There are various methodologies used to benchmark an athletes physical condition and performance during training, understanding how they work is crucial for both an athlete and a coach. Each benchmark will be needed to be set up to match the individual athletes specific physiology and goals so understanding how they work is very important.
So what are the most common training benchmarks?
- Rate Of Perceived Exertion (RPE)
- Heart Rate
- Vo2 Max
- Anaerobic Threshold (AnT)
- Lactate Threshold (LT)
Below I will explain each one and how it is used and why.
Rate Of Perceived Exertion
The Rate of Perceived Exertion (RPE) scale is a subjective method to assess ones physical exertion or pain level . This scale was created in the 1960’s by Dr. Gunnar Borg, a swedish psychologist. Dr. Borg created two RPE scales, the 6 – 20 scale and the CR10 scale . The 6 – 20 scale is based on a scale from 6-20, with 6 representing the l lowest exertion /pain level and 20 being the highest level . The CR10 scale is similar to the 6 -20 scale however it ranges from 0 – 10 with 0 being no exertion and 10 being the highest. The RPE scale is used in both sports and medical settings.
Modified Borg CR10 Scale
Regardless of the type of RPE scale used, the scale is based on the athletes perception of exertion or pain and therefore is highly subjective. For example, someone with a high pain tolerance might rate running at 95% of their LT as a 6 on the RPE scale (Borg CR10), whereas someone with a lower pain tolerance might rate that effort level as a 9. While you cannot take the subjectivity out of the RPE scale, you can make an effort to try to assess an athletes intensity tolerance.
A good way to assess an athletes intensity tolerance is by using a Perceived Intensity Assessment (PIA). This is an important assessment because it gives you an indication of what you as an athlete’s interpretation of “intense” is. While you will never be able to say with 100% certainty if the RPE equates to the true corresponding physiological level of intensity, the PIA allows you to have a better idea of how physiologically accurate a athletes RPE number is.
The PIA assessment is as much a mental assessment as it is a physical one. You are using a physical exercise to perform a mental assessment of your tolerance of exertion. In this case, the mental assessment is based on pain tolerance.
Typically, former or current athletes rate quite high on this test as they are accustomed to exercising at a high intensity and have a relatively high pain tolerance. After performing the assessment, you will have a fairly good idea of where your intensity and pain tolerance lies. The purpose of this test is not to see how well the athlete completes the assessment, but rather the physical characteristics they show throughout the assessment, which in turn, can be used to decipher an athletes level of perceived exertion. This assessment should be done at the start of the training season or plan as well as throughout the training process to assess progression.
One of the reason I train close to my clients is to assess exactly this, certain sessions although functional and are required I also use as my own PIA to assess the athletes characteristics under certain intensities, and this gives me a better picture of the athletes abilities both physically and mentally and thus allows me to adjust training accordingly and in my eyes as a coach is crucial to developing any athlete.
Heart rate training has long been the standard when analyzing and assessing cardiovascular effort. Using a heart rate monitor (HRM) is a relatively inexpensive and beneficial way to assess effort level. Most heart rate monitors consist of two pieces, a watch and a chest strap. Some of the benefits of using a HRM are:
- An athlete can tell when they are not recovered. Without a HRM, this is hard to determine and forces the athlete to rely on how they feel which is not always the best measure. Below are three metrics that typically correlate to not being recovered and rested:
- Heart rate is slow to return to baseline after an effort.
- Abnormally high/low resting heart rate. An abnormally low heart rate is most common.
- Heart rate does not reach normal peak levels when putting out a corresponding effort.
2. HR is very useful especially during pre – season training when an athlete is working at their base fitness level. By using a HRM, an athlete can monitor their heart rate throughout the exercise session to make sure they do not push too hard. This is very important, because as a general rule of thumb, the more de-conditioned an athlete is, the higher their heart rate will be and the faster their heart rate will elevate with increased effort. This elevation in heart rate does not always correspond to the athlete feeling tired or putting forth excessive exertion. If you do not use a HRM with clients to measure heart rate during base fitness training, it is very easy for them to exercise too hard and not get the most out of the training process.
3. Training with an HRM can allow an athlete to set heart rate training zones. By setting these zones, an athlete can focus on varying intensities.
