Chtourou CI 2011 Diurnal Variation Wingate-Test Performance Associated electromiographic parameters

THE EFFECT OF TRAINING AT THE SAME TIME OF DAY

AND TAPERING PERIOD ON THE DIURNAL VARIATION

OF SHORT EXERCISE PERFORMANCES

HAMDI CHTOUROU,1,2 ANIS CHAOUACHI,1 TARAK DRISS,3 MOHAMED DOGUI,4 DAVID G. BEHM,5

KARIM CHAMARI,1 AND NIZAR SOUISSI1,6

1Tunisian Research Laboratory ‘‘Sports Performance Optimization’’ National Center of Medicine and Science in Sports (CNMSS),Tunis, Tunisia; 2Research Unit, High Institute of Sport and Physical Education, Sfax, Tunisia; 3Research Center on Sport andMovement, UFR STAPS, Paris Ouest Nanterre University, Paris, France; 4Research Unit ‘‘Neurophysiology of Vigilance, ofAttention and Performances’’ 99/UR/08-23, Service of Functional Exploration of the Nervous System, CHU Sahloul, Sousse,Tunisia; 5School of Human Kinetics and Recreation; Memorial University of Newfoundland, St. John’s Newfoundland, Canada,A1C 5S7; and 6High Institute of Sport and Physical Education, Manouba University, Ksar-Said, Tunisia.

ABSTRACT

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 25(X): 000–000,

2011—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 one’s 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.

KEY WORDS circadian rhythm, muscle power, muscle strength,

time-of-day-specific training, taper

INTRODUCTION

It has been well documented that maximal short-termperformances fluctuate with time of day, with morningnadirs and afternoon maximum values (23,25,26,28).These daily variations have been found to range from

3 to 21.2%, depending on the population tested, the musclegroups, and the experimental design (20).

The diurnal variations in short-term maximal exercises (#1minute) mainly involving anaerobic metabolism can beinfluenced by several factors such as sleep deprivation (29),warm-up duration (26), and time of day of the training(22–24,27). Based on previous literature, training in themorning can (a) improve typically poor morning anaerobicperformance to the same or an even higher level as theirnormal daily peak typically observed in the late afternoon and(b) decrease the amplitude of the diurnal variations (22–24,27).However, training in the evening hours can increase theamplitude of the daily variations of neuromuscular perform-ances (27). Souissi et al. (27) and Sedliak et al. (22–24)demonstrated that greater improvements in anaerobic per-formances occurred at the time of the day at which resistancetraining was regularly performed. However, Souissi et al. (27)found stronger temporal specificity of the morning group thandid Sedliak et al. (22–24). Moreover, Sedliak et al. (22–24)

Address correspondence to Hamdi Chtourou, [email protected].

0(0)/1–12

Journal of Strength and Conditioning ResearchCopyright � 2011 by Lippincott Williams & Wilkins

VOLUME 0 | NUMBER 0 | MONTH 2011 | 1

reported no significant time of day–specific adaptations aftertraining in the evening hours. Recently, Blonc et al. (4) failed toshow any time-of-day effects on either performance or trainingbenefits. The discrepancies in the findings between thesestudies might be partly because of an accumulated neuro-muscular fatigue or to a detraining phase, which may impairthe performance in the posttraining test sessions. In fact, in theSedliak et al. studies (22–24), the posttraining test sessionswere performed after an intensive resistance training phase,which could induce accumulated neuromuscular fatigue(9,14). However, in the Souissi et al. study (27), the posttrainingtest sessions were performed after 2 weeks of trainingcessation, which can lead to reduced adaptation levels andthen performances (9,14).

To reach peak performance and to avoid neuromuscularfatigue, coaches and researchers with an interest in resistancetraining have attempted to identify the proper handling ofprogram variables (e.g., intensity, frequency, and volume) (16).It is believed that the short-term reduction of the trainingvolume while the intensity is kept high is a well-knownpractice used to maximize performance after an intensetraining period (10,11,14,17,19). This process, known as taper,can have a major influence on the athlete’s performance level(14,17). A recent meta-analysis suggests that tapering canreduce accumulated fatigue after a training period (8,17) andimprove performances by 0.5–6% (18). Regarding anaerobicperformances, Gibala et al. (9) examined the effects of 10 days

of tapering after 3 weeks ofresistance training and reportedsignificant increases in isometricpeak torque and low-velocityisokinetic strength performanceof the elbow flexors. Recently,Izquierdo et al. (14) found that4 weeks of tapering resultedin further increases in maximalstrength and muscle power after16 weeks of periodized resis-tance training. Thus, the incor-poration of a short-term

tapering period after a resistance training program may allowphysical and mental recovery and seems to be effective inavoiding the negative impact of training stimuli before the startof new testing sessions or before a major competition inathletic performance.

In light of these observations, along with the fact that thereis a conflict in the literature with regard to the impact oftraining at the same time of day, we hypothesized that, byusing a taper period and controlling other variables such astraining intensity and volume, we could advance knowledgein the area of the temporal specificity of resistance trainingand tapering. The question then arises to determine iftapering period scheduled at a particular time of day can (a)induce further time-of-day–specific adaptation and (b) leadto similar or different improvements in anaerobic perform-ances (i.e., difference between training in the morning or inthe evening hours). It is critical, therefore, for athletesinterested in maximal performance, and coaches andresearchers, to determine the role of a taper periodscheduled in the morning or the evening hours to optimizetraining adaptability (strength and power gains) and to avoidoverreaching or overtraining.

In view of the above considerations, the purpose of thisstudy was twofold: (a) to determine the effect of 12 weeksof resistance training and 2 weeks of tapering scheduled in themorning or in the evening on the diurnal variations of short-term maximal performances and (b) to investigate the effect

TABLE 1. Physical characteristics of the MTG (n = 10), ETG (n = 11), and CG (n = 10).*†

MTG ETG CG

Age (y) 22.7 6 2.31 22.82 6 1.66 23.8 6 1.87Height (cm) 175.8 6 7.07 174.55 6 3.98 178 6 7.86Weight (kg) 77.38 6 11.61 72.41 6 5.93 75.23 6 14.22

*MTG = morning training group; ETG = evening training group; CG = control group.†Values are given as mean 6 SD.

Figure 1. Study design.

2 Journal of Strength and Conditioning Researchthe TM

Temporal Specificity of Tapering

of time of day of tapering on the improvements of theseperformances. We hypothesized that a tapering periodscheduled in the morning or in the evening may inducetime-of-day–specific adaptations and increases in short-termmaximal performances. However, to the authors’ knowledge,there are no studies to support this hypothesis.

