Immediately following a chest and shoulder workout a 55-year-old male executive complains of a "dull ache" in the left side of the chest that is aggravated by respiration. What would you consider is…

Cardiac pain is not characteristically worsened by respiration; it presents as pressure or tightness and may radiate to the arm or jaw independent of breathing.

Musculoskeletal pain is the most likely source because the onset followed resistance exercise targeting the chest and shoulder musculature, and the pain is worsened by respiration, which mechanically stresses the chest wall muscles, intercostal muscles, and costochondral junctions. Cardiac pain (angina) is typically described as pressure or squeezing, is not aggravated by the mechanical act of breathing, and is not directly linked to chest wall movement. This presentation is consistent with muscle strain or costochondritis provoked by the preceding workout.

A primary respiratory cause such as pleuritis is less likely here because the pain arose directly after resistance exercise targeting the chest and shoulder muscles rather than from a respiratory illness.

Delayed onset muscle soreness develops 24-72 hours after exercise and cannot explain pain that appears immediately post-workout.