You can think of a heart rate monitor as a tachometer for the body. A tachometer in a car measures the number of revolutions per minute of the crankshaft in the engine. In this way, the tachometer shows how hard the car is working. On most tachometers you will see a red zone from approximately 7K RPMs and above. For this example, the 7K would represent the red line. The red line represents the beginning of an area that produces such high RPMs of the engine that it is potentially dangerous to keep increasing the RPMs above this level.
This is no different than your heart in terms of the red line. The red line, in human terms, is the maximum lactate steady state (MLSS). If an athlete were to continue to push past the his or hers MLSS, the athlete would be performing on borrowed time unless they lower their intensity. Like a car, an athlete cannot stay above the red line too long or at too high a level before performance decreases markedly and rapidly.
But also as an athlete you do need to know how your body feels or the correct perceived exertion at certain levels of intensity and this takes training to understand the feed back the body is giving you rather than just relying on the HRM. Race car drivers drive “by the seat of their pants” which means they listen to how the car feels and the sound of the engine to shift gears rather than looking at the tachometer …
Another thing you do have to realize, is that most commercial or consumer grade HR monitors are only 85-95% accurate especially in the higher intensities ..they are not regulated by the FDA as they are not a medical grade appliance.
That may not seem much but even a 5% drop inaccuracy at 160bpm is 8bpm .. so you think you are training with a perceived effort at 160 bpm when actually you are under training at 152 bpm or visa versa, having an effect of where you actually believe your perceived effort is mentally. This could also have a larger effect on mechanical efficiency during lower HR zones.
But HR monitors can have their advantages if used correctly as pointed out above, and the athlete and coach knows all the relevant parameters to manage this correctly, such as :
Estimated maximum heart rate
A long – established standard for determining an individual’s maximum heart rate has been the formula:
220 – Age = Maximum Heart Rate Based on the result of this formula, heart rate zones could be set to determine varying intensity workloads. There is just one problem with this formula … it’s a formula!
A formula is not practical in determining an individual’s maximum heart rate as there is too much of a range as to what one’s maximum heart rate could be. This needs to be assessed on an individual basis, not based on a set formula. Regardless, there is no scientific validity to the formula.
The 220 – Age formula was developed in the late 1960’s by cardiologist Sam Fox and physiologist William Haskell (350). The formula was derived in an attempt to estimate maximum heart rate for individuals undergoing stress testing. The formula was developed using a small sample of individuals. Interestingly, even Haskell noted that the formula was not intended for use in determining maximum heart rates of athletes.
Since this formula was developed, there have been attempts to identify a more accurate and scientific way to predict and estimate maximum heart rate. Perhaps the most valid was a 2001 study by Dr. Seals, a physiologist. Unlike Haskell and
Fox, Dr. Seal’s research drew on a data sample of a large number of subjects (over 18K) across hundreds of studies, including his own. What Dr. Seals found in regard to the standard formula (220 – Age) is the following:
- Overestimates maximum heart rate for young adults
- Fairly accurate for individuals around the age of 40
- Underestimates maximum heart rate in older adults
Based on his research, Dr. Seals proposed a revised formula:
208 – 0.7 x Age = Maximum Heart Rate A 2007 study by Gellish et al. corroborated Dr. Seal’s results and came up with a near exact formula (207 – 0.7 x Age – MaxHR).
The bottom Line – It is not advised to estimate maximum heart rate using a formula for the following reasons:
- You are not working in a clinical setting with cardiac patients that require you to determine their estimated maximum heart rates.
- If you are a coach and you are working one – on – one with clients, and therefore, can perform more valid and specific assessments on which to base intensity prescriptions.
- Any formula will likely have a relatively large degree of percent error.
- Utilizing MLSS as a benchmark for determining intensity zones is more accurate and functional than utilizing a percentage of maximum heart rate. Therefore, while a formula is not suggested, this information is critical to know and understand, as the 220 – Age formula is still widely used as an established benchmark for athletic cardiovascular programming.
