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This review updates and complements the review of energy balance and body composition in the Proceedings of the 2003 IOC Consensus Conference on Sports Nutrition. It argues that the concept of energy availability is more useful than the concept of energy balance for managing the diets of athletes. It then summarizes recent reports of the existence, aetiologies, and clinical consequences of low energy availability in athletes. This is followed by a review of recent research on the failure of appetite to increase ad libitum energy intake in compensation for exercise energy expenditure. The review closes by summarizing the implications of this research for managing the diets of athletes.
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Journal of Sports Sciences
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Energy availability in athletes
Anne B. Loucks a , Bente Kiens b & Hattie H. Wright c
a Department of Biological Sciences, Ohio University, Athens, Ohio, USA
b The Molecular Physiology Group, Department of Exercise and Sport Sciences, University of
Copenhagen, Copenhagen, Denmark
c Center of Excellence for Nutrition, Faculty of Health Sciences, North-West University,
Potchefstroom, South Africa
Available online: 28 Jul 2011
To cite this article: Anne B. Loucks, Bente Kiens & Hattie H. Wright (2011): Energy availability in athletes, Journal of Sports
Sciences, 29:sup1, S7-S15
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Energy availability in athletes
Department of Biological Sciences, Ohio University, Athens, Ohio, USA,
The Molecular Physiology Group, Department of
Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark, and
Center of Excellence for Nutrition,
Faculty of Health Sciences, North-West University, Potchefstroom, South Africa
(Accepted 13 May 2011)
This review updates and complements the review of energy balance and body composition in the Proceedings of the 2003
IOC Consensus Conference on Sports Nutrition. It argues that the concept of energy availability is more useful than the
concept of energy balance for managing the diets of athletes. It then summarizes recent reports of the existence, aetiologies,
and clinical consequences of low energy availability in athletes. This is followed by a review of recent research on the failure
of appetite to increase ad libitum energy intake in compensation for exercise energy expenditure. The review closes by
summarizing the implications of this research for managing the diets of athletes.
Keywords: Energy availability, energy balance, diet, exercise, appetite
In the 2003 IOC Consensus Conference on Sports
Nutrition, evidence was presented that many ath-
letes, most often female athletes, were deficient in
energy, and especially energy in the form of
carbohydrates, resulting in impaired health and
performance (Loucks, 2004). It was emphasized,
however, that energy balance is not the objective of
athletic training whenever athletes seek to modify
their body size and composition to achieve perfor-
mance objectives. They then need to carefully
manage their diet and exercise regimens to avoid
compromising their health.
Distinctions between energy availability and
energy balance
In the field of bioenergetics, the concept of energy
availability recognizes that dietary energy is expended
in several fundamental physiological processes, in-
cluding cellular maintenance, thermoregulation,
growth, reproduction, immunity, and locomotion
(Wade & Jones, 2004). Energy expended in one of
these processes is not available for others. Therefore,
bioenergeticists investigate the effects of a particular
metabolic demand on physiological systems in terms
of energy availability. They define energy availability
as dietary energy intake minus the energy expended
in the particular metabolic demand of interest. In
experiments investigating effects of cold exposure, for
example, energy availability would be defined,
quantified, and controlled as dietary energy intake
minus the energy cost of thermogenesis.
Exercise training increases, and in endurance
sports may double or even quadruple, the amount
of energy expended in locomotion. In exercise
physiology, therefore, energy availability is defined
as dietary energy intake minus the energy expended
in exercise (EA ¼EI – EEE). As the amount of dietary
energy remaining after exercise training for all other
metabolic processes, energy availability is an input to
the body’s physiological systems.
In the field of dietetics, the concept of energy
balance has been the usual basis of research and
practice. Defined as dietary energy intake minus total
energy expenditure (EB ¼EI – TEE), energy balance
is the amount of dietary energy added to or lost from
the body’s energy stores after the body’s physiological
systems have done all their work for the day. Thus
energy balance is an output from those systems. For
healthy young adults, EB ¼0 kcal day
EA ¼45 kcal kg FFM
(where FFM ¼
fat-free mass).
Correspondence: A. B. Loucks, Department of Biological Sciences, Ohio University, Athens, OH 45701, USA. E-mail:
Journal of Sports Sciences, 2011; 29(S1): S7–S15
ISSN 0264-0414 print/ISSN 1466-447X online Ó2011 Taylor & Francis
Downloaded by [ ] at 22:56 17 January 2012
The contrast between energy availability and
energy balance is illustrated in Figure 1, which shows
data collected while eight lean, untrained men lived in
a room calorimeter for a week (Stubbs et al., 2004).
During that week, their energy intake (2770 kcal
), exercise energy expenditure (840 kcal
), and energy availability (2770 840 ¼1930
kcal day
30 kcal kg FFM
constant. Meanwhile, the magnitude of their negative
energy balance (2770 – 4500 ¼–1730 kcal day
Day 1) decreased towards zero at a rate of *90
kcal day
as various physiological processes slo-
wed down. At this rate, they would have recovered
EB ¼0 kcal day
(a pathological state of energy
balance achieved by suppressing physiological sys-
tems) in 3 weeks, while remaining in severely low
energy availability.
Undergraduate nutrition textbooks assert that
energy requirements can be determined by measur-
ing energy expenditure, but measures of energy
expenditure contain no information about whether
physiological systems are functioning in a healthy
manner. Because physiological processes are sup-
pressed by severely low energy availability, measure-
ments of total or resting energy expenditure will
underestimate a chronically undernourished athlete’s
energy requirements.
Therefore, because energy balance is an output
from, rather than an input to, physiological systems,
because it does not contain reliable information
about energy requirements, and because it is not
even the objective of athletic training, energy balance
is not a useful concept for managing an athlete’s
Figure 1. Negative energy balance rising at a rate of 90
kcal day
as metabolic processes were suppressed while the
energy intake (2770 kcal day
), exercise energy expenditure
(840 kcal day
), and energy availability (2770 840 ¼1930
kcal day
) of eight lean, untrained men remained constant. EI
(þ)¼energy intake, TEE (¤)¼total energy expenditure, EEE
()¼exercise energy expenditure, EA (.)¼energy availability, EB
(&)¼energy balance. Original figure based on data in Stubbs
et al. (2004).
Energy deficiency in athletes: Existence,
aetiologies, and consequences
At the 2003 IOC Consensus Conference, the
existence of widespread energy deficiency in athletes
was still questioned. Since then, the IOC Medical
Commission has published two position stands
(Sangenis et al., 2005, 2006) and the American
College of Sports Medicine (ACSM) has published a
revised position stand (Nattiv, Loucks, Manore,
Sundgot-Borgen, & Warren, 2007) on the ‘‘female
athlete triad’’. In addition, a coaches’ handbook on
Managing the Female Athlete Triad developed by
the co-chairs of the athlete interest group of the
Academy of Eating Disorders has been published by
the US National Collegiate Athletics Association
(NCAA) (Sherman & Thompson, 2005). All four
publications attribute the functional hypothalamic
menstrual disorders and low bone mineral density
found in many female athletes to energy deficiency,
but the ACSM position stand differs from the other
three in that it excludes disordered eating and eating
disorders as necessary components of the triad. The
ACSM emphasizes that athletes who expend large
amounts of energy in prolonged exercise training can
become energy deficient without eating disorders,
disordered eating or even dietary restriction.
