This is an excerpt from Essentials of Strength Training and Conditioning 4th Edition With Web Resource by NSCA -National Strength & Conditioning Association.
One increasingly popular method of applying variable resistance is the addition of chains to traditional resistance training activities such as the bench press or back squat (4, 13, 39, 54). This method of force application is most popular among powerlifters (69, 70), but has become increasingly popular among strength and conditioning professionals working with a variety of sports (22). Despite the increasing popularity and the belief that these methods provide a training advantage, these beliefs are largely unsubstantiated in the scientific literature (13, 14, 39, 54). Some studies, however, demonstrate that the application of chains to traditional resistance training methods such as the bench press can be advantageous (6). Careful inspection of these studies reveals that the means by which the chains are applied to the free weight exercise may influence their effectiveness. Specifically, these studies used a method in which the chain was suspended from the bar without touching the floor until the athlete had reached the lowest position in the squat or until the bar had reached chest height in the bench press (6). While some research seems to support this methodology, much more research is needed to explore the various methods of applying chains to traditional resistance training methods.
Determining Resistance With Chains
The resistance provided by chains is largely dictated by the structure, density, length, and diameter of the chain and must be quantified before the chain is used in a resistance training setting. Additionally, the number of links in a chain will affect the amount of resistance provided by the chain (13, 55). To quantify the loading provided by chains, Berning and colleagues (13) developed a practical chart that related chain link diameter and length to the resistance load provided by the chain. This chart was later modified by McMaster and colleagues (54) to show the relationship between the chain mass, length, and diameter (table 16.1).
As a means of deciding on the barbell resistance to use in conjunction with chains, the absolute load is determined for the top and the bottom portion of the movement (4). The average of these two loads is then calculated and used to modify the barbell load in order to allow the athlete to train in the prescribed range.
As a general rule, Baker (4) recommends that the use of chains be reserved for experienced intermediate- and elite-level athletes who have stable exercise technique, as the addition of chains provides a loading challenge that can affect the athlete’s technique.
Determining the Load to Use With Chains
To determine the load used with chains, the absolute chain resistance at the top and that at the bottom portion of the movement are summed and then averaged. For example, if athletes wanted to train at a 5-repetition maximum (5RM) load in the bench press, they would first determine the 5RM load without the chains. Then, if their 5RM is 120 kg (264 pounds), they would subtract the average chain resistance from this load. If at the bottom position the load is 0 kg and at the top the chain load is 11.1 kg (24.4 pounds), the average is 5.55 kg (12.2 pounds). Thus, the athlete would add 114 to 115 kg (251.8-253.0 pounds) to the barbell to achieve the appropriate loading.
Applying Chains to Free Weight Exercises
Generally, the application of chains to traditional resistance training methods allows for a linear increase in the applied resistance (54). Ways to apply chains include letting them touch the floor from the fully extended position during the movement (13) or hanging them from lighter chains (figure 16.1), which allows them to touch the floor only upon reaching the lowest portion (figure 16.2) of the movement pattern (i.e., bottom of the squat or at chest level during the bench press) (4, 6). Baker (4) suggests that the second method may affect the velocity of movement in three distinct ways. Firstly, the total barbell - chain complex comes into play only at the top of the movement (i.e., extend portion) when the chain links have been lifted off the floor. At the bottom of the movement, the links are in full contact with the floor, providing a reduction in load and allowing the athlete to accelerate the barbell at a faster rate. Secondly, it is possible that a within-repetition postactivation potentiation effect may occur in response to a greater neural activation. Specifically, when the chains pile on the floor and the mass of the barbell decreases, a greater neuromuscular activation may occur, allowing for an enhancement in movement velocity. Finally, it is possible that the decreasing resistance at the bottom portion of the movement may cause a more rapid stretch - shortening cycle. Baker (4) suggests that this happens in response to the eccentric unloading that occurs when the chain links pile on the floor at the bottom of the movement and a quicker amortization phase occurs when the athlete shifts from eccentric to concentric muscle action.
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