METHODS

Experimental Approach to the Problem

There is a conflict in the literature with regard to the influenceof training at the same time of day on short-term maximalperformances. Therefore, by comparing 2 resistance trainingprograms, one scheduled in the morning and the other in theevening, we sought to investigate the importance of time ofday of training and tapering on the diurnal variation and theimprovements of anaerobic performances. To achieve this,the subjects performed maximal brief squat jumps (SJ),countermovement jumps (CMJ), maximal voluntary contrac-tion (MVC), and the Wingate tests before (T0) and after12 weeks of resistance training (T1) and after 2 weeks oftapering (T2). They were randomly assigned to eithera morning training group (MTG, who trained between0700 and 0800 hours, n = 10), evening training group (ETG,who trained between 1700 and 1800 hours, n = 11), ora control group (CG, did not train but participated in all thetests, n = 10). They performed the evaluation tests at 0700and 1700 hours. These time points were chosen because theycorrespond to the minimum and maximum day-time levelsof anaerobic performances (20). The dependent variableincluded the core temperature values and the SJ, CMJ, MVC,and the Wingate test’s performances (peak [Ppeak] and mean[Pmean] powers and fatigue index [FI]). The independentvariables included groups, periods, and time of day. The testsessions were conducted from January to May 2010.

Subjects

Thirty-one healthy male physical education students (age:23.1 6 1.98 years; height: 176.06 6 6.28 cm; and weight:74.92 6 10.88 kg) volunteered to participate in this study. Thecharacteristics of each group’s participants (mean 6 SD) areshown in Table 1. Initially, all the participants had exactly thesame time schedule at the university from sunrise to sunsetunder the control of the experimental team. The subjects hadtaken part in various recreational low-intensity physicalactivities such as walking, jogging, or aerobics in ouruniversity, but none of them had any background in regularresistance training (i.e., during the 6 months before thestudy). Medications, which are expected to affect physicalperformance, are prohibited. Before participation, all thesubjects were informed about the experimental procedures,the possible risks, and discomforts associated with the studyand signed a written informed consent. The study wasconducted according to the Declaration of Helsinki, and theprotocol was fully approved by the Clinical Research EthicsCommittee and the Ethic Committee of the National Center

of Medicine and Science of Sports of Tunis before thecommencement of the assessments. The subjects werecategorized either as ‘‘moderately morning type’’ (n = 10)or as ‘‘neither type’’ (n = 21) on the basis of their answers tothe Horne and Ostberg’s (13) self-assessment questionnaire,which assesses morningness eveningness.

Procedures

One week before the actual measurements, the subjects werefamiliarized with the experimental testingprocedureson acontrolday. Anthropometrical measurements and resistance loadverifications for the experimental exercises were also determinedfor each subject at this time. Thereafter, the subjects were testedon 6 different occasions in a randomized order using identicalprotocols (SJ, CMJ, MVC, and Wingate test, with a recoveryperiod of at least 15 minutes between 2 successive tests): beforetraining (T0), after training (T1), and after tapering (T2) inthe morning and in the evening. The test sessions wereperformed on separate days with only 1 test session a day,allowing a recovery period $36 hours. Three sessions wereconducted in the morning (0700 hours) and 3 in the evening(1700 hours) (Figure 1). The MTG trained only in the morningand performed tests at 0700 and 1700 hours. However, the ETGtrained only in the evening and were also tested at both 0700 and1700 hours. The morning and evening tests were scheduled atthe same time of day as the training sessions. Additionally, thesubjects were dismissed if they were absent for .3 consecutivebouts. The average number of training sessions completed was37.33 6 1.55, with all the subjects completing $35 sessions.

To minimize confounding factors, instructions related tosleep and diet were given to the subjects before theexperiment. On the night preceding each test session, thesubjects were asked to keep their usual sleeping habits, witha minimum of 6 hours sleep. During the period ofinvestigation, they were prohibited from consuming anyknown stimuli (e.g., caffeine) or depressants (e.g., alcohol) thatcould possibly enhance or compromise wakefulness. More-over, the participants were requested to maintain theirhabitual physical activity and to avoid strenuous activity in theday before testing throughout the study. The actimetry(Actiwatch�; Cambridge Neurotechnology Ltd., Cambridge,United Kingdom; Mini Mitter, Respironics Inc., Bend, OR,USA) allowed us to check that their sleep duration was not,6 hours and that they did not engage in any fatiguingexercise during the testing period. Before the morning testsessions, the subjects were asked to come to the laboratory at06:00 hours in a fasting state. Only 1 glass (150–200 ml) ofwater was allowed, to avoid the postprandial thermogenesiseffects. Before the evening test sessions, they had the samestandard isocaloric meal at 12:00 hours. The overall dailyenergy intake goal was set at 10.5 MJ (2,500 kcal) per capitaper day. After lunch, only water was allowed ad libitum.During the entire experimental period, the mean ambienttemperature and relative humidity of the laboratory werekept stable (20.9 6 1.2�C and 37.5 6 7.3%, respectively).


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Subjects’ oral temperature was recorded using a digital clinicalthermometer (Omron�, Paris, France; accuracy 6 0.05�C) inthe beginning of each testing session after they lay in a supineposition for 15 minutes to reduce the effect of prior activity.

Training Programs

Both groups (MTG and ETG) trained the knee extensors andflexors muscles of both legs 3 times per week for 12 weeks(from T0 to T1). Subsequently, the subjects participated ina 2 weeks’ period of tapering (from T1 to T2). The trainingprogram (designed to enhance muscle size and strength) wassimilar so that the MTG and the ETG trained in an identicalmanner throughout the study (e.g., performed the sameexercises, repetitions, number of sets). During the course ofthe 12 weeks’ training period, the training sessions werestandardized to consist of 3 sets of 4 exercises (Squat, Legpress, Leg extension, and Leg curl). Training intensity wasestablished as 10 repetitions to failure per set (10 repetitionmaximum [10RM]: weight was assessed as that which couldjust be lifted 10 times) and adjusted as performance improvedto stay within the desired RM training zone. Two minutesrecovery was allowed between sets. During all the trainingsessions, if the load happened to become slightly too heavy, asit did in some cases, the subject was assisted slightly during thelast l–3 repetitions of the set. The training volumes presentedby multiplication of load, sets, and repetitions (sets 3

repetitions 3 load) over 1 training session and the weeklytraining volume were 3,185.71 and 9,557.14 kg, respectively.Each training session lasted approximately 1 hour. It waspreceded by 10 minutes of warm-up and concluded with 10minutes of cool-down. The warm-up included 8–10 repeti-tions using light weights for all exercises. Additionally, allresistance training sessions were supervised by one of theinvestigators during the span of investigation.