The ACSM identified three distinct origins of
energy deficiency in athletes. The first is obsessive
eating disorders with their attendant clinical mental
illnesses. The second is intentional and rational but
mismanaged efforts to reduce body size and fatness
to qualify for and succeed in athletic competitions.
This mismanagement may or may not include
disordered eating behaviours such as fasting, diet
pills, laxatives, diuretics, enemas, and vomiting that
are entrenched parts of the culture and lore of some
sports. The third is the inadvertent failure to increase
energy intake to compensate for the energy expended
in exercise. The percentages of cases of the female
athlete triad originating from these three sources are
unknown, but ACSM emphasized that any epide-
miological study requiring the presence of an eating
disorder or disordered eating for diagnosing cases of
the triad (e.g. Schtscherbyna, Soares, de Oliveira, &
Ribeiro, 2009) will underestimate its prevalence.
Sports vary greatly in the relative importance of
various factors for competitive success. As they strive
to achieve sport-specific mixes of these factors,
athletes engage in different diet and exercise beha-
viours that impact energy availability. In endurance
sports, prolonged exercise training greatly reduces
energy availability, unless energy intake is increased
to replace the energy expended in exercise. In sports
where less energy is expended in training, dietary
restriction may be a prominent part of the strategy
for reducing energy availability to modify body size
and composition.
S8 A. B. Loucks et al.
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Female athletes may also under-eat for reasons
unrelated to sport. Around the world about twice as
many young women as men at every decile of body
mass index perceive themselves to be overweight
(Wardle, Haase, & Steptoe, 2006). The dispropor-
tionate numbers actively trying to lose weight are
even higher, and this disproportion increases as body
mass index declines, so that almost nine times as
many lean women as lean men are actively trying to
lose weight! Indeed, more young female athletes
report improvement of appearance than improve-
ment of performance as a reason for dieting
(Martinsen, Bratland-Sanda, Eriksson, & Sundgot-
Borgen, 2010). Thus issues unrelated to sport may
need to be addressed to persuade female athletes to
eat appropriately.
The controversy about whether female athletes can
increase glycogen stores as much as male athletes is
instructive in this regard. An experiment in which
participants consumed diets containing high and low
percentages of carbohydrates found that women
could not do so (Tarnopolsky, Atkinson, Phillips,
& MacDougall, 1995). Subsequently, it was noted
that the total energy intake (per kilogram of body
weight) of the women in that study had been so low
that the amount of carbohydrate they consumed on
the high percent carbohydrate diet was no greater
than the amount consumed by the men on the low
percent carbohydrate diet. Later research showed
that women could, indeed, load glycogen like men
when they ate as much as men (per kilogram of body
weight) (James et al., 2001; Tarnopolsky et al.,
In the 2003 IOC Consensus Conference, the
disruption of reproductive function at energy avail-
abilities 530 kcal kg FFM
was dis-
cussed in some detail and the low bone mineral
density (BMD) found in amenorrhoeic athletes was
represented as being mediated by oestrogen defi-
ciency (Loucks, 2004). Since then, oestrogen-
independent mechanisms by which low energy
availability can reduce BMD have also been
identified (Ihle & Loucks, 2004). As energy avail-
ability declines, the rate of bone protein synthesis
declines along with insulin, which enhances amino
acid uptake, in a linear dose–response manner. By
contrast, the rate of bone mineralization declines
abruptly as energy availability declines below 30
kcal kg FFM
, as do concentrations of
insulin-like growth factor-1 and tri-iodothyronine.
These effects occurred within 5 days of the onset of
energy deficiency, and without a reduction in
oestrogen concentration.
In older adults, fracture risk doubles for each
reduction of one standard deviation below mean
peak young adult BMD. In adolescents, fracture risk
can rise even as BMD increases. Because BMD
normally doubles during the decade of adolescence,
a child entering adolescence with a high BMD
relative to others of the same age can accrue bone
mineral so slowly that adulthood is entered with a
relatively low BMD. Because low BMD is an
aetiological factor in stress fractures, anything that
impairs bone mineral accrual during adolescence is
undesirable. Unfortunately, this is exactly what was
found in a study of 183 interscholastic competitive
female athletes, of whom 93 were endurance runners
and 90 were non-runners (Barrack, Rauh, & Nichols,
2010). The BMD z-scores were similar in runners
and non-runners aged 13–15 years, but were
significantly lower in runners than non-runners at
16–18 years of age.
Also questioned at the 2003 IOC Consensus
Conference was whether energy deficiency and its
clinical consequences were a problem among elite
athletes. Since then a study of 50 British national or
higher standard middle- and long-distance runners
found BMD to be lower in amenorrhoeic runners
and higher in eumenorrhoeic runners compared with
European reference data (Gibson, Mitchell, Harries,
& Reeve, 2004). The duration of eumenorrhoea was
positively associated with spine BMD, and the rate of
bone mineralization was reduced in the amenor-
rhoeic runners. Alone, the Eating Attitudes Test
(EAT) is not clinically diagnostic for eating dis-
orders, but in this study scores on the EAT classified
one of 24 amenorrhoeic runners and none of nine
oligomenorrhoeic runners as having an eating
disorder, while eight amenorrhoeic runners and
three oligomenorrhoeic runners were classified as
practising disordered eating behaviours. This left
63% of the cases of amenorrhoea and 67% of the
cases of oligomenorrhoea unaccounted for by the
EAT test (Figure 2). Similarly, a low body mass
index (518.5 kg m
) failed to account for 67% of
the cases of amenorrhoea and 67% of the cases of
oligomenorrhoea (Figure 3). Another study diag-
nosed low BMD (z-score less than –1) in the lumbar
spine of 34% and osteoporosis (z-score less than –2)
in the radius of 33% of 44 elite British female
endurance runners (Pollock et al., 2010). Reductions
in BMD over time were associated with training
volume. These findings led the authors to recom-
mend that all female endurance athletes undergo
dual-energy X-ray absorptiometry screening.
Ovarian function depends critically upon the
frequency with which the pituitary gland secretes
luteinizing hormone (LH) into the bloodstream, and
LH pulsatility in exercising women depends on
energy availability, rather than energy intake or
energy expenditure separately (Loucks, Verdun, &
Heath, 1998). Furthermore, exercise has no suppres-
sive effect on LH pulsatility beyond the impact of its
energy cost on energy availability (Loucks et al.,
Energy availability in athletes S9
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1998). Reproductive function (Loucks & Thuma,
2003) and bone formation (Ihle & Loucks, 2004) are
impaired abruptly and promptly below a threshold of
energy availability (530 kcal kg FFM
which corresponds closely to resting metabolic rate.
Figure 4 shows sleeping metabolic rate (SMR)
measured by indirect calorimetry in young adult
men (n¼20) and women (n¼17) (Westerterp,
2003). Sleeping metabolic rate is slightly less than
resting metabolic rate by the small energy expendi-
ture associated with being awake. In Figure 4,
the solid regression line relating sleeping metabolic
rate to fat-free mass (SMR [MJ day
]¼2.27 þ
0.091 6FFM [kg]) has a significant y-intercept.
The dashed line through the data and the origin
has a slope of 30 kcal kg FFM
Figure 4 shows, energy availabilities 530 kcal kg
provide less energy than is required
for physiological systems in young adults to function
at rest.
