Functional Threshold Power: Useful? Or simply too variable?
Dr Andy Coggan and Hunter Allen established the term Functional Threshold Power (FTP) from the idea of combining the concept of Lactate Threshold (without blood extraction) and power data to create a more accessible approach to finding a threshold for cyclists to use for training and monitoring performance.
Threshold provides a balancing point between the physiological energy systems. In the case FTP / Lactate threshold, this is between aerobic and anaerobic known as the Lactate 2nd turn point (LT2) when lactate is produced and accumulates in the blood at a faster rate than it can be removed. It is generally regarded as the highest power a rider can maintain in a quasi-steady state without fatiguing for 1 hour.
Image: Loughborough University, UK
To find your true Functional Threshold Power, the obvious way is to ride as hard as possible for 1 hour, and your average power for that duration will be your FTP.
Realising the many challenges associated with this, (most notably the unpleasantness associated with a 1 hour max effort), Coggan and Allen devised a 20 minute test whereby a subsequent calculation could be made using the average power for the 20 mins to establish your estimated FTP for 1 hour.
For example: 2Omin average power of 280 watts x 0.95 = 266 watts FTP.
Why calculate 95% of average power?
Coggan and Allen found from their research that people were performing their 20 min FTP effort at 5% higher than they could for an actual hour. Therefore, they account for this 5% by subtracting it to determine a closer estimate to the 60 min power you may be able to produce.
How to test?
It is important to go ´all out´ on the 5 min max interval as a means of flushing out your system to decrease overall freshness prior to the 20 min FTP effort.
Testing indoor or outdoor? Does it make a difference?
Yes. It is recommended to test specific to the environment you will mostly train in.
There are some obvious differences between indoor and outdoor but factors such as: type of indoor trainer and the resistance it gives (magnetic, fluid, smart trainer), ventilation, heat, psychological impact of going max for 20 mins in a static situation, can all have a big impact on your final FTP result, when indoors compared to outdoors. The advances in smart trainers and their accuracy of measuring power is now excellent along with a more natural road feel, but if you are using an older trainer – especially magnetic, then there can be very big differences in the Rate of Perceived Exertion (RPE) (normally higher) versus the power readings from a power meter directly mounted on the bike.
This doesn’t mean that outdoors is easier, as it is still a max effort, but many riders tend to prefer testing outdoors as there are more subtle distractions such as just handling the bike, changing scenery, better ventilation etc, to make the time seem like it passes quicker.
As most riders do a mix of indoor and outdoor training, then it is highly recommended to test your FTP and set your training zones specific to each environment.
Are there other factors that can affect FTP results?
There are a few factors to consider in the lead up to a test which can affect your performance such as: nutrition, hydration, sleep, stress, general fatigue, muscle soreness, altitude, and time of day. But the overriding factor can simply fall to how you feel on the day, and if you are psychologically feeling good to do the test.
Max tests are hard, and if your head is not ´in it’ on the day, then this can greatly affect the outcome. If you don’t feel great before the test, then it is best to simply not do it at that time.
Does FTP provide a full picture of a rider’s capabilities?
No. In short, FTP can provide you with an estimated threshold point but essentially tells you nothing about your capabilities above FTP. For example, a rider with high fast twitch muscle ability (sprinter) may have a lower FTP than a rider with high slow twitch muscle (endurance), but the sprinter’s anaerobic sprint power will be much higher than the endurance rider. Therefore, if using the standardised percentages of FTP to set training zones to train a sprinter, then the rider will not be training at power specific to their true potential. The same issue arises for the endurance rider with a high FTP doing anaerobic sprint intervals, they may not be able to hit the numbers prescribed because of the generic percentages being set to FTP.
So a lot of care should be taken when using FTP as your stand alone training metric!
(Table showing Power-Based Training Zones as defined by Dr. Andrew Coggan.)
| Level | Name | Average Power | Average Heart Rate |
| 1 | Active Recovery | <55% | <68 |
| 2 | Endurance | 56-75% | 69-83% |
| 3 | Tempo | 76-90% | 84-94% |
| 4 | Lactate Threshold | 91-105% | 95-105% |
| 5 | VO2 Max | 106-120% | >106% |
| 6 | Anaerobic Capacity | >121% | N/A |
| 7 | Neuromuscular Power |
N/A | N/A |
Is FTP useful or should it be avoided in favour of more exact analysis?
There is no mistaking the fact that there are many variables that can affect the FTP result, plus the lack of accuracy for training prescription above FTP is a huge issue.
But……if you are new to doing tests and training with power, then FTP can serve as a starting point to gaining experience working with power. But as your experience grows and performance increases, then it is important to carry out testing that will provide you with more accurate and reliable data to allow even greater gains to your performance.
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