Measuring energy expenditure(to know how much energy. A person is expending)
the direct method is called - Direct calorimeter
• measures the body heat production , to calculate energy expenditure
advantages and disadvantages of - Direct calorimeter
The only real advantage is that it measure heat directly, but they have several disadvantages for exercise physiology
• it cannot follow rapid changes in energy expenditure
• although useful for measuring resting metabolism, but most of us are going to be interested in exercise metabolism
• exercise equipment may give off its own heat
• not all heat is liberated from the body. Some of it is actually stored and increases the body temperature
• sweating affects the measurement and the constant use in the calculation of heat produced
this method is based on the fact that ?
spirometry is an indirect measure b/c?
The technique is referred to as Spirometry
• in order for oxygen consumed to reflect energy metabolism accurate energy production must be almost completely what?
• is an indirect calorimeter method for estimating heat production in which expired air is measured and analyzed for the amount of oxygen consumed and carbon dioxide produced
• this method is based on the fact that oxygen consumption at rest or during submaximal exercise is directly proportional to the aerobic production of ATP (does not include the anaerobic portion) and when expressed as calories is equal to the heat produced by the body as measured by direct calorimeter
• however since heat is not measure directly spirometry is an indirect measure
(once you know a person oxygen consumption with that you can determine their energy expenditure. How much work have they done also)
The technique is referred to as Spirometry
• in order for oxygen consumed to reflect energy metabolism accurate energy production must be almost completely oxidative (that's why we're only going to get that aerobic portion oxidative not that anaerobic portion which is more glycolitic)
• if a large portion of energy is being produced and aerobically, respiratory gas measurement will not reflect all metabolic processes
• therefore, this technique is limited to steady - state activities lasting about 60 seconds or longer. (Maybe 2 min.)
respiratory gas exchange is determined through measurements of ?
• respiratory gas exchange is determined through measurements of the volume of oxygen and carbon dioxide that enters and leaves the lungs during a given period of time
• because the body have only limited oxygen stored the amount taken up at the lungs accurately reflects the body use of oxygen
close versus open spirometry
• in a close system the subject breathes from a sealed container filled with gas of a designated composition (often it's 99.0% o2)
• an open circuit spirometry or the subject inhales room or outdoor air from his or her surroundings and exhale into the same surroundings (just the atmospheric air)
• a sample of the expired air is analyzed for oxygen and carbon dioxide content
The respiratory exchange ratio is?
to estimate the amount of energy use by the body, it is necessary to know the type of what?
as a result the amount of oxygen used during metabolism depends on the type of?
the ratio varies due to ?
• to estimate the amount of energy use by the body, it is necessary to know the type of food substrate being oxidize.
• The carbon and oxygen content of glucose, free fatty acids and amino acids differ dramatically
• as a result, the amount of oxygen used during metabolism depends on the type of fuel being oxidize
• remember indirect, calorimeter measures the amount of carbon dioxide released, and oxygen consumed
• the ratio between these two values is termed the respiratory exchange ratio
• the ratio of the volume of carbon dioxide released (Vco2) divided by the volume of oxygen consumed(Vo2) on a total body level
the respiratory exchange ratio
• is the carbon dioxide produced divided by the oxygen consumed
the ratio varies due to difference in the chemical composition in substrate.
In general the amount of oxygen needed to completely oxidize a molecule of, carbohydrates or fat is proportional to the amount of carbon in that fule; for example, glucose (C6H1206) contains six carbon atoms.
During glucose combustion, six molecules of oxygen are used to produce six carbon dioxide molecule. Six H2O molecules, and 30 - 32 ATP molecules
(when we oxidize the glucose what we gonna get is six molecules of carbon dioxide, six waters and 30 to 30 ATPs)
(so really what we're going to see is where the oxygen and the carbon dioxide produced from that oxygen is really1 to 1 for carbohydrates)
• so by evaluated how much CO2 is released compared with the amount of O2 consumed. We find that the RER(respiratory exchange ratio) is 1.0
• RER - VC02/Co2= 6co2/6o2=1.0 (six carbohydrate divided by six oxygen equals one)
• as mentioned, the RER value varies with the type of fuels being used for energy.
• Free fatty acids have considerable more carbon and hydrogen, but they have less oxygen. Than glucose.