Observational and experimental data indicate that
low energy availability also suppresses Type 1
immunity. The immune system mounts different
defences against two types of pathogens. Type 1
defences are mounted against intracellular pathogens
like viruses, while Type 2 defences are mounted
against extracellular pathogens like bacteria. Endur-
ance athletes frequently suffer upper respiratory tract
infections (URTI) caused by viruses. A survey of all
members of Swedish teams participating in the
Olympic Games of 2002 and 2004 found that those
participating in disciplines emphasizing leanness
made more frequent attempts to lose weight, trained
longer, and reported almost twice as many illnesses,
primarily URTI, during the preceding 3 months
(Hagmar, Hirschberg, Berglund, & Berglund, 2008).
The results of a recent experiment challenge the
hypothesis that Type 1 immunity in athletes might be
suppressed by exercise itself (Lancaster et al., 2005).
Participants expended 2200 kcal of energy by
exercising for 2½ h at 65% of maximal oxygen
uptake ( _
). Replacing just 23% of this energy
with carbohydrate reduced the suppression of Type 1
defences by an average of 65%. Thus, ingesting
sufficient energy and nutrients is vital for supporting
Figure 3. Logistic relationship between the order of menstrual
dysfunction (right ordinate scale: 0 (þ)¼eumenorrhoea; 1
(6)¼oligomenorrhoea; 2 (.)¼amenorrhoea) and body mass
index (BMI) (P50.001 for model). Left ordinate scale is a scale
of probability. The right ordinate scale shows the proportions of
participants in each category. BMI 518.5 ¼underweight. Figure
modified from Gibson et al. (2004).
Figure 4. Sleeping metabolic rate plotted as a function of fat-free
mass (FFM). .¼females; (¼males. The solid regression line
has a significant non-zero intercept. The dashed line is 30 kcal kg
. Figure modified from Westerterp (2003).
Figure 2. Logistic relationship between the order of menstrual
dysfunction (right ordinate scale: 0 (þ)¼eumenorrhoea; 1
(6)¼oligomenorrhoea; 2 (.)¼amenorrhoea) and total EAT
score (P¼0.014 for model). Left ordinate scale is a scale of
probability. The right ordinate scale shows the proportions of
participants in each category. DE ¼classified as disordered eating.
ED ¼classified as eating disorder. Figure modified from Gibson
et al. (2004).
S10 A. B. Loucks et al.
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immune function, and even more so for immune-
compromised individuals, such as those infected
with HIV (Fenton & Silverman, 2008), whose resting
energy expenditure is elevated (Mangili, Murman,
Zampini, & Wanke, 2006). Therefore, HIV-infected
athletes should take special care to reach their energy
and nutrient needs.
Seventeen years have now passed since the first
IOC Consensus Conference on Nutrition. Yet
studies of energy intake and total energy expenditure
continue to report that elite American figure skaters
(Ziegler, Nelson, Barratt-Fornell, Fiveash, & Drew-
nowski, 2001), elite Kenyan runners (Fudge et al.,
2006), and high-performance Canadian athletes in
several sports (Lun, Erdman, & Reimer, 2009) train
in substantial negative energy balance. Depending on
the level of energy availability, such negative energy
balance may either impair or benefit health and
performance. In the current review period, two
studies of elite athletes reported energy intake and
exercise energy expenditure so that their average
energy availability could be estimated. In the week
before a race, the high percent carbohydrate diet of
male Kenyan runners provided an energy availability
of 34 kcal kg FFM
(Onywera, Kiplamai,
Boit, & Pitsiladis, 2004). This energy availability may
or may not have been appropriate depending on their
athletic objectives at the time. If their performance in
that particular race was less important than losing
weight to improve performance in a later race, it was
fine. However, no athletic objective would appear to
justify professional male cyclists training for the Tour
de France 6 months later at an energy availability of
only 8 kcal kg FFM
(Vogt et al., 2005).
Such observations indicate that the diet and exercise
regimens of elite athletes range widely and are
sometimes dangerously energy deficient.
Effects of prolonged exercise on hunger and
energy intake
Eating disorders may be intractable, and weight and
fat loss programmes may be challenging to manage
effectively and safely, but these two origins of low
energy availability in athletes are at least familiar to
sports dietitians. The third origin, the suppression
of appetite by prolonged exercise, appears to be
less familiar. Neglect of appetite as an important
factor in sports nutrition is indicated by the
appearance of the word ‘‘appetite’’ only once
(and then only in a discussion of fluid losses at
high altitude) in the recently revised position stand
on nutrition and athletic performance jointly
adopted by the American Dietetic Association,
the Dietitians of Canada, and the American
College of Sports Medicine (Rodriguez, DiMarco,
& Langley, 2009).
Some of the then available evidence that appetite is
not a reliable indicator of energy needs in athletes
was reviewed at the 2003 IOC Consensus Con-
ference (Loucks, 2004). Shortly afterwards, the
suppressive effect of prolonged exercise on ad libitum
energy intake was clearly demonstrated by the
experiment in which eight lean, untrained men
expended *840 kcal day
by cycle ergometry as
they lived in a room calorimeter for 7 days (Stubbs
et al., 2004). During that week, their ad libitum
energy intake was similar to another week in the
room calorimeter when they did not exercise. This
inadvertent failure to increase energy intake in
compensation for exercise energy expenditure re-
duced their ad libitum energy availability by *10
kcal kg FFM
The participants in that experiment actually
performed the experiment four times, with and
without exercise while consuming equally palatable
62% and 37% carbohydrate diets in a 2 62 cross-
over design. Compared with weeks when the
participants ate the 37% carbohydrate diet, their ad
libitum energy intake declined by *1000 kcal -
on the 62% carbohydrate diet, reducing their
ad libitum energy availability by *16 kcal kg
. Moreover, the suppressive effects
of prolonged exercise and the high percent carbohy-
drate diet were additive. Ad libitum energy avail-
ability declined from *47 kcal kg FFM
when the participants were sedentary on the 37%
carbohydrate diet to *21 kcal kg FFM
when they exercised on the 62% carbohydrate diet
(Figure 5).
These findings in lean, untrained men exercising
in a laboratory confirmed a previous report of a high
Figure 5. The ad libitum energy intake, energy balance, and energy
availability of eight lean men living in a laboratory for 7 days
during an experiment contrasting two diets (50% fat, 32%
carbohydrate [CHO]; and 25% fat, 67% CHO) and two levels
of exercise (840 and 0 kcal day
) (data from Stubbs et al.,
2004). Energy availability was estimated assuming 16% body fat.
Appetite failed to match energy intake to activity-induced energy
expenditure on either diet. Appetite also failed to drive energy
intake on a low fat, high carbohydrate diet to match energy
expenditure at either activity level. These effects were additive.
Reproduced from Loucks (2007) with permission from Adis, a
Wolters Kluwer business (ÓAdis Data Information BV 2007. All
rights reserved).
