Power Curve (Power-Duration Curve / PDC) – Knowledgebase

The Power Curve, or Power-Duration Curve (PDC), models the maximum average power you can sustain for various durations, assuming a fresh start and steady effort until failure. Xert calculates this using your Fitness Signature and MPA, offering a theoretical rather than historical bests-based curve, reflecting your combined energy systems.

Summary Generated by AI

Definition

The Power Curve - also called the Power-Duration Curve (PDC) - describes the relationship between how long you can sustain a given power output. It represents your maximum average power across different durations, assuming you start fresh, you ride at steady power, and you continue until failure.

The point where you can no longer sustain that power is called a point-of-failure.

What It Represents

The Power Curve answers a simple question:

“How much power can I sustain for a given amount of time?”

Short durations correspond to higher power. Long durations correspond to lower power.

The Xert Power Duration Curve represents your modeled fresh-to-failure performance across durations. It is calculated from your Fitness Signature and visualizes your theoretical maximum power for a given time.

Your Power Curve reflects the combined behaviour of your three energy systems:

Peak Power (PP)
High-Intensity Energy (HIE)
Threshold Power (TP)

In Xert, your Fitness Signature defines your Power Curve.

Note: Many of Xert’s SMART workouts use your Power Curve to determine interval intensity. For example, an interval prescribed as 5 MMP means the effort should be performed at your modeled 5min Mean Maximal Power (MMP). As your Fitness Signature changes over time, these interval targets automatically update - ensuring your workouts remain aligned with your current fitness level throughout the season.

How Xert Calculates the Power Curve

Xert uses MPA (Maximum Power Available) to model your Power Curve. For any steady power output, Xert calculates how long it would take for MPA to decline until MPA reaches your steady power output, which represents a point of failure.

This allows Xert to determine:

The duration you can sustain a given power
Or the power you can sustain for a given duration

Importantly this can be done as your MPA decreases & recovers throughout your rides!

Some platforms build a power curve using Mean Maximal Power (MMP) - your highest recorded average power for each duration. Xert’s Power Curve is modeled from your Fitness Signature rather than relying solely on historical bests.

As a result, your Xert curve may sometimes appear higher than your recent recorded efforts. Learn more in: FAQ: Why Is My Xert Power Curve Higher Than My Recorded Bests?

Where You’ll See It

In Activity Details, under Power Duration tab
On the Power Curve page

Common Misunderstandings

The Power Curve is not just historical bests. It represents modeled maximum possible performance.
It assumes fresh-to-failure efforts. Most real-world data does not meet these conditions.

Related Terms