What is Lactate Testing?
In this article we aim to answer the most asked questions we get when it comes to all things VO2 max testing. These will include:
1. What is blood lactate, why is it important and what it tells us about you as an athlete?
2. What is the point in lactate testing and what do we do with the results?
3. What does a lactate testing entail, how do I know it is accurate and where can you get tested?
4. What is the difference between lab-based lactate testing and training zones and training zones on your smart watch (Garmin, Apple Watch, Coros, Suunto, Whoop etc)?
What is blood lactate, why is it important and what it tells us about you as an athlete?
Despite what many people think, lactate is not some waster product to be feared. In fact, it is a perfectly fine fuel source for our muscle cells and can be converted back into the storage form of carbohydrate in the body, glycogen, through a process called the Cori cycle.
So why do we measure lactate? Lactate is produced in the muscle cells when carbohydrates, in the form of glucose (either directly from the blood or the breakdown of glycogen stored in the muscles) can’t be fully converted to energy.
Why can’t glucose be fully converted to energy? Well under aerobic conditions when we can provide the body with enough oxygen it can. However, if our muscles demand energy at a rate that we cannot meet through our normal aerobic pathways, then we can produce energy by breaking down glucose but because we don’t have enough oxygen available only part of the pathway that uses up the glucose can be accessed.
This ‘anaerobic’ pathway only partly breaks down the glucose and accesses only a small proportion of the energy available from this molecule in the form of ATP.
ATP is the bodies energy currency that facilates every process in the body, including muscle contractions.
If we take one glucose molecule and use that to produce energy when there is enough oxygen available to fully oxidise glucose, we create 38 molecules of ATP, under these anaerobic conditions we only get 2 molecules!!
Fat breakdown (fatty acids) in the body varies in the number of molecules of ATP created due to the fatty acids we breakdown having different structures. But this is typically in excess of 120 ATP per fatty acid chain.
The problem with fat usage is that it demands a lot of oxygen and only produces ATP relatively slowly. Hence why we switch the proportion of energy being produced from more fat dominant to more carbohydrate dominant pathways, as we work at higher intensities and demand more energy at a higher rate.
This is important to note. It is not simply the energy demand that increases, it is the rate of energy demand that fat (fatty acids) simply can’t keep up with.
Fun fact: When we are exercising in aerobic conditions utilising stored fat or carbohydrate to produce energy and this is fully metabolised to produce energy, the waste products are carbon dioxide and water… this means that when you burn stored body fat (or carbohydrate) you are literally breathing it out!
As we discussed earlier, it is not actually the lactate that is the issue. It is the fact that as we produce lactate, we also produce hydrogen ions. These create a more acid environment in the muscle that they do not like, this impairs function, and we need to slow down to allow the body to remove these ions before they cause cell death.
In summary: Lactate is an indicator of acidity levels in the body. When lactate levels rise beyond a certain point then we are operating on borrowed time.
What lactate tells you as an athlete?
As we work harder and produce lactate, the amount we produce corresponds with metabolic pathways in the body and defines thresholds and tolerances to lactate that indicate training zones.
Testing for lactate tells you where these zones are. Training in specific zones targets specific adaptations and therefore lactate testing can be used to both profile your strengths and weaknesses as an athlete, pacing zones for races and combined with heart rate data to create a plan with paces and powers that you have confidence are hitting the proper zones… unfortunately just using percentages of heart rate aren’t accurate enough for those who really want to be accurate with their training.
Some elite athletes will even take lactate measures during training sessions to ensure they are in the right zones. Unless you can afford the kit and know how to use it, the best you can do is regular testing to find the relationship between lactate, heart rate, pace/power and perceived effort to use these to create more accurate training programs.
If you are looking for ‘lactate testing near me’ then aside from our London locations, we also have hubs throughout the UK where we can offer performance testing. So please don’t hesitate to get in touch and I’m sure we can find a location to get your numbers tested.
What does lactate measurement look like?
To create a full performance profile, we combine this with maximal oxygen uptake testing, which we have discussed in this article here.
