HUNT245

Euhydration

refers to a normal state of body water, ith deviations from this norm producing compensatory responses

Hyperhydration

too much water

a sustained increase in body water, although often transient

hypohydration

too little water (hypo=low)

a sustained decrease in body water

Dehydration

refers to the process of losing water, rather than a state of low body water

water balance

losses

* faecal
* respiratory
* urine
* sweat

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Gains

* metabolic water production
* food
* drink

measures of pre exercise hydration

* urine osmolality
* urine specific gravity
* urine colour
* serum osmolality

pre-exercise guidelines

* start exercise in a euhydrated state
* slowly drink 5-7ml/kg at least 4 hours prior to exercise
* if urine still dark drink further 3-5ml/kg 2 hours prior

effects of dehydration

* depends on the event
* decrease in skill performance
* decrease in mental performance
* opening of the blood brain barrier
* increased perception of effort

ACSM drink guidelines

* try to limit dehydration to

effects of overhydration

* increase in body mass
* urination
* dilution of blood sodium
* hyponatremia

hyponatremia

* blood sodium concentrate

Risk factors of hyponatremia?

* exercise duration >4hrs
* slow speeds
* females
* low body weight
* excessive fluid intakes
* non-steroidal anti-inflammatories
* extreme environments

Pathogenesis

* Excessive water intake
* other etiologies
* hormonal abnormalities
* renal abnormalities
* mobilization of sodium stores

aim of sodium DURING exercise

Assisting with maintenance of

* total body water
* plasma volume
* plasma sodium concentration

recovery guidelines (hydration)

* prepare for the next training session
* exercise

carbohydrate digestion

mouth

* salivary a-amylase hydrolyses dietary starch

Stomach

* the acidity of the stomach temporarily inhibits a-amylase and stops carbohydrate digestion

small intestine

* bicarbonate secretion from the pancreas neutralizes the stomach contents and pancreatic a-amylase continues to digest starch
* several disaccharidase enzymes breakdown disaccharides in the brush border of the small intestine producing monosaccharides (glucose, fructose, etc)

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intestinal carbohydrate absorption

small intestine

* glucose is absorbed in the small intestine via a sodium glucose transporter (SGLT-1)
* fructose is absorbed via a different transporter, GLUT5
* GLU and FRU are transported across the basolateral membrane via the transporter GLUT-2
* GLU and FRU are transported to the liver where fructose is removed from the circulation

Glycogenesis

1. CHO ingestion stimulates the release of insulin from the pancreas
2. insulin stimulates GLUT-4 translocation to muscle membrane
3. glucose-6-phosphate stimulates the production of glycogen

Daily needs (carbohydrate)

* fuel for the muscle and brain during exercise
* low levels of carbohydrate stores are a factor in fatigue and reduced performance
* ensuring that stores are increased result in performance enhancements

factors causing suboptimal intakes (general)

* restricted energy intake


* inadequate practical nutrition skills
* food culture
* poor availability of carbohydrate rich foods
* GI discomfort
* fad diets
* Chaotic lifestyle/travel

factors causing suboptimal intakes (assessment techniques)

* recording errors
* altered intake during recording
* inaccurate recording
* errors in quantification

pre-event meal - considerations

* time of day the event takes place
* length of the event
* climatic conditions
* at home or away from home
* domestic or overseas
* past experience

during exercise - mechanisms of action

* sparing of skeletal muscle glycogen
* prevention of liver glycogen depletion
* prevention of hypoglycemia
* allow high rates of carbohydrate oxidation

during exercise considerations

* start early to preserve glycogen depletion
* consider fluid replenishment too, again start early to avoid excess dehydration
* for both may want small amounts spread across the session to avoid GI distress
* think logistics how easily can it be accessed?
* if fluid what temp may be best
* practice all fluid and food strats in training to avoid impaired race performance

after exercise considerations (carbs)

* time to next exercise session


* intensity of session just completed
* what’s the overall nutrition strat
* demands of the next training session
* tolerance of gut (+ appetite)
* logistics

amino acid structure - AA composition

AA contain carbon, hydrogen and oxygen (as do CHO and fat) but AA also contain nitrogen

amino acid structure - AA structure

1. Carboxyl group
2. amine group
3. variable group (side chain)

each AA’s has a different side chain

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Dipeptide

Composed of 2 AA that are joined by a chemical bond, known as a peptide bond

Polypeptide

Longer chains of AA are known as polypeptides (>20 AA)

