The effect of twelve weeks of aerobic interval training on liver complications and cardiovascular risk factors in men with type 2 diabetes

Background & Aims: One of the main complications of type 2 diabetes is cardiovascular complications, which greatly increases mortality and reduces the quality of life of these patients. Complications of type 2 diabetes, which are known as cardiovascular risk factors, include dyslipidemia (1, 3) and high blood pressure, which are common diseases in type 2 diabetes (1, 4). Another complication of type 2 diabetes is liver complications (5). Which is associated with cardiovascular risk factors (5, 8) in type 2 diabetes. Despite extensive research to identify the pathological causes of type 2 diabetes, no definitive treatment for type 2 diabetes has been found so far, and the annual death rate from type 2 diabetes and liver disorders due to diabetes due to cardiovascular events is increasing (5). Indicating the need for further research to reduce cardiovascular risk factors in these patients. Exercise is one of the main pillars in the treatment of type 2 diabetes (13), but these patients may be limited in performing continuous aerobic exercise due to overweight and low level of physical fitness (14); For this reason, interval training is recommended for these patients because resting between exercise intervals reduces the cardiac stress caused, leading to metabolic recovery and rebuilding energy systems, allowing for more exercise in one session (18); Therefore, the aim of this study was to investigate the effect of interval aerobic training on cardiovascular risk factors including cardiovascular and hepatic complications in men with type 2 diabetes.   Methods:  In the present quasi-experimental study, 20 men with type 2 diabetes were randomly selected from volunteer patients aged 35 to 50 years, sedentary lifestyle (no physical activity in the last six months), no insulin injection, no acute cardiovascular disease, no respiratory disease, and no musculoskeletal disease. Then, they were randomly divided into two groups of aerobic interval training and control. Exercise training intervention in the present study included 12 weeks of aerobic interval training, three sessions per week and each exercise session included 1)10-15 minutes of warm-up, 2) the main exercise program (10-40 minutes aerobic interval training with 5 minute intervals and a rest-to-activity ratio of 1: 1), 3) and 10 minutes of coolingdown. 24 hours before the intervention and 48 hours after the last training session, the research variables were measured in fasting. Paired sample t-test and independent t-tests were used to examine changes within and between groups. All statistical analysis operations were performed at the significant level of P 05 0.05 by SPSS software version 22. Results: The results showed that after the training period there was founded a significant decrease in the levels of HbA1c (P <0.001), triglyceride (P = 0.038), low-density lipoprotein (P = 0.008), alanine aminotransferase (P <0.001), aspartate aminotransferase (P <0.001), systolic blood pressure (P = 0.06) and body fat percentage (P = 0.003) and significant increase in high-density lipoprotein (P = 0.002) And maximum oxygen consumption (P <0.001) was observed compared to the control group, but there was no a significant difference in changes in total cholesterol (P = 0.159), diastolic blood pressure (P = 0.211) and body weight (0.061). = P) between training and control groups. Conclusion: Regarding the chronic effect of regular exercise on glycemic control in diabetic patients, it can be said that aerobic interval exercise has increased glycemic control in patients with type 2 diabetes by increasing cell sensitivity with insulin-dependent molecular pathways and insulin-independent pathways (19). Also, after the training period, was observed a significant decrease in body fat percentage. The ratio of fat to muscle mass plays an important role in insulin resistance and metabolic disorders (21); therefore, the decrease in HbA1c caused by exercise can be justified in relation to the reduction of body fat percentage. Also, after the training period, a significant improvement in lipid profile was observed in the form of a decrease in triglycerides and LDL and a significant increase in HDL levels. The improvement in lipid profile in the present study may be due to the reduction of insulin resistance and glycemic control in adaptation to periodic aerobic exercise (16). Also, a significant decrease in serum aminotransferases was observed in the exercise group compared to the control group; it can be said that improving insulin resistance in the liver has reduced the accumulation of triglycerides in hepatocytes, which has resulted in reduced hepatic steatosis and improved liver function in patients. It is reported that body composition and HbA1c levels were associated with NAFLD. Also, after the training period, a significant increase in VO2max was observed compared to the control group. Cardiorespiratory fitness, measured by maximal oxygen consumption (VO2max), is related to functional capacity and human function and has been shown to be a strong predictor of disease mortality (27). One of the complications of diabetes is decreased functional ability in patients during exercise, the optimal delivery and use of oxygen means the interaction of various physiological functions, such as pulmonary ventilation, gas exchange, cardiac output, muscle blood distribution, aerobic capacity and energy production in skeletal muscle, as well as perception of fatigue (14). It can be said that exercise improves the function of the cardiorespiratory system by increasing the absorption and delivery of oxygen to the active muscles. Also in the present study, a significant decrease in systolic blood pressure was observed compared to the control group. Due to the fact that exercise training can affect vascular function and thus the response to vascular flow, it can increase blood flow to active muscles during exercise and provide the need for muscle oxygen by increasing blood flow, as well as increasing flow. The blood expels the metabolites produced and thus reduces the accumulation of these metabolites in the muscles (4, 28). On the other hand, by reducing insulin resistance in muscle cells, glucose uptake increases and as a result, glycogen stores in muscle cells increase, which can be useful in performing long-term exercise. Improving insulin signaling also leads to better glucose uptake during exercise (27, 29), resulting in better performance in long-term aerobic activity.