SO HERE YOU HAVE IT! :)
Movements become ballistic at the end of the range of motion during large, multiple-joint exercises, such as the bench press, squats, and deadlift. In other words, there's less load on the muscles as you get closer to lockout and little motor unit activity in the prime mover muscles (the muscles doing the work). Lifting with resistance bands or chains attached to the bar increases the load at the end of the range of motion.
Australian scientists found that force and power output was greater during back squats performed on a Smith Machine when using resistance bands than during traditional weight training. Also, resistance bands are effective when doing traveling lunges and side shuffles...keeping the tension and force continuously while performing these movements.
They used a force platform to determine the forces created during the exercise. Muscles tend to get larger and stronger when subjected to more tension, so we may infer from this study that training with resistance bands (or chains) is beneficial. It can also be stated that training with resistance bands or chains does increase strength and lean muscle mass more than traditional training methods. SO GOOD NEWS FOR ALL OF THE CLIENTS THAT TRAIN WITH ME...JUDY IS HERE TO STAY!!! LONG LIVE JUDY!!!
Journal Strength Conditioning Research, 20: 268-272, 2006.