How many times have you heard, “curveballs place more stress on the elbow than fastballs, ” or ” throwing curveballs will ruin a young kids elbow,” or something similar from a coach or parent? I imagine quite a bit.
Research paints a different picture though. In a research article that Dr. Glenn Fleisig and Dr. James Andrews published in Sports Health in 2012, they cited six studies that either showed a curveball actually places less or equal varus torque on the elbow than a fastball; or pitchers who began throwing the curveball at an age 13 years old or younger did not have any greater injury risk than pitchers who started throwing it at an older age. Rather, the primary cause of youth elbow injuries was found to be overuse: pitches per game, innings per year, and months pitched per year. Pitching while fatigued, pitching for two different teams during the same competitive season and poor pitching mechanics in general were also found to contribute to youth elbow injuries.
You can read the full study here:
A more recent literature review regarding curveball use and youth injury risk by Grantham et al. in 2015 looked at 10 studies related to curveball biomechanics and 5 studies related to pain or injury incidence while throwing curveballs. Of the 10 biomechanical studies, none of them reported more increased torque at the shoulder or elbow when throwing a curveball versus a fastball. Three of the five pain related studies reported no relationship between curveballs and shoulder/elbow pain while 1 study did report more shoulder pain from thowing a curveball versus a fastball.
You can find the study here:
Generally speaking, these studies have shown velocity of the pitch, not type of pitch, is what results in higher levels of stress at the elbow and shoulder.
There is however, a non-peer reviewed thus non-published in house study done on a small sample size of higher level pitchers by Driveline baseball in Seattle, Washington that found some interesting data when comparing fastballs to off-speed pitches. Initially their findings supported what the other research studies have found: fastballs placed more torque on the elbow than curveballs. However, when they normalized for velocity, the curveballs actually had a higher stress value. There were 8 pitchers in the study and the columns are broken down into fastball vs curveballs for each pitcher. The original stress numbers are in those columns. If you scroll to the right, you’ll see the normalized for velocity stress numbers.
Here is the data chart from their study. Driveline Fastball vs offspeed data
Obviously 8 pitchers is a very small sample size and the velocity was normalized via a math equation. What’s that’s saying is all things being equal, it’s possible curveballs place more stress on the elbow than fastballs, but again velocity is the big variable here.
It’s pretty clear the myth that curveballs are the reason for youth pitching injuries can actually be put to bed. It’s also clear there are numerous factors that result in youth pitching injuries and curveballs may certainly be one factor depending on the mechanics used to throw them. It’s certainly considered by many to be within best practice to limit introducing curveballs to youth pitchers before they have established proper pitching mechanics. Most importantly, all the Physical Therapists, orthopedic surgeons and athletic trainers I have every heard speak or have read regarding the topic of youth baseball injuries place overuse well above curveball use as the biggest issue in youth baseball. In fact, here is a quote by Dr. Glenn Flesig, “it wasn’t the invention of the curveball that increased risk, it was year-round baseball.”
Don’t miss the forest for the tress. Throwing with greater velocity, throwing more than 80 pitches a game, pitching more than 8 months a year, pitching for more than one team in the same competitive season, pitching while fatigued and pitching with poor mechanics are all more related to elbow injury risk than throwing a curveball and are all what I dare say to be much bigger issues in youth baseball than curveball use.