Training load explained: Effort, Power, Fitness, Fatigue and Form

TrainerPlan turns every workout into a single number — how hard it was — and then tracks what those numbers do to you over weeks and months. Five words on the screen carry the whole system: Effort, Power, Fitness, Fatigue and Form.

If you have used another platform

The concepts are the industry-standard ones; only the labels differ. This table is worth keeping in mind while you read the rest:

In TrainerPlan Elsewhere you may know it as Effort TRIMP (heart-rate training load) Power TSS® — Training Stress Score® Fitness CTL (Chronic Training Load) Fatigue ATL (Acute Training Load) Form TSB (Training Stress Balance)

Effort and Power: two ways to score one workout

Effort scores a workout from heart rate. It weighs every minute by how high the heart rate is within the athlete’s heart-rate reserve (between resting and maximum heart rate), so an hour easy scores far less than an hour hard. It works for any sport where you wear a heart-rate strap or watch — running, swimming, rowing, cross-country skiing, the gym.

Power scores a workout from power output instead, which is more precise because it measures work done rather than the body’s response to it. It needs a power meter, and TrainerPlan calculates it for cycling and rowing workouts.

You choose which one drives the Performance chart with its Source setting (under Chart settings on the chart, on the athlete’s Dashboard): Effort, Power, or Power & Effort combined. Most coaches leave it on the combined option, which uses power where it exists and falls back to heart rate everywhere else — so a cyclist’s turbo session and their weekend run both count.

Set your thresholds first, or the numbers mean nothing

Both scores are relative to your athlete. Effort needs the athlete’s maximum and resting heart rate (the combined option also uses threshold heart rate); Power needs an FTP. Without maximum and resting heart rate, Effort stays at zero and the charts stay flat no matter how much training goes in; without an FTP, TrainerPlan assumes 220 W and the Power numbers are off. If your Fitness line is a flat zero, check those values first.

TrainerPlan can also detect threshold changes for you from synced workouts and offer a one-click update, so the scale keeps up as the athlete gets fitter.

Fitness, Fatigue and Form: what the training does to you

Once every workout has a score, the chart tracks three running averages of those scores.

• Fitness is a 42-day weighted average. It moves slowly, because fitness is built slowly. It is the honest measure of the work an athlete is actually carrying.
• Fatigue is a 7-day weighted average of the same scores. It reacts fast — one big weekend sends it up, a rest week drops it.
• Form is yesterday’s Fitness minus yesterday’s Fatigue, so today’s training doesn’t change today’s Form. It is the one to watch before a race.

Both averages are exponentially weighted, which is a formal way of saying yesterday counts more than a month ago, and a session fades in influence rather than dropping off a cliff.

Reading Form

Form is the gap between what an athlete has built and what they are currently carrying.

• Form is negative — Fatigue is above Fitness. They are absorbing a hard block. Expected during heavy training; a bad place to race from.
• Form is around zero — training and recovery are balanced. Where most of a season sits.
• Form is positive — Fatigue has dropped below Fitness. They are fresh. This is what a taper is engineering, and why Form usually climbs in the last ten days before an event.

Form staying strongly positive for weeks is not a good sign: it usually means Fitness is falling, not that the athlete is peaking. The point of a taper is to lift Form while Fitness stays high.

Where to find it

Open an athlete and go to their Dashboard. The Fitness / Fatigue / Form chart is the Performance chart; its Source setting is under Chart settings (the sliders icon) on the chart. The Dashboard is customizable, so you can arrange it alongside your other charts from the Charts library; in the mobile app it is also on the Analysis board.

Planned workouts count too (with the Effort and Power & Effort sources; the Power source doesn’t project): TrainerPlan projects the chart forward using the planned effort of the sessions still on the calendar, so you can see what a training block will do to an athlete’s Form before you commit to it.

Training Stress Score® and TSS® are registered trademarks of Peaksware, LLC. CTL, ATL and TSB are terminology used by TrainingPeaks.