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.

The effects of cranio-cervical flexion on activation of swallowing-related muscles.

We tested the effects of cranio-cervical flexion (CCF) on activation of swallowing-related muscles while swallowing liquid in a sample of 45 healthy volunteers. Activation following CCF movement was examined across two positions (supine and sitting) and, three pressure levels and two different postures were examined in each condition, respectively. When CCF was applied, activation of swallowing-related muscles was significantly increased compared to the neutral neck position, and such findings were found across both the supine and sitting positions. Also in the supine position, when the pressure level of the stabilizer was escalated, there was a significant difference in the activity of the swallowing-related muscles compared to the baseline level. In conclusion, our results suggest that CCF may be a viable method to enhance the effectiveness of swallowing-related muscles by changing neck position. When CCF is applied, the stability of the deep flexor muscles must be secured first after which superficially located muscles may better assist swallowing with less effort.

Exercise using tongue-holding swallow does not improve swallowing function in normal subjects.

We evaluated the effects of repetitive tongue-holding swallow (THS) as an exercise for improving swallowing function. Twenty healthy subjects were randomly divided into two groups. One group [THS group (THSG)] performed the tongue-holding manoeuvre every 5s for 20min. The other group (normal swallow group) swallowed without tongue-holding for the same length of time as a control. Twenty sessions of training were performed for 4weeks. All participants also had a videofluoroscopic swallowing study for analysing the biomechanical parameters of swallowing (hyolaryngeal movement, posterior pharyngeal wall movement and the pharyngeal constriction ratio). After 4weeks of training, none of the biomechanical parameters changed in either group. Exercise using THS did not affect swallowing function in normal subjects.