Cardiac Drift (CD)
This is a phenomenon that relates to a natural increase or upward “drift” in heart rate while the overall intensity (e.g., respiration rate, effort level, caloric burn) remains the same. There are two primary reasons for cardiac drift):
- Increase in body temperature raises heart rate
- Decrease in muscular efficiency due to fatigue
CD has implications when designing a heart rate based training program. If a client experiences cardiac drift during training sessions that are based around heart rate, there is a strong likelihood that they will be under performing during the training sessions.
For example, let us say a client is supposed to train between 155 – 165 BPM. For the first half hour they are able to run at this pace easily while maintaining a 7:30 min/mile pace. However, at approximately 35 minutes into the run, cardiac drift brings their heart rate up to 168. At this point, the client slows down to stay in the appropriate heart rate training zone. By decreasing the effort level to accommodate for CD, the client is reducing their workload, whereas if they stayed at the same effort level (even though the heart rate would rise past the prescribed heart rate zone) they would be performing at the appropriate effort level.
Therefore, it is important to inform the client about CD and to judge their effort not just on heart rate, but also on perceived exertion. If you are aware that your client experiences CD as well as how many heartbeats they drift upward, you can consider assigning them a higher heart rate zone to take CD into consideration. In a 2000 study of 10 highly conditioned cyclists performing a MLSS test, CD was noted from the beginning to the end of the test.
Resting Heart Rate
This assessment is performed by taking ones heart rate upon waking and before getting out of bed.
This gives a good base measurement in terms of your client becoming more aerobically fit as well as when they are recovered. Generally speaking, the lower the resting heart rate, the more aerobically fit one is. However, individuals naturally have varying resting heart rate levels, so the value of this test is not the initial resting heart rate, but rather the reassessments.
Resting heart rate is affected by many things, so to obtain the most accurate baseline measurement, your client will want to read their resting heart rate on 3 – 4 consecutive days and average the results. Throughout the training process, and especially throughout the base training phase, your client should see the average resting heart rate decline.
A decrease in resting heart rate corresponds to an increase in stroke volume (amount of blood ejected with each heart stroke). When stroke volume increases, the heart beats less to supply the same amount of blood to the body as it would at a lower stroke volume.
This physiological adaptation is indicative of the cardiovascular system becoming more efficient and the heart not having to work as hard to supply the body with the blood supply needed. Typically the greater one’s age, the lower the resting heart rate. A significantly low or high resting heart rate can be indicative of not being recovered.
Recovery Heart Rate
The speed at which the heart rate drops can also be attributed to the fatigue level of an athlete. If an athlete is not recovered from a previous workout or is sick, the heart rate will not drop as fast as it would otherwise. Therefore, to get a true representation of the correct heart rate drop, the same test should be done different days and the average calculated. As your client becomes more aerobically fit, their average heart rate recovery time should decrease.
HEART RATE TRAINING ZONES
Results from the cardiovascular assessments will enable you to create intensity – based protocols for an athletes Heart rate training zones and allow the athlete to work within set parameters regarding intensity during training sessions. The higher the training zone number, the higher the intensity level. There are two primary types of heart rate charts:
- Based on an individual’s maximum heart rate and the zones expressed as percentages of the max heart rate.This method is not recommended.
- Based on an individual’s lactate threshold or more specifically, their Maximum Lactate Steady State MLSS). Using MLSS – based training zones, , heart rate levels are integrated. For example, an individual’s MLSS, Zone #4 might equate to a heart rate zone of 145 – 150 beats per minute (BPM).
The term maximum effort heart rate or VO2 Max is used a lot among endurance athletes and relates to maximal oxygen consumption, or more specifically, an individual’s maximal capacity to transport and use oxygen during exercise. The “V” stands for volume, “O2” stands for oxygen and “max” refers to maximum. VO2 Max also commonly refers to the test to determine a subject’s maximal oxygen consumption. So what does VO2 really represent?
A VO2 Max test can be done on any apparatus (e.g., bike, treadmill, rower, etc.), however the general method of testing is the same. The subject’s oxygen consumption is measured while the intensity of the effort increases. As the intensity of the effort is increased, the oxygen consumption also increases, initially as a linear relationship.
