EndoGusto builds your athletes' training zones from a small set of threshold values: FTP, LTHR, LT Pace, T-pace, and RPE. Each one anchors the zones for a sport, and together they decide how accurately EndoGusto scores training load.
This guide explains what each training threshold term means and which sport it applies to.
Training Thresholds at a Glance
Term | Full name | Sport | What it measures |
LT Pace | Pace at Lactate Threshold | Running | Running pace at threshold |
LTHR | Heart Rate at Lactate Threshold (HR at LT) | Running, Cycling | Heart rate at threshold |
FTP | Functional Threshold Power | Cycling | Power at threshold |
T-pace | Threshold Pace (swim) | Swimming | Swim pace at threshold |
CSS | Critical Swim Speed | Swimming | A test-based estimate of swim threshold pace |
RPE | Rating of Perceived Exertion | All sports | How hard the effort feels |
What Lactate Threshold Means
Most of these terms refer to the lactate threshold, also called the anaerobic threshold. It is the intensity of exercise at which lactate begins to accumulate in the blood faster than the body can remove it.
Below it, an athlete can hold an effort for a long time. Above it, fatigue builds quickly. That makes it the most useful single anchor for setting training zones in every sport.
Running and Cycling Threshold Terms
LT Pace (Pace at LT)
LT Pace is the running pace an athlete can hold at their lactate threshold. EndoGusto reads it first when it calculates running zones and ECOs, because pace measures the work the athlete actually produced.
LTHR (HR at LT)
LTHR is the heart rate that corresponds to an athlete's lactate threshold. EndoGusto uses it for heart rate zones in running and cycling, and as the fallback for ECOs when an activity has no pace or power data.
FTP (Functional Threshold Power)
FTP is the highest average power a cyclist can sustain for about one hour, measured in watts. It anchors power-based cycling zones and is the first signal EndoGusto reads for rides with a power meter.
Swimming Threshold Terms
T-pace (Threshold Pace)
T-pace is the swimming equivalent of LT Pace in running or FTP in cycling. Instead of heart rate or power, it is based on swim pace, usually expressed per 100 meters.
CSS (Critical Swim Speed)
CSS is a common way to estimate an athlete's swim threshold pace from two time trials, typically a 400 m and a 200 m. If your athlete has recent pool times for both distances, CSS gives you a quick, repeatable threshold value.
RPE (Rating of Perceived Exertion)
RPE describes how hard an effort feels to the athlete. It works in every sport and needs no device, which makes it useful for athletes without a heart rate monitor, power meter, or GPS.
In EndoGusto, you can prescribe workout steps by RPE in the Workout Builder, and ECOs uses RPE as the final fallback when an activity has no pace, power, or heart rate data.
Where to Set These Values
Set each athlete's threshold values on their individual Training Zones tab. EndoGusto recalculates their zones from the new values, and more accurate thresholds give more accurate ECOs scores. See How to Change an Athlete's Training Zones for the steps.
To learn how these thresholds feed into training load, read Understanding ECOs: How EndoGusto Measures Training Load.
Tips for Coaches
Retest every 6 to 8 weeks in a build phase. Thresholds move fastest when training is consistent, and stale values put every zone-based workout in the wrong range.
Set a pace or power threshold, not only heart rate. ECOs reads pace and power first, so an athlete with only LTHR set gets a less precise load score.
Use RPE for athletes without devices. Prescribing by RPE keeps their sessions structured and still gives them an ECOs score.
Keep swim thresholds pool-based. Open water conditions vary too much to set a reliable T-pace or CSS.
For Athletes
Your coach sets these values to build your training zones, so your workouts target the right intensity. If you complete a test or race that shows a new threshold, let your coach know so they can update your zones.
Need help? Open the chat bubble in the bottom corner of this page, or email us at [email protected].