Sir John Walsh Research Institute, University of Otago, Dunedin, New Zealand.
J Dent Res. 2011 Oct;90(10):1206-10. doi: 10.1177/0022034511416669. Epub 2011 Aug 1.
The aim of this observational study was to investigate the features of the chewing activity and the variability of the human chewing pace, as assessed in the natural environment. It was hypothesized that the chewing pace is relatively constant within individuals across different days but is variable across individuals. Electromyographic surface activity was recorded unilaterally from the masseter in 21 participants for 3 hours over 3 recording days, in the natural environment, by means of portable recorders. The time-frequency properties of chewing activity were assessed with a previously validated algorithm. Repeated-measurements ANOVA was used for statistical analysis. Chewing activity mainly occurred in the range of 0.94 Hz (5(th) percentile) and 2.17 Hz (95(th) percentile). Mean and median chewing frequencies were 1.57 Hz and 1.58 Hz, respectively (95% confidence intervals: 1.45-1.68 Hz). The mean duration of chewing episodes was 13.0 sec, the 5(th) and 95(th) percentiles being 2.7 sec and 34.9 sec, respectively. Variability of the mean chewing frequency between individuals was much greater than that within individuals (F = 29.8; p < 0.001). The individual chewing paces were stable across different days (intraclass correlation coefficient = 0.88; 95% confidence intervals = 0.79-0.94). Our findings provide evidence that each individual, in the natural environment, chews with a consistent pace across different days.
ANOVA, analysis of variance; CPG, central pattern generator; EMG, electromyography; ICC, Intra-class Correlation coefficient; SD, standard deviation.
本观察性研究旨在探讨咀嚼活动的特征以及人类咀嚼节奏的可变性，评估方法为在自然环境下进行。研究假设是个体在不同天数内的咀嚼节奏相对稳定，但在个体间存在差异。通过便携式记录器，在自然环境下，21 名参与者连续 3 天、每天 3 小时记录单侧咀嚼肌的肌电图表面活动。使用先前验证的算法评估咀嚼活动的时频特性。采用重复测量方差分析进行统计分析。咀嚼活动主要发生在 0.94 Hz（第 5 个百分位数）和 2.17 Hz（第 95 个百分位数）之间。平均和中位数咀嚼频率分别为 1.57 Hz 和 1.58 Hz（95%置信区间：1.45-1.68 Hz）。咀嚼事件的平均持续时间为 13.0 秒，第 5 个和第 95 个百分位数分别为 2.7 秒和 34.9 秒。个体间平均咀嚼频率的变异性明显大于个体内（F = 29.8；p < 0.001）。个体的咀嚼节奏在不同天数内是稳定的（组内相关系数 = 0.88；95%置信区间 = 0.79-0.94）。我们的研究结果表明，在自然环境中，每个个体在不同天数内以一致的节奏咀嚼。
ANOVA，方差分析；CPG，中枢模式发生器；EMG，肌电图；ICC，组内相关系数；SD，标准差。