VO2 Max is represented when an individual’s oxygen consumption plateaus, even if the subject is able to continue increasing their effort. It is important to note that when performing a VO2 Max test, some individuals are not able to determine their VO2 Max because they fatigue before the oxygen consumption hits a plateau. Additionally, while it is normal to be able to increase one’s VO2 Max through exercise, the absolute limit of one’s potential VO2 Max is largely determined by genetics.
As noted below, some individuals do not reach a plateau. According to the American College of Sports Medicine (ACSM), an individual’s VO2 Max declines – 15% per decade past the age of 30. The good news is that ACSM found that older adults respond to aerobic exercise equally as well as younger adults in terms of increasing VO2 Max. This means that older adults can increase their VO2 Max by 10 – 30% through aerobic exercise.
In regard to increasing one’s VO2 Max, studies have found that increases in VO2 are mostly limited to recreational athletes versus well – trained (elite) athletes. Therefore performance increases in well – trained athletes are likely due to increases in running economy versus increases in VO2 Max.
An individual’s VO2 Max is typically expressed as millimeters of oxygen per kilogram of body weight per minute (ml/kg/min). For individuals that either should not or cannot do the VO2 Max test, there are estimated tests that do not take the individual to their absolute maximum.
These tests are also called sub – maximal tests and use equations to estimate their VO2 Max. While the VO2 test determines aerobic fitness, this test in isolation has often been found to be a poor determining factor of success in endurance athletes as there are many other factors that play into success.
Therefore, determining one’s VO2 Max is a great way to benchmark fitness and use for reassessment purposes, but in regard to performance in the real world, it is only one potential determining factor.
The primary reason why VO2 Max is often viewed as a poor indicator of performance is because of exercise economy. Exercise economy essentially relates to how efficient an athlete is. Many factors play into one’s exercise economy such as aerobic fitness, bio – mechanics and muscular endurance. To demonstrate how exercise economy fits into overall performance, let’s look at two hypothetical athletes. Both athletes (athlete A and athlete B) have a VO2 Max of 70 however athlete B is much more bio – mechanically efficient than athlete A.
If one were to look at just VO2 Max, they would both be identical in regards to potential, however when you look at the big picture that is exercise economy, it becomes clear that athlete B will outperform athlete A. In other words, athlete B has a greater exercise economy than that of athlete A.
When assessing athletes in regard to their potential as well as their current level, you must take into account exercise economy. To drive home this point, take for example Paula Radcliffe, arguably the world’s best female marathon runner ever. When tested (VO2 Max) initially as an 18 year old, and 11 years later, her VO2 Max did not change despite her vast improvement. Therefore it is easy to see in this case that her improvement was largely due to an increase in running economy, and not an increase in VO2 Max.
Sport Specific Fitness?
How is it possible that an individual could run a 2:30 marathon but barely make it one lap in a pool without hyperventilating and having their heart rate sky rocket. Are they out of shape? Not likely if they can run a 2:30 marathon. They are, however, inefficient when it comes to swimming and the wasted energy equates to their rapid rate of fatigue and elevated heart rate. This individual’s performance in the pool has no correlation whatsoever to their aerobic fitness level. It is just a question of what sport they are most efficient at.
While cardiovascular fitness is not sport specific, an individual’s overall efficiency is, which directly impacts the demand on the cardiovascular system.
Why not assess VO2 Max….?
The VO2 Max test is considered the gold standard in determining aerobic capacity. This test requires specialized equipment and training to administer. Sub – maximal tests are used to estimate the VO2 Max for individuals for whom a true VO2 test would be unsafe or for those who do not have access to a VO2 Max test, or simply do not want the full test. As a side note, a VO2 Max test typically costs $100 – $300 and is often done in conjunction with a blood lactate threshold test.
As noted previously, VO2 Max, by itself, is often a poor indicator of performance, as it does not take into account exercise economy. This is where correlating blood lactate is valuable to know. For example, two athletes could have the exact same VO2 Max, but different blood lactate levels. VO2 Max relates to aerobic capacity but lactate threshold (LT) determines what percentage of their VO2 they can perform at and for how long. This was demonstrated in a 1982 study by Bertil Sjodin. In this study, runners performed training essions at lactate threshold for 14 – weeks.