The lactate test involves a small pin prick blood sample to the finger or earlobe that is then collected on a special strip attached to a device that reads lactate levels.
Usually, because of how well people bleed we can get 2-3 samples from each pin prick, so you won’t feel like a pin cushion at the end.
Each sample is taken at increments of around 3 minutes that correspond to different effort levels. This is performed either on the treadmill or a Wattbike depending on which is most appropriate for your sports 9or perhaps both for triathletes)
Speed/Power is increased by an amount that takes you from a resting level of effort to a maximum effort, where the end of the test is determined by when you feel you reach a point you can’t continue. This doesn’t have to be the point at complete collapse, we will have all the data we need at this point to produce your report with training zones etc.
The amount of increment we use at each level depends on you as an athlete, so we ask some questions about your current race times, paces, training output etc. to create a protocol that works best for you to measure your zones accurately.
On the Wattbike sampling can take place whilst you keep on cycling, once the sample is collected then we increase the workload for the next 3 minute interval.
On a treadmill, we have to hop off onto the side to collect the sample before matching the treadmill speed and increasing it for the next interval.
Each sample takes around 10-30 seconds to collect depending on how well you bleed!! but don’t worry, having to hop onto the side of the treadmill and ‘rest’ doesn’t affect the data we are after.
What are your lactate Zones?
During the test we are looking to use changes in lactate at different effort levels to determine your zones.
There are two main systems that are used to look at lactate. A 3-Zone and 5-Zone system.
The 3-zone system identifies the 2 key lactate thresholds. These are given as LT 1 and LT 2 on the image below.
LT1 corresponds with the first change in Lactate above baseline levels.
LT2 corresponds to the big inflection point on the image below.
Effort levels below LT1 would be considered easy effort aerobic session.
Between LT1 and LT2 would be our moderate effort tempo/sweet spot work and at LT2 this would be considered ‘Threshold work’
Above LT2 we are accumulating lactate at a high rate and this would typically be used as the cut off to say we are in anaerobic, high intensity zones.
The 5-Zone system uses more defined values that we look for on your test. LT1 and LT2 are still important landmarks, but we also define sub-zones if possible. Although this can be challenging in certain people who have very small zones, so differentiation between them can be difficult.
The Zone system we report in your testing depends on how well we can define your zones from testing. The fitter you are, the easier this typically is.
When you hear about Zone-2 training (article here) this is referring to the 5-Zone system. In the 3-Zone system this would be Zone-1… confusing, right?
The 5-Zone system values are reported as follows:
Zone 1: Active Recovery - Lactate levels below 2.0 mmol/L.
Zone 2: Easy Effort - Lactate levels between 2.0-2.5 mmol/L.
Zone 3: Tempo - Lactate levels between 2.5-3.0 mmol/L.
Zone 4: Threshold - Lactate levels between 3.0-4.0 mmol/L
Zone 5: Anaerobic Zone - Lactate levels above 4.0 mmol/L
How do I know lactate testing is accurate?
This largely comes down to the equipment used. We use gold standard equipment that is highly accurate, and testing is performed by only highly skilled people who have undertaken rigorous training.
This final point is important because making sure you get the insight that you need means that we need to know the data is correct and what we would expect to find to create proper insight. Being able to use equipment and interpret it correctly are too different things. We make sure we can do both!
How do these Zones compare to your smartwatch or heart rate monitor predicted Zones?
The answer to this we will keep short and sweet, the answer is ‘not very’. Whereas testing using our lab set up directly measures lactate smart watches use a simple formula based off heart rate alone.
We often find large differences between the Zones created using percentages of maximum heart rate and our testing. This is important for a few reasons.
If we are concerned with accuracy to fully profile ourselves as athletes and identify limiters of performance and how to overcome them, then we need to know where your strengths and weaknesses lie and to ensure training is targeting those weaknesses.
It is also important to know we are operating at the right intensity to ensure that we are creating the right stimulus and understand the type of energy system and fatigue we are creating.
This is why it is important to have testing performed by experts who understand the ‘reality’ of the data and how to extract meaningful conclusions.
