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Sport & Exercise Nutrition

Terms in this set (130)

- main source of energy, especially during high intensity exercise
- proteins sparing, especially during starvation, decreased energy, CHO diets and strenuous exercise
- metabolic primer for fats
- fuel for the CNS - the brain uses blood glucose almost exclusively as fuel
What are the functions of CHO in the body?
- particle size
- degree of cooking/processing
- ripeness of the fruit
- presence of fat or protein
What influences the glycaemic index?
GI greater than 70. Weetbix, cornflakes, glucose, sports drink, honey, white bread, bake potato, watermelon
What are some examples of high GI foods?
GI between 50 - 70. Wholemeal bread, soft drink, brown/white rice, ice cream, ripe banana, mangoes, orange juice
What are some examples of moderate GI foods?
GI less than 50. Porridge, multigrain bread, All Bran, milk, flavoured yoghurt, chocolate, unripe banana, pasta, baked beans, red lentils, apple
What are some examples of low GI foods?
Total 20; 9 essential, 11 non-essential
How many amino acids are there? How many are essential & non-essential?
Leucine, valine and isoleucine
What are the branched-chain amino acids?
- are the building blocks for synthesising tissue e.g. skeletal muscle, connective tissue etc.
- are used for energy production (5-10%)
What are the functions of protein in the body?
0.8 - 1 g/kg BW/d
What are the protein requirements for sedentary men & women?
1.6 g/kg BW/d
What are the protein requirements for elite male endurance atheletes?
1.2 g/kg BW/d
What are the protein requirements for moderate-intensity endurance atheletes?
0.8 - 1 g/kg BW/d
What are the protein requirements for recreational endurance athletes?
1.4 - 1.7 g/kg BW/d
What are the protein requirements for football and other power sports?
1.5 - 1.7 g/kg BW/d
What are the protein requirements for resistance athletes (early training)?
1.0 - 1.2 g/kg BW/d
What are the protein requirements for resistance athletes (steady state)?
Lower than men by approximately 15%.
Are the protein requirements for female athletes higher or lower and by what percentage?
Long-term = aerobic metabolism of fats and CHO
Short-term = anaerobic metabolism of glycogen and blood glucose
Immediate-term = ATP/Pr
What are the substrates used in the long-term, short-term and immediate energy systems?
Muscle glycogen
What is the major source of carbohydrates in the body?
Subcutaneous fat
What is the major source of fat in the body?
A protein source that contains all of the essential amino acids in the right quantities and correct ratio to maintain nitrogen balance and allow tissue growth and repair
What is an complete protein?
Complete protein - beef
Incomplete protein - kidney beans
Complementary protein - Rice dish with beans (legume)
Give an example of a complete protein, incomplete protein and complementary protein food sources.
1. re-utilised for new muscle protein synthesis (MPS)
2. exported to the cell to sustain other functions
3. transaminated and used as a source of fuel
When protein is broken down to amino acids, what are 3 functions the amino acids are then used for?
When muscle synthesis is greater than muscle breakdown
When does muscle hypertrophy occur?
net protein balance = muscle protein synthesis (MPS) - muscle protein breakdown (MPB)
What is the equation for net protein balance?
1. Increase in mitochondrial mass (especially in endurance training)
2. Increase in myofibrillar proteins (especially in resistance training)

An increase in mass could be mitochondrial density or size; if density - more energy able to be produced
A net gain of new muscle proteins achieves two different things. They are:
Resistance training
What type of training increases muscle protein turnover?
Protein turnover occurs locally at the muscle site in:
1. Structural support proteins i.e. collagen
2. Energy producing proteins i.e. mitochondrial proteins
3. Force producing proteins i.e. myofibrillar proteins
Where does protein turnover occur?
True
True or False. After resistance and endurance training, MPS is increased, however if protein is not consumed MPB will occur.
Essential AA content of ingested protein
What is net positive protein balance post-exercise determined by?
Muscle protein synthesis rather than breakdown
Positive net protein balance is mainly due to what?
Protein - protein is required to ensure net positive protein balance post exercise to favour muscle protein synthesis. CHO is also required as it has a protein-sparing effect and will allow all protein to be focussed on MPS recovery, repair, building; CHO also allows re-synthesis of muscle glycogen
What two macronutrients are required for muscle recovery and why?
