"Every morning in Africa, a gazelle wakes up. It knows it must outrun the fastest lion or it will be killed. Every morning in Africa, a lion wakes up. It knows it must run faster than the slowest gazelle, or it will starve. It doesn't matter whether you're a lion or gazelle - when the sun comes up, you'd better be running." (African Proverb/popular running inspirational quote)
I promised a long time ago to put forth a post on Central Governor Theory (CGT), a term thrown around more and more these days, sometimes fairly inaccurately. The basic premise behind CGT is easily explained through the rental car analogy. You pick up your rental car and the speedometer goes up to 120 miles per hour, and assuming you are in something with more horsepower than a Ford Focus, the car could probably be coaxed up to close to such a speed over a long distance. However, no matter how hard you depress the accelerator, the car won’t go above 80 mph. That’s because the rental car company installed a regulator to prevent you from speeding too fast. The car isn’t doing anywhere near its maximal speed, but you aren’t as likely to kill yourself (or total their car) either.
The actual theory is more complicated, however, and has actually been around quite a while but came back into vogue with an interesting experiment recently published by Samuele Marcora in the European Journal of Applied Physiology (“The limit to exercise tolerance in humans: mind over muscle?” Marcora SM, Staiano W. Eur J Appl Physiol. 2010 Aug;109(6):1225-6.). Ironically, Marcora did not interpret the results to support CGT proper. Instead he put forth the subtly but importantly different “psychobiological model of exercise tolerance.” However, most folks seem to think the difference was semantic, and have taken his striking results as confirmation of the CGT.
So as M.C. Hammer would instruct us, we must break it down.
The existence of a central governor was first put forth by Archibald Hill in 1924, and refined by Tim Noakes, in a string of papers beginning in 1997 and most notably containing his 2001 paper with Peltonen and Rusko, entitled, “Evidence that a central governor regulates exercise performance during acute hypoxia and hyperoxia.”
Here’s the summary from that article if you wish to “geek out.”
“An enduring hypothesis in exercise physiology holds that a limiting cardiorespiratory function determines maximal exercise performance as a result of specific metabolic changes in the exercising skeletal muscle, socalled peripheral fatigue. The origins of this classical hypothesis can be traced to work undertaken by Nobel Laureate A. V. Hill and his colleagues in London between 1923 and 1925. According to their classical model, peripheral fatigue occurs only after the onset of heart fatigue or failure.
Thus, correctly interpreted, the Hill hypothesis predicts that it is the heart, not the skeletal muscle, that is at risk of anaerobiosis or ischaemia during maximal exercise. To prevent myocardial damage during maximal exercise, Hill proposed the existence of a ‘governor’ in either the heart or brain to limit heart work when myocardial ischaemia developed. Cardiorespiratory function during maximal exercise at different altitudes or at different oxygen fractions of inspired air provides a definitive test for the presence of a governor and its function. If skeletal muscle anaerobiosis is the protected variable then, under conditions in which arterial oxygen content is reduced, maximal exercise should terminate with peak cardiovascular function to ensure maximum delivery of oxygen to the active muscle.
In contrast, if the function of the heart or some other oxygen-sensitive organ
is to be protected, then peak cardiovascular function will be higher during hyperoxia and reduced during hypoxiacompared with normoxia. This paper reviews the evidence that peak cardiovascular function is reduced during maximal exercise in both acute and chronic hypoxia with no evidence for any primary alterations in myocardial function. Since peak skeletal muscle electromyographic activity is also reduced during hypoxia, these data support a model in which a central, neural governor constrains the cardiac output by regulating the mass of skeletal muscle that can be activated during maximal exercise in both acute and chronic hypoxia.”
Pretty straight forward, right?
So basically what they are saying is that this governor in the brain regulates exercise in regard to some neurologically determined safe exertion by the body, particularly the cardiac tissues. That way exercise is controlled so that its intensity cannot threaten the body by causing damage to the heart. The central governor limits exercise by reducing the neural recruitment of muscle fibers, preventing myocardial ischaemia during maximal exertion. This reduced recruitment is what we feel as fatigue. It seems the data support this, because by using altitude to limit oxygen delivery, they showed that peak cardiac output was diminished during max effort without any alterations in normal cardiac function.
Makes sense. Your brain makes sure you don’t exercise till you have a heart attack.
Um…except people die of heart attacks fairly regularly during exercise.
