Training Load Calculator (TRIMP) Formula

Understand the math behind the training load calculator (trimp). Each variable explained with a worked example.

Use the Training Load Calculator (TRIMP)

Formulas Used

TRIMP Score

trimp = duration_min * hr_ratio * 0.64 * exp(1.92 * hr_ratio)

Heart Rate Reserve Used

hr_pct = hr_ratio * 100

Variables

VariableDescriptionDefault
duration_minSession Duration(minutes)45
avg_hrAverage Heart Rate(bpm)145
resting_hrResting Heart Rate(bpm)60
max_hrMax Heart Rate(bpm)190
hr_ratioDerived value= (avg_hr - resting_hr) / (max_hr - resting_hr)calculated

How It Works

TRIMP (Training Impulse)

TRIMP quantifies session training load by combining duration with exercise intensity.

Formula (Male)

TRIMP = Duration x HRratio x 0.64 x e^(1.92 x HRratio)

Where HRratio = (Avg HR - Rest HR) / (Max HR - Rest HR)

Interpretation

TRIMPLoad Level <50Light 50-150Moderate 150-300Hard >300Very hard

Worked Example

A 45-minute run averaging 145 bpm, resting HR 60, max HR 190.

duration_min = 45avg_hr = 145resting_hr = 60max_hr = 190
  1. 01HR ratio = (145 - 60) / (190 - 60) = 85 / 130 = 0.654
  2. 02TRIMP = 45 x 0.654 x 0.64 x e^(1.92 x 0.654)
  3. 03= 45 x 0.654 x 0.64 x e^(1.256)
  4. 04= 45 x 0.654 x 0.64 x 3.512 = 66 (Moderate)

Frequently Asked Questions

What is TRIMP used for?

TRIMP helps track weekly training load to manage fatigue, prevent overtraining, and periodize training programs.

What is a good weekly TRIMP?

Recreational athletes often accumulate 200-400 weekly TRIMP. Competitive athletes may exceed 600. Increase no more than 10% per week.

Why does TRIMP use an exponential factor?

The exponential accounts for the disproportionately greater physiological stress of higher-intensity exercise compared to low-intensity work.

Ready to run the numbers?

Open Training Load Calculator (TRIMP)