~20-25g of CHO (0.25g/kg BW) post-exercise every 3 hours
How much CHO is needed for maximal stimulation of MPS post exercise?
Before - may provide time of AAs to become available after exercise
During - may decrease use of AAs already present for fuel (aerobic); also may initiate muscle repair/growth during a long resistance training session
After - essential for MPS and positive net protein balance; should consist of small amounts often: 20g every 3 hours
What are the effects of ingesting protein before, during and after exercise?
soy protein isolate and animal based proteins as they contain all the essential amino acids
What dietary proteins sources are best of MPS?
When all the essential amino acids are presents (especially Leucine) and when the food type is rapidly digested (soy and whey are rapidly digested)
What enhances MPS in terms of type of food eaten
Energy expenditure - energy intake = energy balance
What is the equation for energy balance?
1. Basal/Resting Metabolic Rate (BMR/RMR) - 60-80% EE and is the minimum energy required to maintain vital functions
2. Thermic Effect of Food - 6-10% EE and is the energy donated to the breaking down food ingested
3. Thermic Effect of Activity - 15-40% EE and is the energy used for activity/exercise, often expressed as a multiple of BMR known as a physical activity level (PAL)
What are the components of energy expenditure? Describe.
age, gender, body size & composition especially fat free mass, genetics, phase of menstrual cycle
What influences BMR?
Decrease by ~1000kJ
How much would you need to decrease energy by to lose 1 kg per month
- persistent restriction of energy intake to significantly lower body weight
- intense fear of gaining weight or getting fat
- disturbed way ones body weight or shape is experienced
Describe anorexia nervosa.
- restricting type
- binging/purging type
What are the 2 types of anorexia nervosa?
- recurrent episodes of binge eating
- recurrent episodes of inappropriate compensatory behaviour
- self evaluation influenced by body weight or shape
Describe bulimia nervosa.
Weight making sports e.g. jockey
Sports that view low body weight or body fat as a biomechanical advantage e.g. ballet (?)
Aesthetic sports e.g. bodybuilding, ballet

Eating disorders are thought to be more common in females vs. males, and athletes vs. non-athletes
What type of sports have a higher prevalence of eating disorders?
- micro nutrient and macronutrient deficiences, esp. iron
- low energy availalbility
- bone demineralisation
- increased risk of illness or infection
- cardiac arrythmias
- electrolyte imbalances
- over use injuries and stress fractures
- irregular menstruation
- poor concentration and fatigue
What are some health related consequences of disordered eating?
- decreased muscle contraction time
- decreased muscle power and strength
- decreased aerobic endurance
- increased recovery time
- increase in training days missed due illness or infection
- impairment of oxidative metabolism
- decreased delivery of oxygen to skeletal muscle
- decreased blood flow to skeletal muscle
- decreased reaction time
- fatigue and increased risk of injuries associated with fatigue
- decreased concentration
What are some performance related consequences of disordered eating?
- dispel food myths and encourage healthy eating behaviours through nutrition education and a focus upon improving performance
- de-emphasis on body weight and body composition; light is not always better
- de-stigmatise eating disorders and create a comfortable environment for atheletes to divulge any eating probelms with you
- prevention programs(?)
How can we help prevent disordered eating in athletes?
- restrictive eating
- going to the bathroom after eating frequently
- large amounts of food going missing
- dramatic weight loss or weight gain
- avoiding food-related social gatherings
- relentless excessive exercise
- perfectionism
- strict diet followed by eating binges
What are some warning signs of disordered eating?
An interplay of three different components - energy availability, menstrual function and bone strength (bone mineral density).
Describe the female athlete triad.
Energy availability is defined as energy intake minus energy expenditure. Energy availability can be decreased by decreased intake and increased energy expenditure. Often female athletes do both. Decreased energy availability directly affects bone strength due to affects on metabolic hormones. Decreased energy affects menstrual function through changes of oestrogen which also affects BMD.
Describe the energy availability aspect of the FAT & how it affects the other components
amenorrhea - absence of menstruation
primary amenorrhea - absence of of menstration up to 16 years of age
secondary amenorrhea - absence of menstration when previously had a period
oligomenorrhea/dymenorrhea - irregular menstruation
What is amenorrhea, primary amenorrhea, secondary amenorrhea, and oligo-/dys-menorrhea?
energy availability
What is the main thing that causes a disruption in menstruation function?