Proteins

* proteins consist of many polypeptide chains
* __primary structure__ - determined by the AA sequence
* __secondary structure__ - determined by the interactions between groups (short)
* __tertiary structure -__ determined by interactions between side chains (3D)

Protein Digestion

Stomach

* hydrochloric acid denatures the proteins and pepsin degrades proteins to large polypeptides and AA

Pancreas

* pancreatic enzymes include trypsin and chylotrypsin degrade polypeptides to oligopeptides and AA

Small intestine

* aminopeptidase degrade oligopeptides to peptides and AA
* AA and small peptides are hydrolysed in the cytosol and thus AA enter the circulation

Amino acid metabolism summary

* we cannot store excess AA within the body
* the AA in the blood and ECF represent the AA pool (170g)
* proteins are degraded and synthesized
* this AA pool is constantly turning over (contributes\~20% to BMR)
* AA from the diet can enter this pool as can AA released from liver and muscle
* AA can also be extracted by liver and muscle
* the liver plays a critical role in regulating the composition of the AA pool

Protein Quality

Complete Proteins

* all EAA present

Incomplete Proteins

* plant proteins are deficient in one EAA (lysine, tryptophan, methionine)

Vegetarians

* digestibility
* cell walls of plant proteins (inhibit digestion)
* anti-nutritional factors (inhibit digestion)

Leucine (BCAA)

essential AA

the trigger AA for muscle protein synthesis

what is an essential amino acid

we have to have it in our diets bc we cannot synthesize them from the breakdown of other amino acids in the body

what is a supplement?

A food, food component, nutrient, or non-food compound that is purposefully ingested in addition to the habitually consumed diet with the aim of achieving a specific health and/or performance benefit.

overseas contamination research (supplements)

10-20% of supplements contaminated

supplement testing companies process

Stage 1 - manufacturing critical control audit

stage 2 - ongoing testing (every batch plus additional blind sampling)

Stage 3 - use of logo

if chose supplements need to minimise risk

* “assess the need, assess the risk”
* choose a product with proven efficacy
* ensure product is made to high quality standards
* ensure product has been tested for banned contaminants by a recognized sports anti-doping lab

potential reasons for supplement use

* some nutrients are difficult to obtain from food without excessive intakes
* some essential nutrients are only available in foods some athletes won’t eat
* its difficult to determine the exact amounts of some nutrients in food
* food sources maybe difficult to consume close to, during or after exercise
* some nutrients maybe required in high doses to improve health

creatine

* creatine is a molecule that is produced in the body from amino acids
* creatine stores high-energy phosphate groups in the form of phosphocreatine
* these phosphate groups are donated to ADP to regenerate it to ATP
* creatine is found in some animal-based foods and is most prevalent in meat and fish

how do we get energy from food to power muscle contractions

* food digested
* absorbed in the small intestine
* nutrient travel to cell
* nutrients utilized to create ATP
* ATP = energy currency of the body
* ATP broken down to ADP releasing energy
* Need nutrients to resynthesize ATP
* different exercise results in different pathways for ATP resynthesis

ATP resynthesis pathways

pathway for ATP resynthesis depends on intensity

high-intensity exercise can result in up to a 1000-fold increase in the rate of ATP demand compared to that at rest

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Resynthesis:

break down is stored in chemical containing a high-energy phosphate bond so that the energy released by its breakdown can be used to reconstitute ATP from ADP and Pi:

PCr (creatine) decomposes to creatine plus a phosphate ion plus energy

Australia institute of sport

* the A, B, C, D classification system focuses on sports foods and individual ingredients rather than specific supplement products and brands
* a = strong evidence
* B = emerging evidence: needs more research to be used under monitoring or research protocols
* c = no supportive evidence
* D = banned/high risk

electrolyte balance (hydration)

* major electrolyte lost in sweat is sodium
* 20-80 mmol/l (460-1840 mg/L)
* sweat potassium concentrates \~2-8 mmol/L

