RChung

The idea of being able to combine aerobic TSS with some version of a non-aerobic TSS is complicated because they're not measuring the same thing. They may measure something related in terms of fatigue but the physiological systems seem pretty different, so the stresses are almost orthogonal. (Not quite, but almost). What you might want to measure is something related to substitutablility and complementarity. We do construct measures or indices of complementary things, sometimes scaled independently, sometimes not. (Think of composite measures like foot-pounds or Newton-meters or person-hours or per member per month). There, we're pretty much explicitly saying that the two components are orthogonal.

This is a long way of saying that rather than try to get resistance into a TSS framework, you may want to think about a new combined metric.