Nutrition

Sports nutrition

specialization within the nutrition field, requires knowledge on both nutrition and exercise science

macronutrients

carbohydrates, proteins, fats

micronutrients

vitamins, minerals

basic nutrients

macronutrients, micronutrients, water

carbohydrates

composed of sugars (compounds made of carbon, hydrogen, oxygen), provide body with energy, found in many foods (grains, fruits, vegetables)

proteins

composed of amino acids (carbon, hydrogen, oxygen, nitrogen), involved in growth and repair of body tissues as well as energy, found in dairy and various meats

fats

lipids, serve as a concentrated form of energy and provides structure to body tissues, concentrated in foods like butter, oils, and meats

vitamins

composed of carbon and other elements, must be obtained from diet, essential to at least one vital process, found in nearly all foods (fruits and vegetables)

water soluble vitamins

B vitamins, C

fat soluble vitamins

A, D, E, K

minerals

composed of elements other than carbon, serve important structural, electrical, and chemical roles in the body

Major mineral classification

requirements > 100 mg/day

Minor mineral classification

requirements < 100 mg/day

water

55-60% of body weight

How does the body produce energy?

Carbs, fats, and proteins are metabolized

Energy is released

ATP is formed

nutrient intake values

Recommended dietary allowances (RDA), Dietary Reference Intakes (DRIs), Estimated Average Requirement (EAR), Adequate Intake (AI), Tolerable Upper Intake Level (UL)

What must nutrition labeling include?

statement of identity, net contents, manufacturer info, ingredient list, nutrition facts panel

Net contents

found on front label, along bottom edge

Indicated the quantity of food in the package

ingredient list

listed in descending order of predominance based on weight

Nutrition facts panel

serving size info, total calories, fat/carb/protein content, vitamin and mineral info, percent daily values (%DVs)

salivary glands

parotid, sublingual, submandibular

secrete saliva, aid in digestion

Stomach

muscular organ, aids in digestion

secretes hydrochloric acid, mucus, digestive enzymes

small intestine

duodenum, jejunum, ileum

aids in digestion and absorption

liver

secretes bile which aids in the digestion of fats

gallbladder

bile from here emulsifies fats

pancreas

secretes bicarbonate and enzymes that digest fats, carbohydrates, and proteins

surface of small intestine

convoluted interior, villi, microvilli

aids in absorption

large intestine

colon, rectum, anus

aids in some absorption

mechanisms of absorption

passive diffusion, facilitated diffusion, active transport, endocytosis

passive diffusion

water and water soluble substances (urea, glycerol) and small lipids move with a concentration gradient, high to low

facilitated diffusion

transmembrane protein carrier changes shape to facilitate entry and exit of some nutrients (fructose), high to low concentration

active transport

minerals, some sugars, and most amino acids move against a concentration gradient with an input of energy (ATP), moves against gradient

endocytosis

cell membrane surrounds small molecules and engulfs them

What helps in digestion of carbohydrates?

mouth, stomach, small intestine, large intestine

Where does absorption occur for carbohydrates?

small intestine through facilitated diffusion (fructose) and active transport (glucose and galactose)

Where do carbohydrates go after absorption?

transport via blood, cellular uptake (insulin and glucose transporters), fates (storage, conversion, energy)

What helps in digestion of fats?

mouth (mastication and lingual lipase), stomach (gastric lipase), small intestines (bile, pancreatic lipase, micelle formation)

Proteins

amino acids linked together

Carbon, hydrogen, oxygen, nitrogen

How do amino acids come together?

through peptide bonds, requires water

protein structures

primary, secondary (coiled or folded), tertiary (3-D shape, winded up)

determines function in body

How many amino acids are there?

20

How many essential amino acids are there?

9, come from the diet

Branch chains from essential amino acids

isoluecine, luecine, valine

How are proteins classified

number of amino acids, composition (complete vs incomplete), quality (high vs low)

High quality protein

complete protein, contains extra amino acids for protein synthesis, good digestibility, usually from animal derived foods

complete protein

contains all essential amino acids

usually from animal-derived foods

Low quality proteins

incomplete proteins, one or more limiting amino acids, usually from plat-derived foods (exception is soy based products- tofu or edamame)

complementing proteins

incomplete proteins that when eaten together provide a full complement of al essential acids

protein functions

tissue building, cell functioning (enzymes), body functioning (hormones, immune function, fluid balance, acid-base balance), energy source, cellular signaling, transport

Nitrogen balance

indicator of nitrogen status and thus protein intake

= nitrogen in - nitrogen out

Protein needed for sedentary individuals

10-20%

0.8 g/kg

Protein needed for athletes

15-35%

1.2-2.0 g/kg

Protein needed for individuals with special circumstances like injury, weight loss, or intense training

25-35%

>2.0 g/kg

Factors that influence protein requirements

total energy intake, desire to lose or gain weight, carbohydrate availability, exercise intensity and duration, training status, dietary protein quality, age, injury status

What should an athlete eat in the hours (4-24) leading up to competition or training?

Balanced high-carbohydrate meals/snacks, familiar foods,

How much protein should be consumed 4 to 24 hours before competition?

depends person to person, what’s available

lean protein sources

3-6 oz turkey, fish, soy

8-12 fl oz dairy

How much protein should be consumed 1 to 4 hours before competition?

Focus should be on carbohydrates, small amounts of lean protein sources preferable

Protein consumption during competition

can serve as an energy source but consumption during exercise is questionable

protein after competition

15 to 25 g protein or 0.25 to 0.30 g protein/kg, essential amino acids, consumed as soon as possible or at least within 2 to 3 hours after competition.

What protein is absorbed more quickly?

Hydrolyzed protein

Vitamins

organic molecules, essential for human survival, water and fat soluble forms

water soluble vitamins

B vitamins, choline, vitamin C

dissolve in water, easily transported in blood, excess is excreted in utine, low potential for toxicity

fat soluble vitamins

A, D, E, K

require dietary fat for transport in blood, excess can be stored in fat tissues of body, higher potential for toxicity