Energy availability in athletes S11
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percent carbohydrate diet suppressing ad libitum
energy intake in 12 male and 13 female trained
runners living at home (Horvath, Eagen, Fisher,
Leddy, & Pendergast, 2000a; Horvath, Eagen, Ryer-
Calvin, & Pendergast, 2000b). These runners ran 42
miles a week, expending *600 kcal day
for 31
days. They repeated this regimen three times while
consuming equally palatable diets containing 42%,
55%, and 67% carbohydrate. As the percent
carbohydrate content of the diet decreased, ad
libitum energy availability increased from 27 to 34
and 39 kcal kg FFM
in the women and
similarly from 27 to 37 and 42 kcal kg
in the men. Endurance time at
80% _
on a treadmill improved by 18% as the
percent carbohydrate content of the diet was reduced
from 67% to 55%. Interestingly, this reduction in
percent carbohydrate content did not reduce the
amount of carbohydrate consumed, because of the
associated increase in ad libitum energy intake. The
differences in ad libitum energy intake on the three
diets had no effects on body weight or body fat
(Figure 6). The mechanism by which a high percent
carbohydrate diet suppresses appetite has yet to be
investigated, but plausible factors include the greater
bulk and fibre content (Mann et al., 2007) of
carbohydrate-rich foods.
Recently, an even longer experiment simulating
the microgravity in space confirmed the suppression
of ad libitum energy intake by prolonged exercise
(Bergouignan et al., 2010). In this experiment, eight
healthy, lean, untrained women exercised in the
prone position for 50 min at 40–80% _
alternate days during 60 days of bed rest while eight
others did not exercise. Ad libitum energy balance
was 0.7 MJ day
lower in the women who
exercised than in those who did not. Again, there
were no differences in body weight between the two
groups at any time during the 60-day study.
Evidence about the influence of gender on the
suppression of ad libitum energy intake by prolonged
exercise is conflicting. Some researchers have found
the suppression in women to be greater (Staten,
1991) and others smaller (Stubbs et al., 2002a,
2002b) than that in men.
Investigators of the mechanisms that mediate the
suppression of ad libitum energy intake by exercise
recognize that appetite is comprised of two drives.
Hunger, which urges us to begin eating, is stimulated
by the orexigenic hormone ghrelin, whereas satiety,
which leads us to stop eating, is stimulated by several
anorexigenic hormones including peptide YY (PYY),
glucagon-like peptide 1 (GLP-1), and pancreatic
polypeptide (PP). Compared with placebo infusions,
peripheral infusions of ghrelin and PYY at physiolo-
gical concentrations alter food intake, with ghrelin
increasing food intake at a single meal and cumula-
tively over 24 h by 28% (Wren et al., 2001) while
PYY reduces it by 30% (Batterham et al., 2003).
A common experimental protocol for investigating
these mechanisms has been to administer a standard
dinner and breakfast followed by either a prolonged
exercise bout or rest and then an ad libitum buffet
lunch. One such study administered 60 min of
exercise at 66% of maximum heart rate (Martins,
Morgan, Bloom, & Robertson, 2007). The *300
kcal of exercise energy expenditure was followed by
an increase of only *150 kcal in ad libitum energy
intake. At lunchtime, hunger scores and concentra-
tions of ghrelin were no higher after exercise than
after rest, but PP was significantly increased after
Similar results have been found in one-day
experiments on lean, untrained young men who
performed 30 min of exercise at 50% and 75% of
(Ueda, Yoshikawa, Katsura, Usui, & Fuji-
moto, 2009), 90 min of exercise at 68% of _
(King, Miyashita, Wasse, & Stensel, 2010), and a
450-kcal bout of resistance exercise (Ballard et al.,
2009), and on healthy post-menopausal women who
performed 2 h of exercise at 46% of _
Figure 6. The ad libitum energy intake (kcal kg
), energy availability (kcalkg FFM
carbohydrate (CHO) intake (g kg body weight
), 80%
maximal oxygen uptake endurance time, body weight and percent
body fat of 12 female (W) and 13 male (M) endurance-trained
runners living at home for 31 days during an experiment
contrasting three diets (17% fat, 67% CHO; 31% fat, 55%
CHO; and 44% fat, 43% CHO) (data from Horvath et al., 2000a,
2000b). Arrows indicate statistically significant differences. In-
creasing dietary fat from 17% to 31% (reducing dietary CHO from
67% to 55%) increased ad libitum energy intake enough to preserve
carbohydrate intake and increased endurance performance by 18%
without affecting body weight or body fat. Reproduced from
Loucks (2007) with permission from Adis, a Wolters Kluwer
business (ÓAdis Data Information BV 2007. All rights reserved).
S12 A. B. Loucks et al.
Downloaded by [ ] at 22:56 17 January 2012
2010), as well as on male and female endurance
trained runners who ran for 90 min at *60% of
before a 10-km time-trial as fast as possible
on a treadmill after 2 days of carbohydrate loading
and a standardized 70% carbohydrate breakfast
(Russel, Willis, Ravussin, & Larson-Meyer, 2009).
Other experiments have investigated individual
differences in the effects of exercise training on ad
libitum energy intake over a period of 12 weeks
(King, Hopkins, Caudwell, Stubbs, & Blundell,
2008; King et al., 2009). These experiments on
overweight and obese men and women confirmed
the exercise-induced suppression of ad libitum energy
intake mediated by suppressed hunger and increased
satiety that had been found in shorter term experi-
ments, but they also revealed a high degree of
individual variability in weight and fat loss. When
participants were retrospectively classified as com-
pensators or non-compensators based on actual
weight loss compared with the weight loss expected
from exercise energy expenditure, ad libitum energy
intake was found to have increased in the compen-
sators and decreased in the non-compensators (King
et al., 2008). Exercise induced a similar increase in
satiety in both groups, which was even greater after
12 weeks of training than before, but compensators
became progressively hungrier during the experi-
ment (King et al., 2009).
Thus, findings in both trained and untrained
male and female participants consistently demon-
strate that a single bout of diverse forms of exercise
acutely suppresses ad libitum energy intake and that
exercise training chronically maintains the resulting
energy deficiency for many weeks. This effect has
been interpreted to be at least partially responsible
for exercise-induced anorexia (Russel et al., 2009).
Whether some female athletes become hungrier
and increase ad libitum energy intake as their
training progresses, and thereby avoid developing
functional hypothalamic amenorrhoea (like over-
weight participants who do not lose weight on an
exercise training programme), has yet to be
Implications for managing the diets of athletes
The studies of ad libitum energy intake cited above
demonstrate that appetite is an unreliable indicator
of energy requirements for athletes engaged in
prolonged exercise training, just as thirst is an
unreliable indicator of water requirements during a
marathon race. Marathon runners are advised not to
wait until they are thirsty before they begin drinking
during a race. Similarly, athletes who engage in
prolonged exercise training should be advised to eat
by discipline, that is, to eat specific amounts of
particular foods at planned times, instead of waiting
until they are hungry and then eating only until they
are satisfied.
The recommendation for athletes in endurance
sports to consume a diet containing a high percen-
tage of carbohydrates should also be reconsidered.
