Age-related difference of lip-closing force and/or handgrip strength

Objectives: The purpose of the present study was to quantitatively assess an age-related difference of the Lip-closing force (LCF) produced during maximum voluntary pursing-like lip movement and handgrip strength (HGS). Methods: The LCF and HGS were measured from three age groups; children (73 females, 95 males, mean age = 10.3 year old), healthy young adults (38 females, 55 males, 28.7) and healthy elderly adults (51 females, 38 males, 68.4). Total LCF in all directions (TLCF) was calculated by the sum of the LCF in all directions, measured by a multi-directional LCF measurement system. A grip dynamometer was used to measure the HGS. The correlation between the TLCF and the HGS was analyzed for each age group. The TLCF and the HGS were compared between the three age groups using repeated measures ANOVAs, with post hoc Tukey's multiple tests. Since there were gender differences for both the TLCF and the HGS, the age-related difference was assessed separately for each gender. P-values less than 0.05 were considered significant. Results: Significant correlation between the TLCF and HGS was found only in children. Both TLCF and HGS in children were lower than those in other two age groups. The TLCF in young adults did not differ from that in the elderly while the HGS in young adults was significantly higher than that in the elderly. The same age-related difference was noted for the two variables in both genders. Conclusions: Although there was an age-related difference for lip-closing force and the HGS, the changes of the neuromuscular function throughout a life time can differ between lip and hand muscles.