INTRODUCTION: It is well known that degenerative changes associated with aging occur in skeletal muscles. However, there are only a few studies that have focused on age‐related changes in abdominal muscles. We investigated the age‐related changes in the muscle thickness of the deep and superficial abdominal muscles.
METHODS: The subjects comprised 100 women who could walk unassisted or with a walking aid. All subjects were informed about our study and provided a written informed consent. They were classified into 5 groups: young (26 subjects; 20 to 24 years), young adult (24; 25 to 44), middle‐aged (16; 45 to 64), young‐old (16; 65 to 74), and old‐old (18; 75 to 85). Muscle thicknesses of the right rectus abdominis (RA), external oblique (EO), internal oblique (10), and transversus abdominis (TrA) were measured using ultrasonography. Differences in muscle thickness between the groups were examined using ANOVA and post‐hoc test. Significance was recognized at p< 0.05.
RESULTS: The RA thickness in the middle‐aged (8.2 mm), young‐old (7.8 mm), and old‐old (7.0 mm) groups were significantly thinner than that in the young group (11.3 mm). Similarly, the EO thickness in the middle‐aged (5.9 mm), young‐old (4.4 mm), and old‐old (4.1 mm) groups were significantly thinner than that in the young group (7.7 mm). The 10 thickness in the middle‐aged (8.2 mm), young‐old (7.1 mm) and oldold (5.8 mm) groups were significantly thinner than that in the young group (11.0 mm). On the other hand, as for the TrA thickness, a significant difference was found between only the young (4.4 mm) and old‐old (3.4 mm) groups.
DISCUSSION: The RA, EO and 10 were decreased after middle‐aged. However, only the TrA was maintained until becoming elderly. Our results suggest that the TrA among abdominal muscles is the least affected by aging.