‘Arm Fatigue’: What is it?

Rumors are running around that Trey Lance is dealing with “arm fatigue.” This brings up doubt for the potential fantasy superstar and projected starter for San Francisco. As a player known for utilizing his legs and questioned on his ability to pass, any news regarding a shoulder issue will make the fantasy community question Lance’s abilities. Based on the limited sample from games played last season, some have described his throwing as ‘wonky.’ So what exactly is “arm fatigue”?

‘Arm fatigue’ or ‘dead arm’ is a term used in baseball, specifically with pitchers. The throwing motion places extreme forces on the shoulder, especially during the follow-through phase. With high repetitions during practice and games, arm fatigue can occur, causing weakness, “heaviness,” and pain in the arm. Along with these symptoms, the thrower may lose ball speed and show poor accuracy.

An image showing the amount of torque placed on the shoulder during the throwing motion.

As mentioned above, ‘arm fatigue’ is an overuse injury that may occur after many repetitions. As a player throws more and more, the rotator cuff becomes fatigued and may lead to damage. During the offseason, quarterbacks are known to work on their throwing motion and may tweak things to improve their throws. Lance has admitted to changing his grip on the football due to a thumb injury he was dealing with for most of last season. When working on a new throwing motion, it is not uncommon for a player to experience this fatigue. With a new throw comes altered arm motion, different muscle recruitment, and increased strain on the arm.

Despite multiple sources hinting at Lance’s arm fatigue, there is likely little to worry about coming into the season. Lance’s teammate Brandon Aiyuk recently joked on Instagram, “The only three throws from the day, his arm got fatigued after that…”. Clearly, the people closest to Lance are not worried about his arm, nor should you be. We will continue to monitor this situation throughout the offseason. Should anything change, we will be sure to reflect these changes in our rankings.

Sam Webb, PT, DPT, SCS

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