At the beginning of a new phase of training it is important to get a snapshot of an athlete’s current fitness so you can scale training intensities appropriately. Assessing an athlete’s Functional Threshold Power (FTP) is the most utilized method because FTP testing can be accomplished outside a lab setting. All you need is a power meter or a smart trainer (a heart rate monitor provides useful contextual information, too). Three FTP tests used by coaches, indoor cycling apps, and training analysis tools like Trainingpeaks include: a ramp test, an 8-minute test, and a 20-minute test. Here’s what they are, how to choose and complete a test, and what to do with the results.
What is FTP?
A cyclist’s Functional Threshold Power is the highest average power output a cyclist can maintain for 60 minutes. Although it is not the same thing as lactate threshold, it can be used to predict power at lactate threshold when athletes cannot directly measure blood lactate during a test. From a practical standpoint, it determines the highest amount of work your aerobic system can sustain for prolonged efforts. Your VO2 max, on the other hand, defines your maximum aerobic capacity, or the highest volume of oxygen your body can take in and use.
With a higher FTP a cyclist can produce more power – and hence go faster – during prolonged hard efforts like time trials and hill climbs. A higher FTP also means a cyclist can ride at a moderate pace with less difficulty, like during a group ride or while sitting in the pack during a race.
Increasing a cyclist’s FTP is a priority because it is highly trainable. With focused training, and depending on current fitness, a cyclist may increase FTP by 20-50%. Large improvements are common for relatively inexperienced cyclists. There is a diminishing rate of improvement as FTP approaches power at VO2 max.
FTP and VO2 max
The relationship between FTP and VO2 max is also important. VO2 max is largely controlled by genetics but can improve by about 15% with training. Because FTP is more trainable, there’s an opportunity to increase FTP as a percentage of power at VO2 max. This fractional utilization tells you how much of your maximum aerobic capacity you can use for sustained efforts.
Think of your aerobic system as a warehouse. VO2 max is the total volume of the warehouse and the volume of material in the warehouse is your FTP. To put more material in the warehouse you can raise the ceiling (increase VO2 max) or reduce the empty space (increase fractional utilization). Ideally, an athlete’s goal is to do both.
FTP Testing Methods
Outside of a physiology lab, there are three common methods for assessing a cyclist’s FTP: a ramp test, an 8-minute field test, and a 20-minute field test. They are all effective, but each has its pros and cons and best use cases for individual athletes.
The ramp test incrementally increases resistance or prescribed power output in one-minute stages until you can no longer continue pedaling. Unlike the other tests described in this guide, it is a test to failure. Because they are well suited to smart trainers with ergometer mode, ramp tests are common in apps like Zwift, and Trainerroad. Wahoo SYSTM uses an hour-long test called Full Frontal, which should be completed in Level Mode.
Following a warm up, the ramp test starts at 100 watts and increases by 20 watts each minute. Once the test is complete (you reach the point of failure), the apps use an algorithm to calculate your FTP based on the power output of the final stage and how long you lasted in that stage. The calculation for estimating FTP from the last/best stage of a ramp test was developed by developed by Ric Stern of CycleCoach.com. If you’re doing a ramp test without a smart trainer, record the power output of the final stage of the test. Multiply it by .75 and use the resulting value as your FTP when setting training ranges.
Pros of Ramp Test:
- Doesn’t get really hard until the final minutes. It’s not an easy test, but the hardest part is shorter than with other tests. Because of this, the ramp test requires the shortest post-test recovery time.
- Simpler than pacing a time trial. Athletes who struggle with self-paced maximal efforts benefit from the ergometer-enforced structure.
- As coaches, we find that athletes who are new to structured training often find this test to be the least intimidating.
Cons of Ramp Test:
- May overestimate FTP a bit for athletes with higher anaerobic capacity. They can produce more power during shorter efforts like the ramp test. This could skew the FTP calculation a bit high, but rarely so much that the value is unusable.
- May underestimate FTP a bit for some athletes, too. As with all these tests that multiply a power value by a percentage, there will be individual variation. Your FTP could be 70% of final minute power instead of 75%. The ramp test provides a good starting point, which can be confirmed through subsequent workout performances.
- Is best suited for electronically controlled smart trainers, which not everyone has access to.
Best Use Cases for a Ramp Test
Cyclists who will complete a large portion of their training indoors on a smart trainer are good candidates for ramp testing. FTP test results indoors and outdoors typically exhibit some variation (about 5-10% in either direction). If most of your training is indoors, test indoors using the test best suited to smart trainers.
Ramp tests may also be more accurate for novices because they require less experience with pacing. Cyclists can improve 8-minute and 20-minute power outputs due entirely to learning how to pace time trial efforts.
