Some time ago I asked a question about how to replace deadlifts with resistance bands: Resistance band deadlifts. One point was that the resistance band doesn't offer a constant resistance but it increases monotonically with the stretching of the band.
Recently I discovered the cable pull through as a safe way to train the posterior chain:
(Image from http://experiencelife.com/article/the-best-exercises-youre-not-doing/)
Now I asked me again whats about resistance band pull throughs. Since the forces are different in the cable version vs. resistance band version (constant force vs. increasing force) one might guess that the muscle activation and thus the training effect is different. On might also ask if one needs to use a modified technique for the resistance bands or if one should add another exercise to get the same effect with the resistance bands as with the cables. Perhaps there is a general answer to those questions without referring to a specific exercise (you can substitute many cable or dumbbell exercises in principle with resistance bands).
So I want to know the following specifically to this exercise and in general:
- What does the constant force vs. increasing force fact imply concerning
- training effects aiming to build a proper working/functional, healthy muscle system
- training effects aiming at bodybuilding (i.e. how the results will look like)
- are there any technique variations you must have in mind?
- are there any additional exercises you should to to compensate the shortcomings of the resistance bands?
By asking google I already found this passage from bodylastics which doesn't need to be very objective since it's a resistance band manufacturer:
Another unique benefit of elastic resistance that free weight resistance does not offer is linear variable resistance. What this means is that, as the range of motion of the exercise increases, the resistance provided by the elastic equipment increases. For example, when doing a biceps curl, as you curl your hand up toward your shoulder, the resistance of the elastic tubing increases. This is due to the physical properties of elastic material. As its length increases (from being stretched), it provides more resistance11. One of the benefits of this is that as the range of motion increases and the resistance increases, the number of muscle fibers that are being used in the exercising muscle increase. The more muscle fibers being used, the greater the adaptations in muscle strength that can be achieved with the training program. This benefit is not offered by free-weight resistance. Another reason linear variable resistance, as provided by elastic resistance, is beneficial is due to what is known as the strength curve of muscles. The linear variable resistance provided by elastic tubing better mimics the strength curves of most muscles. A strength curve refers to the way a muscle’s or muscle group’s strength changes over a range of motion. Because of their anatomy, most muscles increase in strength over the range of motion until a certain point. Again using the biceps curl as an example, as you curl the hand toward the shoulder, the muscle gets stronger up until about the halfway point of the range of motion. Thus, the biceps muscle is weakest at the start of the exercise and strongest at the halfway point of the exercise. When doing a biceps curl with a free weight, the individual is limited to how much resistance he can use by how strong the biceps are at the beginning of the exercise (its weakest point). That means that during the biceps curl, the muscle is not receiving adequate resistance when the muscle is in its strongest point in the range of motion. When performing a curl with elastic tubing, however, the resistance increases as the range of motion increases. This means the muscle is receiving greater resistance at its strongest point in the range of motion and therefore is receiving more adequate resistance to better stimulate strength adaptations.