Bone stress fractures can be a low grade stress reaction, stress fracture, or a partial or complete fracture. They occur due to repeated sub-threshold stress upon the bone with little time for the bone to repair and recover. The variable related to its occurence are BMI less than 21, menstral dysfunction, energy restriction, training greater than 12 hours per week, low BMD and lean physique sports.
What are bone stress injuries, how to they occur and what variables are related to its occurance?
Requires regular weight bearing exercise
adequate dietary calcium and optimal vitamin status
regular sunlight exposure
favourable hormone environment
What does building healthy bones require?
highly - volleyball, basketball, netball
moderately - running, jogging, hill walking
low - yoga, leisure walking
non - swimming, cycling
What sports are highly osteogenic, moderately osteogenic, low osteogenic and non-osteogenic?
1. Genetic factors - 25 - 40% of our body wt/comp is determined by genetics, for example our height.
2. Environmental factors - social aspects of the sports (e.g. culture of sport), energy intake and macronutrient selection, physical activity and energy expenditure (e.g. increase training to decrease weight), growth and pubertal changes, tapering for competition
What factors influence the ability to achieve the optimal body weight and composition?
(1) passive skill based sports - body fat and wt are largely independent of performance. eg golf
(2) specific weight division sports - usually sports make wt to go down a division days before competing e.g boxing
(3) sports where low body fat and low body wt are considered neccessary for optimal performance - decrease wt, decreased dead weight and increase power to weight ratio - higher performance - e.g. sprinting
(4) sports where body mass is important for power and momentum; wont be penalised as much for increase fat - e.g. rugby
What are the major patterns of body weight and body fat among sports?
- menstrual and endocrine disturbances - FAT
- reduced lean body mass and resting metabolic rate
- illness and immunity
- physiologicall effects and disordered eating
- performance
What are the negative aspects of weight control in athletes?
- individual assessment
- setting realistic targets
- consistent, moderate energy defecit
- strategies to assist with goal achievement
- continued support and periodic assessment
What are the effective counselling techniques to use when assisting athletes to lose body fat?
judo, boxing, lightweight rowing, jockey
What are some examples of weight making sports?
- decrease in plasma volume and increase in susceptibility to heat illness
- decrease in lean tissue
- decrease metabolic rate
- decrease cognitive function
may impact upon bone, nutritional status and performance
What are some of the disadvantages associated with severe and rapid weight loss?
- dehydration and diet
What are the two strategies for weight making?
- fluids and electrolytes and carbohydrate
What are the recovery strategies?
1. depleted iron stores
2. functional iron deficiency
3. iron deficiency anaemia
What are the stages of iron depletion?
only if the athlete has low iron
Does iron supplementation improve performance?
- females
- endurance runners due to foot strike haemolysis
- vegetarians
- adolescents
What are the most common types of people/athletes that have iron deficiency or depletion?
iron play a role in exercise and energy metabolism including:
- synthesis of myoglobin and haemoglobin which transport oxygen to muscle and body
- red blood cell production
- thyroid hormone production
- neural function
- maintaining immune function
What are the roles of iron in the body that are important to athletes?
It depends on the individual - sometimes yes, sometimes no
Is performance affected by iron depletion?
Yes - decrease Hb & Mb production, which means less oxygen being transported to the muscle and around the body; muscle therefore have less ability to use oxygen for its energy systems. Also causes breathlessness and fatigue
Does iron deficiency anaemia effect performance? why/why not?
fatigue, breathlessness, altered resistance to infection, muscle and hormone dysfunction, limited capacity to undertake physical activity
What are the effects of iron depletion?
It is when reduced blood haemoglobin levels reflect an acute response to training (increased). During endurance training the plasma volume increases, and until the red cell mass increases there is anaemia. It is an adaptation process and only occurs when training increases. It is transitional and will correct itself - it does not impair exercise performance.
What is dilutional pseudo-anaemia/sports anaemia?
