and 72.3±5.3 kg) underwent two Wingate tests in separate sessions with a recovery period of 48 h in-between, either after a 10 min of warm-up with (MWU) or without (NMWU) music. High tempo music (>120 to 140bpm) was selected for the study. Heart rate (HR) and rate of perceived exertion (RPE) were recorded after the warm-up (for HR = average of warm-up) and immediately after the Wingate test.
Results
HR, RPE and the fatigue index during the Wingate test are not affected by the incorporation of music during warm-up. However, power output (Ppeak and Pmean) was significantly higher after MWU than NMWU (P<0.05). The relative increases were 4.1 ± 3.6 and 4.0 ± 3.7 W·kg−1 for Ppeak and Pmean respectively. These findings demonstrated the beneficial effect of music during warm-up on short-term supramaximal performances.
Conclusions
As it's a legal method and an additional aid, music may be used during warm-up before performing activities requiring powerful lower limbs’ muscles contractions during short-term supramaximal exercises.
PMCID: PMC3525819  PMID: 23342221
Anaerobic Threshold; Warm-up Exercise; Wingate test; Music
5.  Effect of Short-Term Maximal Exercise on Biochemical Markers of Muscle Damage, Total Antioxidant Status, and Homocysteine Levels in Football Players 
Asian Journal of Sports Medicine  2012;3(4):239-246.
Purpose
Prolonged physical exercise results in transient elevations of biochemical markers of muscular damage. This study examined the effect of short-term maximal exercise on these markers, homocysteine levels (Hcy), and total antioxidant status (TAS) in trained subjects.
Methods
Eighteen male football players participated in this study. Blood samples were collected 5-min before and 3-min after a 30-s Wingate test.
Results
The results indicated that plasma biochemical markers of muscle injury increased significantly after the Wingate test (P<0.05). Moreover, significant increase of white blood Cells and their main subpopulations (i.e. monocytes, neutrophiles, and lymphocytes) (P<0.001) has been observed. Likewise, uric acid, total bilirubin, and TAS increased significantly after exercise (P<0.05). However, Hcy levels were unaffected by the Wingate test (for 3-min post-exercise measurement).
Conclusions
Short-term maximal exercise (e.g. 30-s Wingate test) is of sufficient intensity and duration to increase markers of muscle damage, and TAS; but not Hcy levels. Increases in the selected enzymes probably come primarily from muscle damage, rather than liver damage. Moreover, increase of TAS confirms the Wingate test induced oxidative stress.
PMCID: PMC3525820  PMID: 23342222
Muscles; Injury; Exercise; Homocysteine; Antioxidants; Wingate Test
6.  Diurnal Variations in Physical Performances Related to Football in Young Soccer Players 
Asian Journal of Sports Medicine  2012;3(3):139-144.
Purpose
This study investigated the effects of time-of-day on aerobic and anaerobic performances during the Yo-Yo, repeated sprint ability (RSA) and the Wingate tests in young soccer players.
Methods
In a counterbalanced and a random order, twenty junior male soccer players completed the Yo-Yo, the RSA, and the Wingate tests at two different times-of-day: 07:00 and 17:00 h. During the Yo-Yo test, the total distance (TD) covered and the estimated maximal aerobic velocity (MAV) were determined. The peak power (PP) during each sprint, the percentage of decrement of PP (PD) and total work (Wtotal) during the RSA test were, also, measured. In addition, during the Wingate test, the peak (Ppeak) and mean (Pmean) powers were recorded.
Results
During the Wingate test, Ppeak and Pmean were significantly higher at 17:00 than 07:00 h (P<0.05) with diurnal gains of 3.1±3.6 and 2.9±3.5% respectively. During the RSA test, PP during the first two sprints, Pdec and Wtotal were, also, higher in the evening (P<0.05) with amplitudes of 4.8±4.6, 3.1±3.0, 13.1±32.1, and 4.1±2.5% respectively. Likewise, TD and MAV during the Yo-Yo test were higher at 17:00 than 07:00 h with diurnal gains of 13.1±10.7 and 4.2±3.3 respectively.
