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Citation: Bougrine, H.; Salem, A.;
Nasser, N.; Ammar, A.; Chtourou, H.;
Souissi, N. Ramadan Fasting and
Short-Term Maximal Physical
Performance: Searching for Optimal
Timing of the Last Meal “Suhoor” in
Female Pre-University Handball
Players. Eur. J. Investig. Health
Psychol. Educ. 2023,13, 2160–2178.
https://doi.org/10.3390/
ejihpe13100152
Academic Editors: María del Mar
Molero Jurado, JoséCarmelo Adsuar,
Roxana Paola Palacios Cartagena,
Carmen Galán Arroyo and
María Mendoza Muñoz
Received: 30 August 2023
Revised: 2 October 2023
Accepted: 6 October 2023
Published: 7 October 2023
Copyright: © 2023 by the authors.
Licensee MDPI, Basel, Switzerland.
This article is an open access article
distributed under the terms and
conditions of the Creative Commons
Attribution (CC BY) license (https://
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4.0/).
Article
Ramadan Fasting and Short-Term Maximal Physical
Performance: Searching for Optimal Timing of the Last Meal
“Suhoor” in Female Pre-University Handball Players
Houda Bougrine 1,2, Atef Salem 1,3,4, Nidhal Nasser 1,3, Achraf Ammar 3,4,5,6,* , Hamdi Chtourou 1,3
and Nizar Souissi 1,7
1Physical Activity Research Unit, Sport and Health (UR18JS01), National Observatory of Sports,
Tunis 1003, Tunisia; houdabougrine@live.fr (H.B.); nidhalnasser@issepsf.u-sfax.tn (N.N.);
h_chtourou@yahoo.fr (H.C.); n_souissi@yahoo.fr (N.S.)
2High Institute of Sport and Physical Education Gafsa, Gafsa University, Gafsa 2100, Tunisia
3High Institute of Sport and Physical Education Sfax, University of Sfax, Sfax 3000, Tunisia
4Department of Training and Movement Science, Institute of Sport Science, Johannes Gutenberg-University
Mainz, 55099 Mainz, Germany
5Research Laboratory, Molecular Bases of Human Pathology, LR19ES13, Faculty of Medicine of Sfax,
University of Sfax, Sfax 3029, Tunisia
6Interdisciplinary Laboratory in Neurosciences, Physiology, and Psychology: Physical Activity, Health, and
Learning (LINP2), UFR STAPS (Faculty of Sport Sciences), UPL, Paris Nanterre University,
92000 Nanterre, France
7High Institute of Sport and Physical Education Ksar-Saïd, Manouba University, Mannouba 2010, Tunisia
*Correspondence: acammar@uni-mainz.de or ammar.achraf@ymail.com; Tel.: +49-15236403235
Abstract: Aiming to identify the ideal suhoor timing for maintaining optimal physical performance
and health indicators during Ramadan intermittent fasting, the present study compares the effects
of early vs. late Suhoor on short-term high-intensity physical exercise while controlling the body
mass index (BMI) oral temperature (OT), dietary intake, and sleep patterns. In a randomized
design, 19 female pre-university handball players (age: 16.8
±
0.4 y; height: 1.70
±
0.9 m; and body
mass: 61.5
±
6.9 kg) underwent two test sessions (at 08:00 a.m. and 05:00 p.m.) at four different
conditions: ten days prior to Ramadan (R
−
10), the final ten days of Ramadan (R) including both
Early Suhoor R(ES) and Late Suhoor R(LS) conditions, and the ten days immediately following
Ramadan (
R + 10
). A recovery period of at least 48 h has been set between successive test sessions
at each period. Outcome measures included the Countermovement Jumps Test (CMJ), Modified
Agility t-Test (MATT), Repeated Sprint Ability (RSA), and Rating of Perceived Exertion (RPE). The
Pittsburgh Sleep Quality Index (PSQI), OT, BMI, and daily diary intake were assessed across the three
periods. The total scores of PSQI decreased significantly during R and R + 10 compared to R
−
10.
When performed in the afternoon, CMJ, MATT, and RSA performance decreased significantly at R(ES)
and R(LS) conditions compared to R
−
10. However, these performances decreased only after R(ES)
when performed in the morning. Furthermore, performances were lower during R(ES) compared
to R(LS) in the afternoon for all tests and the morning for MATT and RSA tests. These findings
support prior research showing a deterioration of physical performance during Ramadan fasting and
indicate a more pronounced impact following early Suhoor condition. Therefore, consuming a late
suhoor, closer to pre-dawn time, could be suggested as an effective strategy to minimize physical
performance decline during short-term high-intensity exercise.
Keywords:
ramadan intermittent fasting; suhoor; nutrient timing; sleep patterns; physical
performance
;
female athletes
1. Introduction
While ball team sports involve diverse technical, physiological, and cognitive per-
formances that are influenced by various factors, there are common objectives related
Eur. J. Investig. Health Psychol. Educ. 2023,13, 2160–2178. https://doi.org/10.3390/ejihpe13100152 https://www.mdpi.com/journal/ejihpe
Eur. J. Investig. Health Psychol. Educ. 2023,13 2161
to nutrition in order to perform optimally in major competitions, adapt to training, and
minimize injury and illness risks. Specific recommendations can be made to determine the
appropriate quality, quantity, and timing of food and drink intake to improve overall well-
being and athletic performance in various training and competition contexts. While the
relationship between different nutrient intakes and athletic achievement has long intrigued
researchers for an extended period, the temporal aspect of nutrient intake is a relatively
new area of study that has gained increasing interest in recent years [
1
,
2
]. Recent data
revealed that the timing, amount, and composition of nutrients can have a major impact on
optimizing an athlete’s endurance, strength, and recovery [
3
,
4
]. On the other hand, success
in competition for limited amounts of food and/or beverages for different periods of time
has remained an important issue for athletic performance.
In sports, Ramadan Intermittent Fasting (RIF) represents one of these conditions, as it
is a unique mode of fasting requiring continuous daily fasting of food and drink, including
water, for 12 to 18 h (depending on geographical location, the season of the year, and solar
calendar dates) over 29–30 days [
5
]. During Ramadan month, Muslims often eat a couple
of meals per day: one at the completion of their daily fast at sunset, known as iftar, and the
second before the break of dawn, known as suhoor [
5
]. The increased demands of modern
sports, linked with the rise of the number of Muslim athletes in Western (non-Muslim)
countries, have compelled sports experts to investigate the impact of RIF on physical
performance within this time frame. Consequently, studies surrounding this topic could
aid Muslim athletes and their coaches in strategizing competitions and optimizing their
performance during this period.
Indeed, this prolonged fasting from food and fluids (from dawn and sunset), accom-
panied by a shift in meal timing to the hours of darkness, may affect the biological clock [
6
],
nighttime sleep quality [
7
], and athletic performance [
8
]. Evidence about changes in food
intake and sleeping habits during this month has incited several researchers to explore the
effect of RIF on athletes’ performance, though the evidence remains inconclusive, particu-
larly with regard to short-term high-intensity exercises. In fact, previous findings reported
a decrease in short-term high–intensity during RIF in agility and jumping performance [
5
,
9
]
and repeated sprints [
10
,
11
]. Contrary to these studies, some other studies did not observe
the negative impacts of RIF on jumping performance [
12
,
13
], agility [
13
,
14
], or repeated
sprints [15].
To explain this decline in performance, researchers have also explored the effects
of RIF on sleep quality and quantity [
5
,
7
] and dairy intake [
5
,
9
]. Apart from affecting
performance, the daily caloric quantity intake was suggested as a factor contributing to
decreased performance during fasting by some studies [
16
,
17
]. In contrast, several studies
revealed no significant differences in this parameter during the RIF month compared to
before Ramadan [
5
,
18
]. Meal time, however, has recently been shown to affect energy
balance [
19
,
20
]. Nevertheless, the caloric restriction during RIF, fewer daily meals (only
two meals), and dietary changes may lead to critical daytime dehydration [
21
], lower total
protein synthesis and energy availability [
22
,
23
], decrease the availability and use of energy
substrates, as well as establish alterations in hormonal and metabolic responses in combi-
nation with dehydration [
24
,
25
]. Surprisingly, to date, no study has explored the effects
of the timing of the last meal (suhoor) before fasting on athletic performance, especially
when the fasting hours are prolonged. While research on the timing of meals during RIF is
lacking, current data suggests that nutritional factors, such as energy intake, macronutrient
composition, and meal timing, could potentially impact athletes’ sleep patterns [
26
]. Hence,
athletic performance could be impaired by a shifted circadian rhythm, altered timing and
frequency of meal consumption, reduced calorie and carbohydrate intake, altered metabolic
pattern, irregular sleeping duration and timing, and dehydration [
22
]. Interestingly, calorie
restriction has been associated with prolonged sleep onset and reduced slow-wave sleep in
overweight women [
27
]. Given that Suhoor timing is influenced by individual preferences
and lifestyles during RIF, and considering that circadian rhythms can impact the body’s
Eur. J. Investig. Health Psychol. Educ. 2023,13 2162
response to food and exercise at varying times, it is essential to take these rhythms into
account when determining the ideal timing for Suhoor in relation to physical performance.