Why include sodium (hydration)

Generally included to

* major electrolyte lost in sweat
* improves palatability
* maintains extracellular volume
* may attenuate the decline in blood sodium

palatability

* increasing palatability could increase fluid intake thereby delaying the onset of dehydration
* BUT large amounts of salt decrease palatability
* fluid intakes greatest with 30mmol/L NaCl solution

sodium and thirst

* sodium ingestion may promote fluid intake via increasing thirst
* delay dehydration

Gastric emptying / intestinal absorption

* sodium is important for intestinal absorption
* however, the inclusion of sodium in a drink does not effect gastric emptying or intestinal absorption

Energy pathways

Anaerobic Glycolysis

carbohydrate broken down to release energy to phosphorylate ADP and form ATP

Final product = Lactate and H+

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glycogen - stored form in our muscles and in the liver

can produce 3ATP if it is from glycogen and only two ATP from glycose

Aerobic vs Anaerobic

aerobic = with oxygen

anaerobic = without oxygen

Aerobic metabolism

Oxidative phosphorylation - carbohydrate, protein, fat

Continuous supply of ATP as long as O2 is available

Occurs: Mitochondria

3 Phases:


1. preparation
2. Krebs cycle / Tricarboxylic acid (TCA) cycle - oxidises, removes, electrons
3. Electron transport chain (ETC) - electrons undergo a number of reactions releasing energy to rephosphorylate ADP to ATP

30-32 ATP

Energy metabolism

mainly from plasma glycose and muscle glycogen

* when we are at rest over half (2/3) of our energy comes from fat and a tiny bit from carbs - when we exercise it comes mainly from carbs
* carbs are really important for high intensity or high level sports
* we cant just convert our lipid and fat stores fast enough so we have to rely on carbs
* ever at 75% we do have a little bit of lipids used by majority of the energy is coming from carbs

What happens when insufficient CHO ingested - Dietary CHO and Training

* progressive decrease in muscle glycogen with low carb diet
* glycogen content of muscles can be manipulated by dietary intakes
* glycogen content of the working muscle is a determinant for their capacity to perform heavy exercise

Gastrointestinal distress (carbs)

Gastrointestinal problems occur frequently, especially in long-distance races

* problems seem to be highly individual and perhaps genetically determined

May also be related to the intake of

* highly concentrated carb solutions (gels without water)
* hyperosmotic drinks
* the intake of fibre, fat and protein

Carbohydrate loading

* super-compensated muscle glycogen levels, improve performance 2-3%
* no need for the depletion phase prior to loading
* requirements can vary from around 8 to 12 g-kg-1-day-1 depending on the athlete and their activity
* glycogen storage is associated with weight gain as a result of water retention (approx 3g per gram of glycogen)

Mechanisms of Action - during exercise (carbs)

* sparing of skeletal muscle glycogen
* prevention of liver glycogen depletion
* prevention of hypoglycemia
* allow high rates of carbohydrate oxidation

muscle protein synthesis (MPS)

* varies between different dietary protein sources, depends on post-prandial rise in plasma essential amino acid concentrations (esp leucine)
* Leucine is sensed by sestrin2, which promotes translocation of mammalian target of rapamycin complex 1 (mTORC1) to the lysosome membrane where it becomes activated, resulting in the activation of the downstream anabolic signaling pathways that control muscle tissue protein synthesis
* Plasma amino acid concentrations also provide the necessary precursors for protein synthesis rates to increase
* Ingesting 20–25 g whey protein (providing 2.2–2.7 g leucine) strongly increases muscle protein synthesis rate

absorption of protein

* plant-based whole foods have a lower absorbability when compared with animal-based whole foods
* \~ 85-95% of the protein in egg whites, whole eggs, and chicken is absorbed
* \~ 50-75% of the protein in chickpeas, mung beans and yellow peas in absorbed

why?

* anti-nutritional factors in plant-based protein sources, e.g. fibre and polyphenolic tannins attenuate absorption

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summary

* Animal protein = higher protein quality, is usually considered to be superior to plant protein for building muscle mass
* Healthcare professionals encourage the replacement of animal protein, particularly red meat, with plant protein to help decrease the risk of cardiovascular diseases.
* Plant protein also reduces harm to the environment by decreasing the demand for animal protein, animal farming tends to be more resource intensive with higher greenhouse gas emissions

recovery summary (protein)

The timing and composition of the post-competition or post-exercise meal or snack depend on the level of athlete, length and intensity of the exercise session, and when the next intense workout will occur.