Fair enough. But one can argue the CG is neurologically programmed to protect the normal heart…not the clogged up, weakened model that the average modern adult is toting around. It’s also probably programmed to protect the heart to a certain point, but when the damn thing gets too old and worn then all bets are off (yikes over here). It’s also clear that individuals exist for whom CGT obviously doesn’t apply – they literally race themselves to death.
However, Occam’s razor would suggest that this is a fairly elaborate explanation for a pretty straightforward dilemma – the body protecting itself from exerting itself to death. First of all, how does each individual body know how to neurally calculate its CG? Is it mostly genetic and partially trained like VO2Max? Seems a bit scary…our involuntary responses just guess where the line of cardiac catastrophe is?
Especially when there’s a much simpler way to go about it: if the body FEELS like it’s going to have a heart attack (or other catastrophic physiological breakdown) during maximal exercise it SLOWS DOWN so that said catastrophe doesn’t occur. Otherwise known as rate of perceived exertion (RPE) = 10.
Here’s how Samuele Marcora set about his experiment to prove this. He took 10 professional rugby players – exceptionally fit individuals. He had them do a 5-second maximum voluntary cycling test (MVCT), followed by cycling to exhaustion which took about 10 minutes. Within 1 second of stopping due to exhaustion, they were required to do another 5-second MVCT that they didn’t know was coming.
So here’s the catch. Before hand, this had been widely publicized and made into a contest, with large cash prizes offered to increase motivation. I like the summary on the findings presented by Sweat Science, a great blog on exercise science for normal people.
“Now, if you subscribe to traditional exercise physiology, you’d say that the subjects stopped the test-to-exhaustion when they were no longer physically able to generate enough power to continue. Possible reasons for their failure would include “limited oxygen delivery, metabolic and ionic changes within the active muscles, supraspinal reflex inhibition from muscle afferents sensitive to these changes, and altered cerebral blood flow and metabolism.” But that’s not what Marcora saw. The subjects had to maintain an output of (on average) 242 watts in the test to exhaustion. But as soon as they stopped, one second later, they were able to output (on average) 731 watts in a five-second burst — nearly triple the required power! Clearly the subjects didn’t stop the test because they couldn’t physically produce the needed power.
These results challenge the long-standing assumption that muscle fatigue causes exhaustion during high-intensity aerobic exercise, and suggest that exercise tolerance in highly motivated subjects is ultimately limited by perception of effort.”
Some people argue that this is flawed because when you exercise to exhaustion over a 10 minute period, you are working mainly outside the alactic and gylcolytic energy (anaerobic) systems that you would use for the 5-second burst, and instead are primarily using the aerobic system. At true exhaustion, however, the aerobic system has outstripped the ATP available and the anaerobic system is employed until the 90-120 seconds of glucose/glycogen/ADP/Pi in the muscles is gone (assuming none had been used before which is would have been so in reality this would be even shorter). One second is not enough for the alactic system to recover.
The exception to this would be when glycogen has been depleted to the point where the anaerobic system cannot be employed (another physiological governor since the body holds glycogen in reserve for brain function). Yes – I speak of the true bonk. Unless the subjects had been forced to fast prior to the test, that isn’t going to happen in 10 minutes.
My point is that when they reported exhaustion – if it were true exhaustion – they would have already depleted the ADP/Pi in the muscles that would allow their alactic system to synthesize the ATP necessary for 5 seconds of all-out sprinting. So his conclusion is sound.
Since it’s been proven time and time again that RPE is subjective based on environmental factors, this makes sense for a species developed on the hunt and being hunted. If you have a neurally pre-determined CG that doesn’t allow for you to drive the rental car fast enough to escape the lion, you don’t crash…but you get eaten. Granted, there could be a complex endocrine/neurologic interaction that allows adrenaline inputs to alter the CG’s function. But we already know that if you are outrunning a lion, it doesn’t feel hard – all that limits you is the absolute physiological limits of your neurological recruitment, joints, O2 delivery, and muscular strength. So instead of feeling the pain you just feel too slow – especially when you get caught which you probably will. Ironically, you probably won’t feel that much pain when you get eaten because your adrenaline release and its associated chemical cascade will block your pain receptors….but I digress.
If you are in a footrace with some random guy, competing for a spot in the standings far off the podium and its hot and humid and you have a cramp in your side…your RPE will skyrocket. And for good reason – you are pushing the beginning of the limits of your body, punishing it, and for no biologically necessary reason.
