The aim of this study was to compare circulatory responses to circuit weight (CWT) and aerobic walking training sessions of similar energy cost in middle-aged overweight females. Thirty-three middle-aged pre-menopausal females participated in the experiment. They were divided into overweight (n=18, 36.2 +/- 6.3 years, 166.3 +/- 8.0 cm, 83.5 +/- 9.7 kg, BMI 30.2 +/- 3.1 kg m-2) and non-overweight control (n=15, 34.1 +/- 6.3 years, 165.0 +/- 5.6 cm, 61.6 +/- 5.0 kg, BMI 22.7 +/- 1.5 kg m-2) groups. Individual physical working capacity (PWC) was measured using the cycle ergometer test (calculated at the level of predicted HRmax (205 - (1/2) age). A CWT session consisted of leg extension, bench press, sit-ups and leg press exercises. The subjects performed four circuits at the maximal possible speed, using a work-to-rest ratio of 60 s. Blood pressure (BP) was measured during every rest period between the exercises, and the heart rate (HR) was recorded continuously during the whole CWT programme. During the walking training session, the subjects walked as fast as possible on the indoor track. The total energy cost of the walking training session was the same as during the CWT session, approximately 270 kcal, and was controlled by a CALTRAC accelerometer. HR and BP were measured every 5 min during the walking training session. The PWC index was significantly (P<0.05) higher in the overweight group in comparison with the control females (215.4 +/- 76.1 and 187.9 +/- 42.4 W, respectively). The resting BP was normal in both groups (<140/90 mmHg). HR was between 120 and 140 beats min-1 during CWT and walking sessions. There were no differences in BP during both training sessions in overweight and control subjects. It was concluded that both CWT and walking training sessions were acceptable forms of physical activity to increase cardiovascular fitness in middle-aged overweight and normal body weight females.