Exam 1 Flashcards
What is exercise physiology
The study of exercise on the function of tissues, organs, and systems, in terms of how the body responds to acute stress and chronic stress (training)
What are the 6 components of effective physiological testing
The variables should be relevant to the sport, tests should be sport-specific, equipment must be calibrated, testing procedures should be carefully controlled, tests should be repeated at regular intervals, and tests should be valid and reliable
What are common confounding variables in exercise research
Temperature, humidity, noise level, food intake, and sleep
When would you use a One-way ANOVA compared to a factorial ANOVA
One-way is for 3 or more independent gropus and one independent variable where factorial is for 4+ independent groups and 2+ independent variables
What is direct calorimetry
A measurement of heat production as an indication of metabolic rate
What are the 2 pros of direct calorimetry
It’s accurate over time and good for resting metabolic measurements (daily activities)
What are 4 cons of direct calorimetry
It’s expensive and slow (bc/have to wait for heat to be expelled), the equipment adds extra heat, sweat creates errors in measurements (bc/evaporates and cools), and it’s not practical or accurate for exercise
What is indirect calorimetry
A measurement of oxygen consumption and carbon dioxide production as an indication of metabolic rate
What are the pros and cons of indirect calorimetry
Older methods of analysis are accurate but slow and newer methods are faster but expensive
What is VO2
Volume of oxygen consumed per minute
What is VCO2
Volume of carbon dioxide produed per minute
What is one way to determine if someone is at their VO2 max
A plateau in their oxygen uptake
What is a MET
A metabolic equivalent for resting metabolic rate (1 MET = 3.5 ml/kg/min)
What is exercise efficiency
The most work for the least input (ATP, kilocalories, or fuel used)
What 3 factors influence exercise efficiency
Exercise work rate (inverses), speed of movement (typically optimum speed and deviations reduce efficiency), and muscle fiber type (slow/type 1 fibers have more efficiency)
What is running economy
Oxygen cost of running at a given speed (because cannot calculate efficiency of horizontal running)
–> Better running economy is lower relative VO2 at same speed
What is the x axis in steady state exercise
Time
What is the x axis in graded exercise
Intensity
For someone to reach steady state what do they need
They have to do oxidative phosphorylation at a submaximal rate
What are 5 examples of stresses
High temperature, low cellular energy levels, abnormal pH, alterations in cell calcium, and protein damage by free radicals
What are heat shock proteins
Also called “stress proteins”, they repair damaged/unfolded proteins that resulted from high heat
Can passive heating (e.g. a hot bath) lead to an increase in Hsps
Yes because of the increase in heat, it can induce the production of Hsps and increase energy expenditure, but passive heating can’t fully replace exercise
What is metabolism
The sum of all chemical reactions that occur in the body
What is bioenergetics
Converting foodstuffs (fats, proteins, carbohydrates) into usable energy for cell work
What is the energy yield of macronutrients
1g Carbs = 4 kcals
1g Protein = 4 kcals
1g Fat = 9.5 kcals
How can muscle glycogen be measured
Via muscle biopsy or wavelengths of light
What is the main enzyme in glycogenolysis
Glycogen physphorylase
What is the main enzyme in gluconeogesis
Glycogen synthase
What is the lactate shuttle
Lactate produced in one tissue builds up and can be transported to another
What is the cori cycle
Lactate can be converted to glucose in the liver (happens more during rest than exercise bc/during exercise blood is diverted away from the liver)
About how much ATP is stored in the body
100 grams (enough for ~10 seconds)
What are the 3 ATP synthesis pathways
ATP-PC system, glycolysis (non-oxidative), and oxidative phosphorylation
What is the ATP-PC systhem
An anaerobic process that occurs from 1-5 seconds of maximal exercise (good for fast, explosive movements) that produces 1 mol of phosphocreatine (PC) / 1 mol ATP
What is phosphocreatine (PC)
It cannot be used for cellular work but it can be used to reassemble ATP
What is the best way to take ccreatine monohydrate supplements to increase ATP synthesis
To start with a 20-25 g/day loading dose then move to a 2-5 g/day maintenance dose
What are the side effects of creatine supplements
GI distress, nausea, and cramping but no long-term studies done
What is the ATP yield of glycolysis
2 ATP if starting with glucose or 3 ATP if starting with glycogen per 1 mol substrate
When does glycolysis occur
Intense exercise longer than 5-15 seconds
What are the pros of glycolysis
Allows muscles to contract with limited O2 and permits shorter term, higher-intensity exercise (up to 45 secs) than oxidative metabolism can maintain
What are 4 cons of glycolysis
Low ATP yield, inefficient use of substrate, lack of O2 converts pyruvic acid to lactic acid, and lactic acid (H+) impairs glycoslysis and muscle contraction