So that’s the distinction between CGT and Psychobiological Model of Exercise Tolerance (PMET), so far as I can tell. CGT is a neurological-cardio regulator preset to prevent cardiac damage from near-maximal exercise, while PMET basically implies that we stop exercising when it gets hard, we go a little farther a little harder when we’re REALLY motivated, but probably don’t realize our full physiological potential until our life is on the line. CGT is one of many regulatory systems that probably kick in when RPE is skewed downward due to environmental factors. Again, some folks seem to be able to convince themselves that their life is on the line when it doesn’t have to be, and keep going when truly redlined. Sometimes they win…sometimes they die.
Like I said, my guess is – and no, I don’t think that an earth sciences degree stands in for one in ex. phys. – that there are a series of regulators in place to guard the body against injury and death. PMET basically takes all of those into account.
• You feel crappy when you run out of sugar…you slow down or stop and find something to eat so that your brain doesn’t run out of fuel and you die
• Your heart is pounding wildly and you are heaving for breath and begin to feel nauseous…so you slow down to puke and let your heart rate come down before causing cardiac damage
• It’s 99 degrees and 100 percent humidity and you begin to feel dizzy forcing you to stop or slow down before you experience heat stroke (or can get to a doc in time to treat it
I think it’s telling that all of these can be trained and acclimated to differing extents in different individuals…but all of them CAN be trained. That means that there IS a buffer that exists between our realized physiological potential and our maximal potential. The fact of the matter is that there are a lot more of us around now who are biologically inferior – either because our bodies don’t sense the impending doom or because our regulators are too active and kick in too quickly – because there are no lions left around to test us and no desperately needed deer to hunt.
I guess the bottom line is that we can learn to push beyond our perceived physical limits, and we can physically accomplish things that we never logically thought possible. But it comes at a risk because there is, in the end, a limit. Push just far enough, and you win the Tour de France (or your AG at your local 5k). Push too far and we’ll see you on the other side.
It all comes down to risk versus reward, just as it did 10,000 years ago. Eventually, I think for most folks, PMET will ultimately tell them when the pain of trying to shave just a few more seconds off the 5k PR just isn’t worth it anymore.
But that might not be until they’ve brought their PR down 10 minutes or more from where they started, each increment gained by making classic physiological gains in oxygen recruitment and distribution, muscle strength, and neurological recruitment, as well as by teaching their minds that each time they push a little harder, life is not at stake.
At least until it is.
Monday, August 30, 2010
Wednesday, June 9, 2010
Metabolic Testing
Do you struggle with your weight? Have trouble achieving an optimal body composition for racing? Have you slashed calories, restricted your diet, and exercised to no avail?
Have you had difficulty performing up to your potential in endurance racing and suspected nutrition as the culprit? Found yourself bonking out when consuming the "recommended" number calories over the course of your marathon or century race?
Unfortunately, the formulas we rely on to determine our baseline and exercise caloric needs are only generic estimates that can be off by hundreds of calories, and which tell us little about the fuel sources that our individual physiologies utilize at various work outputs. Harris-Benedict - the most common estimate of basal metabolic rate - has a margin of error of 1000 calories.
Before going further, lets define some important terms:
Basal (or Resting) Metabolic Rate (BMR or RMR): The number of calories your body consumes to support baseline physiologic function over the course of the day. We think of this as the number of calories you would require to survive if you laid in bed all day staring at the ceiling.
Daily Caloric Expenditure (DCE): The total number of calories you burn each day. This number includes your BMR, any calories you burn through movement and training, and the thermogenic effect of the food you consume (very small percentage of DCE).
Exercise Metabolic Rate: The rate of calories you burn during exercise. This rate varies according to the type and intensity of exercise. As an example, the old "rule of thumb" is that you burn about 100 calories per mile of running. However, upon testing you might find that you burn 4.8 kcal/min at a 12:00 min/mile pace (57.6 cal/mile), 7.6 at a 9:00 min/mile pace (68.4 cal/mile) and 12.4 at a 7:00 min/mile pace (86.8). So if you've been assuming you burn 500 calories on a moderate 5 mile run, you'd be about 158 calories off.
