True Fitness CS8 Owner's Manual page 87

Appendix C
Constant torque is used in a modified way in Bike Mode. In
addition to constant resistance for a given "gear, " additional torque
is applied to simulate wind and road resistance, as well as to
compensate for different body weights.
Personal Power was initially designed to vary workload at a
The
1:1 ratio with body weight, just like a METs-based exercise
Personal
prescription. However, it turns out that human endurance and
Power
power generating capability varies with the 2/3 root of body
Calculation
weight, not straight body weight. This relationship can be seen in
everything from weightlifting world records to distance running
competitions. (See McMahon and Bonner, On Size and Life
(1985), page 55).
Since METs do not work the way they're supposed to, Personal
Power is based on a new unit of measure that correctly accounts
for body weight. This new unit of metabolic measure, called the
T-MET, is defined as:
T-MET = watts / (kg) 2/3
where watts is power applied to an external machine from the
exerciser, and kg is the exerciser's body weight in kilograms.
CS 8.0 Owner's Guide 99