I'm 40 years old, 6'3" and 220lbs.. I started working out on a 100lbs heavy bag about 2 years ago. After about 4 months of 1/2 hour a day, the back of my hands started hurting. It got to the point where I could not even hold a tennis racquet. I went to PT and they said it was tendinitis. I laid off for a year now and just started again 2 weeks ago with a portable heavy bag (water filled bottom) as I thought it would be less resistance. The back of my hands just started to hurt again. My wrists are fine and my knuckles are fine. It's the tendons that hurt. I wrap and use bag gloves. Any suggestions?