Fuel Recruitment: The mixture of fuels (% fat versus % sugar) that you burn at rest and during exercises of different intensities. I'll discuss this in more detail in a coming post, but the specific mixture that you burn has important ramifications for your approach to eating, training and racing.
All of these natural variations in BMR, EME, and fuel recruitment can contribute to the frustrations that many individuals and athletes experience as they try to optimize their body compositions and fuel for races. However, the good news is that once you learn what YOUR true numbers are you are well positioned to make the changes that will finally be effective in helping you attain success - whether in losing weight, racing to your potential, or both.
But how do you find out what your BMR and EMR really are? Metabolic testing.
Metabolism is the biochemical process of combining nutrients with oxygen to release the energy needed for the body to function. This energy is measured in calories (Kcal). By measuring the volume of oxygen consumed and corbon dioxide produced by an individual both at rest and during exercise, we can determine both amount of energy use and the mixture of fuel sources (fats and sugars) being used.
During exercise testing, it is also possible to determine VO2Max and the threshold at which your body begins to sharply limit the amount of energy it draws from its large resources of free fatty acids, and begins to primarily use your very limited glycogen stores as its energy source. This is what we think of at "threshold" and knowing the pace, HR, or work output with which it is associated is key. Stay just below it, and you can hold that pace for a very long time (from an energy standpoint). Go above it, and your time is quite limited before you run out of fuel if you don't consume AND ABSORB calories (hard for your GI system at such intensities). The result is the dreaded bonk, and in ultra-endurance events, can often also be a DNF.
To perform metabolic testing, we use a mask and tubing system that has sensors connected to assessment equipment that measures the individual's respiratory gases input and output. The data, along with HR, fuel sources, and other biomarkers, are displayed on the computer screeen for the test administrator to observe and monitor. The system looks something like this:
We are very lucky that Seaside Cycle has invested in such a testing unit for use with the elite cyclists and triathletes that it sponsors. Seaside's owner, Scott Bumpus, is also allowing Janda Ricci-Munn and I to offer testing to our clients and the general public.
If you are interested in testing you can email april @ trainingmeetstlc.com or call (978) 729-9048 for more information or to schedule a testing date. You can also visit my website at www.TrainingMeetsTLC.com or Seaside's at www.SeasideCycle.com to learn more.
Have you had difficulty performing up to your potential in endurance racing and suspected nutrition as the culprit? Found yourself bonking out when consuming the "recommended" number calories over the course of your marathon or century race?
Unfortunately, the formulas we rely on to determine our baseline and exercise caloric needs are only generic estimates that can be off by hundreds of calories, and which tell us little about the fuel sources that our individual physiologies utilize at various work outputs. Harris-Benedict - the most common estimate of basal metabolic rate - has a margin of error of 1000 calories.
Before going further, lets define some important terms:
Basal (or Resting) Metabolic Rate (BMR or RMR): The number of calories your body consumes to support baseline physiologic function over the course of the day. We think of this as the number of calories you would require to survive if you laid in bed all day staring at the ceiling.
Daily Caloric Expenditure (DCE): The total number of calories you burn each day. This number includes your BMR, any calories you burn through movement and training, and the thermogenic effect of the food you consume (very small percentage of DCE).
Exercise Metabolic Rate: The rate of calories you burn during exercise. This rate varies according to the type and intensity of exercise. As an example, the old "rule of thumb" is that you burn about 100 calories per mile of running. However, upon testing you might find that you burn 4.8 kcal/min at a 12:00 min/mile pace (57.6 cal/mile), 7.6 at a 9:00 min/mile pace (68.4 cal/mile) and 12.4 at a 7:00 min/mile pace (86.8). So if you've been assuming you burn 500 calories on a moderate 5 mile run, you'd be about 158 calories off.
Fuel Recruitment: The mixture of fuels (% fat versus % sugar) that you burn at rest and during exercises of different intensities. I'll discuss this in more detail in a coming post, but the specific mixture that you burn has important ramifications for your approach to eating, training and racing.
All of these natural variations in BMR, EME, and fuel recruitment can contribute to the frustrations that many individuals and athletes experience as they try to optimize their body compositions and fuel for races. However, the good news is that once you learn what YOUR true numbers are you are well positioned to make the changes that will finally be effective in helping you attain success - whether in losing weight, racing to your potential, or both.
But how do you find out what your BMR and EMR really are? Metabolic testing.