* Eating a source of high quality protein soon after exercise will promote muscle protein synthesis.
* High quality protein particularly from food sources will provide multiple nutrients
* It may help to choose a protein source that is rapidly digested, i.e. whey protein (from foods and drinks).
* Protein powders or liquid meal replacements can be suitable for convenient options

RED-S

relative energy deficiency in sport

what is an eating disorder

* Clinically diagnosable conditions (American Psychiatric Association DSM-V, 2013)
* Eating disorders are illnesses
* Severe disturbances in their eating behaviors and related thoughts and emotions. People with eating disorders typically become pre-occupied with food and their body weight.
* Anorexia nervosa, bulimia nervosa, binge eating etc

eating disorder amongst athletes

Varies by sport higher in

* weight classes (such as rowing), aesthetic sports (such as gymnastics or figure skating)
* sports where having a low body mass is seen as advantageous (such as cross-country or cycling).
* Rates = 25% to 42%,
* Other sports (team sports) 12% to 17%

Common Comorbidities (eating disorders)

individuals affected by eating disorders commonly suffer from other mental health conditions

* depression
* anxiety
* ODC
* and substance use disorder

health consequences of eating disorders

* one of the highest mortality rates of any mental health condition
* death is most often caused by suicide or cardiac arrhythmia - suicide accounts for 20% of deaths among patients with anorexia nervosa and 23% of deaths among patients with bulimia nervosa

treatment for eating disorders

RED-S timeline

1960s

* delayed menarche in undernourished rural girls
* Guula Erdelyi observed changes in menstrual patterns during sport

1970s

* delayed menarche in some athletes
* title IX of the education amendments of 1972

1980s

* first female athlete triad position statement published
* link between amenorrhea and bone mineral density
* links between training volume and thyroid hormones

Female athlete triad (1992)

disordered eating, functional hypothalamic amenorrhea (persistent absence of menstrual cycles at least 3 months), osteoporosis BMD (2.5 SD)

Energy availability

amount of energy available following the energy used for exercise for normal physiological functions per kg of fat free mass

* anything 30 kcal/kg FFM/d is an energy deficiency

Low energy Availability (LEA)

Mismatch between an athlete’s energy intake (diet) and energy expended in exercise, leaving inadequate energy to support the functions required by the body to maintain optimal health and performance.

What happens with LEA → RED-S

* there is insufficient energy available for normal physiological functioning
* the body starts to act as if it were in a state of starvation
* non-essential processes are slowed or halted

symptoms of relative energy deficiency in females

* impaired menstrual cycle
* impaired immune system
* impaired bone density
* reduced female hormones

Relative energy deficiency in male athletes

* decrease in hormone levels
* decrease in protein synthesis - response to resistance training
* direct impact on bone metabolism

Prevalence of LEA/RED-S , NZ survey

* 109 female recreational athletes
* mean age 23.8 years
* 45% at risk for LEA
* every added hour of exercise per week >1.3x risk

Prevalence of LEA/RED-S

* Oligomenorrhea/amenorrhea had been diagnosed in only 12% of athletes


* 50% of athletes not on hormonal contraception who reported symptoms consistent with this diagnosis
* Irregular periods were associated with history of stress fracture
* 73% felt elite sport participation was associated with pressure to have a specific physical appearance, that may be damaging to their overall health
* Barriers to communicating female health issues included male coaches and support staff, and lack of quality health education information.

