ArticlePDF Available

Abstract and Figures

We aimed to estimate and compare within-day energy balance (WDEB) in athletes with eumenorrhea and menstrual dysfunction (MD) with similar 24-hour energy availability/energy balance (EA/EB). Furthermore, to investigate whether within-day energy deficiency is associated with resting metabolic rate (RMR), body-composition, S-cortisol, estradiol, T 3 , and fasting blood glucose. We reanalyzed 7-day dietary intake and energy expenditure data in 25 elite endurance athletes with eumenorrhea (n=10) and MD (n=15) from a group of 45 subjects where those with disordered eating behaviors (n=11), MD not related to low EA (n=5), and low dietary record validity (n=4) had been excluded. Besides gynecological examination and disordered eating-evaluation, the protocol included RMR-measurement; assessment of body-composition by dual-energy X-ray absorptiometry, blood plasma analysis, and calculation of WDEB in 1-hour intervals. Subjects with MD spent more hours in a catabolic state compared to eumenorrheic athletes; WDEB <0 kcal: 23.0 hour (20.8-23.4) vs 21.1 hour (4.7-22.3), P=0.048; WDEB <-300 kcal: 21.8 hour (17.8-22.4) vs 17.6 hour (3.9-20.9), P=0.043, although similar 24-hour EA: 35.6 (11.6) vs 41.3 (12.7) kcal/kg FFM/day, (P=0.269), and EB:-659 (551) vs-313 (596) kcal/day, (P=0.160). Hours with WDEB <0 kcal and <-300 kcal were inversely associated with RMR ratio (r=-0.487, P=0.013, r=-0.472, P=0.018), and estradiol (r=-0.433, P=0.034, r=-0.516, P=0.009), and positively associated with cortisol (r=0.442, P=0.027, r=0.463, P=0.019). In conclusion, although similar 24-hour EA/EB, the reanalysis revealed that MD athletes spent more time in a catabolic state compared to eumenorrheic athletes. Within-day energy deficiency was associated with clinical markers of metabolic disturbances.
Content may be subject to copyright.
Accepted Article
This article has been accepted for publication and undergone full peer review but has not been
through the copyediting, typesetting, pagination and proofreading process, which may lead to
differences between this version and the Version of Record. Please cite this article as doi:
This article is protected by copyright. All rights reserved.
MS IDA LYSDAHL FAHRENHOLTZ (Orcid ID : 0000-0003-1147-0924)
Article type : Original Article
AUTHORS: Fahrenholtz I.L.1, Sjödin A.1, Benardot D.3, Tornberg Å.B.2, Skouby S.4, Faber J.5,
Sundgot-Borgen J.6, Melin A1.
1Department of Nutrition, Exercise and Sports, University of Copenhagen, Frederiksberg,
Denmark; 2Department of Health Sciences, Lund University, Lund, Sweden, 3Department of
Nutrition, Georgia State University, Atlanta, GA; 4Endocrinological and Reproductive Unit,
Department of Obstetrics/Gynecology, Herlev Hospital, Faculty of Health and Medical Sciences,
University of Copenhagen, Herlev, Denmark; 5Medical and Endocrinological Unit, Herlev
Hospital, Faculty of Health and Medical Sciences, University of Copenhagen, Herlev, Denmark;
6Norwegian School of Sport Sciences, Oslo, Norway.
Anna Katarina Melin: Copenhagen University, Department of Nutrition Exercise and Sports,
Rolighedsvej 26, 1958 Frederiksberg, Denmark. E-mail: Tlf: +46732629714
Accepted Article
This article is protected by copyright. All rights reserved.
RUNNING HEAD: Within-day energy deficiency
We aimed to estimate and compare within-day energy balance (WDEB) in athletes with
eumenorrhea and menstrual dysfunction (MD) with similar 24-hour energy availability/energy
balance (EA/EB). Furthermore, to investigate whether within-day energy deficiency is associated
with resting metabolic rate (RMR), body-composition, S-cortisol, estradiol, T3, and fasting blood
glucose. We reanalyzed 7-day dietary intake and energy expenditure data in 25 elite endurance
athletes with eumenorrhea (n=10) and MD (n=15) from a group of 45 subjects where those with
disordered eating behaviors (n=11), MD not related to low EA (n=5), and low dietary record
validity (n=4) had been excluded. Besides gynecological examination and disordered eating-
evaluation, the protocol included RMR-measurement; assessment of body-composition by dual-
energy X-ray absorptiometry, blood plasma analysis, and calculation of WDEB in 1-hour
intervals. Subjects with MD spent more hours in a catabolic state compared to eumenorrheic
athletes; WDEB <0 kcal: 23.0 hour (20.823.4) vs 21.1 hour (4.722.3), P=0.048; WDEB <-300
kcal: 21.8 hour (17.822.4) vs 17.6 hour (3.920.9), P=0.043, although similar 24-hour EA: 35.6
(11.6) vs 41.3 (12.7) kcal/kg FFM/day, (P=0.269), and EB: -659 (551) vs -313 (596) kcal/day,
(P=0.160). Hours with WDEB <0 kcal and <-300 kcal were inversely associated with RMRratio
(r=-0.487, P=0.013, r=-0.472, P=0.018), and estradiol (r=-0.433, P=0.034, r=-0.516, P=0.009),
and positively associated with cortisol (r=0.442, P=0.027, r=0.463, P=0.019). In conclusion,
although similar 24-hour EA/EB, the reanalysis revealed that MD athletes spent more time in a
catabolic state compared to eumenorrheic athletes. Within-day energy deficiency was associated
with clinical markers of metabolic disturbances.
Accepted Article
This article is protected by copyright. All rights reserved.
KEY WORDS: Energy availability, within-day energy balance, relative energy deficiency,
amenorrhea, catabolism, RMR.
Athletes need an adequate and balanced food and fluid intake that provides nutritional support
for optimal adaption to training and optimal performance, but also for preventing illness and
injuries. An appropriate energy intake is the cornerstone of the athlete’s diet because it supports
optimal body function, determines the capacity for intake of macronutrient and micronutrients,
and assists in manipulating body composition1,2. Female athletes focusing on leanness, however,
have been reported to have an increased risk of developing restricted eating behaviors and low
energy availability (EA)3,4,5. Low EA with or without disordered eating (DE) behavior is related
to endocrine alterations leading to several health and performance impairing conditions including
menstrual dysfunction (MD), gastrointestinal problems, impaired bone health, and increased
injury risk4,5,6 . The hormonal synthesis and increased luteal phase thermogenesis are energy
consuming processes7, and the energy metabolism at rest (RMR) therefore changes up to 10%
during the menstrual cycle, with peaks during the late luteal phase or the early follicular phase8.
MD may consequently result in lower energy needs in a physiological adaptation to insufficient
energy intakes. Most female athletes with long-term energy deficiency are reported to maintain a
steady body weight and body composition within the normal range, independent of their
reproductive function9. Therefore, other metabolic mechanisms may be involved, such as a
reduction in RMR and/or non-exercise activity thermogenesis (NEAT)10, as well as in increased
work-load efficiency11,12.
Traditionally, the energy status of athletes is evaluated in blocks of 24-hours as either energy
balance (EB) (energy intake total energy expenditure) or EA (energy intake exercise energy
Accepted Article
This article is protected by copyright. All rights reserved.
expenditure)13. Experimental studies have demonstrated a causal relationship between low EA
and the endocrine perturbations related to MD14,15,16. However, consistent with many other
studies6,17,18 we have previously reported similar 24-hour EA and EB in this group of elite
athletes with MD vs eumenorrheic athletes12,19.
The traditional 24-hour view on human thermodynamics has been criticized for failing to
account for the endocrine responses that act on real-time changes in energy intake and
expenditure20. Therefore, a new view on EB, where energy intake and energy expenditure are
assessed in 1-hour intervals, has been proposed to be more appropriate20. Within-day energy
deficiency (WDED) has previously been associated with an unfavorable body composition in
female elite gymnasts and runners, presumably related to both an adaptive reduction in RMR21,
and endocrine responses that favor muscle catabolism and fat gain20,21. Therefore, a restrictive
eating behavior, resulting in more hours spent in energy deficiency, may have the opposite of the
desired effect on athletes’ body composition. A desirable range of EB of ± 300 kcal has been
suggested, since 300 kcal corresponds to the predicted amount of liver glycogen for female
athletes21. Exceeding the threshold of EB below -300 kcal, could potentially accelerate
biochemical pathways associated with energy deficiency20 and compromise brain glucose
availability and thereby normal gonadotropin-releasing hormone (GnRH) neuron activity and
luteinizing hormone (LH) pulsatility7,13.
According to the International Olympic Committee consensus statement, WDED is a possible
contributor to the reproductive and metabolic alterations associated with relative energy
deficiency4. However, these links have not been demonstrated in athletes. Hence, we wanted to
investigate if female elite endurance athletes with MD with similar reported 24-hour EB and EA
as eumenorrheic athletes spend more time in a catabolic state and have a larger magnitude of
Accepted Article
This article is protected by copyright. All rights reserved.
WDED compared to eumenorrheic athletes. Furthermore, it was our intent to investigate if
WDED is associated with suppressed RMR and endocrine alterations in these athletes.
Permission to undertake the study was provided by the Swedish and Danish Confederation of
Sports, Team Denmark, the Data Inspectorate, and the Regional Ethical committees, both in
Sweden and Denmark (nos. 2011/576 and H-4-2011-096, respectively). The protocol was
registered at
We reanalyzed data concerning 7-day energy intake and energy expenditure from a previous
study19, and the recruitment and methods used have previously been described in detail12.
