Responses of Plasma Levels of Irisin, Follistatin and Insulin Resistance Index to Two Types of High Intensity Interval Training in Overweight Men

Irisin is an exercise-stimulated hormone that affects white adipose tissue and brown adipose tissue. Based on the previous studies, physical activity increases the expression of proteins such as follistatin, which causes weight loss by increasing energy expenditure and through this has an effect on the insulin resistance index. The present study aimed to investigate the response of plasma levels of irisin, follistatin, and insulin resistance index to two types of high-intensity interval training (HIIT) in overweight men.

 For this purpose, 33 overweight men (mean age 22.9±2.11 years, weight 82.45±6.1 kg, body mass index 26.7±1.22 kg/m²) who were able to regularly attend physical activity voluntarily participated in the study and were randomly divided into three groups: 30-s HIIT groups (HIIT-30), 60-s HIIT (HIIT-60), and control. The training protocol was performed three sessions per week for eight weeks. The HIIT-30 exercise program included eight repetitions of 30-second activity at an intensity of 80-90% of the maximum heart rate with a two-minute recovery for the first four weeks, ten repetitions for the fifth and sixth weeks, and twelve repetitions for the seventh and eighth weeks. The HIIT-60 exercise program included four repetitions of 60-second activity at an intensity of 80-90% of the maximum heart rate with a four-minute recovery for the first four weeks, five repetitions for the fifth and sixth weeks, and six repetitions for the seventh and eighth weeks. The control group did not attend any regular exercise program during the research. Blood samples were taken to measure levels of Irisin, follistatin, and determine the insulin resistance index. One-way analysis of variance (ANOVA) and paired t-test were utilized at a level of P≤0.05 to compare means of parameters.

 The within-group comparisons for irisin and follistatin data showed that there is a significant difference between pre-test and post-test in the 30-s HIIT and 60-s HIIT groups (P<0.05). The results of ANOVA indicated that the 30-s HIIT and 60-s HIIT protocols increased the levels of irisin (P<0.05), follistatin (P<0.05), and reduced insulin resistance index significantly (P<0.05). The between-group comparisons of the data showed no significant differences between the HIIT-30 group and the HIIT-60 group for all variables.

 According to the results of this research, it could be concluded that, the two HIIT methods of 30 and 60 seconds by increasing irisin and follistatin levels can cause weight loss, treat obesity and improve the insulin resistance index in overweight men.