How important is your thumb during an arm wrestling match? Well ... not that important ... but it is still important! Think about it: When you are trying to get out on your opponent's fingers, you have to to clamp down on their fingers in multiple different positions while you are move - in stages - out on their fingers. One half of that clamp comes from your fingers, but the other half comes from - you guessed it - your thumb!
But training your thumb is not as easy as it sounds. Almost without exception, no "traditional" exercise you perform does much, if any, training of the thumb. Even so called hand exercises, like Heavy Grips, train the thumb to only a very limited extent.
So the question then becomes: how do you do train your thumb? I have come up with a device (pictured below) that will make your thumbs super strong.
How It Works
The machine is very simple (and very home-made!). It operates on the exact same principle as a teter-totter. It acts in a similar way to a hand gripper, except that rather than one of the sides of the hand gripper being anchored in place by your palm, it is anchored by your thumb. Because of this, you will not be able to use nearly as much weight as you would if your thumb was not involved.
See the pictures below for more details.
One word of caution: Be sure that you do not use too much weight, as you do not want to rip any of the delicate tendons in your thumbs!