After the resistance training period, the subjects wereassigned to 2 weeks of tapering period conducted 2 days perweek. Tapering consisted of a period of decreased trainingvolume (i.e., � 20% over 1 training session and �50% over1 week) with increased intensity (i.e., from 10RM to 8RM).During this phase, the subjects performed 3 sets of the sameexercises (Squat, Leg press, Leg extension, and Leg curl) with3-minute rest periods between sets and exercises. All theexercises were performed with the maximum load possible toachieve 8 repetitions (8RM) in each set. During this taperingphase, the training volume (sets 3 repetitions 3 load) over1 training session and the weekly training volume was2,565.71 and 5,131.42 kg, respectively.

Wingate Test

The Wingate test was conducted on a friction-loaded cycleergometer (Monark 894E, Stockholm, Sweden) interfaced witha microcomputer. The cycle was equipped with toe clips toprevent the subject’s feet from slipping. The seat height andhandlebars were adjusted to each subject’s satisfaction. TheWingate test consisted of a 30-second maximal sprint againsta constant resistance related to body mass (0.087 kg� kg21

body mass) as proposed by Bar-Or (1). The test began froma rolling start, at 60 rpm against minimal resistance (weightbasket supported). When a constant pedal rate of 60 rpm wasachieved, a countdown of ‘‘3–2-1-go!’’ was given by theexperimenter. At the start signal, the test resistance wasapplied, and the subjects were instructed to pedal as fast asthey could during 30 seconds. During the test, the subjects hadto remain seated and were strongly encouraged to reach themaximal pedaling rate as quickly as possible. Every second,the power output was calculated by the computer and stored.The highest power output over 1 second (Ppeak) and the meanpower (Pmean), corresponding to the ratio between total work

done and time to completion(e.g., 30 seconds), were recordedat the end of the test. The FI(e.g., the percentage of decreasein power output) was equal tothe difference between the high-est (Ppeak) and lowest power(Plow) divided by the highestpower:

FI ¼ ðPpeak � PlowÞ=Ppeak:

Squat Jump and

Countermovement Jump Tests

The subjects were asked toperform a maximal vertical SJand CMJ without any loadon an infrared jump system(Optojump, Microgate, Bolza-no, Italy) interfaced with a mi-crocomputer. This system is

Figure 2. Mean and SD of oral temperature (n = 31) in the morning and the evening tests at T0, T1, and T2 for allgroups. ***Significant differences between the time points at the level p , 0.001.



developed to measure with 1023-second precision all flyingand ground contact times. Then, the calculations of the jumpheight are made. The Optojump photocells placed 6 mmfrom the ground were triggered by the feet of the participantat the instant of take-off and were stopped at the instant ofcontact upon landing. The subjects stood between two 1-minfrared sensor bars to perform the SJ and the CMJ.

In the SJ, the subjects lower themselves into a squat position(90�) and after a brief pause, jump upward as quickly and ashigh as possible. No downward motion is allowed immedi-ately before jumping upward. In contrast, in the CMJ subjectsinitiated the jump from an extended leg position, descendedto 90� knee flexion, and immediately performed an explosiveconcentric action for maximal height.

TABLE 2. Performances (mean 6 SD) on the Wingate test (Ppeak, Pmean, and FI) recorded at the 2 times of day in T0, T1,and T2.*

T0 T1 T2

07:00 h 17:00 h 07:00 h 17:00 h 07:00 h 17:00 h

MTGPpeak (W�kg21) 10.79 6 1.25 11.3 6 1.23† 11.34 6 1.04 11.63 6 1.6 11.58 6 0.83 11.74 6 1.18Pmean (W�kg21) 8.21 6 0.95 8.58 6 0.76‡ 8.42 6 0.81 8.58 6 0.83 8.54 6 0.8 8.64 6 0.77FI (%) 47.85 6 9.79 48.55 6 6.87 47.16 6 7.48 49.63 6 7.72 47.6 6 5.36 48.7 6 6.57

ETGPpeak (W�kg21) 10.89 6 1.07 11.58 6 1.01‡ 11.2 6 1.36 11.98 6 1.22‡ 11.31 6 1.2 12.2 6 1.05‡Pmean (W�kg21) 8.31 6 0.74 8.76 6 0.77‡ 8.5 6 0.8 9 6 0.78‡ 8.56 6 0.73 9.11 6 0.69‡FI (%) 46.76 6 7.9 46.62 6 9.18 48.82 6 9.59 49.82 6 8.82 47.91 6 6.67 48.55 6 8.08

CGPpeak (W�kg21) 11.06 6 0.87 11.45 6 0.92§ 11.08 6 0.93 11.34 6 0.87§ 11.07 6 0.84 11.38 6 0.8§Pmean (W�kg21) 8.13 6 0.58 8.39 6 0.72† 8.06 6 0.78 8.28 6 0.75§ 8.1 6 0.67 8.3 6 0.69§FI (%) 51.22 6 4.78 50.97 6 3.97 52.18 6 8.53 51.42 6 7.97 50 6 6.45 51.7 6 5.12

*MTG = morning training group; ETG = evening training group; CG = control group; T0 = before training; T1= after 12 weeks oftraining; T2 = after 2 weeks of tapering of training; Ppeak = peak performances; Pmean = mean performances; FI = fatigue index.

†Significant difference between 07:00 and 17:00 hours at the levels of p , 0.01.‡Significant difference between 07:00 and 17:00 hours at the levels of p , 0.001.§Significant difference between 07:00 and 17:00 hours at the levels of p , 0.05.

