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The aim of this study was to determine the effect of time-of-day on sprint swimming performance and on upper and lower body, maximum strength, and muscle power. Twelve well-trained junior swimmers (six male and six female) were tested for bench press (BP) maximum strength and muscle power, jump height countermovement vertical jump (CMJ), crank-arm peak power (10s Wingate test), and time to complete 25 m freestyle at 10:00 am and at 18:00 pm in a random order. Performance was significantly enhanced in the pm compared to the am in 25 m swimming time (1.7%; p = 0.01), BP maximum strength (3.6%, p = 0.04, ES = 1.87), BP muscle power (5.1%, p = 0.00, ES = 2.10), and CMJ height (5.8%; p = 0.02), but not in crank-arm power (4.1%; p = 0.08). Time-of-day increased swimming performance in a magnitude of one-third of the effects observed on upper and lower neuromuscular power, which suggests that factors beyond peak muscle power (i.e. swimming technique) affect 25 m freestyle performance.
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Circadian rhythm effects on
neuromuscular and sprint swimming
performance
Jesús G. Pallarésa, Álvaro López-Samanesa, Jaime Morenoa,
Valentín E. Fernández-Elíasa, Juan Fernando Ortegaa & Ricardo
Mora-Rodrígueza
a Exercise Physiology Laboratory, University of Castilla-La Mancha,
Toledo, Spain.
Accepted author version posted online: 18 Apr 2013.Published
online: 25 Jun 2013.
To cite this article: Jesús G. Pallarés, Álvaro López-Samanes, Jaime Moreno, Valentín E.
Fernández-Elías, Juan Fernando Ortega & Ricardo Mora-Rodríguez (2014) Circadian rhythm effects
on neuromuscular and sprint swimming performance, Biological Rhythm Research, 45:1, 51-60, DOI:
10.1080/09291016.2013.797160
To link to this article: http://dx.doi.org/10.1080/09291016.2013.797160
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Downloaded by [HINARI] at 12:39 13 December 2013
Circadian rhythm effects on neuromuscular and sprint swimming
performance
Jesús G. Pallarés, Álvaro López-Samanes, Jaime Moreno, Valentín E. Fernández-Elías,
Juan Fernando Ortega and Ricardo Mora-Rodríguez*
Exercise Physiology Laboratory, University of Castilla-La Mancha, Toledo, Spain
(Received 6 March 2013; nal version received 3 April 2013)
The aim of this study was to determine the effect of time-of-day on sprint swimming
performance and on upper and lower body, maximum strength, and muscle power.
Twelve well-trained junior swimmers (six male and six female) were tested for
bench press (BP) maximum strength and muscle power, jump height countermove-
ment vertical jump (CMJ), crank-arm peak power (10s Wingate test), and time to
complete 25 m freestyle at 10:00 am and at 18:00 pm in a random order. Perfor-
mance was signicantly enhanced in the pm compared to the am in 25 m swimming
time (1.7%; p= 0.01), BP maximum strength (3.6%, p= 0.04, ES = 1.87), BP muscle
power (5.1%, p= 0.00, ES = 2.10), and CMJ height (5.8%; p= 0.02), but not in
crank-arm power (4.1%; p= 0.08). Time-of-day increased swimming performance in
a magnitude of one-third of the effects observed on upper and lower neuromuscular
power, which suggests that factors beyond peak muscle power (i.e. swimming
technique) affect 25 m freestyle performance.
Keywords: time-of-day; chronobiology; bench press; crank-arm Wingate; muscle
power; muscle strength
1. Introduction
During the day, the different aspects of physical performance (i.e. muscle endurance,
muscle power, and cardiorespiratory endurance) oscillate, scoring higher during midday
and early evening, and being depressed during the late night and early morning hours
(Baxter & Reilly 1983; Kline et al. 2007; Souissi et al. 2007; Sedliak et al. 2008;
Souissi et al. 2010; Taylor et al. 2010). Accompanying these diurnal changes of motor
performance, researchers have found changes on basal body temperature and blood
concentration of hormones, which in turn, could affect body uids, muscle metabolism,
and the cardiovascular response to exercise (e.g. heart rate and blood pressure)
(Atkinson & Reilly 1996; Decostre et al. 2005). Other studies, focusing on the effects
of circadian rhythm on the muscle itself, suggest alterations in the actinmyosin cross-
bridging processes (Starkie et al. 1999), phosphagen metabolism, and muscle buffering
capacity (Atkinson & Reilly 1996). Thus, circadian rhythm may have a profound
impact on motor performance through systemic and local muscle mechanisms that are
still open for clarication.
The changes in motor performance associated with circadian rhythm have been
mostly described for long- and medium-term efforts, which depend mainly on
*Corresponding author. Email: Ricardo.Mora@uclm.es
Biological Rhythm Research, 2014
Vol. 45, No. 1, 5160, http://dx.doi.org/10.1080/09291016.2013.797160
Ó2013 Taylor & Francis
Downloaded by [HINARI] at 12:39 13 December 2013
cardiorespiratory endurance (Atkinson et al. 2005; Simmonds et al. 2010). However,
circadian rhythm could also affect short-term competition events that rely on peaks of
muscle strength and power output (Souissi et al. 2007; Teo et al. 2011). For instance,
studies conducted with experienced swimmers have found a close association between
swimming performance and muscle power output, mainly when analyzing the ofcial
short-distance events (i.e. 25 m, 50 m, and 100 m) (Zampagni et al. 2008; Bishop et al.
2009; Potdevin et al. 2011; West et al. 2011). The few studies that have actually exam-
ined the effects of circadian rhythm on swimming performance have found a signicant
reduction from 1.2 to 3.5% in swimming performance when testing 50-m, 100-m, and
200-m freestyle in the early morning (i.e. 6:00 h10:00 h) in comparison to the results
of swimming the same distances in the evening (i.e. 17:00 h22:00 h) (Baxter & Reilly
1983; Deschodt & Arsac 2004; Kline et al. 2007; Martin et al. 2007). However, to our
knowledge, no study has examined the effects of circadian rhythm on the sprint swim-
ming performance (i.e. 25 m).
Based on the published high association between muscle peak power output and
short distance swimming performance (Zampagni et al. 2008; Bishop et al. 2009;
Potdevin et al. 2011; West et al. 2011) and knowing the deleterious effect that perform-
ing in the morning has upon neuromuscular performance (i.e. 3.07.5% reduction)
(Mora-Rodriguez et al. 2012), it is our hypothesis that all-out 25 m swimming perfor-
mance will be affected by circadian rhythm. Moreover, knowing the effects that time-
of-day has on 25 m swimming sprint could be useful to develop strategies that allow
coaches to avoid reduced performance during competition or to optimize the adaptations
during regular training. Therefore, the main aim of this study was to examine the circa-
dian rhythm effects on short-distance swimming performance (i.e. 25 m). A second
objective was to assess if muscle strength and power output of the upper and lower
body were affected similarly by time-of-day and its correlation with 25 m swimming
performance. We hypothesize a parallel decline in 25m swimming performance and
neuromuscular power in the morning, compared with the evening performance.
2. Methods
2.1. Subjects
Twelve well-trained junior swimmers (six male and six female in the age range of 17.1
± 2.7 years) volunteered to participate in this study. The physical and anthropometric
characteristics of the subjects are shown in Table 1. All the participants were experi-
enced swimmers with 8.8 ± 2.6 years of training career. However, none of them had
been involved in a resistance training program for more than six consecutive months
Table 1. Subjectscharacteristics.
