Generally speaking, I believe a baseball pitcher should be about 15 years old before throwing the curve ball in game situations. It is not a matter of being able to teach the pitch to a young pitcher - most kids can throw it. But is the youth pitcher's arm capable of handling the stresses of the pitch? Most are not.
Factors To Consider On Pitching Curveballs
Has the pitcher reached puberty; how developed are his bones and connective tissues? - A young pitcher’s connective tissues, his tendons and ligaments, are not as strong or as securely attached compared to a mature pitcher, thus there is a greater risk of injury.
Is the pitcher in the middle of a major growth spurt?
How well developed are the biceps, triceps and forearm muscles? - A young pitcher needs arm muscle strength to help stabilize and control the forces on the elbow joint during the acceleration, release and deceleration phases.
Has the pitcher been taught to throw the curve ball properly?
How many curve balls (percentage wise) is he throwing in games?
Is the pitcher experiencing any arm, mainly elbow, problems from throwing the curve ball?
Most of the stress from throwing the curve ball is on the ligaments of the elbow, the biceps and forearm muscles. Since the hand and arm speed is slower than on the fastball and slider, and the elbow leads longer, there is usually not as much stress on the shoulder joint as on the fastball.
Regulation Pitching Distance
Another major reason I have concerns about teaching the curve ball to 13 and 14-year old pitchers is that they already have more than enough physical stress having to pitch from a 60-foot 6’-inch mound versus the 46-foot Little League distance.
To add a breaking pitch at this age only compounds the physical exertion on the arm and body.
Most young pitchers' hands and fingers are smaller and shorter, so the youngsters have problems gripping, controlling and releasing the pitch properly. This often causes the hand, wrist or elbow to be out of proper position during the acceleration and release phases, which can lead to injury.
Also when a young pitcher learns to throw a curve ball and has some success with it, he often "falls in love" with the pitch (throws it too often) and he will never really develop arm strength, hand speed, and fast ball pitching velocity.
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