TABLE 3. Performances (mean 6 SD) on vertical jump tests (SJ and CMJ) recorded at the 2 times of day in T0, T1, and T2.*

T0 T1 T2

07:00 h 17:00 h 07:00 h 17:00 h 07:00 h 17:00 h

MTGSJ (cm) 29.48 6 5.57 32.48 6 6.28† 34.24 6 4.6 35.89 6 5.33 36.33 6 5.98 36.31 6 6.28CMJ (cm) 31.9 6 5.68 34.31 6 6.23‡ 34.92 6 4.13 36.31 6 6.48 36.46 6 5.83 37.07 6 5.19

ETGSJ (cm) 30.95 6 4.18 33.45 6 4.49† 33.61 6 4.46 37.67 6 7.81‡ 34.4 6 6.48§ 39.1 6 5.46kCMJ (cm) 33.17 6 3.34 36 6 4.97‡ 35.25 6 5.23 39.02 6 4.06‡ 37.23 6 4.86{ 41.25 6 3.65‡

CGSJ (cm) 27.91 6 3.87 30.45 6 5.49† 27.71 6 2.07 30.16 6 3.35† 28.06 6 2.15 30.12 6 3.24†CMJ (cm) 29.51 6 3.12 31.56 6 4.26‡ 30.03 6 3.43 31.96 6 4.19‡ 29.89 6 2.75 31.74 6 3.37‡

*MTG = morning training group; ETG = evening training group; CG = control group; T0 = before training; T1= after 12 weeks oftraining; T2 = after 2 weeks of tapering of training; SJ = squat jumps; CMJ = countermovement jumps.

†Significant difference between 07:00 and 17:00 hours at the levels of p , 0.05.‡Significant difference between 07:00 and 17:00 hours at the levels of p , 0.01.§ Significant difference between T0 and T2 at the levels of p , 0.01.{ Significant difference between T0 and T2 at the levels of p , 0.05.kSignificant difference between 07:00 and 17:00 hours at the levels of p , 0.001.



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In these jumping conditions, the subjects were instructed tokeeptheirhandsonthehipsandtominimizelateralandhorizontaldisplacements throughout the entire jump. Jumping height wascalculated from the flight time. The subjectsperformed 3maximaltrialsofeach jumptest interspersedwith15secondsof rest,andthepeak value was used for further analysis.

Maximal Voluntary Contraction

The subjects performed three 5-second MVC of the kneeextensors (120� knee flexion) of the dominant leg. They werestrongly encouraged while visual feedback was provided to reachmaximal level. The subjects were secured to a sitting position ina knee extension device (Leg extension machine, PANATTASPORT�, Italia). The torso was fixed with 2 horizontal safetybelts in the chest and waist area, and the upper extremities wereplaced next to the body holding handgrips. Moreover, boththighs were strapped. The force generated during the musclecontraction was measured by a strain gauge (Globus Italia,Codogne, Italy) properly mounted on the leg extension machinewith chains attached to the sliding axis of the seat. The signalfrom the strain gauge was sampled at 100 Hz and stored ona computer for later analysis with commercially availablesoftware (TCS-SUITE 400, Globus Italia).

The MVC was determined as the highest torque over the5-second duration. Three trials were performed in eachcondition, separated by 2-minute rest, and the highest valueswere retained for subsequent analyses.

Statistical Analyses

All statistical tests were processed using STATISTICASoftware (StatSoft, France). Mean, SD and standard error(SE) were calculated for the selected variables. The Shapiro-Wilk W-test of normality revealed that the data were normallydistributed. Once the assumption of normality was confirmed,parametric tests were performed. The effects of group, time ofday and training were verified by a 3-way analysis of variancewith repeated measures. As the CG was included to determinewhether the increase of performance is because of our trainingand tapering program or the physical activity at the university,data of this group were analyzed separately using a 2-wayanalysis of variance with repeated measures (3 [periods] 3 2[time of day]). The data of the MTG and ETG were analyzedusing a 3-way analysis of variance with repeated measures(2 [groups] 3 3 [periods] 3 2 [time of day]) using absolutevalues. To determine the difference between the MTG andthe ETG, the average of each independent variable recorded inthe morning and in the evening was calculated. Then, a 2-wayanalysis of variance with repeated measures (2 [groups] 3 3[periods]) was used to determine significant differences amongthe 3 periods. When appropriate, significant differencesbetween means were assessed using Tukey’s honestlysignificant difference (HSD) test procedure. Moreover,unpaired t-tests were used to compare relative changes (deltachange values) from T0 to T1 and T1 to T2 betweenthe MTG and ETG. Effect sizes were calculated as partial

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eta-squared hp2 to assess the practical significance of our

findings. Test-retest reliability was assessed by means ofintraclass correlation coefficients (ICCs) and standard error ofmeasurement (SEM). The statistical significance for allanalyses was set at p # 0.05.

RESULTS

Temperature

A significant main effect for time of day (F(1.9) = 2023.9,p , 0.001) demonstrated that the oral temperature improvedsignificantly from morning to evening measures (p , 0.001,Figure 2) with an amplitude (peak to trough) of approximately2.33 6 0.1%. There were no significant main effects for groups(F(2.18) = 0.40, p . 0.05) or periods (F(2.18) = 0.63, p . 0.05).Neither was there a significant groups 3 periods 3 time-of-day interaction (F(4.36) = 0.61, p . 0.05), indicating that thetime-of-day effects for all periods (T0, T1, and T2) did notchange with training or tapering at the same time of day.

Wingate Test

Mechanical parameters recorded during the Wingate test atT0, T1, and T2, in the morning and in the evening for all thegroups are given in Table 2.

Peak Power. The ICC and SEM for Ppeak showed high reliability(ICC .0.86 and absolute SEM , 0.4 W�kg21). Concerningthe CG, there was a significant main effect for time of day(F(1.9) = 23.06, p , 0.001, hp

2 = 0.81) indicating that Ppeak wassignificantly higher in the evening than in the morningduring T0, T1, and T2 (p , 0.05). In contrast, there was nomain effect for periods (F(2.18) = 0.97, p . 0.05, hp

2 = 0.04)and periods 3 time-of-day interaction (F(2.18) = 0.94, p . 0.05,hp

2 = 0.08).Concerning the 2 training groups, there was a significant

main effect for time of day (F(1.9) = 14.54, p , 0.01, hp2 = 0.67)

and periods (F(2.18) = 8.61, p , 0.01, hp2 = 0.62). However,

there was no main effect for groups (F(1.9) = 0.32, p . 0.05,hp

2 = 0.12) and groups 3 periods 3 time-of-day interaction(F(2.18) = 0.55, p . 0.05, hp

2 = 0.09). In T0, the post hocrevealed that, for the MTG and ETG, Ppeak improvedbetween the morning and the evening (p , 0.01 for MTGand p , 0.001 for ETG). These diurnal variations persisted inthe ETG (p , 0.001) and disappeared in the MTG (p . 0.05)in T1 and T2. Data related to the amplitude of these diurnalvariations are presented in Table 4.

