Modified hybrid training and neuromuscular electrical stimulation increase quadriceps femoral and hamstrings muscle hypertrophy in untrained healthy subjects

Purpose: Low physical activity leads to muscle atrophy due to lack of exercise time and sport facilities. Addressing this issue, there are alternative methods with shorter training time and less equipment to induce muscle hypertrophy which are neuromuscular electrical stimulation (NMES) Russian protocol and modified hybrid training. We analyzed the difference in muscle hypertrophy of quadriceps and hamstrings between these two methodes in untrained healthy subjects. Methods: This study was an experimental study on 22 untrained healthy men aged 18-40 which were randomly assigned to the hybrid and NMES group. There were 11 people in each group undergoing the intervention three times a week for 4 weeks. At the beginning and end of the intervention, muscle thickness was measured by B-Mode ultrasonography. The results were compared between groups. Results: There was a significant increase in muscle hypertrophy in the hybrid group, which are quadriceps (dominant leg p=0.019, non-dominant leg p=0.007) and hamstrings (dominant leg p = 0.013, non-dominant leg p= 0,002). In the NMES group, a significant increase was found in the quadriceps muscle (dominant leg p=0.011, non-dominant leg p=0.002). There was a significant difference in the change of hamstring muscle thickness on the non-dominant leg (p=0.004) between the two groups. Conclusion: Modified hybrid training and NMES Russian protocol were shown to increase quadriceps and hamstring hypertrophy after 4 weeks intervention. In addition, modified hybrid training was shown to increase non-dominant side hamstring muscle hypertrophy greater than NMES Russian protocol.