Out riding today getting a new set of bars adjusted properly and i began to notice while performing nose wheelies as well as other simple techniques that the mussels on the palm side of my thumbs were beginning to be really sore with out a lot of riding or hard effort being used for what i was doing. I have been wanting to build up some strength in my hands in general. What can i do?

Use those squeezee things that you can find in sports shops. They usually sell in pairs so I leave one in my car.

For forearm strength tie a bit of rope to a brick and wrp the other end round a peice of broomstick and try to wind the brick up the broomstick and then down, then up..you get the idea?

If you want to buy a gadget get a powerball

of course you cut out all this training/practicing malarky and get a powerband