Tongue exercise and ageing effects on morphological and biochemical properties of the posterior digastric and temporalis muscles in a Fischer 344 Brown Norway rat model

suggest that: 1) Increasing age induces biochemical changes in muscles of the jaw, specifically showing an increase the proportion of slower contracting MyHC isoforms; 2) Increasing age and tongue exercise induce a reduction in muscle fiber cross sectional area in the temporalis muscle only. However, continued study of these cranial muscle systems is warranted to better understand these changes that occur with age and exercise.