Effects of prolonged whey protein supplementation and resistance training on the gene expression of IGF-1 and gastrocnemius muscle weight in young male Wistar rats

This study aimed to investigate the combined effect of prolonged whey protein supplementation and resistance training on the expression of the insulin-like growth factor-1 (IGF-1) gene, the weight of the Gastrocnemius muscle, and One-repetition maximum in young male Wistar rats. In this study, twenty-one young male Wistar rats, aged eight weeks and weighing between 200 to 250 grams, were randomly assigned to four groups: training (T), supplementary training (ST), Sham (Sh), and control (C). The resistance training program was conducted for six weeks, five days a week, with the training intensity increasing from 50 to 100% of the rats body weight. The rats received the whey supplement via the gavage method based on their body weight, using whey production by ON company. Forty-eight hours after the final training session, the quadriceps muscles of the rats were extracted and the expression level of the IGF-1 gene was evaluated using the Real-Time PCR method. Statistical analysis was conducted using a one-way variance test and Scheffe s test. The results showed that the training-supplement group exhibited a significant increase in IGF-1 expression compared to the sham group (P˂0.05). Moreover, the weight of the gastrocnemius muscle of rats and also the One-repetition maximum in the training-supplement group significantly increased compared to the training, sham, and control groups (P˂0.05). The findings suggest that the concomitant use of resistance training and whey protein supplementation has a synergistic effect on IGF-1 gene expression in skeletal muscle, which may contribute to enhanced muscle hypertrophy and 1RM.