The original evidentiary basis for this recommenda-
tion was the finding that high carbohydrate intake for
a few days before a high-intensity endurance event
increased glycogen storage and improved perfor-
mance (Costill, 1988). It may be reasonable to
expect endurance athletes to override their appetites
to consume a high volume of a high percent
carbohydrate diet for glycogen loading for a day or
two as a pre-race tactic, but it may not be realistic to
expect them to override the appetite-suppressive
effects of both a high percent carbohydrate diet and
prolonged exercise as a lifestyle. Meanwhile, research
is needed to determine whether the suppression of ad
libitum energy intake by a high percent carbohydrate
diet can be ameliorated by increasing the proportion
of refined carbohydrate in the diet (Mann et al.,
The American Academy of Pediatrics (AAP,
2005), the IOC Medical Commission (Sangenis
et al., 2005), and ACSM (Nattiv et al., 2007) have
all recommended that national and international
governing bodies of sports and athletic organizations
put policies and procedures in place to eliminate
potentially harmful weight loss practices of female
athletes. Procedures and policies were not specified,
because best practices may be sport-specific. These
recommendations followed the establishment of such
policies and procedures by the governing bodies of
US men’s collegiate wrestling in the late 1990s
(Oppliger, Utter, Scott, Dick, & Klossner, 2006) and
men’s international ski jumping in 2004 (FIS, 2004).
The procedures specified by NCAA Wrestling Rule
3 are expensive, intrusive for the athlete, labour-
intensive for athletic trainers, and bureaucratic with
local and national databases, but they seem to have
been effective in reducing unhealthy weight loss
behaviours and promoting competitive equity (Op-
pliger et al., 2006). Based on this success, a call has
gone out for the International Judo Federation (IJF)
to implement regulations to improve weight manage-
ment behaviours among judo competitors, and for
these regulations to be adopted by all National and
Regional Federations (Artioli et al., 2010a).
By contrast, the International Ski Federation (FIS)
employed a very different strategy for preventing
excessive weight loss practices in ski jumpers (FIS,
2004). Instead of policing athlete behaviour, the FIS
removed the motivation for ski jumpers to pursue
excessive weight loss objectives. Ski jumpers have
their height and weight measured at the top of the hill
immediately before their jump, whereupon they are
simply issued skis that are shorter or longer in
Energy availability in athletes S13
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proportion to their body mass index. Shorter skis
reduce aerodynamic lift to compensate for the
advantage a lighter jumper would otherwise gain,
so that a jumper’s success depends on their skill
rather than their body weight. Adoption of this new
rule reduced the percentage of underweight ski
jumpers in the next World Cup competition from
23% to 8% (Muller, Groschl, Muller, & Sudi, 2006).
Replacing body mass index with mass index (MI ¼
body mass divided by the square of sitting height) has
been proposed to further improve the rule (Muller,
Periodization of training may require a period-
ization of energy availability to achieve training
objectives. Experimental evidence indicates that
athletes should follow diet and exercise regimens
that provide energy availabilities of 30–45 kcal kg
while training to reduce body size or
fatness. However, if athletes in other sports are like
judo competitors, personal counselling of athletes by
sports dietitians may not be the most effective way to
moderate athlete behaviour to prevent excessive
energy deficiency. Among seven different types of
advisors for weight management behaviour, judo
competitors ranked dietitians second to last, ahead
only of physicians (Artioli et al., 2010b). The most
influential advisor was the coach. In that context, a
more effective way to modify athlete behaviour may
be for sports dietitians and nutritionists to educate
coaches, using workshops and handbooks that are
specifically targeted at them, about the importance of
energy availability and practical techniques for
managing it.
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... This simplification is pertinent when an energydeficient organism may reduce basal metabolism in an attempt to restore balance, albeit with a suppression of nonimmediately essential physiological functions (Stubbs et al., 2004). Taken together, the concept of EA may be a more useful model for longitudinal adaptation to training as it is closer to an "input" to the body's physiological systems (Loucks et al., 2011). In an athletic population, reduced EA (30-45 kcal·kg FFM −1 ·day −1 ) has been associated with increased risk of impaired physiological functions and physical performance (Loucks et al., 2011). ...
... Taken together, the concept of EA may be a more useful model for longitudinal adaptation to training as it is closer to an "input" to the body's physiological systems (Loucks et al., 2011). In an athletic population, reduced EA (30-45 kcal·kg FFM −1 ·day −1 ) has been associated with increased risk of impaired physiological functions and physical performance (Loucks et al., 2011). Reduced EA has been shown to increase risk of bone stress injuries in both men and women (Papageorgiou et al., 2017), increase risk of menstrual disorders and infertility in women (Loucks et al., 2011), and reduce testosterone levels in men (Burke, Close, et al., 2018;Hackney, 2020). ...
... In an athletic population, reduced EA (30-45 kcal·kg FFM −1 ·day −1 ) has been associated with increased risk of impaired physiological functions and physical performance (Loucks et al., 2011). Reduced EA has been shown to increase risk of bone stress injuries in both men and women (Papageorgiou et al., 2017), increase risk of menstrual disorders and infertility in women (Loucks et al., 2011), and reduce testosterone levels in men (Burke, Close, et al., 2018;Hackney, 2020). Low EA (LEA; ≤30 kcal·kg FFM −1 ·day −1 ) limits the amount of energy used for thermoregulation, growth, cellular maintenance, and reproduction in favor of the more crucial physiological mechanisms that are necessary for survival, with implications for health and performance (Mountjoy et al., 2018). ...
Full-text available
Military training is characterized by high daily energy expenditures which are difficult to match with energy intake, potentially resulting in negative energy balance (EB) and low energy availability (EA). The aim of this study was to quantify EB and EA during British Army Officer Cadet training. Thirteen (seven women) Officer Cadets (mean ± SD: age 24 ± 3 years) volunteered to participate. EB and EA were estimated from energy intake (weighing of food and food diaries) and energy expenditure (doubly labeled water) measured in three periods of training: 9 days on-camp (CAMP), a 5-day field exercise (FEX), and a 9-day mixture of both CAMP and field-based training (MIX). Variables were compared by condition and gender with a repeated-measures analysis of variance. Negative EB was greatest during FEX (−2,197 ± 455 kcal/day) compared with CAMP (−692 ± 506 kcal/day; p < .001) and MIX (−1,280 ± 309 kcal/day; p < .001). EA was greatest in CAMP (23 ± 10 kcal·kg free-fat mass [FFM] ⁻¹ ·day ⁻¹ ) compared with FEX (1 ± 16 kcal·kg FFM ⁻¹ ·day ⁻¹ ; p = .002) and MIX (10 ± 7 kcal·kg FFM ⁻¹ ·day ⁻¹ ; p = .003), with no apparent difference between FEX and MIX ( p = .071). Irrespective of condition, there were no apparent differences between gender in EB ( p = .375) or EA ( p = .385). These data can be used to inform evidenced-based strategies to manage EA and EB during military training, and enhance the health and performance of military personnel.
... The EA is obtained by subtracting exercise energy expenditure from energy intake, adjusted by FFM (Loucks, 2004;Loucks et al., 2011). Each component of the equation relies on accurate measurement tools and a clear definition of what should be measured (Loucks, 2004). ...
... concurrently with the period of growth and development, and may lead to irreparable impairment (Loucks, 2004;Loucks et al., 2011). ...
