Term
| define exercise, exercise physiology, acute vs chronic exercise |
|
Definition
Exercise- task dependent change in homeostasis caused by
increasing the degree of muscle contraction above rest
Exercise physiology- the study of the body’s responses to acute and
chronic bouts of exercise
Exercise Types
Acute: single bout of exercise
immediate, concerted, and simultaneous increase in neural,
cardiovascular, pulmonary activity to facilitate muscle activity
Chronic : prolonged exercise program
increased efficiency of physiological systems to facilitate
muscular contraction |
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|
Term
| define aerobic vs anaerobic exercise. define muscular endurance vs cardiorespiratory endurance |
|
Definition
Aerobic: O2 requirement – taxes cardiorespiratory systems
and muscle capacity to generate ATP
Anaerobic: taxes non-O2 dependent muscular energy
systems
Endurance
Muscular - ability of a muscle fiber to sustain the intensity of
exercise
Cardiorespiratory - ability to sustain prolonged rhythmic
exercise, related to the body as a whole |
|
|
Term
| define work, power, and law of mass action |
|
Definition
Work- Total energy expended
Force x distance (Joules, Nm, kCal)
Taking body weight (force) and moving it one mile (distance)
Power- The rate at which work is performed
Indicative of exercise intensity: higher power output=more intense
Work/time (Joules/s, Watts)
Law of Mass Action
At equilibrium, there is no net conversion from product to reactant or
vice versa
If the equilibrium is disturbed, a net reaction will result
The direction is driven by the amounts or product or reactant
Example: bicarbonate buffering system
H + HCO3H2CO3H2O +CO2 |
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Term
| how is power generated for exercise, and what are the time frames? |
|
Definition
ATP-PCr system-immediate
Glycolytic system-short term
Oxidative system-long term |
|
|
Term
| what are some properties of the ATP-PCr system? |
|
Definition
Phosphate (Pi) from phosphocreatine (PCr) is donated to ADP to produce
ATP in cytoplasm
1 ATP produced per 1 PCr
No oxygen required (anaerobic)
Rapid reproduction of ATP (0-3 s)
High intensity/explosive exercise lasting no more then 15s
e.g., 100 meter sprint, deadlift |
|
|
Term
| what are some properties of the glycolytic system? |
|
Definition
Use of glycogen or glucose to produce
ATP in the cytoplasm
Glycogen stored in liver or muscle, Glucose
from blood
Anaerobic
Produces ATP and 2 pyruvate molecules
Pyruvate becomes lactic acid in cytoplasm
2 ATP per glucose, 3 ATP per glycogen
High intensity exercise (e.g. 400 m
sprint)
lasting 1-2 minutes
Limiting factor - maybe lactic acid, maybe carbohydrate stores, but more likely ? |
|
|
Term
|
Definition
its part of the citric acid cycle. Formed from reduction of pyruvate in
recycling of NAD or when insufficient
O2
is available for pyruvate to enter
TCA cycle.
If NADH + H+ can’t pass H+ to
mitochondria, H+ is passed to pyruvate
to form lactate |
|
|
Term
| What are some reasons that carbs are the preferred fuel for aerobic metabolism? |
|
Definition
ccurs more rapidly than energy generation from FFA
Produces more ATP/L of O2consumed
primes the system for fat metabolism |
|
|
Term
|
Definition
Provides more ATP per substrate molecule, but slowest form of
energy production and requires more 02 |
|
|
Term
| how do we estimate the % of each substrate used for energy? |
|
Definition
Respiratory Exchange Ratio (RER):
CO2 Produced/O2 Consumed
VCO2/VO2
These values are dependent on the
substrate being utilized for energy
production:
FFA: RER of FFA =.7
CHO: RER of carbs=1.0
limitations: |
|
|
Term
| what substrates are used during exercise? |
|
Definition
all 3, but differs depending on intensity.