All (n= 12) Male (n= 6) Female (n=6)
Age (years) 17.1 ± 2.7 18.3 ± 3.3 15.9 ± 1.5
Height (m) 1.72 ± 0.10 1.81 ± 0.06 1.64 ± 0.04
BM (kg) 65.6 ± 10.2 73.2 ± 7.6 58.0 ± 5.8
BMI (kg m
2
) 22.0 ± 1.7 22.4 ± 1.2 21.5 ± 2.1
Fat free mass (kg) 30.9 ± 6.8 36.6 ± 4.1 25.1 ± 2.4
Fat mass (%) 16.5 ± 6.8 11.8 ± 4.4 21.1 ± 5.6
Data are presented as mean ± SD.
52 J.G. Pallarés et al.
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per year. Therefore, they were all considered moderately resistance-trained individuals.
The subjects were informed in detail about the experimental procedures and the possible
risks and benets of the project. The study complied with the Declaration of Helsinki
and was approved by the Bioethics Commission of the University of Murcia. Written
informed consent was obtained from each athlete or from their parents or guardians
prior to participation.
2.2. Experimental design
In a random order, participants underwent the same battery of tests in two separated
days at different times of the day: (i) morning (10:00 h) and (ii) evening (18:00 h).
Trials were separated by 36 h in between. The experimental trials were designed to
evaluate the main effects of the time-of-day (morning vs. evening) on swimming and
neuromuscular performance. We selected those times of day for testing (i.e. 10:00 in
the morning and 18:00 in the evening) because they are common competition schedules
for this group of junior competitive swimmers. Participants underwent three familiariza-
tion sessions with the testing techniques and protocols performed in the actual study to
avoid the bias of progressive learning on test reliability. The last familiarization session,
performed in the morning (10:00 a.m.) of the second day prior to the beginning of each
experiment, included the determination of the following variables for each subject
(described later in detail): (i) the individual load (kg) that elicited a 1.00 m s
1
mean
propulsive velocity (MPV) in the free-weight bench press (BP) exercise and (ii) the
individual load (kg) corresponding to 75% of 1RM in BP exercise (Figure 1).
2.3. Experimental protocol
During the 48 h before testing, subjects refrained from physical activity other than that
required by the experimental trials. The day before the onset of the experiment, height
was measured to the nearest 0.5 cm during a maximal inhalation using a wall-mounted
stadiometer (Seca 202, Seca Ltd., Hamburg, Germany). Upon arrival to the testing facil-
ity, the subjectsbody weights were determined and body fat estimated in a fasted state
using a 4-contact electrode body composition bioimpedance analyzer (Tanita TBF-
300A, Tanita Corp., Tokyo, Japan). After a standardized warm-up that consisted of
5 min of pedaling a stationary bicycle at low intensity and 5 min of static stretches and
joint mobilization exercises, the subjects entered the laboratory to start the neuromuscu-
lar test battery assessments under controlled environmental conditions (i.e. 22 ± 1 °C
and 29 ± 3% relative humidity) and a strict-paced schedule (see Figure 1). These tests
consisted of the measurement of a standard countermovement vertical jump (CMJ)
height and the bar displacement velocity, for loads that elicit maximum muscle strength
(75% of 1 RM) and power output (1 m s
1
) adaptations in the BP exercise. The neuro-
muscular test battery ended with the assessment of peak muscle power output in a 10 s
crank-arm Wingate test. Finally, all the participants performed a swimming test, cover-
ing a distance of 25 m in freestyle, for which they were timed. The total time session of
each experimental protocol was 70 min.
2.4. Jumping test (CMJ)
Participants were instructed to complete a standard CMJ in which they squatted down
into a self-selected depth at/or below 100° knee exion, prior to explosively performing
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the concentric action. Participants were instructed to keep their hands on their hips at
all times and to maintain the same position at take-off and landing. Flight times were
measured using a vertical jump mat (Optojump, Microgate, Italy). The intraclass
coefcient correlation (ICC) and coefcient of variation (CV) were 0.94 and 3.3%,
respectively. The recorded height for this test was the average of three trials.
2.5. Maximum dynamic strength and maximal muscle power
During the last familiarization session, the individual loads that elicited a bar displace-
ment of 1.00 m s
1
and the load of 75% of 1RM for BP exercise were identied in a
graded loading test using a linear encoder and its associate software (T-Force System,
Ergotech, Murcia, Spain, 0.25% accuracy). Loads that allow bar displacement at a
velocity of 1.00 m s
1
are very close to those that maximize the mechanical power out-
put for isoinertial upper body multijoint resistance exercises (e.g. free-weight BP)
(Izquierdo et al. 2002; Sanchez-Medina & Gonzalez-Badillo 2011). In turn, 75% of 1
RM has been described as the minimal load that allows positive adaptations for maxi-
mum strength development in well resistance-trained athletes (American College of
Figure 1. Experimental protocol.
54 J.G. Pallarés et al.
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Sports 2009, Garcia-Pallares et al. 2010). After those loads were individually deter-
mined, changes in bar displacement velocity during the BP exercise as a consequence
of time-of-day (am vs. pm) were measured. Detailed description of the BP and SQ
execution technique, as well as the validity and reliability data of the dynamic measure-
ment system (ICC = 1.00; CV = 0.57%) have recently been reported (Sanchez-Medina &
Gonzalez-Badillo 2011).
2.6. Wingate test
The crank-arm Wingate test was performed on an adjustable, speed dependent arm
ergometer (Monark Cardio Rehab 891E, Varberg, Sweden) tted to the individual sub-
jects dimensions to align the mid-line of the sternum with the bottom bracket. Subjects
warmed up for 5 min with a frictional load of 2.0% of their individual body mass (BM)
using a self-selected cadence. During the warm-up period, two short sprints of 5-s dura-
tion were administered. Then, subjects were requested to crank at 60 rpm without load
(Reiser et al. 2000) at which point, a 5.0% BM resistance was dropped and a timer was
started. At this point subjects cranked as hard and fast as possible for the next 10 s. We
chose a 10-s test duration to avoid the fatiguing effects of performing a 30 s Wingate
test on the subsequent swimming bout. It has been reported that even 45 s Wingate test
is reliable for the measurement of anaerobic power in active university students (Balmer
et al. 2004). After completion of the test, subjects cycled against a light load for as long
as needed for recovery. Subjects were required to remain seated during the entire test.
Crank-arm peak power was identied as the highest cadence (in RPM) times the
frictional resistance in kilopond.
2.7. Swimming test
All participants performed a 25 m swimming test in a 25 m indoor swimming pool.
Swimmers performed a 400-m warm-up swim at 75% of their 400-m competition veloc-
ity, followed by a 5min passive resting period. After the warm-up, the subjects were
instructed to perform one all-out 25 m freestyle swimming test. The swimmers started
in a standardized position in the water, holding the backstroke handle with one hand
and having both feet on the wall. Both trials were held in the lane closest to the wall
(lane 6). Water temperature (27.5 ± 1.0 °C), air temperature (22.4 ± 0.8 °C, relative
humidity (43 ± 3%) and swimming pool lighting were held similar in both trials. All the
starts were on the initiative of the participants. Swim performance was assessed as the
time spent in covering 25 m which was recorded by two independent and experienced
coaches using handheld chronographs able to discriminate up to 1/100 of a second
(Namaste 988, Spain). The average time recording of the two timers was used for
subsequent analyses.
