TRIMP – training impulse – is a numerical indicator of training load. One hour of jogging and one hour of intense cross-country running are the same training volume in terms of duration, but provided completely different training loads! Training load reflects the internal level of physical and psychological stress and is derived from a combination of volume, training frequency, and training intensity.
For endurance sports, Eric Banister and colleagues proposed calculating TRIMP, according to the following formula:
TRIMP (training load) = Duration x HR Reserve e^(HR Reserve x b) where HR Reserve is calculated as (training HR - resting HR)/(max HR - resting HR), e - is the base of the natural logarithm, b - is a coefficient that takes the value of 1.67 for women and 1.92 for men.
The main idea of the TRIMP calculation is that we multiply the duration (in minutes) by the intensity factor. Zihi automatically calculates the TRIMP parameter, provided that the athlete is training with a heart rate monitor or simply knows his or her heart rate during training.