What is the ATP yield of oxidative phosphorylation
32 ATP if starting with glucose, 33 ATP if starting with glycogen, and 100+ ATP per FFA
What is the duration of oxidative phosphorylation
Indefinite (something else will give out first)
How many ATP do NADH and FADH2 make
NADH makes 2.5 ATP, FADH2 makes 1.5 ATP
What does the rate of FFA entry into muscle depend on
The concentration gradient because of passive diffusion
Why is oxidation of fat slower than glucose oxidation
Because carrier proteins are needed to transport fats and they need to be broken down
What is the up-front expenditure of beta-oxidation
2 ATP to chop the fatty acid into 2-carbon acetyl-CoA
What is the equation for total ATP from different FFAs
Total ATP = (n-1) *14 + 10 - 2
n = #C/2
What is the respiratory exchange ratio
The volume of CO2 produced / The volume of O2 consumed when at steady state
Why can RER be > 1
Because CO2 can be produced by the bicarbonate buffering system
Is metabolism at rest anaerobic or aerobic
Aerobic
What are blood lactate levels at rest
Low (<1.0 mmol/L)
What is resting O2 consumption
0.25 L/min or 3.5 ml/kg/min (1 MET)
During rest-to-exercise transition, what happens
Initial uptake in anaerobic ATP production pathways lie ATP-PC systm and non-oxidative glycolysis
What is the oxygen defecit
Lag in oxygen uptake at the beginning of exercise when O2 demand is greater than O2 consumed
About how long does it take someone to reach steady state after starting exercise
1-4 minutes
How is ATP requirement met after steady state is reached
Aerobic ATP production
How does endurance training effect the O2 deficit
It lowers the deficit (same VO2 at lower [ADP]) and results in less lactate and H+ formation and less PC depletion
What is the relationship between exercise duration and substrate utilization
Prolonged exercise leads to an increase in fat utilization compared to carbohydrate utilization
Why does increased duration of exercise lead to more fat utilization
Due to an increased rate of lipolysis, catalyzed by lipases stimulated by rising blood levels of epinephrine
What is the effect of training on muscle fuel source
Endurance trained athletes will use more fat and less carbs than less-fit athletes during prolonged exercise at the same intensity
What are 2 physiological factors influencing VO2 max
Maximum ability of cardiorespiratory system to deliver oxygen to the muscle and ability of muscles to use oxygen and produce ATP aerobically (e.g. how many mitochondria he muscles have)
How does exercise intensity impact fuel selection
Low-intensity exercise prioritizes fat utilization while high-intensity exercise prioritizes carb utilization
What 2 factors impact the “crossover” concept
Recruitment of fast muscle fibers that are better equipped to metabolize carbs than fats, and increasing blood levels of epinephrine to stimulate glycogenolysis
Why does epinephrine promote carb utilization rather than fat utilization during high-intensity exercise
Despite promoting lypolysis, not many fats will be broken down or utilized because there will be little blood flow to adipocytes during exercise
How does traning impact the crossover concept
Endurance training leads to increased utilization f fat and sparing of plasma glucose and muscle glycogen
What is the lactate threshold
The work rate at which blood lactic acid rises systematically during graded exercise
What are 4 potential mechanisms to explain the lactate threshold
Low muscle oxygen (*not well accepted), accelerated glycolysis, recruitment of fast-twitch fibers, and reduced removal rate of lactate removal
What are 4 practical uses of the lactate threshold
Prediction of endurance performance in a 10k run, marker of training intensity, selecting training heart rate based on the threshold, and traning near/just below the threshold to shift the threshold to the right
What is McArdle’s Disease
A genetic error that causes glycogen phosphorylse to not be made which prevents the breakdown of muscle glycogen (and thus prevents lactate production)
How do patients with McArdle’s disease utilize and oxidize fat
They utilize more fat as a fuel during submaximal exercise but they can’t oxidize more fat because “fats burn in the flame of carbs”
Why might carbs be needed to oxidize fats
Because fats are oxidized in the krebs cycle, and reduced rates of glycolysis lead to reduced krebs cycle intermediates and thus less fat metabolization
What is the FATmax
The highest rate of fat oxidation reached just before lactate threshold
What is Excess post-exercise oxygen consumption (EPOC)
Oxygen consumed is greater than Oxygen demand because uptake remains high into recovery –> “Rapid” and “slow” portions
How are O2 deficit and EPOC related
A greater O2 deficit leads to a greater EPOC (so greater EPOC after high intensity exercise)
What are 2 factors contributing to excess rapid EPOC
Resynthesis of PC in muscle and restoration of muscle and blood oxygen stores
What are 4 factors contributing to excess slow EPOC