Metabolism is the biochemical process of combining nutrients with oxygen to release the energy needed for the body to function. This energy is measured in calories (Kcal). By measuring the volume of oxygen consumed and corbon dioxide produced by an individual both at rest and during exercise, we can determine both amount of energy use and the mixture of fuel sources (fats and sugars) being used.
During exercise testing, it is also possible to determine VO2Max and the threshold at which your body begins to sharply limit the amount of energy it draws from its large resources of free fatty acids, and begins to primarily use your very limited glycogen stores as its energy source. This is what we think of at "threshold" and knowing the pace, HR, or work output with which it is associated is key. Stay just below it, and you can hold that pace for a very long time (from an energy standpoint). Go above it, and your time is quite limited before you run out of fuel if you don't consume AND ABSORB calories (hard for your GI system at such intensities). The result is the dreaded bonk, and in ultra-endurance events, can often also be a DNF.
To perform metabolic testing, we use a mask and tubing system that has sensors connected to assessment equipment that measures the individual's respiratory gases input and output. The data, along with HR, fuel sources, and other biomarkers, are displayed on the computer screeen for the test administrator to observe and monitor. The system looks something like this:
We are very lucky that Seaside Cycle has invested in such a testing unit for use with the elite cyclists and triathletes that it sponsors. Seaside's owner, Scott Bumpus, is also allowing Janda Ricci-Munn and I to offer testing to our clients and the general public.
If you are interested in testing you can email april @ trainingmeetstlc.com or call (978) 729-9048 for more information or to schedule a testing date. You can also visit my website at www.TrainingMeetsTLC.com or Seaside's at www.SeasideCycle.com to learn more.
Thursday, June 3, 2010
The Importance of RPE
Athletic performance is benefitting from an influx of monitoring and testing technologies that allow athletes and coaches to dial in pacing, fueling, and training stress more precisely than ever. A few of the more common technologies we employ here at TriLife Coaching:
-Heart Rate Monitors
-Power Meters (e.g. PowerTap)
-Metabolic, Threshold and Aerobic Capacity Testing (e.g. New Leaf)
-GPS Pace Monitoring (e.g. Garmin)
-Impedence Body Composition Testing
But for all their value, these technologies do not replace the role of Rate of Perceived Exertion (RPE) in athletes' training and racing.
Defining RPE
The are two main scales for measuring RPE - a 9 point (1-10) and 15 point (6-20) - both developed by Borg. These scales are simple ratings of perceived exertion (RPE) used by many coaches and physiologists to assess an athlete’s level of intensity during training or testing sessions.
The 15-point scale is illustrated below as an example: point 6 would be the equivalent of sitting down doing nothing, 9 would be walking gently, 13 a steady exercising pace and 19/20 the hardest exercise you have ever done.
6
7 - Very, very light
8
9 - Very light
10
11 - Fairly light
12
13 - Moderately hard
14
15 - Hard
16
17 - Very hard
18
19 - Very, very hard
20 - Exhaustion
According to a 2002 study in the Journal of Sports Science, a team of Californian researchers found that, to varying degrees across genders and fitness levels, RPE correlated closely with VO2Max, blood lactate levels, heart rate, and MOST closely to ventilatory levels. The 15 point scale was most accurate, however, there was less confusion for athletes using the 9 point scale.
Measuring RPE
That correlation with ventilation, and the importance of having a clear rating system outside of the laboratory for training and racing, led me to develop the following RPE chart for my athletes to use:
I also like this one:
I encourage athletes to use "half-points" to fine tune the 9-point scale, especially at the high end, to differentiate between high/low end tempo and high/low end VO2Max efforts (e.g. start the two minute repeat at an 8.0 and end at a 8.5). This allows for cardiac drift, mental fatigue, and corresponding RPE drift.
In a laboratory or studio setting it is appropriate to use the 15-point scale and post it in front of the athlete so that they can refer to it and use a wider range of values to pinpoint exertion level.
The Appropriate Evolution of RPE in An Athlete's Development
As the study in the Journal of Sports Science found, "accuracy" of RPE is very much driven by fitness level and experience of an athlete. Someone new to running, for example, might identify themselves as at an RPE 8.0 as soon as then cannot speak in long, complete sentences - what an experienced athlete would correlate with an RPE of 5 -simply because they are not familiar with being out of breath and it is unsettling.
