Most people will experience tiredness or fatigue at some
stage in their lives. Causes may be stress-related or simply due to a lack of sleep. Underlying medical conditions also need
to be ruled out. Fatigue in athletes is often only
of carbohydrate
temporary, caused by an increase in the amount or intensity of
Carbohydrate is an important energy source for athletic
training . Tiredness usually disappears as the body adapts to
performance. Carbohydrates are stored as muscle glycogen, a fuel
the new workload. Fatigue also occurs during exercise and
store that must be constantly replaced. Many athletes think they eat
may be related to various nutritional factors, such as fuel
‘a lot’ of carbohydrate but in reality are eating below their needs. For
example, eating a high carbohydrate meal, such as pasta the night
dehydration. However, tiredness can be a chronic condition
before competition does not necessarily mean that an athlete is
that ne eds further investigation. Adequate nutrition is often
consuming sufficient carbohydrate to fuel their needs. An athlete’s
overlooked as a contributing factor to fatigue. In many cases a
carbohydrate intake needs to reflect their daily training load. An
intake of 3-5 grams of carbohydrate per kilogram of body weight is
change in eating habits can increase energy levels and
enough for athletes undertaking light training, 5-7grams per kilogram for athletes with a moderate exercise program (i.e. 350-
490g in a 70kg person) and as much as 7-12 grams per kilogram
Symptoms associated with fatigue*
(i.e. 490 - 840 g in a 70kg person) per day in an endurance athlete
Chronic low intake of carbohydrate combined with regular training
can result in gradual depletion of glycogen stores and lead to a
feeling of prolonged fatigue. Alternatively, an increase in training
load or exercise intensity can place extra strain on glycogen stores,
while high intensity exercise can result in a loss of appetite.
Depleted muscle glycogen can lead to muscle heaviness and a lack
• Low resistance to infection (colds / flu)
of energy to train, particularly at high intensities. The athlete may
even ‘hit the wall’ and be unable to complete their training session.
Most people store enough glycogen for 90 to 120 minutes of
continuous exercise; however eating too little carbohydrate can
significantly reduce this time. An athlete low in glycogen needs a
See your doctor to check for any underlying medical conditions
reduction in training intensity, or several days rest, as well as an
increase in carbohydrate to replace glycogen stores.
oor food choices
Very low carbohydrate diets can ultimately lead to chronic tiredness,
Active people lead busy lifestyles and often leave little time for
low muscle glycogen and loss of muscle mass. Some athletes claim
ng and food preparation. Insufficient wholegrains, lean
to feel less fatigued when first on these diets. This may be because:
meats and dairy, and too few fruit and vegetables, along with
a) their previous eating habits were worse than the new diet; or b)
a heav y reliance on processed snack foods, can lead to
they obtain a psychological boost from the diet. As carbohydrate is
ongoing fatigue, decreased immunity and general ill health.
also needed to fuel the brain, low carbohydrate diets can result in
Fad diets and nutrition supplements are temporary and do not
poor concentration, depression and mood swings. (See the fact
s long-term nutritional problems. An athlete might use
caffeine-containing foods to suppress fatigue: e.g. coffee,
a and cola drinks. This in itself can set up a cycle of
chronic tiredness. Caffeine can interfere with sleep patterns,
Timing of carbohydrate
making it difficult for the athlete to get to sleep, leading to
Timing of carbohydrate is very important for muscle recovery,
morning tiredness and more caffeine to start the day. A sports
especially when training twice a day. After moderate to high
dietitian can help athletes design a nutritious eating plan that
intensity exercise, muscle doesn’t start replenishing glycogen at a
vide the right balance of carbohydrate, protein and fat
high rate until carbohydrate is eaten, so effective recovery only
and sufficient vitamins and minerals to maximise exercise
starts after eating a carbohydrate based snack or meal. One to 1.2
perform ance at training and competition and promote recovery
grams of carbohydrate per kilogram of body weight (ie 70 - 84g in a
70 kg person) within the first hour after completing exercise is
needed to kick-start optimal fuel recovery (see Table 1). This is
most important when there is only 4 to 8 hours between exercise sessions. If there is longer time between training sessions, then total carbohydrate intake over the whole day is more important.
November 2009
This is a sports nutrition publication of Sports Dietitians Australia.