Athletes recruited and included in the subject pool were endurance athletes on a national team or
competitive club level between the age of 18 to 38 years, and training a minimum of 5 times per
week. All subjects had been informed orally, and in writing, of all study procedures and signed
an informed consent form. Data were collected on 2 consecutive days that were followed by a 7-
day recording period in the athletes’ normal environment. The timing of the examination and
registration period was planned individually for each subject to choose a period that reects their
habitual food habits and exercise regimes. Menstruating athletes were examined in the early
follicular phase.
The first day consisted of anthropometric assessment [body weight and height, dual-energy X-
ray absorptiometry (DXA) to determine fat free mass (FFM) and fat mass (FM)], and
examinations of reproductive function (a transvaginal ultrasound examination by an experienced
gynecologist, sex hormone status, and a retrospective menstrual history using LEAF-Q22).
Subjects were classied with eumenorrhea (menstrual cycles of 28 days ±7 days and sex
hormones within the normal range), functional hypothalamic oligomenorrhea (menstrual cycles
Accepted Article
This article is protected by copyright. All rights reserved.
>35 days where other causes than hypothalamic suppression had been ruled out), amenorrhea
(either primary: no menarche after 15 years of age, or secondary: absence of at least 3
consecutive menstrual cycles where other causes than hypothalamic suppression had been ruled
out), or other MD not related to energy deficiency. The second day included examinations of
aerobic capacity and assessment of DE assessed by the Eating Disorder Inventory23. The
incremental test reflected heart rates being linearly correlated with O2 consumption at increasing
workloads (r = 0.94, 95% CI 0.93-0.96), providing the basis for the individual regression lines
and later calculations of exercise-associated energy expenditure. RMR was assessed after an
overnight fast, using a ventilated open hood system (Oxycon Pro 4, Jeager, Germany). Blood
was drawn from an antecubital vein in fasted subjects between 8:30 and 8:50 by a qualified bio-
After the 2 examination days, subjects weighed and registered food and beverage intake during a
consecutive 7-day period using a digital kitchen scale (Exido 246030 Kitchen Scale, Gothenburg,
Sweden). Heart rate monitors (Polar RS400®,Kempele, Finland) and training logs were used to
assess energy expenditure during exercise and bicycle transportation, while subjects wore an
accelerometer (ActiGraph GT3X®, Pensacola, FL, USA) on the hip (except during showering,
swimming, bicycle transportation, and training) for the assessment of NEAT. Exercise energy
expenditure for swim sessions was calculated based on mean heart rate obtained from the
remaining training sessions. NEAT was calculated for each waking hour using the data analysis
software ActiLife 6 (ActiGraph). The nutrient analysis program MadlogVita (Madlog ApS,
Kolding, Denmark) and Dietist XP (Kost och Näringsdata AB, Bromma, Sweden) were used to
analyze food records. The daily numbers of meals and snacks were counted. Dietary analysis was
performed in 25 subjects after excluding 5 due to clinically verified MD other than functional
Accepted Article
This article is protected by copyright. All rights reserved.
hypothalamic amenorrhea/oligomenorrhea, 11 due to DE, and 4 due to low validity using the
equation described by Black24.
EA was calculated as total energy intake minus exercise energy expenditure (mean/24hour)
expressed in relation to FFM. The athletes themselves defined and registered every training
The hourly within-day energy balance (WDEB) was calculated as follows: energy intake total
energy expenditure, where total energy expenditure represents exercise energy expenditure +
predicted exercise post oxygen consumption (EPOC) + diet induced thermogenesis (DIT) +
NEAT + RMR. WDED variables were used according to Deutz, et al.21: total hours with energy
deficit (unadapted WDEB < 0 kcal), hours spent in energy deficit exceeding 300 kcal (unadapted
WDEB < -300 kcal), and largest single-hour energy deficit (Figure 1). DIT was defined as 10%
of energy intake and the equation 175.9·T·e -T/1.3 presented by Reed and Hill25 was used to
calculate DIT the first 6 hours after each meal/snack. Based on results from studying young
active eumenorrheic women26, EPOC was calculated as 5% of exercise energy expenditure the
first hour post-exercise plus 3% of exercise energy expenditure the second hour post-exercise.In
order to control for the problem of potential underestimation of energy requirements, the
unadapted/predicted RMR, instead of measured RMR, was used when calculating total energy
expenditure. Hence, the aim was to calculate the unadapted EB. The hourly predicted RMR was
calculated using the Cunningham equation: RMR, kcal/hour = (500 + (22· FFM [kg])
kcal/day)/24 hours/day. The RMRratio was calculated as measured RMR/predicted RMR.
Sleeping metabolic rate was calculated as 90% of RMR and used instead of RMR during
sleeping hours. The starting point for the calculation of WDEB was at midnight on the first day
of food recording and was calculated as the mean energy intake of the last daily meal or snack
Accepted Article
This article is protected by copyright. All rights reserved.
minus mean total energy expenditure in the time interval following the mean meal/snack
consumption. WDEB was calculated continuously for the 7 days of registration.
Statistical calculations were performed using RStudioTM (version 0.99.879) with a two-tailed
significance level of < 0.05. All data sets were tested for normality and homogeneity of variance
before statistical hypothesis tests were performed. Normally distributed data were summarized as
mean and standard deviation (SD), and non-normally distributed data as median and interquartile
range (IQ 25 and IQ 75 percentiles). Differences between MD and eumenorrheic subjects were
investigated using unpaired Student’s t-test for normally distributed data and the Wilcoxon rank-
sum test for non-parametric data. Pearson’s correlation coefficient and Spearman’s rank
correlation coefficient were calculated to investigate associations between WDED variables and
continuous outcomes for normally and non-normally distributed data, respectively.
Subject characteristics are presented in Table 1. As earlier reported19 15 of 25 subjects (60%)
were diagnosed with MD and there were no differences in age, height, body weight or BMI
between subjects characterized by reproductive function. MD subjects had 19% lower FM and
14% lower relative FM compared to eumenorrheic subjects, although there were no differences
in training volume or exercise capacity.
There were no differences in any of the energy expenditure components between eumenorrheic
and MD subjects, but subjects with MD had lower RMRratio compared to eumenorrheic subjects
(Table 2).
Accepted Article
This article is protected by copyright. All rights reserved.
There was no difference in 24-hour EA [35.6 (11.6) vs 41.3 (12.7) kcal/kg FFM/day, P = 0.269)]
or EB [-659 (551) vs -313 (596) kcal/day, P = 0.160] between subjects with MD vs those with
eumenorrhea. Subjects with MD spent more time with EB < 0 kcal (P = 0.048) and < -300 kcal
(P = 0.043) compared to eumenorrheic subjects (Table 3). Subjects with MD had significantly
more meals/snacks per day compared to eumenorrheic subjects [6.5 (1.0) vs 5.5 (0.8) meals/day,
P = 0.014]. We found no association between meal frequency and energy intake, but time spent
in energy deficiency was positively associated with meal frequency (r = 0.398, P = 0.0485).
A sub analysis excluding oligomenorrheic subjects, showed a more pronounced difference
between amenorrheic (n = 11) and eumenorrheic subjects in EB < 0kcal [23.3 (22.7 23.6) hours
vs 21.1 (4.7 22.3) hours, (P = 0.009)] and < -300 kcal [22.3 (21.6 22.7) hours vs 17.6 (3.9
20.9) hours (P = 0.007)].
The regression analysis showed that the more hours spent with EB < 0 kcal and < -300 kcal, the
lower the RMRratio and estrogen and the higher the cortisol levels (Table 4). In addition, smaller
magnitudes of hourly energy deficits (closer to 0 kcal) were associated with higher estrogen
Although assessed athletes had similar 24-hour EA and EB, this reanalysis revealed that those
with MD spent significantly more time in a catabolic state compared to eumenorrheic athletes. In
addition, the more time the athletes spent in a catabolic state the lower the RMRratio and estrogen,
and the higher the cortisol levels.
Previously, Deutz and colleges21 investigated WDEB in female elite athletes. The present study
is, however, the first to include its relationship with reproductive function and metabolic
Accepted Article
This article is protected by copyright. All rights reserved.
adaptations. In contrast to Deutz and collaborators, we found no association between WDED and
body composition.
The menstrual cycle is an energy demanding process that relies on adequate availability of
energy and glucose for optimal LH pulsatility13. Randomized controlled trials have demonstrated
a disruption of the normal sex hormone secretion in regularly menstruating women14,15,16 when
manipulating EA, and it is well established that relative energy deficiency increases the risk of
MD4. However, in line with many earlier studies6,17,18 we could not demonstrate significant
differences in 24-hour EB or EA between MD and eumenorrheic athletes. Several researchers
have suggested that a plausible difference among women is their susceptibility to energy
restriction3,17,18,19,27, which might contribute to the explanation for similar 24-hour EB and EA in
athletes with and without MD. An additional factor could be that the 24-hour assessment of
energy status masks periods with energy deficiency substantial enough to maintain reproductive
dysfunction. When calculating the traditional 24-hour EB or EA light training days may have a
compensatory effect on the mean 24-hour value. In contrast, the WDEB calculation is
cumulative and takes into account potential energy deficiencies or access from previous days.
