Effects of an Eight-week High-intensity Interval Training Program on Body Composition, Cardiopulmonary Function, and Cardiopulmonary Fitness in Sedentary Women in Their 30s and 40s

OBJECTIVES This study analyzes the effects of high-intensity interval training on body composition, resting heart rate, blood pressure, waist-to-hip ratio, and cardiopulmonary fitness in sedentary women in their 30s and 40s. METHODS Participants included sedentary women in their 30s and 40s living in S City, the Republic of Korea. They were divided into high-intensity interval training (n=10) and control groups (n=11). The training program period was eight weeks from January to February 2025. The high-intensity interval training group walked on a treadmill for 2 to 3 minutes at 40-50% of the target heart rate, then ran for 40 seconds to 1 minute at 80% or higher of the target heart rate, and finally walked at a low speed of 40-50% of the target heart rate for 1 minute. Depending on their condition, they performed a minimum of 6 and maximum of 10 sets. The control group did not participate in any physical activity or exercise program other than daily life during the eight-week period. A 2×2 repeated analysis of variance was performed to analyze the differences between the control and exercise groups according to the timing of the eight-week exercise. The interaction effect of program participation was examined by examining the change in time before and after the group. The statistical significance level was set at p<0.05. RESULTS No significant differences were observed between the groups in weight, body mass index, total body water, skeletal muscle mass, body fat, percent body fat, systolic blood pressure, diastolic blood pressure, and hip circumference before and after exercise (p>0.05). Meanwhile, resting heart rate (F=25.459, p<0.001), waist circumference (F=9.356, p=0.006), waist-to-hip ratio (F=21.294, p<0.001), Cooper 12-Minute Run Test (F=26.086, p<0.001), and Queen’s College Step Test (F=9.767, p=0.006) showed significant differences. CONCLUSIONS Eight weeks of high-intensity interval training did not show any significant changes in body composition and blood pressure in sedentary women in their 30s and 40s. However, it improved the resting heart rate, waist circumference, waist-to-hip ratio, and cardiopulmonary fitness.