Post Number: 416
|Posted on Monday, May 12, 2008 - 02:00 pm: |
I thought first I may write a short answer , but than i decided to list here an answer from another author, as it is nice to see , that some of our ideas we regular publish here are not grown just on our field, but that more and more people start discussing publicly this topics.
Okay here the question, followed by a nice summary fo some ideas we so often discuss and than followed by a short question/suggestion to the asking person by myself.
The regular reader will very fast see where I like to go with the answer.
Hallo Christie from Ontario.
> Comments: I have been searching your forum for information on low resting
> lactate levels. I have a client whose lactate value consistently reads lo
> on the lactate pro at rest and after walking at 2.5 km/h. It says in the
> Lactate Pro Manual that if you get a consistent lo reading to consult a
> physician/doctor. Could you explain the reasoning behind this and where I
> could find research that explains why low resting lactate levels are a
As you will see in the following nice summary , there is one possible problem with "NO lactate" in the readings but easy to verify this.
• Problems in Determining Lactate Threshold
By Adam Baskin
A graded exercise test or field test with actual blood lactate sampling is the best way to accurately determine one's lactate threshold heart rate, pace or work-load.
The term "anaerobic threshold" has long been used synonymously with "lactate threshold," the blood lactate inflection point. The word "anaerobic" is defined as "without air." This terminology is a source of argument, as the onset of blood lactate accumulation offers no information about anaerobic metabolism and oxygen is present even at maximal exercise intensities (in healthy individuals).
Early models proposed linkages between a lack of oxygen in the working muscle, lactate production and changes in pulmonary ventilation. These causal linkages were attractive to researchers as lactate threshold could be estimated by observing the rate at which the athlete was breathing. Researchers called the point at which pulmonary ventilation and carbon dioxide output begin to increase exponentially "ventilatory threshold", which was observable as a substantial increase in breathing rate. Unfortunately, researchers later discovered that factors such as carbohydrate intake, body mass, mode of exercise and speed of movement all can affect ventilatory and lactate threshold determination.
Studies on patients with McArdle's syndrome place additional doubt on the anaerobic threshold – ventilatory threshold – lactate threshold relationship. McArdle's syndrome is a disorder where the sufferer lacks the enzyme phosphorylase, rendering them incapable of breaking down glycogen to form lactic acid. Even though McArdle's syndrome patients are incapable of producing lactic acid, they still demonstrate ventilatory threshold during graded exercise tests.
Therefore, it can be assumed that blood lactate levels are not directly linked to breathing rate. In studies using healthy young male subjects, glycogen levels were also found to affect the relationship between lactate threshold and ventilatory threshold. When glycogen was depleted in the subjects, ventilatory threshold occurred at a lower power output than lactate threshold, with both occurring lower as compared to test results for well fed subjects. Other studies have also found dissociation of the lactate threshold – ventilatory threshold relationship following an endurance training protocol.
Researchers sought an explanation as to why lactate threshold and ventilatory threshold sometimes occur simultaneously, even though blood lactate accumulation is not necessarily attributed to a lack of oxygen. As exercise intensity increases, fast-twitch muscle fibers are recruited, producing lactic acid regardless of whether or not oxygen is absent. Breathing rate during exercise is predominantly controlled by neural factors, mainly the carotid and aortic bodies, which are sensitive to the amount of oxygen and carbon dioxide present in arterial blood. While these factors may cause lactate threshold and ventilatory threshold to occur simultaneously, it does not necessarily indicate that the working muscles lacked oxygen.
Even though lactate threshold and ventilatory threshold occur simultaneously in some instances, it is still inappropriate to classify their occurrences as an anaerobic threshold. Recruitment of fast-twitch muscle fibers can cause lactate levels to rise regardless or whether or not the muscles are oxygen deficient. Lactate levels rise simply because production and release of lactate occurs at a rate faster than removal mechanisms can accommodate. Even at maximal exercise intensities, when the most oxygen is being utilized (VO2 max), the partial pressure of oxygen in the mitochondria never drops below critical levels. There are simply too many variables affecting ventilatory rate to use it to establish an athlete's training zones.
About the Author
Adam Baskin holds a degree in Clinical Exercise Physiology and is a Serotta Certified Bike Fit Technician as well as a USA Cycling Elite Coach. He works at the National Training Center in Clermont, Florida, conducting sports science tests including bike fits, LT and VO2 max. Baskin is also a Category 1 rider on the road and track.
National Training Center
1099 Citrus Tower Blvd.
Clermont, FL 34711
Now an addition more specific to your question.
Low readings on the lactate Pro does not mean no lactate , it is just below 0.8 so we see very often lo in read outs.
still low by walking of 2.5 km/h is very normal as well , as this is barely moving. You may have the odd COPD or cardiac patient where you may see some accumulation already but very rare.
The question in your person is , whether you ever see lactate before he or she feels very tired and has to stop the workout.
If yes you may have the check with the problem of a McArdle syndrom.
This is actually a very interesting situation, as this people can't simply spoken concert Glucose into energy ( not as simple ) So based on that we did a very simple connection some years back.
If the can not concert glucose to energy optimal or not , than that would mean that if we push the athlete to an "empty " glycogen tank we have a close to the same situation ( not as extreme ) but never the less we may see no lactate or very little lactate accumulation at the end of a race , where the athlete went far to hard to early in the race.
This will lead to 2 main informations we tried to gather.
1. End lactate compared with blood sugar and ammonia may give an indication on the situation in this athletes metabolic pattern at the end of the race.
That's when we started to check ammonia , as in Mc Ardle patients you can see an increase of ammonia and a lack of lactate..
So this is another nice example how we can use situations from other fields often seemingly unrelated to sport and use the information from this fields and transfer it over into sport.
We collected about 8 years back lot's of ammonia datas with our athletes and often many years later we see the full information slowly comming together .
In a test with a patient you may often see actually a low lactate or a rel. low lactate low and up to 0.9 - 1.1. Now if you start a test slow you will in nearly any case see a drop in lactate in the first few steps , so if you started by 0.9 you very likely will see a drop in to the low readings for 1 or 2 step. . Now interesting in this case you describe is the question , whether he is showing any read outs above and beyond 2.5 or whether that was his max. speed .
One possible sign you have with Mc Ardle is exhaustion in rel. low exercise intensity and possible muscle cramps.
And ammonia increase due to possible integration of protein to produce energy supply. Cramps due to possible deep "digging" into ATP production oxygen independent which drops the ATP lower than usual and can create cramps and it will take in this cases some time to get energy ( ATP ) out of protein as well as some mind work for this people to go that hard .
So thanks for the question and please come back if you have more info in this case Juerg