As summer ball starts, here are recommendations from the American Sports Medicine Institute:
Watch and respond to signs of fatigue (such as decreased ball velocity, decreased accuracy, upright trunk during pitching, dropped elbow during pitching, or increased time between pitches). If a youth pitcher complains of fatigue or looks fatigued, let him rest from pitching and other throwing.No overhead throwing of any kind for at least 2-3 months per year (4 months is preferred). No competitive baseball pitching for at least 4 months per year.Do not pitch more than 100 innings in games in any calendar year.Follow limits for pitch counts and days rest.Avoid pitching on multiple teams with overlapping seasons.Learn good throwing mechanics as soon as possible. The first steps should be to learn, in order: 1) basic throwing, 2) fastball pitching, 3) change-up pitching.Avoid using radar guns.A pitcher should not also be a catcher for his team. The pitcher-catcher combination results in many throws and may increase the risk of injury.If a pitcher complains of pain in his elbow or shoulder, discontinue pitching until evaluated by a sports medicine physician. Inspire youth pitchers to have fun playing baseball and other sports. Participation and enjoyment of various physical activities will increase the youth's athleticism and interest in sports.
The source link also includes pitch count recommendations:
http://www.asmi.org/research.php?page=research§ion=positionStatement