At the end of the 14 – weeks, the subjects decreased their average mile time from 5:43/mile to 5:29/mile. Interestingly, the VO2 max of the runners did not increase at all! While it might be interesting to know one’s VO2 Max, from a training perspective, you should be more focused on the heart Rate — specifically the final heart rate when the client can no longer continue. This is because VO2 Max expressed as ml/kg/min cannot be correlated directly to other aerobic fitness benchmarks, whereas heart rate can.
When compared to a true VO2 Max test, many of the estimated VO2 Max tests underestimated one’s VO2 Max.
Assessing Maximal Aerobic Heart Rate
While one’s VO2 Max expressed as ml/kg/min does not hold substantial value in relation to benchmarking training parameters, one’s maximal aerobic heart rate is of value for the creation of training zones. The Maximum Aerobic Heart Rate will be used to help benchmark LT (MLSS) based training zones. Prior to the end of the assessment, the increase in heart rate will typically slow or plateau. This is indicative of a maximum or near maximum effort.
Variables with the Maximal Aerobic Heart Rate Assessment
- If an athlete is extremely deconditioned, they will likely not be able to reach their maximum aerobic heart rate level due to systemic fatigue.
- If your client has a low pain tolerance or they may stop the test before their maximum aerobic heart rate is reached.
- If an athlete is new to running, their heart rate may be “artificially” high due to a low running economy. Additionally, their legs may fatigue before they reach their aerobic capacity.
- If an athlete is fatigued, their heart rate may be higher or lower than normal, depending on how their body responds to stress when fatigued.
Typically the heart rate response is reduced. If you believe that an athlete fits nto any of these scenarios, be advised that the maximum aerobic heart rate may have some degree of error.
Anaerobic Threshold: Fact or Fiction ??
The term Anaerobic Threshold (AnT) is used extensively in the world of endurance sports and most commonly used to describe the working upper limit of one’s aerobic capacity. AnT is difficult to define as it is more of a concept than an established metric. It should be noted that some individuals do not believe that AnT exists.
Due to this, there are many different interpretations regarding what AnT is. In addition to confusion about what the definition of AnT is, it makes sense that there is equal confusion over how to assess and estimate it.
Some of the most common benchmarks used to interpret AnT are:
- Lactate Threshold (LT) Representative of the level at which blood lactate accumulates in the blood stream. This occurs when lactate production exceeds lactate clearing.
- Maximum Lactate Steady State (MLSS) The highest intensity level at which blood lactate concentrations are maintained at a steady state (equilibrium) level during exercise bouts of at least 60 minutes (This may or may not be higher than OBLA).
- Ventilatory Threshold (VT) The point at which the ventilation rate increases faster than the workload. Until the VT is reached, the workload and respiration rate increase linearly. Often correlated with LT.
- Onset of Blood Lactate Accumulation (OBLA) OBLA is often used synonymously with LT however OBLA occurs at a slightly higher level than LT (71, 125). Technically speaking, OBLA is reached when the blood lactate accumulates to a certain level in the blood (4mmol).
A primary reason for the increase in popularity of quantifying AnT in sports is the poor correlation between VO2 Max and athletic performance. As a result, finding a sub – maximal threshold that can be maintained over long periods of time has gained traction within the endurance sports community.
While the AnT interpretations noted above have value to runners when gauging intensity, they should not be used to directly infer AnT. This is primarily due to a lack of correlation between assessment methods. For example, a 1993 study out of the University of British Columbia found that when using VT and LT to estimate AnT, many of the correlations appeared to be coincidental.
The theory that a coincidental correlation exists between AnT, VT, and LT is further supported by a 1982 study that looked at hyperventilation rates in people with Glucose Storage Disease – Type 5 (commonly called McArdle Syndrome). Individuals with McArdle’s syndrome cannot break down glycogen in the muscles. As blood lactate is the result of glycogen breakdown (catabolism), these individuals do not produce lactate above resting levels with exercise. In this study, the participant’s VT increases at the point at which their proposed AnT would be. This demonstrates that VT is not caused by an increase in LT. Therefore, the assessments that are noted above, as well as others, should be used as stand – alone assessments, but not for the purposes of inferring AnT.