On the other hand, although half of the sport’s participants are female, less is known
about nutrition to promote both health and performance tailored to the unique physiological
characteristics of female athletes [
28
]. While athletes require a well-balanced and sufficient
nutrient intake to support their training and performance, the optimal timing of nutrient
intake in RIF for athletes is not well-defined and requires further investigation. Although
the importance of nutrient timing is increasingly recognized, current recommendations
are often based on limited evidence and are not standardized, leading to confusion among
athletes and coaches, which may lead to suboptimal performance and an increased risk of
injury [29]. Thus, specific nutrient timing guidelines during RIF are needed.
With this background of evidence, to our knowledge, there is no evidence that the
late suhoor intake before starting the fast will have a more significant effect on physical
performance. Therefore, the main aim of this investigation was to examine the effect of the
timing of the last meal (suhoor) on different aspects of short-term high-intensity perfor-
mance during morning and afternoon exercises in adolescent female handball players and
provide insights into how athletes can optimize Ramadan performance by manipulating
their mealtimes. It was hypothesized that (i) RIF would negatively impact short-term
high-intensity physical performance primarily in the afternoon rather than the morning,
and (ii) late Suhoor intake may mitigate the decline in short-term high-intensity exercise
performance caused by RIF when compared to an early Suhoor intake.
2. Materials and Methods
2.1. Participants
To allow for an estimated 15% dropout rate at follow-up, 19 pre-university female
handball players from the first Tunisian league team were voluntarily involved in this
study, whose average age, height, weight, and IMC were 16.8
±
0.4 years; 1.70
±
0.9 m;
61.5
±
6.9 kg; and 21.6
±
1.8 kg/m
2
, respectively. All players gave their written consent
(free and informed) after being informed in detail about the experimental procedures and
their constraints before participating, and they could withdraw from the study at any time.
Since all our participants are under the age of 18, parental written approval was required.
All coaches have also given their official consent. The Local Research Committee granted
ethical permission for the protocol and experimental procedure. All the study’s protocols
adhere to the 1975 Declaration of Helsinki’s ethical standards [30].
They were in and regularly engaged for 2 h a day, 5 days a week, for at least
3 years. Prior to Ramadan, they established a set schedule for eating meals (breakfast
at
07:00 a.m. ±1:00 h
, lunch at 12:00 a.m.
±
1:00 h, and dinner at 08:00 p.m.
±
1:00 h) and
sleeping (sleeping between 10:30 p.m.
±
1:00 h and 07:00 a.m.
±
1:00 h) according to their
daily sleep-wake cycle. In order to guarantee homogeneity and reduce the dispersion of
circadian topology in the experimental populations, the players were selected according
to their answers to the Horne and Ostberg [
31
] self-evaluation questionnaire of the type
of sleep, which rates morningness and eveningness. Based on their answers to questions,
subjects who showed an extreme morning or evening type were disqualified. Instead, all
investigation participants were chronotypes of the “neither type”, with scores on the scale
ranging from 46 to 57.
All athletes had a typical sleep duration of 7.8
±
0.4 h in the month prior to the
experimental method, as measured by the Pittsburgh Sleep Quality Index (PSQI) [
32
].
Moreover, to ensure consistency and minimize the influence of the habitual timing of
suhoor among the participants in the study, subjects were chosen based on their responses
to the daily time of suhoor during the first 20 days of RIF. Participants who presented
extreme habitual times of suhoor (consumed at
≤
10:30
±
30 p.m. or
≥
03:30
±
30 a.m.) that
coincided with our two chosen times in our study were disqualified. Therefore, the study
included players with daily habitual timing suhoor at 01:30
±
60 a.m. The inclusion criteria
were as follows: (i) no history of major medical conditions, smoking, caffeine dependence,
Eur. J. Investig. Health Psychol. Educ. 2023,13 2163
or daily habitual napping; (ii) observing Ramadan for at least three years; (iii) not using
any form of contraception, including pills, patches, injections, implants, or intrauterine
devices; and/or had any menstrual or endocrine abnormalities in the previous six months.
All phases of the menstrual cycle of participants were assessed during all testing sessions
using a mobile application (MyCalendar
®
; Period Tracker) that identifies the main events
taking place throughout the menstruation cycle [
33
]. “Moreover, only players who had
not been previously affected by COVID-19 were recruited. This decision was made due
to concerns that the COVID-19 pandemic might have effects on athletes’ physical activity,
including lower sleep quality than recommended and higher insomnia symptoms, as well
as on their mental health and quality of life, such as a mismatch between circadian and
social clocks pre-lockdown [34].
2.2. Tool
For the experimental sessions, players reported to the course one hour before the
start of sessions for data collection, where the pre-experimental assessments, basic anthro-
pometry, and experimental trials were performed. During each experimental session, oral
temperature and anthropometric measurements were recorded at the beginning of each test
session. Body mass was measured using an electronic scale (Tanita, Tokyo, Japan). A digital
clinical thermometer (Omron, Paris, France; accuracy +0.05 ◦C) was inserted sublingually
for at least three minutes after a 10-min period of resting while seated in order to measure
the oral temperature. Following that, athletes performed a standardized warm-up (~10 min
including rest), which consisted of 3 min jogging (at 8–10 km
·
h
−1
). Jogging was followed
by 3 min of whole-body dynamic stretching, 2 min of sprint drills (ankling, high-knee,
backkick, and skipping), and 2 min of sprinting. Athletes then performed during each test
session in the same order: Countermovement Jumps test (CMJ), Modified Agility t-Test
(MATT), Repeated Sprint Ability (RSA), and Rating of Perceived Exertion (RPE). A 5-min
rest was taken between tests to ensure appropriate recovery. Moreover, the RPE was carried
out by having players respond verbally after each 25 m shuttle sprint in the RSA test.
Testing sessions were conducted at an indoor training facility with relatively similar
ambient temperatures (~25
◦
C, 28
◦
C, and 28
◦
C) and relative humidity (~54%, 48%, and
49%) during the three experimental periods of our study, R
−
10, R, and R + 10, respectively.
The study was conducted in Tunisia, where Ramadan took place on 2 April and ended on
1 May 2022.
During this study, the periods of daily fasting were as follows: from 04:25–03:28 a.m. to
06:43–07:10 p.m. local time (approximately 14.5–15.5 h). When our two suhoor conditions
were evaluated during the last ten days of Ramadan, the daily fasting times were as follows:
from 03:54–03:38 a.m. to 07:01–07:10 p.m. local time (about 15–15.5 h).
Throughout the experimental period, participants were requested to maintain their
habitual physical activity and avoid strenuous activities or consuming any caffeine the
day before each session. Additionally, athletes were instructed to reproduce the first day’s
diet at each experimental trial and to standardize their meals for the 24 h before each
test. During the last ten days of Ramadan, all athletes adhered to the following lifestyles:
(a) Their sleep schedule consisted of several short intervals, specifically from approximately
11:30 p.m. to 1:30 a.m., 2:30 a.m. to 7:00 a.m., and 2:30 p.m. to 4:00 p.m. (b) They consumed
two meals: the first at iftar between 7:00 p.m. and 7:30 p.m., and the second between
10:30 p.m. and 11:30 p.m. on days 22 and 24 to ensure an early Suhour; between 1:30 a.m.
and 2:30 a.m. on days 26 and 28 to ensure a late Suhour; or at one of these two time slots
in the remaining days. (c) The athletes engaged in only one daily training session, which
took place from 9:00 p.m. to 10:00 p.m. During the testing trials, only tactical and technical
training sessions were allowed in order to prevent strenuous activities that could impact
our outcomes.
