Training Impulse (TRIMP)

Q: What is a good TRIMP score?

It depends on the formula and workout duration. Using the Banister method, an hour of easy riding typically scores 40-80, a solid endurance ride 80-160, and a hard hour around threshold 150-180. Most trained athletes accumulate roughly 300-700 TRIMP per week. Because variants like Edwards TRIMP use different scales, always compare scores calculated with the same formula.

Q: What is the difference between TRIMP and TSS?

TRIMP is calculated from heart rate and duration, while TSS (Training Stress Score) is calculated from power data relative to your FTP. TSS is more precise for cycling because power responds instantly to effort, while heart rate lags and drifts. TRIMP shines when there is no power meter - running, swimming, or riding on a bike without power. On the TSS scale, 100 points equals one hour at threshold; Banister TRIMP for the same ride lands around 150-180, so the numbers are not interchangeable.

Q: How do I calculate TRIMP?

The Banister formula is TRIMP = duration (minutes) x HRr x 0.64 x e^(1.92 x HRr) for men, where HRr is your heart rate reserve fraction: (average HR - resting HR) / (max HR - resting HR). For women the weighting is 0.86 x e^(1.67 x HRr). The exponential term means time at high heart rates counts disproportionately more than easy riding. Use the calculator on this page to get your score from any workout.

Q: Does TRIMP work for running and other sports?

Yes - that is one of its biggest strengths. Because TRIMP only needs heart rate and duration, it produces comparable stress scores across running, cycling, swimming, rowing, and any other endurance activity. This makes it useful for triathletes and multi-sport athletes who want one consistent load number across sports.

TRaining IMpulse (TRIMP) estimates the training stress of a workout based on heart rate data and duration. It weights harder efforts more heavily — time spent at higher heart rates contributes exponentially more than easy riding.

TRIMP Calculator

Score any workout with the Banister formula - all you need is heart rate and duration.

Workout duration (minutes)

Average heart rate (bpm)

Resting heart rate (bpm)

Maximum heart rate (bpm)

Male Female

How TRIMP Is Calculated

The original method comes from Dr. Eric Banister (1991). It multiplies workout duration by your heart rate reserve fraction and an exponential weighting factor:

TRIMP = duration (min) × HRr × 0.64 × e ^{1.92 × HRr}

where HRr is your heart rate reserve fraction: (average HR - resting HR) ÷ (max HR - resting HR). For women the weighting is 0.86 × e ^{1.67 × HRr} , reflecting differences in lactate accumulation profiles.

The exponential term is the clever part. It mirrors how blood lactate rises with intensity, so an hour at 85% of your heart rate reserve scores roughly four times more than an hour at 40% - not just twice as much. That is what makes TRIMP a measure of training stress rather than just training time.

TRIMP Variants

Several refinements of the original formula are in common use:

Banister TRIMP - the original exponential formula above. Uses average heart rate, so it slightly underestimates very variable interval workouts.
Edwards TRIMP - splits the workout into five heart rate zones and multiplies time in each zone by 1-5. Simpler, and handles intervals better because it scores each minute where it actually happened.
Lucia TRIMP - three zones anchored to physiological thresholds (below VT1, between thresholds, above VT2), weighted 1-3. Used widely in research on professional cyclists.
Session RPE - not heart-rate based, but often grouped with TRIMP: duration × perceived exertion (1-10). A useful backup when you have no HR data at all.

The variants don't share a scale. A ride scoring 150 Banister TRIMP might score 220 with Edwards - pick one method and stick with it.

TRIMP vs TSS vs hrTSS

Training Stress Score (TSS) answers the same question - how much stress did this workout create? - but from power data instead of heart rate. Power responds instantly to effort, while heart rate lags behind surges, drifts upward in heat, and varies with sleep, caffeine, and stress. For cycling with a power meter, TSS is the more precise tool; you can score a ride with our TSS calculator .

TRIMP earns its keep everywhere power data doesn't exist: running, swimming, indoor classes, or riding without a power meter. hrTSS is the bridge between the two worlds - a heart-rate-based estimate rescaled so that 100 points equals roughly an hour at threshold, making it directly comparable with TSS. FormBeat uses hrTSS automatically for activities without power, so your training load stays complete across every sport.

What Counts as a High TRIMP Score?

Using the Banister formula, typical single-workout scores look like this:

Under 80 - light session: recovery spin or short easy run.
80-160 - moderate: a solid endurance ride or steady hour of tempo.
160-250 - hard: long endurance day or an intense interval session.
Over 250 - very hard: a race or big mountain day. Plan recovery afterwards.

Most consistently training athletes accumulate 300-700 TRIMP per week. As with all load metrics, the trend and the week-to-week change matter more than any single number - a sudden doubling of weekly TRIMP is a bigger red flag than any one big ride.

Limitations Worth Knowing

Heart rate is an indirect signal, and TRIMP inherits its quirks. Cardiac drift inflates scores on long rides in the heat. Sprints and short anaerobic efforts barely move average heart rate, so explosive interval sessions get underscored. Dehydration, caffeine, illness, and poor sleep all shift heart rate independently of training stress. None of this makes TRIMP useless - it just means scores are best compared across similar workouts, and combined with power-based metrics when available.

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