• Therefore the combustion of a fat molecule requires significantly more oxygen than combustion of a carbohydrate molecule
• although fat provides more energy than carbohydrates, more oxygen is needed to oxidize that fat than carbohydrate
• this means that the RER value for fat is substantially lower than for carbohydrate
• for palmite acid
• RER = VCO 2/VCO2 = 16co2/23o2=0.70
Once the RER value is determined from the calculated respiratory gas volume. The value can be compared with a table to determine the food mixture being oxidize(table 4.1)
if, for example, the RER value is 1.0 then the cells are using only glucose or glycogen and each liter of oxygen consumed would generate 5.05kcal (kilocalorie per liter)(if you know the RER, you can go to the table and figure out the kcal expenditure )
the oxidation of only fat would yield 4.69kcal L of o2 consumed
Individuals do not often use only one fuel. Thus, the classic values are rarely seen
the RER value at rest is usually 0.78 -0.80
(which is indicating 33 carbohydrates and 67 of fat, but we are using mostly fat, but some carbohydrates. We have to exercise because it's not utilizing enough calories because fat stores a lot of calories)
Estimation of caloric expenditure.
Estimation of caloric expenditure.
• From the known values of the volume of oxygen per liter per minute( Vo2L) and the RER, it is possible to compute the kilocalorie expenditure
assume that an individual had an RER of 0.90 during exercise that used to
2 .15 Liters of oxygen ( o2) per minute
the caloric equivalent for an RER of .90 is 4.92kcal per L of 02 so that the calculation becomes
and if we don't have that table; you can plug in what number?
so the calculation becomes
• 2.15 L of oxygen x the Minute x 4.92 kcal - L02= 10.57kcal per Minuit
if you know the oxygen consumed during any activity, but do not know the RER, which is very likely because you did not measured the ratio(you did and measured directly oxygen uptake) . You can estimate the caloric value of that activity by multiplying five kilocalories per liter of oxygen. (There is a relationship for every liter of oxygen, 5 kcal are expended)
before we use the RER from that table. But if we don't have that table; you can plug in five
you can estimate five kilocalories are expended for every liter of oxygen consumed
remembered that this caloric cost is an estimate of the aerobic portion only
What is the energy expenditure someone who consumed on average 1.50 L of oxygen per minute during a 30 min. activity?
• 1.50lx5x30min equals= 225
The metabolic equivalent (Mets)
• Oxygen uptake and kilocalories commonly expressed the differences in exercise intensity. As an alternative a convenient way to express exercise intensity would be to classify physical effort as multiples of the resting energy expenditure, with a unit less measure.
• To this end scientists have developed the concept of Mets.
• One met represents an adults average seated resting oxygen consumption or energy expenditure, about 3.5 mL of oxygen per minute
• This is relative description of oxygen in liters that is an absolute measure of oxygen
• we talked about when a person weight changes were going to get different numbers(mets) and we get to compare people large people. Small people based on their weight and oxygen consumption
Using this frame of reference a 2 met activity requires twice the resting metabolism, a three met intensity level would require three times as much energy expenditure or oxygen consumption at rest, and so on
the met provides a convenient way to rate exercise intensity with respect to a resting baseline
when you get into metabolical calculations)(don't need to know)
• they'll be asking you about the energy expenditure on a net and on a gross level meeting that a gross level will be including the resting level and exercise where a net level is only, referring to the exercise, not the resting
A giving mass of lean body tissue
• requires the same amount of oxygen at rest and at any given work rate, irrespective of gender, race, age and level of fitness. The resting relative oxygen consumption is always assumed to be 3.5 mL of oxygen per kilogram per minute.(1000 mL go into a liter)
• Various expressions of V02 are used depending on the purpose for its measurement.
• The absolute rate of Vo2 is typically expressed by the units liter per minute. In this form Vo2 can be converted to the overall rate of energy expenditure (the kcal). Everything has to go back into liters in order to get to kilocalories
• (if you know the pounds in order to get to get the kg you divided by 2.2)
The consumption of 1 liter of oxygen results
whatis the vo2 for colleg man and women ?
