Task force II: Determination of occupational working capacity in patients with ischemic heart disease

Abstract

The physical, metabolic and cardiovascular demands of occupations in industrialized countries have substantially declined during the past century. Many jobs that once required substantial physical effort are now performed by machines, robots or computers. This decrease in job-related energy demand is especially apparent in occupations performed by people over age 40, who, given some seniority, rarely perform physical tasks exceeding a peak energy expenditure of 5 kcaVmin or 3.5 METS, where 1 MET = energy expenditure sitting at rest (I). Nonetheless, the physical stress of employment is still the greatest challenge to the cardiovascular system of many patients with ischemic heart disease. For many sedentary jobs posing limited psychological or environmental demands, the adequacy of the patient’s physical working capacity can be assessed by a medical history, physical examination and symptom-limited exercise testing. However, as the physical demands of the job tasks increase to include exercise of widely varying intensities and types, or substantial psychological or environmental stress, assessment of physical working capacity becomes more complex. In patients with ischemic heart disease, the focus of occupational work evaluation is to determine whether or not the increase in cardiac demands produced by physical, psychological and environmental stressors will exceed the threshold for a “safe working capacity.” The challenge to the physician is to obtain an accurate, valid and reliable determination of this capacity.