Eur. J. Investig. Health Psychol. Educ. 2023,13 2164
2.2.1. The Pittsburgh Sleep Quality Index (PSQI)
As described by Bougrine et al. [
35
], the validated Arabic version of the Pittsburgh
Sleep Quality Index [
32
] was used to assess the subjective quality of sleep throughout
the course of the previous month and for the duration of each experimental test period
(10 consecutive days).
2.2.2. Dietary Intake Analysis
As described by Bougrine et al. [
35
], participants recorded their food intake in a food
consumption diary throughout the span of a 10-day period during each of the three testing
periods (R −10, R, and R + 10).
2.2.3. Countermovement Jump Test
The participants executed a quick vertical jump with downward eccentric and upward
concentric moves while standing upright. They were instructed to jump as high as they
could and land in the same spot while keeping both hands on their hips to minimize the
impact of the arm swing. The Microgate software (Optojump software, version 1.10.50)
and the Optojump-next device (Bolzano, Italy) were both used. For analysis, only the jump
height (cm) was recorded. Throughout the test, each participant completed three trials,
separated by a two-minute recovery period, and the highest jump achieved among these
three trials was recorded for subsequent analysis.
2.2.4. Modified Agility t-Test (MATT)
The modified agility t-test involved multidirectional sprinting, shuffling, and
backpedaling [
36
,
37
]. A timing gate (Witty, Microgate
®
, Bolzano, Italy) was used to record
time at the start/finish line (the same line for this test), while athletes began the test 0.5 m
behind the gate. Participants began with a 5 m linear sprint to cone B, followed by a 2.5 m
leftward shuffle to cone C, a 5 m rightward shuffle to cone D, a 2.5 m leftward shuffle back
to cone B, and a 5 m linear backpedal to cone A. For each trial, the total distance covered
was 20 m. The MAT performance score was the fastest time from two trials, interspersed
with three minutes of rest.
2.2.5. Repeated Sprint Ability (RSA)
Similar to previous studies on female athletes [
9
,
38
,
39
], repeated sprint ability (RSA)
testing involved six maximal 2
×
12.5 m shuttle sprints, with 20 s of passive recovery
between sprints and 180
◦
turns. The RSA was established to measure repeated sprints
with a change in direction. The timing gates (Witty, Microgate
®
, Bolzano, Italy) were used
to record the times. Athletes were verbally motivated during testing and instructed to
get into the starting position 0.5 m behind the starting line 6 seconds prior to the start of
each sprint until the next start signal. The digital timer started automatically when the
photocell beam was disrupted. A light panel (Microgate
®
, Bolzano, Italy) was then used to
visually give participants a countdown of 3 s. They sprinted for 12.5 m from the starting
line, touched the second line with one foot, and then returned to the starting line with as
much speed as possible. Participants were given instructions to complete all sprints as
quickly as possible. For analysis, the best sprint (RSAbest) and the mean time of all sprints
(RSAmean) were retained.
2.2.6. Rating of Perceived Exertion (RPE)
The RPE scale is a valid predictor of physical discomfort, has high psychometric
qualities, and has a significant correlation with various other physiological exertion mea-
surements. The score on the [
40
] 10-point scale runs from 0 (nothing; represents how
you feel when sitting in a chair) to 10 (very, very heavy; represents how you feel after
performing a very, very hard exercise).
Eur. J. Investig. Health Psychol. Educ. 2023,13 2165
2.3. Procedure
The experimental design is displayed in Figure 1. In order to reduce learning effects
during the experiment and guarantee high-quality results, all players were familiarized
with the experimental protocol and the equipment throughout the course of the two weeks
before the study at 08:00 a.m. and 05:00 p.m.
Eur. J. Investig. Health Psychol. Educ. 2023, 13, x FOR PEER REVIEW 6
2.3. Procedure
The experimental design is displayed in Figure 1. In order to reduce learning effects
during the experiment and guarantee high-quality results, all players were familiarized
with the experimental protocol and the equipment throughout the course of the two
weeks before the study at 08:00 a.m. and 05:00 p.m..
Figure 1. Study design. R − 10: the 10 days before Ramadan, R: Ramadan, R1: First 10 days of Ram-
adan, R2: Second 10 days of Ramadan, R3: Last 10 days of Ramadan, R + 10: the 10 days before
Ramadan, R(ES): Early Suhoor, R(LS): Late Suhoor, PSQI: Pisburgh Sleep Quality Index, OT: Oral
temperature, CMJ: countermovement jump test, MATT: Modified agility t test, RSA: Repeated sprint
ability test, RPE: Rating of perceived exertion; all times given are expressed in local time (GMT + 1
h).
This study followed a randomized counterbalanced crossover trial where all partici-
pants were tested under four different conditions: the ten days prior to Ramadan (R − 10),
the final ten days of Ramadan (R), including two conditions: Early Suhoor R(LS) at day 22
and 24 of Ramadan and Late Suhoor R(LS) at days 26 and 28 of Ramadan, and the ten
days immediately following Ramadan (R + 10). Athletes completed two counterbalanced
test trials throughout each condition, with only one test session per day, one in the morn-
ing (08:00–09:00 a.m.) and one in the afternoon (05:00–06:00 p.m.), separated by a mini-
mum of 48 h. These two times of day were chosen because they roughly refer to the
batyphase and acrophase of maximum short-term performance and oral temperature [41]
(Figure 1).
Suhoor Protocol
During the Ramadan period, players randomly achieved two conditions concerning
the timing of suhoor: R(ES): Early Suhoor (consumed at 10:30 p.m.) and R(LS): Late Suhoor
(consumed at 03:30 a.m.). All athletes received the same standard suhoor, with the caloric
intake set at 650–700 kcal (60% carbohydrates, 20% protein, and 20% fat) with two glasses
of water (225 mL per glass), based on the results of the food diary checked and evaluated
by the same dietician before and throughout Ramadan. In terms of macronutrient intake,
the suhoor quality and quantity did not differ much from the athletes baseline routine;
Figure 1.
Study design. R
−
10: the 10 days before Ramadan, R: Ramadan, R1: First 10 days of
Ramadan, R2: Second 10 days of Ramadan, R3: Last 10 days of Ramadan, R + 10: the 10 days
before Ramadan, R(ES): Early Suhoor, R(LS): Late Suhoor, PSQI: Pittsburgh Sleep Quality Index, OT:
Oral temperature, CMJ: countermovement jump test, MATT: Modified agility ttest, RSA: Repeated
sprint ability test, RPE: Rating of perceived exertion; all times given are expressed in local time
(GMT + 1 h).
This study followed a randomized counterbalanced crossover trial where all partici-
pants were tested under four different conditions: the ten days prior to Ramadan (R
−
10),
the final ten days of Ramadan (R), including two conditions: Early Suhoor R(LS) at day 22
and 24 of Ramadan and Late Suhoor R(LS) at days 26 and 28 of Ramadan, and the ten days
immediately following Ramadan (R + 10). Athletes completed two counterbalanced test
trials throughout each condition, with only one test session per day, one in the morning
(08:00–09:00 a.m.) and one in the afternoon (05:00–06:00 p.m.), separated by a minimum of
48 h. These two times of day were chosen because they roughly refer to the batyphase and
acrophase of maximum short-term performance and oral temperature [41] (Figure 1).
Suhoor Protocol
During the Ramadan period, players randomly achieved two conditions concerning
the timing of suhoor: R(ES): Early Suhoor (consumed at 10:30 p.m.) and R(LS): Late Suhoor
(consumed at 03:30 a.m.). All athletes received the same standard suhoor, with the caloric
intake set at 650–700 kcal (60% carbohydrates, 20% protein, and 20% fat) with two glasses
of water (225 mL per glass), based on the results of the food diary checked and evaluated
by the same dietician before and throughout Ramadan. In terms of macronutrient intake,
the suhoor quality and quantity did not differ much from the athlete’s baseline routine;
Eur. J. Investig. Health Psychol. Educ. 2023,13 2166
however, the two conditions differed in the time at which they had their meals. It’s worth
noting that athletes were under continuous surveillance during both different experimental
conditions and that the ingestion was verified by an experimenter. Subjects ate their last
meal at least 20 min before going to bed. No instructions for sleeping time were given to
participants after the suhoor; however, our instructions were limited to the timing of the
suhoor. No food and/or beverage was allowed for participants after taking the standard
suhoor meal.
