Sports Nutrition Exam 1

what are amino acids

building blocks of proteins (proteinogenic in human nutrition)

what are BCAAs

Branched Chain Amino Acids (valine, leucine, isoleucine), most abundant in complete protein, primarily used by muscles for energy, and promote muscle protein synthesis

how many amino acids are made into human protein

20

what are essential amino acids

9AAs that must come from diet: phenylalanine, valine, threonine, tryptophan, isoleucine, methioine, histidine, leucine, and lysine (PVT TIM HLL)

what are conditionally essential amino acids

6 AAs needed in certain conditions: arginine, cysteine, glutamine, glycine, proline, tyrosine

what starts protein digestion

chewing and HCL in stomach

what does HCL do to proteins

unfolds them into long polypeptides and activates pepsin

what is pepsin

stomach enzyme that breaks down protein

where is most protein digestion completed

small intestine, with pancreatic enzymes -> ~90% amino acids absorbed

how are AAs transported after absorption

through the portal vein to the liver

what can proteins be used for besides building tissue

catabolized for energy or used to make glucose

in low energy availability, what tissue is sacrificed for energy

skeletal muscle

what must happen before AAs enter energy pathways

deamination (removal of nitrogen groups)

where can AAs enter for energy production

different entry points of the Krebs cycle

what is protein turnover

constant breakdown and rebuilding of proteins

when is turnover highest

during stress or exercise

main protein functions

enzymes, antibodies, pumps/regulators, fluid balance, acid-base balance, and movement

what is the most abundant protein in the body

collagen

what proteins are responsible for movement

motor proteins

where is the code for protein synthesis stored

DNA -> transcribes to mRNA -> translated at ribosomes

what must be present for protein synthesis to complete

all amino acids

if an AA is missing, what happens

skeletal muscle is broken down to supply it

what is the AMDR for protein

10-35% of daily calories

general protein intake guidelines

0.8 g/kg body weight (athletes: 1.2 g/kg+)

what is more accurate: % calories or g/kg

g/kg body weight

what are the highest quality proteins

animal products and soybeans protein isolate

what is whey protein

fast-digesting, high in BCAAs

what is casein protein

slower digesting, similar to whey

what is egg protein

high quality, good for those avoiding dairy

what determines protein quality

amount of protein and digestibility/absorption

functions of protein in athletes

build muscle, promote adaptations, preserve lean mass, strengthen non-muscle tissues

athlete protein intake guidelines

1.2-2.0 g/kg (up to 3 g/kg for physique athletes)

180 lb athlete protein needs

90.9 kg -> 109-182 g protein/day

best way to distribute protein

spread throughout day (0.25-0.3 g/kg per meal), avoid backloading

what increases protein synthesis

exercise novelty, hormones post-workout, injury/illness recovery, positive energy balance

what amino acid triggers muscle protein synthesis (MPS)

700-3,000 mg per meal (with ~10 g essential amino acids)

what are optimal protein sources for MPS

whey, dairy, and other complete proteins

where does fat digestion begin

in the mouth (minor role, lingual lipase)

which organs release enzymes to digest fats

gallbladder (bile salts) and pancreas (lipases)

where are most free fatty acids (FFA) absorbed

small intestine

after absorption, how are fats transported

repackaged into chylomicrons (protein transport vehicles)

can all macronutrients be stored as fat

yes

which enzymes breaks down triglycerides for storage

lipoprotein lipase

which fatty acids must come from the diet (essential)

linoleic acid (omega-6) and alpha-linolenic acid (omega-3)

does everyone have large fat stores

yes

when is fat use highest during exercise

low-intensity exercise

what are other roles of fat

vitamin absorption, hormone regulation, cell membranes, myelin

what does hormone-sensitive lipase (HSL) do

breaks down triglycerides into glycerol and fatty acids

what are the end product of triglyceride breakdown

glycerol and 3 fatty acids

what is the body's main storage form of fat

triglycerides

energy from 1g of fat

9 kcal

saturated fatty acids

solid, no double bonds, ex: butter

unsaturated fatty acids

liquid, double bonds, ex: olive oil

short fatty acid chain length

<6

medium fatty acid chain length

8-12

long fatty acid chain length

>12

two configurations of unsaturated fatty acids

cis and trans

mon common sterol in the body

cholesterol

where is cholesterol found in food

animal products only

which cholesterol is "bad"

LDL (low density lipoprotein)

which cholesterol is "good"

HDL (high density lipoprotein)

where are saturated fats found

meat, cheese, butter

do all saturated fats affect cholesterol the same way

no, effects differ by type

what substitution is suggested to reduce CVD risk

replace saturated fats with polyunsaturated fats

health effect of monounsaturated fats

may decrease LDL and increase HDL

which polyunsaturated fats are essential

omega-6 and omega-3

role of omega-6

epithelial cell function, and gene regulation

role of omega-3 (EPA and DHA)

decrease inflammation, improve vessel function, increase HDL, and decrease triglycerides

how can EPA help athletes

may delay inflammation post-exercise, reduce joint pain, and aid recovery

DHA's role in the brain

improves cell membrane fluidity, decrease inflammation, and decrease blood flow

omega-3s and concussions

may protect against structural damage, improve recovery

how are trans fats made

hydrogenation of unsaturated fats

are trans fats healthy

no (artificial ones increase CVD risk)

are natural trans fats (meat, dairy) as harmful

not significantly in small amounts

what % of daily calories should come from fat (AMDR)

20-35%

how much should come from saturated fats

<2% of total calories

recommended intake of linoleic acid

4.4-13 g/day

recommended intake of alpha-linolenic acid

0.5-1.6 g/day

recommended intake of ecisapentaenoic acid

250 mg/day

recommended intake of docosahexaenoic acid

250 mg/day

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where does carbohydrate digestion occur

mouth (chewing, salivary amylase), stomach, and small intestine villi

why must carbs be broken down into monosaccharides

only monosaccharides can enter the bloodstream

what does a higher glycemic index food mean

causes a higher, faster blood glucose response

how does exercise intensity affect carb use

harder exercise -> greater carb reliance

why do athletes need adequate carb stores

to perform near max intensity exercise

what are 3 primary causes of muscle fatigue

1. muscles can't produce enough force

2. high ATP demand -> incomplete glucose oxidation + acidity buildup

3. muscle energy reserves depleted

how much CHO does the brain consume daily

~120 g/day (~20% of RMR)

what can hypoglycemia or impaired glucose regulation cause

lack of sharpness, mood disorders, possible link to "type 3 diabetes"

what is the AMDR for carbs

45-65% of total energy intake (TEI)

what is the RDA for carbs

130 g/day minimum (for brain function)

carbohydrate needs for pregnancy and lactation

pregnant = 175 g/day; breastfeeding = 210 g/day

what is the max added sugar intake recommendation

<10% of total carbs

daily fiber recommendations

- men: 38 g/day

- women: 25 g/day

- pregnant/lactating: 28-29 g/day

what is the average US fiber intake

~15 g/day

what must accompany increased fiber intake

adequate hydration

health benefits of fiber

binds, toxins, improves elimination, lower cancer risk, increases stool bulk, and binds cholesterol for removal

what are nutritive sweeteners and their risks

provide calories but little nutrition -> overconsumption can cause dyslipidemia, inflammation, diabetes, and obesity

why is high-fructose corn syrup used

cheap, long shelf life, makes food palatable; ~45-55% fructose

what are non-nutritive sweeteners

saccharin, aspartame, ace-k, sucralose, neotame, advantame, stevia, and leu han guo (adds sweetness without calories)