When Should I Let My Child Start Throwing Curveballs?

With the Little League World Series being aired on televisions around the world, 12 and 13-year-old athletes from numerous countries around the world are competing to win the championship, claiming the title as the best little league team in the world. Every year I see these kids throwing huge breaking curveballs that dazzle and receive high praise from announcers. But should these youngsters really be throwing curveballs? Aren’t curveballs bad for your arm?

The short answer is…maybe.

The most important thing to consider for youth pitchers when throwing a curveball is whether your child has good throwing mechanics and enough body strength to properly pitch a curveball. Generally speaking, a pitcher between the ages of 12 and 14 should be able to safely throw a curveball, so long as proper mechanics and coaching input are present.

Let’s look at some important topics surrounding this question:

  1. Are curveballs actually dangerous to the arm?
  2. Proper pitching mechanics for throwing a curveball
  3. Other considerations

Are Curveballs Bad for the Arm?

This has been a very controversial subject, with many parents, coaches, and players arguing with great reasoning their particular view of this subject. In the youth baseball world, a curveball that is thrown incorrectly repetitively can possibly lead to injury. However, so can improper hitting mechanics or improper sliding technique into second base. It is most important when considering whether or not a curveball is bad for a ballplayer to throw, to look at the pitcher’s mechanics when throwing this pitch in comparison to their mechanics throwing another pitch, such as a fastball.

In the major leagues, the curveball has made somewhat of a resurgence, with a huge portion of all MLB pitchers throwing some variation of a curveball. Certainly, if a curveball was detrimental to the arm, there wouldn’t be so many professional athletes throwing it, right? Right. The nearly perfect mechanics that MLB pitchers use when throwing curveballs, as well as every other pitch, is the reason why they are in professional baseball, and why some of the best pitchers also have fairly long careers.

Research conducted by the American Sports Medicine Institute on curveball throwing pitchers found that the risk of a youth pitcher being injured by throwing a curveball occurs no more often than that same pitcher being injured by pitching a fastball. Further studies found that there was a slightly increased risk of pain for young pitchers who throw a curveball versus pitchers who only throw a fastball. Yet the most impressive result of the studies found that the increased risk of pain jumped significantly when pitchers reported their arm to be “tired”.

Regardless of whether or not a curveball is harmful to the youth pitcher, a tired arm is much more likely to be hurt than an arm that is feeling good. That is why many youth leagues, including Little League Baseball, require that teams track their pitcher’s pitch count meticulously and have rules limiting the number of pitches that can be thrown by one pitcher in one game, as well as rules outlining the necessary rest days that are required before that pitcher can return to the mound. 

Considering that your child will hopefully be pitching with an arm that is feeling fresh and strong, let’s look at some of the aspects of proper pitching mechanics BEFORE your child starts throwing breaking balls.

Proper Pitching Mechanics

In order for your child to start throwing a curveball, you want to make sure that they are consistently exhibiting proper pitching mechanics. The crazy thing about pitching is that there is so much information out there about how to properly pitch, so many people that spend their whole careers studying the pitching motion to try and create the best and least intrusive pitching motion, yet somehow pitchers still end up succeeding with pitching motions like this:

Image 1.

So you might be asking, what should I teach my child?

1. Use Your Legs

If you have ever seen ESPN Magazine’s yearly Body Issue, professional athletes are photographed doing their sport’s action, in the nude. I have always been fascinated by this yearly issue because you can really see which sport-specific muscles the athlete has built up. Year after year, MLB pitchers are featured in this issue and their tree trunk legs consistently catch my attention. It’s hard to notice when you seem them on television because baseball pants are usually baggy, but it is remarkable how muscular these pitchers are. The mechanics of pitching all start with good use of the legs. Teaching your child to load up on their post leg and EXPLODE off the rubber is crucial. In athletic training, this is known as a plyometric movement: a power movement where there is a load up phase as well as an explosion phase that uses the energy built up by the load phase to explode into the power phase. Teach your child to pause momentarily during their leg lift and explode off of their plant leg. 