2.4. Statistical Analysis
The required sample size was determined a priori using the G*Power 3.1 software [
42
].
The values for
α
and power were set to 0.05 and 0.95, respectively. Effect sizes have been
estimated to be 0.39 based on studies with identical methodologies [
14
,
43
] and discus-
sions among the authors. To reach the desired power, data from at least 16 participants
was considered sufficient to minimize the risk of incurring the probability of a type 2
statistical error.
All statistical tests were processed with STATISTICA 10 software (StatSoft, Paris,
France). Means
±
SD (standard deviation) values were calculated for each variable. All
data were normally distributed, as confirmed using the Shapiro–Wilk test. For the effect of
time of suhoor, a two-way repeated measures ANOVA [4 (Testing conditions)
×
2 (Time of
the day)] was conducted. Where appropriate, significant differences between means were
tested using Tukey’s HSD Post hoc test. A one-way repeated measures ANOVA (3 testing
periods) was used to analyze the following data: PSQI, body mass, BMI, energy intake, fat
(g), carbohydrate (g), and protein (g). When significant differences were reported, Tukey’s
HSD Post hoc test was used to test between means. The magnitude of the difference
between age groups was evaluated using the effect size statistic (
ηp2
). The criteria used to
determine the effect sizes were as follows: 0.01 denoted a small effect size, 0.06 represented
a moderate effect size, and 0.14 indicated a large effect size [
44
]. Standardized effect size
(Cohen’s d) analysis was used to interpret the magnitude of differences between variables
and classified according to [
45
] as trivial (d
≤
0.20); small (0.20 < d
≤
0.60); moderate
(
0.60 < d ≤1.20
); large (1.20 < d
≤
2.0); very large (2.0 < d
≤
4.0); and extremely large
(d > 4.0). A significant level was considered as p≤0.05.
3. Results
3.1. The Pittsburgh Sleep Quality Index (PSQI)
The one-way ANOVA test demonstrated significant main effects of conditions on
sleep latency (F (2, 36) = 4.12, p < 0.05,
ηp2
= 0.18), sleep duration (F (2, 36) = 53.69,
p < 0.001, ηp2= 0.74
), sleep quality (F (2, 36) = 88.98, p < 0.001,
ηp2
= 0.83), sleep disturbances
(
F (2, 36) = 36.29,
p < 0.001,
ηp2
= 0.66), daytime dysfunction (F (2, 36) = 27.76, p < 0.001,
ηp2
= 0.60), and total scores of PSQI (F (2, 36) = 66.73, p < 0.001,
ηp2
= 0.78), while sleep
efficiency and the use of sleeping medication remained unaffected. The Tukey test revealed
the following significant findings: (i) Sleep latency was longer during R compared to
R−10
(p < 0.05), (ii) Sleep duration decreased significantly during R and R + 10 (both p < 0.001)
compared to R
−
10, (iii) The total scores of PSQI, sleep quality, and sleep disturbance
scores increased significantly during R and R + 10 (all p < 0.001) compared to R
−
10, and
(iiii) The daytime dysfunction score was higher during R (p < 0.001) and R + 10 (p < 0.05)
compared to R −10 (Table 1).
3.2. Dietary Intake Analysis, Body mass, and BMI
The analysis revealed no significant statistical differences in the daily mean energy and
macronutrient intake, body mass, or BMI among the participants across the three testing
phases (all p> 0.05; Table 2).
Eur. J. Investig. Health Psychol. Educ. 2023,13 2167
Table 1.
Measurement of the subjective quality of sleep recorded during 10 days before Ramadan
(R −10), Ramadan (R), and 10 days following Ramadan (R + 10).
R−10 R R + 10
Sleep latency (min) 16 ±2.4 * 17 ±3.4 &16.6 ±2.2
Sleep effciency (%) 95.2 ±4.2 94.8 ±4.2 94.4 ±4.8
Sleep duration (h) 7.5 ±0.8 *#6±0.7 &# 6.6 ±0.8 &*
Sleep quality (AU) 0.5 ±0.3 *#2.2 ±0.6 &# 1.4 ±0.6 &*
Sleep disturbances (AU) 0.42 ±0.29 *#1.35 ±0.44 &# 0.9 ±0.4 &*
Daytime dysfunction (AU) 0.25 ±0.22 *#1.15 ±0.5 &# 0.59 ±0.37 &*
Total score of PSQI (AU) 2±0.9 *#7.2 ±1.8 &# 4.4 ±1.9 &*
AU: arbitrary units; PSQI: The Pittsburgh Sleep Quality Index;
&
: Significant difference compared to R
−
10;
*: Significant difference compared to R; #: Significant difference compared to R + 10.
Table 2.
Differences in mean values
±
standard deviation (SD) of body mass, body mass index (BMI),
and estimated daily calories and macronutrient intake were recorded across three testing periods:
10 days before Ramadan (R
−
10), 10 last days of Ramadan (R), and 10 days following Ramadan
(R + 10).
R−10 R R + 10 p-Value
Body mass (kg) 61.5 ±6.9 61.2 ±7 61.5 ±7.2 0.12
Body mass index (kg/m
2
)
21.6 ±1.8 21.5 ±1.8 21.6 ±1.9 0.12
Protein (g/d) 66.4 ±12.1 64.3 ±15.1 69.5 ±12.4 0.31
Carbohydrate (g/d) 404.2 ±68.3 411.4 ±62.6 408.6 ±63 0.13
Fat (g/d) 90.5 ±10.4 90.8 ±10.4 88.9 ±10.8 0.47
Energy intake (kcal/day) 2697.3 ±269.6 2720.4 ±270.9 2712.9 ±286.3 0.63
3.3. Oral Temperature (OT)
Statistical analysis of OT revealed significant main effects of Conditions (F (3, 54) = 6,
p < 0.01,
ηp2
= 0.24) and Time-of-day (F (1, 18) = 468, p < 0.001,
ηp2
= 0.96). However, there
was no significant Conditions
×
Time-of-day interaction (F (3, 54) = 0, p= 0.92,
ηp2
= 0.008).
Post hoc analysis indicated that OT values were higher in the afternoon compared to the
morning in all three testing conditions (all p<0.001) (Figure 2).
Eur. J. Investig. Health Psychol. Educ. 2023, 13, x FOR PEER REVIEW 8
Sleep quality (AU) 0.5 ± 0.3 *# 2.2 ± 0.6 &# 1.4 ± 0.6 &*
Sleep disturbances (AU) 0.42 ± 0.29 *# 1.35 ± 0.44 &# 0.9 ± 0.4 &*
Daytime dysfunction (AU) 0.25 ± 0.22 *# 1.15 ± 0.5 &# 0.59 ± 0.37 &*
Total score of PSQI (AU) 2 ± 0.9 *# 7.2 ± 1.8 &# 4.4 ± 1.9 &*
AU: arbitrary units; PSQI: The Pisburgh Sleep Quality Index; &: Significant difference compared to
R − 10; *: Significant difference compared to R; #: Significant difference compared to R + 10.
3.2. Dietary Intake Analysis, Body mass, and BMI
The analysis revealed no significant statistical differences in the daily mean energy
and macronutrient intake, body mass, or BMI among the participants across the three test-
ing phases (all p > 0.05; Table 2).
Table 2. Differences in mean values ± standard deviation (SD) of body mass, body mass index (BMI),
and estimated daily calories and macronutrient intake were recorded across three testing periods:
10 days before Ramadan (R − 10), 10 last days of Ramadan (R), and 10 days following Ramadan (R
+ 10).
R − 10 R R + 10 p-Value
Body mass (kg) 61.5 ± 6.9 61.2 ± 7 61.5 ± 7.2 0.12
Body mass index (kg/m2) 21.6 ± 1.8 21.5 ± 1.8 21.6 ± 1.9 0.12
Protein (g/d) 66.4 ± 12.1 64.3 ± 15.1 69.5 ± 12.4 0.31
Carbohydrate (g/d) 404.2 ± 68.3 411.4 ± 62.6 408.6 ± 63 0.13
Fat (g/d) 90.5 ± 10.4 90.8 ± 10.4 88.9 ± 10.8 0.47
Energy intake (kcal/day) 2697.3 ± 269.6 2720.4 ± 270.9 2712.9 ± 286.3 0.63
3.3. Oral Temperature (OT)
Statistical analysis of OT revealed significant main effects of Conditions (F (3, 54) = 6,
p < 0.01, ηp2 = 0.24) and Time-of-day (F (1, 18) = 468, p < 0.001, ηp2 = 0.96). However, there
was no significant Conditions × Time-of-day interaction (F (3, 54) = 0, p = 0.92, ηp2 = 0.008).
