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.
| 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
When doing a 20 mins threshold test, where should my hr be? Just done one and followed watt bike programme but hr maxed at only 157 BPM ! Should I be nearing max hr towards end of test??
Hi Bryan, the difference between your max heart rate and threashold heart rate will vary, but by definition your max HR will only be theoretically achieved with a long warmup, increasing ramp-like effort over 10-15 minutes and then a final all out high intensity/high effort burst for 30 seconds or so. Coaches & physicians do not often (if ever) recommend actually trying to find your Max as it can be high risk of injury. however you can guage your max by the highest HR you have seen on hard efforts.
A threshold effort in contrast should be done at a lower intensity than your max…you can only hold your max for 10-30 seconds…threshold you can hold for an hour.
The distance between your threshold HR and max HR will vary with your age, fitness and the type of training you do, there is no correct number for everyone. If you did the watt bike test and your HR maxed out at 157 then your threshold HR is likely even lower than 157, and that maxHR for the test should be below your otherwise observed or tested max HR.
This is a case of “it is what it is”…there is no correct number.
If you’re skeptical of the nubmer and think it is too low, then rest up, be sure you are well hydrated and nourished and repeat the test. Try to keep as many variables as you can the same including your breakfast, your hydration, your warmup etc. With better fitness your threshold HR may actually go down as your power output goes up. again there is no correct threshold HR, it is what it is!
No you should not hit your max HR during the test. How close you come to it depends on a lot of factors including your age, your recent training and your genetic “gifts”. There is no right or wrong but it does help to do the test often enough that you have a sense of if you’re going hard enough. If you think you should have gone harder you may see your HR lift at the end of the test. Next time yo do the test warmup well, try to hit that HR during warmup, then recover and try the test starting slightly harder.
Hi,
I have come across this article on the field test for LTHR. I have done a similar test but followed the Joe Friel method of calculation. After obtaining an average HR for 20 minute TT effort, I then calculated my heart rate zones. However, there was a significant difference between your calculation above the Friel one in that he did not use a 95% figure of my av heart rate. Now if I use a 95% of the av HR figure my zones come out quite different. I think I can see the reason you say 95% of my av HR but cann you explian the reasoning to me and why would Friel not advise using 95%?
Thanks
Tim
I can’t say why Friel would not use 95% average, but I can explain why I do. Everyone has different percentages of fast and slow twitch fibers, different training history and different levels of motivation, fueling and recovery on any particular day. Doing a 20 minute time trial uses both aerobic (slow twitch) and anaerobic (fast twitch) fibers. In trying to determine LTHR, true lactate threshold occurs at a lower intensity level than a 20 minute time trial. So taking 95% of the value helps to account for that. In reality, some people will just have a bad day, so a lower %age is appropraite; some people may have a very low anaerobic capacity, so a higher percentage is appropriate. Every test like this is simply an attempt at an approximation of your LTHR…even when lactate is being drawn during the test, the tester is trying to approximate the point where the threshold lies. There are so many different definitions of “LTHR”, or “FTP” or “Anaerobic Threshold” or “ventilatory threshold” that are all very very very close to the same physiologic point, that it matters less which equation you use, and matters more which one you use consistently. Hope that helps.