Indeed. In general, RSIs like tennis elbow are caused not just by the repetitive motion, but by the fact that doing the motion repeatedly instead of a wider variety of motions causes certain muscles to become over/underdeveloped, resulting in unbalanced/incorrect tension on the affected tendons and more strain than the overdeveloped muscles would normally see during other motions because they end up doing more of the work than they're supposed to. Doing a variety of light exercises can help even things out.
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