Conclusions
The present study confirms the daily variations of both aerobic and anaerobic performances during the Yo-Yo, the RSA, and the Wingate tests in trained young Tunisian soccer players.
PMCID: PMC3445640  PMID: 23012632
Circadian Rhythm; Soccer Players; Aerobic Exercises; Anaerobic Exercises
7.  Time-of-Day Effects on EMG Parameters During the Wingate Test in Boys 
In boys, muscle power and strength fluctuate with time-of-day with morning nadirs and afternoon maximum values. However, the exact underlying mechanisms of this daily variation are not studied yet. Thus, the purpose of this study was to examine the time-of-day effects on electromyographic (EMG) parameters changes during a Wingate test in boys. Twenty-two boys performed a 30-s Wingate test (measurement of muscle power and fatigue) at 07:00 and 17:00-h on separate days. Surface EMG activity was recorded in the Vastus lateralis, rectus femoris and vastus medialis muscles throughout the test and analyzed over a 5-s span. The root-mean-square (RMS) and mean-power-frequency (MPF) were calculated. Neuromuscular efficiency (NME) was estimated from the ratio of power to RMS. Muscle power (8.22 ± 0.92 vs. 8.75 ± 0.99 W·kg-1 for peak power and 6.96 ± 0. 72 vs. 7.31 ± 0.77 W·kg-1 for mean power, p < 0.001) and fatigue (30.27 ± 7.98 vs. 34.5 ± 10. 15 %, p < 0.05) during the Wingate test increased significantly from morning to evening. Likewise, MPF (102.14 ± 18.15 vs. 92.38 ± 12.39 Hz during the first 5-s, p < 0.001) and NME (4.78 ± 1.7 vs. 3.88 ± 0.79 W·mV-1 during the first 5-s, p < 0.001) were higher in the evening than the morning; but no significant time-of-day effect was noticed for RMS. Taken together, these results suggest that peripheral mechanisms are more likely the cause of the child’s diurnal variations of muscle power and fatigue during the Wingate test.
Key pointsIn boys, performances during the Wingate test fluctuate with the time-of-day.MPF and NME are higher in the evening during the Wingate cycling test.RMS is unaffected by the time-of-day.The evening improvement in muscle power and fatigue is due to an enhancement of the muscle contractile properties.
PMCID: PMC3737921  PMID: 24149343
Dkwdurnal variation; muscle power; muscle fatigue; electromyography; pre-pubertal
8.  Comparison of Recovery Strategies on Maximal Force-Generating Capacity and Electromyographic Activity Level of the Knee Extensor Muscles 
Journal of Athletic Training  2011;46(4):386-394.
Context:
With regard to intermittent training exercise, the effects of the mode of recovery on subsequent performance are equivocal.
Objective:
To compare the effects of 3 types of recovery intervention on peak torque (PT) and electromyographic (EMG) activity of the knee extensor muscles after fatiguing isokinetic intermittent concentric exercise.
Design:
Crossover study.
Setting:
Research laboratory.
Patients or Other Participants:
Eight elite judo players (age = 18.4 ± 1.4 years, height = 180 ± 3 cm, mass = 77.0 ± 4.2 kg).
Interventions :
Participants completed 3 randomized sessions within 7 days. Each session consisted of 5 sets of 10 concentric knee extensions at 80% PT at 120°/s, with 3 minutes of recovery between sets. Recovery interventions were passive, active, and electromyostimulation. The PT and maximal EMG activity were recorded simultaneously while participants performed isokinetic dynamometer trials before and 3 minutes after the resistance exercise.
Main Outcome Measure(s):
The PT and maximal EMG activity from the knee extensors were quantified at isokinetic velocities of 60°/s, 120°/s, and 180°/s, with 5 repetitions at each velocity.
Results:
The reduction in PT observed after electromyo-stimulation was less than that seen after passive (P < .001) or active recovery (P < .001). The reduction in PT was less after passive recovery than after active recovery (P < .001). The maximal EMG activity level observed after electromyostimulation was higher than that seen after active recovery (P < .05).
