I love the wrist roller, but ive also done lots of palms up and palms down wrist curls, behind back wrist curls, leverage bar curls and twists etc. I have weak wrists so i have to work extra hard to strengthen them.

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Im sure a strong forearm would help a boxer greatly by reducing the amout of injuries to the wrist.

If you're prone to carpal tunnel you will have to be cautious, but id image that it could help if you dont over do it. Im not a doctor though so this is only speculation.

If you are going to train your forearms, use high reps (15-100 per set), use a variety of exercises to make sure you dont cause an imbalance and make sure you use a full range of motion and never cheat. You dont want to injure your wrist (this is especially true for a boxer).

Bruce Lee trained his forearms all the time and used all kinds of equipment and exercises includingthe wrist roller, and he had the best forearms ever imo.