Been working on my hand strength quite a bit this past week. I'm playing more SRV than usual, and I've probably mentioned that I want to incorporate his power, more than anything else, into my own playing. And it's not just about finger calluses. Stevie had huge hands and Popeye forearms, easily twice the meat between elbows and fingers that I have. So I need to beef up.
Enter pictured exercise tools. I got a simple gripper and a Dyna-Flex PowerBall. I use the gripper for about 5 minutes, starting with 1 squeeze with each hand, then 2, 3, up to 15, and back down. My hands tire in strange ways. My right hand feels stronger than my left on the way up and weaker on the way down. It makes sense that my grip is stronger in my dominant hand while my fretting hand has more stamina, but I didn't think it would be so obvious.
I use the gyroscope more for therapeutic purposes than building strength. I imagine it loosens a lot of tiny muscles that are otherwise only used for guitar. Definitely helps keep the tendinitis away.
Now I'm just trying to establish a permanent habit of using these guys a couple times every day. Both are great for taking care of morning fatfinger.