Nutrition, Body Composition & Exercise

Question 1

What is subcutaneous fat?

Answer 1

Fat located under the skin

Question 2

What is visceral fat?

Answer 2

Fat located around the major organs of the body

Question 3

Which type of fat is more associated with disease risk?

Answer 3

Visceral fat - because it is more metabolically active and secretes adipokines

Question 4

What are adipokines?

Answer 4

Adipokines play an important role in regulation of appetite, insulin sensitivity, inflammation and blood vessel function.

Question 5

What happens if you have a large amount of visceral fat?

Answer 5

Greater amounts of visceral fat results in a pattern of adipokine secretion which initiates specific physiological changes that can lead to the development of obesity-related chronic diseases, such as cardiovascular disease & diabetes.

Question 6

What is BMI and how is it calculated?

Answer 6

BMI is a measure that is associated with the risk of early death from all causes. It is calculated by dividing weight by height squared.

Question 7

What are the BMI ranges?

Answer 7

<18.5 = underweight
18.5-25 = normal
25-30 = overweight
>30 = obese

Question 8

What are the limitations of BMI?

Answer 8

The main limitation of BMI is that it does not provide a measure of body composition and may classify
very muscular people as overweight. It also does not classify where the fat mass is distributed, which can have a significant influence on disease risk.

Question 9

What is waist circumference?

Answer 9

An individual’s waist circumference is the most practical way to estimate body fat distribution. As waist circumference increases, disease risks increases because greater visceral fat in the abdomen is associated with increased risk of obesity-related diseases such as cardiovascular disease and diabetes.

Question 10

What waist circumference measurements indicate a risk of cardiovascular conditions?

Answer 10

Women with a waist circumference of greater than
88 centimetres and men with a waist circumference of greater than 102 centimetres have a high risk of obesity-related health problems.

Question 11

What is waist:hip ratio? Out of waist circumference and waist:hip ratio which measure is more effective?

Answer 11

The waist-to-hip ratio can also be used to
classify disease risks. The ratio requires an additional measurement step (measuring the hips and the waist) compared with just measuring waist circumference, but it does not provide any more precise estimate of disease risk. Therefore, waist circumference is usually
preferred over the waist-to-hip ratio.

Question 12

What are some limitations of utilising the waist circumference measure?

Answer 12

Waist circumference is a convenient method of
estimating disease risk, but it can vary due to measurement error and isn’t always an accurate predictor of visceral fat because other tissues and organs will also influence the size of the waist circumference.

Question 13

How are skinfolds utilised to measure body composition?

Answer 13

Skinfolds estimate body fat percentage by using a calliper to gauge the thickness of a fold of
skin from several “sites” to then compare measures with standards.

Question 14

How is bioelectrical impedance utilised to measure body composition?

Answer 14

Bioelectrical impedance measures body fat by using a low-intensity electrical current.
Because electrolyte-containing fluids are found primarily in lean body tissues and are readily able to conduct an electrical current, the leaner the person, the less resistance to the current. This measurement of electrical resistance is then used to estimate the percentage of body fat.

Question 15

How is air displacement plesythmography utilised to measure body composition?

Answer 15

Air displacement plethysmography estimates body composition by having a person sit
inside a chamber while computerised sensors determine the amount of air displaced by the
person’s body. The provides an estimate of the volume of the body. Body density can then
be calculated and body fat percentage estimated because fat tissue is less dense than lean
tissue.

Question 16

How is hydrodensitometry utilised to measure body composition?

Answer 16

Hydrodensitometry measures body density by weighing the individual first on land and then
again whilst submerged in water. The different in weights provides a volume measure. The
weight and volume measures are then used to determine body density.

Question 17

How is Dual energy X-ray Absorptiometry (DEXA) utilised to measure body composition?

Answer 17

Dual energy X-ray absorptiometry (DEXA) is the gold standard for measuring body
composition. It is able to measure the density of different body tissues through multiple
cross-sectional segments. It is also able to provide a specific measure of the amount of
visceral fat.

Question 18

What is energy availability?

Answer 18

Energy availability is a concept used in sports nutrition to determine whether energy intake
is likely to be insufficient to sustain healthy physiological functions during periods of high
energy expenditure.

Question 19

How is energy availability calculated?

Answer 19

Energy availability is calculated by subtracting the energy expendedduring an athlete’s exercise training from the total dietary energy intake. It is usually
expressed in kilojoules or calories relative to an individual’s fat free mass.

Question 20

What is energy availability indicative of?

