Mature iPSC-derived RPE cells are visible by super resolution confocal microscopy. One primary cilium resides in the center of each cell. RPE cell borders are stained showing tight junction markers.

RPE in the most basic of terms is a way to self-monitor to determine how much effort you’re putting in while exercising, says Meg Takacs, CPT, an RRCA-certified running coach and CrossFit trainer.

Amongst HRV, HIIT and VO2 max, you might have encountered RPE or, to give it its full title, rate of perceived exertion. But what does it mean? And is it worth further investigation? Nick Hancock ...