Comparison of muscle activity between two adult groups according to the number of Shaker exercise

The purpose of this study was to investigate the muscle activity of the suprahyoid and infrahyoid muscles according to the number of Shaker exercise. The 19 experimental subjects were recruited and randomly assigned to the two experimental groups. The 1st experimental group performed Shaker exercise once a day, and 2nd experimental group performed Shaker exercise three times a day for 6 weeks. Shaker exercise consists of isometric and isotonic contraction movement, enhancing the strength of suprahyoid muscle and increasing the opening of UES. After performing Shaker exercise for 6 weeks, the muscle activity of experimental groups was measured and analysed by surface electromyography. As a result, muscle activity of the suprahyoid and infrahyoid muscles showed significant improvement in both groups (P < 0·05). Comparing muscle activity of both groups, there was no significant difference. This means the Shaker exercise shows similar exercise effects on suprahyoid muscle which is the primary target muscle irrespective of the number of Shaker exercise. The activity of the infrahyoid muscle, which takes a supportive role, also showed significant difference between the two groups. In the results of a follow-up test after 4 weeks, muscle activity was higher than the initial status and the value of the EMG activity was statistically significant (P < 0·05). These results by EMG study may suggest that Shaker exercise performed once a day, like performing three times a day, has enough exercise effect and there is similar effect on the suprahyoid muscle between the 2 groups. In addition, the exercise effect lasts for 4 weeks after completing exercise.