When we consider the effect of training and tapering, therewas a significant main effect for periods (F(1.9) = 8.61, p , 0.01,hp

2 = 0.75). The post hoc analysis showed that Ppeak wassignificantly higher in T1 than in T0 (p , 0.01) and in T2 thanin T0 (p , 0.001) in the MTG and ETG (Table 5). However,there was no significant difference in the relative increasebetween the MTG and the ETG at T1 (t = 0.38, p . 0.05)and T2 (t = 0.18, p . 0.05) (Table 6).

Mean Power. The ICC and SEM for Pmean showed highreliability (ICC .0.81 and absolute SEM , 0.3 W�kg21). For

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the CG, there was a significant main effect for time of day(F(1.9) = 15.05, p , 0.01, hp

2 = 0.49) indicating that Pmean

improved significantly from morning to evening during the3 periods (p , 0.01 in T0 and p , 0.05 in T1 and T2).However, the main effect for periods (F(2.18) = 1.5, p . 0.05,hp

2 = 0.05) and the periods 3 time-of-day interaction(F(2.18) = 0.16, p . 0.05, hp

2 = 0.07) were not significant.For the 2 training groups, the main effect for time of day

(F(1.9) = 17.74, p , 0.01, hp2 = 0.78) and periods (F(2.18) = 5.04,

p , 0.05, hp2 = 0.38) were significant. However, the main

effects for groups (F(1.9) = 0.72, p . 0.05, hp2 = 0.03) and the

groups 3 periods 3 time-of-day interaction (F(2.18) = 0.36,p . 0.05, hp

2 = 0.07) were not significant. In T0, Pmean

was significantly higher in the evening than in the morning(p , 0.001). This daily variation disappeared in the MTG and

persisted in the ETG (p , 0.001) in T1 and T2. Data relatedto the ranges of the diurnal gains are presented in Table 4.

In T1 and T2, there was a significant main effect for periods(F(1.9) = 5.06, p , 0.01, hp

2 = 0.62) with post hoc analysisshowed that Pmean was significantly higher in T1 than T0(p , 0.05) only in the ETG and in T2 than in T0 (p , 0.05) inthe MTG and ETG (Table 5). However, there was nosignificant difference in the relative increase between theMTG and the ETG at T1 (t = 0.4, p . 0.05) and T2(t = 0.1, p . 0.05) (Table 6).

Fatigue Index. For the FI, the main effects for groups(F(2.18) = 1.03, p . 0.05), periods (F(2.18) = 1.82, p . 0.05)and time of day (F(1.9) = 1.67, p . 0.05) were not significant.Moreover, the groups 3 periods 3 time-of-day interaction(F(4.36) = 0.42, p . 0.05) was not significant.

Maximal Voluntary

Contraction

The ICC and SEM showed veryhigh reliability (ICC . 0.95 andabsolute SEM , 42.12 N). Forthe CG, there was a signifi-cant main effect for time ofday (F(1.9) = 11.73, p , 0.01,hp

2 = 0.7) indicating a significantdiurnal variation of MVC withhigher values observed in theevening during T0, T1, and T2(p , 0.01) (Figure 3). In contrast,there was no main effect forperiods (F(2.18) = 0.12, p . 0.05,hp

2 = 0.07) and periods 3 time-of-day interaction (F(2.18) = 0.1,p . 0.05, hp

2 = 0.03).For the MTG and ETG, the

main effects for time of day(F(1.9) = 31.35, p , 0.001, hp

2 =

TABLE 6. The relative increase (mean 6 SE) between T0 and T1 and between T1 and T2 for the 2 training groups.

MTG ETG

T1 T2 T1 T2

Ppeak (W�kg21) 3.56 6 1.82 1.7 6 0.95 2.58 6 1.9 1.46 6 0.88Pmean (W�kg21) 1.22 6 1.05 1.03 6 0.47 2.23 6 1.86 0.96 6 0.44MVC (N) 11.35 6 2.38 4.8 6 0.53 10.61 6 4.73 8.39 6 1.83SJ (cm) 11.24 6 3.93 1.94 6 4.29 8.41 6 3.53 2.21 6 1.66CMJ (cm) 7.13 6 2.06 2.78 6 2.03 6.08 6 2.45 5.3 6 1.33

*MTG = morning training group; ETG = evening training group; CG = control group; T0 = before training; T1= after 12 weeks oftraining; T2 = after 2 weeks of tapering of training; SJ = squat jumps; CMJ = countermovement jumps; MVC = maximal voluntarycontraction.

Figure 3. Relative changes in maximal voluntary contraction (MVC; mean 6 SE) at 07:00 and 17:00 hours in T0,T1, and T2 for the control group (CG; n = 10). *, **Significant differences between the time points at the levels ofp , 0.05 and p , 0.01, respectively.



0.87) and periods (F(2.18) = 23.97, p , 0.001, hp2 = 0.84) and the

groups 3 periods 3 time-of-day interaction (F(2.18) = 13.31,p , 0.001, hp

2 = 0.53) were significant. However, there was nomain effect for groups (F(1.9) = 0.1, p . 0.05, hp

2 = 0.04). In T0,MVC values were significantly higher at 1700 than 0700 hours(p , 0.001 and p , 0.01 for MTG and ETG, respectively). InT1 and T2, the post hoc analysis revealed that these diurnalfluctuations persisted in the ETG (Figure 4) (p , 0.001).However, the daily variations on MVC disappeared withtraining in the morning hours (Figure 5). The amplitudes ofthese diurnal variations are presented in Table 4.

Regarding the effect of train-ing and tapering, there wasa significant main effect forperiods (F(1.9) = 23.97, p ,

0.001, hp2 = 0.85). The post

hoc analysis showed that MVCvalues improved significantlyfrom T0 to T1 and from T0to T2 (p , 0.001) (Table 5).However, there was no signif-icant difference in the relativeincrease between the MTG andthe ETG at T1 (t = 0.14, p .

0.05) and T2 (t = 1.8, p . 0.05)(Table 6).

Jump Performances

Table 3 presents the SJ andCMJ results calculated in themorning and in the evening, inT0, T1, and T2, for all groups.

