The<unk><unk><unk>  (UCL) can become stretched, frayed, or torn through the repetitive stress of the throwing motion. The risk of injury to the throwing athlete's UCL is thought to be extremely high as the amount of stress through this structure approaches its ultimate tensile strength during a hard throw. This injury is associated with baseball, although it sometimes appears in other sports. Compared to athletes who play other sports, baseball players are at higher than average risk of overuse injuries and injuries caused by early sports specialization among children and teenagers. While some sources say that an individual's style of throwing or the type of pitches they throw are the most important determinant of their likelihood to sustain an injury, the results of a 2002 study suggest that the total number of pitches thrown is the greatest determinant. A 2002 study examined the throwing volume, pitch type, and throwing mechanics of 426 pitchers aged 9 to 14 for one year. Compared to pitchers who threw 200 or fewer pitches in a season, those who threw 201–400, 401–600, 601–800, and 800+ pitches faced an increased risk of 63%, 181%, 234%, and 161% respectively. The types of pitches thrown showed a smaller effect; throwing a slider was associated with an 86% increased chance of elbow injury, while throwing a curveball was associated with an increase in pain. There was only a weak correlation between throwing mechanics perceived as bad and injury-prone. However, because there are many effective styles of pitching, "incorrect" throwing mechanics can be difficult to define and determine. One of the most common denominators among virtually all pitchers is "reaching back" with the throwing arm prior to release and follow-through. This repeated "reaching back" motion is believed to be a major contributing factor in UCL injuries, as it stretches the<unk>  in an unnatural manner and direction. Simply raising the pitching arm up and bringing it forward with a complete follow-through produces the same levels of spin rate, velocity, movement, and location while helping to protect the UCL from unnecessary injury. Research into the area of throwing injuries in young athletes has led to age-based recommendations for pitch limits for young athletes. A 2016 study explained 22% of the variation in those needing<unk> , citing handedness, standard deviation of release point, days lost to arm and shoulder injuries, previous<unk> , number of hard pitches, ERA-, and age as the known risk factors. In younger athletes, whose epiphyseal plate (growth plate) is still open, the force on the inside of the elbow during throwing is more likely to cause the elbow to fail at this point than at the<unk><unk><unk> . This injury is often termed "Little League elbow" and can be serious but does not require<unk> g the UCL. Increasingly often, pitchers require a second procedure after returning to pitching—the periods from 2001–2012 and 2013–2015 both saw eighteen Major League pitchers receiving the procedure a second time. As of April 2015, the average amount of time between procedures is 4.97 years.
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