Just because they market bands to this age does not mean they will help a youth player. 8-12 years old.... I mean dang man what's the point? More velo at 10 years old ? .... play baseball,go fishing, camping, whatever other sport he wants to try. Kids at this age are growing and changing so much , you are still a ways from puberty.
JCG respectfully I cannot disagree more with your assessment of using these bands to help a youth pitcher for warm up and strength. They can warm up by be tossing and running.... pitch count and be done for the week.
Please at 8-12 years old do not have a pitcher do band work... you have to know your body, have an understanding of how your body works and be mature enough to physically to do these exercises. We have no idea who this player is his body or anything else about his medical history.
Learn to pitch to batters, learn to spot the change up and fast ball... have a pitch count and stick to it win or lose, then go to the Dairy Queen after the game. 9 years old, sheet I have jeans older than that.