The Colorado Experiment was a bodybuilding experiment run by Arthur Jones using Nautilus equipment at the Colorado State University in May 1973.
It is of interest due to its claims that incredible results can be achieved with a small number of sessions using single sets of high intensity repetitions to momentary muscle failure focusing on negative or lowering multi-joint exercises. The first subject, Casey Viator, gained of muscle in 28 days and the second, Arthur Jones, gained in 22 days.
These claims are considered controversial because it was only performed with two subjects who were not "average," but regaining pre-existing muscle mass. Mike Mentzer did compare these results to the results of top bodybuilder Arnold SchwarzeneggerâÂÂs results of a gain of approximately (verbal estimates from Arnold of starting at and ending at ) while working out 4 hours per day, 6 days a week for 4 months.
After stopping exercise for more than two years, 1971 Mr America, Viator was invited by Arthur Jones to participate in what was to be known as the Colorado Experiment. The primary purpose was to prove or disprove the efficacy of pure Nautilus training in developing a champion physique. This study was performed at a time where the vast majority of amateur and professional bodybuilders developed their physiques through traditional workouts involving the use of barbells, dumbbells, and cable equipment. The results concluded that Viator gained more than (of muscular mass) in 28 days with only 12 high-intensity workouts, each of which were less than 30 minutes. Viator actually gained , but Jones conjectured that he lost of fat, giving him a net lean gain of . In fact, he most likely gained fat, as Mike Mentzer later claimed Viator was "literally force-fed." By comparison, the typical amount of muscle gain (not fat) in an average person is per year.
Muscle gains of eight of other subjects: