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Lactate Threshold

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There is good evidence that endurance training changes Lactate Threshold. However, the idea that training at threshold intensity, such as [[Tempo Runs]], is particularly effective has no evidence<ref name="Beneke-2011"/>"/><ref name="Guellich-2010"/>, and polarized training is a better approach<ref name="StögglSperlich2014"/><ref name="Muñoz-2014"/>. For trained athletes, Tempo runs are ineffective<ref name="Londeree-1997"/> and may actually be counterproductive<ref name="Evertsen-2001"/><ref name="Guellich-2010"/>. See [[Tempo Runs]] for more details.
Detraining shifts will reduce the Lactate Threshold<ref name="Coyle-1985"/>, and Lactate levels can be higher at a given intensity after just a few days without training<ref name="Mujika-2001"/>, suggesting rapid detraining effects. The improvements in Lactate Threshold pace are largely due to a greater rate of Lactate removal rather than reduced rate of production<ref name="Phillips-1995"/><ref name="MacRae-1992"/><ref name="Donovan-1989"/><ref name="Donovan-1983"/><ref name="Bergman-1999"/>.
=The Usefulness of Lactate Threshold=
One of the primary goals of Lactate Threshold testing is to determine the correct pace for [[Tempo Runs]]. However, even if Tempo training is ineffective there are two good reasons for knowing your Lactate Threshold. Firstly, monitoring Lactate Threshold is a great way of evaluating the effectiveness of a training regime. Secondly, Lactate Threshold can be used to validate race pace goals. If your Lactate Threshold suggests a much faster race pace than you've been able to achieve, it suggests either a lack of resistance to muscular damage or a lack of mental fortitude. If the Lactate Threshold suggests a race pace that is slower than your target goal, it suggests you objective is wrong and you should aim for a slower finish time. This is especially important in the marathon, where "hitting the wall" is a common issue.
Because MLSS is time consuming and expensive, a shortcut is often used to estimate MLSS by assuming that it occurs at a fixed Lactate Level (Fixed Blood Lactate Accumulation, or FBLA)<ref name="De SouzaGrossl2012"/>, unusually 4.0 mmol/l<ref name="Heck-1985"/> though sometimes 3.5 mmol/l<ref name="DenadaiFigueira2004"/><ref name="Denadai-2005"/>. However, while the MLSS may average around 4.0 mmol/l<ref name="Denadai-2005"/>, there are significant differences for individuals<ref name="Mamen-2009"/>, with variations between 3.0 and 5.5 in small sample sizes<ref name="Heck-1985"/> and has been shown to have a range as wide as 2.0 to 10.0 mmol/l<ref name="Faude-2009"/><ref name="Stegmann-1981"/>. This approach also typically uses a blood test, but in some sports (like running), the athlete has to pause to have a pinprick blood sample taken, further confusing the test<ref name="Heck-1985"/>. The term "Individual Anaerobic Threshold" (IAT) has been used to emphasize that the Lactate Threshold is specific to each individual rather than using a FBLA, though this can refer to a specific protocol for estimating MLSS<ref name="Stegmann-1981"/>. The Fixed Blood Lactate Accumulation is sometimes called "Onset of Blood Lactate Accumulation" (OBLA)<ref name="Mamen-2009"/>, a particularly misleading term in this context.
==Lactate Threshold Estimation From Lactate Patterns==
There have been several approaches to determining MLSS without the difficulty of the full protocol<ref name="Billat-1994"/><ref name="Harnish-2001"/><ref name="Palmer-1999"/><ref name="Tegtbur-1993"/><ref name="Dickhuth-1999"/><ref name="Urhausen-1993"/>, but their validity is limited<ref name="Kilding-2005"/><ref name="De SouzaGrossl2012"/><ref name="Beneke-1995"/><ref name="Jones-1998"/>. These approaches generally look for some pattern in the change of Lactate level.
For example, one approach called the "Lactate Minimum Speed Test" (LMST) uses an initial sprint to elevate blood lactate followed by an incremental power test<ref name="SoteroPardono2009"/><ref name="Sotero-2009"/><ref name="MiyagiLeite2013"/>. However, the effectiveness of the LMST is profoundly impacted by the starting speed of the incremental portion of the test<ref name="Carter-1999"/>and so the results may be coincidence<ref name="Carter-2000"/>. This is not entirely surprising given the initial sprint phase disrupts the metabolism<ref name="Carter-2000"/>.
Some trivial approaches have been tried, such as looking for a 1 mmol/l increase followed by another 1 mmol/l increase<ref name="CTS"/>. So for an athlete performing an incremental load test with [[Lactate]] readings of 1.7, 2.3, 2.6, 3.7, & 5.6 the conclusion would be their Lactate Threshold is 3.7 (3.7 is more than 1.0 more than 2.6 and followed by another increment of more than 1.0.) However, given that most portable Lactate meters have a Typical Error of 0.4-1.0 mmol/l<ref name="Tanner-2010"/>, a fractional error in the reading gives a different result. In the previous example, if the 2.6 reading was 2.8, then the Lactate Threshold would jump from 3.7 to 5.6.
Some of the tests could be "p-hacking", where the study looks at a sufficiently large number of variables that some correlation occurs randomly<ref name="HeadHolman2015"/>.
[[File:LactateComp.jpg|none|thumb|500px|The correlation (or lack thereof) between MLSS and the lactate levels at the MLSS intensity seen during 3 or 5 minute incremental power tests<ref name="Heck-1985"/>.]]
One approach that looks promising uses three tests to estimate MLSS<ref name="Billat-1994"/>. First, a standard incremental test is used to give a rough estimate of MLSS. Then two 30 minute tests are performed, one above and one below the rough estimate of MLSS. The relative difference in rise between the two tests is then used to estimate the crossover point. For instance assume running at 7:00 min/mile produced a blood lactate that fell from 4 mmol/l at 5 min to 3 mmol/l at 20 min, a 1 mmol/l drop. Then a run at In the run at 6:20 min/mile the blood lactate rose from 4.0 mmol/l at 5 min to 6.5 mmol/l at 20 min, a 1.5 mmol/l rise. The interception point would then be about a MLSS pace of 6:26 min/mile. This is not much less effort than the full MLSS test, but it is an improvement.
==Lactate Threshold And Near Infrared Spectroscopy==
A promising technology for measuring Lactate Threshold is Near-infrared spectroscopy (NIRS) which shines infrared light into the skin above an active muscle and measures the reflected light. NIRS measures the oxygen saturation in the capillaries of the muscle and has the potential to test for Lactate Threshold without any blood sampling. Because NIRS can monitor continually, it is possible that it may be able to determine the Lactate Threshold during an incremental test rather than requiring the multiple tests of MLSS.
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