3. Statistical analysis
Data are presented as means and standard deviation (SD). ShapiroWilk test was used
to assess normal distribution of data. Neuromuscular differences between trials (am vs.
pm) were analyzed using one-way analysis of variance for repeated measurements. The
Greenhouse-Geisser adjustment for sphericity was calculated. After a signicant F test,
pairwise differences were identied using the Bonferroni signicance post hoc
procedure. Pearson correlation analysis was used to assess the associations between the
Biological Rhythm Research 55
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circadian rhythm declines on neuromuscular tests and 25-m swimming performance.
The signicance level was set at p6.05. Cohens formula for effect size (ES) was used
and the results were based on the following criteria: >0.70 large effect; 0.300.69
moderate effect; 60.30 small effect (Cohen 1988).
4. Results
4.1. Countermovement jump height and velocity against loads for maximum
dynamic strength and muscle power adaptations
The CMJ height was signicantly higher during the evening session (pm) when com-
pared to the morning (am) (4.3%; p= 0.02; ES = 0.65) (Figure 2(C)). Likewise, velocity
for maximal power (i.e. load that allow 1 m·s
1
) and maximum strength loads (i.e. load
of 75% 1RM) in BP exercise were signicantly greater in the pm protocol when
compared to the am (5.1%, p= 0.00, ES = 2.10; 3.6%, p= 0.04, ES = 1.87; respectively;
Figure 2(A) and (B)).
4.2. Wingate and swimming test
The crank-arm Wingate peak power recorded in the evening (pm) was 3.2% higher
without reaching signicance (p= 0.08, ES = 0.37) when compared to the morning
values (am) (Figure 2(D)). The time spent to cover 25 m freestyle swimming was
Figure 2. Time-of-day effects on velocity for (A) maximal power and (B) maximum strength
loads in BP, jump height (C) and crank-arm Wingate peak power output (D). Data are means
± SD.
Signicant differences compared to the am values. p60.05.
56 J.G. Pallarés et al.
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signicantly lower in the pm protocol (13.4 ± 0.3s) compared to the am (13.7 ± 0.3s)
(1.8%, p= 0.01, ES = 0.72). Ten out of the 12 swimmers improved their 25 m swimming
times in the pm trial while two of them did not respond to time-of-day effect (Figure 3).
5. Discussion
This study examines the effects of time-of-day on shortest ofcial swimming distance
(i.e. 25 m freestyle) and neuromuscular performance of young well-trained swimmers at
two times of the day that t with their habitual training and competition schedules (i.e.
10 am and 18 pm). The novel nding is that the time to complete one all-out 25 m
freestyle swim was signicantly longer (1.8%; p= 0.01) in the morning trial (10:00 h)
compared to the evening (18:00 h). Likewise, neuromuscular performance of upper (BP)
and lower body (countermovement jump) musculature showed signicant performance
decline in the morning when compared to the evening (3.65.1%). This ndings
corroborate results in endurance-trained and active subjects, where time-of-day effects
on neuromuscular performance were tested using either dynamic isoinertial contraction
(Mora-Rodriguez et al. 2012) or isometric and isokinetic maximal voluntary contrac-
tions (Gauthier et al. 2001; Racinais et al. 2005). However, to our knowledge we are
rst to test in the same group of athletes, the effects of time-of-day in an unspecic
power task that involve a single all-out movement (i.e. BP of counter movement jump)
in a 10-s arm cycling task that is somehow more specic to swimming, and nally in
25 m swimming performance.
Only a few studies have actually examined the time-of-day effects on swimming
performance in well and highly trained athletes (Baxter & Reilly 1983; Deschodt &
Arsac 2004; Kline et al. 2007; Martin et al. 2007). On the distances of 50 m, 100 m,
and 200 m, these authors have reported a maximum time-of-day performance decline of
2.53.6% which is slightly higher than the decline presently found for the 25 m free-
style distance (i.e. 1.7%). The differences in the daily uctuation in motor performance
between studies may be related to the specic time of day chosen to test. We tested
swimmers with 8 h separation between trials (i.e. 10:00 h vs. 18:00 h) while larger
differences in performance have been reported if trials are separated further away.
Baxter and Reilly (1983) used a repeated measures study on well-trained swimmers in
Figure 3. Time-of-day effects on swimming performance. Data are means ± SD.
Signicant
differences compared to the pm values. p60.05.
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the 100-m distance at 5 different circadian times (i.e. 6:30, 9:00, 13:30, 17:00, and
22:00 h). They detected the largest performance difference (3.5%) between 22:00 h (best
result) and 6:30 h (worst result). Similarly, Kline et al. (2007) in a study designed to
examine the circadian rhythm effects on the 200-m swimming performance addressed 8
different circadian times (i.e. 2:00, 5:00, 8:00, 11:00, 14:00, 17:00, 20:00, and 23:00 h)
and reported the largest performance uctuation (3.4%) between 23:00 and 5:00 h (i.e.
worst performance). Of note in both studies, the performance differences reported
between 10:00 h am and 18:00 h pm is very similar to ours (i.e. 1.02.0%)
To the best of our knowledge we are rst to correlate the effects of time-of-day on
neuromuscular power in the upper and lower body musculature with performance in the
shortest-distance swimming event (i.e. 25 m freestyle). It was our hypothesis that upper
and lower neuromuscular force would be intimately related to performance in this very
short swimming distance (i.e. 25 m). We expected associations much higher than with
longer swimming distances where variables dependent on swimming technique (e.g.
stroke rate and stroke length) are more relevant (Martin et al. 2007). However, we have
found that associations between pm and am on neuromuscular tests and 25 m swimming
performance were not high, and only one correlation approached signicance without
reach it (swimming vs. BP at a load of 1 m s
1
;r= 0.44; p= 0.08). The magnitude of
the decline in BP maximal movement velocity at 1 m s
1
in the am was around 5.1%
while swimming performance decreased by only 1.7% which is one third of the decline
in BP performance. Thus, it seems that up to two thirds of the decline in upper body
peak power could be compensated during 25 m freestyle where 1215 complete arm
stroke cycles are executed in around 13 s. The lack of stronger association suggests that
factors like muscle endurance or swimming technique also play an important role in
25 m swimming performance.
The association between the decline in am to pm in swimming time to complete
25 m freestyle and the decline in pm to am in CMJ height (a surrogate of leg power)
was low (i.e. r= 0.12, p= 0.70). Other authors have reported that the CMJ height is
highly correlated with 15-m swimming performance when starting from a block start
(West et al. 2011). In our study, we measure the time-of-day effects in the jumping abil-
ity of swimmers and our results are in line with those reported by Teo et al. (2011) and
Racinais et al. (2004) on college students. However, we found a poor correlation
between the reductions in swimming performance between am and pm and the reduc-
tions in jumping power. This could be due to the fact that our swimmers did not start
from the block but from the water and thus leg extension peak power was probably not
possible to reach due to water resistance. We did not measure time to complete half a
swimming pool lap (12.5 m) and therefore it is possible that a stronger correlation may
have been found with that intermediate time.
