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Blood Lactate Threshold Testing FAQ

What does it mean to have your blood lactate measured?

  • Exercise physiology testing is used to allow exercise specialists to prescribe individualized exercise intensity.
  • Work within the human body is accomplished three ways, via mechanical means (i.e. muscle contractions), transport (i.e. transfer of substances between cells), and chemically (i.e. synthesis of cellular molecules). To do this work the body needs fuel.
  • The body receives energy from the food we eat; however it’s not a direct transaction. The food, or fuel, must be converted into a currency the body can use. The human body’s currency of choice is a compound called adenosine triphosphate, or more commonly known as ATP. This power-packed molecule fuels all of the body’s processes that require energy.
  • During rest or low intensity exercise, our body takes in sufficient amounts of oxygen to manufacture APT without the build-up of lactate; however, during high intensity exercise lactate accumulates. Lactate is “the burn” you feel in your legs while running uphill for example. When we decrease our exercise intensity, when the ATP demand is lowered, our body can catch-up and reuse that build-up of lactate to make additional ATP.
  • Because lactate accumulates at a rate that correlates to exercise intensity, exercise physiologists can measure blood lactate levels as a way to gage how hard your body is working and at what point lactate starts to accumulate.
  • By training in prescribed “zones” or at prescribed “metabolic intensities”, you can improve your body’s efficiency in terms of up taking and using oxygen, and in turn manufacturing ATP. Elite endurance athletes, for example, are able to continue yielding ATP at very high exercise intensities before lactate begins to building up and decreasing intensity is required.

So how do I know when I am close to or at my lactate threshold when I am running or on the bike?

  • Because it is not practical to directly measure your blood lactate level when you are out on the road for a ride, physiologists have come up with an indirect way to measure intensity – heart rate monitors & power meters!
  • When you are undergoing a blood lactate test, your physiologist will have your wear a heart rate monitor or use your bike’s power meter. At specific time intervals, your blood lactate level is measured and your correlating heart rate or power output is recorded. After your test, the data is analyzed by the physiologist, and you will be given heart rate training zones or power outputs that correlate with blood lactate accumulation.
  • When you are out for your run or riding your bike, you can gage your metabolic intensity by the numbers on your heart rate monitor watch or bike power meter.
What is the benefit of working in different metabolic or heart rate zones?
  • Aside from your blood lactate threshold, there are also other key points along the blood lactate curve that are useful for training effectively.
  • At different points of exercise intensity, your body breaks down different types of nutrients. Fat, for example, is energy dense and it takes more work to break it down. Your body will choose to break down the fat you have consumed when activity intensity is low (i.e. rest, Zone 1, & Zone 2).
  • When you are working at higher intensities (above your lactate threshold), your body will primarily break down carbohydrate (i.e. sugar; Zone 3, Zone 4, Zone 5, Zone 6).
  • People with a weight loss goal benefit from exercising in Zone 2, the “Fat Burning Zone” – the exercise intensity when their body is able to break down fat in it’s quest to manufacture ATP
  • As you exercise more, your body becomes efficient and your low intensity Zone 2 run or ride will become faster and faster.
My friend and I run about the same speed, can I use their heart rate training zones?
  • Using your friend’s heart rate zones likely won’t do you any good. Heart rate and blood lactate clearance are very specific to age, gender, heart muscle strength, blood vessel resistance and elasticity, and time spent training at specific intensities.
  • The most accurate way to determine your training zones is to consult with a certified exercise physiologist and collect the data specific to your body.
How do I get my blood lactate levels measured?
  • At KSL we conduct exercise physiology tests during individual appointment times. If you would like to book an assessment with one of our physiologists, please e-mail us at
  • Testing sessions last approximately 2-hours and require that you follow a few guidelines in the hours leading up to testing. Please CLICK HERE to download KSL’s Pre-Testing Forms.
What is involved in the blood lactate test?
  • The graded exercise test involves running on a treadmill or cycling on a stationary bike at increasing workloads. (You can ride a stationary bike at the lab or bring your own bike and mount it to one of our CompuTrainers ™.)
  • During specified intervals, heart rate or power output is recorded and blood lactate is measured by sampling a trace amount of blood from the fingertip.
  • Information collected is analyzed and used to determine optimal heart rate training zones. After your testing session, you will have a consultation with the physiologist to go through the results and learn how to apply them to your training.

What should I bring on test day?

  • A list of what to bring, along with pre-testing guidelines, can be found HERE.

More Questions?

This FAQ is meant to give some basic information. If you have more questions, want more details or want to book your blood lactate test and start training smarter, get in touch!

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