45% maximum workload – primarily fat usage
70% maximum sustainable workload - predominantly carbohydrates
Associated changes in RER occur with increases in exercise intensity |
|
|
Term
| Should people who want to lose weight therefore work at only lower intensities?? |
|
Definition
| NO! the total energy expenditures are much lower for low intensity. its all about total calories burned. |
|
|
Term
| What is VO2, and why should we measure it? |
|
Definition
measure of net O2
consumption of the whole
body
capacity for O2
transport from
cardiorespiratory system to
muscle-delivery and extraction
capacity to produce ATP
aerobically in muscle
It is proportional to intensity or
power output |
|
|
Term
| what is absolute vs relative VO2? |
|
Definition
Absolute VO2: L/min
Relative VO2: ml/kg/min
example: a runner who weighs 70 kg and a sedentary individual who weighs 140 kg may have the same absolute VO2, but the relative VO2 of the runner will be much higher. |
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|
Term
| What are some typical values of VO2? |
|
Definition
3-4 L/min (6-7L/min)
Typical 40ml/kg/min
(90ml/kg/min)
Good predictor of aerobic
endurance/ fitness
Use of Indirect Calorimetry |
|
|
Term
| What are some criteria of VO2 max? |
|
Definition
Respiratory exchange ratio
(VCO2/VO2) 1.15 (it gets this high because of bicarbonate blowoff becaust of lactic acid production)
HR in last stage 10 beats•min
-1
of
HRmax
Plateau in VO2
with increasing work
rate
RPE=20 (range: 6-20) |
|
|
Term
| what is VO2max for VO2 peak? |
|
Definition
| you never really utilize 100% of your muscle capacity, so we really never know what VO2 peak actually is. we can try to estimate it from VO2 Max |
|
|
Term
|
Definition
| rating of perceived exertion. the BORG scale goes from 6-20 because it roughly correlates to heart rate. |
|
|
Term
| how does VO2 max change with aging and training? |
|
Definition
AGING:
VO2 max decreases by 1% every year after
25-30 yrs
TRAINING:
2-6 months of training
Protocol - 3x per week, 30 min, at 75% of VO2 peak
Increases in sedentary pre-train VO
2max by almost 20% |
|
|
Term
| what are some limitations to VO2 Max |
|
Definition
- Sedentary/conditioned -O2 utilization
Endurance athletes -O2 delivery |
|
|
Term
| what is the concept of lactate threshold? |
|
Definition
actate Threshold: Exercise intensity at which blood lactate accumulates above resting levels
production of lactic acid (LA) (through anaerobic metabolism) exceeds
clearance
Onset of Blood Lactate Accumulation (OBLA)-concentration > 4 mM
LA = H+ + lactate
May not limit short duration contraction, but is associated with decreased ability to sustain high workloads
Major indicator of the sustained workload (%VO2max) attained |
|
|
Term
| what happens with chronic aerobic training? |
|
Definition
Decreased stress on anaerobic systems because aerobic capacity is
improved
increases the % VO2max you can work and speed you can run |
|
|
Term
| what is a sustainable % of VO2 Max |
|
Definition
| Higher %Vo2 max can be maintained at a high level by elite athletes e.g. (85% vs. 45%) for 1 hr |
|
|
Term
| what is economy, with regards to exercise? |
|
Definition
Greater economy reflected in
lower oxygen cost at same
workload
less energy is expended to
maintain a given speed
Many individuals may change
running economy without
changing VO2max
Two runners with similar VO
2max may have difference running
performance times |
|
|
Term
| what are the factors that affect performance? |
|
Definition
VO2Max/VO2Peak
% VO2Max
Economy
Motivation
*Consider this in both athletic performance and in ADLs
in people who are impaired |
|
|
Term
|
Definition
Phosphocreatine (CP) and anaerobic glycolysis: early to
accommodate for slow rise in blood flow to working muscle
Aerobic: Long duration at reduced effort.
cellular energy use exceeds oxygen uptake |
|
|
Term
| what is excess post exercise oxygen consumption? |
|
Definition
Also termed “debt” – assuming
oxygen is “borrowed” from tissue
Exercise ↓’s myoglobin saturation
levels, but amount consumed in
recovery for replenishment ≠
excess VO2
Fast and slow components |
|
|
Term
| what is the fast component of EPOC? |
|
Definition
20% of EPOC: Lasts about 30 seconds
Restore myoglobin O2
stores/ maybe blood stores??
