The 20-minute time trial test was developed by coach Hunter Allen, in collaboration with exercise physiologists Andrew Coggan and Stephen McGregor, as a power testing protocol.
The field test can be used to collect data for power and/or heart rate for endurance activities that include running, cycling, cross country skiing, and uphill skimo (swimming uses a different test).
The test can also work for pace, but see the section on using race results for another option for finding running pace and the section on the swimming time trial for finding swimming pace.
Time Trial Protocol
This is a solo time trial to do on your own, not with training partners. You should go into the test rested, not after a hard training day. Find a course for this time trial that you can return to throughout your training to compare results over time. The course can be flat or on a slight grade, but avoid a course with rolling hills. Each time you do the time trial, use a consistent warmup protocol, as described below.
The objective is to perform a 5-minute all-out effort and then a 20-minute time trial at the fastest effort you feel you can consistently maintain for that duration without slowing down. Avoid starting out too fast and then slowing. You want a consistent effort over the 20 minutes.
Warm up for 15-20 minutes at an easy pace. For cycling, do 3 x 1-minute of fast pedaling. For running or other activities, do several striders or pickups. Follow this by another 5 minutes at an easy pace.
The test begins with a 5-minute all-out effort at the maximum effort you can maintain for the full 5 minutes. Start fast and hold it, but avoid starting so fast that you can’t maintain the effort. The purpose of this 5-minute effort is to prime you for the 20-minute time trial and capture additional data. So, record the data from this 5-minute interval.
Recover from the 5-minute effort with 10 minutes at an easy pace.
Then start the 20-minute time trial. Start the time trial at the fastest pace you feel you can consistently maintain for the full 20 minutes. This means going out fast, but not so fast that you’ll need to slow. The best time trial results come from a consistent, hard effort across the full 20 minutes.
After you’re done, warm down for 10-20 minutes. When you get home, upload the workout to your TrainingPeaks training log. In your post-workout comments, record the conditions (temperature, wind, etc.) and other contextual factors that impacted how you felt (sleep, eating, etc.).
Interpreting the Results for Power (FTPw)
Take your average power over the 20-minute time trial and multiply by .95.
Since the power put out over the shorter 20-minute time trial is typically greater than what you could maintain for an hour, the general rule is to take 95% of your average power to estimate your FTPw. This is a general rule, so you may need to play with this a bit as you gain experience interpreting the results.
For example, if your average power for a 20-minute cycling time trial is 305 watts; then multiply 305 by .95 to get 290 watts. This is your FTPw for cycling.
Once you know your FTPw for the given activity, go to the section, “Setting Your Power Zones,” to use that number to set your power zones.
Interpreting the Results for Heart Rate (LTHR)
Finding your LTHR is the same as finding your FTPw.
Take your average heart rate over the 20-minute time trial and multiply by .95.
Since the average heart rate over the shorter 20-minute time trial is typically greater than what you could maintain for an hour, the general rule is to take 95% of your average heart rate to estimate your LTHR. This is a general rule, so you may need to play with this a bit as you gain experience interpreting the results.
For example, if your average heart rate for a 20-minute running time trial is 170 beats per minute; then multiply 170 by .95 to get 162. This is your LTHR for running.
Once you know your LTHR for the given activity, go to the section, “Setting Your Heart Rate Zones,” to use that number to set your heart rate zones.
Assessing Test Quality
The test doesn’t need to be perfect, but it will provide the best results when the output over the 20 minutes is consistent. A graph that shows large spikes in power or heart rate near the beginning and end with a drop in the middle is a sign of an inconsistent test. Similarly, a graph that shows a gradual downhill slide in power or heart rate is a sign of an inconsistent test.
The more practice you gain with the test, the more consistent you’ll be. Remember, the point of the 20-minute time trial is that you can repeat it frequently throughout your training year. So, if you post an inconsistent test, don’t sweat it. Just work to make it more consistent next time.
Adjusting the Protocol & Threshold Values
The protocol for this test was originally devised for cycling. In that situation, doing the 5-minute all-out pre-test before the 20-minute time trial effort makes sense.
If you use this test for running, you may want to modify the 5-minute pre-test. Instead of a full 5 minutes at max effort, do your usual pre-race routine with striders plus some shorter intervals to raise your heart rate. Then ramp up your pace to the time trial effort with a flying start as you launch into the main 20-minute time trial.
This should allow you to post results for the 20-minute time trial that are close to a race-level effort, allowing you to multiply the average heart rate and average power by .95 to arrive at your threshold values.
Also keep in mind that the 95% general rule is just that — a general rule — and not a rigid equation. Adjust the percentage points up or down as needed based on your experience and individual circumstances for the 20-minute time trial to estimate your threshold values.