Crank-arm peak power also seemed to be under circadian inuence as the other
neuromuscular variables, but the effects did not reach statistical differences. The am
and pm differences (3.7%, p= 0.10) are lower than those described for well-trained
swimmers by Deschodt and Arsac (Deschodt and Arsac 2004) using leg cycling
Wingate test. These authors reported a 7.8% enhancement in peak power during pm in
comparison to am. However, other researchers that have evaluated the circadian rhythm
effects on the lower-body Wingate test on experienced athletes, have reported differ-
ences similar to ours between am and pm protocols (i.e. 2.55.7%) (Souissi et al. 2010;
Chtourou et al. 2011). We contend that our data on crank- arm peak power is more spe-
cic to swimming than leg cycling peak power and thus more applicable to swimming.
However, we recognize that more studies with a larger number of subjects are needed
58 J.G. Pallarés et al.
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to discard or accept an association between crank-arm cycling and swimming
performance.
In conclusion, time-of-day signicantly affects 25 m freestyle swimming perfor-
mance in conjunction with neuromuscular peak performance (i.e. power or maximal
force in the upper and lower body musculature) under climate controlled conditions in
junior competitive swimmers with signicant reductions in morning compared to the
evening. Coaches and swimmers should expect an average of 2% reduction in 25 m
freestyle sprint performance in the morning with some swimmers reducing performance
upto 5%, while much fewer having no effect on their performance (18% in our case).
These ndings highlight the need to adequate swimming training schedules of sprinting
swimmers to reduce the morning effects on their performance.
References
Atkinson G, Reilly T. 1996. Circadian variation in sports performance. Sports Med. 21:292312.
Atkinson G, Todd C, Reilly T, Waterhouse J. 2005. Diurnal variation in cycling performance:
inuence of warm-up. J Sports Sci. 23:321329.
Balmer J, Bird SR, Davison RCR, Doherty M, Smith PM. 2004. Mechanically braked Wingate
powers: agreement between SRM, corrected and conventional methods of measurement. J
Sports Sci. 22:661667.
Baxter C, Reilly T. 1983. Inuence of time of day on all-out swimming. Br J Sports Med.
17:122127.
Bishop DC, Smith RJ, Smith MF, Rigby HE. 2009. Effect of plyometric training on swimming
block start performance in adolescents. J Strength Cond Res. 23:21372143.
Chtourou H, Zarrouk N, Chaouachi A, Dogui M, Behm DG, Chamari K, Hug F, Souissi N. 2011.
Diurnal variation in Wingate-test performance and associated electromyographic parameters.
Chronobiol Int. 28:706713.
Cohen J. 1988. Statistical power analysis for the behavioral sciences. Hillsdale: Lawrence
Erlbaum.
American College of Sports M. 2009. American college of sports medicine position stand.
Progression models in resistance training for healthy adults. Med Sci sports exerc. 41:687
708.
Decostre V, Bianco P, Lombardi V, Piazzesi G. 2005. Effect of temperature on the working stroke
of muscle myosin. Proc Nat Acad Sci USA. 102:1392713932.
Deschodt VJ, Arsac LM. 2004. Morning vs. evening maximal cycle power and technical swim-
ming ability. J Strength Cond Res. 18:149154.
Garcia-Pallares J, Sanchez-Medina L, Esteban Perez C, Izquierdo-Gabarren M, Izquierdo M.
2010. Physiological effects of tapering and detraining in world-class kayakers. Med Sci Sports
Exerc. 42:12091214.
Gauthier A, Davenne D, Martin A, Van Hoecke J. 2001. Time of day effects on isometric
and isokinetic torque developed during elbow exion in humans. Eur J Appl Physiol.
84:249252.
Izquierdo M, Hakkinen K, Gonzalez-Badillo JJ, Ibanez J, Gonzalez-Badillo JJ, Ibanez J,
Gorostiaga EM. 2002. Effects of long-term training specicity on maximal strength and
power of the upper and lower extremities in athletes from different sports. Eur J Appl
Physiol. 87:264271.
Kline CE, Durstine JL, Davis JM, Moore TA, Devlin TM, Zielinski MR, Youngstedt SD. 2007.
Circadian variation in swim performance. J Appl Physiol. 102:641649.
Martin L, Nevill AM, Thompson KG. 2007. Diurnal variation in swim performance remains,
irrespective of training once or twice daily. Int J Sports Physiol Perform. 2:192200.
Mora-Rodriguez R, Garcia Pallares J, Lopez-Samanes A, Fernando Ortega J, Fernandez-Elias VE.
2012. Caffeine ingestion reverses the circadian rhythm effects on neuromuscular performance
in highly resistance-trained men. PLoS ONE. 7:e33807. Available from: http://www.ncbi.nlm.
nih.gov/pubmed/22496767.
Biological Rhythm Research 59
Downloaded by [HINARI] at 12:39 13 December 2013
Potdevin FJ, Alberty ME, Chevutschi A, Pelayo P, Sidney MC. 2011. Effects of a 6-week
plyometric training program on performances in pubescent swimmers. J Strength Cond Res.
25:8086.
Racinais S, Hue O, Blonc S. 2004. Time-of-day effects on anaerobic muscular power in a
moderately warm environment. Chronobiol Int. 21:485495.
Racinais S, Blonc S, Jonville S, Hue O. 2005. Time of day inuences the environmental effects
on muscle force and contractility. Med Sci Sports Exerc. 37:256261.
Reiser RF, Broker JP, Peterson ML. 2000. Inertial effects on mechanically braked Wingate power
calculations. Med Sci Sports Exerc. 32:16601664.
Sanchez-Medina L, Gonzalez.-Badillo JJ. 2011. Velocity loss as an indicator of neuromuscular
fatigue during resistance training. Med Sci Sports Exerc. 43:17251734.
Sedliak M, Finni T, Peltonen J, Hakkinen K. 2008. Effect of time-of-day-specic strength
training on maximum strength and EMG activity of the leg extensors in men. J Sports
Sci. 26:10051014.
Simmonds MJ, Minahan CL, Sabapathy S. 2010. Caffeine improves supramaximal cycling but
not the rate of anaerobic energy release. Eur J Appl Physiol. 109:287295.
Souissi N, Bessot N, Chamari K, Gauthier A, Sesbouee B, Davenne D. 2007. Effect of time
of day on aerobic contribution to the 30-s wingate test performance. Chronobiol Int.
24:739748.
Souissi N, Driss T, Chamari K, Vandewalle H, Davenne D, Gam A, Fillard J-R, Jousselin E.
2010. Diurnal variation in wingate test performances: inuence of active warm-up. Chronobi-
ol Int. 27:640652.
Starkie RL, Hargreaves M, Lambert DL, Proietto J, Febbraio MA. 1999. Effect of temperature on
muscle metabolism during submaximal exercise in humans. Exp Physiol. 84:775784.
Taylor K-L, Cronin J, Gill ND, Chapman DW, Sheppard J. 2010. Sources of variability in
iso-inertial jump assessments. Int J Sports Physiol Perform. 5:546558.
Teo W, McGuigan R, Newton MJ. 2011. The effects of circadian rhythmicity of salivary cortisol
and testosterone on maximal isometric force, maximal dynamic force, and power output. J
Strength Cond Res. 25:15381545.
West DJ, Owen NJ, Cunningham DJ, Cook CJ, Kilduff LP. 2011. Strength and power predictors
of swimming starts in international sprint swimmers. J Strength Cond Res. 25:950955.
