The two main causes of injuries, both acute and chronic, are poor mobility and poor technique. This applies equally to masters, youngsters, and those in between. Poor mobility esp. in the hips, shoulders and upper back may cause technical flaws in many movements from the simple to the complicated. A lack of understanding of the required movement skill, or a preexisting misunderstanding of an exercises’ correct execution, will lead to ugly lifts. Although all populations suffer from these flaws, masters athletes may suffer more frequently. The older athlete’s prior injuries and habits of a lifetime may lead to postural faults along with their concomitant mobility restrictions and compensatory movement. Prior coaching (high school coach from years ago) may lead older (mostly male) athletes to think they need no technical instruction.
Neither high reps nor high weight workouts are dangerous if performed with awareness and technical proficiency. If one insists on performing them in spite of poor mobility and/or technical insufficiency, injuries, not conditioning, are the probable outcome. In order to minimize the chance of injury all athletes across all ages need better postural awareness, regular mobility work, and frequent technical practice.