GETTING THE MOST FROM`BLOOD LACTATE TESTING

Note:  An edited version of this essay first appeared in the Oct. 2007 issue of Triathlete Magazine.

Definition:  As a by-product of metabolism, lactic acid is produced in several tissues of the body, including the muscles.  As it diffuses out of the muscles and other tissues, it appears in the blood as lactate.  A simple test determines the amount of lactate present in the blood measured as millimoles per liter.  The sampling procedure involves pricking the skin, obtaining a drop of blood on a test strip inserted in a meter.  The result is calculated and displayed 60 seconds after blood contacts the test strip.  The procedure includes safety standards to sterilize the skin sample site, to isolate and protect the client and the administrator, to obtain an uncontaminated sample, and for proper disposal of testing implements. 

Application:  In the context of endurance sports, blood lactate tests are conducted for two primary reasons:  1) By determining the athlete’s lactate threshold in correlation with perceived rate of exertion, heart rate, speed and/or power output, zones of intensity can be determined for effective training.  2) Through periodic testing with consistent and controlled variables (temperature, altitude, recovery, time of day, diet, etc.) it is possible to monitor progress during the athlete’s training and racing seasons, by comparing current results with past results.  Both of these applications are relevant specifically to the sport they are tested for.  In other words, a test for running will not provide applicable data for cycling.

Procedure:  In a conventional lactate threshold test, blood samples are tested: 1) At rest, before the athlete begins. 2) After 5 minutes at a sustained “Easy” pace. 3) After 5 minutes at a “Moderate” pace.  4) After 5 minutes at a “Moderately Hard” pace.  5) After 5 minutes at a “Hard” pace.  6) After 5 minutes at a “Very Hard” pace.  Another repetition at higher intensity can be added if there is no clear evidence of a rapid increase in lactate level.  The athlete pauses between increments only long enough to obtain the blood sample.  Average heart rate for the last 15 seconds of the 5-minute period (or for the entire 5 minute period) is noted, along with the blood lactate level.  In addition, speed and power output are recorded if available and relevant.  Upon completion of the sampling, a graph is generated.  Lactate threshold is determined to be at the onset of a rapid increase in blood lactate.

There are two very important factors to consider in this conventional testing procedure.  First, it is the athlete that is determining the level of intensity for each increment.  (The quoted intensity levels I have included above come from “The Training Intensity Handbook”, by Dr. John Hellemans, a noted expert in the field.)  Obviously these terms describe a subjective rate of perceived exertion (RPE); hence the blood lactate levels, heart rates, etc., are determined for perceived rates of intensity.  With a graph, it may be determined that the athlete crossed the threshold at some point during one of the 5 minute increments, and not precisely at the heart rate and blood sample time.  Therefore, the lactate threshold can be estimated somewhere between the sample increments. 

Second, there are many variables that influence the results, beyond RPE.  Some of these are listed above.  One thing is certain:  These variables will change on a daily and even hourly basis.  A coach or athlete who designs and conducts a training program solely “by the numbers”, by the heart rate, speed or power values associated with the blood lactate samples, is attempting to train “in the lab”, rather than the real world.  Athletes do not live in or race in the lab.  On the other hand, as a means of periodic testing to determine an athlete’s progress through the season, the lab context is valid, assuming that pertinent variables are held constant.  Heart rate training zones determined through blood lactate testing will vary constantly.

For its application in daily training, the big question is this: How can we get the most value out of blood lactate testing?  How does testing assist us in determining training zones and designing training programs?  How does testing apply to daily workout sessions?

Alternative Testing Protocols:  Before we address the big question, lets consider alternative protocols.  One alternative is to obtain the samples after the athlete has sustained activity for 5 minutes at specific heart rates, rather than at perceived rates of exertion.  If the athlete increases intensity at 5 or 10 heart beat increments between blood samples, the threshold determination may be more accurate.  As a variation on this, specific to cycling with a power meter, the athlete may increase intensity based on 5- or 10-watt increments.  Again, this will provide a more accurate determination.

