Training Impulse (TRIMP)

About this calculator

TRIMP (Training Impulse), developed by Eric Banister, quantifies how hard a workout was by combining session duration with heart-rate intensity into one number: TRIMP = duration (minutes) × heart-rate reserve fraction × a weighting factor (0.64 × e^(1.92 × HRr) for men, 0.86 × e^(1.67 × HRr) for women) that exponentially weights harder efforts more heavily than easy ones, since a hard interval session stresses the body disproportionately more than the same duration at an easy pace.

Endurance coaches and sports scientists use TRIMP to track cumulative training load across a week or season, feeding it into fitness-fatigue models (like the Banister impulse-response model) that help predict overtraining risk or plan a taper before a race. It gives a single comparable score across very different workouts — a short, intense interval session and a long, easy run can produce a similar TRIMP even though they look nothing alike on paper.

This calculator takes your session duration and heart-rate data and returns the Banister TRIMP score for that workout.