• in the liberation of approximately five Kilocalories of energy(and that vary slightly depending on the RER)
• the relative VO2 is commonly used to compare oxygen consumption of individuals who vary in size. Because Vo2 Max is also used as an index of cardiopulmonary fitness, a higher value is indicative of greater aerobic power
(so when people talk about their Vo2 Max at a certain level. What that is saying. The higher that number generally, the higher the fitness level of that individual)
the average Vo2 college men and women, are 38 to 42 for woman and 44 to 50 for men
to calculate met levels
• divide the amount of oxygen utilized in milliliters by 3.5
• hence, if an individual . Expends 29 mL per kilogram of oxygen on an activity the met level is equal to 8.3 Mets
• I just took 29 and divided that by 3.5 and I get 8.3
• What is the met equivalent to
• 8.7 mL per kilogram per minute
equals 2.5 you divide the 8.7 by 3.5 and that equals 2.5
What is the absolute oxygen consumption equivalent to 10 Mets for a 155 pound male.?
10 x 3.5 =35 milliliters per kilogram per minute
(155 divided by 2.2=70.5) 35x 70.5= 2467.5 milliliters per minute or 2.47 L per minute. If I divide the milliliters by one thousand then I get the liters
If I have 2.47 L per minute. I could also determine kilocalories
• To convert from Mets to Vo2 in absolute terms
• first multiply the met value by 3.5
• to convert Mets to Vo2 in relative terms, then multiply the product by body weight in kilograms
to convert from mets to kilocalories per minute
• We take the Total met x 3.5 mL per kilogram per minute x the body weight equals
• total number of milliliters per kilogram per minute
• to convert the liters x number by 5 kcal and divide by 1000
Kilocalories per minute equals Mets =x 3.5 x bw x 5 kilocalories
divided by a 1000
Calculate the kilocalorie per minute. For an individual who is working at a met level of 8.3 Mets and weight is 68
8.3 Mets x 3.5 mL per kilogram per minute x 68weight x 5 kilocalories , liter of oxygen= 1975.4ml per kilogram per minute divided by 1000= 9.877 kilocalories per minute
Energy costs of various activities
The amount of energy expended for different activities varies with ?.
• The amount of energy expended for different activities varies with the intensity and type of exercise
• despite subtle difference in economy, the average energy cost of many activities have been determined, usually through monitoring of oxygen consumption during the activity to determine and average oxygen uptake per minute kilocalories of energy use per minute. Then can be calculated from this value if you know the Mets go to kilocalories ViceVersa kilocalories go to Mets
• the approximate kilocalorie for an activity can be found in exercise physiology book some most give you the kilocalorie per activity and some books give you the met level, so you can try to get an exercise that would meet the goals and the needs of your client
factors that affect the energy cost. Specifically is the intensity and duration
Limitations of indirect calometry
• we can accurately, assume that oxygen being remove from the air we breathe is in proportion to its cellular uptake (that's the premise)
• carbon dioxide exchange, however, is less constant. Body carbon dioxide pools are quite large and can be altered simply by deep breathing, or by performing highly intense exercise
• (so we can't make that same assumption that the carbon dioxide is not equal to what, where, exhaling is the same amount of that. We're producing through metabolic methods that we have other ways that we can increase our carbon dioxide in our system again, just by deep breathing and so on)
under these conditions, the amount of carbon dioxide released in the lungs may not represent that being produced in the tissues, so calculations of carbohydrate and fat use based on gas MEASUREMENTS appear to be valid only during rest or steady-state exercise
(rest is obviously very easily and steady-state is just usually a condition where things level off and that usually occurs when you increase an intensity of an activity, and until it takes a couple of minutes for the heart rate to steady out and your blood pressure to steady out. And someone other things to study out. So it takes a couple of minutes and then doing that particular level. Your heart rate is going to stay the same, and everything pretty much is going to stay the same and that is what is referring to as a steady-state)
(so basically, your book is saying that these Spirometry or in direct calorimetry or oxygen up take methods are dependent on us understanding when we do it we can't have somebody changing the intensity each time and going up and down, and so on and being anaerobic and so on).
protein is another factor because
because proteins is not completely oxidize in the body this makes it impossible to calculate the body proteins use (so that is another limitation using the method and that is we cannot oxidize the nitrogen
if exercise is hard and involves anaerobic metabolism causing an increase in acidity. a decrease in our pH and co committen rise in non metabolic CO2 release, then the respiratory exchange ratio no longer represents just fuel utilization (so they are some other things that are going to be involved, causing a difference in the pH and acidity and those kinds of things that have nothing to do with fuel utilization. So that's a limitation, especially what are doing anaerobic work at a high intensity)
Values during exercise, especially as an individual approaches maximal effort usually exceeds one (they're talking about the RER). In this case, the assumption is that the fuel source is, carbohydrate and the excess CO2 is a result of anaerobic metabolism. Conversely, after initial increase during recovery CO2 is retained, causing low values
(the most important part is, there are limitations to this particular method and again limitations really are around not being able to determine the protein usage, not being able to determine the anaerobic portion or contribution and so on. It's limited to a steady-state aerobic activity)
rate of Energy expenditure at rest and during exercise
estimate of energy expenditure at rest and during exercise are often based on
at which the body expends energy is termed•
measurements of whole body oxygen consumption (v02) , and it's caloric equivalent
At rest an average person consumes about 0.3 liters of oxygen consumption per minute.