During the follicular phase, pulses of GnRH, responsible of the release of LH and follicle
stimulating hormone from the anterior pituitary, occur at hourly intervals7, and animal studies
suggest that the reproductive function is responsive to hourly changes in metabolic fuel
oxidation28. Both energy expenditure and energy intake fluctuate greatly during waking hours,
providing a natural within-day variation in EA and EB in athletes13. Although the athletes in the
present study, independently of reproductive function, spent the majority of the day in an energy
deficient state, the athletes with MD spent 24% more hours in EB < -300 kcal compared to
eumenorrheic athletes, providing a potentially more profound catabolic state in female athletes
Accepted Article
This article is protected by copyright. All rights reserved.
with MD. It is possible that amenorrheic athletes spend a greater proportion of time during the
day without sufficient blood glucose available, which would negatively impact normal
functioning of the hypothalamic-pituitary-gonadal-axis. There was however, no difference in the
largest hourly deficit between groups, which may indicate that large energy deficit if transient do
not disturb reproductive function. The large variations within the eumenorrhea group illustrate
that some athletes classified with regular menstrual cycles also had prolonged deficits. Loucks
and Thuma15 demonstrated that women with shorter luteal phase (11 days) are more susceptible
to energy deficiency in terms of endocrine alterations compared to women with longer luteal
phases (12-14 days). As discussed by the authors, women that by nature have a slightly shorter
luteal phase may be of an increased risk of developing MD when exposed to energy deficiency15.
Thus, the eumenorrheic athletes with a high number of catabolic hours in the present study may
be women with a more robust reproductive function. On the other hand, it is unknown whether
these athletes may have had subclinical MDs associated with energy deficiency such as
anovulation or luteal phase abnormality (luteal length < 10 days or inadequate/low progesterone
concentration6). This condition is diagnosed by measuring daily ovarian steroid hormones in
blood or urine over a full menstrual cycle9. Indeed, an incidence of 79% of luteal phase
deficiency has been reported among recreational, regularly menstruating runners in a 3-months
sample6. In the sedentary control group, 90% of all menstrual cycles were ovulatory, whereas in
the runners only 45% were ovulatory. Another possible explanation is related to the cross-
sectional design where measurements only provide a snapshot over one week and not necessarily
the long-term consequences of energy deficiency, which is necessary to develop MD. In this
perspective, it is important also to evaluate more acute consequences of energy deficiency such
as suppressed RMR as we did in the present study, where we found WDED to be associated with
Accepted Article
This article is protected by copyright. All rights reserved.
lower RMRratio. Several studies have reported reduced RMR in female athletes with MD
compared to eumenorrheic athletes12,29,30,31, and our results support previous studies suggesting
that the RMRratio may be used as a useful marker for identifying athletes with energy
deficiency5,12,18,27. Consequently, when calculating EB in athletes with insufficient energy intake
and MD, using measured RMR might result in a more neutral EB, underestimating the degree of
energy deficiency13,32.
We found WDED to be associated with higher cortisol and lower estrogen levels and a trend
suggesting lower T3 levels, as signs of biological stress. LH pulsatility, T3 and cortisol levels are
regulated by brain glucose availability13 hence extensive periods in an energy deficient state are
likely to cause these hormonal alterations.
The present study found no association between body composition and WDED. This is in
contrast to an earlier study assessing elite female runners and gymnasts, where hours with EB <
0 kcal, and with EB < -300 kcal were positively associated with relative fat mass (r = 0.285, P =
0.03 and r = 0.407, P < 0.01, respectively), and the largest energy deficit was negatively
associated with relative fat mass (r = -0.378, P < 0.01)21. It has been suggested that an increased
meal frequency33, and an increased protein intake of 1.82.0 g/kg/day34 during hypocaloric
conditions might have an anti-catabolic effect on FFM in athletes. Hence, the high meal
frequency and high protein intake [2.1 (0.4) g/kg/day]19 observed among these MD athletes
might potentially explain the maintenance of FFM despite profound WDED.
Accepted Article
This article is protected by copyright. All rights reserved.
Since this is an observational study, it is not able to demonstrate a causal relationship between
WDED and reproductive function or metabolic adaptations. As reviewed by Burke1, studies
using self-reported food diaries are always challenged by errors of validity and reliability.
Although subjects with DE behavior and suspected under reporters were excluded, there is a risk
for not identifying all subjects miss-reporting dietary intake24. Despite possible systemic errors,
these are presumed to be equally distributed between groups and the differences found are
therefore still valid even if energy expenditure has been overestimated and/or energy intake has
been underestimated. Due to the small sample size and several correlation analyses made, our
results should primarily be seen exploratory. Nevertheless, our findings that MD athletes spent
significantly more time in a catabolic state compared to eumenorrheic athletes although similar
24-hour EA and EB assessment is interesting and was associated with clinical markers of energy
suppression e.g. lower RMR. Finally, the energy deficiency cut-off -300 kcal, suggested by
Deutz, et al.21, is theoretically founded and may vary depending on different individual factors,
including body weight35. Lack of identification of subclinical MD are also a limitation of the
study. As other calculation methods evaluating athletes’ energy status, the WDEB calculation
entails uncertainties. Nevertheless, the 24-hour assessments, although more practical, may be too
simple to detect the differences in energy deficiency between MD and eumenorrheic athletes.
Practical implications
Based on the results from the present and other studies6,17,18, a continuous view on energy status
evaluated in smaller time blocks may be more appropriate than the 24-hour assessments.
Accepted Article
This article is protected by copyright. All rights reserved.
However, the method is time-consuming and requires equipment capable of assessing energy
expenditure in minor blocks, and participants must carefully note the timing of energy intake and
energy expenditure. Nonetheless, our results emphasize important considerations for
practitioners of the potential limitations of the 24-hour assessment. A high meal frequency may
be necessary for athletes to ensure adequate energy intake35,36 and to improve WDEB. However,
the paradoxical finding of a positive association between WDED and meal frequency, suggests
that a high meal frequency does not improve WDEB in athletes eating mainly low energy dense
foods as earlier reported in this population, especially among MD athletes19. Therefore, other
dietary characteristics, behavioral attitudes and taboos towards certain foods, including
carbohydrate-rich foods, fats, and energy containing beverages needs to be evaluated when
counseling athletes at risk for energy deficiency.
The present study demonstrates that the traditional 24-hour assessment of EB and EA may not be
sufficient for detecting athletes in an energy deficient state and a continuous view on EB may be
more appropriate. This is the first study to investigate the relationship between WDED and
clinically verified MD as well as metabolic suppression related to energy deficiency. Therefore,
more studies are needed, preferably with larger sample size in order to be able to differentiate
between subjects with oligomenorrhea and amenorrhea, but also subjects with subclinical MD
(anovulation and short luteal phase defect).
Accepted Article
This article is protected by copyright. All rights reserved.
We thank Drs Mubeena Aziz and Katrine Haahr at Herlev Hospital for performing gynecological
examinations; Anders Johansson, Lund University, and Ulla Kjærulff-Hansen, Herlev Hospital,
for assisting with blood sampling; Fiona Koivola, Lund University, for assisting during testing,
and Hanne Udengaard, Herlev Hospital, for logistics assistance. Finally, we highly appreciate the
extraordinary cooperation of the athletes participating in this study and the support of the
Swedish and Danish national sports federations and Team Denmark.
This study was funded by research grants from the Faculty of Science, University of
Copenhagen, World Village of Women Sports Foundation and Arla Foods Ingredients.
The results of the present study are presented clearly, honestly, and without fabrication,
falsification, or inappropriate data manipulation. Dan Benardot is the inventor and scientific
advisor of NutriTiming®, a software package that analyzes hourly EB. This software program,
however, was not used for this study.
Accepted Article
This article is protected by copyright. All rights reserved.
1. Burke LM. Energy needs of athletes. Can J Appl Physiol. 2001;26:S202-19.
2. Thomas DT, Erdman KA, Burke LM. Position of the Academy of Nutrition and
Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition
and Athletic Performance. J Acad Nutr Diet. 2016;116:501-28.
3. Manore MM. Dietary recommendations and athletic menstrual dysfunction. J Sports Sci.
4. Mountjoy M, Sundgot-Borgen J, Burke L, et al. The IOC consensus statement: beyond
the Female Athlete Triad Relative Energy Deficiency in Sport (RED-S). Brit J Sports
Med. 2014;48:491-7.
5. Nattiv A, Loucks AB, Manore M, Sanborn CF, Sundgot-Borgen J, Warren MP. The
female athlete triad. Med Sci Sports Exer. 2007;39:1867-82.
6. De Souza MJ, Miller BE, Loucks AB, et al. High Frequency of Luteal Phase Deficiency
and Anovulation in Recreational Women Runners: Blunted Elevation in Follicle-
Stimulating Hormone Observed during Luteal-Follicular Transition 1. J Clin Endocrinol
Metab. 1998;83:4220-32.
7. Harber VJ. Energy balance and reproductive function in active women. Can J Appl
Physiol. 2004;29:48-58.
8. Henry CJK, Lightowler HJ, Marchini J. Intra-individual variation in resting metabolic
rate during the menstrual cycle. Br J Nutr. 2003;89:811-17.
9. Redman LM, Loucks AB. Menstrual disorders in athletes. Sports Med. 2005;35:747-55.
Accepted Article
This article is protected by copyright. All rights reserved.
10. Redman LM, Heilbronn LK, Martin CK, et al. Metabolic and behavioral compensations
in response to caloric restriction: implications for the maintenance of weight loss. PloS
One. 2009;4:e4377.
11. Goldsmith R, Joanisse DR, Gallagher D, et al. Effects of experimental weight
perturbation on skeletal muscle work efficiency, fuel utilization, and biochemistry in
human subjects. Am J Physiol Regul Integr Comp Physiol. 2010;298:R79-88.