Squat Jump. The ICC andSEM showed high reliability (ICC . 0.86 and absolute SEM, 1.66 cm). Concerning the CG, there was a significant maineffect for time of day (F(1.9) = 9.62, p , 0.05, hp

2 = 0.73)indicating that SJ was significantly higher in the evening than inthe morning during the 3 periods (p , 0.05). Nonetheless, therewas no main effect for periods (F(2.18) = 0.1, p . 0.05, hp

2 = 0.08)and periods 3 time-of-day interaction (F(2.18) = 0.08, p . 0.05,hp

2 = 0.05).Concerning the MTG and ETG, there were significant

main effects for time of day (F(1.9) = 10.57, p , 0.01, hp2 = 0.66)

and periods (F(2.18) = 17.32, p , 0.001, hp2 = 0.69). In contrast,

there was no main effect forgroups (F(1.9) = 0.07, p . 0.05,hp

2 = 0.06) and groups 3

periods 3 time-of-day interac-tion (F(2.18) = 2.89, p . 0.05, hp

2

= 0.08). In T0, the post hocanalysis showed that SJ valuesrecorded at 1700 hours werehigher than those recorded at0700 hours (p , 0.05). In T1 andT2, these diurnal fluctuationspersisted in the ETG (p , 0.01and p , 0.001, respectively) anddisappeared in the MTG. Datarelated to the amplitudes areshown in Table 4.

Regarding the effect of trainingand tapering, there was a signifi-cant main effect for periods(F(1.9) = 17.23, p , 0.001,hp

2 = 0.59) with post hoc ana-lysis showed that SJ improved

Figure 4. Relative changes in maximal voluntary contraction (MVC; mean 6 SE) at 07:00 and 17:00 hours in T0,T1, and T2 for the evening training group (ETG; n = 11). **,***Significant differences between the time points at thelevels of p , 0.01 and p , 0.001, respectively.

Figure 5. Relative changes in maximal voluntary contraction (MVC; mean 6 SE) at 07:00 and 17:00 hours in T0,T1, and T2 for the morning training group (MTG; n = 10). ***Significant differences between the time points at thelevel of p , 0.001.



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significantly from T0 to T1 (p , 0.01 for the MTG and p , 0.05for the ETG) and from T0 to T2 (p , 0.01) (Table 5). However,the relative increases between the MTG and the ETG at T1(t = 0.5, p . 0.05) and T2 (t = 0.05, p . 0.05) were not significant(Table 6).

Countermovement Jump. The ICC and SEM for CMJ showedvery high reliability (ICC . 0.96 and absolute SEM , 1.06cm). For the CG, there was a significant main effect for timeof day (F(1.9) = 10.41, p , 0.05, hp

2 = 0.41) indicating thatCMJ was improved significantly from morning to eveningduring T0, T1, and T2 (p , 0.01). However, there was nomain effect for periods (F(2.18) = 0.1, p . 0.05, hp

2 = 0.04) andperiods 3 time-of-day interaction (F(2.18) = 0.04, p . 0.05,hp

2 = 0.03).For the 2 training groups, significant main effects for time of

day (F(1.9) = 59.87, p , 0.001, hp2 = 0.78) and periods (F(2.18) =

31.2, p , 0.001, hp2 = 0.8) were evident. However, the groups

effect (F(1.9) = 1.07, p . 0.05, hp2 = 0.05) and the groups 3

periods 3 time-of-day interaction (F(2.18) = 0.58, p . 0.05,hp

2 = 0.04) were not significant. In T0, the post hoc revealedthat the 2 training groups behaved similarly; CMJ augmentedbetween the morning and evening (p , 0.05 and p , 0.01 forthe MTG and ETG, respectively). In T1 and T2, these diurnalvariations persisted in the ETG and disappeared in the MTG.The amplitudes of the diurnal rhythm are shown in Table 4.

After training and tapering, there was a significant maineffect for periods (F(1.9) = 32.1, p , 0.001, hp

2 = 0.68). Thepost hoc analysis showed that CMJ was significantly higherin T1 and T2 than in T0 (p , 0.05 and p , 0.001,respectively) in the MTG and ETG (Table 5). However, therewas no significant difference in the relative increase betweenthe MTG and the ETG at T1 (t = 0.33, p . 0.05) and T2(t = 1.7, p . 0.05) (Table 6).

DISCUSSION

The aim of this study was to (a) examine the effect of 12 weeksof resistance training and 2 weeks of tapering on the diurnalpatterns of short-term maximal performances and (b) toassess the effect of time of day of tapering on the improvementof these anaerobic performances. The major result of thisstudy was that 12 weeks of resistance training and 2 weeks oftapering performed either in the morning or in the eveninghours resulted in significant increases in anaerobic perform-ances. However, the magnitude of gains was similar aftertraining and tapering in the morning or in the evening hours.

In T0, short-term maximal performances (i.e., Wingate test,SJ, CMJ, and MVC) were significantly higher in the evening(1700–1800 hours) compared with that in the morning testsessions (0700–0800 hours), with amplitudes amounting tobetween 3.01 6 2.24 and 14.6 6 7.68%. These results confirmthose obtained by others (2,15,20,23–28), who observeda significant diurnal variation during various short durationtasks. Moreover, the gains observed in this study are inaccordance with the amplitude (peak-to-trough variation)

found in other studies (3–21.2%) (20). The exact underlyingmechanisms are still not known, but some authors (2,15)have hypothesized a causal link between the temporalfluctuation in core temperature and the diurnal variation inmuscular strength and power. In agreement with this, thepresent results showed a significant diurnal variation in oraltemperature. The higher body temperature may enhancemetabolic reactions, increase the extensibility of connectivetissue, reduce muscle viscosity, and increase the conductionvelocity of action potentials (28). However, in our study, theamplitude of variation in oral temperature observed over theday was low (;2%), and this seems insufficient to entirelyexplain the changes observed in the muscle contractionproperties (e.g., differences between 3 and 41% in shortduration exercise performances). Thus, the diurnal difference incore temperature is not the only explanation of the time-of-dayeffects on anaerobic performances. Recent findings havesuggested that the diurnal variation in short-term anaerobicperformances has been linked to variation in both central(neural input to the muscles) and peripheral (contractile state ofthe muscle) mechanisms across the day (7). Moreover, toexplain the diurnal variations in muscular power, Souissi et al.(25) have suggested that the daily variations during the Wingatetest is mainly because of a higher aerobic contribution in energyproduction (26), faster _VO2 kinetics, and better net efficiency(relationship between work performed and energy expendedabove that at rest) in the evening than in the morning (6).

The major result of this study was that 12 weeks ofresistance training modified the diurnal variations of anaerobicperformances with a greater improvement of these perform-ances at the time of day at which training was conducted.Moreover, the 2 weeks of tapering resulted in further time-of-day–specific adaptations and increased short-term anaerobicperformances. In fact, after these 2 periods, the typical diurnalpattern of anaerobic performances was blunted in the MTGand persisted with higher amplitudes in the ETG.

