January 26, 2021
The Functional Threshold Pace (FTPa) field test is useful for determining training zones and tracking fitness progression. Here’s how to do it.
If you want a way, outside of racing, to track improvements in your running performance, Functional Threshold Pace (FTPa) field testing could be just what you’re looking for.
Besides providing a way to track your fitness progression, the test’s output also allows you to calculate training zones specific to your current level of fitness.
Simply put, FTPa is the best average pace you can currently sustain for around 60 minutes. It’s a measure of both your speed and endurance, and it provides useful feedback about your current fitness across all distances from 5km to marathon.
Knowing your threshold running pace is valuable for three reasons:
There are three common methods that runners and triathletes use to determine their FTPa.
Lactate testing is my preferred method, but not everyone has access to a lab or wishes to invest the money. The 60-minute test is arguably the next most accurate behind the lactate test, but it puts a tremendous load on your body. It can interfere significantly with your training due to the recovery needed post-test.
The final option is the 20-minute test, my preference when lactate testing is not an option, and that’s the focus of the remainder of this article.
Before deciding when to run an FTPa field test, you need to consider certain factors to maximise your run and get the most reliable result to establish your training zones.
Below are the factors that you have control over, and that can influence your test. Please consider each carefully and aim to keep things as consistent as possible between tests.
The 20-minute test is challenging and puts a tremendous strain on your body. Do not attempt this test if you are ill or suffering from any form of niggle. You want to be in good condition when you run this test.
Depending on where you live, we recommend that you conduct this test early morning or late evening when it is cooler. That way, you can avoid the added stress of heat and humidity.
Make sure you adequately hydrate before the test. If you are conducting the test in the morning, you will wake from sleep dehydrated. Preload with sodium (300-500mg) to assist your cardiovascular system 30-minutes before you start. The same applies if you run late in the evening. Hydrate well throughout the day and preload with added sodium 30-minutes before you start your run.
When conducting this test, you must run on a flat surface. Research a route near you beforehand where you know there is little to no change in elevation. The test must be continuous and uninterrupted, so plan a course that does not have traffic lights in your way. Stay away from tall buildings to avoid GPS and pace errors, because they can cause interference with your monitor that could put your results at risk. If you run on a treadmill, set the gradient to 1.5%.
Getting enough sleep is paramount when it comes to assisting your body. Aim for 7+ hours the night before the test. A lack of sleep will force your body to work harder than usual to manage the test’s applied stress. This fatigue can lead to elevated heart rate, reduced output, and a false result.
We strongly encourage you to use a heart rate strap for this test. Straps provide more accurate and reliable measurements and increase the validity of your results.
If that’s not possible, use your wrist-based monitor, but ensure it’s tight and reading as accurately as possible before you begin.
Upon completing the test, take your average heart rate and pace of the entire 20-minute time trial. Subtracting 5% from each number will give you an approximation of your lactate threshold pace and heart rate.
With lactate threshold pace and heart rate established, you can plug those numbers into an online calculator to determine your training zones.
You can also compare your results to past results or races to gauge how your fitness is progressing over time.
Testing every 8 – 10-weeks is a good guideline, although you should not be dogmatic and should set your testing schedule to suit your goals and current physical condition.