The implication of a proposed AnT is that once an individual exceeds it, they are no longer using oxygen for energy, but rather relying on glycogen exclusively for energy. This is erroneous as there is no evidence that the body “switches” from using oxygen to not using oxygen at a particular intensity level. Oxygen is present at all levels of intensity, albeit in varying amounts. At one’s proposed AnT, the anaerobic energy systems do not take over from the aerobic energy system, but supplements it to meet the increased energy demand.
Origin of Anaerobic Threshold
The term anaerobic threshold was coined by Wasserman and McIlroy in 1964 as a way to identify an intensity that was challenging and safe for cardiac patients (136). The goal of anaerobic threshold was to identify a reliable, submaximal effort level so that cardiac patients were not subjected to maximal cardiovascular tests. The premise of their Anaerobic Threshold Theory was that blood lactate accumulation is the result of poor oxygen levels (127).
Lactate Threshold (LT)
Lactate threshold is representative of the level at which blood lactate accumulates in the blood stream. This occurs when lactate production exceeds lactate clearing. While there is always lactate being produced, at rest or at low to moderate intensities of exercise, the lactate is ‘cleared’ within the muscle.
So what exactly does ‘cleared’ mean and how does this influence LT? In regard to LT, when you see the term ‘cleared’ … think ‘used for energy. Lactate is cleared intra – muscularly by:
- Oxidizing the lactate and converting it back to pyruvate (oxidative fuel) within the muscle which lactate was formed. Lactate is used for fuel in the mitochondria. Lactate permeates the mitochondrial wall via a special ransporter protein called, monocarboxylate transporters (MCT’s). MCT’s can be increased via training, thus facilitating increased lactate clearance.
This clearing method prevent s the intra – muscular lactate levels from increasing too fast to the point where lactate levels reach the intra – muscular threshold and spill out into the blood stream. Therefore intra – muscular lactate levels can increase substantially (up to 5 times resting levels) without any increase in blood lactate levels. However when the intra – muscular lactate threshold is breached, some lactate exits the muscle and enters the circulatory system and thus increases blood lactate levels. This is representative of the lactate threshold.
An analogy to this would be to equate a muscle fiber to a drinking glass, the water within the glass to lactate, and any area outside the glass to the circulatory system. Levels of water (i.e. lactate) can increase and decrease but
so long as the levels do not breach the top of the glass (i.e. lactate threshold), the blood lactate levels will not increase. However once the water spills over the top of the glass, the blood lactate levels increase as there is an increase in lactate within the circulatory system.
Once blood lactate enters the circulatory system, it is shuttled to areas of the body that can use it for fuel (i.e. brain, heart other skeletal muscle). Blood lactate that is not utilized is sent to the liver where it is first converted to pyruvate, then to glucose – to be used by muscles as fuel. This is representative of the Cori Cycle.
When exercising at MLSS, most lactate is oxidized for fuel via converting lactate to pyruvate and back to lactate. When the intensity increases much beyond MLSS, the lactate enters the circulatory system. The process by which lactate moves Intra – muscularly and throughout the circulatory system is termed the Lactate Shuttle.
As lactate can be added and removed from the blood, the amount of blood lactate at any given point is representative of blood lactate accumulation, not production.
A bit of Historical Reference
In addition to Dr. Meyerof’s frog study which he concluded that high levels of lactate caused muscular fatigue (24), there are two other studies that have had a profound impact regarding the erroneous perception of lactate. In 1857, a biochemist named Louis Pasteur deduced that lactic acid formation was only possible in the absence of oxygen (anaerobic). This is called the ‘Pasteur Effect’.
Secondly, in 1923, research by physiologist A.V. Hill theorized a correlation of high work levels to high blood lactate levels. More specifically, he theorized that at high intensities, the aerobic system was not adequate to provide fuel to the body and therefore the anaerobic /lactic acid system would ‘switch on’ and take over from the oxidative system. In the years since then, the following has been found to be true:
- Lactic acid does not exist within the human body
- Lactate is a fuel
- Lactate is produced at all times
- The proposed anaerobic system does not ‘switch – on’ after the oxidative system is exhausted.
