Variable resistance training is commonly performed with resistance bands although there are other methods (e.g., using chains). It is a pretty easy concept to understand. As you get closer to completing an exercise or movement the difficulty increases. Think about lifting a heavy weight off the floor. You have to overcome the force of gravity to get the weight moving so a lot of effort or force is needed at the beginning of the movement to lift the weight. Once it is moving though, it becomes easier to keep it moving. On the other hand, with a resistance band the level of difficulty starts easy and increases as you get to the end of the movement where the band is being stretched more.
So how would this benefit athletes? Well, any athlete who is trying to improve their power and explosiveness can use these methods to push past “sticking points” in heavy lifts more effectively. A “sticking point” occurs when the movement seems like it is slowing down noticeably to the point where it looks as though it may stop. This is often the point where the athlete requires some help in the form of a spotter. To keep good technique and maintain safety in your lifts, you may want to try resistance bands as they will give you a smoother, more continuous movement. This will improve your balance, strength and power towards the end of your movements and allow for safer lifting especially when you are training alone.
I like to supplement medicine ball training where you are trying to move an object as fast as possible with some resistance band training. I find the bands are great for pushing and pulling, as well as linear and lateral movements or exercises.
It is important, though, that you make sure when buying resistance bands that you invest in good quality bands. If you spend the extra few bucks to get better quality bands they will last longer and importantly, will be a lot safer. Constantly check your resistance bands for any tears in them. This will help to prevent injury.
Chains is also a good option if you do want to have top replace equipment. Chains are a little more expensive but will last you a lifetime. I just went in to my local hardware store to get mine. They should cut thwm for you to the length you desire.