What muscle expansion would restrict blood flow to heart?

Muscle expansion that could restrict blood flow to the heart typically occurs when the surrounding skeletal muscles, particularly those in the thoracic region, contract excessively during intense physical activity. This contraction can compress the thoracic cavity and impede venous return to the heart. Additionally, conditions like hypertrophic cardiomyopathy, where the heart muscle thickens, can also obstruct blood flow and lead to restricted blood flow to the heart itself. Both scenariOS can result in reduced cardiac output and potential cardiovascular complications.