As a coach, however, I think this feedback is important and valid. The "downward" adjustment of RPE in less fit individuals helps prevent injuries and burnout. While that person might not progress as quickly in the short term as if they were working "harder", chances are that their progress will be greater over time because their training will progress more consistently. As their fitness improves and their experience working at more difficult intensities accumulates, their RPE:physiological benchmark (ventilation, HR, lactate, VO2Max %) relationship will become more accurate over time.
The Accuracy of RPE versus Data Collection Technology
Coaches often say that the accuracy of a power meter is less important than the precision. What does that mean? It means that the actual number the meter yields is not as important as making sure that the power meter yields the SAME number under the SAME application of force every time.
The opposite would seem to be true for RPE, however, since we can rarely reproduce all of the variables that go into performance output in an individual athlete, RPE can be the most accurate indicator of performance. Why? Because the human body reacts differently under the same application of stress depending upon many outside variables such as heat, humidity, air quality, mental arousal (adrenaline and other endocrine system releases), menstrual cycle, nutritional intake, training stress load, etc., and that reaction at any given moment can make or break a key training session or race.
Think about it this way: if I am time trialing on the ECV time trial course on a cool, cloudy day, I might record an RPE of 8.0 at my threshold watts of 200 and heart rate (HR) of 185 at minute 15. I had a night of good sleep, a day of good nutrition, and a rest day the day before. However, if I am time trialing at an indoor TT the day after being up with a sick child all night, and where the collective work of the participating athletes has driven the temperature and humidity up, and the available oxygen down, I might record an RPE of 9.5 at 200 watts and a HR of 179 at minute 15.
So RPE is less precise than wattage and HR as an instantaneous indicator of performance (speed). HOWEVER, if this is a 30 minute time trial in both cases, it is likely that I can sustain and even build from an RPE of 8.0 over the latter 15 minutes, but less likely that I can sustain or build from a 9.5. So in the first case it is likely that I can hold or even increase my watts towards the finish, whereas my watts are likely to falter pretty soon in the second scenario (I will spit the bit as they say).
If I pay attention only to wattage/HR as an indicator of correct pacing, then in the second scenario I will blow up, whereas I could have corrected for RPE earlier and finished strongly (albeit not as fast as on a day with ideal circumstances). And in the first scenario, I may very well underperform if I stay within wattage and HR zones, when RPE indicates that I could push harder in the latter stages of the race.
The key is monitoring performance and collecting benchmark data and correlating them to a variety of RPEs under different circumstances. Over time, the athlete will begin to understand more closely the variables that affect real and perceived exertion, and will be able to fine-tune their performances as a result. However, without the ability to honestly and accurately assess RPE, the athlete is simply adrift in a sea of data that will not consistently help them improve either their training or racing approaches.
-Heart Rate Monitors
-Power Meters (e.g. PowerTap)
-Metabolic, Threshold and Aerobic Capacity Testing (e.g. New Leaf)
-GPS Pace Monitoring (e.g. Garmin)
-Impedence Body Composition Testing
But for all their value, these technologies do not replace the role of Rate of Perceived Exertion (RPE) in athletes' training and racing.
Defining RPE
The are two main scales for measuring RPE - a 9 point (1-10) and 15 point (6-20) - both developed by Borg. These scales are simple ratings of perceived exertion (RPE) used by many coaches and physiologists to assess an athlete’s level of intensity during training or testing sessions.
The 15-point scale is illustrated below as an example: point 6 would be the equivalent of sitting down doing nothing, 9 would be walking gently, 13 a steady exercising pace and 19/20 the hardest exercise you have ever done.
6
7 - Very, very light
8
9 - Very light
10
11 - Fairly light
12
13 - Moderately hard
14
15 - Hard
16
17 - Very hard
18
19 - Very, very hard
20 - Exhaustion
According to a 2002 study in the Journal of Sports Science, a team of Californian researchers found that, to varying degrees across genders and fitness levels, RPE correlated closely with VO2Max, blood lactate levels, heart rate, and MOST closely to ventilatory levels. The 15 point scale was most accurate, however, there was less confusion for athletes using the 9 point scale.
Measuring RPE
That correlation with ventilation, and the importance of having a clear rating system outside of the laboratory for training and racing, led me to develop the following RPE chart for my athletes to use:
I also like this one:
I encourage athletes to use "half-points" to fine tune the 9-point scale, especially at the high end, to differentiate between high/low end tempo and high/low end VO2Max efforts (e.g. start the two minute repeat at an 8.0 and end at a 8.5). This allows for cardiac drift, mental fatigue, and corresponding RPE drift.
