While performing research at the University of Illinois in the early 1950s, Orban had noticed, when testing oxygen intake, that long periods of exercise did not necessarily lead to significant improvement. This led him to the conclusion that the intensity of exercise was more important to improving fitness than the amount of time spent on it. He incorporated this conclusion into his proposed exercise plan for the RCAF. This concept drew a negative reaction from others in the field at the time but it proved its worth in the three years of testing that the RCAF performed before releasing the program in 1961.