Dr. Jonathon Sullivan responding to a query concerning possible negative outcomes from strength training:

Where is your peer-reviewed, properly controlled data to indicate that progressively increasing one’s strength with heavy training causes an inflection point to the negative in either performance or “health” in populations? And what is the consensus of the data as to exactly where this inflection point will occur for any individual or population?

Well, it won’t be found here:

In a study lasting nearly two decades involving 8,762 men aged 20-80 it was found that, “Muscular strength is inversely and independently associated with death from all causes and cancer in men, even after adjusting for cardiorespiratory fitness and other potential confounders… Muscular strength was independently associated with risk of death from all causes and cancer in men. These findings are valid for men of normal weight, those who are overweight, and younger or older men, and are valid even after adjusting for several potential confounders, including cardiorespiratory fitness.”

TL;DR: Increased muscular strength trumped all other indicators of health and was the single best predictor of reduced mortality in a 18.9 year study involving 8,762 test subjects and categorizing them into low, middle, and upper strength groups. The stronger people proved harder to kill and no inflection point was found.

Association between muscular strength and mortality in men: prospective cohort study

Associations of Muscle Mass and Strength with All-Cause Mortality among US Older Adults

Weightlifting is good for your heart and it doesn’t take much

Research indicates strength training may be more effective for heart health and overall health than cardio, especially for older people.

If we imagine some yet-to-be-found inflection point of negative health from increased strength does exist, the number of humans taking up barbell training that manage to reach that unicorn is too low to consider.