When it comes to those who are looking to maximize strength and/or muscle gain, you will eventually reach a point where eccentric training might be just the tool for the job. I only recommend this type of training for advanced trainees with several years of serious training under their belt, and preferably under the guidance of a PICP coach.
Eccentric training is important for three things. It increases muscle hypertrophy (size), increases potential for further strength gain, and improves deceleration performance. The simplest way to accomplish this is to control the eccentric portion of normal sets. For example, in a bench press, this would mean lowering the bar to the chest. You can do as short as 4 seconds down when performing multiple reps, all the way up to 10 second eccentrics for single reps.
For the most advanced trainees, you will perform this type of work with supramaximal weights. In other words, you will lower a weight heavier than what you can push up for the bench press. One of the best and safest ways to do this is with the use of weight releasers or eccentric hooks. I stress again, this is for advanced trainees under the guidance of a PICP coach. See the video on FunctionalFitMag.com to see how these bad boys work.
One last use for eccentric hooks and weight releasers is for rehab work. If injury is preventing a person from handling a load in a specific range of motion, you can use a weight releaser so that the load comes off before that range, while still achieving a greater training effect in the healthy range.
I love to use them for increasing strength and power. Research has shown that powerlifters who used the most weight on the bench press were the ones that lowered the weight slower. However, those hooks are not to be taken lightly, only experienced lifters and athletes should use them, or at least have already been introduced to some kind of eccentric training. The extreme level of soreness that comes with it will make you understand that it is very useful. There are plenty of good versions out there, and you must make sure that you also get the squat attachment. You could do it on the first eccentric of the first rep or you could also get two spotters (good ones) that will load the hooks on the bar on the last good concentric repetition, and do one last eccentric of 10 seconds. Adding eccentric hooks or weight releasers to the mix is very inexpensive and always brings in great results. – Eric Falstrault