The main topic of the research is to investigate the tongue's strength when swallowing. There has been much foreign literature on tongue strength. Iowa Oral Performance Instrument also has norms for reference, but the data are all taken from non-Asian people such as Caucasians. In this case, the credibility of the norms are decreased in domestic, and we also lack norm data of tongue strength when swallowing. Through the research, we can establish normative data belonging to the domestics, provide usable data for domestic researchers and clinical staff, and explore whether there are differences in age and gender in data between Taiwanese and foreigners.

Swallowing refers to the process by which food enters the stomach from the mouth. It is the physiological mechanism by which humans take in water and nutrients. It is a vital activity for individual survival. The physiological mechanism of swallowing has four major stages, oral preparation, oral cavity, pharynx, and esophagus. Each stage has its physiological mechanism, which depends on the different nerve and muscle structures. In the oral stage, our tongue plays an important role. Whether in the formation or transition of the food bolus, it must rely on the tongue to perform its normal functions. The main topic of the research is to explore the strength of the tongue when swallowing. The purpose is to discuss the influence of gender and age on swallowing tongue pressure. We expect to recruit 80 subjects and divide them into three groups according to their age: 20 to 39 years old, 40 to 59 years old, and 60 to 79 years old, with 13 to 14 males and females in each group, using Iowa Oral Performance Instrument measures the subject's maximum tongue pressure, average swallowing tongue pressure, and the ratio of the maximum tongue pressure used when swallowing, to explore whether age and gender affect tongue strength when swallowing.

Inclusion Criteria:

• Aged twenty and above.

Exclusion Criteria:

• Based on self-representation, has the disease of the nervous system, included stroke, brain trauma, Parkinson's disease, dementia, etc.
• Based on self-representation, has head and neck cancers.
• Based on self-representation, had any history of swallowing disorders.
• Based on self-representation, has obvious cognition impairment or language disorder that will affect measure procedure.

Based on gender identity.

Healthy adult.

Undecided.