NUSC 4250 Exam 1

Briefly describe the most significant/obvious change in the 2015-2020 Dietary Guidlines

Follow a healthy eating pattern across the lifespan - meaning all food and beverage choices matter; choice a healthy eating pattern at an appropriate calorie level to help achieve and maintain a healthy body weight; support nutrient adequacy and lower risk of chronic diseases. Example: my plate - regular people eat 3 meals per day vs athletes who eat more than 3 - two breakfasts one before practice banana and peanut butter and one after practice to help restore glycogen stores

Nutrient Density

How much nutrients are in an amount of calories - ex: kind bar, oatmeal with pb, sprinkle of whey or nonfat dry milk

Calorie Density

has a lot of calories in a small portion - ex: snickers, banana with pb

Consider Dietary Guidelines in context of diet design for an athlete - "Athlete/Training Plate" - distribution of macronutrients

Easy training - 1/4 protein, 1/4 whole grain and 1/2 fruits/veg
Moderate training - 1/4 protein, 1/3 fruits/veg, 1/3 whole grains
Hard Training - 1/4 protein, 1/4 fruits/veg, 1/2 whole grains

Define RDA - acronym and classic definition

Recommended Daily Allowance

Classic Def: recommendations to prevent deficiency in healthy individuals

DRI

Daily Reference Intakes

AMDR

Acceptable Macronutrient Distribution Range

Describe the AMDR in the context of flexible diet design for the althete

carbohydrates can range between 45-65%
fats can range between 20-35%
protein can range between 10-35%
This allows the RD to "tweak" the macronutrient distribution between these ranges so the individual can be healthy but be able to preform at their optimal prime
Ex: collegiate athlete may need a higher ration of carbs or be on a higher protein diet vs a sedentary individual who will not need as many carbs or proteins because there is nothing to replenish due to them not working out

Essential Nutrient

A nutrient that has to be in the diet because the body cannot make it

Conditionally Essential Nutrient

Typically non-essential but becomes essential due to metabolic, physiologic and pathophysiologic condition

Absolute intake of macronutrient

Gram amount

Relative intake of macronutrient

Percentage of total energy

Name the 2 nutrition considerations that provide a foundation for the practice of sports nutrition

hydration and calories (energy)

from a physiological perspective, explain why carbs are central to the development of a menu plan for an endurance athlete

Blood glucose gets depleted as the athlete goes through their workout, Additionally, muscle glycogen gets depleted as the athlete uses glyocgen for energy. Therefore the athlete must replete carbs post exercise as to replenish lost muscle glycogen stores and lower blood glucose

"Crossover Concept" is intensity driven and related to oxygen availability. Explain and be specific in terms of the two macronutrients.

The crossover concept says that when oxygen becomes less available you start to burn more carbs than fat. Since the individual is working really hard and the muscle contracts more due to the higher intensity, blood flow to the tissues in reduced, so less oxygen goes to it. In a trained athlete, you can push the crossover curve to the right so the body can work at higher intensity and still burn fat. So, as you become more fit, you can work longer and harder without burning your glycogen stores, allowing you to give yourself that "last push" because you'll have the fuel that you need to keep going.

Cori Cycle in context of the Crossover Concept

The Cori Cycle shuttles lactate from the muscle to the liver where it is converted to glucose via gluconeogenesis using ATP produced from fatty acid metabolism. The glucose then gets released back into the blood and then goes to the muscle to get utilized. Therefore, once you go past the fat burning stage and into carb burning stage, you need carbs to burn. As the muscle does work and lactic acid gets produced, it gets converted to glucose so there is more glucose for the body to burn and you can work for longer.

Explain how chronic glycogen depletion can occur during training or the competitive season

Glycogen gets depleted though training and competing and gets repleted through glycogen synthesis with diet and rest. If the athlete is not eating enough carbs and/or calories, their body stores may not get replenished enough because they need to take whatever is consumed and use it for immediate energy as opposed to muscle glycogen replenishment. Therefore chronic depletion is when an athlete is consistently working and not eating or resting enough to replenish that glycogen so they will no longer be optimal performance.

Recommended range of carbs intake (g/kg) for glycogen repletion

5-10 g/kg

Recommended range of carb intake (g/kg) for endurance athletes

6-8 g/kg

What is the range for relative amount of carbohydrate?

