I have never heard that before, interesting if true.... I know that high level rowers have some of the highest absolute VO2 max results ever recorded (L/min), but because of the physical size required for rowing they dont have the highest relative levels (L/kg/min) compared to the likes of marathon'ers or cc skiing, but are still very high. In general terms, i rate rowing as the number two exercise to improve fitness levels, only behind boxing. I use the rower all the time on cardio days and for warm ups.