Post hoc analysis indicated that OT values were higher in the afternoon compared to the
morning in all three testing conditions (all p <0.001) (Figure 2).
Figure 2. Mean ± SD values of Oral Temperature (OT) measured at 08:00 a.m. and 05:00 p.m. during
10 days before Ramadan R − 10, Ramadan Early Suhoor R(ES), Ramadan Late Suhoor R(LS), and 10
days following Ramadan R + 10. * (p < 0.001): Significant difference compared to 05:00 p.m..
3.4. CMJ
The two-way ANOVA showed significant main effects of Time-of-day (F (1, 18) =
11.55, p < 0.01, ηp2 = 0.39) and Conditions (F (3, 54) = 26.29, p < 0.001, ηp2 = 0.59). Addition-
ally, a significant Conditions × Time-of-day interaction was found (F (3, 54) = 12.44, p <
Figure 2.
Mean
±
SD values of Oral Temperature (OT) measured at 08:00 a.m. and 05:00 p.m. during
10 days before Ramadan R
−
10, Ramadan Early Suhoor R(ES), Ramadan Late Suhoor R(LS), and
10 days following Ramadan R + 10. * (p< 0.001): Significant difference compared to 05:00 p.m.
Eur. J. Investig. Health Psychol. Educ. 2023,13 2168
3.4. CMJ
The two-way ANOVA showed significant main effects of Time-of-day (F (1, 18) = 11.55,
p < 0.01,
ηp2
= 0.39) and Conditions (F (3, 54) = 26.29, p < 0.001,
ηp2
= 0.59). Additionally,
a significant Conditions
×
Time-of-day interaction was found (F (3, 54) = 12.44, p < 0.001,
ηp2
= 0.40). The post hoc test demonstrated that during R
−
10, R(LS), and R + 10, CMJ
performances were higher in the afternoon than in the morning (all p< 0.001) (Figure 3).
These findings revealed that CMJ performance was reduced in the afternoon compared to
R
−
10 throughout the R (ES) (p< 0.001) (
−
3, 2%). Additionally, CMJ was greater during
R(LS) than R(ES) only in the afternoon (p< 0.001) (Figure 3).
Eur. J. Investig. Health Psychol. Educ. 2023, 13, x FOR PEER REVIEW 9
0.001, ηp2 = 0.40). The post hoc test demonstrated that during R − 10, R(LS), and R + 10,
CMJ performances were higher in the afternoon than in the morning (all p < 0.001) (Figure
3). These findings revealed that CMJ performance was reduced in the afternoon compared
to R − 10 throughout the R (ES) (p < 0.001) (−3, 2%). Additionally, CMJ was greater during
R(LS) than R(ES) only in the afternoon (p < 0.001) (Figure 3).
Figure 3. Mean ± SD values of Countermovement Jump Test (CMJ) and Modified Agility t-Test
(MATT) performances recorded at 08:00 a.m. and 05:00 p.m. during 10 days before Ramadan R − 10,
Ramadan Early Suhoor R(ES), Ramadan Late Suhoor R(LS), and 10 days following Ramadan R + 10.
* Significant difference compared to 08:00 a.m. (p < 0.001). a (p < 0.05), aa (p < 0.01), and aaa (p < 0.001):
Significant difference compared to R − 10 at the same time of day. b (p < 0.01) and bb (p < 0.001):
Significant difference compared to R(ES) at the same time of day. c (p< 0.01), cc (p < 0.001) Significant
difference compared to R(LS) at the same time of day. d (p < 0.01), dd (p < 0.001) significant difference
compared to R + 10 at the same time of day.
3.5. MATT
There were a significant main effects of Time-of-day (F (1, 18) = 14.95, p < 0.01, ηp2 =
0.45) and Conditions (F (3, 54) = 143.14, p < 0.001, ηp2= 0.88), also a significant Conditions
× Time-of-day interaction (F (3, 54) = 58.94, p < 0.001, ηp2= 0.760), where MATT performance
was beer in the afternoon than in the morning during R − 10 and R + 10 (both p < 0.001)
(Figure 3). In comparison with R − 10, MATT decreased during R(ES) (10, 7%) and R(LS)
(5, 8%) and R + 10) (1, 9%) in the afternoon (p < 0.001, p < 0.001, p < 0.05, respectively) and
only during R(ES) in the morning (p < 0.01) (1, 9%). Moreover, MATT performance was
Figure 3.
Mean
±
SD values of Countermovement Jump Test (CMJ) and Modified Agility t-Test
(MATT) performances recorded at 08:00 a.m. and 05:00 p.m. during 10 days before Ramadan
R−10
,
Ramadan Early Suhoor R(ES), Ramadan Late Suhoor R(LS), and 10 days following Ramadan R + 10.
* Significant difference compared to 08:00 a.m. (p< 0.001).
a
(p< 0.05),
aa
(p< 0.01), and
aaa
(p< 0.001):
Significant difference compared to R
−
10 at the same time of day.
b
(p< 0.01) and
bb
(p< 0.001):
Significant difference compared to R(ES) at the same time of day.
c
(p< 0.01),
cc
(p< 0.001) Significant
difference compared to R(LS) at the same time of day.
d
(p< 0.01),
dd
(p< 0.001) significant difference
compared to R + 10 at the same time of day.
3.5. MATT
There were a significant main effects of Time-of-day (F (1, 18) = 14.95, p < 0.01,
ηp2= 0.45
) and Conditions (F (3, 54) = 143.14, p < 0.001,
ηp2
= 0.88), also a significant
Conditions
×
Time-of-day interaction (F (3, 54) = 58.94, p < 0.001,
ηp2
= 0.760), where MATT
performance was better in the afternoon than in the morning during R
−
10 and R + 10
Eur. J. Investig. Health Psychol. Educ. 2023,13 2169
(both p< 0.001) (Figure 3). In comparison with R
−
10, MATT decreased during R(ES)
(10, 7%) and R(LS) (5, 8%) and R + 10) (1, 9%) in the afternoon (p< 0.001, p< 0.001, p< 0.05,
respectively) and only during R(ES) in the morning (p< 0.01) (1, 9%). Moreover, MATT
performance was lower during R(ES) compared to R(LS) in the afternoon (p< 0.001) and in
the morning (p > 0.01) (Figure 3).
3.6. RSA
3.6.1. RSAmean
There was a significant effect of Conditions (F (3, 54) = 72.14, p < 0.001,
ηp2
= 0.80),
Time-of-day (F (1, 18) = 9.06, p < 0.01,
ηp2
= 0.33), and Conditions
×
Time-of-day interaction
(F (3, 54) = 22.39, p < 0.001,
ηp2
= 0.55). RSA
mean
performance was better in the afternoon
than in the morning during R
−
10, R(LS), and R + 10 (p< 0.001, p< 0.01, p< 0.001,
respectively) (Figure 4). In comparison with R
−
10, RSA
mean
performance decreased
during R(ES) (5, 8%) and R(LS) (2, 9%) in the afternoon (both p< 0.001), but only during
R(ES) in the morning (p< 0.001) (1, 8%). Furthermore, RSA
mean
was notably lower during
R(ES) when compared to R(LS) in both the afternoon (p< 0.001) and the morning (p< 0.01)
(Figure 4).
Eur. J. Investig. Health Psychol. Educ. 2023, 13, x FOR PEER REVIEW 10
lower during R(ES) compared to R(LS) in the afternoon (p < 0.001) and in the morning (p
> 0.01) (Figure 3).
