The effect of an individual’s gender and height, and the perceptual characteristics of a bolus on sip volume
Background: This study placed focus on variables that may influence the amount of liquid an individual takes on an initial sip from a cup. There is ambiguity surrounding whether gender or height affects sip volume due to anatomical and structural differences that present between the sexes. There are also limited studies surrounding perceptual characteristics of a bolus and to what extent colour and taste affect sip volume. Research Aims: This current study aimed to determine the extent to which sip volume is affected by personal characteristics (e.g. height or gender of an individual). If there is a change in sip volume between the sexes when height categories are kept the same or different. Additionally, it aimed to investigate if sip volume is affected by internal characteristics such as taste or visual perception of the bolus. Method: 49 participants with typical swallows were recruited to fall within predetermined height categories: 160-165 cm, 170-175 cm or 180-185 cm. They were required to take a sip from nine different cups, as the study was repeated. Three of the cups contained unmodified still water, three contained unsweetened red water and the final three contained clear sweetened water. The cups were weighed before and after the participant took a sip to obtain an average sip volume result for each individual. Results: The findings from this study presented an average sip volume result of 20.36 ml. This highlighted no gender or height effect on sip volume, with no presenting difference between the three height categories. However, a weak positive correlation was present suggesting when height increased so did sip volume. It was also found that neither sweetness nor the colour red increased average sip volume. Discussion: Clinical considerations need to be made to modification of swallow assessments that do not yet incorporate larger bolus sizes. Alongside ways to elicit change in bolus size using perceptual characteristics.