Biological age based on the assessment of various physiological factors measured in a resting state has been proposed as an appropriate index of aging. We have recently developed an equation for estimation of physical fitness age (PFA), which is composed of eight age-related physical fitness variables. These include oxygen uptake corresponding to lactate threshold (Vo₂@LT), maximal oxygen uptake (Vo₂max), side step, grip strength, vertical jump, foot balance with eyes closed, trunk extension, and trunk flexion. In this study, the validity of PFA as a critical index of physical health and/or aging status was investigated from a longitudinal standpoint on the assumption that exercise habituation does contribute to health promotion. The subjects were 14 Japanese middle-aged and elderly men, aged 50 to 70 years, all of whom were patients with coronary heart disease (CHD) . The subjects participated in a supervised exercise conditioning program for 90 to 120 min each session, 2 times weekly for 4 months. Analyses of the data indicated that the mean PFA of the subjects (66.0±9.0 yr) after conditioning was significantly (P<0.05) lower than the mean PFA (72.8±8.6 yr) obtained before conditioning. After the exercise program, significant increases were documented in Vo₂@LT (17%), Vo₂max (12%), side step (26%), trunk flexion (109%), trunk extension (7%), vertical jump (12%), and foot balance with eyes closed (31%) . Therefore, we conclude that our exercise conditioning program may alter the overall physical fitness of patients with CHD, and that PFA could be a valid physical health and/or aging index.