In baseball, injuries to the throwing arm occur often. Throwing a baseball is an extremely unusual yet skilled movement that requires a highly coordinated and synchronized motion which undoubtedly places severe stress on the shoulder and elbow (among other areas). Having said that, it may not be feasible to offer a solution to completely prevent throwing related injuries, but rather highlight a few ways we can minimize the damage.
Throwing Mechanics - Improper throwing mechanics will likely lead to inefficiencies that the body (usually the arm) tries to make up for. The hard part is identifying the problem, especially if you don't currently experience any pain. You will most likely need your coach (and maybe some video) to help you identify faulty movements in your motion. * TIP* The best way we try to fix this is by allowing the athlete do what is natural to them and from there we make simple changes (by way of coaching cues) within that motion that will better allow them to: 1) maximize their body 2) put them in optimal positions to effectively create and accept force and 3) coordinate, control and repeat movements (even changes within their exercise program can immensely help once we identified the problem).
Conditioning - Your level of conditioning will greatly influence your ability to repeat your mechanics. As fatigue sets in, your mechanics will surely break down and put your body in vulnerable positions. *TIP* Make sure you approach conditioning in many different creative ways to ensure that you are preparing the ENTIRE body for the repetitive contractions, not just the legs (if you are just running poles, consider a new strength or baseball coach).
Strength / Stability - Stronger muscles will be able to handle the repeated stress, and efficiently contract to create and control movement and force (a common example is the strength to slow down the arm). Any major weaknesses will likely alter mechanics and/or create compensations (which increases the rate of injury). Unstable joint complexes and muscles will not be able to function effectively and it is likely your body will not be in an optimal position to throw. *TIP* Make sure you are always actively trying to increase/maintain strength and stability in all the major/supporting musculature and joint complexes (don't neglect the little muscles and stability drills).
Mobility / ROM / Flexibility - Due to the repetitive microtrauma the muscular system experiences when throwing, it is not uncommon for the body to feel tight or restricted after. *TIP* it is crucial to do mobility, ROM and flexibility exercises as necessary (specific to the individual and what they are experiencing) to ensure functionality.
Rest - If you don’t give your body the adequate rest to repair and recover, it will be hard not to get injured. *TIP* Don't try and be a hero, rest is okay.