A few months back, I posted an entry about the Zip Curveball Trainer and why it is an awful product. At the time, I was aware that the regular Zip Trainer existed, but I assumed it couldn't possibly be worse than the Zip Curveball Trainer. I finally read about it, and I was dead wrong.
The product is "designed" to promote wrist flexion as a proper part of a powerful pitch release. Like the Zip Curveball Trainer, though, the Zip Trainer teaches it backwards. The device actually trains its users to extend their wrists as they prepare to release the ball.
One advantage of increased strength in the extensor muscles is that the muscles will be able to handle greater loads during deceleration. This means that after using the Zip Trainer, a pitcher will likely develop faster, more powerful wrist action because the forearm will be better conditioned to slow the hand down after the pitch is thrown.
So why is this bad? When a muscle or group of muscles contracts during joint action (flexion or extension), the brain prevents the opposing muscle(s) from contracting simultaneously. This is called reciprocal inhibition. This means that while the extensor muscles are extending the wrist, the flexor-pronator mass can not contract to support the ulnar collateral ligament.
Because this device teaches wrist extension prior to pitch release, pitchers who use this device "properly" place themselves at an increased risk for UCL injuries.
But wait! There's more!
The product page also offers tips on how to use the Zip Trainer to throw a slider. By moving the finger loops onto different fingers, the Zip Trainer can also teach its users to throw sliders with supinated releases.
Supinated releases do not protect against the forearm flyout flaw that is present in the arm action of most pitchers with traditional pitching mechanics. When unprotected, this flaw causes the back of the elbow to "slam closed." The collision between the olecranon of the ulna and the olecranon fossa of the humerus irritates cartilage and leads to irregular bone growth (lengthening of the ulna, bone spurs, bone chips, etc.).
To have a look at this questionable product for yourself, click here, but please, don't buy this.
Do you know of another stupid pitching product out there? Tell me about it.