What is accommodating resistance? Accommodating resistance is the idea of adding resistance that fits the strength curve of a movement. The strength curve of a movement is the concept that muscles are stronger or weaker depending on the length they are within a movement. This is why the bottom position of the squat is the weakest and the top position is the strongest. In the case of a squat, the strength curve is an ascending strength curve, where you get stronger as you move closer to the finish of the movement. Accommodating resistance is designed to add weight at the stronger points and reduce weight at the weaker points. Tools like bands and chains help accomplish this. As the weight is lifted, the bands become more stretched, or more chain links are picked up, increasing the mass or tension on the bar. This in turn forces the muscles to continue to produce more and more force as the weight is lifted. The difference in strength between the bottom position of a squat and the top can be quite a bit, so adding weight as the weight is lifted forces the muscles to continue to work at higher relative intensities compared to their potential max force producing capabilities.
When we lift lighter weights as fast as we can, part of the range of motion is responsible for decelerating the bar itself. For example, if we lift light weight, say 50% of our one rep max as fast as we possibly can, we actually have to decelerate the bar at the end range of motion. This is where using accommodating resistance has the potential to shorten the range of motion where deceleration occurs, because load is constantly being added to the bar as it is lifted. The reason why deceleration is bad is because muscles are no longer producing force to move the bar, but instead producing force to actually stop the bar from moving. With the addition of accommodating resistance, force production through the full range of motion can be potentially trained in a much more effective way. The other option is to just throw the object you are lifting, or jump with it. Obviously this doesn’t really work well with the bench press, but if you have a medicine ball for throws or a trap bar for jumps, these options seem to work as a possible alternative.