Objectives: To give a description of normal surface electromyography (sEMG) aspects of uninterrupted (continuous) drinking and to establish normal sEMG values for swallowing 100 mL of water.
Study design: Prospective observational study of healthy volunteers.
Subjects: Four hundred twenty apparently healthy male and female volunteers divided into three age groups (18-40, 41-65, 66+ years).
Methods: The evaluated parameters included the total duration, number of swallows, amount of water per swallow, and voltage of the EMG activity of the orbicularis oris, masseter, and submental-submandibular muscles and the infrahyoid muscle groups covered by the m. platysma.
Results: The overall normal mean values for duration, number of swallows, and amplitude of muscle activity during continuous drinking were compiled. The age-related increase in duration of swallows and of total drinking time was significant only in the older group (95% confidence interval, P < .05). There were no significant sex-related differences for any age group (P > or = .05). The mean electric activity (in muV) varied insignificantly among the age groups. The activity of the m. orbicularis oris was the least informative. An unexpectedly significant number of healthy subjects (14.25%, P < .05) performed a dry swallow after drinking.
Conclusion: The establishment of normal sEMG levels now makes this modality applicable for evaluating the swallowing mechanism among adults for potentially identifying and ruling out abnormalities. Its simplicity, noninvasiveness, and low level of discomfort also make it highly suitable for screening purposes.