Restore PCr (Cr + AT P→PCr + ADP)
Na+/K
+
AT Pa s e(restore Na
+/K
+
balance in nerves/muscles)
Other reactions restoring ionic and metabolite balances? (some
are ATP driven) |
|
|
Term
| what is the slow component of EPOC? |
|
Definition
Slow component of EPOC
80% of EPOC: About 15 minutes
Sustain increased level of contraction of heart and
respiratory muscles
Clearing excess blood lactate
Gluconeogenesis and glycogen synthesis at liver and
muscle are ATP driven reactions
Historically was major component, now known to be a
minor contribution to EPOC (muscle conversion to
pyruvate)
↑Metabolic Rate
↑Body Temperature (↑Enzyme Activity - Q10 effect)
↑Circulating Hormones |
|
|
Term
| how does sympathetic activity help regulate exercise? |
|
Definition
Reticulospinal drive –
serotonin/norepinephrine based
Peripheral modulatory effects –
norepinephrine-epinephrine based
Resets chemo-/baroreceptors to allow
increase pressure, increased perfusion
Redistribution of blood flow
Bronchodilation/increased ventilation for improved gas exchange
Drives catabolism/fuel mobilization |
|
|
Term
| adaptations to chronic training |
|
Definition
you decrease your activity of the sympathetic system, so lower heart rate.
Less “drive” to
center/less effort
required for same
workload
Higher maximal work
can be achieved |
|
|
Term
| how do we increase VO2 during exercise? |
|
Definition
increase delivery by increasing cardiac output (heart rate x stroke volume),
and we increase mitochondrial activity in an acute bout, and increase # of mitochondria in a chronic scenario. |
|
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Term
| Fick equation of oxygen consumption |
|
Definition
| VO2= cardiac output x a-v O2 |
|
|
Term
| CV response to aerobic exercise-heart rate |
|
Definition
HR increases proportionately
until maximum is reached
Mechanism:
Initial increase up to 90-100 bpm –
decrease parasympathetic drive
Later increases up to max (~200) -increased sympathetic responses
People with heart transplants, HR
does not increase initially (loss of
parasympathetic input)
Post-training effects
at a given workload, HR will be
lower
Increase vagal output during rest?
increase stroke volume
compensates for decreased HR |
|
|
Term
| how does stroke volume respond to aerobic exercise? |
|
Definition
Increases until 40-50% of max intensity
because…
Enhanced Diastolic Filling
Venoconstriction
Muscle pump/thoracoabdominal pumps
Increased gradient from aorta to rt. atrium
Increased Systolic Ejection
Increased pre-load causes increased ejection
(Frank-Starling Law)
Increase contractility with sympathetic
responses |
|
|
Term
| Why does the stroke volume vs VO2 curve flatten? |
|
Definition
| maybe pericardial sac limits it. Also you have used up your stretch. maximum stretch level reached. also, you are pumping faster , so you don't have as much time to refill. maximum speed of filling has been reached. |
|
|
Term
| what are some chronic changes to stroke volume with training? |
|
Definition
Chronic changes with
Training
SV can increase up to 60%
above resting values
Increased filling time with
decreased heart rate at a
given workload
Increased ventricular
chamber diameter
"volume overload"; not muscle
hypertrophy, except in resistance
training - "pressure overload" |
|
|
Term
| overall changes to cardiac output with training? |
|
Definition
Increases to 20-40 L/min to match
need for O2
varies with body size and
conditioning level
Training effects
increases at max to meet O
2need
Changes primarily due to SV changes
(HR max doesn’t change) |
|
|
Term
| how is blood flow changed or redistributed during exercise? |
|
Definition
Redistribution of blood flow
At rest, 15% of blood flow to inactive muscle
Maximal exercise - 85% blood flow to active muscle
Vasodilation to active muscle, constriction to inactive tissue
Increased delivery
Occurs with increased cardiac output
Functions
Increase O
2
delivery
Clear metabolite and CO2
build up
Restraints
battle of blood flow to skin (to release heat) and muscle, especially in high temp.
