Iizumi T, Magara J, Tsujimura T, Inoue M
Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
Department of Communication Disorders, School of Rehabilitation Sciences, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido, Japan.
J Oral Rehabil. 2017 Nov;44(11):835-842. doi: 10.1111/joor.12555. Epub 2017 Sep 10.
Mastication is essential to the eating process and forms an important part of feeding behaviour. Many factors related to the food bolus, such as bolus texture and size, are known to influence mastication. The aim of this study was to determine the effects of body posture on (i) chewing duration prior to the first swallow and (ii) patterns of mastication-related EMG activity. We asked 10 healthy adults to chew 8 g of steamed rice with barium sulphate while we recorded masseter, suprahyoid and infrahyoid muscle activity and simultaneously collected videofluorographic images. Participants chewed in either an upright or reclining position. Chewing duration, which was defined as the time from the start of mastication to the first swallow, was not different between the positions. However, the variability of chewing duration was larger in the upright versus reclining position, and the chewing duration in the reclining position was distributed around 15 s. Masseter activity gradually decreased in a time-dependent manner and was significantly larger at the early versus late stage of mastication. Suprahyoid activity was significantly larger at the early versus middle stage of mastication in the upright position only. Finally, masseter activity per second was negatively correlated with changes in chewing duration, that is, the larger the increase in chewing duration in the reclining position, the more the decrease in masseter activity per second. These results suggest that position-dependent changes in chewing behaviours, as described by chewing duration and EMG activity, may vary among participants.
咀嚼对于进食过程至关重要，是进食行为的重要组成部分。已知许多与食团相关的因素，如食团质地和大小，都会影响咀嚼。本研究的目的是确定身体姿势对（i）首次吞咽前的咀嚼持续时间和（ii）咀嚼相关肌电图活动模式的影响。我们让10名健康成年人咀嚼8克掺有硫酸钡的蒸米饭，同时记录咬肌、舌骨上肌和舌骨下肌的活动，并同步收集视频荧光图像。参与者分别在直立或躺卧姿势下咀嚼。咀嚼持续时间定义为从开始咀嚼到首次吞咽的时间，两种姿势下的咀嚼持续时间没有差异。然而，直立姿势下咀嚼持续时间的变异性大于躺卧姿势，躺卧姿势下的咀嚼持续时间分布在15秒左右。咬肌活动随时间逐渐降低，咀嚼早期的咬肌活动明显大于晚期。仅在直立姿势下，舌骨上肌活动在咀嚼早期大于中期。最后，每秒咬肌活动与咀嚼持续时间的变化呈负相关，即躺卧姿势下咀嚼持续时间增加越多，每秒咬肌活动减少越多。这些结果表明，咀嚼持续时间和肌电图活动所描述的咀嚼行为的姿势依赖性变化可能因参与者而异。