Phone (03) 9926 1336 ● Fax (03) 9926 1338 ● Email info@sportsdietitians.com.au ● Website www.sportdietitians.com.au
Low energy consumption
Many active people have hectic schedules and simply don’t eat enough during the day. Athletes are faced with the additional
Iron deficienc
challenge of eating to meet the energy needs of training. Those with a large body mass, high training loads or who are growing or trying
Athletes are prone to iron deficiency due to blood loss in sweat, urine and
to increase muscle mass may struggle to eat sufficient food. Hunger
faeces. Females als o have increased losses due to menstruation, while
is not always an ideal guide as exercise can suppress appetite.
those involved in contact sports can have regular injuries that result in
Growth spurts in the adolescent years can also lead to ongoing
bleeding. Drugs such as anti-inflammatories can cause gastro-intestinal
tiredness, particularly in active adolescents. Having energy rich
bleeding, which also increases iron loss. Some athletes have a low iron
foods and drinks available during and after exercise is important to
intake, in particular females and vegetarians. Iron needs are 1.3 to 1.7
times higher for athletes than non-athletes and 1.8 times higher for
vegetarians than meat eaters. Iron deficiency anaemia is less common
than low iron stores. Full blown anaemia results in symptoms such as
Examples of nutritious recovery foods (50g carbohydrate
extreme fatigue and shortness of breath, to the point where the athlete
simply cannot exercise. Decreased iron stores can result in a more
general tiredness with an increase in recovery time, decrease in
250ml – 300ml smoothie or liquid meal supplement
immunity, cold-like symptoms and depression. A blood test is used to
determine iron status. As readings such as haemoglobin and ferritin can
be affected by heavy training, it is often difficult to assess from a single
Meat / chicken and salad roll with 1 piece of fruit
blood test whether iron stores are low. Monitoring of changes to iron
250g of baked beans on 2 pieces of toast
levels with consideration of symptoms and risk factors will give a better
300ml flavoured milk, cereal bar and a piece of fruit
picture of whether insufficient iron is the cause of fatigue. A sports
dietitian can alter an athlete’s food intake to optimise iron intake. (See
Conversely, some athletes restrict their kilojoule (or calorie) intake to
maintain a low body weight for their sport (eg gymnasts, dancers,
rowers). Many female athletes do so to control their weight and body
Vitamin and mineral supplements – the cure for
shape. Low kilojoule diets can eventually lead to a constant feeling
fatigue?
of fatigue due to the body having to survive on too few kilojoules, vitamins and minerals. (See the fact sheet on
There is a widely held belief that our food supply is deficient in most
True nutrient deficiency diseases are not common,
nutrients due to poor soil and processing techniques. Many supplement
but the athlete can suffer sub-clinical symptoms like lowered
companies claim this is the reason why we should take supplements.
immunity, decreased strength due to loss of lean body mass,
However, nutritional analysis of Australian foods shows this is not the
bone maintenance, and poor recovery between training
case. Fatigue and ill health is more commonly caused by an imbalance of
sessions. Athletes on lower energy eating plans may need to choose
carbohydrate, protein and fat. Taking a supplement will do little to reverse
t are nutritious (high in vitamins and minerals) and high in
this problem beyond giving a psychological boost. Of course, if a vitamin
or mineral deficiency is present, taking a supplement may be necessary
to rectify this. A broad spectrum multivitamin and mineral may also act to
protect those who are travelling and cannot eat their normal meals, or
have to limit their food intake to reduce their weight. Elite athletes with a
heavy competition schedule and disrupted meals may also benefit from a
Dehydration
broad spectrum multivitamin and mineral supplement.
Many athl etes do not drink enough fluid to replace their sweat losses
and as a result are chronically dehydrated. Dehydration impacts on exercise performance and may reduce decision making ability and
Summary- reduce your risk of fatigue
. Cramping during exercise may also be a result of
Eat for health. Include plenty of wholegrains, fresh fruit and vegetables,
dehydration. Possible signs of ongoing dehydration are general
lean protein sources, dairy products and healthy fats.
which is worse in hot weather, dry skin, headaches, nausea
Avoid fad diets and those that eliminate carbohydrates or whole food
and an inability to concentrate. One way to monitor fluid status is to
measure body weight on a daily basis and take note of urine volume
Be prepared for eating on the run and after exercise. Sandwiches, rolls,
r. (See the fact sheet on Strongly coloured
smoothies, flavoured milks, yoghurt, fruit and cereal / sports bars are
urine, a small output over the day, and large weight fluctuations from
to the next can indicate poor attention to hydration. Athletes
If you are vegetarian, include meat substitutes like nuts, seeds and
are often encouraged to drink at training, but forget about consuming
fluid throu ghout the rest of the day. Including a drink with every meal Don’t be obsessed with eating ‘good’ foods, avoiding anything
and snack will assist with daily fluid needs. Remember that fluid
containing fat, or limiting your total fat intake to 20grams or less per day.
requirements will be higher during hot weather, if there is an increase
Ensure you are well hydrated every day. Work out your own sweat rate
in training intensity or duration, or after long aircraft flights. Individuals
and come up with an individualised drinking plan.
with high sweat rates should be particularly careful about meeting
Constant travel can wear you out. Plan your ventures and take your
favourite foods such as cereal, sports drink, liquid meal supplement, dried
fruit and nuts, cereal or muesli bars and sports bars.
November 2009
This is a sports nutrition publication of Sports Dietitians Australia. Phone (03) 9926 1336 ● Fax (03) 9926 1338 ● Email info@sportsdietitians.com.au ● Website www.sportdietitians.com.au
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