Zampagni ML, Casino D, Benelli P, Visani A, Marcacci M, De Vito G. 2008. Anthropometric
and strength variables to predict freestyle performance times in elite master swimmers. J
Strength Cond Res. 22:12981307.
60 J.G. Pallarés et al.
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... Except for two studies 33,46 , better short-duration maximal exercise performances were found in the afternoon when single bouts of exercise were performed under neutral climate conditions. Short-duration maximal exercises that are influenced by the time of day include all-out swimming trials [47][48][49] , tennis services 37,40 , all-out cycl ing 13,23,24,27,28,35,36,38,42,43,[50][51][52][53][54] , maximal jumps 2,23,36,38,[40][41][42]46,49,[55][56][57] , repeated sprint ability 2,33,44,46,56,[58][59][60][61][62] , one repetition maximum (1RM) assessments [63][64][65][66] as well as other force-velocity based tests 35,40,49,54,62,63,67 . ...
... Except for two studies 33,46 , better short-duration maximal exercise performances were found in the afternoon when single bouts of exercise were performed under neutral climate conditions. Short-duration maximal exercises that are influenced by the time of day include all-out swimming trials [47][48][49] , tennis services 37,40 , all-out cycl ing 13,23,24,27,28,35,36,38,42,43,[50][51][52][53][54] , maximal jumps 2,23,36,38,[40][41][42]46,49,[55][56][57] , repeated sprint ability 2,33,44,46,56,[58][59][60][61][62] , one repetition maximum (1RM) assessments [63][64][65][66] as well as other force-velocity based tests 35,40,49,54,62,63,67 . ...
... Except for two studies 33,46 , better short-duration maximal exercise performances were found in the afternoon when single bouts of exercise were performed under neutral climate conditions. Short-duration maximal exercises that are influenced by the time of day include all-out swimming trials [47][48][49] , tennis services 37,40 , all-out cycl ing 13,23,24,27,28,35,36,38,42,43,[50][51][52][53][54] , maximal jumps 2,23,36,38,[40][41][42]46,49,[55][56][57] , repeated sprint ability 2,33,44,46,56,[58][59][60][61][62] , one repetition maximum (1RM) assessments [63][64][65][66] as well as other force-velocity based tests 35,40,49,54,62,63,67 . ...
Article
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Time-of-day dependent fluctuations in exercise performance have been documented across different sports and seem to affect both endurance and resistance modes of exercise. Most of the studies published to date have shown that the performance in short-duration maximal exercises (i.e. less than 1 min - e.g. sprints, jumps, isometric contractions) exhibits diurnal fluctuations, peaking between 16:00 and 20:00 h. However, the time-of-day effects on short duration exercise performance may be minimized by the following factors: (1) short exposures to moderately warm and humid environments; (2) active warm-up protocols; (3) intermittent fasting conditions; (4) warming-up while listening to music; or (5) prolonged periods of training at a specific time of day. This suggests that short-duration maximal exercise performance throughout the day is controlled not only by body temperature, hormone levels, motivation and mood state but also by a versatile circadian system within skeletal muscle. The time of day at which short-duration maximal exercise is conducted represents an important variable for training prescription. However, the literature available to date lacks a specific review on this subject. Therefore, the present review aims to (1) elucidate time-of-day specific effects on short-duration maximal exercise performance and (2) discuss strategies to promote better performance in short-duration maximal exercises at different times of the day.
... Diurnal variations in exercise performance have been well documented in a variety of exercise modalities but findings have been inconsistent (Deschenes et al., 1998;Pallarés et al., 2014;Saygin et al., 2018;Zarrouk et al., 2012). Zarrouk et al. showed that peak power and total work during cycling sprints were significantly higher in evening times than in morning times (Zarrouk et al., 2012). ...
... Zarrouk et al. showed that peak power and total work during cycling sprints were significantly higher in evening times than in morning times (Zarrouk et al., 2012). Further supporting this, Pallares et al. showed bench-press strength and 25 m swimming time were higher later in the day than earlier in the day (Pallarés et al., 2014). However, others have reported that time of day has little to no impact on performance measures (Deschenes et al., 1998;Falgairette et al., 2003). ...
Article
Purpose: The purpose of this study was to investigate how time-of-day training preference influences resistance-exercise performance. Methods: Resistance trained males (n = 12) were recruited for this study. In a crossover, counterbalanced design, participants completed two separate bench-press exercise trials at different times of day: (a) morning (AM; 8:00 hr) and (b) evening (PM; 16:00 hr). Participants answered a questionnaire on time-of-day training preference and completed a preferred (PREF) and nonpreferred (NON-PREF) time-of-day trial. For each trial, motivation was measured using a visual analog scale prior to exercise. Participants completed 2 sets × 2 repetitions at 75% 1-RM with maximum explosiveness separated by 5 min of rest. Mean barbell velocity was measured using a linear position transducer. Participants then completed 1 set × repetitions to failure (RTF) at 75% 1-RM. Rate of perceived exertion (RPE) was measured immediately following exercise. Results: Regardless of preference, velocity (p = .025; effect size (ES) = 0.43) was higher during the PM versus AM trial. However, there were no significant differences in velocity (p = .368; ES = 0.37) between PREF and NON-PREF time of day. There were no significant differences for repetitions between PREF and NON-PREF times (p = .902; ES = 0.03). Motivation was higher in the PREF time versus NON-PREF (p = .015; ES = 0.68). Furthermore, RPE was significantly lower during the PREF time of day (p = .048; 0.55). Conclusions: Despite higher barbell velocity collectively at PM times, time-of-training preference did not largely influence resistance-exercise performance, while motivation is higher and RPE is lower during preferred times.
... There are conflicts results in these studies. Pallares et al., (2014) found that the elite young swimmers had a statistically significant 4.3% higher vertical jump height in the morning (10.00am) than in the evening (18.00pm). ...
... Grant and Glen (2018) showed that the different time period of the day did not have a statistically significant effect on 800 m swimming performance. The study was conducted by Pallares et al. (2014) on elite young swimmers, they determined no statistically significant difference between the peak power values measured after Wingate test in the morning (10.00) and evening (18.00) hours. ...
... In humans, resistance and short-duration maximal exercise performance are influenced by diurnal fluctuations in metabolism, observing peak of performance at the evening (i.e., 16:00-20:00 h) compared to morning schedules (i.e., 6:00-10:00 h) (Grgic et al. 2019;Mirizio et al. 2020;Pallares et al. 2014;Zarrouk et al. 2012) and effect that seem to occur locally in skeletal muscle nor affecting neural structures (Sedliak et al. 2008). Nonetheless, active warm-ups with or without music, exposures to warm and humid environments, fasting conditions or prolonged training periods at morning hours seem to minimize these time-of-day differences in muscle force and power production (Mirizio et al. 2020). ...
