Originally Posted by fstrnu

The integrated internal:external-load ratio assesses the psychophysiological stress experienced by the athlete (ie, heart rate, RPE, blood lactate, etc) during training in the context of the external training load completed and can be used to infer on athlete training status. For example, an increase in the internal load to a standard external load may infer athlete fatigue or decreased fitness, while a reduced internal load (a lower heart rate or perception of effort to a standard external load) indicates that an athlete is gaining fitness and coping with training. Furthermore, this may inform on the consequences of training programs, identify fatigue during team-sport competition, and identify changes in fitness or fatigue status. However, while practically attractive, the implementation of this approach is limited unless care is taken in controlling and quantifying the athlete’s external loads and the environment in which the exercise is completed.

https://journals.humankinetics.com/d...JSPP.2017-0208

Can't imagine how this would be practical indoors on a smart trainer with quantified/controlled external load and environment