- iron status and physiological requirements of the individual
- type of iron consumed (non-haem vs. haem)

enhancers of non-haem iron: vitamin C, vitamin A & haem iron (meat protein)
inhibitors of non-haem iron: polyphenols, tannins, phytates, calcium
What affects the bioavailability and absorption of iron?
demographic - elderly, teenagers, female
dietary - low iron intake, vegetarian/vegan, high CHO diet, poor food choices, unbalanced diet, fad diet, excess coffee/tea, low haem intake, low energy diets
social/physical - poverty, food insecurity, alcohol abuse, GIT disease
Describe some demographic, dietary, and social/physical factors that contribute to low iron?
- during periods of growth and strenuous exercise
When are our iron needs increased?
- menstruation (heavy), sweating, GI bleeding or malabsorption
When do we experience iron losses?
Haem iron - red meat, lamb, turkey, pork, chicken, tuna
Non-haem - spinach/kale/silverbeet, iron fortified cereals, sweet corn, milo, bread (iron fortified)
List sources of haem iron and non-haem iron?
No, because the body is efficient at what it does. It will be able to extract all it needs from the foods we are eating. The processes are capped and therefore a bigger person won't need more vitamins or minerals than the next person. The only time they might need more is if they have reduced their energy so much that they are not eating enough food to get all that they need.
Do athletes require more vitamins and minerals that the normal person?
- depletion of glycogen in the active muscle
- GI discomfort or upset
- hypnatremia
- hypoglycaemia
- dehydration
What are the typical nutritional factors associated with debilitative performance?
- adequate carbohydrate intake and rest or light training that does not damage the muscle 24 hours before comp.

Normalised glycogen stores take 24-36 hours with high CHO intake and rest; normalised stores adequate for training less than 60-90 minutes
How do you fuel up for non-endurance events? less than 60-90 min?
carb load
How do you fuel up for an endurance event?
depletion phase - 3-4 days of low CHO diet combined with exhaustive exercise sessions. next phase is 3-4 days high CHO diet and rest from training.

Not the best form as it can cause fatigue, the diet type is complex and there is heavy exercise when tapering is needed
What is the classical protocol for carb loading? Why is it not preferred?
no depletion phase
high intake CHO intake (7-10g/kg/day) for 3-4 days prior
exercise taper

most benefit shown to performance of prolonged moderate-high intensity events lasting longer than 90 minutes
Describe the current regimen for carbohydrate loading
The pre-event meal is CHO-rich, low fibre (low GI), low fat, low-to moderate protein. 1-4 g/kg of CHO 1-4 hours before the event. 3-4 hours may be needed for a large CHO rich meal, and 30-90 minutes for a small CHO rich snack or 'liquid' meal. Practice.
What are the characteristics of the pre-event meal?
To continue to fuel muscle glycogen stores, to increase liver glycogen stores, to prevent hunger but not to cause GI discomfort or upset
What are the goals of the pre-event meal?
- crumpets with jam/honey and glass of flavoured milk
- baked beans on toast
- baked potato with cottage cheese filling and glass of milk
- breakfast cereal with milk
- bread roll with meat/cheese filling and a banana
- fruit salad with fruit flavoured yoghurt
- pasta or rice with a sauce based on low-fat ingredients
What are some examples of pre-event meals suitable for 3-4 hours before exercise?
- fruit
- fruit flavoured yoghurt
- sports bar (check CHO and protein content)
- cereal bar
- cereal with milk
- milk shake or fruit smoothie
- liquid meal supplement
What pre-event snacks would be suitable for 1-2 hours before exercise?
- sports drink, carbohydrate gel, jelly lollies, sports bar, cordial
What foods are suitable to eat if there is less than 1 hour before the event?
- drink 300 - 600mL with the pre-event meal
- drink 300 - 450 mL 15 - 20 minutes before the event
- CHO and electrolyte containing solutions
- remember the fluid content of solid foods
What are some practice times for pre-event hydration?
Exercise must be longer than 60-90 minutes, and the rule of thumb is 30-60 g / hour regardless of size/depending on how much they can tolerate it
How much carbohydrate should an athlete be consuming during exercise?
Distance runner - sports gel or sports drink
elite soccer game - sports drink
distance cycling - banana, hot chocolate, museli bar (anything)
What are examples of CHO you can give to an athlete during an event?
True
True or false - the increase in core body temp and heart rate are directly related to sweat losses?
