息こらえ嚥下および強い息こらえ嚥下法での舌骨上筋・下筋群の筋活動量と筋疲労

Muscle activity and muscle fatigue of the suprahyoid and infrahyoid muscles during supraglottic swallowing and super-supraglottic swallowing

　摂食嚥下障害に対する訓練に，息こらえ嚥下と強い息こらえ嚥下法がある．この手技は嚥下中の誤嚥を防ぐ有効な訓練法である一方，対象者によっては筋疲労や飲み込みにくさを訴える場合もある．この要因の1つとして舌骨上筋・下筋群が過度な活動を起こしているのではないかとの仮説を立てた．本研究ではこの仮説を検証し，訓練をより安全に実施するための留意点を検討した．結果，筋活動量と飲み込みにくさは通常の嚥下より各嚥下法が，また息こらえ嚥下法より強い息こらえ嚥下法が有意に高く(すべてp＜0.001)，筋疲労は息こらえ嚥下法の咽頭期舌骨下筋群(p＝0.02)，強い息こらえ嚥下法の口腔期舌骨上筋・下筋群，咽頭期舌骨上筋群で有意に認められた(p＝0.003，p＝0.002，p＝0.02)．これらから，各嚥下法を実施する際は，筋活動や筋疲労に考慮した食事量の工夫，過度な筋活動を起こさせないように実施する方法の習熟が必要である．

　Dysphagia training includes exercising the supraglottic swallowing and super-supraglottic swallowing techniques. While these techniques are effective in preventing aspiration during swallowing, some subjects may complain of muscle fatigue and difficulty in swallowing. We hypothesized one of the reasons to be the excessive activity in the suprahyoid and infrahyoid muscles. Here, we tested this hypothesis and examined relevant points for providing a safer training. The results showed that muscle activity and swallowing difficulty were significantly higher for each of the swallowing techniques than for normal swallowing, and for super-supraglottic swallowing than for supraglottic swallowing (all p＜0.001). Muscle fatigue was significantly observed in the infrahyoid muscles during the pharyngeal phase of supraglottic swallowing (p=0.02). In super-supraglottic swallowing, muscle fatigue was observed in the suprahyoid and infrahyoid muscles during the oral phase and in the suprahyoid muscles during the pharyngeal phase (p=0.003, p=0.002, and p=0.02). Therefore, when using these swallowing methods, it is necessary to consider muscle activity and muscle fatigue for deciding the amount of food intake, and it is important to gain proficiency in order to avoid causing excessive muscle activity.