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Do resistance bands work or are there better alternatives?

Resistance bands are – just like the Kynett ONE – easy to carry and they seem to work the same as flywheel training. Still, there are important differences that we will explain in this article.

 

A resistance band or elastic band cannot create an eccentric overload like a flywheel can. Resistance bands can also cause dangerous situations. Yet these are not the points we want to discuss. To clarify the main difference, we will take a closer look at the functioning of your muscles.

 

Muscle functioning

A muscle generates force by contracting. If you zoom in on a muscle you will see two parts. You can compare these two parts with ropes (1) and rows of people (2).

 

Image 1: when you zoom in on a muscle you see “ropes” and “rows of people”.

 

When contracting the muscle, the people pull the rope. The tug of war ensures that there is more and more overlap between the ropes and the rows of people: the muscle shortens. If you want to know more about this, search for the cross-bridge cycle of actin and myosin.

 

Image 2: When the people pull in the rope, more overlap is created: the muscle shortens.

 

A muscle that is completely lengthened (stretch) has little overlap between the ropes and the people see image 1. You can imagine that it is difficult for people to pull the rope in this situation. In other words, it is difficult to deliver a lot of force.

 

As the overlap increases due to the tug-of-war, see image 2, the muscle can deliver more force. More people can pull the rope.

 

However, when the muscle is almost completely contracted, there is very little rope left to pull on. In this final situation you can again deliver little force, see image 3.

 

Image 3: with a lot of overlap between the ropes and people, your muscle can deliver little force.

 

Force-length relationship

The muscle force-length relationship that follows from this, summarizes the relationship between muscle length and muscle force. Image 4 shows at the bottom left that an (almost) completely shortened muscle can deliver little force. You can also see at the bottom right that a muscle at (maximum) length can only provide little force. Between these two extremes, there is an optimal degree of overlap. This is when the muscle can deliver maximum force.

 

Image 4: force-length relationship

 

If you want to train a muscle, you will have to challenge the muscle. Two muscle lengths are the most important:

  • First of all, the muscle length in which you are strongest. This is roughly halfway through the exercise where there is a good overlap between the ropes and the rows of people. At this point you want to challenge the muscle with a lot of resistance.
  • Second, the muscle length where there is only little overlap between the ropes and the rows of people (right side image 4). This is usually at the beginning of the exercise. This research shows that focusing on this starting phase yields 3x more results than focusing on the phase in which there is already (too) much overlap.

 

In a nutshell, you want the external resistance (resistance band, flywheel, dumbbell…) to match your muscle force-length relationship (image 4). Only then, you challenge your muscles during the entire movement. The initial phase and middle phase of the exercise appear to be extra important.

 

Back to the resistance band

You can already feel it coming… the resistance band (only) creates resistance in the end position of an exercise, as soon as the band is stretched. This was precisely the least important phase. Depending on the resistance band, the ratio looks like this:

 

Image 5: muscle force-length relationship + resistance of a resistance band.

 

At the end of the exercise (left in the graph) the band delivers a lot of resistance, while your muscle can only provide little force. The line is, as it shows, above your own ability, making the exercise too hard in this phase. However, in the middle and right of the graph, the line of the resistance band is below your own ability. In other words, you are not challenged enough to become stronger.

 

Unfortunately, we see that it is precisely in the crucial early and middle phase that the resistance band does not work, regardless of which band you use.

 

Flywheel training

How about flywheel training? The resistance of the flywheel automatically adjusts to your muscle strength. Accelerating a flywheel takes power. You try to accelerate the flywheel throughout the movement. The more you try to accelerate the flywheel (which works better with a good overlap between rope and rows of people) the more challenging it is. That is why the resistance of the flywheel is a copy of the muscle force-length relationship. As a result, you challenge your muscle in all phases of the movement. This applies not only to the concentric movement, but also to the eccentric movement.

 

Summarized

Resistance bands do not create resistance in the initial phase of your exercise, which produces 3x more effect than the final phase. Where the resistance of the band increases towards the final phase of the movement, your muscle strength decreases. Flywheel training challenges your muscle throughout the movement and is therefore many times more effective. Apart from the eccentric advantage of flywheel training. Read more about flywheel training here or get started right away!