This equals what?
This equals 18 L of oxygen per hour or 432 L oxygen per day
At rest an average person consumes about ?
This equals what?
at rest the body usually burns a mixture of carbohydrates and fats. And RER value of .80 is fairly common (that's an indication of carbohydrates and fats being use.
The caloric equivalent of an RER value of .80. If you look at that table, you would see its 4.80 kilocalorie per liter of oxygen consumed (from table 4.1)
using these common values, we can calculate this individual caloric expenditure which is?
At rest an average person consumes about 0.3 liters of oxygen consumption per minute. This equals 18 L of oxygen per hour or 432 L oxygen per day
(kilocalories per day )kilocalories/day equal liters of oxygen consumed per day
(kilocalories per day )kilocalories/day equal liters of oxygen consumed per day
x kilocalories use per liter of oxygen
= 432 L of oxygen per dayx(estimated RER) 4.80 kcal/liters of oxygen
= 2074 kcal/day
basically, most of us need to taken approximately well. It differs from men and women., Then it differs from how physically active you are. But in general most people require 2074 kcal per day
this value closely agrees with the average resting energy expenditure expected for a 70 kg (154 pound) man. Of course, it does not include the extra energy needed for normal daily activity (so that is just basically not being very physical. So those are the minimum number of calorie needs. However it will be different between man and woman also older and younger people)
difference between the basal metabolic rate and the metabolic rate
• the BMR is the rate of energy expenditure for and individual at rest in a supine position, measured immediately after at least eight hours of sleep and at least 12 hours of fasting. This value reflects the minimum amount of energy required to carry on the essential physiological function
• the resting metabolic rate does not require the individual to sleep over night in A hospital or research laboratory.
Values are essentially identical, and they range from 1200 to 2400 kcal per day, but the average total metabolic rate of an individual engaged in normal daily activity ranges from 1800 to 3000 kcal
(so this is just a little bit difference in definition for these particular terms. Again, this is very strictly regulated to determine the basal metabolic rate compared to the resting metabolic rate. Again, much more strict for the measurement)
factors affecting both
• the more fat free mass. The higher the BMR
• the more body surface area. The higher the BMR (you see that that in children a lot)
• BMR gradually decreases with increasing age
• BMR increases with increasing body temperature. (It's great to have a fever your burning calories all over the place:)
• the more stress. The higher the BMR
• the higher the level of thyroxine and epinephrine, the higher the BMR
• (so these are the factors)
metabolical rate during submaximal exercise
exercise increases the energy requirement well in access of what?
Metabolism increases is direct proportion to what?
metabolism increases in a direct figure reaching a steady-state value within what? and it ?
there is a linear response to approximately 70% of a person's VO2 Max, which increases in power output.
From recent studies vo2 response at higher rates of work does not what?
at power output above the lactate threshold, The oxygen consumption continues to what?
This increase has been called what?
Which is a alteration in? and require a ?
v02 drift defined as?
exercise increases the energy requirement well in access of the resting metabolic rate. Metabolism increases is direct proportion to the increase in exercise intensity reaching a steady-state value for a 1 to 2 min. varies depending on age
metabolism increases in a direct figure reaching a steady-state value within 1 to 2 min.
(so you see on that particular page, you'll see a line going up until the person reaches a steady-state basically after a couple minutes)
there is a linear response to approximately 70% of a person's VO2 Max, which increases in power output.
From recent studies vo2 response at higher rates of work does not follow the steady-state response
it appears that at power output above the lactate threshold, The oxygen consumption continues to increase beyond the typical 1 to 2 min.
(lactate is being produce all along during activity and then we reach a point and the intensity where we have more is being produced and not being removed. Basically, so it reaches a threshold). (So you're not going to see that nice steady-state that you see with below the lactate threshold.)
