Modern cycling trainers show a video and correlate resistance with what’s being shown on screen. You can “ride” a stage of the Tour de France and it will be tougher as you ride up steeper hills. Zwift has created virtual courses that cyclists from around the world can ride simultaneously, interacting with each other. It records detailed information about your virtual progress in a .FIT file, along with your heart rate, cadence, and other data from third party monitors you may be using.
Using fitparse, I created software that converts these into a format that Mathematica can understand, and using Mathematica, it is possible to break down the data a million ways. A few graphical examples are shown below.