[Surface electromyographic study on swallowing in normal adults]

To study the characteristics of surface electromyography (sEMG) during swallowing in normal adults.

The sEMG during swallowing was carried out in 126 normal adults. There were 66 males and 60 females with their age ranged from 18 to 65 years. The recording electrodes were placed on the skin above the superior thyroid notch and the duration and amplitude of muscle activities during every deglutition were recorded. Swallowing styles were dry swallow, 20 ml water swallow and 40 ml water swallow.

The durations of sEMG at dry swallow, 20 ml water swallow and 40 ml water swallow were (1.133 ± 0.209)s (x¯ ± s), (1.097 ± 0.208)s, and (1.510 ± 0.432)s, while the amplitudes were (0.332 ± 0.115)mV, (0.308 ± 0.095)mV, and (0.399 ± 0.139)mV in normal male group. The durations of sEMG at dry swallow, 20 ml water swallow and 40 ml water swallow were (1.118 ± 0.170)s, (1.085 ± 0.209)s, and (1.765 ± 0.463)s, while the amplitudes were (0.292 ± 0.100)mV, (0.261 ± 0.113)mV, and (0.342 ± 0.129)mV in normal female group. The amplitudes of sEMG in male were higher than those in female (P < 0.05) and the durations had no statistically significant difference between male and female (P > 0.05) in all swallow styles except that the duration of 40 ml water swallow in female was longer than that in male (P < 0.05). In all volunteers, the durations of sEMG at 40 ml water swallow were longer than those at dry swallow and 20 ml water swallow, and there was no statistically significant difference between dry swallow and 20 ml water swallow. The amplitude of sEMG at 40 ml water swallow was higher than that at dry swallow. The amplitude of sEMG in dry swallow was higher than that at 20 ml water swallow. There was no statistically significant difference in durations and amplitudes of sEMG among four different age groups of male. In the female groups, there was no statistically significant difference in durations and amplitudes of sEMG among four different age groups except that the duration at 40 ml water swallow was longer in younger group (<30 years old) than in older groups.

Surface EMG of swallowing is a simple and noninvasive method for evaluating the swallowing function. The sEMG data of swallowing in normal adults obtained in this study may be used to provide reference for screening swallowing function in adults in the future.