grip with three fingers - why?

[dakotajudo]

The anatomy of the forearm is such that the three highest digits (pink, ring, middle fingers) fuse to a common tendon connecting to flexor digitorum profundus - the main mucle that flexes the finger. The index finger also attaches to this muscle, but via a separate tendon.

These tendon run straighter, through the carpal tunnel, if only three fingers are engaged; the index finger causes the tendon group to deviate. This may weaken the grip a bit.

The tendon to the thumb is also somewhat bent as it goes through the wrist.

Try this - make a fist with just the 3-5 fingers. Feel your tendons in the wrist with your other hand. Add your index and thumb into the grip, and feel how the tendons shift.

See http://www.bartleby.com/107/illus415.html or http://www.emedicine.com/plastic/topic296.htm

With a gi, I prefer the three finger grip; but for no-gi, I like to grab the arm by pinching with thumb and forefinger, just above the epicondyles of the humerus (bony projections just above the elbow).

PS. I seem to remember that some wrestlers prefer the four finger (no thumb) grip when working an arm. Not so sure why.

[HoratioHooah]

Just to clarify, what I was saying about using only the lower two fingers to grip was only in reference to judo nage-waza.

[dakotajudo]

That so totally finnaly explains why a trick I learned to deal with "power handshakes" works so well. I have really scrawny forearms and so I can never match a lot of guys grips but somewhere along the line I learned that if I sense one of those super crushing alpha male dominance moments coming on all I have to do is extend my index finger in the middle of the shake and kind of ...I dunno..project intent out through it and it doesn't let me squeeze real hard or anything but it seems to completely "immunize" me against getting my hand crushed.

There is similar trick I've been taught (though I don't put much faith in it, to be honest) that involves using the index finger, in such a handshake, to put pressure on the tendons of the (opposite) forearm.

If I were to postulate a physiological mechanism, I would include the stretch receptors in tendons, that act as a failsafe - high tension in a tendon feeds back to the muscle, inhibiting muscle contractions and decrease tension on the tendon.

Tendons are commonly more limiting in generating muscle force than the muscles themselves. This is why people under physical stress or competition can tear tendons - mental drive overcomes the safety system.

On the other hand, the "project intent" comment reminds me of aikido, where I've used the mental image of projecting to maintain good forearm and wrist alingment. That may be what's protecting your grip.

[Teh El Macho]

No.
Weightlifters grips vary, and most are mainly overhand finger or palm grip.

`~/

Even FMA,
lightly with thumb and forefinger while twirling, but, with lower fingers otherwise.

Dito. I used to bench press using the thumb to grip the barbell, and every once in a while, I would develop pain deep in my palms, somewhere around the metacarpals. Then, I was told to use a palm grip (not using my thumb). It gets harder to control the barbell, but I've never had pain problems in my thumbs ever since.... just an anecdote a bit off-topic.