- Lactate is not responsible for muscle burn
Despite these findings, there is still a large consensus that believes that lactate is a waste product and responsible for a reduction in human athletic performance.
LT has become a common benchmark for gauging intensity during training and racing in endurance sports. However like anaerobic threshold noted above, the method by which LT is assessed and quantified is equally as confusing.
LT benchmarks such as OBLA, MLSS and LT itself are often viewed as being synonymous. As noted above, LT, OBLA and MLSS occur at slightly different levels of intensity. Perform an online search of LT assessment methods and you are sure to find quite a few different methods, charts, graphs, and philosophies regarding the best way to assess and benchmark LT. However the only method and the only benchmark that I would be interested in is MLSS. This because MLSS has the highest correlation to endurance training and racing.
MLSS Associated Heart Rate
Historically, heart rate as a percentage of one’s estimated maximum heart rate was the primary indicator of intensity. Heart rate has a valid place in benchmarking intensity, however it is best used when correlated with MLSS.
The key reason for MLSS being the new standard for gauging intensity is due to its direct correlation with muscle fatigue, and thus, sustainability of exercise. When using an accurate MLSS level as a benchmark, an athlete is able to perform at sustainable levels for relatively long duration’s.
According to running coach Dr. Jason Karp, running at ones LT should feel, “comfortably hard.”
From an endurance athlete or coaches point of interest the more data points there are, the more accurate it is to benchmark intensity and thus training zones. So the two primary data points to determine are:
- Maximum Aerobic Effort Heart Rate
- maximum Lactate Steady State (MLSS)
By performing these assessments, you will be able to accurately denote LT – based heart rate zones. However of the two assessments, MLSS is the more useful.
Blood Lactate Clearance
Lactate clearance was discussed above in terms of being cleared intra – muscularly. However once the lactate threshold is reached and the lactate enters the circulatory system, lactate becomes blood lactate and is cleared in one of two Ways:
- Lactate is shuttled to areas of the body that can use it for fuel (i.e. brain, heart other skeletal muscle).
- Blood lactate that is not utilized is sent to the liver where it is first converted to pyruvate, then to glucose. This is representative of the Cori Cycle.
When blood lactate levels increase past what can be cleared, blood lactate begins to accumulate. In a 1989 study by McMaster et al., swimmers were assessed to determine the best intensity level to clear lactate back to a base level amount after a maximal effort. McMaster et al. found that when swimmers swam at 65% of their maximum effort , they cleared the most lactate.
This study was performed using swimmers because during meets, swimmers often have to compete in multiple events, thus necessitating proper recovery from one event to the next.
Another study found that exercising near to one’s LT cleared the most lactate. This study also found that lactate was cleared faster via active rest than at rest. While the first study noted is specific to swimming, the science likely holds true for that of running. It is applicable from both a perspective of recovering during competition as well as during training when performing interval – type sessions.
The positive effects of active recovery in regard to clearing lactate seem be limited to 20 minutes or less.
While physical training has no impact on the body in regard to lactate production, it does influence the ability of an individual to clear lactate. Interval – based training is the most efficient way to increase one’s ability to clear blood lactate.
As you can see there are a lot of on going assessments requires to manage and get the best out of each benchmark with reference to an athletes training and performance, having carried out assessments on my self regularly and developed many different training programs based in and around all of these benchmarks, and I still find the best way to monitor and assess on going performance is by using your head and taking the feed back from your body and understanding what is going on.
What you have to remember if you are using a benchmark to gauge your training parameters and performance then these assessments need to be carried out periodically through out a training season, and benchmarks amended as performance and efficiency increase. Otherwise performance will plateau ..
With Reference to using HRM all the time during training I don’t, as there are to many variables can influence them in real world training, and I have seen to many people be influenced by what their HRM is saying rather than listening to their body and either quit or under perform. I don’t use them in any event so I need to be trained accordingly to listen to my body. I do use them to assess my self to check benchmarks, also to check recovery by testing HR first thing in the mornings.
Understanding benchmarks and how they relate not only to your sport and required endurance training, but how they relate to your physiology is as I said very important, not understanding them and getting them wrong can seriously effect how you train, perform & recover.
Remember the Specificity of Sport Disciplines