This increase has been called the slow component of oxygen uptake kinetics, the mechanism for the slow component is an alteration in muscle fibers recruitment patterns with the recruitment of more type 2 fibers which are less efficient. They require a higher VO2 to achieve the same power output
(so we are talking about that high intensity workout, when we get up there. We start to recruit more of those fast twitch fibers to help us out and where not again going to be able to see that linear relationship that steady-state relationship)
a similar but unrelated phenomena is referred to as v02 drift defined as
• a slow increase in v02 during prologue, submaximal, constant power output exercise.
• Unlike the slow component, v02 drift is observed at power output well below lactate threshold and the magnitude of the increase in the vo2 drift is much less.
• And oxygen drift, the oxygen consumption increases despite the fact that oxygen requirement of activity have not changed. Vo2 drift is attributable
(cause no one knows)
to an increase in ventilation and effects of an increase circulated, catecholamines, our stress hormones epinephrine and norepinephrine
(mostly understand the steady-state and doing a particular activity and that's at some point what happens is what we all experience. It's hard to maintain our performance in doing that activity and so now the body is going to be trying to look for help is going to be recruiting if we doing an endurance activity where we have mostly slow twitch muscle fibers now we are starting to need more of the fast twitch fibers to bring them in may be where at such a high level of the activity that we were unable to use fats, usually that occurs at that lactate threshold meaning that when regular people get to that lactate threshold, you usually can see it when you start gasping for air and start breathing heavy because what's happening is there using more carbohydrates glycolic pathways more carbon dioxide are being produce all of these things are beginning to happen and when you get this increase in lactate, lactate is going to probably inhibit that mobilization of fat to be used.)
(Now those that really affect athletes' as much as regular people? No, because athletes will train at higher level of their VO2 and when their training at higher levels of their Max vo2. There actually increasing that lactate threshold, so where it might be 70% for you. It might be 90% for and athlete, which allows them to spare their glycogen to be able utilize fats more efficiently to provide energy than regular people. Because when you get to a some of these level you will be able to maintain that intensity and you could gonna have to slow down or stop.)
Maximum capacity for aerobic exercise
• the highest amount of oxygen an individual can take in ,transport and utilize to produce ATP aerobically while breathing air during heavy exercise is called
• maximal oxygen consumption (vo2 max)_
• (. Meaning that this is the highest, highest level that a person is able to utilize o oxygen at)
• (so If we had a ramp kind of a situation where someone was on a treadmill and we had the treadmill set at a certain speed and elevation and they are starting off and they have a work load, and we see it going up, and then it will go to a steady-state and then we increase the workload again and what we gonna see is that it's going to go up and then steady out again. And then we turn the treadmill again and we'll see it: up and, then it's gonna steady-state out again. Now you turn it up and what happens is, well, each time it goes up oxygen consumption goes up as well. So when we get at this level, you turn it up and crank it up, and our oxygen consumption doesn't change that is considered your Vo2 max, at that level is your maximum capacity to be able to utilize oxygen to produce energy at that level. That's the reason why we don't use heart rate to determine a person's Vo2)
why is heart rate, not a good indicator of measuring your vo2 max
• the heart rate goes up because that is indicative of the blood that is being circulated by the heart. So for a while there is a linear relationship and then at some point oxygen in heart rate are going to defer at the higher ends so heart rate would not be a good indicator of measuring your vo2 Max
• the most accurate way to measure your vo2 is spirometry)
vo2 Max is =
to cardiac output(heart rate (the frequency at which the heart beat)s x stroke volume(the amount of blood injected with each beat)x av02 difference(arterial venous oxygen difference)
(and that is actually looking at the difference between the oxygen that is going in and oxygen and carbon dioxide going out). The difference is what we used to make energy so that's what you're vo2 is.
This is your delivery system, which consists of your heart and all of your blood vessels that go to that tissue specifically now to our muscles and this is a utilization system the ability of your muscles to extract the oxygen from the blood)
The vo2 max is the ability to utilize oxygen on a cellular level
• there is an upper limit of a person's ability to increase, they cannot go any further
• good indicator of cardiorespiratory endurance and aerobic fitness
• can differ according to sex body size age and is greatly influenced by the level of aerobic training
several physiological criteria can be used to determine if the vo2 max test is actually a maximal test(these are some other ways to determine was it the Max has?)
