"The Spider" is controversial due to what some have called a potential for carpal tunnel symptoms that may result. I'm not sure about that, but there is plenty of reaching on the lower frets with this technique.
Gripmaster is available in different tension models (colors).
The spider is only no more controversial than someone who just decides to run a marathon tommorow with no training...expect trouble, not controversy. Spider and one finger one fret, are exercices to work towards, not for anyone to just start. These two skills get developed and blended in to a players development.
As does finger picking and freting chords...you develop towards them.
The gripmaster..it does not matter how many tensions there are, they works the wrong muscle groups. Anything that develops the hand to close is not for bass. Muscles work in what we call antagonistic pairs. Muscles can only pull, so for every movement you get you have an opposite movement.
So as you develop the hands flexor muscles with a gripmaster, what is developing the opposite movement or the extensors?
Now if you need to move your fingers in both directions to "put on" and "lift off" then you are only making it easier to put on and harder to lift off. The muscle action will be developed to preference one particular movement ( the closing of the hand by the flexion of the fingers) toward making a fist or to make a grip or hold.
Part of the problem with hands is that full movement is never really used so is never developed. Yes we open and close our hands but we never full open them to there full extent, so the muscles become "shortened".
That is a phrase to describe a muscle that never ever gets its full range of movement, thats why athletes stretch muscles to give them a full range of movement and to loosen them up before and after use of them.
When you hold something you hold it with the full extent of that muscle group. Because the object you hold offer resistance, the hand and finger are now restricted from closing any further, activate the muscle more and the hands or finger do not close any more, but the tension builds in to the hand as a grip. When you release you do not extend you fingers fully to release, you only extend enough to to let go to the object, and thus the extension stops. The extensors to release never got the same use are the flexors to grip, because once you let go you cannot let go more, or let go harder, but you grip more or harder to any object you handle.
Because your hands always get more opportunities in modern life to allow the fingers to grip and hold, flexor groups get more than enough exercise, but extensor never do, unless it is pre-determined by the user, the user make a point of extending them. Now simply opening them and holding, is a stretch. But the fingers can open and spread, they can move towards and away from each other when spread in a side ways motion. There full range is when they are spread and open. Where as a grip is fingers tight together, no movement, no dexterity, actually the opposite. The fingers act as a fibre with each other to make one big fibre....for strength and stability...lack of movement. Similar to the way a rope works, the fingers combine to make strength.
Again this closed hand position is no good for playing bass, but a gripmaster will help develop it.
As i said, the thing about any exercise is knowing when to stop and let recovery happen...exercise is not for all, as is playing a bass, but thats a different subject all together.
