i was wondering whether warming up with a penny ball will have any negative effects on your arm. The good part is there was a 5-7mph increase on my fastball the first few innings
Obviously, it is very heavy and that will put strain on your arm. Long term effects would be ligament and tendon damage in the shoulder and elbow.
The sad thing is the penny ball wont really help your velocity. By training the arm to throw a ball which is heavier than normal, you are changing the nature of your mechanics. Also, you have to slow down the motion of the arm in order to throw the heavier ball, so the longer you use the penny ball, the slower your pitches will be.
The overload principal as it applies to baseball does work, but with more reasonable weight differences. Using a ball that is slightly heavier than regulation, say 6-8 oz., and mixing it in with the 5oz regulation baseball and even a 4oz ball is much more effective. This way you get the benefit of increased power from the heavier ball, while also getting faster arm action from the lighter ball. There shouldn’t be any noticeable change in mechanics either.