HK 352 Exam 1

metabolism

the sum of chemical responses with catabolic and anabolic processes

catabolism

breakdown

anabolism

buildup

energy

the capacity to produce force, perform work, or generate heat

efficiency(%) =

(work output/energy input) x 100

things that control enzyme activity include (7)

• coenzymes

• substrate concentration

• temperature

• pH

• enzyme #

• allosteric modification

• covalent modification

3 main energy systems include:

1. ATP-PCr

2. Glycolytic

3. Oxidative

explain the ATP-PCr System

• prevent energy depletion by forming more ATP

• instantaneous process but substrate quickly depletes

• occurs in cytosol

• provides energy for 3-15s

ex. powerlifting

what is the ATP:ADP ratio in ATP-PCr?

6:1

glycolysis

breakdown of glucose, can be aerobic or anaerobic

glycogenesis

process by which glycogen is synthesized glucose to be stored in liver/muscle

glycogenolysis

process by which glycogen is broken down into glucose-1-phosphate to be used by muscle

explain glycolysis

• needs 12 rxns to breakdown glycogen into ATP

• glycolysis is anaerobic

• occurs in cytosol

• glucose broken down —> 3 pyruvic acid

• pyruvic acid —> lactic acid

• breakdown of glucose = 2 ATP

• breakdown of glycogen = 3 ATP

• carbs are only ones stored anaerobically

at lower intensity exercise, what is the activity of LDH and PDH in glycolysis?

• LDH = low activity

• PDH = activated

at higher intensity exercise, what is the activity of LDH and PDH in glycolysis?

• LDH = metabolizing lactate

• PDH = max activity

explain the advantages and disadvantages of lactic acid

adv.

high rate of ATP production

can get ATP anaerobically

disadv.

lactic acid, lowers pH, causes fatigue, does not completely oxidize glucose

factors affecting muscle lactate concentration (4)

• O2 availability

• enzyme activity

• muscle fiber type

• muscle lactate transporters

why is increased lactic acid a problem?

decrease in pH = lower enzyme activity and X-bridge cycling (stop of contractions)

lactate threshold

the exercise intensity where blood lactate [] jumps a ton

blood pH and lactate [] are

inversely related

tests that measure capacity of the short-term energy system

anaerobic power/capacity testing

wingate cycle test

peak power

max anaerobic power during first 5 seconds

mean power

average power over entire 30-s test

percent fatigue

decline in power output over course of test

better lactate threshold =

better ability to work at high lacate []

explain an overview of oxidative metabolism

• breakdown of carbs or fats to CO2 and H2O

• relies on O2 to breakdown fuels for energy

• occurs in mitchondria

• can yield a LOT of ATP like 37ish

• used during endurance

3 essential steps in aerobic metabolism include

1. formation of acetyl CoA

2. oxidation (krebs cycle)

3. formation of ATP (ETC)

fat is used as ATP aerobically through…

beta oxidation

triglycerides —> beta oxidation __> acetyl CoA

calorimetry

measuring a person’s energy expenditure

direct calorimetry equates to

heat

indirect calorimetry relates to

O2 and CO2

bomb calorimetry

measures the energy value from food

carbs = 4cal/g

fat = 9cal/g

protein = 4cal/g

what is indirect calorimetry used for? (measuring VO2)

• access exercise intensity

• estimate energy expenditure

• determine (RER) type of fuels used

a limitation for indirect calorimetry is

• can only use to estimate EE at steady state

• we assume ATP is from aerobic rxns, cannot use it with anaerobic systems

temp and volume are

directly related

volume and pressure are

inversely related

RER stands for

respiratory exchange ratio

RER =

VCO2/VO2 (CO2 produced/O2 consumed)

what can RER tell you?

• very accurately determine caloric equivalent of a given amount of oxygen consumption

• type of macronutrient fuel being used

• exercise intensity

intensity and CHO usage increases, RER

increases

duration and fat usage increases, RER

decreases

what is the significance of the VO2 Max?

sets the functional range of aerobic capacity

how do we measure VO2?

difference between O2 inspired and amount O2 expired

VO2 = ViO2 - VeO2

how do we know when a VO2 is reliable?

1. must use at least 50% of total muscle mass

2. exercise needs to be continuous and rhythmical

3. test independent of skill or motivation

4. measurements made under standard conditions

5. VO2 needs to plateau

criteria for VO2 max

1. plateau in VO2

2. reach age predicted HR max (220-age)

3. high blood lactate (8 x resting value)

4. RER > 1.1

5. voluntary exhaustion

what is the fick equation for VO2 max? define the variables

VO2 = Q x (a-vO2diff)

Q = cardiac output max (heart rate x stroke volume) CENTRAL FACTOR

a-vO2diff = difference in arterial and venous oxygen content PERIPHERAL FACTOR

factors that affect VO2 Max

• heredity

• mode of exercise

• body size and comp

• sex

• age

• endurance training

what’s wrong about assumptions with testing submaximal exercise for VO2 max?

can lead to 10-20% error

adaptive thermogenesis

the adjustment in energy expenditure related to environmental changes

explain the relationship between exercise duration and intensity, O2 deficit, and recovery

longer duration and intensity = longer recovery and higher O2 deficit

shorter duration and intensity = faster recovery and less O2 deficit

O2 deficit =

(steady state VO2 (L/min) x min of exercise) - actual amount of oxygen consumed

O2 deficit increases, anaerobic systems…

increase

those trained more…

reach steady state quicker, therefore have a smaller O2 deficit