In a laboratory or studio setting it is appropriate to use the 15-point scale and post it in front of the athlete so that they can refer to it and use a wider range of values to pinpoint exertion level.
The Appropriate Evolution of RPE in An Athlete's Development
As the study in the Journal of Sports Science found, "accuracy" of RPE is very much driven by fitness level and experience of an athlete. Someone new to running, for example, might identify themselves as at an RPE 8.0 as soon as then cannot speak in long, complete sentences - what an experienced athlete would correlate with an RPE of 5 -simply because they are not familiar with being out of breath and it is unsettling.
As a coach, however, I think this feedback is important and valid. The "downward" adjustment of RPE in less fit individuals helps prevent injuries and burnout. While that person might not progress as quickly in the short term as if they were working "harder", chances are that their progress will be greater over time because their training will progress more consistently. As their fitness improves and their experience working at more difficult intensities accumulates, their RPE:physiological benchmark (ventilation, HR, lactate, VO2Max %) relationship will become more accurate over time.
The Accuracy of RPE versus Data Collection Technology
Coaches often say that the accuracy of a power meter is less important than the precision. What does that mean? It means that the actual number the meter yields is not as important as making sure that the power meter yields the SAME number under the SAME application of force every time.
The opposite would seem to be true for RPE, however, since we can rarely reproduce all of the variables that go into performance output in an individual athlete, RPE can be the most accurate indicator of performance. Why? Because the human body reacts differently under the same application of stress depending upon many outside variables such as heat, humidity, air quality, mental arousal (adrenaline and other endocrine system releases), menstrual cycle, nutritional intake, training stress load, etc., and that reaction at any given moment can make or break a key training session or race.
Think about it this way: if I am time trialing on the ECV time trial course on a cool, cloudy day, I might record an RPE of 8.0 at my threshold watts of 200 and heart rate (HR) of 185 at minute 15. I had a night of good sleep, a day of good nutrition, and a rest day the day before. However, if I am time trialing at an indoor TT the day after being up with a sick child all night, and where the collective work of the participating athletes has driven the temperature and humidity up, and the available oxygen down, I might record an RPE of 9.5 at 200 watts and a HR of 179 at minute 15.
So RPE is less precise than wattage and HR as an instantaneous indicator of performance (speed). HOWEVER, if this is a 30 minute time trial in both cases, it is likely that I can sustain and even build from an RPE of 8.0 over the latter 15 minutes, but less likely that I can sustain or build from a 9.5. So in the first case it is likely that I can hold or even increase my watts towards the finish, whereas my watts are likely to falter pretty soon in the second scenario (I will spit the bit as they say).
If I pay attention only to wattage/HR as an indicator of correct pacing, then in the second scenario I will blow up, whereas I could have corrected for RPE earlier and finished strongly (albeit not as fast as on a day with ideal circumstances). And in the first scenario, I may very well underperform if I stay within wattage and HR zones, when RPE indicates that I could push harder in the latter stages of the race.
The key is monitoring performance and collecting benchmark data and correlating them to a variety of RPEs under different circumstances. Over time, the athlete will begin to understand more closely the variables that affect real and perceived exertion, and will be able to fine-tune their performances as a result. However, without the ability to honestly and accurately assess RPE, the athlete is simply adrift in a sea of data that will not consistently help them improve either their training or racing approaches.
Tuesday, May 25, 2010
Track RT
Here are the RT Videos that accompany track. Please note that these videos are meant to be used in conjunction with TriLife Coaching's track workouts and are not intended for any other purpose. You should always check with your physician before undertaking a new exercise program.
Please note that this hair style is not recommended for use except at the end of a long day of workouts ;)
These are meant to compliment speedwork and provide functional stability and oppositional muscle group strength for running. If you have any questions about how to do the exercises, please email me at april@trainingmeetstlc.com.
http://www.youtube.com/watch?v=a9WqWs_D_EY
Please note that this hair style is not recommended for use except at the end of a long day of workouts ;)
These are meant to compliment speedwork and provide functional stability and oppositional muscle group strength for running. If you have any questions about how to do the exercises, please email me at april@trainingmeetstlc.com.
http://www.youtube.com/watch?v=a9WqWs_D_EY
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