40-70%

Give two specific physiologic reasons as to why the muscle is "primed" post endurance exercise for glycogen repletion

1. increased blood flow to the muscle
2. increased insulin sensitivity

Describe the metabolic benefit of consuming carbohydrate 1-2 hr before an endurance bout to the athlete

The purpose of consuming carbs 1-2 hours before endurance bout is to primary replenish hepatic glycogen stores - it can also contribute to blood glucose

Name the sources of fuel to the muscle during an exercise bout of low to moderate intensity and long duration (-4 hours)

High CHO, low fat, low residue (low fiber), moderate lean protein
Ex: Chicken, beef, salad or fruit

Define "counterregulation"

Glucose conterregulation is the sum of processes that protect against development of hypoglycemia and that restores euglycemia if hypoglycemia should occur - they raise the glucose levels in the blood promoting glycogenosis, gluconeogenesis, ketosis and other catabolic processes

Glucagon, cortisol and ephinephrine

Increase blood glucose

Insulin

Decrease blood glucose

Define glycemic index

The GI is a numerical index that ranks carbs based on their rate of glycemic (their conversion to glucose within the human body). GI uses a scale of 0-100 with high values given to foods that cause the most rapid rise in blood glucose

What are 2 physiological factors contribute to the concept: "Window of Opportunity" after exercise training

1. Increased blood flow to muscles therefore nutrient delivery to muscle maximized
2. increased sensitivity to insulin therefore enhanced glycogen synthesis

Give the significance of chain length - short chain and medium chain

2-6 carbons/8-12 carbons
- do not require micelle for intestinal absorption
- do not require incorporation into micelle for entry into blood
- do not require carrier protein to circulate
- do not require carrier into mitochondria for oxidation
- must be elongated prior to storage, therefore oxidation more likely

Give the significance of chain length - long chain

>14 carbons
- requires micelle, chylomicron, protein carrier in blood, carnitine for transports into mitrochondria
- >16 carbons easily stored

List the 2 primary hormones that "direct" fat mobilization during endurance exercise

Epinephrine (mobilizes fat)
Insulin (stores fat)

Name the 2 enzyme instrumental in fat mobilization to support exercise energetics

Insulin - anabolic - inhibits HSL (lipogenic)

EPI - catabolic - stimulates HSL (lipogenic)

List the sources of fat to the exercising muscle

Intramuscular triglycerides, FFA and glycerol mobilized from adipose tissue
In adipose tissue, TGs are released from the lipid and the glycerol moves into the blood FA are released into the blood (attached to albumin) and then go as free fatty acids into the muscle

Explain how oxygen availability effects fat utilization during exercise

As intensity goes up, oxygen availability becomes limited and fat burning capacity goes down and you burn more carbs instead of fats

Name the cycle associated with fat metabolism that is analogous to the Cori Cycle

Randal Cycle

Cycles that make glucose

Randal, Cori, Alanine-Glucose

Cycles that remove waste

Cori and Alanine-Glucose

Describe how FA available to the muscle affects glucose utilization

When FA avaliablity goes down, the body starts to rely on glucose as fuel. Initially, you will use fat as fuel but once your exercise intensity starts increasing, you switch into using carbs are fuel. The fitter you are, the longer you can exercise with fats as a fuel before switching into carbs as a fuel source

Indirect calorimetry

A technique that measures inspired and expired gas flows, volumes and concentrations of O2 and CO2 allows measurement of O2 consumption and carbon dioxide production. Non-invasive and accurate. The equipment used is known as metabolic cart.

Direct Calorimetry

Having an athlete working in an airtight chamber or human calorimeter. Coils in the ceiling contain water circulating at specific temperature. Athlete has mouthpiece so they can breathe - similar to an enclosed MRI

Define Respiratory Quotient (RQ)

CO2 expired/O2 consumed
Static Measure

Define Respiratory Exchange Ratio (RER)

CO2 expired/O2 consumed
Dynamic Measure

Explain why RQ cn be considered a static measure and RER a dynamic measure?

RQ is considered a static measure because the patient is laying on a bed in a clincal room - fasted and relax which helps figured how many calories they are burning in a fasted state

RER is considered a dynamic measure because it changes over time - Ex: MAX test on a treadmill

Describe how RER might change when athlete runs a race where he or she starts are with a very fast pace, transition to a comfortable pace for an extended period of time and then sprints to the finish

When starting, RER closer to 1 (burning carbs) then RER goes down because burning fat and the RER goes back up at the end to 1 when he/she is sprinting