I do wonder about "transcriptome" activity being a good metric. One of the best ways to induce a huge amount of transcription in an organism is to induce heat shock (eg: put your flies or whatever model organism at an uncomfortably high temperature) and transcription goes through the roof. A lot of transcription factors (proteins that comprise the on/off switches) have names that begin with HS... They are called "heat shock" proteins because they are discovered by inducing transcription via this method. Any other method that similarly induces a lot of physiological stress will also induce transcription, basically putting cells into an emergency response mode.
So does increased transcription in old people mean they are getting more benefit out of heavy-load exercise, or does it mean they are getting stressed much more by heavy-load exercise, due to their age and vulnerability?