Flow to brain remains the same |
|
|
Term
| what are some hemodynamic changes with exercise? |
|
Definition
Systolic- increases w/ intensity (Increased CO, particularly SV)
Diastolic-no change or decrease (Decreased TPR)
MAP remains almost constant
Increased CO but decreased peripheral resistance (vasodilation)
Training effects: BP will decrease at rest (usually with high intensity - maybe), and at given work rate |
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|
Term
| why is the blood pressure higher in arms than legs? |
|
Definition
smaller muscle groups = more resistance because of less capillaries.
you want to do leg evxercises in people with high BP, it will drop their BP a bit maybe |
|
|
Term
Humoral chemoreceptors
Central chemoreceptors
Located in the medulla
PCO2and H
+
concentration in
cerebrospinal fluid
Peripheral chemoreceptors
Aortic and carotid bodies
PO2, PCO
2, H+, an d K+
in blood |
|
Definition
|
|
Term
| what is supraspinal vs segmental input? |
|
Definition
| segmental is where skeletal muscle automatically activates respiratory activity when they move. supraspinal is brainstem control |
|
|
Term
| how is pulmonary ventilation regulated? |
|
Definition
Pulmonary ventilation
Minute ventilation (VE
)= tidal
volume (TV)* frequency (f
B
)
maximum rate: 100-200 L/min -depending on lung size and
conditioning level; Increases w/
work
At low intensity, there is an
increase in both f
Band TV
At high intensity, increase in
frequency only (TV plateaus) |
|
|
Term
| what are the mechanisms underlying pulmonary ventilation? |
|
Definition
feedforward control - stimulation of respiratory brainstem centers via
descending signals from supra-brainstem structures simultaneously
activating working muscles
feedback control - reflex activation of respiratory centers via increased
sensory input from muscle and joint mechanoreceptors; also from lung
receptors
elevation of body temperature
increased stimulation of respiratory centers via increased circulating
catecholamines (NE, Epi)
blood PO2, P
CO2, and CO
2
-generated H+
do not vary significantly with increasing exercise intensity in trained individuals (up
to ~75% VO2max
)
May contribute in untrained individuals |
|
|
Term
| what is ventilatory breakpoint? |
|
Definition
With increasing workload < 50% VO2
max,
ventilation increases linearly
With workload > 55-70% VO2
max, ventilation
increases disproportionately (V
E/VO
2
slope
increases)
May be due to lactic acid accumulation and
“blow-off”
Increased work increases glycolytic ATP generation
Lactic acid+ NaHCO
3= Na-lactate + H2O + CO2
Increased blood CO
2
stimulates chemoreceptors
in the medulla that will cause hyperventilation |
|
|
Term
| what is the mechanism of ventilatory breakpoint? |
|
Definition
McArdle’s patients cannot
anaerobically metabolize glucose
Still generate a ventilatory breakpoint
multifactorial; Mazzeo and Marshall
1989 – possibly EPInephrine |
|
|
Term
| what are some respiratory limitations to performance? |
|
Definition
Respiratory muscles account for 11% of O2 consumption and 15% CO2 production
Ventilation limiting exercise
can limit only some
elite athletes, rarely
Likely limiting in individuals with restrictive or obstructive diseases |
|
|
Term
Pulmonary diffusion dependent
primarily on pressure gradients |
|
Definition
Diffusion at alveoli
Blood - high CO2, low O2
Alveoli – high O2, low CO2
Diffusion at tissues
Blood – high O2, low CO2
Tissue – high CO2, low O2
Gases diffuse down
concentration gradients |
|
|
Term
| what factors affect hemoglobin binding to oxygen? |
|
Definition
98.5% transported by hemoglobin
1.5% dissolved in plasma
Near complete saturation at 80 mmHg
O2
or above