Although Blonc et al. (4) reported no significant training ata specific hour effect on SJ and CMJ performances after5 weeks of training (i.e., sprints, jumps, and others exercises),the present findings are consistent, in part, with those ofSouissi et al. (27) and Sedliak et al. (22–24). Souissi et al. (27)showed that 6 weeks of resistance training enhanced short-term anaerobic performances and induced a significant time-of-day–specific adaptation. Recently, Sedliak et al. (22–24)showed that diurnal variations during anaerobic tasksdecreased after 10 weeks of resistance training in the MTGbut not in the ETG and CG. However, the adaptations toresistance training of the MTG in this study were comparablewith the results of Sedliak et al. (22–24) and somewhat lesspronounced than those of Souissi et al. (27) after 12 weeks oftraining. After 2 weeks of the tapering phase, the presentresults were somewhat comparable with the results of Souissiet al. (27). In our opinion, it is possible that the 10 weekstraining period (especially the intensive phase performedduring the last 5 weeks) in the Sedliak et al. studies (22–24)



may have induced accumulated neuromuscular fatigue andcould have even led to reduced performances in theposttraining test sessions (19). Regarding training in theevening hours, the present results are in line with those ofSedliak et al. (22–24) who observed that the ETG improvedtheir anaerobic performances in the morning and in theevening. In contrast, Souissi et al. (27) showed that the ETGenhanced their performances only in the evening. Thediscrepancies between the present findings and those ofSouissi et al. (27) might be because of the enhancement ofperformances during this study tapering program anda decreased performance after training cessation in Souissiet al.’s study. In fact, to avoid detraining and maintain orimprove training adaptations and performances before a newtest sessions or a major competition, it is important to reducethe training load (i.e., especially by a reduction in the trainingvolume) (14,16–18). Moreover, Gibala et al. (9) showed thatonly 10 days of detraining resulted in a significant decrease inanaerobic performances (;8%).

The present results underscore the importance of thetemporal specificity of training and tapering. However, themechanisms responsible for the purported time-of-day–specific adaptations remain elusive. It appears that perform-ances during anaerobic tasks are dependent on a number oftime-dependent factors such as neuromuscular and hormonalsystems. Testosterone and cortisol have repeatedly been linkedwith resistance training adaptations, and higher concentra-tions appear preferential (12). Bird and Tarpenning (3)showed higher testosterone and cortisol levels were obtainedafter evening than after morning resistance training sessions.These results suggest that optimal adaptations to resistancetraining seem to occur in the evening (12). However, Sedliaket al. (24) showed that only cortisol concentrations decreasedsignificantly in the MTG, whereas training in the morning orevening hours had no effect on resting serum testosteroneconcentrations. These authors suggested that this reduction inserum cortisol may presumably be because of a decreasedanticipatory psychological stress before the morning testsessions. Another possible explanation may stem fromneuromuscular adaptations to resistance training. However,Sedliak et al. (23) failed to show any adaptation to resistancetraining scheduled repeatedly at a particular time of the day,on the electromyography activity of the knee extensors duringunilateral isometric knee extension peak torque. Thus, theauthors suggested that peripheral rather than neural adapta-tions are the main source of temporal specificity in resistancetraining. More recently, Sedliak et al. (22) observed that themagnitude of muscular hypertrophy (quadriceps femoriscross-sectional areas and volume) did not differ after trainingin the morning or in the evening hours.

Regarding the adaptations to the tapering phase after intensetraining, the present results showed significant improvement inshort-term performances. These findings are consistent withthose of some previous research reporting significant increasesin isometric peak torque and low-velocity isokinetic strength

performance of the elbow flexors (9) and on maximal strength(10,11) and muscle power (14) after 3–16 weeks of resistancetraining. Moreover, although there is a tendency to be higherin the evening than in the morning (e.g., 1.9 vs. 2.2% for the SJ,2.8 vs. 5.3% for the CMJ, and 4.8 vs. 8.4% for MVC in themorning and in the evening, respectively), our results showedthat the improvements of performances after the taperingperiod were similar (no statistical significant difference) aftertraining in the morning or in the evening hours. Because this isthe first study examining the effect of tapering at different timeof the day on short-term maximal performance, it is difficult tocompare the present results referring to the literature.Although speculative, it is possible that the lack of differencebetween morning and evening tapering may be explained inpart by this study’ choice of the step taper type (i.e., a sudden,standardized reduction). In fact, although it has been wellestablished that performance improvement after a taperingphase was more sensitive to reductions in training volume thanto manipulation of other training variables (5,21), someresearchers consider that a fast decay of training volumeduring this phase is more likely to enhance subsequentperformance than a slow decay or step taper (21). Moreover,most experimental and observation research on tapering in thescientific literature has been conducted with individual sportsand events (aerobic exercises). Individual sports wherein taperhas been examined include running, swimming, cycling, andtriathlon (21). However, there is little information available onthe prescription of the key elements of the taper (e.g., volume,intensity) after a resistance training period. Thus, a comparativestudy using different types of taper would be necessaryto understand the true importance of tapering in the morningor in the evening hours. Moreover, further research is requiredto identify the mechanisms by which taper may improveshort-term performances after evening or morning training. Inthis context, hormonal markers such as plasma levels oftestosterone and cortisol have been proposed as physiologicalmarkers to evaluate the tissue remodeling process and otherrelated mechanisms involved for adaptations during a strengthtraining period (14) and should be measured in such studies.

PRACTICAL APPLICATIONS

In summary, the findings of this study suggest that resistancetraining and tapering at the same time of day have thepotential to alter normal diurnal variation in muscle strengthand power. Indeed, adaptation to resistance training andtapering is greater at the time of the day at which training isperformed than at other times. Moreover, resistance trainingand tapering performed in the morning hours can improvetypically poor morning performances to the same or evenhigher level as their normal daily peaks typically observed inthe evening. Moreover, the present results indicated that theincrease of short-term performances after a tapering phasewas unaffected by the time of the day of training. Thus,strength and power athletes required to compete at a certaintime of day (i.e., when the time of competition is known) may



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be advised to coincide training and tapering hours with thetime of day at which one’s critical performance is planned.Moreover, if the time of competition in not known, a taperingphase after a resistance training program could be performedat any time of day with the same benefits.

ACKNOWLEDGMENTS

The authors thank all the subjects for their voluntaryparticipation in this study. The authors have no conflicts ofinterest that are directly relevant to the contents of thismanuscript. This study was financially supported by theMinistry of Scientific Research, Tunisia.

