Super Slow Training was popularized by Mike Mentzer in the 1970s. Super-slow was part of his heavy-duty system that has today become known as High Intensity Training. Arthur Jones the inventor of Nautilus Strength Training machines worked with Mike to develop his systems that included: tri-sets, giant sets, super slow, forced reps, stripping and other high intensity training programs. Mikes training systems lead to great bodybuilding success (he won several major bodybuilding titles).
Over the past few years several research articles have been published all showing quite clearly that Mike was right. Its unfortunate that his untimely death precluded him from seeing science prove his methods. During his life he received a great deal of criticism from the bodybuilding community that believed in high-volume training.
Dr. Wayne Westcott, one of our countries leading exercise science researchers and a good friend of mine has shown that super slow training increases strength over 60% when compared to high volume training (over an 8 week study period). The only negative was that the people in the super slow group stopped doing super slow at the completion of the study because they felt super slow was to tough, this despite the great gains they saw.
The super slow program: after thorough general warm-up and specific muscle group warm-up prior to each super slow exercise, prepare yourself mentally for a high-intensity set. Perform one set of one exercise per body part of 4 6 reps. Each rep will be 10 seconds on the concentric contraction and 4 seconds on the eccentric contraction. You should achieve concentric failure between 4 6 reps; the resistance will be lighter than a normal 4 6 RM set, probably by 15-20%. Since you will only do one work set, you do not need lengthy rest periods between sets, therefore you can complete a thorough workout in approximately 20 minutes and get more out of it than the guys spending 3 hours (or more).
One benefit I like is that super slow is much gentler on my joints and I definitely enjoy getting in a great workout in 20 minutes.