Combined Aerobic and Resistance Exercise Program in Adults: Endocrine and Metabolic Adaptations

Background: Physical exercise induces coordinated endocrine and metabolic adaptations that contribute to the regulation of glucose homeostasis, lipid metabolism, stress responses, and anabolic processes. However, the integrated effects of combined aerobic and resistance exercise on multiple endocrine and metabolic outcomes require further investigation. This study aimed to evaluate the effects of a 12-week combined aerobic and resistance exercise program on endocrine and metabolic parameters in normal-weight and mildly overweight adults. Methods: A total of 60 adults were randomly allocated to an exercise group (EX, n = 30) or a control group (CON, n = 30). The EX-group completed a supervised 12-week combined exercise program consisting of three 60 min sessions per week, including aerobic exercise and multi-joint resistance training, whereas the CON-group maintained their habitual physical activity levels. Endocrine parameters, including insulin, glucagon, cortisol, growth hormone (GH), thyroid hormones, and sex-specific hormones, as well as fasting glucose, lipid profile, and homeostasis model assessment of insulin resistance (HOMA-IR), were assessed at baseline and after 12 weeks. Results: Compared with the control condition, the exercise program was associated with favorable changes in endocrine and metabolic profiles. The EX-group showed reductions in fasting insulin, cortisol, fasting glucose, and HOMA-IR, together with increased GH levels. Favorable changes were also observed in the lipid profile, including reductions in total cholesterol, low-density lipoprotein cholesterol (LDL), and triglycerides and an increase in high-density lipoproteins cholesterol (HDL). In the male subgroup, total testosterone increased following the intervention, whereas estradiol changes in the female subgroup were more limited. Changes in insulin were associated with changes in glucose regulation and lipid parameters, while GH and cortisol changes showed additional associations with metabolic outcomes. Conclusions: These findings support the role of structured combined exercise as a non-pharmacological strategy for promoting endocrine and metabolic health and preventing metabolic dysfunction.