When we engage in training, our body undergoes specific adaptations in the hope of improving the body’s efficiency and capacity. Athletes train in specific zones to apply a measured amount of intensity to improve targeted areas of their physiology. When training with power on the bike, we use:

  1. Functional Threshold Power (FTP) to establish training zones, and
  2. the athlete’s metabolic fitness.

It’s hard for many athletes to know when to bump up or bump down their FTP used in determining power training zones. Many factors can impact fluctuations in your power training zones, such as improved fitness, injury, a busy work schedule, or time away from training. One mistake that many athletes make is establishing power training zones and never adjusting them to match their current state of fitness. 

The traditional method of establishing your power-based training zones is to complete a functional threshold power test (FTP). When Dr. Andy Coggan developed the FTP performance metrics, he originally defined FTP as “the highest power a rider can maintain in a quasi-study state without fatiguing for approximately one hour.” Many of the metrics in Training Peaks, such as TSS, are calculated using FTP at one hour in the formula. Within the past few years, Dr. Coggan has redefined the definition of FTP to “the highest power a rider can maintain in a quasi-study state without fatiguing” and included the metric of Time to Exhaustion (TTE). Dr. Coggan defines TTE as “the maximum duration for which a power equal to model-derived Functional Threshold Power can be maintained. 

When Training and Racing with a Power Meter (Allen & Coggan, 2010) was published, one testing protocol established was the 20-minute test. The test is based on 20 minutes to produce the highest average wattage over the entire period minus 5%. I predominantly use the 20 min test for athletes without past training experience or other underlying issues such as joint health. I currently use a testing protocol starting with a 30-minute test and often extending to 60 minutes using the highest average wattage over the entire period to establish FTP. I will set the duration of the test using data molding available in Training Peaks WKO that generally correlates to the athlete’s TTE, giving me the data to understand better the athlete’s sustained power output and resistance to fatigue. 

We now have two essential metrics we can use to formulate our training. For many athletes improving TTE shows more significant performance benefits than a higher FTP number alone. When I see improvements in an athlete’s TTE at threshold, we often see a correlation to longer durations of sustained power outputs in other power zones. I regularly prescribe workouts with a focus on extending TTE to improve fatigue resistance. If an athlete has a current TTE of 37 minutes, a workout may be specified at 40 -45 minutes @ 95 to 105% of their current FTP. However, a gain of thirty seconds should be considered beneficial.  Below is a graph of an athlete’s Power duration curve from Training Peaks WKO. We can see the point of sustained degradation or no longer holding their FTP at the thirty-seven-minute mark. Using the TTE model, if you cannot hold your current FTP for 30 minutes, then the chances are your FTP is set too high. Conversely, if you can hold your current FTP for over an hour, your FTP is probably set to low.

Back to that common mistake of many athletes make not updating their power training zones regularly. What is meant by regular is every thirty days or after a significant event that limits training time like an injury or time away from the sport. We can conduct FTP tests in several ways outside of formal testing.

Many athletes have an aversion to testing, so a few alternatives are a local  TT or a local crit or cyclocross race. Also, there is no rule against group FTP tests; get a group of friends or team together and do a TT and use the results to set your FTP and TTE.  You can also go for a hard ride at the highest power you can maintain for 30 to 60 minutes. Often the results will match your current FTP or perhaps even be higher, but if your FTP has fallen, then repeat the effort in a week or two and adjust your zones accordingly.

If your FTP has dropped, the cause could be the result of many reasons, don’t panic. You may need to change your training plan, or in some cases, it may be time for a good rest. Whatever the outcome, don’t let your ego dictate your power training zones. Test regularly and use FTP and TTE as benchmarks to gauge your current state of fitness. Hard work does pay off. 

Coach Geroge Epley has a passion for knowledge and believes it’s the key to maximizing your potential. He keeps abreast of the latest scientific studies, always trying to find more efficient and validated means of coaching his athletes. Knowledge in the form of communication is just as important. The more he know about his athletes and the sooner he know of changes in circumstances, lifestyle or training, the greater resource he can be.

Coach George’s Certifications:

  • USA Triathlon Level II Certified Coach
  • USA Triathlon Youth & Junior Elite Certified
  • USA Cycling Elite Level 1 Coach
  • USA Cycling Cyclocross Certified
  • ACSM – Certified Personal Trainer
  • MBSC – Certified Functional Strength Coach
  • Training Peaks University Certified
  • Training Peaks WKO4 Certified

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