Answer 20

it provides an indication of the amount of energy remaining for normal physiological function after the
demands of exercise have been met.

Question 21

What happens as a result of low energy availability?

Answer 21

Low energy availability in athletes can lead to a
condition known as relative energy deficiency in sport (RED-S) which is associated with the following negative consequences for athletes:
- Decreased endurance performance
- Increased injury risk
- Decreased training response
- Impaired judgement
- Decreased coordination
- Decreased concentration
- Irritability
- Depression
- Decreased glycogen stores
- Decreased muscle strength

Question 22

What are carbohydrates?

Answer 22

Carbohydrate is a nutrient that provides energy for exercise, particularly high intensity exercise. Carbohydrate in both endogenous (stored in the body) and exogenous (consumed in foods and beverages) forms can be used as fuel during exercise.

Question 23

How does carbohydrate consumption contribute to energy expenditure?

Answer 23

The contribution of carbohydrate breakdown to total energy expenditure increases as the intensity of exercise increases.

Question 24

What are carbohydrates helpful for?

Answer 24

Carbohydrate is also helpful for the central nervous system and may influence concentration, perceptions of fatigue during exercise and pacing strategies.

Question 25

How should carbohydrate intake be regulated?

Answer 25

Carbohydrate intake should be manipulated to suit the goals of individual athletes at any given point in their training schedule and periodisation of carbohydrate intake may promote positive adaptations to training.

Question 26

How does consuming carbohydrates assist with exercise?

Answer 26

Consuming carbohydrate during exercise is associated with improved endurance performance, particularly during exercise lasting two hours or more. Carbohydrate ingestion is likely to provide additional fuel for exercise and delay the depletion of muscle glycogen stores.

Question 27

What happens when carbohydrate intake exceeds 60 grams per hour?

Answer 27

Once carbohydrate intake during exercise exceeds 60 grams per hour, it is important that specific types of
monosaccharides are consumed. This is because glucose absorption in the gut is the rate limiting step for exogenous glucose to be used as a fuel by the muscle. Consuming other monosaccharides in combination with glucose, will allow more carbohydrate to be absorbed and then used for energy to fuel muscle contractions.

Question 28

What is fat?

Answer 28

Fat is the largest source of stored energy in the body and one of the key metabolic adaptations to endurance training is an increase in the ability to oxidise fat for energy.

Question 29

When does the maximal rate of fat oxidation typically occur?

Answer 29

The maximal rate of fat oxidation typically occurs at an exercise intensity of approximately 50%
VO2max. However it is important to note individual variations.

Question 30

How can we use fat as an energy source for exercise?

Answer 30

The ability to use fat during exercise can be manipulated through both exercise training and dietary interventions, however fat is not quite as efficient as carbohydrate when used as a fuel during exercise. Slightly more energy per litre of oxygen consumed is
generated when carbohydrate is used by the muscle compared with when fat is used by the
muscle.

Question 31

How much fat needs to be consumed in order to reach a state of keto-adaptation?

Answer 31

A very high fat diet providing >80% of energy from fat with very little carbohydrate (<50g/day) is required to be consumed for a few weeks in order to achieve a state of ketoadaption. This means the body is adapted to use predominantly fat for activities requiring
energy and is also able to tolerate relatively low levels of blood glucose due to the availability of ketones for the central nervous system.

Question 32

What does keto-adaptation facilitate?

Answer 32

This adaptation facilitates very high rates of fat oxidation during exercise which may be an advantage to performance in events lasting several hours such as ironman triathlons, particularly if exogenous carbohydrate is not available or not well tolerated. While the benefits of high fat diets for endurance
athletes are theoretically plausible, the evidence for benefit is limited at this stage.

Question 33

What is the importance of protein in terms of exercise?

Answer 33

Protein is often considered in the context of strength and power based sports because of protein’s relation to muscle mass, however, protein requirements of endurance athletes are also increased due to the high energy expenditure during endurance exercise.

Question 34

What are the daily protein recommendations for endurance athletes?

Answer 34

Daily protein recommendations for endurance athletes range from 1.0-1.6g/kg body mass depending on
exercise intensity and duration.

Question 35

When is the best time to consume protein?

Answer 35

Studies show that consuming protein after a bout of resistance exercise can enhance subsequent muscle protein synthesis. The degree to which protein synthesis is augmented is determined by the amount, type and timing of protein intake.

Question 36

How much protein stimulates optimal muscle protein synthesis?