At lower partial pressures, the
hemoglobin releases oxygen
shift of the curve to the right with
decrease in pH (increased H+), increased CO2 decreased temperature
2,3 DPG |
|
|
Term
Chronic Adaptations to Aerobic
Exercise |
|
Definition
ncrease in ventilation at maximum
VO2
Very little changes in respiratory
muscle capacity
Usually not a limiting factor
Large increase in oxygen extraction
during exercise
Increased Type I, Type IIa fibers
Increased mitochondria
Increased myoglobin
Increased capillarization
Increased fat and CHO stores |
|
|
Term
| aerobic training results in what? |
|
Definition
↑oxidative capacity
↑reliance on aerobic
metabolism
↓lactate production at same
workload
Remember:
lactate threshold indicates switch
from aerobic to anaerobic energy
production |
|
|
Term
| how is fuel mobilization regulated during exercise? |
|
Definition
Fuel metabolism and mobilization
increases during exercise via
endocrine and autonomic effects
Increased sympathetic activity
Increases with exercise intensity -spillover
Adrenal medulla releases NE (20%)
and Epi (80%) into bloodstream
Metabolic effects
increased glycogenolysis
increased FFA release
increased glucagon, decreased insulin
secretion
Increased reliance
on fats at lower
intensity
Increased reliance
on CHO at higher
intensity |
|
|
Term
| what is the role of insulin and glucagon in exercise? |
|
Definition
Pancreas increases glucagon, decreases insulin
secretion
insulin not needed for exercise-induced glucose
uptake
Due to:
increased sympathetic activity at pancreas
decreased blood glucose levels
Effects of increased glucagon secretion
increased glycogenolysis (at liver and muscle)
increased gluconeogenesis (at liver)
increased lipolysis (at adipose tissue)
Effects of decreased insulin secretion
decreased glycogen synthesis
decreased glycerol production (increased lipolysis) |
|
|
Term
| does body weight or surface area to volume ratio increase or decrease BMR? what hormones increase BMR? |
|
Definition
| it increases BMR. thyroxine and epinephrine increase BMR as well. |
|
|
Term
| what are the 4 mechanisms of heat exchange? |
|
Definition
Radiation – loss of heat in the form of infrared rays
Conduction – transfer of heat by direct contact
Convection – transfer of heat to the surrounding air
Evaporation – heat loss due to the evaporation of water from
the lungs, mouth mucosa, and skin (insensible heat loss) |
|
|
Term
| what is the major agent of heath transfer within the body? |
|
Definition
|
|
Term
| what is the role of the hypothalamus in thermoregulation? |
|
Definition
The main thermoregulation
center is the preoptic/anterior
region of the hypothalamus
Receives input from
thermoreceptors in the skin and
core
Responds by initiating appropriate
heat-loss and heat-promoting
activities |
|
|
Term
| what are some heath promoting mechanisms in the body? |
|
Definition
Low external temperature or low
temperature of circulating blood
activates heat-promoting centers of
the hypothalamus to cause:
Vasoconstriction of cutaneous blood
vessels
Increased metabolic rate - shivering
Enhanced thyroxine release (maybe –
elevated in deep sea divers)
Activation of erector pili |
|
|
Term
| what are the major heat loss mechanisms in the body? |
|
Definition
When ↑temperature, activation
of heat-loss center:
Vasodilation of cutaneous blood
vessels
Enhanced sweating
Filtration of plasma into eccrine
sweat glands
Resorption through tubular
epithelium – hypotonic solution
Voluntary measures for both
heat loss and heat promotion |
|
|
Term
| What happens when you exercise in hot environments? |
|
Definition
you have to redistribute blood flow to the skin, so therefore you must decrease blood flow to working muscle.