The second alternative is to conduct a “Lactate Balance Point Test” as designed by Chlebek and Feldman of FaCT Canada.  (www.fact-canada.com.)  The athlete begins with 3 repetitions of 6 minutes.  This is the lactate buildup phase.  The first rep is at an easy warm up pace.  The second is at a moderate pace, say a half marathon or marathon pace.  The third is at a hard pace, say a 5K pace.  (Translate these intensities to cycling or swimming.)  Only after completing all three is the first blood lactate sample and heart rate obtained.   Lactate level is now very high.

Once the sample is obtained the athlete will begin a series of 5-minute intervals that comprise the lactate clearance phase.  The first interval is conducted at a heart rate 40 beats below the finishing heart rate of the last buildup interval.  At the end of this interval, blood lactate is sampled and recorded.  The second interval is conducted with a 10-beat increase in heart rate.  Again blood lactate is sampled and recorded.  For the rest of the test the intervals will be conducted with 5-beat increases in heart rate.  When blood lactate ceases to drop and begins to increase, the lactate balance point test is complete. 

This test closely determines the highest heart rate where the athlete is still clearly aerobic – able to clear lactate from the blood as lactic acid is produced in the muscles.  For long course endurance competition, this value may be more applicable than an estimated lactate threshold.  As with the conventional lactate threshold test, this test is specific to the sport tested and reflective of the many variables listed above that can change on a daily and hourly basis.

Ideal World:  Ideally, perhaps the athlete should test on a daily basis to correlate heart rates and/or power output levels with training zones for the specific sports of that day.  This would eliminate the subjective element of perceived exertion from the training equation.  However, at $90 per complete test, the monetary expense as well as the investment of time and energy makes this impractical, if not absurd.  Professional athletes will often test once a month during a recovery week to ascertain progress and redefine zones.  For most age group athletes however, even monthly testing for both biking and running is hard to justify at $180 per month.  For those who are earnest about performance, testing at the beginning of the Base Phase and again during the transition to the Build Phase for both bike and run can provide valuable guidance.  The athlete might consider testing again before the Peak Phase leading up to a goal race; however, if the values do not reflect high performance levels the athlete expected, this may be psychologically impairing.

Real Life:  As performance-oriented athletes, if we are investing a considerable amount of time and energy in training, and a considerable amount of money on gear, it might be wise to invest in blood lactate profiles for both biking and running.  These can provide a “reality check” in how we correlate the “soft” data of our subjective perceived rates of exertion with the “hard” data of heart rate, speed and power.  It can also provide us with training guidance by revealing what zones we are strong in and what zones we are lacking in.  If you choose to invest in a blood lactate profile, here are a few guidelines to help you get the most value from it:

Bang for the Buck:  The most important caveat is to realize that the specific heart rates, speeds, power values and training zones that are determined by the blood lactate levels are not to be regarded as absolute gospel.  They will fluctuate daily.  Rather, use the test as way of standardizing your perceived rates of exertion, as a way of fine-tuning your discernment.  When you are being tested, be very aware of your perceptions – your breath, discomfort levels, degradations in your pedaling or running efficiency, your cadence, the level of burn in your muscles, tingling in your extremities – in short all the clues that indicate your level of intensity.  Do not get lost in making this a “race performance” at the expense of recording your observations.  Create as many distinctions for yourself between your intensity zones as you can.  In fact, jot them down, or ask the test administrator or a friend to do so as you pause for each blood sample.

Effective training depends on the capacity to determine appropriate frequency, duration and intensity.  Frequency and duration are strictly quantifiable hard data.  Intensity however is based on a sliding relationship between the hard data of heart rate, power and speed, and the soft data of perceived exertion.  If the soft data slides “up” and the hard data slides “down” then the athlete is producing a higher relative output with less perceived effort.  This indicates adequate recovery and adaptation; the athlete is progressing and is ready for another breakthrough workout.  Conversely, if the soft data slides down and the hard data slides up, the athlete is producing a lower relative output with higher perceived effort.  She/he is still recovering and adapting from previous stress and should rest patiently before hammering again.  (Keep in mind that the source of stress may be something other than athletic, but this does not discount its impact.)

