Mike Boyle, one of the nation's most respected strength coaches, reiterates that athletes should avoid any exercise that's performed behind the neck. He says, "Extremes of abduction and external rotation can be really stressful on the shoulder joint."
To make matters worse, many people have difficulty getting their arms overhead in the first place. As you raise your arms overhead, does your back arch and ribs flare out? If so, you fall into this group. "Most people have difficulty getting their hands overhead without compensating," says Boyle. "Combine this with a lack of external rotation and you have a recipe for disaster."