12. Melin A, Tornberg ÅB, Skouby S, et al. Energy availability and the female athlete triad
in elite endurance athletes, Scand J Med Sci Sports. 2014;25:610-22.
13. Loucks AB. Energy balance and energy availability. In: Maughan, RJ, editor. The
Encyclopedia of Sports Medicine, Energy and Macronutrients. International Olympic
Committee. 1 ed. John Wiley & Sons, Ltd; 2014. p. 72-87.
14. Loucks AB, Heath EM. Dietary restriction reduces luteinizing hormone (LH) pulse
frequency during waking hours and increases LH pulse amplitude during sleep in young
menstruating women. J Clin Endocrinol Metab. 1994;78:910-15.
15. Loucks AB, Thuma JR. Luteinizing hormone pulsatility is disrupted at a threshold of
energy availability in regularly menstruating women. J Clin Endocrinol Metab.
16. Olson BR, Cartledge T, Sebring N, Defensor R, Nieman L. Short-term fasting affects
luteinizing hormone secretory dynamics but not reproductive function in normal-weight
sedentary women. J Clin Endocrinol Metab. 1995;80:1187-93.
17. Guebels CP, Kam LC, Maddalozzo GF, Manore MM. Active women before/after an
intervention designed to restore menstrual function: Resting metabolic rate and
Accepted Article
This article is protected by copyright. All rights reserved.
comparison of four methods to quantify energy expenditure and energy availability. Int J
Sport Nutr Exerc Metab. 2014;24:37-46.
18. Schaal K, Van Loan MD, Casazza GA. Reduced Catecholamine Response to Exercise in
Amenorrheic Athletes. Med Sci Sports Exerc. 2001;43:34-43.
19. Melin A, Tornberg ÅB, Skouby S, et al. Lowenergy density and high fiber intake are
dietary concerns in female endurance athletes. Scand J Med Sci Sports. 2015;26:1060-71.
20. Benardot D. Energy Thermodynamics Revisited: Energy intake strategies for optimizing
athlete body composition and performance. Pensar en Movimiento. 2013;11:1-13.
21. Deutz RC, Benardot D, Martin DE, Cody MM. Relationship between energy deficits and
body composition in elite female gymnasts and runners. Med Sci Sport Exerc.
22. Melin A, Tornberg ÅB, Skouby S, et al. The LEAF questionnaire: a screening tool for the
identification of female athletes at risk for the female athlete triad, Brit J Sports Med.
23. Garner DM. Eating Disorder Inventory-3. Professional Manual. Par. Inc. 2004. p. 1-213.
24. Black AE. Critical evaluation of energy intake using the Goldberg cut-off for energy
intake: basal metabolic rate. A practical guide to its calculation, use and limitations. Int J
Obes Relat Metab Disord. 2000;24:1119-30.
25. Reed GW, Hill JO. Measuring the thermic effect of food. Am J Clin Nutr. 1996;63:164-9.
26. Phelain JF, Reinke E, Harris MA, Melby CL. Postexercise energy expenditure and
substrate oxidation in young women resulting from exercise bouts of different intensity. J
Am Coll Nutr. 1997;16:140-6.
Accepted Article
This article is protected by copyright. All rights reserved.
27. Gibbs JC, Williams NI, Scheid JL, Toombs RJ, De Souza MJ. The association of a high
drive for thinness with energy deficiency and severe menstrual disturbances:
confirmation in a large population of exercising women. Int J Sport Nutr Exerc Metab.
28. Wade GN, Jones JE. Neuroendocrinology of nutritional infertility. Am J Physiol Regul
Integr Comp Physiol. 2004;287:R1277-96.
29. O'Donnell E, Harvey PJ, De Souza MJ. Relationships between vascular resistance and
energy deficiency, nutritional status and oxidative stress in oestrogen deficient physically
active women. Clin Endocrinol. 2009;70: 294-302.
30. Scheid JL, Williams NI, West SL, VanHeest JL, De Souza MJ. Elevated PYY is
associated with energy deficiency and indices of subclinical disordered eating in
exercising women with hypothalamic amenorrhea. Appetite. 2009;52:184-192.
31. Vanheest JL, Rodgers CD, Mahoney CE, De Souza MJ. Ovarian suppression impairs
sport performance in junior elite female swimmers. Med Sci Sports Exerc. 2014;46:156-
32. Loucks AB, Kiens B, Wright HH. Energy availability in athletes. J Sports Sci.
33. Iwao S, Mori K, Sato Y. Effects of meal frequency on body composition during weight
control in boxers. Scand J Med Sci Sports. 1996;6:265-72.
34. Phillips SM, Van Loon LJ. Dietary protein for athletes: from requirements to optimum
adaptation. J Sports Sci. 2011;29:S29-38.
35. Benardot D. Timing of energy and fluid intake: New concepts for weight control and
hydration. ACSM's Health & Fitness Journal. 2007;11:13-19.
Accepted Article
This article is protected by copyright. All rights reserved.
36. Hawley J, Burke L. Effect of meal frequency and timing on physical performance, Br J
Nutr. 1997;77:S91-103.
Figure 1. Graphical depiction of how WDEB values were determined. Assessed values
include number of hours > 300 kcal; hours < 300 kcal; hours > 0 kcal; hours < 0 kcal
Modified from Benardot20. In contrast to the traditional method comparing energy intake with
total energy expenditure or exercise energy expenditure in 24-hour intervals, WDEB assesses
time and magnitude deviations from the predicted EB. Horizontal axis: energy status (kcal);
vertical axis: time course throughout the day (hours). The given example illustrates 5 hours with
WDEB > 0 kcal, 19 hours with WDEB < 0 kcal, 2 hours with WDEB > 300 kcal, and 7 hours
with WDEB < -300. Largest surplus is +426 kcal and largest deficit is -829 kcal. The 24-hour
energy balance is +19 kcal. Abbreviation: WDEB: within-day energy balance.
Accepted Article
This article is protected by copyright. All rights reserved.
Table 1. Description of subjects characterized by reproductive function
All Eumenorrhea MD P-value1
(n=25) (n=10) (n=15)
Age (years) 26.6 (5.6) 26.8 (4.6) 26.5 (6.3) 0.910
Height (cm) 169.9 (5.8) 170.0 (5.8) 168.1 (5.9) 0.081
Body weight (kg) 58.8 (7.3) 61.2 (8.2) 57.1 (6.4) 0.173
BMI (kg/m2) 20.6 (2.0) 21.2 (2.3) 20.2 (1.6) 0.228
Body fat (kg) 11.8 (3.1) 13.3 (3.1) 10.8 (2.8) 0.049
Body fat (%) 19.8 (3.6) 21.7 (3.3) 18.6 (3.3) 0.034
Fat free mass (kg) 46.0 (43.0 50.7) 49.2 (44.3 50.5) 46.0 (42.9 49.8) 0.482
Exercise (hours/week) 12.0 (4.4) 11.1 (2.9) 12.7 (5.1) 0.363
VO2peak (ml/kg/min) 54.5 (6.4) 53.0 (5.7) 55.5 (6.9) 0.354
Data are presented as mean (SD) for normally distributed data and as median and interquartile range (25-
75) for non-normally data. Abbreviations: BMI: body mass index, MD: menstrual dysfunction, VO2peak:
maximal oxygen uptake. 1) Difference between eumenorrheic and MD subjects.
Accepted Article
This article is protected by copyright. All rights reserved.
Table 2. Energy expenditure characterized by reproductive function
All Eumenorrhea MD P-value1
(n=25) (n=10) (n=15)
Total EE2 (kcal/day) 3247 (553) 3205 (443) 3276 (628) 0.761
DIT (kcal/day) 271 (44) 287 (54) 261 (34) 0.189
Exercise EE (kcal/day) 968 (571) 942 (295) 985 (568) 0.828
EPOC (kcal/day) 80 (38) 75 (24) 83 (46) 0.653
NEAT (kcal/day) 446 (147) 400 (74) 446 (177) 0.156
pRMR (kcal/hour) 64 (5) 65 (4) 63 (5) 0.498
pSMR (kcal/hour) 58 (5) 58 (4) 57 (5) 0.516
mRMR (kcal/hour) 57 (7) 60 (6) 55 (7) 0.063
RMRratio 0.89 (0.07) 0.93 (0.05) 0.87 (0.07) 0.033
Data are presented as mean (SD). Abbreviations: DIT: diet induced thermogenesis, EE: energy
expenditure, EPOC: excess post-exercise oxygen consumption, MD: menstrual dysfunction, mRMR:
measured resting metabolic rate, pRMR: predicted resting metabolic rate, pSMR: predicted sleeping
metabolic rate. 1) Difference between eumenorrheic and MD subjects. 2) Unadapted total energy
Accepted Article
This article is protected by copyright. All rights reserved.
Table 3. Within-day energy deficiency characterized by reproductive function
All Eumenorrhea MD P-value1
(n=25) (n=10) (n=15)
WDEB < 0 kcal
(hours/day) 22.1 (19.7 23.3) 21.1 (4.7 22.3) 23.0 (20.8 23.4) 0.048
WDEB <-300 kcal
(hours/day) 21.3 (15.7 22.3) 17.6 (3.9 20.9) 21.8 (17.8 22.4) 0.043
Largest hourly deficit
(kcal) -2626 (2352) -1793 (2360) -3181 (2253) 0.159
Data are presented as mean (SD) for normally distributed data and as median and interquartile range (25-
75) for non-normally distributed data. Abbreviations: MD: menstrual dysfunction, WDEB: within-day
energy balance. 1) Difference between eumenorrheic and MD subjects.