3.6. RSA
3.6.1. RSAmean
There was a significant effect of Conditions (F (3, 54) = 72.14, p < 0.001, ηp2 = 0.80),
Time-of-day (F (1, 18) = 9.06, p < 0.01, ηp2 = 0.33), and Conditions × Time-of-day interaction
(F (3, 54) = 22.39, p < 0.001, ηp2 = 0.55). RSAmean performance was beer in the afternoon
than in the morning during R − 10, R(LS), and R + 10 (p < 0.001, p < 0.01, p < 0.001, respec-
tively) (Figure 4). In comparison with R − 10, RSAmean performance decreased during R(ES)
(5, 8%) and R(LS) (2, 9%) in the afternoon (both p< 0.001), but only during R(ES) in the
morning (p < 0.001) (1,8%). Furthermore, RSAmean was notably lower during R(ES) when
compared to R(LS) in both the afternoon (p < 0.001) and the morning (p < 0.01) (Figure 4).
Figure 4. Mean ± SD values of Repeated Sprint Ability (RSA) measured at 08:00 a.m. and 05:00 p.m.
during 10 days before Ramadan R − 10, Ramadan Early Suhoor R(ES), Ramadan Late Suhoor R(LS),
and 10 days following Ramadan R + 10. *, ** Significant difference compared to 08:00 a.m. (p < 0.01,
and p < 0.001, respectively). a (p < 0.05) and aa (p < 0.001) Significant difference compared to R − 10 at
the same time of day. b (p < 0.05), bb (p < 0.01), and bbb (p < 0.001) Significant difference compared to
R(ES) at the same time of day. c (p < 0.01) and cc (p < 0.001) Significant difference compared to R(LS)
at the same time of day. d Significant difference compared to R + 10 at the same time of day (p <
0.001).
3.6.2. RSAbest
There was a significant effect of Conditions (F (3, 54) = 84.90, p < 0.001, ηp2 = 0.82),
Time-of-day (F (1, 18) = 9.19, p < 0.01, ηp2 = 0.33), and Conditions × Time-of-day interaction
Figure 4.
Mean
±
SD values of Repeated Sprint Ability (RSA) measured at 08:00 a.m. and 05:00 p.m.
during 10 days before Ramadan R
−
10, Ramadan Early Suhoor R(ES), Ramadan Late Suhoor R(LS),
and 10 days following Ramadan R + 10. *, ** Significant difference compared to 08:00 a.m. (p< 0.01,
and p< 0.001, respectively).
a
(p< 0.05) and
aa
(p< 0.001) Significant difference compared to R
−
10 at
the same time of day.
b
(p< 0.05),
bb
(p< 0.01), and
bbb
(p< 0.001) Significant difference compared
to R(ES) at the same time of day.
c
(p< 0.01) and
cc
(p< 0.001) Significant difference compared to
R(LS) at the same time of day.
d
Significant difference compared to R + 10 at the same time of day
(p< 0.001).
Eur. J. Investig. Health Psychol. Educ. 2023,13 2170
3.6.2. RSAbest
There was a significant effect of Conditions (F (3, 54) = 84.90, p < 0.001,
ηp2
= 0.82),
Time-of-day (F (1, 18) = 9.19, p < 0.01,
ηp2
= 0.33), and Conditions
×
Time-of-day interaction
(F (3, 54) = 29.02, p < 0.001,
ηp2
= 0.61). The post hoc test revealed that RSA
best
performance
was higher in the afternoon than in the morning during R
−
10, R(LS), and R + 10 (p< 0.001,
p< 0.01, p< 0.001, respectively) (Figure 4). Compared to R
−
10, RSA
best
performance
decreased during R(ES) (6, 4%) and R(LS) (3, 6%) in the afternoon (both p< 0.001) and only
during R(ES) in the morning (p< 0.05) (1, 4%). Likewise, compared to R(ES), RSA
best
was
better during R(LS) only in the afternoon (p< 0.001) (Figure 4).
3.7. RPE
The RPE scores showed significant main effects for both Conditions (F (3, 54) = 106.90,
p < 0.001,
ηp2
= 0.85) and Time-of-day (F (1, 18) = 37.96, p < 0.001,
ηp2
= 0.67). Additionally,
there was a significant interaction between Conditions
×
Time-of-day (F (3, 54) = 42.46,
p < 0.001
,
ηp2
= 0.70). The post hoc analysis revealed that RPE scores were significantly
higher in the afternoon than in the morning during R(ES), R(LS), and R + 10 (p< 0.001,
p< 0.001
,p< 0.05, respectively). However, no significant difference was observed during
R−10
(p> 0.05) (Figure 5). RPE scores increased significantly during R(ES) (24, 9%) and
R(LS) (17, 7%) in the afternoon (both p< 0.001) but only during R(ES) in the morning
(p < 0.001
) (7, 8%) compared to (R
−
10). When compared to R(LS), RPE scores were higher
during R(ES) in both the afternoon (p< 0.001) and in the morning (p< 0.001) (Figure 5).
Eur. J. Investig. Health Psychol. Educ. 2023, 13, x FOR PEER REVIEW 11
(F (3, 54) = 29.02, p < 0.001, ηp2 = 0.61). The post hoc test revealed that RSAbest performance
was higher in the afternoon than in the morning during R − 10, R(LS), and R + 10 (p < 0.001,
p < 0.01, p < 0.001, respectively) (Figure 4). Compared to R − 10, RSAbest performance de-
creased during R(ES) (6, 4%) and R(LS) (3, 6%) in the afternoon (both p < 0.001) and only
during R(ES) in the morning (p < 0.05) (1, 4%). Likewise, compared to R(ES), RSAbest was
beer during R(LS) only in the afternoon (p < 0.001) (Figure 4).
3.7. RPE
The RPE scores showed significant main effects for both Conditions (F (3, 54) = 106.90,
p < 0.001, ηp2 = 0.85) and Time-of-day (F (1, 18) = 37.96, p < 0.001, ηp2 = 0.67). Additionally,
there was a significant interaction between Conditions × Time-of-day (F (3, 54) = 42.46, p <
0.001, ηp2 = 0.70). The post hoc analysis revealed that RPE scores were significantly higher
in the afternoon than in the morning during R(ES), R(LS), and R + 10 (p < 0.001, p < 0.001,
p < 0.05, respectively). However, no significant difference was observed during R − 10 (p >
0.05) (Figure 5). RPE scores increased significantly during R(ES) (24, 9%) and R(LS) (17,
7%) in the afternoon (both p < 0.001) but only during R(ES) in the morning (p < 0.001) (7,
8%) compared to (R − 10). When compared to R(LS), RPE scores were higher during R(ES)
in both the afternoon (p < 0.001) and in the morning (p < 0.001) (Figure 5).
Figure 5. Mean ± SD Scores of Rating of perceived exertion (RPE) recorded at 08:00 a.m. and 05:00
p.m. during 10 days before Ramadan R − 10, Ramadan Early Suhoor R(ES), Ramadan Late Suhoor
R(LS), and 10 days following Ramadan R + 10. *, ** Significant difference compared to 08:00 a.m. (p
< 0.05 and p < 0.001, respectively). a Significant difference compared to R − 10 at the same time of day
(p < 0.001). b Significant difference compared to R(ES) at the same time of day (p < 0.001). c Significant
difference compared to R(LS) at the same time of day (p < 0.001). d significant difference compared
to R + 10 at the same time of day (p < 0.001).
4. Discussion
The aim of the present study was to investigate the effect of suhoor timing during
RIF on short-term high-intensity physical performance in adolescent female handball
players. The main hypotheses formulated were that (i) RIF would negatively impact short-
term high-intensity physical performance primarily in the afternoon rather than the morn-
ing, and (ii) acute late Suhoor intake may mitigate the decline in short-term high-intensity
exercise performance caused by RIF when compared to an early Suhoor intake. The results
of our study supported these hypotheses and indicated that (i) RIF significantly impairs
short-term high-intensity physical performances and sleep parameters ; (ii) The timing of
suhoor consumed by athletes observing the fast during Ramadan affects short-term high-
intensity exercise; (iii) The acute late suhoor could minimize the physical performance
drop during the afternoon period of RIF and maintain the same morning performance,
beer than early suhoor consumption.
Figure 5.
Mean
±
SD Scores of Rating of perceived exertion (RPE) recorded at 08:00 a.m. and
05:00 p.m. during 10 days before Ramadan R
−
10, Ramadan Early Suhoor R(ES), Ramadan Late
Suhoor R(LS), and 10 days following Ramadan R + 10. *, ** Significant difference compared to
08:00 a.m. (
p< 0.05
and p< 0.001, respectively).
a
Significant difference compared to R
−
10 at the
same time of day (p< 0.001).
b
Significant difference compared to R(ES) at the same time of day
(
p< 0.001
).
c
Significant difference compared to R(LS) at the same time of day (p< 0.001).
d
significant
difference compared to R + 10 at the same time of day (p< 0.001).