Answer 36

About 20-25g of protein appears to stimulate optimal muscle protein synthesis after an acute bout of resistance exercise, although up to 40g may be required for larger athletes. Consuming 20-25g protein
every 3-4hours has been shown to provide the best stimulus for protein synthesis throughout the day when compared with larger, but less frequent intakes or smaller, but more frequent intakes.

Question 37

Which type of protein is best to consume in order to ensure optimal muscle protein synthesis?

Answer 37

Protein that contains all the essential amino acids; is high in the amino acid leucine and is rapidly
absorbed after digestion appears to be best for optimising protein synthesis in the muscle. A
good example of a protein that has these characteristics is whey protein from milk. Optimal
gains in muscle mass and strength during resistance training are achieved when daily protein intake is approximately 1.6-2.0g/kg body mass, which is approximately double the requirements of sedentary individuals.

Question 38

Compare micronutrient requirements of athletes to non-athletes.

Answer 38

Micronutrient requirements of athletes and exercising individuals are likely to be higher than non-athletes. The additional requirements for many micronutrients are easily met through the increased food intake associated with additional need for energy and
macronutrients. However, specific micronutrients such as iron, calcium and vitamin D can be challenging for athletes.

Question 39

Why is iron consumption so important for athletes?

Answer 39

Exercise training increases iron requirements. The exact amount of additional iron required by athletes is not known precisely and depends on the specific circumstances of the individual such as the training load, training type and/or location (e.g. altitude). Athletes with low iron status or deficiency may benefit from high dose iron supplementation, complemented by close monitoring and the support of a health professional. It is prudent to recommend that athletes consume a variety of iron rich foods in order to prevent low iron status. Additionally, regular monitoring of iron status in higher risk groups such as female
endurance athletes should be considered if available.

Question 40

How is iron lost?

Answer 40

Iron is lost through sweat, increased red
blood cell turnover during injury, training at higher altitudes and menstrual losses. Running,
which is involved in many sports, also causes some damage to red blood cells in small
capillaries due to the foot repeatedly striking the ground.

Question 41

Why is calcium important for athletes?

Answer 41

as bone mineralisation increases, the need for calcium also increases. This is particularly important for adolescent athletes who are growing.

Question 42

What is vitamin D and what is its role?

Answer 42

Vitamin D is an important nutrient for bone health, plays a role in immune function and is
also involved in muscle growth and repair processes.

Question 43

What do low serum concentrations of vitamin D result in?

Answer 43

Low serum concentrations of vitamin D

are associated with impaired muscle function.

Question 44

Why is antioxidant supplementation not currently recommended for athletes?

Answer 44

Supplementation with antioxidants during periods of exercise training
appears to blunt adaptations to training and is currently not recommended for exercising
individuals. Although during acute periods of very high training or competition stress,
antioxidant supplementation may offer some short-term benefit.

Question 45

Why is fluid consumption important?

Answer 45

As dehydration increases, there is a reduction in
physical and mental performance, increase in heart rate and body temperature and an
increased perception of how hard the exercise feels. It is also important for athletes not to
over-hydrate as this may lead to gastrointestinal upsets, carrying excess weight (as fluid) or
more severe outcomes such as hyponatraemia.

Question 46

What is the effect of dehydration on exercise performance?

Answer 46

The effects of dehydration on exercise performance is complex as fluid losses during
exercise can vary significantly between individuals. Studies have found that fluid losses
equivalent to 2% of body mass appear to have negative effects on endurance capacity
during exercise tasks performed at a fixed intensity. However, adverse effects on endurance
time trial performance may not occur until 4% of body mass is lost. This adds complexity to
creating standardised fluid intake guidelines

Question 47

Why is it difficult to develop fluid intake guidelines?

Answer 47

Specific guidelines for fluid intake during exercise are difficult to develop because there is so
much variation between individuals.

Question 48

How much fluid is required to be consumed post-exercise?

Answer 48

It is recommended to consume around one and a half times
the fluid lost during exercise, as sweat losses continue after exercise and not all of the fluid
consumed is retained by the body.

Question 49

What is the best fluid to consume post-exercise?

Answer 49

Fluids high in energy move through the gastrointestinal system at a slower rate. This
prevents a rapid dilution of plasma sodium concentration and reduces the stimulation of
fluid excretion that occurs when high volumes of fluid are absorbed quickly. Milk is one of
the best fluids to consume after exercise as it enhances fluid retention due to it containing
sodium, protein, carbohydrate and a relatively high overall energy content. A similar effect
can be achieved by combining energy dense foods with plain water.