SMART Intervals – Knowledgebase

SMART Intervals are dynamically adjusted workout intervals that use your unique Fitness Signature and real-time fatigue (MPA) to set power targets, creating dynamic intervals for precise, personalized training. They adapt automatically as your fitness changes, ensuring optimal difficulty and stimulus, and require a Xert-compatible workout player.

Summary Generated by AI

Definition

SMART Intervals are dynamically adjusted workout intervals that respond to your fatigue in real time and/or are based on your unique fitness signature.

Unlike traditional fixed-power intervals, SMART Intervals continuously adapt based on your Fitness Signature and Maximum Power Available (MPA).

What It Means

Traditional workouts prescribe fixed targets (e.g., 110% FTP for 5 minutes).

SMART Intervals prescribe targets based on:

XSS Rate (XSSR)
Target MPA
Or fitness signature-specific efforts (e.g., 5 MMP, % Lower Threshold Power, etc.)

Because Xert accounts for fatigue, the required power may rise or fall during the interval. This creates Xert’s iconic curvilinear intervals, rather than perfectly flat ones. These intervals cannot be replicated anywhere else and they make for a fun & unique workout experience.

**Example: SMART – Closer 150.** Notice the slightly curved, “fast-start” shape of these intervals. Using XSS Rate (XSSR), Xert delivers a higher power at the start of the interval to rapidly stress the High system, then gradually tapers the target towards Threshold as fatigue accumulates. This makes the intervals efficient, while still being achievable.

How SMART Intervals Work

SMART Intervals use your Fitness Signature to calculate power targets second-by-second.

This allows workouts to:

Scale up and down automatically as your fitness changes
Adjust an interval based on fatigue in real time as you do the workout
Deliver very precise strain to the intended energy systems
Maintain the correct difficulty without over- or under-shooting

Workouts remain relevant throughout the season & to each athlete, so there is no need to create several iterations of the same workouts to accommodate different athletes.

Why They Matter

SMART Intervals:

Reduce the need for frequent re-testing
Ensure you reach the intended training stimulus
Prevent workouts from becoming too easy or too hard
Precisely target Low, High, or Peak systems

They allow training to be fatigue-aware, not just power-based.

Where They Work

SMART Intervals require a Xert-compatible workout player:

Xert EBC (iOS / Android)
Xert Workout Player (Garmin Connect IQ)

Note: Because they rely on real-time MPA calculations, Xert's advanced SMART intervals & curved intervals cannot be exported to other platforms. Instead, they'll be exported as fixed intervals or ramps.

Related Terms

MPA
XSS Rate (XSSR)
Fitness Signature
Focus Duration
Breakthrough