Reasons for LEA/RED-S (intentional or unintentional)

* clinical eating disorder
* disordered eating
* inadvertent undereating
* intentional weight loss without disordered eating

threats to athletes energy intakes

* complete confusion
* diet gurus (nutrient demonization)
* Quick fixes and pyramid marketing

Orthorexia

an obsession with healthy eating

Why measure body composition

* identify physical characteristics of elite performers
* assess and monitor growth
* monitor training programs/dietary interventions
* determine optimal BC for weight category sports
* monitor the relationship for health and performance

Solutions/considerations for LEA/RED-S

* be aware of vulnerable athletes and have coaches on board and be clear on metrics reported
* focus on performance
* treat data confidentially
* longitudinal monitoring for at risk athletes
* de-emphasise the importance of body composition
* educate on body composition methods and metrics
* let senior athletes with good habits be role models

Recovery of Bone mineral density

Process: years

outcomes:

* increased estrogen continues to inhibit bone resorption
* increased energy status will stimulate anabolic hormones (IGF-1) and bone formation

Recovery of menstrual status

Process: months

Outcomes:

* increased reproductive hormones
* increased estrogen exerts and anti-resorptive effect on bone

Recovery of Energy status

Process: days or weeks

Outcomes:

* increased energy status will stimulate anabolic hormones (IGF-1) and bone formation
* increased energy status will reverse energy conservation adaptations

Advice for clients who may be at risk for RED-S

1. ensure you fuel well around training: cereal, sandwich or porridge before training and sandwiches, pasta and veggies after training are ideal
2. if you are hungry eat
3. Regularly eating throughout the day should help reduce hunger, and also keep you adequately fueled
4. Take at least one rest/recovery day a week

Why do a dietary assessment?

* Nutrition assessment is the basis for a nutritional diagnosis and evaluation
* identify nutritional related problems and their probable causes
* the foundation for nutritional strategies and interventions
* evaluate short and long term health and disease risk

Assessment is not only what someone eats and drinks it may also be

* social, medical and psychological influences on food choices
* may also get energy expenditure data -training and competition
* anthropometrical data (body composition)
* biochemical data

What are you trying to capture? why are you doing it?

* do you need to further communicate with health professionals
* are you going to then create a plan or more information for them?
* when you see them next, summary of what you previously went over with them
* write complete notes for your situation to avoid double handling

Different type of clients? - Under reporter

* wants to lose weight
* everything sounds like its going great
* how can this be happening?

Ask Questions like

* what happens on a bad day
* what does a typical day look like
* what happens when things go wrong

Different type of clients? - Over-reporter

* usually more associated with low energy / disordered eating
* expect it to be over-reported
* intake will sound good but ideally have some form of images to back up portions

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Different type of clients? - the informed/heavily influenced

* clean rater, paleo, vegan etc. May want performance nutrition or potentially weight loss
* may have some meals in a certain way but may still indulge in high calorie foods
* may have poor recovery nutrition
* interested in nutrition - highly motivated

Different type of clients? - the athlete

* can often paint a picture of what they have been told in presentations or what they think you want to know/hear
* context is important, they are being told to see you or have approached you / paying for it?
* try to gain context into their lifestyle - eg body comp history, convos with coaches/trainers etc

Stages of dietrary assessment

stage 1: determine food intake

stage 2: convert food intake into nutrient intake

Stage 3: interpret nutrient and food intake data

Dietary assessment methods - Direct - Retrospective

* dietary history
* 24 hour recall
* food frequency questionnaire
* indicators of dietary quality
* screening

Dietary assessment methods - Direct - innovative technologies

* personal digital assistant
* image-assisted dietary assessment method
* mobile-based technologies
* interactive computer and web-based technologies
* scan - and - sensor - based technologies

Dietary assessment methods - Direct - prospective

* estimated food record
* weighed food record
* duplicate diet model

Food frequency Questionnaire method

Answers questions about how often they consume particular foods/drinks

Use: large scale studies

important that is has been validated and it relates to the population you are looking at

Pros of Food frequency Questionnaire method

* low respondent burden/high compliance
* relatively inexpensive
* high response rate
* usual intakes

Cons of Food frequency Questionnaire method

* must be literate/numerate
* questionnaire design crucial
* relies on memory
* over-reporting is common
* not suitable for individual intakes

Diet recall method

Recall all foods and drinks eaten in the last 24 hours

Use: large studies and clinical setting

application to athletes:

* minimal subject burden
* interview can be scheduled around other daily activities
* multiple recalls to reflect different days
* can be used to study a large number of athletes

Diet recall method - Pros

* collects info on actual intake
* low respondent burden/high compliance
* low cost
* ease and speed of use
* element of surprise