Cycling Threshold Field Test Protocol

20 Minute Protocol

This is a twenty minute field test protocol used to determine your “threshold power” or “threshold heartrate”.  Knowing your threshold heartrate will help you both plan workouts as well as measure progress in your training.

Field Test Warmup

(Why you should warmup before testing, training and racing, Sample warmups depending on your fitness level)

10 Minutes easy riding in middle chainring, 10 minutes…just easy spinning, get your legs loose, get your mind loose.
30 second spin up to 100 rpms, recover for 2-3 minutes, repeat once…effort should be light to moderate, easy gears.

30 second effort recover 2-3 minutes, repeat once. 5 minutes easy spinning  after that last hard effort and finish within about 5 minutes of the race start.

  • Begin 20 minute effort at maximum sustainable effort.
  • If needed start slightly below what you think you can sustain, but continue increasing effort without going harder than you can sustain for the duration of the test. You should finish knowing you gave it everything you had.
  • Your estimated  Lactate Threshold Heart Rate (LTHR) is 95% of your 20 minute average heart rate for the test.
  • 15 minutes easy cool down.

Now you can do some simple math to determine HR training zones, either relative to your LTHR, or as a percentage. These zones are starting points.  Each test will have some variation as heart rates can vary from day to day depending on several factors. Taking 95% of your 20 minute average HR is just an estimate for your “true” threshold heart rate which could be determined with a 60 minute time trail.

As long as you maintain the same conditions from test to test, the 20 minute test is excellent for maintaining your current heart rate zones and measuring progress from test to test througout the season.  Record in your trianing log your 20 minute heart rate average, the total distance covered for the test and the average speed of the test.

The heart rate is used to determine training zones, and the average speed and distance are used to  measure progress from test to test.


Calculating your Heart Rate Zones
Zone % LTHR Easy Math
Level 1 (Recovery Zone) 0-68% < LTHR – 35 beats
Level 2 (Endurance) 69-83% 25 – 35 beats below LTHR
Level 3 (Tempo) 84-94% 15 beats below LTHR up to LTHR
Level 4 (Threshold) 95-105% Tested LTHR from time trial
Level 5 (VO2)   >106% 5-10 beats above LTHR

Please send comments/corrections to coach AT steelcityendurance DOT com


References:  Training and Racing with a Power Meter, Hunter Allen & Andy Coggen; Dr. Phil Skiba, personal communication