Article
This study aimed to determine if time-of-day could influence physical volleyball performance in females and to explore the relationship between chronotype and volleyball-specific performance. Fifteen young female athletes participated in a randomized counterbalanced trial, performing a neuromuscular test battery in the morning (9:00 h) and the evening (19:00 h) that consisted of volleyball standing spike, straight leg raise, dynamic balance, vertical jump, modified agility T-test and isometric handgrip tests. Chronotype was determined by the morningness-eveningness questionnaire. Compared to the morning, an increased performance was found in the standing spike (4.5%, p = .002, ES = 0.59), straight leg raise test (dominant-limb) (6.5%, p = .012, ES = 0.40), dynamic balance (non-dominant-limb) (5.0%, p = .010, ES = 0.57) and modified T-test (2.1%, p = .049, ES = 0.45) performance in the evening; while no statistical differences were reported in vertical jump tests or isometric handgrip strength. Moreover, no associations were found between chronotype and neuromuscular performance (r = −0.368–0.435, p = .052–0.439). Time-of-day affected spike ball velocity, flexibility in the dominant-limb, dynamic balance in the non-dominant-limb and agility tests. However, no association was reported among these improvements and the chronotype. Therefore, although the chronotype may not play critical role in volleyball-specific performance, evening training/matches schedules could benefit performance in semi-professional female volleyball players
... Three different randomized conditions were implemented throughout the study: a control condition (CON), where no exercise was performed nor caffeine ingested, and two priming exercise conditions. To avoid any effect of circadian rhythms on the variables analyzed, participants were scheduled at the same time in the three experimental conditions (Pallarés et al., 2013). One of the priming conditions consisted of carrying out the priming exercise without any subsequent caffeine intake (Priming). ...
Article
Full-text available
Purpose: Morning priming exercise and caffeine intake have been previously suggested as an effective strategy to increase within-day performance and readiness. However, the concurrent effect of both strategies is unknown. The present research aimed to map the within-day time course of recovery and performance of countermovement jump (CMJ) outcomes, kinetics, and strategy and readiness after priming alone and in combination with caffeine. Methods: Eleven participants performed a control, a priming exercise (Priming) and a priming with concurrent caffeine intake (PrimingCaf) in a double-blind randomized, crossover design. CMJ metrics were assessed before, post, and 2 h, 4 h, and 6 h after each condition while readiness was assessed at 6 h. Results: Perceived physical, mental performance capability and activation balance were higher at 6 h after Priming and PrimingCaf conditions. Immediate reductions in jump height (5.45 to 6.25%; p < .046), concentric peak velocity (2.40 to 2.59%; p < .041) and reactive strength index-modified (RSImod) (9.06 to 9.23% p < .051) after Priming and PrimingCaf were observed, being recovered at 2 h (p > .99). Concentric impulse was restored in PrimingCaf (p > .754; d = -0.03 to-0.08) despite lower concentric mean force/BM (p < .662; d = -0.18 to -0.26) as concentric duration was increased (p > .513; d = 0.15 to 0.21). Individual analysis revealed that some participants benefit from both strategies as they showed increases in jump height over the smallest worthwhile change while others did not. Conclusions: Psychological readiness was increased after both priming conditions at 6 h; however, it seems necessary to consider individual changes to achieve the positive effects of the priming or the priming in combination with caffeine on jumping outcomes.
... Pavlovic et al., (Pavlović et al., 2018) in support of our findings showed that jump heights followed by static stretching in warm-up were higher at the evening (18:00-19:30 h) compared to morning (08:00-09:30 h) in handball players. In another study used static stretching in warm-up showed that swimmers performed better in CMJ, 25m swimming time, maximal strength, and free weighted bench press in the evening (18:00 h) than morning (10:00 h) (Pallarés et al., 2014). During evening nerve conduction velocity, enzymatic activity, and elasticity of muscles enhance, and muscle viscosity decreases due to increase in body temperature (Behm & Chaouachi, 2011;Bernard, Giacomoni, Gavarry, Seymat, & Falgairette, 1998). ...
Article
Full-text available
The purpose of the study was to investigate the effect of static stretching on squat jump (SJ) and countermovement jump (CMJ) in diurnal variation. Fifty-three male collegiate athletes (age=21.9±2.6 years; height=179.7±8.1cm; body-mass=75.3±8.6kg; mean±SD) completed the SJ and CMJ tests either after static stretching or no stretching protocols at two times of the day (07:00h and 17:00h) in random order on non-consecutive days. After warming-up for 5 minutes with low-intensity jogging, participants walked for 2 minutes before performing one of the two stretching protocols (static stretching or no stretching) then 4-5 minutes of additional rest was given before SJ and CMJ performances were measured. Jump heights were analyzed using the two-way ANOVA with repeated measures (2[stretching]×2[time-of-day]). No stretching protocol caused better jump heights in both SJ and CMJ (p< .01). SJ heights were higher at 17:00 compared to 07:00 in both static stretching (8.8%) and no stretching (9.1%) protocols (p< .01). Similarly, CMJ heights were higher at 17:00 compared to 07:00 in both static stretching (10.6%) and no stretching (5.8%) protocols (p< .01). Static stretching adversely influenced jump heights both in the morning and evening. However, it caused less negative effect in the evening.
... Die Rolle des Biorhythmus im SchwimmsportDie Erkenntnisse der Studie von FACER-CHILDS und BRANDSTAETTER (2015) lassen sich natürlich eher auf Sportarten außerhalb des Wassers übertragen. Es existieren jedoch auch Studien, die die Auswirkungen des zirkadianen Rhythmus auf die schwimmspezische Leistungsfähigkeit beleuchtet haben(LOK et al. 2020, PALLARÉS et al. 2014, KLINE et al. 2007, ARNETT 2002, MARTIN & THOMPSON 2000, BAXTER & REILLY 1983). LOK et al. (2020) nutzten die Schwimmzeiten der letzten vier olympischen Spiele (von 2004 bis 2016) zur Bestimmung des Einflusses der Tageszeit unter maximalen Motivationsbedingungen. Die Daten derjenigen Athleten, die es bis ins Finale schafften (n=144, 72 Frauen), wurden berücksichtigt und für jeden individuellen Athleten normalisiert, basierend auf den durchschnittlichen Schwimmzeiten über die drei Wettkampftypen (Heats, Semifinals und Finals) für jede Disziplin, jede Distanz und jeden olympischen Austragungsort. ...
Conference Paper
Full-text available
Erörterung über die Relevanz des Biorhythmus für die sportliche Leistungsfähigkeit (insbesondere im Schwimmsport)
... Furthermore, it would be of interest to compare different chronotypes (Vitale and Weydahl 2017) and assess habitual training time (Rae et al. 2015), because different chronotypes may achieve their peak performance at different times of the day and habitually training at a certain time of the day may lead to a familiarization and influence the time of peak performance. Out of 11 published studies since 2013, 10 had ≤4 measurement points (Ammar et al. 2015;Bowdle et al. 2016;Chtourou et al. 2013;Hatfield et al. 2016;Heishman et al. 2017;Küüsmaa et al. 2015;Pallarés et al. 2014;Robinson et al. 2013;Sinclair et al. 2013;West et al. 2014), and one had insufficient regeneration time between the tests (Buckner et al. 2016). Forty-one studies have yet been published so far with inconclusive results regarding the fact if there is a time of peak performance or not. ...