2. Stride Length

In the figure below (Image 2) you will notice that the figure takes a long stride. This is another important part of having good pitching mechanics, and again it starts in the lower body. Encouraging your child to explode off the plant leg will naturally increase their stride length. Having a short stride can often put more stress on the upper body to compensate, causing pitchers to tire easily, therefore increasing injury risk.

3. Arm Angle

Despite my previous example of the submarine delivery pitcher (Image 1), you want to make sure that your child’s arm angle is no lower than ¾ (three quarters arm angle is halfway between 90 degrees at the elbow, and the elbow being completely straight). Keeping the arm at a higher angle allows for the pectoralis major (chest muscle) to do more of the heavy lifting, pulling the arm down, as opposed to using more anterior deltoid (shoulder) muscle with a lower arm angle. The general idea for pitching biomechanics is that you want to load the bigger muscles with more work, as they are able to handle greater repetitive forces. Muscles in the legs, core, and chest are bigger and can handle much more than smaller muscles in the shoulder and arm.

Image 2.

4. Don’t Drop the Elbow

If your child’s elbow is dropping lower than their shoulder in their normal throwing motion, there is a reason for concern, even in throwing pitches like the fastball. Again, dropping the elbow will distribute torque on smaller muscles in the elbow and shoulder. When young athletes start to throw curveballs, dropping the elbow is a common thing that occurs because it allows pitchers to get more spin on the pitch. The pitch might look really nice coming out and could even be a good pitch putting hitters away, but it is a bad habit that can get your child into injury trouble later on.

5. The Grip

When your child finally comes to a point where they have good pitching mechanics, it is important to introduce the proper curveball grip. The curveball is thrown using mainly two fingers: the middle finger and the thumb (Image 3). When coming out of the hand, the middle finger is situated on top of the ball with the thumb on the bottom, palm facing inward. The release is a snap of the wrist with the thumb and middle finger switching positions to finish with a hand position similar to as if you just cast a fishing line (Image 4). 

Image 3.
Image 4.

Other Considerations

Your Child’s Strength

As mentioned in the previous section, having proper mechanics is of huge importance, however, ensuring that your child has sufficient strength is also very important. Building up muscle in the right places, focusing on lower body and core strength will help in guiding your child’s pitching mechanics in the right direction. If the correct muscles are strong and active, mechanics will follow suit.

Many children tend to hit puberty at around the ages of 12-14 and start growing in height as well as muscle. This is one main reason why I would recommend for my child to start throwing a curveball at this age, assuming sound mechanics. I began throwing a curveball when I was 13, as I was in my last season on the 60-foot base paths and I was a strong kid for my age.

Changeup Pitch

The main purpose of adding other pitches besides a fastball is to get the hitter off balance by either decreasing the speed, making the ball curve or drop, or a mix of the two. The curveball is the pinnacle of creating both speed change and ball movement, but before being able to master both, you should focus your child on mastering a pitch with just speed change, the changeup. Encouraging your child to work on throwing changeups as the first pitch they learn after a fastball is a great idea because it can be more easily thrown and has equally good results. When your child is able to pitch both a fastball and changeup with accuracy, then you can begin the process of learning the curveball.

Additional Information

For a really great video by MLB network on this topic, check out this informative Youtube video featuring pro-baseball legend Al Leiter:

Related Questions

How many pitches should my child be throwing per game? How much rest should they be getting?

Here is a great resource by Little League Baseball that shows the recommended pitch count maximum and how much rest should be observed based on the number of pitches thrown. The chart indicates N/A for categories that exceed the maximum pitch count recommended.

My child has started throwing a curveball with his buddies and wants to throw it in games, but his mechanics do not look good. What do I do?

First and foremost, talk to your child about it. Let them know that they need to work with Coach on improving their pitching mechanics on their fastball. If they want to keep throwing it anyways, talk to the coach about the possibility of keeping him off the mound until he can do it properly. You child might not like it but it is much better than getting them hurt.


Flesig G, Barrentine S, Zheng N, et al. Kinematic and kinetic comparison of baseball pitching among various levels of development. J of Biomech. 1999:32,1371-1375.