• A lactate value greater than 8 mv per liter
• a heart rate plus or minus 12 beats per minute of your predicted maximal heart rate
• an RER of 1 or 1.1 primarily dependent on the age of the subject, cause that's going to indicate that they work really, really hard, that they was only using carbohydrates
• and a plateau. In oxygen consumption(where they would no be able to increase their oxygen consumption anymore)
Anaerobic effort and maximal capacity for anaerobic exercise
the most common methods for estimating anaerobic effort involves?
• the examination of either the excess post exercise oxygen consumption, or what we call Epoc
• or the lactate threshold-that is when the person starts to increase more carbohydrates and more glyolitic pathway,
post exercise oxygen consumption
When aerobic exercise begins, the oxygen transport system does what?
although the body oxygen requirements are not fully met you still need oxygen. Even though supply and demand are not equated or equal
• because oxygen needs and oxygen supply defer during that transaction from rest to exercise, the body incurs an oxygen deficit which is defined as
• the matching of energy requirement during exercise with oxygen delivery is not perfect.
• When aerobic exercise begins, the oxygen transport system does not immediately supply the needed quantity of oxygen to the active muscles
(we start to exercise we need oxygen very quickly. There always seems to be a lag time. For getting oxygen to the muscle)
• oxygen consumption require several minutes to reach the required steady-state level at which the aerobic process are fully functional
(as we saw before the steady-state you know that the amount of oxygen needed is equal to the amount that is being supplied at that steady-state )
• although the body oxygen requirements lags you still need oxygen. Even though supply and demand are not equated or equal
because oxygen needs and oxygen supply defer during that transaction from rest to exercise, the body incurs an
• is calculated as the difference between oxygen required for and given exercise intensity and the actual oxygen consumption
• despite the insufficient oxygen delivery at the onset of the exercise, the active muscles are able to generate the ATP needed through anaerobic pathways
(We said in the past that it takes a couple of minutes for our aerobic system to kick in and before it kicks in. We are able to utilize our immediate system ATP PCt and we are able to use the Glycolit pathways to produce energy. And that's in the beginning we ready to go. We don't need oxygen)
Possible factors responsible(why does the oxygen consumption stay up at the end of our activity)?
• because oxygen needs and oxygen supply defer during this transaction from rest to exercise, the body incurs an oxygen deficit
• until we reach our steady-state of oxygen consumption and here you have the end of exercise, but you'll still see that our oxygen consumption is still up and then over a period of time. It's going to come down
so during recovery oxygen consumption demand does not immediately decrease instead oxygen consumption remains elevated temporarily.
• This consumption, which exceeds that usual required when at rest, its that , oxygen consumption beyond our resting level
• the more common term today is exccess post exercise oxygen consumption. epoc
during recovery oxygen demand is not immediately decreases instead oxygen consumption remains high.
Possible factors responsible(why does the oxygen consumption stay up at the end of our activity)? However, it's transient and the does not last for very long
however, after doing a physical activity. We do have this increase in oxygen consumption that stays up for a while and there is more calories being spent
• People usually breathe heavier at the end of an activity
• However, it's transient and it does not last for very long
• however, the higher intensity of the activity, especially resistance training and endurance training. It's not the type of activity.
It's the intensity of the activity and what we're going to see is that it goes up because we have a lot of housekeeping in our bodies to take care of when you just engage in this intense activity your poping out hormones, they trying to take substrates and break them down, and depleting your glycogen, your body temperature goes up because you have all these heat going there is a lot of things going on at the end of that activity to get you back to homeostasis. Overall, there is a big cleanup that has to happen. That's why there is a increase of oxygen at the end of an activity
Factors invoving epoc factors on why it stay up after exercise
define the lactate process
• restoration of ATP PCR stores oxygen stores removing CO2 that have accumulated in the body tissues.
That's one of the factors
• clearing the lactate does not produced by anaerobic metabolism
•, Brooks says lactate merely supplies fuel to power the recovery process a combustion of lactic acid does not result in extra oxygen consumption
• (he says we going to do something with that lactate at the end through a process called gluconeogenesis, so he saying that, . In reality, the cause of epoc is the general disturbance to homeostasis brought about by exercise
• exercise causes a rise in tissue temperature
• changes in intra-and extracellular ion concentration
• hormone level. Catecholamines are elevated during exercise and affect persistence to recovery your epinephrine and norepinephrine, and they will last into the recovery and that has to be dissipated
• and an athlete will dissipate that, then a regular Joe
• and another tests to determine whether you have good physical fitness is to have you do a physical activity very hard and then to measure your recovery heart rate. How quickly your heart rate can come back down (the Harvard step test)
what contributions to fatigue?