Energy availability (EA) is calculated by subtracting exercise energy expenditure from energy intake, adjusted for fat-free mass (FFM) obtained using accurate methods, such as dual-energy X-ray absorptiometry (DXA). Unlike DXA, the bioelectrical impedance analysis (BIA) is low in cost, simple and easy to carry out. This study aimed to test the concordance between the calculation of EA using FFM values from four BIA predictive equations and FFM obtained using DXA in female adolescent athletes ( n = 94), recruited via social media. Paired Student’s t test, Wilcoxon test, Lin’s concordance correlation coefficient, root mean square error, limits of agreement, and mean absolute percentage error were used to evaluate agreement between the FFM values obtained by the four SF-BIA predictive equations and DXA. Regression linear analysis was used to determine the relation between FFM values obtained using DXA and the BIA predictive equations. Standardized residuals of the FFM and EA were calculated considering DXA values as reference. The most appropriate model for the FFM (limits of agreement = 4.0/−2.6 kg, root mean square error = 1.9 kg, mean absolute percentage error = 4.34%, Lin’s concordance correlation coefficient = .926) and EA (limits of agreement = 2.51/4.4 kcal·kg FFM ⁻¹ ·day ⁻¹ , root mean square error = 1.8 kcal·kg FFM ⁻¹ ·day ⁻¹ , mean absolute percentage error 4.24%, Lin’s concordance correlation coefficient = .992) was the equation with sexual maturity as a variable, while the equation with the greatest age variability was the one with the lowest agreement. FFM-BIA predictive equations can be used to calculate EA of female adolescent athletes. However, the equation should be chosen considering sex, age, and maturation status. In the case of athletes, researchers should use equations developed for this group.
... In a similar manner, the proportion of players in the poor EA range (<30 kcal/kgFFM/day) was highest on the heavy training load days. This phenomenon where an increase in EEE is not accompanied by an increase in EI has been commonly recorded in female athletes (more so than their male counterparts) [27,28]. In the varsity athlete population specifically, it is difficult to determine whether this discrepancy stems from a lack of knowledge, a lack of preparation, or the inability to prepare for ever-changing schedules as a student-athlete. ...
Full-text available
This study estimated the daily energy intake (EI) and energy expenditure (TDEE) in female varsity rugby union players during a weekly training/game cycle. Fifteen (nine forwards, six backs) players (20.5 ± 0.4 y, 167.1 ± 1.8 cm, 74.9 ± 2.9 kg) were monitored for a 7-day period (one fitness, two heavy training, one light training, one game, and two recovery days) during their regular season. The average EI throughout the week for all 15 players was 2158 ± 87 kcal. There were no significant differences between days, but the lowest EI (1921 ± 227 kcal) occurred on the mid-week recovery day and the highest on game day (2336 ± 231 kcal). The average TDEE was 2286 ± 168 kcal (~6% > EI). The mean energy availability (EA) over the 7-day period was 31.1 ± 3.6 kcal/kg FFM/day for the group. Of the players, 14% were in the optimal EA range (>45 kcal/kg FFM/day); 34% were in the moderate range (≥30–45 kcal/kg FFM/day); and 52% had a poor EA of <30 kcal/kg FFM/day. Carbohydrate (3.38 ± 0.36 g/kg/day, 45% of EI); fat (1.27 ± 0.12 g/kg/day, 37% of EI); and protein (1.38 ± 0.12 g/kg/day, 18% of EI) consumption remained similar throughout the week (p > 0.05). The players consumed 6% less energy than they expended, providing poor to moderate EA; therefore, daily carbohydrate intake recommendations were not met.
... The distinction between athletes and non-athletes must be made in terms of highly variable exercise behavior. Athletes undertaking high training volume and low energy availability may occur without disordered eating due to unintentionally failing to consume sufficient energy (Loucks et al., 2011). In agreement with the present findings, interestingly a high prevalence of orthorexia symptoms via ORTO-15 was also found in the non-athletic healthy eating community on Instagram (Turner and Lefevre, 2017) and yoga practitioners (Herranz Valera et al., 2014;Carmo, 2019, 2021). ...
... The distinction between athletes and non-athletes must be made in terms of highly variable exercise behavior. Athletes undertaking high training volume and low energy availability may occur without disordered eating due to unintentionally failing to consume sufficient energy (Loucks et al., 2011). In agreement with the present findings, interestingly a high prevalence of orthorexia symptoms via ORTO-15 was also found in the non-athletic healthy eating community on Instagram (Turner and Lefevre, 2017) and yoga practitioners (Herranz Valera et al., 2014;Carmo, 2019, 2021). ...
Full-text available
The article aims to summarize the literature about the profile of risk of orthorexia in athletes using the ORTO-15 questionnaire. The search was performed at PubMed, Embase, Web of Science, and Sport Discus databases, using the terms "orthorexia" AND "athletes" with the respective entry terms. A multistage process of selection followed the PRISMA 2020 recommendation. A total of 688 articles were identified, and six studies were available for the final process. The prevalence of risk for orthorexia was assessed by the articles by the ORTO-15 questionnaire and ranged between 38 and 35 points. The comparison between male and female athletes and, athletes and non-athletes was not significant in the six articles. In conclusion, the review highlights that athletes from different sports, included in the review, do not present a risk of orthorexia nervosa considering the cutoff of 40 points, but not 35 points. Also, athletes present the same orthorexic behavior compared to non-athletes, demonstrating that orthorexia is an issue that needs to be considered in the general population. Moreover, a special focus should be given on the ORTO-15 questionnaire, about the sensitivity to diagnose the prevalence of orthorexia, especially in athletes.
... exercise, lays an important issue for the health and success of sports nutrition strategies [12]. Consequently, each athlete/exerciser is different, and there is not an optimal diet that covers the requirements of every athlete at all periods. ...
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The main goal of this narrative review was to incorporate the recent scientific knowledge on the special nutritional needs that are necessary for specific populations of athletes and exercisers (e.g., children, females, vegans) under several training conditions and sports, in addition to proper recommendations for safe administration. The association between nutrition, exercise, and health is an essential part of athletes' and exercisers' competitive and training programs. The quality, quantity, composition, and timing of food consumption are significant to make sure that athletes could train more efficiently to decrease the risk of illness and injury. Athletes who deteriorate their energy intake or use uncontrolled weight loss practices, eliminate certain food groups from their diet, or follow other extreme nutritional philosophies, are at greater risk for micronutrient deficiencies. Fluid intake before, during, and after exercise training or/and competition is significant, particularly in specific circumstances such as hot climates, altitude, etc. Vegetarian and vegan athletes may be at higher risk for low energy, protein, fat, creatine, carnosine, omega-3 fatty acids, as well as essential micronutrients such as iron, calcium, riboflavin, zinc, and β12. Athletes should be adequately informed about the proper use of sports nutrition and ergogenic supplements. These products should only be used after careful evaluation for safety, efficacy, effectiveness, and compliance with relevant legislation. The most significant point to achieving complete and effective nutrition among travelling athletes is planning and preparation while eating properly and hydrated could decrease the potential adverse effects of jet lag and long flights. An effective, healthy, targeted, and complete diet among athletes of different sports should make available sufficient amounts of energy, protein, and carbohydrates depending on the specific sport to make certain sustained exercise training performance and to maintain and improve exercise performance. Article visualizations: </p
... Interestingly, the present study found that the dietary energy deficit of the elderly (≥ 51 years old) is only about 10% (Table 4), which is due to the fact that residents of this age group mostly followed the "local traditional diet" characterized by a high intake of Tsampa (roasted highland barley flour), cultural-specific beverages (Tibetan sweet tea and yak buttered tea), potato, and yak beef (28). Dietary energy is essential for physiological processes, including locomotion, thermoregulation, reproduction, and growth (35). Prolonged periods of energy deficit can negatively impact health and performance, because low energy availability can alter endocrine signaling from the central nervous system (i.e., decreased release of gonadotropin releasing hormone to suppress reproductive function) in response to acute changes in cellular fuel oxidation and peripheral hormones (36), muscle growth and repair, hemoglobin synthesis, bone formation and repair, immune function, and cardiovascular function were affected significantly (37). ...
