By Zencalcy Editorial TeamLast reviewed About us
TRIMP stands for training impulse, a single number that scores how much a session loaded your body. It multiplies the time you trained by how hard your heart rate was, weighting the hardest minutes more, so a long easy session and a short hard one can be compared on one scale.
Score a session with the Banister training impulse.
ΔHR = (HRexercise − HRrest) / (HRmax − HRrest) TRIMP = minutes × ΔHR × (men: 0.64 × e^(1.92 × ΔHR)) TRIMP = minutes × ΔHR × (women: 0.86 × e^(1.67 × ΔHR))
The exponential weighting means hard minutes count for much more than easy ones. The score is relative to you, so compare sessions with each other rather than against another person.
| Symbol | Meaning |
|---|---|
| HRmax | Your maximum heart rate in beats per minute. |
| HRrest | Your resting heart rate in beats per minute. |
| HRexercise | The average heart rate across the session. |
| minutes | How long the session lasted, in minutes. |
| sex | Which weighting equation to apply, men or women. |
For a man with a maximum of 190 bpm and a resting rate of 60 bpm, an average of 150 bpm gives ΔHR = (150 − 60) / (190 − 60) = 90 / 130 ≈ 0.69. TRIMP = 40 × 0.69 × 0.64 × e^(1.92 × 0.69) ≈ 67.
TRIMP, the training impulse, turns a workout into a single number by combining how long you trained with how hard. The Banister version first converts heart rate into a fraction of your reserve, then multiplies duration by that fraction and by a weighting factor that grows exponentially with intensity.
For men the weighting factor is 0.64 times e to the power of 1.92 times the reserve fraction, and for women it is 0.86 times e to the power of 1.67 times the fraction. The exponential term is the key idea: a minute at high intensity counts for much more than a minute at low intensity, so hard sessions drive the score up sharply.
Because TRIMP gives one comparable value per session, it is used to track training load across a week and to watch the balance between stress and recovery. Summing daily TRIMP and comparing short and long term averages is a common way to spot a ramp that climbs too fast. The exponential weighting matches the observation that intensity, not just time, drives fatigue.
Continue with the VO2 Max from Heart Rate Calculator, Anaerobic Threshold Calculator, or the Critical Power Calculator — or browse more heart rate & performance tools and all sports calculators.
The scale is personal, so a hard session might score in the hundreds while an easy one scores in the tens. What matters is the trend and how it compares with your own easy and hard days.
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Last reviewed: September 2026. See how we build and check every tool on the about page.
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Content updated: September 2026