Background and Aim:Aging is associated with an increased risk of cardiometabolic diseases.Biological age is considered a useful indicator for evaluating healthy aging and maintaining quality of life.The present study aimed to investigate the effectiveness of 40 sessions of High-Intensity Functional Training(HIFT)on the modulation of biological age in women and men,and to compare sex-specific responses to this intervention.Materials and Methods:Data from 600 healthy men and women were used to train the model and extract the Klemera-Doubal(KDM)coefficients.100 healthy individuals with an average weight and age of 57 years and 80 kg were divided into two HIFT and control groups.40-session HIFT protocol was performed in accordance with the overload principle.Cardiometabolic indices were measured by standard laboratory methods, and biological age by the KDM method before and after a 40-session intervention.t-tests and Pearson correlation coefficient (at p≤0.05 level) were used to analyze the data.Results:Compared with the control group HIFT resulted in significant reductions in bodyweight(women p=0.03; men p=0.007)waist circumference(women and men p=0.001)and diastolic blood pressure(women p=0.002; men p=0.001)significant increases in total protein(women p=0.03; men p=0.02) and hemoglobin(women p=0.001;men p=0.01)in both sexes.Women exhibited significant reductions in body mass index (p=0.01),insulin(p=0.003)and triglycerides(p=0.001)along with significant increases in high-density lipoprotein cholesterol (p=0.001),urinary creatinine(p=0.01),and dominant handgrip strength(p=0.001).Men also showed significant reductions in body mass index(p=0.008),hematocrit(p=0.05)C-reactive protein(p=0.01)blood urea nitrogen(p=0.001),together with a significant increase in forced vital capacity(p=0.001). Compared to the control group, the HIFT intervention had a significant effect on reducing biological age(p=0.001)in women and men. Biological age in men and women in the HIFT group showed a significant decrease of 0.71 and 0.60 years, respectively (p=0.001). In the control group, a non-significant decrease of 0.06(p=0.3)and 0.04(p=0.7)years.Conclusion:HIFT with nutritional guidance improves biological age in both sexes by improving cardiometabolic biomarkers.The findings of this study highlight the importance of paying attention to regular physical activity in managing the aging process.