4. Discussion
The aim of the present study was to investigate the effect of suhoor timing during RIF
on short-term high-intensity physical performance in adolescent female handball players.
The main hypotheses formulated were that (i) RIF would negatively impact short-term
high-intensity physical performance primarily in the afternoon rather than the morning,
and (ii) acute late Suhoor intake may mitigate the decline in short-term high-intensity
exercise performance caused by RIF when compared to an early Suhoor intake. The results
of our study supported these hypotheses and indicated that (i) RIF significantly impairs
short-term high-intensity physical performances and sleep parameters; (ii) The timing
of suhoor consumed by athletes observing the fast during Ramadan affects short-term
Eur. J. Investig. Health Psychol. Educ. 2023,13 2171
high-intensity exercise; (iii) The acute late suhoor could minimize the physical performance
drop during the afternoon period of RIF and maintain the same morning performance,
better than early suhoor consumption.
4.1. Effect of RIF
Our PSQI scores demonstrated that RIF substantially impairs sleep duration, with
a shift of 90 min compared to before RIF. This shift was accompanied by an increase in
the overall PSQI score (higher more than three times) and sleep quality (higher more than
four times) compared to before RIF. Whereas recent studies [
5
,
35
,
43
] have highlighted a
negative impact on subjective sleep quality during RIF, other studies revealed no significant
change in sleep quality or duration [
46
,
47
]. The inconsistencies in the effects of RIF on
sleep may be due to variations in methodology, study populations, or lifestyle differences.
Therefore, recently, it has been shown that the exclusive nighttime ingestion of enormous
quantities of food throughout this month, coupled with several lifestyle changes, can
diminish sleep quality and duration [
7
]. The total sleep quantity and quality and the
timing of the sleep constitute essential factors to facilitate recovery and achieve optimal
athletic performance [
48
]. This could explain the drop in performance observed during
this period of RIF. In the same vein, [
5
,
35
] suggested that the cumulative fatigue caused by
the repetitive partial sleep deprivation during RIF was the origin of the drop in physical
performance and a change in diurnal variation of these performances, not the diary intake.
RIF may disrupt sleep patterns, and inadequate or disrupted sleep can negatively affect
cognitive function and physical performance [
5
]. Indeed, it has been shown that insufficient
sleep can lead to reduced attention and slower reaction times, particularly in the late
afternoon [
49
,
50
]. It’s essential to acknowledge that getting less than the recommended
eight hours of sleep can result in cognitive performance deficits [
51
]. Hence, the significance
of mental well-being and cognitive abilities in achieving success in sports is increasingly
acknowledged, and this awareness extends to team ball players [52].
On the other hand, our findings indicated that RIF could indeed have a negative
impact on physical performance in athletes, particularly during the afternoon hours in both
conditions (RE) and (RL) of suhoor rather than the morning compared to before Ramadan
and immediately following RIF. These findings are in line with recent studies that examined
the diurnal variation of short-term maximal exercise during RIF, with a performance drop
observed only during the afternoon sessions for jump performance [
5
,
9
], agility [
9
,
35
], and
repeated sprint bouts [
5
,
35
]. Other studies, however, found no effect of RIF on squat jump
performance [
53
,
54
], agility [
14
], or repeated shuttle tests [
10
,
15
]. Methodological variables
such as fasting variables (including duration of fast, suhoor time, period of RIF, and the
season of fast), age, gender, chronotypes, and physical level of participants could explain
discrepancies between studies.
Regardless of the suhoor timing, this drop in performance observed mainly in the
afternoon is primarily due to the fasting duration (about 15.5 h during our study). In fact,
due to the prolonged duration of fasting during Ramadan (13.5 h during afternoon sessions
for R (LS) and 18.5h during afternoon sessions for R (ES)), athletes may experience de-
creased glycogen stores, lower blood glucose levels after more than 6h of the last meal [
55
],
and overall reduced energy availability, leading to fatigue and decreased performance [
56
].
Furthermore, the lack of fluid intake during the day can lead to dehydration, which can
impair an athlete’s ability to maintain optimal performance levels during physical ac-
tivities, especially during the hot months [
57
]. Dehydration can impair cardiovascular
function, thermoregulation, and muscular performance, negatively impacting physical
performance [
8
]. However, it should be noted that RIF has also been linked to disturbances
in the body’s natural sleep-wake patterns, as well as alterations in the levels of various
hormones, including leptin, adiponectin, ghrelin, cortisol, and melatonin [
58
–
60
]. These
physiological changes have been observed during RIF due to abrupt shifts in meal times,
modifications in dietary choices, variations in food group intake, and disruptions in sleep
patterns, all of which have the potential to disrupt the metabolic effects of RIF [
61
,
62
]. All
Eur. J. Investig. Health Psychol. Educ. 2023,13 2172
these modifications were linked with an advance or a delay in circadian rhythm phases [
63
],
stress, anxiety, or concerns about fasting that may affect an athlete’s mindset and motiva-
tion, potentially impacting their performance [
47
,
64
], and deterioration of sleep quality
and duration [
7
]. Furthermore, our findings regarding body mass and BMI align with a
recent systematic review [
65
], which affirmed the lack of substantial evidence supporting a
decrease in body composition indicators among athletes during Ramadan. Hence, it has
been recently demonstrated that an increase in muscular hypertrophy and the accompa-
nying rise in body weight among athletes, along with a reduction in adipose tissue levels,
were considered favorable factors contributing to the enhancement of motor potential [
66
].
This led us to hypothesize that the lack of motor potential observed during afternoon
sessions may be attributed to sleep disturbances and/or the timing of the suhoor meal, not
the amount of caloric intake. Furthermore, compared to non-Ramadan time, inadequate
sleep and feelings of malaise increase fatigue and perceived effort in response to the same
exercise load [
67
,
68
]. Further, studies conducted during non-RIF periods indicated that
dietary timing, quantity, and quality influenced both sleep duration and quality [
69
,
70
]. As
a result, it is crucial to investigate the link between sleep quality and caloric intake timing.
4.2. Effect of Time of the Day
The present study indicated that the short-term high-intensity physical performance
of female athletes is time-dependent, which suggests that the timing of physical exercise
may have an impact on performance outcomes. This finding implies that athletes may
experience variations in their performance levels depending on the time of day when they
engage in physical activities, with better performances recorded in the afternoon before the
Ramadan period. Our results are in line with a recent meta-analysis [
71
] that demonstrated
that late afternoon and early evening (between 04:00 p.m. and 07:30 p.m.) tend to be
optimal times for short-term high-intensity physical performance due to numerous factors
such as increased core body temperature [
72
], improved muscle function [
73
,
74
], increased
hormone levels [
74
,
75
] and enhanced cognitive functions such as reaction times [
76
]. These
factors can lead to better jumping abilities [
5
,
77
], agility [
9
,
77
], and repeated shuttles [
5
,
9
,
77
]
during physical exercises in the afternoon for female handball players. However, it is worth
noting that other studies have not found a significant difference in performance based on
the time of day in several aspects of short-term maximal exercise [
78
,
79
]. Factors such
as individual variations in chronotype (whether one is a “morning player” or “evening
player”, but in our study, it is “neither” chronotype), personal preferences and/or time
from wake-up [
80
], training status and schedules [
41
], specific sport requirements, and
differences in testing protocols can influence the outcomes. Additionally, our results
indicated that the diurnal variations of short-term high-intensity physical performance
are Ramadan-dependent. The impact of the time of day on physical performance appears
to diminish during Ramadan due to a decline in performance observed in the afternoon.
These daily fluctuations disappeared, blunted, and/or reversed during this month, which
is in agreement with those of [5,35,43].
