At the time of writing, there still exists much debate as to the absolute strength benefits of unstable training, such as that performed on a suspension trainer. Part of the reason for the conflict is that there appears to be very definitive evidence to support both sides of the argument.
So does it work or not?
The answer, like many things is: it depends.
The reason for this lack of a definitive response is that people can be weak for different reasons:
- Lack of contractile strength
- Low work capacity
- Low skill
- Poor efficiency
The latter is the one that unstable training really seems to enhance.
Structural balance is the concept that there exists equilibrium between the body’s ability to produce force and the tissue’s ability to tolerate or control it. If the force generation potential is high, but the tolerance or control is low, then the nervous system detects this and limits force profuction.
An example of this would be an individual with stagnant progression on the bench press. If the muscles that stabilise the shoulder during this exercise are proportionally weak, then the nervous system will typically limit progress on this exercise until the balance has been restored. The occasions when this limiting of force production fails to occur are typically evidenced by injury. Ballistic repetitions are a perfect example of the potential to bypass your body’s natural limits and also the potential risks of doing so.
So how does unstable training help with this?
Unstable training results in different recruitment patterns in the muscles that stabilise movement. There also tends to be a higher level of recruitment, assuming that loads are matched. This means that the limiting factor on these exercises is often not the prime movers, but rather the muscles that facilitate the movement.
Obviously, it’s not enough to assume that simply performing chest presses on a suspension trainer will automatically improve your bench press. But, if the reason your bench press has stalled is because you lack the requisite stability at the shoulder, then it may be a viable option.
Likewise, a client that has poor knee stability and as a result, struggles with certain leg exercises, may find that squatting on a Bosu or wobble board helps improve knee stability. If their ability to squat is due to poor coordination, performing a squat using a suspension trainer may help to remove the demands on the upper body positioning and thereby allow them to focus more specifically on movement at the knees.