One of the challenges with applying strength and conditioning literature to physical therapy practice is the differences in participant populations. Many exercise science studies use college students, providing a small sample size of 18-24-year-olds with little to no comorbidities. This population is not representative of most patients in our clinics. The underlying exercise principles remain the same in all people, but there are more complicating factors to account for.
PTs need to consider the influence of comorbidities, pain, fear, catastrophizing, previous education from medical providers, medications, and current activity limitations. Some of these are relevant in the personal training and sports performance spaces as well, but to a lesser extent on average. This perspective takes those factors into account and attempts to blend the rehabilitation with the strength and conditioning worlds.
When prescribing exercise, we are often balancing graded exposure with graded activity. Each exercise does not need to induce overload and improve strength, power, endurance, or muscle mass. Those are vital components when the time is right. I do want to express caution with the common emphasis on "excessive" demand and injury risk. We don't have any data to suggest lumbar flexion when squatting or lifting is dangerous. The same with knee valgus or end range positions.
Just because something places more stress or strain on tissue does not mean it is harmful. Our exercise selection and the narratives we place on them are powerful and influence future behavior outside of the clinic.