Table 4. Associations between within-day energy deficiency and markers for catabolic state
Hours with WDEB < 0 kcal Hours with WDEB <-300 kcal Largest hourly deficit1
r P-value r P-value r P-value
RMRratio -0.487 0.013 -0.472 0.018 0.310 0.132
Body fat (%) -0.313 0.128 -0.337 0.100 0.023 0.913
Cortisol 0.442 0.027 0.463 0.019 -0.297 0.111
Estradiol -0.433 0.034 -0.516 0.009 0.505 0.012
T3 -0.360 0.078 -0.264 0.203 0.287 0.164
Glucose -0.350 0.086 -0.365 0.073 0.202 0.333
All subjects (n=25) were included in the correlation analysis. Abbreviations: RMR: resting metabolic rate,
WDEB: within-day energy balance. 1)values recorded as negative numbers.
Accepted Article
This article is protected by copyright. All rights reserved.
... Following birth, significant prepubertal differences exist between the structure and function of other organ systems in boys and girls, which are eventually further emphasized by hormone activity and driven by a sex-specific reactivity to environmental stimuli, including nutrients and the diet in general. Although difficult to separate from the hormonal influences, important sex differences exist in mitochondrial function [14][15][16], substrate utilization, and insulin sensitivity [17][18][19][20][21][22][23][24] [45,46]{Sims, 2008 #55, [47][48][49][50][51][52][53], appetite control [54][55][56][57][58][59], and energy availability and endocrine function [60][61][62][63][64][65]. ...
... EA is likely to vary between training days (as a function of EEE), and it is the within-day periods of low energy intake over 24-hours that are associated with negative health indices and body composition changes despite optimal daily EA values [62,152]. Research has demonstrated that females with menstrual dysfunction exhibit greater elevations in cortisol and decreases in RMR and estradiol the longer they delay nutrition intake, post-exercise [62]. ...
... EA is likely to vary between training days (as a function of EEE), and it is the within-day periods of low energy intake over 24-hours that are associated with negative health indices and body composition changes despite optimal daily EA values [62,152]. Research has demonstrated that females with menstrual dysfunction exhibit greater elevations in cortisol and decreases in RMR and estradiol the longer they delay nutrition intake, post-exercise [62]. Of importance, nutrient timing has been proposed to have a significant impact on attenuating increasing health, exercise training, and recovery implications [153]. ...
Full-text available
Based on a comprehensive review and critical analysis of the literature regarding the nutritional concerns of female athletes, conducted by experts in the field and selected members of the International Society of Sports Nutrition (ISSN), the following conclusions represent the official Position of the Society: 1. Female athletes have unique and unpredictable hormone profiles, which influence their physiology and nutritional needs across their lifespan. To understand how perturbations in these hormones affect the individual, we recommend that female athletes of reproductive age should track their hormonal status (natural, hormone driven) against training and recovery to determine their individual patterns and needs and peri and post-menopausal athletes should track against training and recovery metrics to determine the individuals' unique patterns. 2. The primary nutritional consideration for all athletes, and in particular, female athletes, should be achieving adequate energy intake to meet their energy requirements and to achieve an optimal energy availability (EA); with a focus on the timing of meals in relation to exercise to improve training adaptations, performance, and athlete health. 3. Significant sex differences and sex hormone influences on carbohydrate and lipid metabolism are apparent, therefore we recommend first ensuring athletes meet their carbohydrate needs across all phases of the menstrual cycle. Secondly, tailoring carbohydrate intake to hormonal status with an emphasis on greater carbohydrate intake and availability during the active pill weeks of oral contraceptive users and during the luteal phase of the menstrual cycle where there is a greater effect of sex hormone suppression on gluconogenesis output during exercise. 4. Based upon the limited research available, we recommend that pre-menopausal, eumenorrheic, and oral contraceptives using female athletes should aim to consume a source of high-quality protein as close to beginning and/or after completion of exercise as possible to reduce exercise-induced amino acid oxidative losses and initiate muscle protein remodeling and repair at a dose of 0.32-0.38 g·kg-1. For eumenorrheic women, ingestion during the luteal phase should aim for the upper end of the range due to the catabolic actions of progesterone and greater need for amino acids. 5. Close to the beginning and/or after completion of exercise, peri- and post-menopausal athletes should aim for a bolus of high EAA-containing (~10 g) intact protein sources or supplements to overcome anabolic resistance. 6. Daily protein intake should fall within the mid- to upper ranges of current sport nutrition guidelines (1.4-2.2 g·kg-1·day-1) for women at all stages of menstrual function (pre-, peri-, post-menopausal, and contraceptive users) with protein doses evenly distributed, every 3-4 h, across the day. Eumenorrheic athletes in the luteal phase and peri/post-menopausal athletes, regardless of sport, should aim for the upper end of the range. 7. Female sex hormones affect fluid dynamics and electrolyte handling. A greater predisposition to hyponatremia occurs in times of elevated progesterone, and in menopausal women, who are slower to excrete water. Additionally, females have less absolute and relative fluid available to lose via sweating than males, making the physiological consequences of fluid loss more severe, particularly in the luteal phase. 8. Evidence for sex-specific supplementation is lacking due to the paucity of female-specific research and any differential effects in females. Caffeine, iron, and creatine have the most evidence for use in females. Both iron and creatine are highly efficacious for female athletes. Creatine supplementation of 3 to 5 g per day is recommended for the mechanistic support of creatine supplementation with regard to muscle protein kinetics, growth factors, satellite cells, myogenic transcription factors, glycogen and calcium regulation, oxidative stress, and inflammation. Post-menopausal females benefit from bone health, mental health, and skeletal muscle size and function when consuming higher doses of creatine (0.3 g·kg-1·d-1). 9. To foster and promote high-quality research investigations involving female athletes, researchers are first encouraged to stop excluding females unless the primary endpoints are directly influenced by sex-specific mechanisms. In all investigative scenarios, researchers across the globe are encouraged to inquire and report upon more detailed information surrounding the athlete's hormonal status, including menstrual status (days since menses, length of period, duration of cycle, etc.) and/or hormonal contraceptive details and/or menopausal status.
... One such possible indicator is RMR ratio , calculated as the quotient of an individual's measured RMR versus that predicted using an equation based on contributing variables such as age, height, body mass, and FFM [5]. Numerous investigations (but not all [107,[115][116][117][118]) have observed relationships between RMR ratio and associated markers of EA in active individuals, including 7-day EA [119]; within-day EB [120,121]; menstrual/estrogen status [119,120,[122][123][124][125][126]; volumetric bone characteristics [127] and formation markers [122]; alterations in TT 3 concentrations [122,124,125,128,129]; and in other hormones such as ghrelin, leptin, peptide YY, and insulin-like growth factor-1 [123,125,129,130]. Research in active male populations, though once relatively sparse, is increasing [103,105,121,127,[130][131][132][133][134][135][136][137][138]. ...
... One such possible indicator is RMR ratio , calculated as the quotient of an individual's measured RMR versus that predicted using an equation based on contributing variables such as age, height, body mass, and FFM [5]. Numerous investigations (but not all [107,[115][116][117][118]) have observed relationships between RMR ratio and associated markers of EA in active individuals, including 7-day EA [119]; within-day EB [120,121]; menstrual/estrogen status [119,120,[122][123][124][125][126]; volumetric bone characteristics [127] and formation markers [122]; alterations in TT 3 concentrations [122,124,125,128,129]; and in other hormones such as ghrelin, leptin, peptide YY, and insulin-like growth factor-1 [123,125,129,130]. Research in active male populations, though once relatively sparse, is increasing [103,105,121,127,[130][131][132][133][134][135][136][137][138]. ...
... Longitudinal studies assessing the impact of increased EB over time in metabolically suppressed individuals may help elucidate the time course of RMR recovery in relation to other physiological signs such as restoration of menses and hormone concentrations. Research on the effect of within-day changes in EA/EB [120,121,135,176,178] and resulting metabolic disturbances should also be further pursued. ...
Full-text available
Resting metabolic rate (RMR) is a significant contributor to an individual’s total energy expenditure. As such, RMR plays an important role in body weight regulation across populations ranging from inactive individuals to athletes. In addition, RMR may also be used to screen for low energy availability and energy deficiency in athletes, and thus may be useful in identifying individuals at risk for the deleterious consequences of chronic energy deficiency. Given its importance in both clinical and research settings within the fields of exercise physiology, dietetics, and sports medicine, the valid assessment of RMR is critical. However, factors including varying states of energy balance (both short- and long-term energy deficit or surplus), energy availability, and prior food intake or exercise may influence resulting RMR measures, potentially introducing error into observed values. The purpose of this review is to summarize the relationships between short- and long-term changes in energetic status and resulting RMR measures, consider these findings in the context of relevant recommendations for RMR assessment, and provide suggestions for future research.
... The risks of IF may outweigh the benefits in the athlete population, because a limited timeframe for eating may increase risk of developing low energy availability and lead to related consequences to health and performance [116][117][118]. It is already difficult for most athletes to meet the required caloric intake for muscle preservation and training performance, and it becomes much more difficult when one's eating window is reduced. ...
... This increases fatty oxidation and promotes ketosis, similar to the ketogenic diet. Thus, IF may be useful for weight loss and athletes who must maintain a strict weight class; however, it may lead to decrements in other aspects of performance, as seen in within-day energy deficits associated with metabolic compensation in elite collegiate swimmers and male endurance athletes, and menstrual dysfunction in female endurance athletes [116][117][118]. The varying results seen in the athlete population suggests more studies need to be conducted to elucidate the effect of intermittent fasting on performance. ...
