M.M. COWAN and L.W. GREGORY. Responses of pre- and post-menopausal females to aerobic conditioning.Med. Sci. Sports Exerc. Vol. 17, No. 1, pp. 138–143, 1985. This study sought to determine whether the ability to improve cardiorespiratory endurance and body composition is affected by the menopausal status of females. Twenty premenopausal females and 18 postmenopausal females, ages 35–49 and 47–66 yr, respectively, were randomly assigned to exercise and control groups depending on menopausal status. Both exercise groups (PRE-EX,N= 16; POST-EX,N= 14) participated in a progressive walking program (4 days/week for 9 weeks) at an intensity of 80% the age-adjusted heart rate maximum (80% HRM). Following training, both exercise groups significantly improved submaximal exercise capacity (SEC) as measured by oxygen consumption (l/min; ml/kg-min) and treadmill walking time at 80% HRM. The PRE-EX group significantly improved percent body fat and lean body weight, while there was no significant change in total body weight. The POST-EX group significantly improved total body weight and percent body fat with no significant change in lean body weight. Although some of these changes in body composition were statistically significant, overall the alterations were minimal. ANCOVA revealed exercise, not menopause, to be the effective treatment for improving percent body fat and SEC80%HRM. There were no significant differences between the PRE-EX and POST-EX groups in their ability to improve SEC80%HRMor to reduce percent body fat. The POST-EX group had a significantly greater reduction in total body weight, while the PRE-EX group had significantly greater increases in lean body weight. These findings suggest that the ability to favorably alter body composition and cardiorespiratory endurance through the aerobic conditioning of females is independent of menopausal status.