An optimal target of exercise therapy for the chronic stage of myocardial infarction (OMI) was proposed by investigating a daily total energy consumption (DTEC) in 172 outpatients (142 males and 30 females) with OMI. DTEC was significantly lower in OMI than in the preinfarction state: 2005.8 +/- 487.8 vs. 2451.6 +/- 631.7 Kcal (p less than 0.01) in the male, 1389.9 +/- 367.4 vs. 1626.2 +/- 426.0 Kcal (p less than 0.01) in the female. Limiting factors of a daily physical activity (DPA) in OMI were selected from various non-cardiac and cardiac factors by using multifactorial analysis (Hayashi III). Non-cardiac limiting factors included; age of greater than 60, house-wife, joblessness and female, sex, and cardiac limiting factors included; NYHA class II, III, low anaerobic threshold (AT), treadmill exercise tolerance of less than 6 min, Forrester subset III, IV, heart failure in OMI and the recurrence of MI. Eighty percent of patients without cardiac limiting factors restricted DPA by 25% of DTEC of the preinfarction state. Our optimal target of exercise therapy for OMI was set to resume DTEC up to the level before MI. For patients without exercise habits, activities requiring 100 to 150 Kcal a day were requested. Also, this regimen had an educational purpose to obtain self-confidence both mentally and physically and was expected to raise the level of DPA to that of preinfarction state.