Anaerobic and Aerobic Metabolism

Exercise Physiology Exam #1

ATP-PC system

no O2 consumed

no lactic acid produced

short duration, high intensity exercise

immediately available

more in fast twitch fibers

energy for 2-3s of max effort

lasts 15-30s (replenishes within 30s- 70%)

- also known as alactic anaerobic metabolism

anaerobic glycolysis

no O2 consumed

lactic acid produced

short duration, high-intensity exercise

produced ATP quickly

kicks in when phosphagen system depleted

starts 5s after muscle contraction

- also known as the lactic acid system

aerobic oxidation

slow glycolysis, Kreb's cycle, electron transport chain/oxidative phosphorylation

relies on O2

VO2 max

maximal oxygen uptake/consumption during exercise

amount of oxygen available for aerobic production of ATP

time-energy system continuum

maximal maintainable intensity (100% VO2 max @ 10 minutes, 95% VO2 max at 30 minutes, 85% VO2 max at 60 minutes, 80% VO2 max at 120 minutes). Supramaximal for <5 minutes

how long you are able to maintain an intensity

lactic acid

byproduct of anaerobic metabolism

redox potential

A measure of the tendency of a given redox pair to donate or accept electrons.

ratio of NADH + H to NAD+ (facilitates the production of fuel)

MCTs

Monocarboxylate transporters

act in lactate shuttles to move lactate down concentration gradients to cross cellular and mitochondrial membranes

regulates intracellular pH by moving lactate and H+

MCT1

high concentration in oxidative skeletal muscle, cardiac muscle, and mitochondrial membranes

removes lactate from the blood and shuttles lactate between/within muscle fibers

greater increase in activity with exercise than MCT4

MCT4

highest concentration in the cell membranes of glycolytic skeletal muscle

Maximal lactate steady state

highest sustainable workload without consistent rise in blood lactate level

production > clearance above this level

lactate threshold

The point during exercise of increasing intensity at which blood lactate begins to accumulate above resting levels, where lactate clearance is no longer able to keep up with lactate production.

anaerobic threshold

the exercise intensity above which blood lactate levels rise and minute ventilation increases disproportionately in relation to O2 consumption

basal metabolic rate

minimum level of energy required to sustain the body's vital functions in a waking state (O2 consumption)

75 seconds

after how many seconds is anaerobic and aerobic contribution equal?

creatine

the body can store 90-160 mmol/kg of ___ in dry muscle

creatinine

creatine is broken down into ____ and this reaction is nonreversible

skeletal muscle

95% of creatine is stored in ____ ____

free

30% of the creatine that is stored is stored as ___ creatine

ATP and PC

in the ATP-PC system, what two products can be produced?

equilibrium

under normal resting conditions, pyruvic acid and lactic acid production are in ____

99%

at physiological pH, what percent of lactic acid is immediately broken down into H+ and La-?

fuel

lactic acid increases during anaerobic metabolism to ___ exercise performance

accumulation

this is when production > clearance

clearance

facilitated by oxidation, transamination, gluconeogenesis/glyconeogenesis, and sweat

Production

facilitated by muscle contraction, enzyme activity, muscle fiber type, SNS, and low O2 levels

muscle contraction

when ____ ____ occurs, calcium released from the SR activated glycogen phosphate (enzyme) which facilitates glycogenolysis (fast glycolysis) which produces lactate/lactic acid

LDH (lactate dehydrogenase)

pyruvate + NADH --> lactate + NAD

highest rate of function of all glycolytic enzymes

high pyruvate and NADH = high ___ activity

maintains the redox potential of the cell to keep glycolysis going

PDH (pyruvate dehydrogenase)

pyruvate to acetyl CoA

low; glycolysis

fast glycolytic muscle fibers have ____ mitochondrial density and thus rely on ____

this results in the production of lactic acid/lactate

sympathetic neurohormonal activation

high epi and glucagon --> low insulin --> high glycogen breakdown --> high G6P --> increased rate of glycolysis --> high pyruvic acid production --> high lactic acid/lactate

O2

with insufficient levels, ___ is not available in the mitochondria as the final electron acceptor in the ETS, therefore, the cell must rely on anaerobic glycolysis

out; into

intramuscularly: lactate moves ____ of FOG/FG fibers and ___ SO fibers

cardiac; liver

in the bloodstream, lactate can go to the ____ muscle or the ___

oxidation

what is the primary method of lactate clearance during and after exercise?

power; capacity

the ATP-PC system has more ___ than ____

capacity; power

anaerobic glycolysis has more ___ than ____

oxygen deficit

the difference between the oxygen required during exercise and the oxygen supplied and utilized

occurs at the onset of all activity

EPOC

oxygen consumption during recovery that is above normal resting values

replenishes everything

anaerobic

during the transition from rest to exercise energy is supplied by:

- oxygen transport and utilization

- utilization of oxygen stores in capillary blood and in myoglobin

- the splitting of stored ATP-PC

- ____ glycolysis, with the concomitant production of lactic acid

causes of EPOC

restoration of ATP-PC stores

restoration of oxygen stores

elevated CV-respiratory function

elevated hormonal levels (significant contributor)

ELEVATED BODY TEMP (primary contributor, high metabolic rate- using more O2)

Lactate removal

Energy substrate shift

40-60%

the 1st lactate threshold occurs between what percentages of VO2max?

85-90%

the second lactate threshold occurs between what percentages of VO2max?

muscle lactate

which level increases significantly first?

