Glossary: FTP, CSS, threshold pace

FTP, Functional Threshold Power (cycling)

The highest average power in watts you can sustain for roughly an hour on the bike. FTP is the anchor for cycling training zones, race pacing, and Load computation.

Common ways to determine FTP:

• 20 minute test, 95 percent rule: ride 20 minutes flat out after a thorough warm-up. FTP equals 95 percent of the 20 minute average power.
• Best 1 hour ride or race: if you have a recent flat-out hour on the bike (e.g. a hilly time trial), use that average.
• Ramp test: a graded test that estimates FTP from your point of failure.

Retest FTP every 4 to 8 weeks during a build phase, less often in base.

CSS, Critical Swim Speed

Your best steady swim pace sustainable for roughly 30 minutes in a pool. Used as the swim equivalent of FTP, anchoring swim training zones and pace prescriptions.

Standard CSS test:

• Warm-up.
• 400 m time trial as hard as you can hold pace.
• 5 to 10 min easy.
• 200 m time trial.
• CSS pace per 100 m equals (400 distance minus 200 distance) / (400 time minus 200 time), scaled to a per-100 figure.

Retest every 6 to 12 weeks.

Threshold pace or LT pace (run)

The fastest running pace you can hold for roughly 45 to 60 minutes. Similar to FTP and CSS but for running. Anchors run training zones.

Common ways to determine:

• 10K race result: average pace from a recent 10K is close to threshold.
• 30 minute time trial.
• Lab lactate test for accuracy.

Retest every 8 to 12 weeks, or implied from race results.

Why three different anchors

Each sport has a different limiting system:

• Bike: power is independent of terrain when normalised.
• Swim: pace depends on stroke and drag.
• Run: pace varies with surface, grade, and wind.

A single threshold does not translate cleanly across the three. Each needs its own test.