I had no idea what a dynamometer was until my brother started explaining his physical therapy treatment to me.
He is a carpenter by trade, and builds houses for a living. He is right handed and had an injury to his right hand while at work.
Since he needs full use of his hands in order to make a living, it was important that he get the right treatment.
He told me he was using a hand held dynamometer for many of his exercises. He had to do quite a few repetitions a day and at first these were very painful and hard to do.
As time went on and he began to get some of his strength back, they became easier to do. He was eventually able to return to work, but it was a few months before he had full strength in his hand.