Full-text available
Background: Nutrition fuels optimal performance for athletes. With increased research developments, numerous diets available, and publicity from professional athletes, a review of dietary patterns impact on athletic performance is warranted. Results: The Mediterranean diet is a low inflammatory diet linked to improved power and muscle endurance and body composition. Ketogenic diets are restrictive of carbohydrates and proteins. Though both show no decrements in weight loss, ketogenic diets, which is a more restrictive form of low-carbohydrate diets, can be more difficult to follow. High-protein and protein-paced versions of low-carbohydrate diets have also shown to benefit athletic performance. Plant-based diets have many variations. Vegans are at risk of micronutrient deficiencies and decreased leucine content, and therefore, decreased muscle protein synthesis. However, the literature has not shown decreases in performance compared to omnivores. Intermittent fasting has many different versions, which may not suit those with comorbidities or specific needs as well as lead to decreases in sprint speed and worsening time to exhaustion. Conclusions: This paper critically evaluates the research on diets in relation to athletic performance and details some of the potential risks that should be monitored. No one diet is universally recommend for athletes; however, this article provides the information for athletes to analyze, in conjunction with medical professional counsel, their own diet and consider sustainable changes that can help achieve performance and body habitus goals.
... This contributed to the popularity of becoming "fat-adapted" among ultramarathon runners, an approach to nutrition and training which aims to improve the body's ability to oxidise fat, sparing muscle glycogen and delaying fatigue. However, subsequent research has shown that within-day energy deficits, such as those involved in fasted training, are associated with clinical markers of metabolic and menstrual disturbances in female endurance athletes [21]. ...
... Moreover, female ultramarathon runners have an elevated risk of eating disorders and the athlete triad [51]. While low energy availability negatively affects all athletes, the consequences for females are more rapid, and even withinday deficits affect menstrual function and bone turnover [21,85]. Interestingly, in the study by Høeg et al., male ultramarathon athletes were in fact more likely to have low bone mineral density than females, and further research is required to confirm this finding [51]. ...
Full-text available
Background There is evidence of sex differences in the physiology of endurance exercise, yet most of the advice and guidelines on training, racing, nutrition, and recovery for ultramarathons are based on research that has largely excluded female athletes. The objective was therefore to review the current knowledge of sex differences in ultramarathon runners and determine if sufficient evidence exists for providing separate guidelines for males and females. Methods This systematic review was carried out in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Three databases were searched for studies investigating differences in elite and recreational male and female ultramarathon runners. Studies were included if they compared males and females and looked at outcomes relating to the performance or health of ultramarathon runners. The quality of the included studies was determined using the Grading of Recommendations Assessment Development and Evaluation (GRADE) approach. Results The search strategy identified 45 studies that met the inclusion criteria. Most studies were observational in design, with only three papers based on randomised controlled trials. The overall quality of the evidence was low. Sex differences in the predictors of ultramarathon performance; physiological responses to training, racing, and recovery; chronic and acute health issues; and pacing strategies were found. There were areas with contradictory findings, and very few studies examined specific interventions. Conclusion The results from this review suggest that the development of sex-specific guidelines for ultramarathon coaches and athletes could have a significant effect on the performance and health of female runners. At present, there is insufficient high-quality evidence on which to formulate these guidelines, and further research is required.
... Further, these estimations were done only for a single day, thus, not capturing a cumulative energy availability, including the variation in energy intake and activities across a weekly schedule. However, even a withinday energy deficiency has been reported to be associated with reduced RMR, lower estrogen and increased cortisol levels [1,60]. Apart from this, the players were monitored during their training camp, which might be different from their regular training and dietary habits. ...
Full-text available
PurposeEnergy availability (EA) is considered an important measure for athletes, particularly due to the possible health and performance outcomes defined under the RED-S. Low EA is reported to have far-reaching health consequences among female athletes, especially in weight-sensitive sport. However, it is less explored among male athletes, particularly in the traditional Indian tag sport called Kho-Kho. This cross-sectional observational study aimed to determine the prevalence of LEA and associated RED-S health and performance outcomes among Kho-Kho players.Methods Fifty-two male national-level Kho-Kho players aged 16–31 years were assessed for energy availability, bone mineral density (BMD), sleep quality, disordered eating, selected metabolic (hemoglobin, blood glucose, etc.) and performance outcomes (agility, speed, and power) as per RED-S risk assessment tool. Differences across the low EA (≤ 25 kcal/ kg fat-free mass) and Optimal EA (> 25 kcal/ kg fat-free mass) groups were evaluated using the Independent Samples t test and the chi-square test.ResultsLow EA among athletes was associated with lower z-scores for BMD, sleep quality and agility, compared to athletes with optimal EA. At least one moderate-to-high RED-S risk outcome was prevalent among 98% of the Kho-Kho players, irrespective of EA. Most athletes exhibited a lower EAT score and disordered eating outcomes, with no significant differences across groups.Conclusion The male Kho-Kho players showed a prevalence of low EA that can be due to higher training loads and unintentional under-eating, not related to an eating disorder. The players also exhibited higher RED-S risk outcomes; however, it was irrespective of low EA.
... Enfeksiyon, hastalık, yorgunluk ve besin eksiklikleri ile kas-iskelet sistemi, endokrin, gastrointestinal, renal, psikolojik, kardiyovasküler ve performans eksiklikleri gibi birçok rahatsızlığa neden olur. Sporcular, büyük enerji açıkları uzun süre korunduğunda kadınlarda hormon seviyelerinde değişiklik, olumsuz vücut kompozisyonu, katabolik belirtiler ve menstüral işlev bozukluğu ile karşılaşırlar (Fahrenholtz, Sjödin, Benardot, Tornberg, Skouby, Faber, Sundgot-Borgen & Melin, 2018;Riviere, Leach, Mann, Robinson, Burnett, Babu, & Frugé, 2021;Torstveit ve ark., 2008) . ...
Beslenme sağlık ve gelişim için çok önemli bir konudur. Yeme davranışı ise genç bir bireyin fiziksel gelişimi, sağlığı ve kimliği için temel oluşturur ve bilgi, tutumlar, sosyodemografik özellikler ve davranışsal, ailesel ve yaşam tarzı faktörleri dahil olmak üzere çok çeşitli faktörler tarafından şekillenir. Dengeli ve iyi beslenme ile atletik performans arasında doğru orantılı ilişki iyi bilinmektedir Bu durum spor alanında eğitim gören öğrenciler için daha da önem taşımaktadır. Bu çalışma spor bilimleri fakültesi öğrencilerinin sağlıklı beslenme ile ilgili tutumlarını yaptıkları spor branşına (takım ya da bireysel) göre değerlendirmek amacıyla yapılmıştır. Çalışma Muğla Sıtkı Koçman Üniversitesi Spor Bilimleri Fakültesi’nde öğrenim gören öğrenciler üzerinde gerçekleştirilmiştir. Katılımcıların sağlıklı beslenme tutumlarının belirlenmesi için demografik bilgilerin ve spor branşının sorgulandığı kişisel bilgi formunun yanı sıra Sağlıklı Beslenmeye İlişkin Tutum Ölçeği (SBİTÖ) uygulanmıştır. Araştırmaya, 206 kadın ve 348 erkek olmak üzere toplamda 554 Spor Bilimleri Fakültesi öğrencisi gönüllü olarak katılmıştır. Verilerin normal dağılıma uygun olup olmadıkları Kolmogorov Smirnov testi ile test edilmiştir. Gruplar arası karşılaştırmada Independent-Samples T testi, çoklu karşılaştırmalarda One Way Anova ve karşılaştırma sonucu farklılığı meydana getiren grubu tespit etmek amacıyla da Tukey HSD testleri kullanılmıştır. Araştırmaya katılan kadın öğrencilerin SBİTÖ değerleri 73,11  12,77 olarak bulunurken, erkek öğrencilerin SBİTÖ değerleri 75,60  12,27 olarak tespit edilmiştir (p0,05). Araştırmada elde edilen bulgulara göre, Spor Bilimleri Fakültesi öğrencilerinin sağlıklı beslenmeye ilişkin tutumları, tüm alt boyutlarda takım sporu ya da bireysel spor yapmalarına göre farklılaşmaktadır (p0.05). Sonuç olarak, üniversiteli erkek sporcuların kadın sporculara göre, bireysel sporcuların da takım sporu ile uğraşan öğrencilere göre sağlıklı beslenmeye ilişkin tutum açısından daha iyi durumda olduğu söylenebilir.
... In this study we did not directly assess energy availability, which requires assessments of body composition, energy intake, and exercise energy expenditure. Although it is well-recognized that LEA is the etiological factor underpinning the syndrome of RED-S (Mountjoy et al., 2014), several barriers prohibit the direct measurement of energy availability from being a practical and reliable option (Heikura et al., 2017;Burke et al., 2018;Fahrenholtz et al., 2018;Mountjoy et al., 2018). Questionnaires can therefore be a convenient method for screening, with the LEAF-Q (Melin et al., 2014) and the EDE-Q (Fairburn and Beglin, 1994) being the most widely used and validated questionnaires in the research of RED-S (Sim and Burns, 2021). ...
