According to Vladamir Zatsiorsky, there are 3 effective methods to maximise your time spent in the gym lifting weights. 1 is accentuation (work is done at the precise angles at which maximal force is made)2 is peak contraction (maximal strength is developed at the weakest body position such as in the ‘hole’ in a squat)3 is accommodating resistance (near maximal force is developed throughout the complete range of motion). Accommodating resistance comes in a myriad of forms, including weight releasers, bands, and chains. By attaching chains to the barbell in a precise fashion, they will unload as the lifter lowers into the bottom of a squat. As the lifter rises concentrically, the chains load again to accommodate resistance. Ideally, there has to be a correct amount weight in the bottom of the lift as well as at the top. The former Soviet Union was quite famous for using weight releasers. They used to overload a bar and have the individual lower him or herself to the bottom of the squat. At that point, spotters stripped off a pre-set amount of weight, and the individual executed the concentric phase unaided. Bands were started being used in the mid-1990, and have provided great accommodating resistance. Many believe that bands only help accommodate resistance on the concentric phase, but the eccentric phase is greatly boosted because the bands deliver added speed, which causes a superior stretch reflex and Golgi tendon reflex. To cultivate certain kinds of strength, you must stick to a certain combination of barbell weight to band ratio. Doing so will maximise performance as well as to help build tremendous jumping ability as well. BibliographySimmons, Louie. Westside Barbell Book of Methods. Columbus, OH: Westside Barbell, 2000. Zatsiorsky, Vladimir M. Science and practice of strength training. Champaign, IL: Human Kinetics, 1995.