Supramaximal Eccentric Training (SET) is a complex name for a simple training protocol. In the most basic sense it means using more weight on the negative (eccentric) portion of a lift (the lowering of the bar in the bench press) than you could handle concentrically (pressing motion in the bench press). In other words, it means doing heavy negatives.
Studies have shown that we can handle 20% to 60% greater loads eccentrically than we can concentrically. During traditional lifting we choose our load based on what we can complete a full lift with, which is why the eccentric portion of our lifts are repetitively underloaded.
A study in the Strength and Conditioning Journal revealed greater improvements in strength after a period of maximal eccentric loading (with spotters helping on the concentric portion) versus a period of traditional loading. The increase in strength was accredited to larger total forces experienced by the neuromuscular system.1 The research supports what serious powerlifters have known for years: heavy negatives get you stronger!
SET It Up
Now that we have the science out of the way, let’s get down to the nitty-gritty and figure out what this means to the iron warrior.
During SET all we care about is the eccentric portion of the lift, so weights will far exceed your 1RM.
There are a couple ways of achieving this supramaximal eccentric load. The first requires having at least one spotter. Load the bar with 105% to 115% of your 1RM and lower it as slowly as you can. Once you lower it to your chest, have your spotter lift the weight off and back up to lockout.
The second viable way to achieve this load requires the use of weight hooks. Load the bar with less than your 1RM (maybe about 80%) and then load up the weighted hooks so that the resulting sum of all the weight is 105% to 115% of your 1RM. Set up the hooks so that they release when the bar is at your chest. Lower the bar as slowly as possible, and once at your chest the hooks with the added weight will release and you can press the bar up (or you can have your spotter help with the concentric portion).
Both methods achieve the same goal, but if you have a pencil neck for a training partner it may be safer to use the second method because they won’t have to lift as much weight off of you.
Aside from all the physical benefits of doing heavy eccentrics, it also has a positive effect on the mental aspect of your lifting. If you’ve been handling 115% eccentrically, you’ll be more confident heading into your next max-out day. Now that you know you can lower the weight under control you won’t be scared of it crashing down on you when you go to do a full lift.
Heavy eccentric movements have also been shown to increase delayed onset muscle soreness (DOMS) and can take anywhere from 7–10 days to fully recover from. So be wise and don’t do this more than once a week for four weeks in a row. Using SET too much can easily lead to a state of overtraining. 
Do a four-week cycle that incorporates heavy eccentrics once a week (after your working sets of bench press), then stay away from them for 6–8 weeks. Start out by using 105% for three sets of 3–5 reps. Because of the extremely high loads involved in SET, it’s not something that the novice lifter should try. Make sure your base is strong so that your muscles, tendons and ligaments are prepared to successfully handle extreme loads.
If you’re looking for something to supersize your bench, load that bar up and incorporate supramaximal eccentric training.
 Tobin, D. (2014) Advanced Strength and Power Training for the Elite Athlete. Strength and Conditioning Journal, 36, 59-65
 Divakara K.(2014) Postexercise Muscle Soreness. Retrieved from: http://emedicine.medscape.com/article/313267-overview