Article
Time-of-day effects in strength performance have been extensively investigated due to their relevance in competitive sports. However, most studies use large measurement intervals making it difficult to monitor potential performance changes throughout the day. Furthermore, previous studies have exclusively focused on how the time of day affects strength on a group level and ignored the individual differences in the times of peak performance. Therefore, the main purpose of this study was to investigate the diurnal and day-to-day variations in isometric and isokinetic leg, arm and trunk strength over six different times of the day. Following a familiarization test, 19 trained males (age: 24.1 ± 2.5 years) performed isometric and isokinetic strength assessments at six different times of the day (7:00, 10:00, 13:00, 16:00, 19:00, and 21:00) with an isokinetic dynamometer. An eighth test session was performed at the same time of the day as the seventh test session to investigate the day-to-day variations and the difference between diurnal and day-to-day variations were compared. All tests were separated by at least 48 h. The start time for the first session was randomized. The mean maximum isometric leg strength was 5.85 ± 0.80 N.kg⁻¹ and 4.99 ± 0.78 N.kg⁻¹at the peak and at the nadir of the day, respectively. The mean difference (95% CI) was 0.86 ± 0.47 N.kg⁻¹ (0.62; 1.10) for the diurnal variation and 0.30 ± 0.42 N.kg⁻¹ (0.09; 0.52) for the day-to-day variation. The mean maximum isometric arm strength was 1.68 ± 0.33 N.kg⁻¹ at the peak and 1.46 ± 0.19 N.kg⁻¹ at the nadir of the day, respectively. The mean difference (95% CI) was 0.21 ± 0.16 N.kg⁻¹ (0.14; 0.29) for the diurnal variation and 0.06 ± 0.05 N.kg⁻¹ (0.03; 0.08) for the day-to-day variation. The linear mixed-effects model showed little evidence for differences in isometric leg strength between the different times of the day (all p-values >0.983). The present study demonstrated that diurnal variations in leg and arm strength are nearly three times higher than the day-to-day variations, but there was only little evidence for a time-of-day effect on a group level. The diurnal variations observed herein without time-of-day effects are suggestive that individuals achieve their peak performance at different times of the day. Therefore, performance tests should be carried out at the same time of the day to ensure comparability. Furthermore, depending on the difference between the time of competition and the time of peak performance, as well as the individual magnitude in diurnal variation, some athletes can have a clear disadvantage.Abbreviation: 95% CI, 95% confidence interval; SD, standard deviation; ICC, intraclass correlation coefficient.
Article
The aim of this study is to examine the daytime effects on flip turn performance [i.e., 3 m round trip time (3mRTT) as measure of turning performance] as well as global performance during a 50 m freestyle at maximal speed. Twelve college swimmers performed 3 × 50 m freestyle at maximum speed with a flip turn and glide in a 25 m pool in two experimental trials, one in the morning (08:00 h) and one in the evening (18:00 h). Kinematic and dynamic parameters of flip turn performance are analyzed using one underwater camera and a force platform recording wall force peak and time contact. Results showed that oral temperature is significantly higher (p < 0.001) in the evening than in the morning. Also, this study reported that daily variations have been observed for both, changes in swim performance and changes in (3mRTT). Thus, kinematic and dynamic flip turn variables associated with an improvement of freestyle swim performance. It is concluded that maximal swimming trials are performed better in the evening than in the morning, and that this might be linked to variations in oral temperature; also, might be explained by better flip turn performance at this time.
Thesis
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The doctoral thesis presented in this document is structured in three different parts. The first part of the work is composed of studies I and II, where the validation work of two different workload cycling tools, “drive indoor trainer Cycleops Hammer” and “PowerTap P1 Pedals Power Meter “, is detailed. In both articles, randomized and counterbalanced incremental workload tests (100-500 W) were performed, at 70, 85 and 100 rev·min-1 cadence, with sitting and standing pedalling in 3 different Hammer unit cadences. Then, the results are compared against the values measured by a professional SRM crankset. In general terms, no significant differences were detected between the Hammer devices and the SRM, while strong intraclass correlation coefficients were observed (≥0.996; p=0.001), with low bias (-5,5 a 3,8), and high values of absolute reproducibility (CV<1,2%, SEM<2,1). The PowerTap P1 pedals showed strong correlation coefficients in a seated position (rho ≥ 0.987). They underestimated the power output obtained in a directly proportional way to the cadence, with an average error of 1.2%, 2.7%, 3.5% for 70, 85 and 100 rev∙min-1. However, they showed high absolute reproducibility values (150-500 W, CV = 2.3%, SEM <1.0W). These results prove that both are valid and reproducible devices to measure the power output in cycling, although caution should be exercised in the interpretation of the results due to the slight underestimation. The second part of the thesis is devoted to the study III, where the time to exhaustion (TTE) at the workloads related to the main events of the aerobic and anaerobic pathway in cycling were analysed in duplicate in a randomized and counterbalanced manner (Lactic anaerobic capacity (WAnTmean), the workload that elicit VO2max -MAP-, Second Ventilatory Threshold (VT2) and at Maximal Lactate Steady State (MLSS). TTE values were 00:28±00:07, 03:27±00:40, 11:03±04:45 and 76:35±12:27 mm:ss, respectively. Moderate between-subject reproducibility values were found (CV=22.2%,19.3%;43.1% and 16.3%), although low within-subject variability was found (CV=7.6%,6.9%;7.0% y 5.4%). According to these results, the %MAP where the physiological events were found seems to be a useful covariable to predict each TTE for training or competing purposes. Finally, in the third part of the work, the results of studies IV y V have been included. The validity of two different methods to estimate the cyclists’ workload at MLSS was evaluated. The first method was a 20 min time trial test (20TT), while the second method was a one-day incremental protocol including 4 steps of 10 minutes (1day_MLSS). The 20TT test absolute reproducibility, performed in duplicate, was very high (CV = -0.3±2.2%, ICC = 0.966, bias = 0.7±6.3 W). 95% of the mean 20TT workload overestimated the MLSS (bias 12.3±6.1W). In contrast, 91% of 20TT showed an accurate prediction of MLSS (bias 1.2±6.1 W), although the regression equation "MLSS (W) = 0.7489 * 20TT (W) + 43.203" showed even a better MLSS estimates (bias 0.1±5.0 W). Related to the 1day_MLSS test, the physiological steady state was determined as the highest workload that could be maintained with a [Lact] rise lower than 1mmol·L-1. No significant differences were detected between the MLSS (247±22 W) and the main construct of the test (DIF_10to10) (245±23 W), where the difference of [Lact] between minute 10 of two consecutive steps were considered, with high correlations (ICC = 0.960), low bias (2.2W), as well as high within-subject reliability (ICC = 0.846, CV = 0.4%, Bias = 2.2±6.4W). Both methods were revealed as valid predictors of the MLSS, significantly reducing the requirements needed to individually determine this specific intensity.
