If you look around at different Crossfit gyms and other non-geared Powerlifting gyms, you will see an increasing use of bands and chains for squatting and deadlifting, all in the name of "speed work." In my opinion, there are some huge errors in this style of training, specifically for raw lifters, and ESPECIALLY for brand new lifters.
The purpose of bands and chains is to increase the weight of the bar as the repetition gets closer to lockout. As the tension of the bands increase (or the weights of the chain increases, the higher off the ground it is), the lifter must continue acceleration throughout the lift to achieve a fast rep lockout. The theory is that this will have carryover to squats and deadlifts when bands and chains are not used. I feel that this is false, or at least faulty information.
I am going to paraphrase Chad Wesley Smith a bit here (If you don't know who he is, change that). Chad has basically stated chains and bands are a bit silly for raw lifters, because unlike geared lifters, the most difficult part of the squat tends to be the "hole" (bottom of the squat), or the "sticking point" (roughly at parallel), not the top half of the lift. Since bands and chains are designed to increase the weight of the bar as it gets close to the top, how much carryover would this have to increasing power out of the hole? Not too much, really. In my opinion, it would make much more sense for Crossfitters to get rid of the bands and chains if they are actually trying to increase overall squat strength, instead of loading a light 135lb bar with 50lbs of chains.
What absolutely doesn't make sense to me is having new CF clients (IE, males that can't yet squat 200lbs) put 95lbs on the bar, and thin red bands, as if this will somehow make them stronger. It seems like bands and chains are added because they look sexy and new, and chains just make you feel more like a badass. Honestly though, it would make much more sense and get better results to just have new clients increase the weight of actual plates on the bar, to increase strength out of the hole, rather than adding lots of superfluous items to the bar.
In this same vein, is it really necessary to have new clients do "speed work" with 45-60% of their max? I do not think so. Simply put, anyone can move a weight quickly when it is light, because it is light. As we have stated before, if you want to move heavier weights quickly, you need to practice moving heavier weights quickly. Doing ten sets of three back squats with 50% of a new client's max is not really going to do anything for their speed when they are under heavy weights. Crossfitters get PLENTY of speed work with the amount of metcons involved in that training style, 50% back squats are not the place for that kind of speed work, especially with new clients. If you really want to get stronger, you need to work on getting stronger. If you are technically deficient, you really have no need working with bands and chains unless you have been lifting for many many years: doing 95lb back squats with 50lbs of chains is not going to take your 300lb to 405lbs, and it is not going to prepare you to handle heavier weights.
I understand that bands and chains have their place in proper training regimens, such as Powerlifting (especially geared Powerlifting). However, I don't feel that Crossfit is the appropriate place for bands and chains, simply because they strength carryover is not going to be present.
I could get into why bands and chains are a TERRIBLE idea when working on snatch and clean & jerk with new lifters, but I will save that for another time. What are your thoughts on the subject?