An increase in core body temp & HR are directly related to sweat losses - which is loss of plasma
a decrease in plasma volume adversley effects thermal regulation and exercise capcity
What are the effects of hyperthermia and dehydration on performance?
It will increase blood flow to the skin and therefore increase thermoregulatory capacity
What is the benefit of consuming fluid during exercise?
heart rate increases, thermoregulation decrease, perceived exertion increases, work capacity decreases and mental capacity decreases.
What is the effect of dehydration upon heart rate, thermoregulation, perceived exertion, work capacity and mental capacity?
dehydration
What does hypernatremia indicate in terms of hydration?
overhydration
What does hyponatraemia indicate in terms of hydration?
True
True or false - sodium stimulates sugar and water in the small intestine and will help maintain extracellular fluid volume?
start hydrated
practise
cool, palatable and carbohydrate containing beverages
early and often
amount of fluid - practiced, comfortable and practical to replace most lost by sweating
- 30 - 60 g CHO per hour
What are some practice times for hydration and carbohydrate consumption during exercise?
- Refuelling: restoration of muscle and liver glycogen stores
- Rehydrating: restoration of fluid and electrolytes lost through sweating
- Rebuilding: protein synthesis for repair and adaptation of muscles
- responses of other systems such as inflammatory, immune and antioxidant
What are the primary things that recovery eating needs to address?
No - muscle glycogen resynthesis takes precedence
Does liver glycogen resynthesis take precedence over muscle glycogen resynthesis post exercise?
Yes
Can glycogen synthesis occur in the absence of CHO?
glycogen synthase
What enzyme is glycogen synthesis dependent upon?
In the 1st 12 hours
In what hours after exercise does maximal glycogen resynthesis occur?
20-24 hours
How many hours are required to normalise muscle glycogen stores provided the mean rate is 5-6 mmol/kg?
7-10 g/kg BW
What is the daily glycogen storage threshold?
1.2g/kg/hr
How much CHO should be consumed post exercise for muscle glycogen storage?
CHO
What is the most important macronutrient for glycogen resynthesis?
- glycogen synthase activation
- exercise increases insulin sensitivity (increase glucose uptake into cells)
- muscle is more permeable to glucose
Why is the 1st hour post exercise the time that maximal glycogen resynthesis/storage is occurring?
High GI CHO's better as they are broken down more quickly and therefore glucose is let into the blood stream more quickly allowing for maximal glycogen resynthesis and storage
Is low GI or high GI carbohydrates best for post-exercise CHO consumption and why?
As immediate fuel needs can be appropriately met
Why is total energy intake important for glycogen storage?
True
True or False - when CHO intake in inadequate, co-ingestion of protein can enhance glycogen storage?
light - 3-5g/kgBW/d
moderate - 5-7/kgBW/d
high - 6-10g/kgBw/d
v. high - 8-12g/kg/d
How much CHO does an athlete need over a full day if they are doing light, moderate, high, and very high intensity activity?
pre - 1-4g/kgBW in 1-4 hours pre-exercise
during - (45-75min duration) - consumed throughout if necessary; 2.5-3 hr duration, 30-60g/kgBW earlier the better
post - 1-1.2g/kgBW in 1st hour
How much CHO should be consumed pre, during, and post exercise?
150% of that lost within 2-4 hours post-exercise; consider sodium as well
How much fluid should be consumed post-exercise?
Because sports drinks contain electrolytes as well as fluids - so they will replace fluid and electrolytes lost. they are also sweet which increases palatability, and promotes further fluid consumption
Why is a sports drink a good option for rehydration post-comp?
Sodium!
What is the main electrolyte lost through exercise?
Negative-
impairs judgement
reduces inhibition
interferes with rehydration
has a direct effect on glycogen stores and leads to inadequate CHO intake
exacerbates soft tissue injuries through vasodilation
may decreases protein synthesis
What are the effects of alcohol on recovery?
Dietary Supplements & Nutritional Ergogenic Aids
Supplements are usually seperated into two categories. What are they?
Group A - supported for use for specific situations in sport; strong evidence base
Group B - needing further research
Group C - no evidence supporting use
Group D - banned and may be contaminated
What are the AIS classifications of supplements and their meanings?
A supplement or a special type of food that help athletes achieve recognised nutritional goals. Useful for providing nutrients that may be difficult or impractical to get through normal eating patterns. Do not enhance performance per se but assist with achieving sports nutrition goals that will enhance performance. Use should be part of a longer nutritional plan not to make up for a poor diet.