Conclusions:
Electromyostimulation was an effective recovery tool in decreasing neuromuscular fatigue after high-intensity, intermittent isokinetic concentric exercise for the knee extensor muscles. Also, active recovery induced the greatest amount of neuromuscular fatigue.
PMCID: PMC3419150  PMID: 21944070
peak torque; isokinetic exercises; concentric exercises; high-intensity intermittent exercises
9.  Effect of Acute Maximal Exercise on Circulating Levels of Interleukin-12 during Ramadan Fasting 
Asian Journal of Sports Medicine  2011;2(3):154-160.
Purpose
The purpose of this study was to examine the effects of Ramadan fasting on circulating levels of interleukin-12 (IL-12) after a brief maximal exercise.
Methods
Nine subjects performed a Wingate test on three different occasions: (i) the first week of Ramadan (1WR), (ii) the fourth week of Ramadan (4WR), and (iii) three weeks after Ramadan (AR). Blood samples were taken before, immediately and 60 min after the exercise. Plasma concentrations of IL-12 were measured using enzyme-linked immunosorbent assay. Variance analysis revealed no significant effect of Ramadan on Ppeak and Pmean during the three testing periods.
Results
Considering the effect of Ramadan on plasma concentrations of IL-12, analysis of the variance revealed a significant Ramadan effect (F(2, 16)=66.27; P < 0.001) as well as a significant time effect (F(2, 16)= 120.66; P < 0.001). However, no significant (Ramadan × time) of test interaction (F(4, 32)=2.40; P>0.05). For all measures, IL-12 levels were lower during 1WR and 4WR in comparison with AR (P < 0.05). Considering the exercise effects, IL-12 levels measured immediately after the exercise were significantly higher than those measured before and at 60 minutes after the exercise (P < 0.001).
Conclusions
These results suggest that an acute intense exercise-induced IL-12 response is modified by daytime fasting and modifications in sleep schedule during Ramadan.
PMCID: PMC3289209  PMID: 22375234
Ramadan; Wingate Test; Interleukin-12; Immunity; Sleep Deprivation
10.  The Effect of Ramadan Fasting on Physical Performances, Mood State and Perceived Exertion in Young Footballers 
Asian Journal of Sports Medicine  2011;2(3):177-185.
Purpose
This study was designed to assess the effects of Ramadan fasting on the profile of mood state and perceived exertion in young soccer players and aerobic and anaerobic performances during the Yo-Yo, repeated sprint ability (RSA) and the Wingate tests.
Methods
Twenty junior male soccer players completed the Yo-Yo, the RSA, and the Wingate tests on three different occasions: one-week before Ramadan (BR), the second week (SWR) and the fourth week (ER) of Ramadan. The total distance (TD) covered and the estimated maximal aerobic velocity (MAV) during the Yo-Yo test were recorded. During the RSA test, peak power (PP) during each sprint, the percentage of decrement of PP (PD) and total work (Wtotal) were calculated. During the Wingate test, peak (Ppeak) and mean (Pmean) powers and fatigue index (FI) were recorded.
Results
TD and MAV (P=0.01) during the Yo-Yo test and PP (P=0.01, P=0.004, P=0.001, P=0.01, P=0.03 for sprints 1, 2, 3, 4, and 5, respectively) and Wtotal (P=0.02) during the RSA test were significantly higher during BR than ER. Furthermore, muscle fatigue during the RSA test increased significantly from BR to ER (P=0.01). Ppeak and Pmean during the Wingate test decreased significantly from BR to SWR and ER (P<0.0005). FI was higher during SWR (P=0.001) and ER (P<0.0005) than BR. In addition, rating of perceived exertion scores and fatigue estimated by the profile of mood state questionnaire were higher during Ramadan in comparison with BR.
Conclusions
The present study suggests that both aerobic and anaerobic performances during the Yo-Yo, the RSA and the Wingate tests were affected by Ramadan fasting in young soccer players.
PMCID: PMC3289213  PMID: 22375237
Ramadan Fasting; Fatigue; Aerobic Exercise; Anaerobic Exercise; Footballers

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