Changes of insulin-like growth factor I gene expression in gastrocnemius muscle of male Wistar rats after a period of high-intensity interval training

Studies have shown that insulin-like growth factor (IGF-I) is the main factor of growth and hypertrophy of muscle fibers. However, the effect of high-intensity interval training (HIIT) on IGF-I has not been well studied. The purpose of the present study was to investigate the changes of IGF-I gene expression in gastrocnemius muscle of male Wistar rats after a period of high-intensity interval training.
In this research study, 16 male Wistar rats (mean weight: 225±25 g) were randomly assigned into two groups: training (n=8) and control (n=8). After a week of familiarizing with training protocol, HIIT program was done 40 minutes each session, three sessions in a week for eight weeks. Then, 48 hours after the last training session, gastrocnemius muscle was extracted and the expression of IGF-I gene was determined by Real time-PCR technique. For statistical data analysis, independent t-test was used.
Statistical analysis showed that the value of gastrocnemius muscle IGF-I in the experimental group compared with the control group increased by more than 6 times (638%) (P=0.016). Gastrocnemius muscle weight was significantly increased in the exercise group compared with the control group (P=0.012).
HIIT exercise led to a marked increase in rats` IGF-I gene expression and gastrocnemius muscle weight.