- muscle lactate

- venous lactate

more reliant on aerobic pathways

with long-term low intensity, lactate production is at a steady rate, why does this occur?

metabolic fatigue

decreased ATP production due to changes in enzymes/membrane transport mechanisms/substrate availability

muscular fatigue

decline in maximal force or power of a muscle as a result of muscle contraction

muscular and neural mechanisms

active recovery

what is the best way to remove lactic acid?

pain

lactic acid activates ___ receptors

no

is there a sex difference of ATP-PC availability and utilization?

greater

there is a ____ accumulation of lactate in males > 16 years old compared to females

more muscle mass

why do males have a greater accumulation of lactate than females > 16 years old?

sex difference

if you normalize lactate levels to muscle mass between male and females there is no ___ ____

shrinks

the sex difference between males and females ____ as we normalize values more in relation to mechanical power and capacity.

same

in children the availability and utilization of ATP-PC is the ____ as adults if we normalize the data

lower

children may have slightly ____ PC stores compared to adults

less

children have ____ lactate accumulation than adults, but there isn't much sex difference between children

clearance rate is similar to adults

higher

in children, lactate thresholds occur at a ____ VO2max

less

children have ____ mechanical power and capacity compared to adults

muscle enzyme theory

this theorizes that kids have lower amounts of PFK and therefore produce less lactate

muscle characteristics theory

this theorizes that children have more FOG fibers than FG fibers and therefore have decreased force production because of that

sexual maturation theory

this theorizes that sex hormones influence metabolism and hence why children have differences from adults

no solid evidence to this

neurohormonal regulation theory

this theorizes that in children activity of the SNS and adrenals is lower and therefore children have less stimulation of anaerobic glycolysis

- children are also better able to do gluconeogenesis in the liver

lower; higher; decreased

older adults have ___ ATP-PC stores at rest

___ amounts of ADP and creatine in muscles

and ___ ATP-PC power by 45% and 35% capacity

lactate

older adults have no difference in resting ____ levels compared to older adults

lower

older adults have ___ lactate accumulation at relative workloads (but higher at absolute workloads because they are working harder)

lower

older adults have ____ maximal lactate levels because the permeability of lactate decreases with age

lactate is not in the blood but in the muscle

one

older adults sometimes may only have ___ lactate threshold that occurs at a higher VO2max

decreased

older adults have ____ mechanical power and capacity

oxygen consumption (VO2)

The amount of oxygen taken up, transported, and used at the cellular level

carbon dioxide produced (VCO2)

The amount of carbon dioxide generated during metabolism

oxygen drift

a situation that occurs in submaximal activity of long duration, or above 70% VO2max, or in hot and humid conditions where the oxygen consumption increases, despite the fact that the oxygen requirement of the activity has not changed.

sweat causes stress

increased catecholamines

increased lactate accumulation

steady state exercise

A state of aerobic exercise in which the intensity remains consistent, as opposed to alternating between higher and lower intensities.

rapid increase of O2 consumption then plateau

light to moderate exercise, submaximally, short-term

> 8 mmol/L

what level does lactate have to reach to be considered a VO2max?

reach age-predicted HR max + or - 12 bpm

what is the VO2max criteria for HR?

1.0 or 1.1

what is the VO2max criteria for RER?

plateau

what must happen to O2 consumption for it to be a true VO2max?

RQ

the ratio of the amount of CO2 produced divided by the amount of oxygen consumed at the cellular level

at rest it should be a non-protein value (protein value is BAD, starvation state and burning muscle mass)

RER

the ratio of the volume of CO2 produced divided by the volume of O2 consumed on a total body state

used during exercise

0.7

what is a fat RQ?

0.81

what is a protein RQ?

1.0

what is a CHO RQ?

high

if an RQ is > 1.0 the person has a ___ CHO metabolism and addition of anaerobic metabolism

protein

if a person has an RQ of 0.82, they are fasting and burning ___ (starvation/muscle wasting) OR utilizing all 3 fuels (normally nourished individual)

caloric cost

O2 consumed (L/min) x caloric equivalent (kcal/LO2)

- use chart to calculate and need RER and O2 consumed

MET

a unit that represents the metabolic equivalent in multiples of resting rate oxygen consumption of any given activity

3.5 mL/kg/min

at rest what is one MET?

walking

for METs when ___ you add onto the resting MET by 0.1 mL/kg/min and for each m/min (speed)

running

for METs when ____ you add 0.2 mL/kg/min for each m/min to the resting MET

incline

for METs when adjusting ____ you add on 1.8 mL/kg/min for each % incline

mechanical efficiency

the percentage of energy input that appears as useful work

gross efficiency

(work output/energy expended) x 100

most useful efficiency measure when values for specific workloads or speeds are needed to ensure adequate replenishment of energy expenditure

most appropriate estimate of whole body efficiency

net efficiency

(work output/energy expended- RMR) x 100

measures amount of work done above resting

delta efficiency

(change in work production / change in energy expenditure) x 100

most accurate efficiency measure for determining the effect of speed or work rate on efficiency

only calculated on a horizontal treadmill (no incline)

economy

____ or oxygen cost has an inverse relationship with efficienct

increase economy = decrease efficiency

no

is there a sex difference in the economy of walking and running in adults?

higher

kids have a ___ oxygen cost than adults

increases

economy ___ as speed increases

factors that cause lower economy in children

high BMR- kids need to consume more O2

large SA/mass ratio- lose heat faster, higher BMR to maintain body temp

immature running mechanics- costs more O2

less efficient ventilation- more air to process (requires more energy)

decreased anaerobic capacity- more reliant on aerobic pathways

factors that cause lower economy in older adults

recruitment of additional MUs

gait instability- extra muscle contraction needed

antagonist cocontraction- both contract and need more O2