What is the definition of a dietary supplement?
sports bar, sports gel, sports drink, liquid meal, multivitamin/mineral, iron supplements, calcium supplements
Give some examples of dietary supplements.
Is a dietary supplements.
Usually a powder or a liquid.
4-8% CHO, 10-30mmol/L sodium
Uses: optimal delivery of CHO and fluid during exercise, post-exercise refuelling & rehydration
Describe the characteristics of sports drinks.
Is a dietary supplements.
25-40g sachet/fluid
65-70% CHO per 25g sachet
Uses:
-supplement a high CHO training diet
-used during exercise
-used post-exercise CHO recovery and CHO loading
Describe the characteristics of sports gels.
Is a dietary supplement.
50-60 g bar; 40-50g CHO, 5-30g protein, vitamin & mineral usually 25-50% NRV
Uses:
- CHO source during exercise
- post-exercise CHO recovery
- supplement high energy/CHO/nutrient diet
-portable nutrition
Describe the characteristics of sports bars.
Is a dietary supplement.
- powder or liquid form
- 1-1.5kcal/mL, 15-20% protein, 50-70% CHO, 500-1000mL supply NRVs for vitamins & minerals
Uses:
- supplement high energy/high CHO/high nutrient diet
- low bulk meal replacement
-post exercise recovery
-portable nutrition for the travelling athlete
Describe the characteristics of liquid meals.
Contain nutrients in excess of dietary intake. Proposed to have an ergogenic effect (work enhancing) on performance through pharmacological (rather than physiological) effects.
What is the definition of an ergogenic aid?
(a) Nutritional ergogenic aids with clear scientific evidence. E.g. creatine, B-alanine, caffeine, bicarbonate, beetroot juice/nitrates
(b) Nutritional ergogenic aids with mixed scientific evidence. E.g. tart cherry juice, carnitine, antioxidants C & E
(c) Nutritional ergogenic aids lacking significant scientific evidence E.g. ribose, glucosamine, CoQ10
(d) Banned or at high risk of contamination with substances that may provide a positive drug test E.g. GH releasers, prohormones, stimulants
What are the gradings of ergogenic aids and their definitions/examples?
Mechanism - creatine is stored in skeleteal muscle; phosphocreatine provides phosphate for rapid resynthesis of ATP which is important in exercise that last 5-10 seconds
Effect - increases work output during repeated 6-30 second bouts of maximal exercise interspersed with 20sec-5min recovery periods
Dose - 5x 5g over 5 days or 3g/d for 1 months; consume with 100g CHO to increase uptake; Maintenance 2-3g/d
Side Effects - wt gain due to fluid accumulation, GI upset, nausea, muscle cramps/strains, headaches
Describe the ergogenic aid creatine in terms of its mechanism, effect, dose and side effects.
Mechanism - CNS effects - perception of effort, muscle conractility, increases fat oxidation and is glycogen sparing
Effects - performance benefits in: end of exercise (mod, int >60 min), high intensity aerobic exercise (20 min), short term high intensity exercise (5 min)
Dose - 3-13mg/kg (1 hr pre-exercise)
Side Effects - tremors, increased HR, headache, impairs post exercise rehydration
Describe the ergogenic aid caffeine in terms of its mechanism, effect, dose and side effects.
Mechanism - 1-7 min of max ex. is limited by a build-up of excess H+ ions; bicarb may speed the efflux of H+ from the muscle and therefore attenutate the adverse effects of H+ ions on energy and force production
Effect - delayed onset of muscular fatigue, and increased ability to work at near max. intensity
Dose - 0.3g of sodium bicarbonate per kg, 1 to 2 hrs pre exercise
Side effects - GI distress (stomach pain, nausea, diarrhoea), consuming plenty of water with bicarb may prevent the diarrhoea
Describe the ergogenic aid bicarbonate in terms of its mechanism, effect, dose and side effects.
PROS:
- true performance benefits
- placebo mediated performance effects

CONS:
- cost
- risk of positive doping outcome
- potential side effects and toxicity
- failure to consider other real performance enhancing strategies
- long term effects (?)
Describe some pros and cons of supplement use.
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