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Background Dietary intake and nutritional assessing data from a representative sample of adult population living in an agricultural zone on Tibet Plateau are still lacking nowadays. This study aimed to assess the daily dietary intakes and respective food sources in 552 local residents (≥ 18 years old, 277 men and 275 women) living in 14 agricultural counties along the Yarlung Zangbo River on Tibet Plateau. Methods Food consumption data were collected using a validated cultural-specific food frequency questionnaire that contained all local Tibetan foods and analyzed with three fixed factors: gender, age, and region. Nutrient intakes were calculated using Chinese food composition tables. Nutritional gaps and the percentages of participants who had inadequate and excessive nutrient intakes were calculated by estimated average requirement (EAR) cut-point methods. Results Compared with the dietary reference intakes, 68.4% of nutrient intakes were inadequate. Fiber, Ca, I, Zn, Se, and vitamin (Va, Vc, and folic acid) intakes appeared to be particularly deficient. The dietary energy intake was 7838.8 ± 537.1 KJ/d, with 78 and 84% of EAR values for men and women, respectively. The dietary intakes of most nutrients were below the estimated energy requirement/EAR or adequate intake values, while more than 70% of the participants had excessive intake of carbohydrate, especially the elderly (aged ≥ 51 years). The nutritional gap of Cu was more than 300%. Almost 100% of the participants was vulnerable to fiber, Se, and Va shortfalls due to the deficiency in sole food sources. The top five food sources of Se intake were highland barley (34.2%), meat (13%), rice (12.4%), eggs (12.2%), and cultural-specific beverages (7.8%). Eggs (42.1%), tubers (62.2%), vegetables (66.4%), and highland barley (49.7%) were the first contributors of Va, Ve, Vc, and folic acid, respectively. Conclusion The dietary intake of a large sample of Tibetan adult population living in agricultural counties of Tibetan Autonomous Region is alarmingly insufficient. Gender inequality is common, and regional difference is widespread due to rapid urbanization. Young Tibetan adults aged 18–30 years are particularly vulnerable to micronutrient shortfalls and currently facing the risk of nutrition-insecurity-related dietary inadequacy. The respondents who belong to the elderly category (≥51 years of age) are facing the risk of “double burden of malnutrition” characterized by the coexistence of undernutrition, including micronutrient deficiencies and overweight or obesity.
... Similar results were highlighted in scientific literature with evidence on about 60% of judo athletes starting weight cycling before fights at the age of 12-15 and wrestlers at the age of 15.5 ± 2.4 [1,5,12]. It was also shown that the normal growth and development of adolescents were interrupted due to a disturbance in hormone levels induced by continuous by RWL practices [11,15,[31][32][33]. ...
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Rapid Weight Loss (RWL) is a rapid reduction in weight over a short period of time seeking to attain the norm required for a competition in a particular weight category. RWL has a negative health impact on athletes including the significant muscle damage induced by RWL. This study aimed to identify the association between RWL and body composition among competitive combat athletes (n = 43) in Lithuania. Our focus was laid on the disclosure of their RWL practice by using a previously standardized RWL Questionnaire. The body composition of the athletes was measured by means of the standing-posture 8-12-electrode multi-frequency bioelectrical impedance analysis (BIA) and the electrical signals of 5, 50, 250, 550 and 1000 kHz. This non-experimental cross-sectional study resulted in preliminary findings on the prevalence and profile of RWL among combat athletes in Lithuania. 88% of the athletes surveyed in our study had lost weight in order to compete, with the average weight loss of 4.6 ± 2% of the habitual body mass. The athletes started to resort to weight cycling as early as 9 years old, with a mean age of 12.8 ± 2.1 years. The combination of practiced weight loss techniques such as skipping meals (adjusted Odd Ratio (AOR) 6.3; 95% CI: 1.3–31.8), restricting fluids (AOR 5.5; 95% CI: 1.0–31.8), increased exercise (AOR 3.6; 95% CI: 1.0–12.5), training with rubber/plastic suits (AOR 3.2; 95% CI: 0.9–11.3) predicted the risk of RWL aggressiveness. RWL magnitude potentially played an important role in maintaining the loss of muscle mass in athletes during the preparatory training phase (β –0.01 kg, p < 0.001). Therefore, an adequate regulatory programme should be integrated into the training plans of high-performance combat sports athletes to keep not only the athletes but also their coaches responsible for a proper weight control.
Economic models predominate in life history research, which investigates the allocation of an organism's resources to growth, reproduction, and maintenance. These approaches typically employ a heuristic Y model of resource allocation, which predicts trade-offs among tasks within a fixed budget. The common currency among tasks is not always specified, but most models imply that metabolic energy, either from food or body stores, is the critical resource. Here, we review the evidence for metabolic energy as the common currency of growth, reproduction, and maintenance, focusing on studies in humans and other vertebrates. We then discuss the flow of energy to competing physiological tasks (physical activity, maintenance, and reproduction or growth) and its effect on life history traits. We propose a Ψ model of energy flow to these tasks, which provides an integrative framework for examining the influence of environmental factors and the expansion and contraction of energy budgets in the evolution of life history strategies.
Eating disorders (ED), disordered eating (DE) and low energy availability (LEA) can be detrimental to health and performance. Previous studies have independently investigated prevalence of ED, DE or LEA, however limited studies have combined methods identifying risk within female runners. The aim of this study was to identify prevalence of ED, DE and LEA in United Kingdom-based female runners and associations between age, competition level and running distance. The Female Athlete Screening Tool (FAST) and Low Energy Availability in Females Questionnaire (LEAF-Q) were used in a cross-sectional study design. A total of n = 524 responses eligible for analysis were received. A total of n = 248 (47.3%), n = 209 (40%) and n = 49 (9.4%) athletes were at risk of LEA, DE and ED, respectively. LEAF-Q scores differed based upon age (Age: H(3) = 23.998, p≤0.05) and competitive level (Comp: H(1) = 7.682, p≤0.05) whereas FAST scores differed based on age (Age: F(3,523) = 4.753, p≤0.05). Tukey’s post-hoc tests showed significantly higher FAST scores in 18–24 years compared to all other age categories (p≤0.05). Stepwise multiple regression demonstrated age and competitive level modestly predicted LEAF-Q scores (R2adj = 0.047, F(2,523) = 13.993, p≤0.05, VIF = 1.0) whereas age modestly predicted FAST scores (R2adj = 0.022, F(1,523) = 12.711, p≤0.05, VIF = 1.0). These findings suggest early identification, suitable screening methods and educational intervention programmes should be aimed at all levels of female endurance runners.
