Science – FTP and Blood Lactate Testing

Blood Lactate Test

This article will assume you have some knowledge of power based training. Most readers will have heard the term FTP before, maybe not.

At some point you may have asked the following questions.

  • What is FTP?
  • How do I know my FTP?
  • What does it all mean?

I’m not a sports scientist nor a genius by any means but can sometimes make sense of graphs and interpret data points in an attempt to objectively assess physiology. This article will attempt to put a chaos of thoughts into words.

Functional Threshold Power

What is FTP?

FTP stands for functional threshold power and is a metric used in power based training. 

It is a number based on a test protocol developed by Andy Coggan, quoted in watts. Variants of the metric exist which are similar but differ slightly. These variants are measured using different testing protocols, one example is CP (critical power).

Simply put FTP is the maximum number of watts an athlete can hold for an hour at a constant effort.

It is (around) the level at which your body can sustain an aerobic workload.

Aerobic workload is where the body uses oxygen to continue converting ATP to energy, without building up excess waste product in the muscle.

Anaerobic workload is where there is not enough oxygen to sustain the conversion and the muscle is unable to clear waste product as it is created, therefore ‘buffering’ the waste product. This ‘buffer’ only starts clearing once energy demands reduce below the anaerobic level. 

kinda science

How do I know my FTP?

There are many test protocols to calculate your FTP. I won’t cover the benefits and differences here but will link to some articles.

What does it all mean?


If you are looking to excel your training and progress to the next level then knowing your FTP and training using a power meter can be an excellent method. 

Simply knowing your FTP doesn’t give you all the information though. The 4D power profile from Sufferfest tries to fill in some of the gaps, but still leaves somethings up to assumptions.

With all the above methods of evaluating FTP there is a fundamental assumption about how your body deals with generating power; the effects of the physical exertion.


You might be a rider who has an FTP of 290 watts, weighing 70 kilograms. Making for a very respectable 4.14 w/kg FTP.

You might find it relatively easy holding your FTP power for the first hour of a ride while your body is fresh. How about a 2 hour ride, could you ride easy for the first hour, and then hold that FTP power for the second hour? What about a 3 hour ride?

Simply knowing your FTP won’t give you a true indication as to how your body deals with fatigue or how effective and efficient it is. You can quickly see FTP does not tell us the whole story when it comes to power based training.


How do you know if your body is able to sustain a high level of output for an extended duration? You need to look at other metrics which are a response to the physical exertion.

Heart rate (HR) is a good metric to couple with Power, when you increase your power output your HR goes up in relation to the relative effort. We can go one step further and measure the blood lactate to directly see the effectiveness of your aerobic and anaerobic systems.

Without going down a rabbit hole of blood lactate and measurement methods let’s appreciate there is a relationship between power output, heart rate and blood lactate.

Blood Lactate Testing

Blood lactate testing gives you a clearer insight into the relationship between power output, heart rate and blood lactate. This will give you a more complete picture into how your body deals with efforts.

Blood Lactate Test

The curve here is showing the accumulated blood lactate levels at progressively increasing power levels. From this we can determine the physiological level at which the body is switching from predominately aerobic to predominately anaerobic (as indicated by LT2).

The shape of the curve, and the right hand peak are also interesting and tell us something about the profile of ride.

Flat Curve

A flatter curve leading to into and through LT2 can indicate the rider has a reasonable aerobic system but not much of a tipping point (potentially indicating a slightly under-trained athlete).

The rider might not have a good ability to clear blood lactate and prolonged efforts below FTP would steadily increase blood lactate until the rider can no longer hold an effort, even below FTP.

In our example above this rider would not be able to hold FTP in the second or third hour of a ride.

Steep Curve

A steep incline leading to and through LT2 would indicate the rider has a greater aerobic system and ability to clear blood lactate before a more sudden increase (potentially indicating a well trained athlete).

In our example this rider would be able to ride at FTP later into the ride. The rider’s body would be effectively clearing blood lactate at higher relative power to their FTP.


The higher peak on the right can indicate the rider’s ability to sustain a very high level of anaerobic output.

Where to get tested?

I have a limited number of places available for blood lactate testing in December 2018 and January 2019.

Testing slots will be available on Saturday and Sunday between Midday and 3 pm. 

The test will take roughly 60 minutes to complete. 

You will need to bring your bike, a water bottle, your cycling shoes and your cycling shorts. Please contact me if you would like to schedule a test.

The test is carried out on a turbo trainer and your results will be available immediately after the test is complete. 

For other testing centres in Singapore please have a look at the below links.

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