Lactate conversion to glucose, elevated body temp, post-exercise elevation of HR and breathing, and elevated hormones
What are 3 effects of growth hormone
Stimulating protein synthesis and growth, increasing gluconeogenesis in the liver, and blocking glucose entry into adipose cells to favor fat mobilization
Is growth hormone anabolic or catabolic
Anabolic (promotes, but not required for hypertrophy/muscle growth)
How do exercise intensity and duration impact growth hormone secretion
Growth hormone secretion increases with both exercise intensity and duration
How do exercise intensity and duration impact catecholamine secretion
Secretion of both epinephrine and norepinephrine increase with exercise duration and intensity
How does training impact catecholamine secretion
At the same workload, training resultes in decreased NE/E secretion
What are 4 actions of cortisol secretion
Mobolizing tissue amino acids, mobolizing FFAs, stimulating gluconeogenesis, and blocking entry of glucose into tissue
How does exercise intensity influence cortisol secretion
Increased intensity increases cortisol secretion
What does glucagon do
It spares glucose by increases lipolysis in adipose tissue and increases gluconeogenesis and glycogenolysis in the liver
How does exercise duration influence glucagon secretion
In untrained individuals, secretion increases with duration but the increase is much smaller in trained individuals because the exercise is easier
What does insulin do
Increases glucose uptake into most cells by translocating GLUT-4 transporters to the surface, increases glycogen synthesis and decreasing glycogenolysis in the liver and muscle, and decreases gluconeogenesis in the liver
How do catecholamines influence glucagon/insulin secretion
They stimulate glucagon secretion via beta-adrenergic receptors of alpha pancreatic cells and inhibit insulin secretion via alpha-2-adrenergic receptors of beta pancreatic cells
How is the secretion of insulin influeced by both exercise duration and intensity
Secretion of insulin decreases with both exercise duration and intensity
How does exercise intensity impact glucose release from the liver
It reduces the release of glucose from the liver because increased intensity diverts blood away from the liver
How do muscle cells take up more glucose during exercise if insulin secretion is reduced
Exercise promotes the translocation of GLUT-4 transporters to the surface, even in the absence of insulin
Also increased blood flow to the muscles makes insulin seem more concentrated there
What is the effect of lactic acid on FFA mobilization
Decrease in FFA mobilization may be due to elevated [H+] which inhibits HSL and high levels of lactic acid which promote the resynthesis of triglycerides
Other than lactic acid, what factors could lead to decreaes in FFA mobilization
Inadequate blood flow to adipose tissue and insufficient albumin to transport FFA in plasma
What are the 4 effects of decreased plasma volume during exercise
Increased hydrostatic pressure/tissue osmotic pressue, decreased plasma water content via sweating, increased heart strain, and decreased blood pressure
Why does blood flow still decrease despite release of hormones to increase blood volume during exercise
Because there isn’t any blood going to the kidneys to be filtered so there is nothing to reabsorb, etc.
What are examples of sterile inflammation during exercise
Muscle tears or foot-strike hemolysis (pressure during running ruptures RBCs)
What is low grade chronic inflammation caused by
Inactivity, obesity, and aging
What is high grade chronic inflammation caused by
Certain cancers and rheumatoid arthritis
What effect does moderate exercise have on the immune system
40-60% VO2 max boosts innate and adaptive immune system transiently for ~3 hours
What effect does high-intensity/long-duration exercise have on the immune system
It decreases the amount of B, T, and NK cells, as well as decreases their function, decreases nasal nuetrophil phagocytosis, decreases nasal and salivary IgA, and increases pro- and anti-inflammatory cytokines
What does the J-shaped curve show
Exercise can have both positive and negative effects on the risk of developing upper respiratory tract infections (URTIs)
What other factors may influence the J-shaped curve
Travel, pathogen exposure, sleep, mental stress, diet, and sex
What may cause the “open window” for infection
High cortisol levels or lack of sleep, mental stress, exposure to pathogens, etc.
Does exercising in different temperatures increase one’s risk for infection
No, while exercising in hot environments increases cortisol levels, it is not enough to impart the immune system
Exercising in cold temps doesn’t even impact cortisol levels
Does exercising at high altitude increase one’s risk for infection
Yes, it increases the levels of cortisol and risk of URTI in the field (lab results differ)
Should you exercise when you have a cold
If you have above the neck symptoms you can exercise with reduced intensity/duration, but you shouldn’t exercise with symptoms below the neck, fever, fatigue, or wild spread muscle aches