REFERENCES

1. Bar-Or, O. The Wingate anaerobic test, an update on methodology,reliability and validity. Sport Med 4: 381–394, 1987.

2. Bernard, T, Giacomoni, M, Gavarry, O, Seymat, M, and Falgairette, G.Time-of-day effects in maximal anaerobic leg exercise. Eur J ApplPhysiol Occup Physiol 77: 133–138, 1998.

3. Bird, SP and Tarpenning, KM. Influence of circadian time structureon acute hormonal responses to a single bout of heavy-resistanceexercise in weight-trained men. Chronobiol Int 21: 131–146, 2004.

4. Blonc, S, Perrot, S, Racinais, S, Aussepe, S, and Hue, O. Effects of 5 weeksof training at the same time of day on the diurnal variations of maximalmuscle power performance. J Strength Cond Res 24: 23–29, 2010.

5. Bosquet, L, Montpetit, J, Arvisais, D, and Mujika, I. Effects oftapering on performance: A meta-analysis. Med Sci Sports Exerc 39:1358–1365, 2007.

6. Brisswalter, J, Bieuzen, F, Giacomoni, M, Tricot, V, and Falgairette, G.Morning-to-evening differences in oxygen uptake kinetics in short-duration cycling exercise. Chronobiol Int 24: 495–506, 2007.

7. Castaingts, V, Martin, A, Van Hoecke, J, and Perot, C. Neuromus-cular efficiency of the triceps surae in induced and voluntarycontractions: Morning and evening evaluations. Chronobiol Int 21:631–643, 2004.

8. Garcia-Pallares, J, Sanchez-Medina, L, Perez, CE, Izquierdo-Gabarren, M, and Izquierdo M. Physiological effects of tapering anddetraining in world-class kayakers. Med Sci Sports Exerc 42:1209–1214, 2010.

9. Gibala, MJ, MacDougall, JD, and Sale, DG. The effects of taperingon strength performance in trained athletes. Int J Sports Med 15:492–497, 1994.

10. Gonzalez-Badillo, JJ, Gorostiaga, EM, Arellano, R, and Izquierdo, M.Moderate resistance training volume produces more favorablestrength gains than high or low volumes during a short-term trainingcycle. J Strength Cond Res 19: 689–697, 2005.

11. Gonzalez-Badillo, JJ, Izquierdo, M, and Gorostiaga, EM. Moderatevolume of high relative training intensity produces greater strengthgains compared with low and high volumes in competitiveweightlifters. J Strength Cond Res 20: 73–81, 2006.

12. Hayes, LD, Bickerstaff, GF, and Baker, JS. Interactions of cortisol,testosterone, and resistance training: Influence of circadian rhythms.Chronobiol Int 27: 675–705, 2010.

13. Horne, JA and Ostberg, O. A self-assessment questionnaire todetermine morningness-eveningness in human circadian rhythms.Int J Chronobiol 4: 97–110, 1976.

14. Izquierdo, M, Ibanez, J, Gonzalez-Badillo, JJ, Ratamess, NA,Kraemer, WJ, Hakkinen, K, Bonnabau, H, Granados, C, French,DN, and Gorostiaga, EM. Detraining and tapering effects onhormonal responses and strength performance. J Strength Cond Res21: 768–775, 2007.

15. Melhim, AF. Investigation of circadian rhythms in peak power andmean power of female physical education students. Int J Sports Med14: 303–306, 1993.

16. Mujika, I. Intense training: The key to optimal performance beforeand during the taper. Scand J Med Sci Sports 20: 24–31, 2010.

17. Mujika, I, Chaouachi, A, and Chamari, K. Precompetition taper andnutritional strategies: Special reference to training during Ramadanintermittent fast. Br J Sports Med 44: 495–501, 2010.

18. Mujika, I and Padilla, S. Scientific bases for precompetition taperingstrategies. Med Sci Sports Exerc 35: 1182–1187, 2003.

19. Mujika, I, Padilla, S, Pyne, D, and Busso, T. Physiological changesassociated with the pre-event taper in athletes. Sports Med 34:891–927, 2004.

20. Nicolas, A, Gauthier, A, Michaut, A, and Davenne, D. Effect ofcircadian rhythm of neuromuscular properties on muscle fatigueduring concentric and eccentric isokinetic actions. Isokinet Exerc Sci15: 117–129, 2007.

21. Pyne, DB, Mujika, I, and Reilly, T. Peaking for optimal performance:Research limitations and future directions. J Sports Sci27: 195–202,2009.

22. Sedliak, M, Finni, T, Cheng, S, Lind, M, and Hakkinen, K. Effect oftime-of-day-specific strength training on muscular hypertrophy inmen. J Strength Cond Res 23: 2451–2457, 2009.

23. Sedliak, M, Finni, T, Peltonen, J, and Hakkinen K. Effect oftime-of-day-specific strength training on maximum strength andEMG activity of the leg extensors in men. J Sports Sci 26:1005–1014, 2008.

24. Sedliak, M, Finni, T, Sulin, C, Kraemer, WJ, and Hakkinen K. Effectof time-of-day-specific strength training on serum hormoneconcentrations and isometric strength in men. Chronobiol Int 24:1159–1177, 2007.

25. Souissi, N, Bessot, N, Chamari, K, Gauthier, A, Sesboue, B, andDavenne, D.Effect of time of day on aerobic contribution to the 30-sWingate test performance. Chronobiol Int 24: 739–748, 2007.

26. Souissi, N, Driss, T, Chamari, K, Vandewalle, H, Davenne, D, Gam, A,Fillard, JR, and Jousselin, E. Diurnal variation in Wingate testperformances: Influence of active warm-up. Chronobiol Int 27:640–652, 2010.

27. Souissi, N, Gauthier, A, Sesboue, B, Larue, J, and Davenne, D. Effectsof regular training at the same time of day on diurnal fluctuations inmuscular performance. J Sports Sci 20: 929–937, 2002.

28. Souissi, N, Gauthier, A, Sesboue, B, Larue, J, and Davenne, D.Circadianrhythms in two types of anaerobic cycle leg exercise: force-velocity and30-s Wingate tests. Int J Sports Med 25: 14–19, 2004.

29. Souissi, N, Souissi, M, Souissi, H, Chamari, K, Tabka, Z, Dogui, M,and Davenne, D. Effect of time of day and partial sleep-deprivation on short-term, high power output. Chronobiol Int 25:1062–1076, 2008.



Chtourou CI 2011 Diurnal Variation Wingate-Test Performance Associated electromiographic parameters

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