4.3. Effect of Suhoor Timing
Regarding the effect of suhoor timing, an important finding of our study is that there
was a significant effect of the timing of suhoor in short-term high-intensity exercise. We
found that a late suhoor intake may help to (i) enhance the decline observed in these
performances in the afternoon during RIF and (ii) maintain morning performance values
similar to those of before Ramadan at the same time of day. We speculate that one possible
explanation for the decrease in performance in both conditions of suhoor compared to
baseline values, particularly in the afternoon, is that refraining from eating and drinking for
extended periods prior to and during physical exercise can result in reduced accessibility
and utilization of energy sources, as well as alterations in hormonal and metabolic responses
that occur simultaneously with dehydration [
24
,
25
]. In fact, this prolonged fasting period
can result in various metabolic adaptations that can affect physical performance by reducing
Eur. J. Investig. Health Psychol. Educ. 2023,13 2173
total protein synthesis [
22
] and creating low energy availability [
23
]. Recently, it has been
shown that lipids and hormones were also affected by meal timing rather than glucose
levels during time-restricted feeding [
81
]. Given that glucose is the primary energy source
for humans and that glucose metabolism is time-dependent (meaning it depends on how
long it has been since the last meal), blood glucose levels drop rapidly after ingesting a
carbohydrate meal. Depending on the amount of glycogen stored in the liver and the
subsequent energy expenditure, glycogen levels will be lowered, and fat metabolism
will become the energy source via ketone body synthesis over the 12- to 36-hour period
following carbohydrate intake [
82
]. Consequently, a decline in blood glucose levels could
alter hormone levels, leading to symptoms such as fatigue (which could explain the higher
afternoon RPE scores, especially after early suhoor condition), dizziness, hunger, weakness,
and a decrease in overall athletic performance [
83
]. In the morning, athletes typically have
the opportunity to consume a pre-dawn meal (suhoor) to provide some fuel and hydration
for the day ahead. However, as the day progresses and the fasting period extends, these
stored energy reserves gradually deplete. This phenomenon can be possibly explained by
the difference in the timing of the “suhoor effect” between the afternoon fasting duration
(around 15.5 h vs. 20.5 h) and the morning fasting duration (around 4.5 h vs. 9.5 h) in
the LS condition and ES condition, respectively. Only morning performance with late
suhoor intake (LS condition) remained unchanged because the fasting period was under 8
h (around 4.5 h). However, the most pronounced declines in performances were recorded
in the afternoon under ES condition, where the fasting duration extended to around 20.5 h.
Although research on the timing of meals during RIF is lacking and to the best of our
knowledge, current data indicates that meal timing may have the potential to affect athletes’
sleep patterns [
26
]. In agreement with our findings, calorie restriction has been associated
with prolonged sleep onset and reduced slow-wave sleep in overweight women [
27
]. A
recent study revealed that consuming more sugar in the evening and having a longer gap
between dinner and bedtime was linked to shorter total sleep duration [
84
]. Furthermore,
it has been demonstrated that minor adjustments in sleep-wake cycles and meal schedules
could potentially affect the overall performance patterns in short-distance running [
85
].
Our results are in line with previous studies that suggested that late suhoor ingestion can
help optimize hydration levels before the start of the fast, which is crucial for maintaining
optimal cardiovascular function, thermoregulation, and muscular performance [
86
,
87
]. In
addition, Chtourou et al. [
88
] also supposed that morning performance was not negatively
affected by fasting when athletes consumed a meal before sunrise, and Mhenni et al. [
9
]
suggested that consuming suhoor meal as late as permissible could be the origin of the
improvement in physical performance observed during Ramadan in the morning. Unfor-
tunately, the authors did not find any prior studies that had investigated the timing of
suhoor (pre-dawn meal) among athletes for comparison with our study results, although it
has been recently revealed that reducing or limiting energy intake during a time-restricted
feeding for 8 to 12 h causes the body to shift from glucose to fat for fuel [
81
]. Moreover,
carbohydrate intake during exercise assists in carbohydrate oxidation, minimizes hypo-
glycemia, and has beneficial impacts on the central nervous system [
23
,
81
]. Given that
nutritional timing is important when compared to breakfast, isocaloric meals with the
same nutritional composition seem to provide additional calories when ingested in the
evening. This could suggest that, in addition to what athletes decide to consume, when
they consume also affects their physiological response to food and postprandial glucose lev-
els [
23
]. In conclusion, the drop in physical performance during the afternoon of Ramadan
can be influenced by factors such as fasting duration, dehydration, energy and nutrient
deficits, the timing of the last meal of suhoor, circadian rhythms, sleep disturbances, and
psychological factors.
4.4. Strength and Limitations
To our knowledge, our study is one of the pioneers’ attempts to examine the relation-
ship between last-meal suhoor timing and short-term high-intensity performance among
Eur. J. Investig. Health Psychol. Educ. 2023,13 2174
athletes, based on a study of the diurnal variation of these performances in female ath-
letes. Some limitations of the present study should be taken into account. We conducted
measurements at two specific time points during the day before breaking the fast (in the
late afternoon and in the morning). To further investigate the effects of the timing of the
pre-dawn meal of suhour, future studies should consider including additional time points
in midday and in the evening after breaking the fast. Moreover, it’s important to note that
additional time points for suhour meal consumption will be necessary for future studies
to explore this research question specifically. It’s important to note that our study only
involved young female athletes. Therefore, the findings observed cannot be generalized
to adult males. Furthermore, the use of an auto-evaluated methodology to determine
energy and macronutrient composition and sleep parameters. This approach has known
weaknesses and may have played a role in the observed outcomes. It is worth noting that
individual variations exist, and some athletes may adapt better to fasting during Ramadan
than others, and the effectiveness of late suhoor ingestion may vary depending on factors
such as an athlete’s specific sport, training schedule, and personal preferences. Personal
preferences for the timing of suhoor and sleeping should be taken into account in future
investigations to explore this research question specifically. Lastly, it should be noted
that the absence of physiological variables, such as lactate levels, blood glucose levels,
and hormones (e.g., cortisol, adrenalin, and noradrenaline), is another limitation of our
current investigation. Therefore, future studies should aim to replicate our study while
also monitoring and controlling these parameters.
5. Conclusions
The timing of suhoor, the pre-dawn meal consumed by athletes observing the fast
during Ramadan, affects short-term high-intensity exercise. The findings suggest that a
late suhoor, consumed closer to pre-dawn time, attenuates the decline in the performance
of short-term high-intensity exercise caused by RIF, compared to early suhoor intake. The
results provided further evidence for the advantageous effects of late suhoor consumption
on short-term high-intensity exercise, with afternoon performance showing the greatest
impact. Although the statistical findings of this study cannot be generalized, the pres-
ence of numerous significant findings and their related effect sizes could have a pair of
potential implications. To begin with, adhering to Fisher’s initial statistical insights [
89
],
the significant findings support future prospective studies in this direction. Additionally,
the beneficial impacts of consuming a late suhoor meal could possibly offer a secure and
efficient strategy to enhance athletes’ short-term high-intensity performance and well-being
indices before the extended period of intermittent fasting during Ramadan. Considering
the beneficial impact of late suhoor intake on enhancing physical performance, athletes and
their coaches may explore the possibility of coordinating optimal suhoor intake strategies
to align with the timing of athletic events, potentially resulting in significant performance
improvements. Aiming for peak performance, this knowledge can be further leveraged to
strategically plan training and competitions. Furthermore, to optimize performance during
Ramadan afternoons, athletes should collaborate with dietitians or sports nutrition experts
to receive personalized guidance tailored to their individual needs, training objectives, and
the demands of their respective sports.
Author Contributions:
Conceptualization, N.S. and H.B.; methodology, N.S.; software, H.B.; valida-
tion, A.A., H.C. and H.B.; formal analysis, A.S.; investigation, N.N.; resources, A.S.; data curation,
N.N.; writing—original draft preparation, H.B.; writing—review and editing, A.A.; visualization,
H.C.; supervision, N.S.; project administration, A.A. All authors have read and agreed to the pub-
lished version of the manuscript.
Funding: This research received no external funding.
Institutional Review Board Statement:
The study was conducted in accordance with the Declaration
of Helsinki and approved by the Physical Activity Research Unit, Sport and Health (UR18JS01),
National Observatory of Sports, Tunisia (The ethics clearance number is: CPP: 0098/2018).
Eur. J. Investig. Health Psychol. Educ. 2023,13 2175
Informed Consent Statement:
Informed consent was obtained from all subjects involved in the study.
Data Availability Statement:
The original contributions presented in the study are included in the
article; further inquiries can be directed to the corresponding author.
Acknowledgments: We are extremely grateful to all the participants who took part in this study.
Conflicts of Interest: The authors declare no conflict of interest.
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