The athlete who has clearly standardized his/her perceptions into distinct zones of intensity can clearly perceive how the soft and hard data correlate moment by moment.  This standardization is the essential bridge between the “soft” data of your RPE and the “hard” data of heart rate, power and speed.  Certainly a sliding relationship also exists between heart rate versus output (power or speed).  This sliding relationship provides valuable clues for current athletic condition.  Keep in mind however that RPE can also slide in relation to heart rate for a specific sport.  Heart rate may be regarded as a kind of “intermediary” between soft data perception and hard data output.

For the budget conscious athlete willing to invest in only one such test to determine intensity zones based on a correlation of the soft and hard data mentioned above, choose your weakest sport – bike or run.  Correlating blood lactate with heart rates for swimming will have limited application, unless the athlete swims by heart rate.  Correlating to swim speed at a prescribed distance will provide more guidance, but remember that lanes in the middle of the pool are faster than end lanes, and that choice of swim wear also affects performance.  Instead, let swim technique dictate the intensity, frequency and duration of swim intervals.  When technique begins to diminish markedly, allow for a combination of more recovery and less intensity.  (Technique quality is equally valuable in dictating cycling and running intensity.)

Discuss the protocols your test administrator offers and determine what is appropriate for your level of training.  If you have a power meter on your bike, consider testing at 5- or 10-watt increments, and correlate heart rate, power and PRE.  If you do not train with a power meter, you must diligently correlate the blood lactate levels with heart rate and RPE.  Consider testing at 5- or 10-beat increments.  Make sure ahead of time that you are able to cycle (or run) at constant heart rates, plus or minus 2 beats.  If you are testing for running, remember that treadmill running does differ biomechanically from conventional road running.  You may choose to test at a running track instead, so you can still accurately determine your pace and correlate with heart rate and PRE.  In summary, correlating blood lactate and heart rate with bike or running speed does not provide reliable guidelines.  There are too many variables that affect speed – tires, shoes, wind, surface, temperature, humidity, topography, etc.

Preparing:  Many test administrators will recommend specific preparations before testing.  Some of these include:  Refrain from eating for 2 or 3 hours before the test.  Refrain from ingesting caffeine.  Refrain from long or hard training for at least 24 hours, allowing for adequate recovery.  However, if you are testing to define your training zones based on RPE correlated with heart rate, it might be best to conduct the test under conditions that closely mimic your usual training conditions for that sport.  If you usually train first thing in the morning, try to test at that time.  If you usually eat right before you train, or tank up on caffeine, you may get more applicable results if you test in the same condition.

There is an endless sea of scientific data to guide us in constructing and implementing triathlon training programs from sprint to ultra distance.  The pioneers in our sport served as the guinea pigs and lab rats.  We learn from their triumphs and their failures.  However, pick up any two triathlete magazines and you will find contrasting and conflicting protocols for training, nutrition, bike fitting, tapering and racing.  The plethora of data and experience at our fingertips is both a blessing and a curse.  There is much we can glean from it so we don’t have to re-invent the wheel.  However, if we conduct our training and racing solely by the numbers, precisely the way our tri hero did it back in the golden days with no regard to our own perceptions, then we are missing the whole point.  The quest in athletic excellence includes a relentless pursuit to hone our own senses, perceptions and discernment.

Blood lactate testing is an effective procedure for periodic testing to determine if our concocted alchemy of hard science and soft perception are advancing us towards our goals.  It is also an effective procedure for the novice to standardize his/her perceptions in correlation with heart rate, blood lactate levels and measurable output.  The bottom line is that we must integrate and harmonize the hard world of numbers with the soft world of perception.  This is the “magic”: the intuition and creativity of athletic excellence.

Enjoy it.

Shane Eversfield is author of “Zendurance, A Spiritual Fitness Guide for Endurance Athletes” and a Serotta certified bike fit specialist at High Peaks Cyclery, Lake Placid.