This study investigates the relationship between physical activity in occupation and the incidence and severity of coronary heart disease in middle-aged British men. The researchers analyzed 5,000 necropsy reports from 206 hospitals, focusing on the frequency of ischemic myocardial fibrosis, a sign of early coronary heart disease. They classified occupations into three groups based on physical activity: light (e.g., bus drivers, clerks), active (e.g., postmen, carpenters), and heavy (e.g., boilermakers, dock laborers). The results showed that men in light occupations had a significantly higher prevalence of ischemic myocardial fibrosis compared to those in heavy occupations, with a stronger gradient for large fibrous patches. This trend was consistent across different age groups and regions. The study also found that hypertension was associated with a higher prevalence of small, multiple scars, particularly in light workers. Additionally, the prevalence of severe coronary atherosclerosis was higher in hypertensive cases, but there was no significant occupational difference in the frequency of lesser degrees of coronary narrowing. The findings suggest that physical activity in occupation may protect against coronary heart disease, with physically active and heavy workers having lower rates of the disease. The study concludes that physical activity in work may be a protective factor against coronary heart disease, and further research is needed to explore the mechanisms behind this relationship.This study investigates the relationship between physical activity in occupation and the incidence and severity of coronary heart disease in middle-aged British men. The researchers analyzed 5,000 necropsy reports from 206 hospitals, focusing on the frequency of ischemic myocardial fibrosis, a sign of early coronary heart disease. They classified occupations into three groups based on physical activity: light (e.g., bus drivers, clerks), active (e.g., postmen, carpenters), and heavy (e.g., boilermakers, dock laborers). The results showed that men in light occupations had a significantly higher prevalence of ischemic myocardial fibrosis compared to those in heavy occupations, with a stronger gradient for large fibrous patches. This trend was consistent across different age groups and regions. The study also found that hypertension was associated with a higher prevalence of small, multiple scars, particularly in light workers. Additionally, the prevalence of severe coronary atherosclerosis was higher in hypertensive cases, but there was no significant occupational difference in the frequency of lesser degrees of coronary narrowing. The findings suggest that physical activity in occupation may protect against coronary heart disease, with physically active and heavy workers having lower rates of the disease. The study concludes that physical activity in work may be a protective factor against coronary heart disease, and further research is needed to explore the mechanisms behind this relationship.