Increase sweat gland recruitment – gradual
fluid loss
Gradual fluid loss
Increase sweating rate in warm/hot
environments
Reduced tubular resorption
Increase electrolyte loss
decrease cardiac output. decrease stroke volume. increase heart rate. decreased central venous pressure (it is going to the periphery). Skin blood flow elevates, |
|
|
Term
| what are some physiological responses to heath accumulation? |
|
Definition
decrease cardiac output. decrease stroke volume. increase heart rate. decreased central venous pressure (it is going to the periphery). Skin blood flow elevates,
surface blood flow is increased at
expense to other tissues
increase EPI release
increased anaerobic glycolysis
decrease blood volume
decrease efficiency (SV)
increase heart rate (“CV drift”)
increase fatigue |
|
|
Term
| why is lactate so much higher in the blood when you exercise in the heat? |
|
Definition
| decreased blood flow to the muscles (because it has to go to the periphery) shifts the muscle metabolism to anaerobic reactions and produces lactate |
|
|
Term
| how does fluid balance affect exercise? |
|
Definition
ehydration impairs endurance performance,
minimal effect on power and speed events
blood volume will skin blood flow and
heat dissipation
thirst mechanism doesn’t keep up with
dehydration
need for water replacement > than
electrolyte replacement
fluid intake during exercise will:
minimize dehydration
minimize rise in body temperature
reduce CV stress
[CHO] > 6-8% slows absorption from gut |
|
|
Term
| what happens when you train in hot environments, how does your body adapt? |
|
Definition
increase body fluids/blood volume (w/in 3-5 d)
More blood available to muscles
increase rate of sweating (may take up to 10 d)
decrease electrolyte loss
increase heat tolerance
Decreased heart rate, increased stroke volume |
|
|
Term
|
Definition
Normal heat loss processes ineffective; elevated body temperatures depress the
hypothalamus
positive-feedback mechanism, increasingbody temperature and metabolic rate
termed heat stroke, can be fatal if not corrected |
|
|
Term
|
Definition
eat-associated collapse after vigorous exercise, evidenced by elevated body
temperature, mental confusion, and fainting
Causes
dehydration and low blood pressure
Heat-loss mechanisms are fully functional
Can progress to heat stroke if the body is not cooled and rehydrated |
|
|
Term
| what happens during a fever? |
|
Definition
Controlled hyperthermia, secondary to immune response or
CNS injury
Release of endogenous pyrogens that act on the hypothalamus
release of prostaglandins
reset the hypothalamic thermostat
Elevated temperatures increase metabolic rate of immune
reaction |
|
|
Term
| what happens when you exercise at altitude? |
|
Definition
Environmental stresses of
altitude include:
Reduced barometric pressure
Slightly reduced partial pressure of
oxygen (Po2
)
O2-Hb dissociation curve -small change saturation until
~3,000 m
At higher elevations, decrease in
Po
2,
impairs oxygen loading
(steep portion of O2-Hb curve) |
|
|
Term
| how does your body adjust to altitude? |
|
Definition
Immediate
Hyperventilation - triggered by increased
respiratory drive
Increased cardiac output-rest and
submax
Long-term
Acid-base adjustment - loss of alveolar
CO2
due to hyperventilation, increases
the blood’s pH
Increase in red blood cell production
Increased capillary and mitochondrial
densities in skeletal muscle |
|
|
Term
| how is athletic performance affected after training in high altitude? |
|
Definition
eturn to sea level, little if any
increase in endurance
performance is found
Live high, train low
Athletes live at 2500 m, trained at
1250 m > performance 5000 m
increases vs. athletes lived, trained at
2500 m or both at sea level
Exercise intensity improved at
normoxia PLUS daily adaptations to
high altitude/reduced O2
Hypoxic tents or nitrogen chamber
(insufficient data)
Reduced exercise intensity at
high altitude
Reduced blood buffering capacity
Hyperventilation at altitude
reduces CO2
Reduced CO2 causes
adaptation of reduced HCO3-buffering capacity |
|
|
Term
|
Definition
Blood doping -RBC and blood volume
Autologous – reinfusion of packed RBC (4-6 weeks)
Heterologous – reduced use (immune rxn/blood-borne
disease)
2-13% improvement in performance |
|
|
Term
| how would you increase O2 delivery while cheating? |
|
Definition
EPO - stimulates RBC
production
Risks of increasing blood
viscosity
Detection within first few
days of recombinant EPO
use – not a major barrier |
|
|