Article
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To investigate whether caffeine ingestion counteracts the morning reduction in neuromuscular performance associated with the circadian rhythm pattern. Twelve highly resistance-trained men underwent a battery of neuromuscular tests under three different conditions; i) morning (10:00 a.m.) with caffeine ingestion (i.e., 3 mg kg(-1); AM(CAFF) trial); ii) morning (10:00 a.m.) with placebo ingestion (AM(PLAC) trial); and iii) afternoon (18:00 p.m.) with placebo ingestion (PM(PLAC) trial). A randomized, double-blind, crossover, placebo controlled experimental design was used, with all subjects serving as their own controls. The neuromuscular test battery consisted in the measurement of bar displacement velocity during free-weight full-squat (SQ) and bench press (BP) exercises against loads that elicit maximum strength (75% 1RM load) and muscle power adaptations (1 m s(-1) load). Isometric maximum voluntary contraction (MVC(LEG)) and isometric electrically evoked strength of the right knee (EVOK(LEG)) were measured to identify caffeine's action mechanisms. Steroid hormone levels (serum testosterone, cortisol and growth hormone) were evaluated at the beginning of each trial (PRE). In addition, plasma norepinephrine (NE) and epinephrine were measured PRE and at the end of each trial following a standardized intense (85% 1RM) 6 repetitions bout of SQ (POST). In the PM(PLAC) trial, dynamic muscle strength and power output were significantly enhanced compared with AM(PLAC) treatment (3.0%-7.5%; p≤0.05). During AM(CAFF) trial, muscle strength and power output increased above AM(PLAC) levels (4.6%-5.7%; p≤0.05) except for BP velocity with 1 m s(-1) load (p = 0.06). During AM(CAFF), EVOK(LEG) and NE (a surrogate of maximal muscle sympathetic nerve activation) were increased above AM(PLAC) trial (14.6% and 96.8% respectively; p≤0.05). These results indicate that caffeine ingestion reverses the morning neuromuscular declines in highly resistance-trained men, raising performance to the levels of the afternoon trial. Our electrical stimulation data, along with the NE values, suggest that caffeine increases neuromuscular performance having a direct effect in the muscle.
Article
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The present study was designed to evaluate time-of-day effects on electromyographic (EMG) activity changes during a short-term intense cycling exercise. In a randomized order, 22 male subjects were asked to perform a 30-s Wingate test against a constant braking load of 0.087 kg·kg(-1) body mass during two experimental sessions, which were set up either at 07:00 or 17:00 h. During the test, peak power (P(peak)), mean power (P(mean)), fatigue index (FI; % of decrease in power output throughout the 30 s), and evolution of power output (5-s span) throughout the exercise were analyzed. Surface EMG activity was recorded in both the vastus lateralis and vastus medialis muscles throughout the test and analyzed over a 5-s span. The root mean square (RMS) and mean power frequency (MPF) of EMG were calculated. Neuromuscular efficiency (NME) was estimated from the ratio of power to RMS. Resting core temperature, P(peak), P(mean), and FI were significantly higher (p < .05) in the evening than morning test (e.g., P(peak): 11.6 ± 0.8 vs. 11.9 ± 1 W·kg(-1)). The results showed that power output decreased following two phases. During the first phase (first 20s), power output decreased rapidly and values were higher (p < .05) in the evening than in the morning. During the second phase (last 10s), power decreased slightly and appeared independent of the time of day of testing. This power output decrease was paralleled by evolution of the MPF and NME. During the first phase, NME and MPF were higher (p < .05) in the evening. During the second phase, NME and MPF were independent of time of day. In addition, no significant differences were noticed between 7:00 and 17:00 h for EMG RMS during the whole 30 s. Taken together, these results suggest that peripheral mechanisms (i.e., muscle power and fatigue) are more likely the cause of the diurnal variation of the Wingate-test performance rather than central mechanisms.
Article
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This investigation aimed to quantify the typical variation for kinetic and kinematic variables measured during loaded jump squats. Thirteen professional athletes performed six maximal effort countermovement jumps on four occasions. Testing occurred over 2 d, twice per day (8 AM and 2 PM) separated by 7 d, with the same procedures replicated on each occasion. Jump height, peak power (PP), relative peak power (RPP), mean power (MP), peak velocity (PV), peak force (PF), mean force (MF), and peak rate of force development (RFD) measurements were obtained from a linear optical encoder attached to a 40 kg barbell. A diurnal variation in performance was observed with afternoon values displaying an average increase of 1.5-5.6% for PP, RPP, MP, PV, PF, and MF when compared with morning values (effect sizes ranging from 0.2-0.5). Day to day reliability was estimated by comparing the morning trials (AM reliability) and the afternoon trials (PM reliability). In both AM and PM conditions, all variables except RFD demonstrated coefficients of variations ranging between 0.8-6.2%. However, for a number of variables (RPP, MP, PV and height), AM reliability was substantially better than PM. PF and MF were the only variables to exhibit a coefficient of variation less than the smallest worthwhile change in both conditions. Results suggest that power output and associated variables exhibit a diurnal rhythm, with improved performance in the afternoon. Morning testing may be preferable when practitioners are seeking to conduct regular monitoring of an athlete's performance due to smaller variability.
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This study examined in pubescent swimmers the effects on front crawl performances of a 6-week plyometric training (PT) in addition to the habitual swimming program. Swimmers were assigned to a control group (n = 11, age: 14.1 ± 0.2 years; G(CONT)) and a combined swimming and plyometric group (n = 12, age: 14.3 ± 0.2 years; GSP), both groups swimming 5.5 h · wk(-1) during a 6-week preseason training block. In the GSP, PT consisted of long, lateral high and depth jumps before swimming training 2 times per week. Pre and posttests were performed by jump tests (squat jump [SJ], countermovement jump [CMJ]) and swim tests: a gliding task, 400- and 50-m front crawl with a diving start (V400 and V50, m · s(-1)), and 2 tests with a water start without push-off on the wall (25 m in front crawl and 25 m only with kicks). Results showed improvement only for GSP for jump tests (Δ = 4.67 ± 3.49 cm; Δ = 3.24 ± 3.17 cm; for CMJ and SJ, respectively; p < 0.05) and front crawl tests (Δ = 0.04 ± 0.04 m · s(-1); Δ = 0.04 ± 0.05 m · s(-1); for V50 and V400, respectively; p < 0.05). Significant correlations were found for GSP between improvements in SJ and V50 (R = 0.73, p < 0.05). Results suggested a positive effect of PT on specific swimming tasks such as dive or turn but not in kicking propulsion. Because of the practical setup of the PT and the relevancy of successful starts and turns in swimming performances, it is strongly suggested to incorporate PT in pubescent swimmers' training and control it by jump performances.
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The study investigated the effects of circadian rhythm of cortisol (C) and testosterone (T) on maximal force production (Fpeak) and power output (Ppeak). Twenty male university students (mean age = 23.8 ± 3.6 years, height = 177.5 ± 6.4 cm, weight = 78.9 ± 11.2 kg) performed 4 time-of-day testing sessions consisting of countermovement jumps (CMJs), squat jumps (SJ), isometric midthigh pulls (IMTPs), and a 1-repetition maximum (1RM) squat. Saliva samples were collected at 0800, 1200, 1600, and 2000 hours to assess T and C levels on each testing day. Session rate-of-perceived exertion (RPE) scores were collected after each session. The results showed that Fpeak and Ppeak presented a clear circadian rhythm in CMJ and IMTP but not in SJ. One repetition maximum squat did not display a clear circadian rhythm. Session RPE scores collected at 0800 and 2000 hours were significantly (p ≤ 0.05) higher than those obtained at 1200 and 1600 hours. Salivary T and C displayed a clear circadian rhythm with highest values at 0800 hours and lowest at 2000 hours; however, no significant correlation was found between T and C with Fpeak and Ppeak. A very strong correlation was found between Taural with Fpeak of CMJ and IMTP and Ppeak of CMJ (r = 0.86, r = 0.84 and r = 0.8, p ≤ 0.001). The study showed the existence of a circadian rhythm in Fpeak and Ppeak in CMJ and IMTP. The evidence suggests that strength and power training or testing should be scheduled later during the day. The use of Taural seemed to be a more effective indicator of physical performance than hormonal measures, and the use of session RPE should also be closely monitored because it may present a circadian rhythm.