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Low bone-mineral density (BMD) is associated with menstrual dysfunction and negative energy balance in the female athlete triad. This study determines BMD in elite female endurance runners and the associations between BMD, menstrual status, disordered eating, and training volume. Forty-four elite endurance runners participated in the cross-sectional study, and 7 provided longitudinal data. Low BMD was noted in 34.2% of the athletes at the lumbar spine, and osteoporosis in 33% at the radius. In cross-sectional analysis, there were no significant relationships between BMD and the possible associations. Menstrual dysfunction, disordered eating, and low BMD were coexistent in 15.9% of athletes. Longitudinal analysis identified a positive association between the BMD reduction at the lumbar spine and training volume (p=.026). This study confirms the presence of aspects of the female athlete triad in elite female endurance athletes and notes a substantial prevalence of low BMD and osteoporosis. Normal menstrual status was not significantly associated with normal BMD, and it is the authors' practice that all elite female endurance athletes undergo dual-X-ray absorptiometry screening. The association between increased training volume, trend for menstrual dysfunction, and increased loss of lumbar BMD may support the concept that negative energy balance contributes to bone loss in athletes.
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Judo competitions are divided into weight classes. However, most athletes reduce their body weight in a few days before competition in order to obtain a competitive advantage over lighter opponents. To achieve fast weight reduction, athletes use a number of aggressive nutritional strategies so many of them place themselves at a high health-injury risk. In collegiate wrestling, a similar problem has been observed and three wrestlers died in 1997 due to rapid weight loss regimes. After these deaths, the National Collegiate Athletic Association had implemented a successful weight management program which was proven to improve weight management behavior. No similar program has ever been discussed by judo federations even though judo competitors present a comparable inappropriate pattern of weight control. In view of this, the basis for a weight control program is provided in this manuscript, as follows: competition should begin within 1 hour after weigh-in, at the latest; each athlete is allowed to be weighed-in only once; rapid weight loss as well as artificial rehydration (i.e., saline infusion) methods are prohibited during the entire competition day; athletes should pass the hydration test to get their weigh-in validated; an individual minimum competitive weight (male athletes competing at no less than 7% and females at no less than 12% of body fat) should be determined at the beginning of each season; athletes are not allowed to compete in any weight class that requires weight reductions greater than 1.5% of body weight per week. In parallel, educational programs should aim at increasing the athletes', coaches' and parents' awareness about the risks of aggressive nutritional strategies as well as healthier ways to properly manage body weight.
Children and adolescents are often involved in sports in which weight loss or weight gain is perceived as an advantage. This policy statement describes unhealthy weight-control practices that may be harmful to the health and/or performance of athletes. Healthy methods of weight loss and weight gain are discussed, and physicians are given resources and recommendations that can be used to counsel athletes, parents, coaches, and school administrators in discouraging inappropriate weight-control behaviors and encouraging healthy methods of weight gain or loss, when needed.
Ghrelin and peptide YY (PYY) are newly recognized gut peptides involved in appetite regulation. Plasma ghrelin concentrations are elevated in fasting and suppressed following a meal, while PYY concentrations are suppressed in fasting and elevated postprandially. We determine whether ghrelin and PYY are altered by a low-fat, high-carbohydrate (10% fat, 75% carbohydrate) or moderate-fat, moderate-carbohydrate (35% fat, 50% carbohydrate) diet and; whether these peptides are affected by intense endurance running (which is likely to temporarily suppress appetite). Twenty-one endurance-trained runners followed a controlled diet (25% fat) and training regimen for 3 days before consuming the low-fat or isoenergetic moderate-fat diet for another 3 days in random cross-over fashion. On day 7 runners underwent glycogen restoration and then completed a 90-minute pre-loaded 10-km time trial on day 8, following a control breakfast. Blood samples were obtained on days 4 and 7 (fasting), and day 8 (non-fasting) before and after exercise for analysis of ghrelin, PYY, insulin and growth hormone (GH). Insulin, GH, Ghrelin and PYY changed significantly over time (p < 0.0001) but were not influenced by diet. Ghrelin was elevated during fasting (days 4 and 7), while insulin and PYY were suppressed. Following the pre-exercise meal, ghrelin was suppressed ~17% and insulin and PYY were elevated ~157 and ~40%, respectively, relative to fasting (day 7). Following exercise, PYY, ghrelin, and GH were significantly (p < 0.0001) increased by ~11, ~16 and ~813%, respectively. The noted disruption in the typical inverse relationship between ghrelin and PYY following exercise suggests that interaction of these peptides may be at least partially responsible for post-exercise appetite suppression. These peptides do not appear to be influenced by dietary fat intake.
BORER, K.T. Nonhomeostatic control of human appetite and physical activity in regulation of energy balance. Exerc. Sport Sci. Rev., Vol. 38, No. 3, pp. 114-121, 2010. Ghrelin and leptin, putative controllers of human appetite, have no effect on human meal-to-meal appetite but respond to variations in energy availability. Nonhomeostatic characteristics of appetite and spontaneous activity stem from inhibition by leptin and ghrelin of brain reward circuit that is responsive to energy deficit, but refractory in obesity, and from the operation of a meal-timing circadian clock.
We aimed to evaluate patterns of bone mineral accrual among a cross-sectional sample of female adolescent runners and girls participating in a nonendurance running sport. One-hundred and eighty-three interscholastic competitive female athletes (age 16.0 +/- 0.1 years), 93 endurance runners and 90 nonrunners, completed a menstrual and sports history questionnaire, had their height and weight measured, and underwent a dual-energy X-ray absorptiometry scan for the measurements of body composition and bone mass. For the majority of analyses, the girls were separated into four groups according to their age (13 to 14 years, 15 years, 16 years, and 17 to 18 years). Runners' height, weight, body mass index (BMI), percent body fat, lean tissue mass, number of menstrual cycles in the past year, and months of participation in a non-lean-build/variable-impact-loading sport were significantly lower than mean values for nonrunners. Although bone mass rose at all sites in the nonrunners between the ages of 13 to 14 years and 17 to 18 years, no such increase was noted in the runners. Runners compared with nonrunners exhibited significantly lower body weight and height-adjusted total body and lumbar spine bone mineral content (BMC) values and lower bone mineral density (BMD) Z-score values among the older (16 years and/or 17 to 18 years) but not younger (13 to 14 years and/or 15 years) age groups. These findings suggest that the runners, in contrast to the nonrunners, exhibited a suppressed bone mineral accrual pattern, which supports the notion that female adolescent endurance runners may be at risk for inadequate bone mass gains and thus a low peak BMD.
The effects of prolonged treadmill running on appetite, energy intake and acylated ghrelin (an appetite stimulating hormone) were examined in 9 healthy males over the course of 24h. Participants completed 2 experimental trials (exercise and control) in a randomised-crossover fashion. In the exercise trial participants ran for 90 min at 68.8 + or - 0.8% of maximum oxygen uptake followed by 8.5 h of rest. Participants returned to the laboratory on the following morning to provide a fasting blood sample and ratings of appetite (24 h measurement). No exercise was performed on the control trial. Appetite was measured within the laboratory using visual analogue scales and energy intake was assessed from ad libitum buffet meals. Acylated ghrelin was determined from plasma using an ELISA assay. Exercise transiently suppressed appetite and acylated ghrelin but each remained no different from control values in the hours afterwards. Furthermore, despite participants expending 5324 kJ during exercise there was no compensatory increase in energy intake (24 h energy intake; control 17,191 kJ, exercise 17,606 kJ). These findings suggest that large energy deficits induced by exercise do not lead to acute compensatory responses in appetite, energy intake or acylated ghrelin.