• many investigators considered the lactate threshold to be a good indicator of an athlete's potential for endurance exercise.
The lactate threshold is defined as the point at which blood lactate begins to accumulate substantially above the resting concentrations during exercise of increase intensity
• the lactate threshold has been thought to reflect the interaction of the aerobic and anaerobic system
(your going along and then all of a sudden it starts to get a little bit harder to do is your still at the same level on the treadmill now may be the anaerobic system will have to kick in the provide that energy)
some researchers have suggested that the lactate threshold represents a significant shift towards the anaerobic glycolysis, which forms lactate.
(And again, we know that this is not a bad guy, so we have more lactate, and again it's not being cleared quickly as it needs to be and if we have to much lactate, we have too much hydrogen ions. Maybe they'll be buffered, but they will be some that are not going to be buffered and remaining in the blood it is really whats going to have to make you slowdown or stop the activity)
blood lactate concentration is determined not only by the production of lactate in skeletal muscle or other tissues, but also by the clearance of lactate from the blood by the liver, skeletal muscle, cardiac muscle, and other tissues in the body
the lactate threshold is best defined as the point in time during exercise of increasing intensity when the rate of lactate production exceeds the rate of lactate clearance or removal
• the lactate threshold is usually expressed as the percentage of maximal oxygen uptake (percentvo2max) at which it occurs.
The ability of exercise at a high intensity without accumulating lactate is beneficial to the athlete because lactate and hydrogen ions accumulation contributions to fatigue
• blood lactate levels to do not change until about 60%-70% for untrained people
• the ability to perform at higher percentage of v02 probably reflects a higher lactate threshold
• consequently, a threshold of 80 suggests a greater aerobic exercise tolerance, then a threshold of 60%
• there's no athlete or champion that does not suffer in their training
economy of effort
• as people become more skillful at performing and exercise. The energy demands during exercise at a given pace are reduced, in a sense people become more economical so that they don't require as much energy to perform a specific activity
Determining endurance performance success(what do we tell people about their potential)
• you have to have a high oxygen uptake. You have to have that efficiency with the heart Utilization system
• higher lactate threshold when expressed as a percentage of a vo2(that's that painful point)
• higher economy of effort or low vo2 for a given rate of work or efficient
• and a higher percentage of slow twitch muscle fibers because where talk about endurance performance
fatigue and its causes -energy system and fatigue metabolic byproducts and fatigue
• energy system and their byproducts might affect it, such as the hydrogen ions
• energy system and fatigue were talking about the depletion of the PCR(phosphate creatine)
• glycogen depletion, especially activities lasting longer than 30 min.
metabolical byproducts accumulation of lactate and hydrogen
• in short, activity dependent on anaerobic glycolysis produce lactate and hydrogen ions have buffer hydrogen, but bicarbonate keeps cell pH between 6-4 and 7-1
• intracellular pH lower than 6-9 slows glycolysis and ATP production,
• when pH reaches 6.4 levels stop any further glycolysis and results in exhaustion again when to much hydrogen builds up
• neuromuscular fatigue. Another possible factor
• looking at fatigue waste products being produced or running out of to be used for energy and so on, and it might be so neuromuscular fatigue at the neuromuscular junction,
1. Calculate the amount of time a 35-year-old male weighs 70 kg would have to walk in order to expand 200 kcal in a session (use table 4 - 2 to determine the kilocalories per kilogram per minute for walking 3.5 mph)(use the table to get the 5(for walking for the 70kilgram person)
2. Calculate how many minutes the client (above) would need to run at 7.5 mi./h (use table 4 - 2 to determine the kilocalorie per minute for running 7.5 mph )in order to expand 200 kcal
200 ÷70 x .2 (x)
200 = 14x
200 ÷ 14 equals
3. Calculate the kilocalories.min for a female client who weighs 168 pounds and is performing at a seven met activity
168lbs = 76.4kg
5cal=met x ml.kg.min x kg x kcal
Kcal=7met x 3.5ml.kg.min x 70.4kg x 5
4. If an individual respiratory exchange ratio is average at 0.85 during a 30 min. jog, how many calories would he or she use if their average oxygen uptake was 1.5 L/minute (look up the rer)
45L (consume 02)
X4.86 (rer) burned cal