Full-text available
Relative energy deficiency in sport (RED-S) is a complex syndrome describing health and performance consequences of low energy availability (LEA) and is common among female endurance athletes. Various underlying causes of LEA have been reported, including disordered eating behavior (DE), but studies investigating the association with exercise addiction and food intolerances are lacking. Therefore, the aim of this cross-sectional study was to investigate the association between DE, exercise addiction and food intolerances in athletes at risk of LEA compared to those with low risk. Female endurance athletes, 18-35 years, training ≥5 times/week were recruited in Norway, Sweden, Ireland, and Germany. Participants completed an online-survey comprising the LEA in Females Questionnaire (LEAF-Q), Exercise Addiction Inventory (EAI), Eating Disorder Examination Questionnaire (EDE-Q), and questions regarding food intolerances. Of the 202 participants who met the inclusion criteria and completed the online survey, 65% were at risk of LEA, 23% were at risk of exercise addiction, and 21% had DE. Athletes at risk of LEA had higher EDE-Q and EAI scores compared to athletes with low risk. EAI score remained higher in athletes with risk of LEA after excluding athletes with DE. Athletes at risk of LEA did not report more food intolerances (17 vs. 10%, P = 0.198), but were more frequently reported by athletes with DE (28 vs. 11%, P = 0.004). In conclusion, these athletes had a high risk of LEA, exercise addiction, and DE. Exercise addiction should be considered as an additional risk factor in the prevention, early detection, and targeted treatment of REDS among female endurance athletes.
... However, adding to our worries on EA is the finding that almost half of the athletes practiced skipping meals during weight-loss periods. Previous studies have found that adjusting EA proportionally within a day is necessary to avoid negative health effects in both males and females [42,43]. Supporting the suggestion of high frequency of LEA in this sample is the symptom frequency of LEA measured by the LEAF-q (i.e., 56% with symptoms). ...
Full-text available
Background: To explore motives for combat sport participation, weight regulation practices, symptoms of low energy availability (LEA), disordered eating (DE) or eating disorders (ED), and any experiences with sexual harassment (SH) among female combat-sport athletes. Methods: In total, 29 athletes were recruited by social media and in clubs. Participants responded to a questionnaire on health behavior and mental health and completed diet registration and a DXA-scan. Results: Most athletes started combat sports to feel empowered and experienced an inclusive milieu, but the frequency of health issues was high. A total of 21-67% had symptoms of ED, suffered from injuries, had low site-specific BMD, and/or symptoms of LEA. Athletes had insufficient intake of energy and nutrients, and <50% received any dietary information or guidance from their clubs. Most athletes complied with favorable weight-loss strategies; still, >20% used unfavorable methods and rapid weight-loss periods. A total of 70% of the athletes had experienced SH, of which 41% experienced SH within the combat-sport context. Conclusion: Combat sport offers an inclusive milieu, which may increase women's health and confidence; still, our results indicates a need for actions to safeguard female combat-sport athletes' mental and physical health, implying a cultural change within the community of combat sport and a need for increased health and nutrition literacy.
Full-text available
Triathlon is a physically demanding sport, requiring athletes to make informed decisions regarding their daily food and fluid intake to align with daily training. With an increase in uptake for online learning, remotely delivered education programs offer an opportunity to improve nutritional knowledge and subsequent dietary intake in athletes. This single-arm observational study aimed to evaluate the effectiveness of a remotely delivered nutrition education program on sports nutrition knowledge and the dietary intake of junior elite triathletes (n = 21; female n = 9; male n = 12; 18.9 ± 1.6 y). A total of 18 participants completed dietary intake assessments (4-day food diary via Easy Diet DiaryTM) and 14 participants completed an 83-question sports nutrition knowledge assessment (Sports Nutrition Knowledge Questionnaire (SNKQ)) before and after the 8-week program. Sports nutrition knowledge scores improved by 15% (p < 0.001, ES = 0.9) following the program. Male participants reported higher energy intakes before (3348 kJ, 95% CI: 117–6579; p = 0.043) and after (3644 kJ, 95% CI: 451–6836; p = 0.028) the program compared to females. Carbohydrate intake at breakfast (p = 0.022), daily intakes of fruit (p = 0.033), dairy (p = 0.01) and calcium (p = 0.029) increased following nutrition education. Irrespective of gender, participants had higher intakes of energy (p < 0.001), carbohydrate (p = 0.001), protein (p = 0.007), and fat (p = 0.007) on heavy training days compared to lighter training days before and after the program with total nutrition knowledge scores negatively correlated with discretionary food intake (r = −0.695, p = 0.001). A remotely delivered nutrition education program by an accredited sports nutrition professional improved sports nutrition knowledge and subsequent dietary intake of junior elite triathletes, suggesting remote delivery of nutrition education may prove effective when social distancing requirements prevent face-to-face opportunities.
To determine whether mismatched energy intake and expenditure across the day and associated sex differences may be related with metabolic compensation and/or negative health outcomes, we assessed total-day and hourly energy balance (TDEB and EB), total-day and hourly energy intake (TDEI and EI), total-day and hourly energy expenditure (TDEE and EE) and within-day energy balance (WDEB) in elite male and female swimmers (n=25; 18-22yr). Total triiodothyronine (TT3), resting metabolic rate (RMR), and the ratio of actual-to-predicted RMR were determined. Males exhibited higher TDEB (+758 ± 702 kcal vs +52 ± 505 kcal, t-test; p=0.007) than females. Males exhibited a more positive hourly EB, driven by greater hourly EI at hours 1100, 1300, 1600, and 1900hr (ANOVA, p<0.05), while EE did not differ. TT3 was negatively correlated with consecutive hours of negative EB (R=-0.604, p=0.049) and positively correlated to hours in EB (R=0.740, p=0.009) in those exhibiting metabolic suppression (n=12). In individuals in TDEB (n=21), “backloaders” (consumption of ≥ 50% daily kcals at or after 1700 hrs) had lower TT3 (79.3 ng/dL vs 92.9 ng/dL, p=0.009) than “non-backloaders” (n=12). WDEB analyses indicate a greater risk of energy deficiency in females and may capture indices of metabolic compensation not evident with EB analyses alone.
Full-text available
It is the position of the Academy of Nutrition and Dietetics (Academy), Dietitians of Canada (DC), and the American College of Sports Medicine (ACSM) that the performance of, and recovery from, sporting activities are enhanced by well-chosen nutrition strategies. These organizations provide guidelines for the appropriate type, amount, and timing of intake of food, fluids, and supplements to promote optimal health and performance across different scenarios of training and competitive sport. This position paper was prepared for members of the Academy, DC, and ACSM, other professional associations, government agencies, industry, and the public. It outlines the Academy’s, DC’s, and ACSM’s stance on nutrition factors that have been determined to influence athletic performance and emerging trends in the field of sports nutrition. Athletes should be referred to a registered dietitian nutritionist for a personalized nutrition plan. In the United States and in Canada, the Certified Specialist in Sports Dietetics is a registered dietitian nutritionist and a credentialed sports nutrition expert.
Full-text available
Low or reduced energy availability (LEA) is linked to functional hypothalamic oligomenorrhea/amenorrhea (FHA), which is frequently reported in weight-sensitive sports. This makes LEA a major nutritional concern for female athletes. The aim of this study was to describe dietary characteristics of athletes with LEA and/or FHA. Endurance athletes (n = 45) were recruited from national teams and competitive clubs. Protocols included gynecological examination, body composition, eating disorder evaluation, and 7-day dietary intake and EA assessment. Athletes with disordered eating behavior/eating disorders (n = 11), menstrual dysfunction other than FHA (n = 5), and low dietary record validity (n = 4) were excluded. Remaining subjects (n = 25) were characterized by EA [optimal: ≥ 45 kcal (188 kJ)/kg fat-free mass (FFM)/day (n = 11), LEA: < 45 kcal (188 kJ)/kg FFM/day (n = 14)] and reproductive function [eumenorrhea (EUM; n = 10), FHA (n = 15)]. There was no difference in EA between FHA and EUM subjects. However, FHA and LEA subjects shared the same dietary characteristics of lower energy density (ED) [(P = 0.012; P = 0.020), respectively], and fat content [(P = 0.047; P = 0.027), respectively]. Furthermore, FHA subjects had a lower intake of carbohydrate-rich foods (P = 0.019), higher fiber content (P < 0.001), and drive for thinness score (P = 0.003). Conclusively, low ED together with high fiber content may constitute targets for dietary intervention in order to prevent and treat LEA and FHA in female athletes.
Full-text available
The female athlete triad (Triad), links low energy availability (EA), with menstrual dysfunction (MD), and impaired bone health. The aims of this study were to examine associations between EA/MD and energy metabolism and the prevalence of Triad-associated conditions in endurance athletes. Forty women [26.2 ± 5.5 years, body mass index (BMI) 20.6 ± 2.0 kg/m(2) , body fat 20.0 ± 3.0%], exercising 11.4 ± 4.5 h/week, were recruited from national teams and competitive clubs. Protocol included gynecological examination; assessment of bone health; indirect respiratory calorimetry; diet and exercise measured 7 days to assess EA; eating disorder (ED) examination; blood analysis. Subjects with low/reduced EA (< 45 kcal/kg FFM/day), had lower resting metabolic rate (RMR) compared with those with optimal EA [28.4 ± 2.0 kcal/kg fat-free mass (FFM)/day vs 30.5 ± 2.2 kcal/kg FFM/day, P < 0.01], as did subjects with MD compared with eumenorrheic subjects (28.6 ± 2.4 kcal/kg FFM/day vs 30.2 ± 1.8 kcal/kg FFM/day, P < 0.05). 63% had low/reduced EA, 25% ED, 60% MD, 45% impaired bone health, and 23% had all three Triad conditions. 53% had low RMR, 25% hypercholesterolemia, and 38% hypoglycemia. Conclusively, athletes with low/reduced EA and/or MD had lowered RMR. Triad-associated conditions were common in this group of athletes, despite a normal BMI range. The high prevalence of ED, MD, and impaired bone health emphasizes the importance of prevention, early detection, and treatment of energy deficiency.
