What is Four-Dimensional Power™?


Training apps that base power targets only on your FTP are just guessing at what you’re capable of above threshold. Not The Sufferfest. We use four key metrics—Neuromuscular Power, Anaerobic Capacity, Maximal Aerobic Power and Functional Threshold Power—to create your complete power profile. We then generate personalized power targets for all of your workouts, giving you exactly the training stimulus you need to get faster. Those other apps don’t know you like 4DP™ does.

Read the 4DP™ FAQ


4DP™: Four Does More

Why is FTP, which only measures your aerobic power, an inadequate measure of your fitness? Because cycling isn’t just about long, sustained efforts. It’s about attacks, surges, sprints and breakaways. It’s about being able to recover and hit it again. That’s why our Four-Dimensional Power™ profile captures your performance across all four of your key energy systems:



Neuromuscular Power is pure sprinting ability.
(5-second power)



Anaerobic Capacity is for short, sharp efforts.
(1-minute power)



Maximal Aerobic Power is sustained power over a few minutes at VO2 max.
(5-minute power)



Functional Threshold Power measures endurance fitness.
(20-minute power)

You are more than your FTP

Functional Threshold Power (FTP) has been *the* metric used by cyclists to set training zones and power targets. But FTP only measures aerobic capacity—your ability to put down power during long, sustained efforts.

FTP doesn’t tell you how well you can sprint, or deliver repeated attacks, or tackle short, steep climbs at maximum effort. FTP is a poor predictor of your ability to generate power above threshold. Training apps that only use FTP to set power targets are making assumptions about what you’re capable of, and what targets you need to hit to get faster.

Reference Metrics for Workouts

Platform NMP (Neuromuscular) AC (Anaerobic) MAP (Maximal aerobic) Functional Threshold
Other training programs
NMP (Neuromuscular)
AC (Anaerobic)
MAP (Maximal aerobic)
FTP (Functional threshold)

Take two cyclists: Both have an FTP of 250 W. Other cycling apps will give both riders the same target for sprint efforts based on a simple percentage of their FTP, typically 180% or 450 W. What those apps don’t know is that Rider A has a maximum sprint power of 1,150 W, while Rider B has a maximum sprint power of 547 W. The result? Rider A will find that 450 W target far too easy—and fail to get any training benefit—while Rider B will find that target nearly impossible to hit and be unable to finish the workout. Consider the example below:

Rider - A

NMP: 1,150 W

AC: 462 W

MAP: 320 W

FTP: 250 W

Rider - B

NMP: 547 W

AC: 332 W

MAP: 295 W

FTP: 250 W

  • Rider A Targets set by 4DP™.
  • Rider B targets set by 4DP™.
  • Rider A & B targets set by FTP alone.

Personalized Power Targets to Match Your Unique Profile

What makes training with Four-Dimensional Power™ so powerful is the unprecedented level of workout precision and personalization. The Sufferfest app will tailor the power targets in all of your workouts to match your unique 4DP™ profile. Different kinds of efforts will reference the appropriate metric, whether that’s Neuromuscular, Anaerobic, Maximal Aerobic, or Threshold Power. You’ll work at the exact intensity necessary to get stronger, faster, and more powerful, without wasting a single pedal stroke. Say goodbye to cookie cutter, FTP-based workouts that don’t know you. Say hello to effective, personalized 4DP™ workouts. Have more questions about 4DP? The answers are here.

Find Your Hidden Power

Not only does your 4DP™ profile tell us what you can do, it also tells us what kind of rider you are. 4DP™ will reveal your hidden power and assign you one of six Rider Types, allowing you to better focus your training:

We’ll also make specific workout recommendations to both develop your strengths and address your weaknesses. No other cycling training app can do that.

The Sports Science of 4DP™

More than a year in the making, Four-Dimensional Power™ was developed in partnership with the sports scientists at APEX Coaching and Consulting in Boulder, Colorado. APEX has built a global reputation training the best of the best, including professional cyclists, Olympic triathletes, and multiple world champions. APEX founder Neal Henderson has known for years that FTP alone isn’t enough to design workouts that work. His research with hundreds of athletes both at APEX and at the Boulder Center for Sports Medicine showed that conventional FTP tests weren’t effective in predicting what an athlete was capable of, especially above threshold. To solve this shortcoming, he developed a comprehensive fitness assessment that gives a complete picture of how effectively an athlete produces power across a range of efforts.


We worked with Neal and APEX Senior Coach Mac Cassin to adapt the same fitness assessment they use with their athletes to create the Full Frontal fitness test. In addition to measuring the four key ways of producing power, Full Frontal also uses known variations in human performance to validate your results. We know whether you nailed the test, were holding back, or might have to do it again.

All of the workouts in The Sufferfest library were analyzed to map every interval to the appropriate 4DP™ metric. This wasn’t simply a matter of setting sprints to Neuromuscular Power or VO2 efforts to Maximal Aerobic Power, but involved looking at each effort’s duration, where it occurs in the workout, and what efforts follow it.

The result is the most sophisticated cycling training app in the world. Don’t guess with FTP - train with the precision of 4DP™. Learn more about 4DP here.

Only From The Sufferfest

With the release of Four-Dimension Power, The Sufferfest has taken the same comprehensive fitness testing and personalized power target mapping used by the pros and made it available to you. No other training app gives you this kind of individually-optimized training. No other app gives you sessions this effective. Stop wasting time on workouts that don’t work. Go beyond your threshold and take your fitness to a new dimension with Four-Dimensional Power™.

Try the sufferfest for free

One subscription works across Windows, Mac, iPad and iPhone devices. Try it for free for 7 days. Cancel easily at any time. If you continue, it’s just $10 USD/month or $99 USD/year.

That's it. No games. Just getting faster.