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What is BMI? What is an advantage and disadvantage of using it?
BMI- Body mass index weight (in kg)/height (m^2) Disadvantage: It is not a calculation of percent body fat. Athletes are often miscalculated as overweight. Advantage: easy to calculate, rough estimate of body mass
Body Composition
Used to describe the percent of muscle, bone, and fat in the body -Some body fat is essential -4% in men -10% in women
Does the site of body fat storage matter? Which type is more associated with heart risks?
Abdominal fat or upper body fat (apple)- higher risk for metabolic or cardiovascular disease Gluteofemoral or lower body fat (pear)- lower risk for heart disease
Ways to measure body fat composition: Waist-Hip
Measure waist and hip Too high=men>1.0 and women>.8 Cheap and easy but not that accurate
Bioelectrical Impedence
Resistance to electrical current (fat=terrible conductor) Strengths: fast equipment not expensive Limitations: no food/drink 4 hrs before, no exercise 12 hrs before. Error: 3-4%
Plethysmography (BOD POD)
Air displacement, can do it to anyone Problems: expensive, air flow in room disrupts machine. $30,000
Skinfolds
Somewhat accurate Cheap $250 Error is 3-4% Can't tell fat Tester must be trained
Underwater Weighing
Used to be the most accurate method Problems: difficult to test Air in lungs is problem Anxiety/personal hygiene
Dual Energy X Ray Absorptiometry (DEXA)
Can assess distribution on fat or pattern Radiation low 1/50th chest ray Fully dressed Problem: >100,000
How many kilocalories of excess energy theoretically equal one pound of fat gain?
3500 kcals=1 lb of fat
What are the three main components of energy expenditure?
Resting metabolic rate Thermogenesis Physical Activity
How is energy balance measured by the body? Where is the sensory? Where is the target? How does the sensor communicate with the target?
Measured by body sensors Sensors are located in the brain (hypothalamus) Target is body fat Sensors communicate with the hormone leptin
What hormone functions as the "energy sensor"? Would you expect the levels of that hormone to be high or low in obese people?
Leptin, levels are high in obese people. They become desensitized to the hormone.
Looking at the diagram of responses to weight gain and weight loss, which one of these is the system most sensitive to?
Energy deficit as people become desensitized to leptin when there is a surplus
Why does the hormonal response from weight loss tend to cause people to regain the weight?
When you lose weight, leptin reacts and sends out the signal that you are hungry. Ghrelin is produced by the stomach and creates the feeling that you are hungry
Who is included in the National Weight Control Registry?
A list of people who lost 20+ lbs and kept it off for at least a year. There are around 6000 people registered.
How much physical activity is recommended by the people in the National Weight Control Registry?
About an hour a day
Describe the three ways that exercise can contribute to weight loss maintenance?
a)direct effect of exercise: energy expenditure. 400-800kcal/hr (moderate intensity) b)Post exercise metabolism. Increase in metabolic rate c)RMPR elevated after exercise 2-24 hrs depending on intensity and duration (Increase in muscle mass=increase in RMR)
Does exercise make you hungry? If so, how?
Exercise often suppresses appetite. Exercise stress as well as exercise in heat increase suppression. Exception is swimming (water removes heat) Could be related to vertical motion (disturbance of ghrelin)
Why is exercise as a weight management tool often more effective in men than in women?
Women tend to replace kcals burned more effectively. Women have a higher body fat percentage for reproductive reasons so they tend to hold on to fat more than men.
How do fat-burning dietary supplements (in theory) help control body weight and body fat?
A) Thermogenesis leads to increase in metabolic rate -Usually contains caffeine and something else to compliment caffeine
What happens in the "flight or fight response"? How long does it last? What about ephedra and ephedrine?
Ephedra mimics the hormone adrenaline which instigates "flight or fight" -blood pressure goes up, heart rate goes up -breakdown of glycogen to glucose, triglycerides to fatty acids -epinephrine doesnt last long (10 minutes) -ephedrine mimics epinephrine but lasts much longer (hrs)
Where does ephedra come from? What is made of and what is it supposed to do?
-Ephedra comes from Ma Huang ( a plant in the northern hemisphere) -Ephedra is a mix of ephedrine and psuedoephedrine -Increase energy, burn fat, lose weight, and elevate mood
What combination of factors is most commonly associated with ephedra-related illness?
ephedra, caffeine, and exercise
What is the physiological cause of ephedra related illness?
-elevated blood pressure
What are the physiological responses to ADD/ADHD medications like adderall?
Increased "noise" in the pyramidal neurons of the prefrontal cortex -increased heart rate -faster breathing -high blood pressure
Connection between muscles, muscle fibers, myofibrils, actin, and myosin.
muscles are made up of muscle fibers which are made of myofibril that are made up of actin and myosin. Electrical stimulus by a motor neuron causes sacromeres to shorten and produce force.
What are the major characteristics that distinguish Type I, Type IIA, Type IIB muscle fibers?
Type I: small in diameter, slow twitch fibers, low glycogen and cp, many mitochondria, fatigue resistant Type IIA: Fast contraction, increase in glycogen and creatine phosphate, variable in mitochondria, less fatigue resistant than type I Type IIB- high in glycogen, CP, low in mitochond…
What one factor determines if a muscle is type I, type IIA, or type IIB
Type of training
What is the definition of hypertrophy? Are type I or type II fibers more prone to hypertrophy?
Increase in the size of the muscle due to increase in cell size -type II fibers more prone as they are used for high force production
What is hyperlasia? Does it occur in humans?
The increase in muscle due to an increase in the reproduction rate of its cells. (Does the number of muscle fibers change?) -In some animals (i.e., cats) but no hyperplasia in adult humans as muscles grow by adding protein. -However, fibers can split as they get larger in order to maint…
Muscle fibers may split as they grow. How is that beneficial to the muscle?
-Allows the muscle to get larger while maintaining surface area -Allows access to oxygen and nutrients
What are the three main factors that cause muscle hypertrophy?
1. nutritional 2. hormonal 3. stress
What kind of energy balance is required to gain muscle?
-An energy surplus (Ein>Eout)
How do bodybuilders gain muscle without gaining fat?
-right energy surplus (300kcal/day) -hard resistance training -Cardiovascular training -manipulate hormonal level (supplements, drugs, etc)
What are steroid hormones made from? Where in the cell do they act?
Synthesized from cholesterol Fat soluble and act directly on DNA---> synthesize new proteins
What are anabolic effects? What are androgenic effects?
-Anabolic: muscle building -Androgenic- giving masculine characteristics
What two molecules can testosterone be converted into by the body?
DHT and estradiol
Differences between oral and injectable steroids?
ORAL: -broken down faster -taken more often and in larger quantities -Often methylated---> avoid breakdown in the liver INJECTABLE: -longer lasting effects -dosages are much lower and less often
What are prohormones? How are they supposed to work?
raw materials to use own enzyme to create testosterone Allows the body to create anabolic steroids naturally rather than using a prescription
What is the general consensus regarding the conversion of andro products to and the effects on muscle mass and strength?
Not fully proven, some say there is no effect on strength and others say there is.
How does using anabolic steroid or prohormone products cause a DECREASE in the bodies ownnatural production of testosterone?
When using anabolic agents, high androgen levels lower natural production of testosterone
Does timing of protein intake affect muscle mass?
Yes, consuming protein before and after a workout is more effective for improving muscle mass. 0-2 hrs after workout most effective
Does consuming whey protein increase muscle mass? What is the possible mechanism?
Possibly, quicker absorption of protein leads to more amino acids available for use

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