Louie Simmons in the 1980’s and 1990’s popularized the use of bands and chains coining the term accommodating resistance. It use is meant to help match the strength curve in an exercise allowing a lifter to build speed and strength through their sticking point.
For example. In a squat the hardest part of the lift is at the bottom. As the lifter stands up the lift moment arms reduce causing the lift to get easier.
This is due to the larger moment arms created at the bottom of the lift. The further away the the fulrcum is from the weight the more force it needs to exert to overcome the resistance.
Bands and chains are meant to vary the the resistance of the movement as the lifter goes through the range of motion, making the way up more difficult than it typically would be. This is also considered variable resistance.
This does two things
1) It allows the lifter to load a part of the lift that was inherently easy to begin while enabling strength to develop at higher spots in the range of motion
2) It makes the lifter have to continuously drive with maximum intention. As a lift comes closer to completion the lift gets easier and we tend to not “push” as hard. The bands force us to keep pushing hard.
Bands and Chains are Similar But Different
Similarities include
-Varying resistance throughout the range of motion, less resistance on the way down (eccentric) and more resistance on the way up (concentric)
-Speed development is naturally developed in order to finish the lift
-Helps stabilize the movement by keeping the bar path vertical (if bands are set up straight down, and chains naturally hang down vertically)
Differences
Bands
-Overspeed the eccentric portion contributing to more potential energy on the concentric phase
-Resistance is not linear its exponential. The more the band is stretched the more resistance increase
-Bands wear out leading to loss of tension, uneven wear from band to band, and they break
Chains
-Lower center of mass which makes the lift more stable
-Chain weight is fixed meaning for every chain link that comes off the ground a specific amount of weight is added to the bar. The resistance is linear.
Accommodating resistance develops two qualities of strength.
1) Strength-Speed – is the ability to move maximal loads as fast as you can. Loads will be above 90% and ~45% of resistance will be accommodating resistance.
2) Speed-Strength – is the ability to move a moderate-loads as fast as possible. Loads we will equal ~ 65-75%. Accommodating resistance will constitute about 25%.
The goal of using accommodating resistance is to develop both qualities, the ability to push through a lift’s sticking point and the ability to produce high levels of force using speed. When properly programming in both will contribute to gaining more strength.