Full-text available
Protecting the health of the athlete is a goal of the International Olympic Committee (IOC). The IOC convened an expert panel to update the 2005 IOC Consensus Statement on the Female Athlete Triad. This Consensus Statement replaces the previous and provides guidelines to guide risk assessment, treatment and return-to-play decisions. The IOC expert working group introduces a broader, more comprehensive term for the condition previously known as 'Female Athlete Triad'. The term 'Relative Energy Deficiency in Sport' (RED-S), points to the complexity involved and the fact that male athletes are also affected. The syndrome of RED-S refers to impaired physiological function including, but not limited to, metabolic rate, menstrual function, bone health, immunity, protein synthesis, cardiovascular health caused by relative energy deficiency. The cause of this syndrome is energy deficiency relative to the balance between dietary energy intake and energy expenditure required for health and activities of daily living, growth and sporting activities. Psychological consequences can either precede RED-S or be the result of RED-S. The clinical phenomenon is not a 'triad' of the three entities of energy availability, menstrual function and bone health, but rather a syndrome that affects many aspects of physiological function, health and athletic performance. This Consensus Statement also recommends practical clinical models for the management of affected athletes. The 'Sport Risk Assessment and Return to Play Model' categorises the syndrome into three groups and translates these classifications into clinical recommendations.
Full-text available
Low energy availability (EA) in female athletes with or without an eating disorder (ED) increases the risk of oligomenorrhoea/functional hypothalamic amenorrhoea and impaired bone health, a syndrome called the female athlete triad (Triad). There are validated psychometric instruments developed to detect disordered eating behaviour (DE), but no validated screening tool to detect persistent low EA and Triad conditions, with or without DE/ED, is available. The aim of this observational study was to develop and test a screening tool designed to identify female athletes at risk for the Triad. Female athletes (n=84) with 18-39 years of age and training ≥5 times/week filled out the Low Energy Availability in Females Questionnaire (LEAF-Q), which comprised questions regarding injuries and gastrointestinal and reproductive function. Reliability and internal consistency were evaluated in a subsample of female dancers and endurance athletes (n=37). Discriminant as well as concurrent validity was evaluated by testing self-reported data against measured current EA, menstrual function and bone health in endurance athletes from sports such as long distance running and triathlon (n=45). The 25-item LEAF-Q produced an acceptable sensitivity (78%) and specificity (90%) in order to correctly classify current EA and/or reproductive function and/or bone health. The LEAF-Q is brief and easy to administer, and relevant as a complement to existing validated DE screening instruments, when screening female athletes at risk for the Triad, in order to enable early detection and intervention.
Full-text available
Benardot, D. (2013). Energy Thermodynamics Revisited: Energy Intake Strategies for Optimizing Athlete Body Composition and Performance. PENSAR EN MOVIMIENTO: Revista de Ciencias del Ejercicio y la Salud, 11 (2), 1-13. A key feature of physical activity is that it results in an increased rate of energy expenditure and, as a result of metabolic inefficiencies that lead to high heat production, an increase in the requirement to dissipate the added heat through sweat. Nevertheless, studies assessing food and fluid intakes of athletes commonly find that they fail to optimally satisfy their daily predicted requirements of both energy and fluid, causing them to perform at levels below their conditioned capacities. To some extent, this problem results from an excess reliance on the sensations of ‘hunger’ and ‘thirst’ to guide energy and fluid intakes. However, there are also common misunderstandings of the best nutrition strategies for achieving optimal body composition and performance. Athletes in all sports should strive to improve the strength-to-weight ratio to enable an enhanced ability to overcome sport-related resistance, but this may be misinterpreted as a need to achieve a lower weight, which may result in an under-consumption of energy through restrained eating and special ‘diets’. The outcome, however, is nearly always the precise opposite of the desired effect, with lower strength-to-weight ratios that result in an ever-increasing downward spiral in energy consumption. This paper focuses on within-day energy balance eating and drinking strategies that are now successfully followed by many elite-level athletes, including longdistance runners, sprinters, gymnasts, figure skaters, and football players. These strategies can help athletes avoid the common errors of under-consumption while simultaneously improving both body composition and performance.
Full-text available
Unlabelled: It is hypothesized that exercise-related menstrual dysfunction (ExMD) results from low energy availability (EA), defined as energy intake (EI)--exercise energy expenditure (EEE). When EI is too low, resting metabolic rate (RMR) may be reduced to conserve energy. Purpose: To measure changes in RMR and EA, using four methods to quantify EEE, before/after a 6-month diet intervention aimed at restoring menses in women with ExMD; eumenorrheic (Eumen) active controls (n = 9) were also measured. Methods: Active women with ExMD (n = 8) consumed +360 kcal/d (supplement) for 6 months; RMR was measured 2 times at 0 months/6 months. EI and total energy expenditure (TEE) were estimated using 7-day diet/activity records, with EA assessed using four methods to quantify EEE. Results: At baseline, groups did not differ for age, gynecological age, body weight, lean/fat mass, VO₂max, EI and EA, but mean TEE was higher in ExMD (58.3 ± 4.4 kcal/ kgFFM/d; Eumen = 50.6 ± 2.4; p < .001) and energy balance (EB) more negative (-10.3 ± 6.9 kcal/kgFFM/d; Eumen=-3.0 ± 9.7; p = .049). RMR was higher in ExMD (31.3 ± 1.8 kcal/kgFFM/d) vs. Eumen (29.1 ± 1.9; p < .02). The intervention increased weight (1.6 ± 2.0 kg; p = .029), but there were no significant changes in EA (0-month range = 28.2-36.7 kcal/kgFFM/d; 6-month range = 30.0-45.4; p > .05), EB (6 months = -0.7 ± 15.1 kcal/kgFFM/d) or RMR (0 months = 1515 ± 142; 6 months = 1522 ± 134 kcal/d). Assessment of EA varied dramatically (~30%) by method used. Conclusions: For the ExMD group, EI and weight increased with +360 kcal/d for 6 months, but there were no significant changes in EB, EA or RMR. No threshold EA value was associated with ExMD. Future research should include TEE, EB and clearly quantifying EEE (e.g.,>4 MET) if EA is measured.
To determine the effect of dietary energy restriction on gonadotropins, we assayed LH and FSH in samples drawn at 10- and 60-min intervals, respectively, over 24 h from seven young women (mean +/- SE gynecological age, 7.7 +/- 1.2 yr) on day 9, 10, or 11 of two menstrual cycles. Cortisol was measured in samples collected at 30-min intervals. During the 4 previous days and the day of sampling, dietary energy intake was set at either 45 or 10 Cal/kg lean body in random order. Beginning 2 days before treatment, blood was sampled daily at 0800 h and assayed for T3, insulin-like growth factor-I, and insulin. Estradiol was measured in samples collected daily and at 6-h intervals on the day of frequent sampling. By the day of frequent sampling, dietary restriction had reduced T3 20% (P < 0.01), insulin-like growth factor-I 58% (P < 0.001), and insulin 54% (P < 0.001). Twenty-four-hour transverse means for LH (P = 0.3), FSH (P = 0.2), estradiol (P = 0.3), and cortisol (P = 0.13) were unaffected, but LH pulse frequency was reduced 23% (P < 0.01), especially during waking hours, whereas LH pulse amplitude was increased 40% (P = 0.05), especially during sleep. These results support the hypothesis that LH pulsatility depends upon energy availability in women, as it does in other mammalian species.
Competitive female athletes restrict energy intake and increase exercise energy expenditure frequently resulting in ovarian suppression. The purpose of this study was to determine the impact of ovarian suppression and energy deficit on swimming performance (400m swim velocity). Menstrual status was determined by circulating estradiol (E2) and progesterone (P4) in ten junior elite female swimmers (15-17 yrs). The athletes were categorized as cyclic (CYC) or ovarian suppressed (OVS). They were evaluated every two weeks for metabolic hormones, bioenergetic parameters and sport performance over the 12-week season. CYC and OVS athletes were similar (p > 0.05) in age (CYC = 16.2 ± 1.8 yr; OVS = 17 ± 1.7 yr), BMI (CYC = 21 ± 0.4 kg/m; OVS = 25 ± 0.8 kg/m), and gynecological age (CYC = 2.6 ± 1.1 yr; OVS = 2.8 ± 1.5 yr). OVS had suppressed P4 (p < 0.001) and E2 (p = 0.002) across the season. Total triiodothyronine (TT3) and insulin-like growth factor (IGF-1) were lower in OVS (TT3: CYC = 1.6 ± 0.2 nmol/l; OVS = 1.4 ± 0.1 nmol/l p < 0.001; IGF-1: CYC = 243 ± 1 μg/ml; OVS = 214 ± 3 μg/ml p < 0.001) than CYC at Week 12. Energy intake (p < 0.001) and energy availability (p < 0.001) were significantly lower in OVS versus CYC. OVS exhibited a 9.8% decline in [INCREMENT]400m-swim velocity compared to an 8.2% improvement in CYC at Week 12. Ovarian steroids (P4 and E2), metabolic hormones (TT3 and IGF-1) and energy status markers (EA and EI) were highly correlated with sport performance. This study illustrates that when exercise training occurs in the presence of ovarian suppression with evidence for energy conservation (ie. reduced TT3), it is associated with poor sport performance. These data from junior elite female athletes support the need for dietary periodization to help optimize energy intake for appropriate training adaptation and maximal sport performance.