IOPI Northwest

After having carefully studied all of the published studies (in English) reporting tongue elevation strength in normal individuals, as determined by the IOPI or IOPI-like methods (See reference section), IOPI Northwest would offer the following guidelines:

• In a normal population, the average male Pmax is about 65 kPa, but in females, it is typically 4-5 kPa lower. Pmax in the healthy elderly is typically in the range of 55-40 kPa.
• In a normal population, there is considerable variability in tongue strength. There is no "defining value" for considering a person's tongue "weak." One can, however, estimate the probability of weakness. The probability is very high if Pmax is less than 30 kPa, even if the person is elderly.

 

• Patients with oral-phase swallowing problems have, on average, a lower Pmax than non-patients.

 

• Tongue exercise can increase Pmax in patients whose tongue is relatively weak to start with. At least 8 weeks of exercise is necessary to produce significant effects.

 

• Some evidence shows that increases in Pmax resulting from tongue exercise are associated with improved swallowing (see Robbins et al., 2007, Ref# 6). More research to document the efficacy of tongue exercise is needed, however.

 

• Use of tongue bulbs to measure the pressure generated by a normal swallow suggest a value of 20-30 kPa. Thus a substantial fraction of a person's tongue strength is used during swallowing.

Normal Values for lateral and protrusive tongue strength

Although there are very few publications that report objective measures of normal lateral and protrusive tongue strength (Clark et al., 2009, Ref #1), they suggest the following conclusions:

• Lateral tongue strength is about the same as the strength of tongue elevation.
• The strength of lateral tongue movements is very close to the same on the two sides.
• The strength of protrusive tongue movements is higher by about 10-20% than lateral or upward tongue movements.

Normal Values for tongue fatigue

On the basis of a 1992 study of about 200 normal individuals in and around Iowa City, Iowa, Professors Donald A Robin and Erich S. Luschei found that the average length of time that a person could hold 50% of their maximum tongue pressure was 35 seconds for males, with no apparent decline with increasing age. This length of time for females was about 35 seconds for young females, but dropped to about 30 seconds in the elderly (70-80 y.o.). Similar results on tongue endurance (the inverse of fatigue) have been reported by Youmans and Stierwalt, 2006, Ref# 7. See, however, their discussion of their results on this measure.