8-Minute FTP Test
The 8-minute field test was originally created by CTS. Our coaches still utilize this test with many athletes, and you can find it in the Trainerroad app as well. Following a warmup, the test consists of two 8-minute time trials separated by 10 minutes of easy spinning recovery. Detailed instructions can be found here. If using a smart trainer indoors, use slope/resistance mode rather than ergometer mode. CTS Coaches multiply the higher of an athlete’s two average power outputs from the 8-minute efforts by .90 to create CTS Training Intensities. Apps that typically average the two average power outputs, multiply by .90, and use that value as FTP.
CTS developed the 8-minute test because it provides additional information and context to a cyclist’s threshold value. Because the efforts are shorter than a 20- or 60-minute time trial, athletes record average power outputs well above lactate threshold, giving some insight into the athlete’s VO2 max. Two efforts separated by recovery also provides information about the athlete’s ability to recover and repeat hard efforts. Read this article on “Tips for Acing Your Next FTP Test”.
Pros of 8-Minute Test
- Simpler pacing compared to 20-minute test or 60-minute time trial. Maintaining the focus and motivation for a self-paced maximal effort is a learned skill.
- Good for cyclists who may not be ready to complete a high-quality 20-minute time trial.
- For outdoor testing, many cyclists can find an 8-minute stretch of uninterrupted road. A safe and suitable environment for an outdoor 20-minute effort can be hard to find.
- Does not require or utilize ergometer mode on a smart trainer.
- Can be completed indoors or outdoors.
Cons of 8-Minute Test
- May overestimate FTP. As with the ramp test, athletes with higher anaerobic capacity can produce more power during shorter efforts. The conversion factor (multiplying by .9 vs. .95 for 20-minute test and .75 for ramp test) takes this into account, but FTP may a bit high.
- May be too short for highly trained athletes. Athletes with high VO2 max values may be able to sustain power at VO2 max for more than five minutes. Two to four minutes is more typical for moderately trained athletes.
Best Use Cases for 8-Minute Test
CTS recommends the 8-minute test for novice athletes and age-group competitors. The additional information about rate of recovery and repeatability of hard efforts is valuable for developing training plans. A longer, single time trial may be more appropriate for elite, emerging elite, and highly trained age group athletes.
20-Minute FTP Test
Andy Coggan and Hunter Allen coined the term ‘Functional Threshold Power’ and created the 20-minute FTP test. They also authored “Training and Racing with a Power Meter”. The test and associated training zone calculations were featured in early versions of TrainingPeaks and quickly became ubiquitous.
Following a warmup, cyclists simply complete a single 20-minute self-paced time trial at the highest power they can muster. If using an smart trainer indoors, use slope/resistance mode rather than ergometer mode. To calculate FTP, the average power output from the 20-minute test is multiplied by .95.
Pros of the 20-minute FTP Test
- Most accurate correlation with an athlete’s lab-tested lactate threshold power.
- Not as physically or psychologically stressful as a 60-minute time trial.
- Does not require or utilize ergometer mode on a smart trainer.
- Can be completed indoors or outdoors.
Cons of the 20-minute FTP Test
- Average power for a 20-minute time trial depends heavily on an athlete’s pacing skills. This favors experienced and highly trained athletes but may be problematic for novices.
- Although less physically taxing than a 60-minute time trial, this test is a big training effort on its own. That means more rest time beforehand to ensure a quality test, and more post-test recovery time.
- Susceptible to individual variation (like the other tests). FTP value should be confirmed with subsequent threshold workouts. If FTP has been overestimated, threshold training intensities will be set too high. You’ll see that reflected by an inability to complete threshold intervals or a perceived exertion level that’s too high.
Best Use Cases for 20-Minute Test
A 20-minute test is a good choice for almost any cyclist capable of completing a high-quality 20-minute effort. It is the preferred self-paced field test for elite, emerging elite, and highly trained age group competitors. The test is well suited to cyclists experienced with steady-state endurance efforts and events, like time trials, triathlons, and road and gravel races. It’s not that the FTP value is more accurate for these athletes. Rather, they may execute better tests compared to criterium, cyclocross, and MTB competitors (XC and gravity). Either the ramp test or 8-minute test may be better for athletes in shorter events featuring stochastic high intensity.
Using Your FTP Value to Set Training Intensities
A cyclist’s FTP value is used to calculate power zones or ranges that guide the athlete’s training. Although they can be calculated by hand, most training softwares and apps calculate these zones automatically once you choose your preferred training system. In some cases, you can manually input or change the FTP value used in these calculations.
Cyclists need to re-take FTP tests periodically to ensure their training zones reflect their current level of fitness. As you get stronger, your zones must increase so you train hard enough to make more progress. When you lose fitness from time off or an injury, your zones must be lowered so they’re not too hard.
Typically, FTP tests are scheduled after a rest period that follows a focused block of training. That block of training was completed with a certain FTP value. Testing before your next block sets a value that reflects any changes – up or down – from the recent training.
Physiological adaptation to training occurs over the span of several weeks or months, not days. As a result, the shortest period between FTP tests is typically six weeks and can be 2-4 months. Even if you test less frequently, at least two FTP tests are recommended per calendar year.
By Chris Carmichael,
Founder and Head Coach of CTS