Relationship between Skeletal Muscle Health Index and Motor Function: Longitudinal Evaluation over 2 Years

Abstract

It is well known that muscle atrophy occurs as a result of aging. However, loss of muscle tissue also increases intramuscular adipose and connective tissues, which is known as deterioration of muscle quality. Ultrasound skeletal muscle images based on echo intensity （EI） are useful for assessing muscle quality. The purpose of this study was to investigate quality and quantity of skeletal muscle and physical performance of elderly individuals longitudinally. G60 and G70 groups consisted of 21 individuals with 65 or higher and 70 or lower and 27 individuals with 70 or higher and 82 or lower, respectively. EI, thicknesses of muscle and subcutaneous adipose tissue of the quadriceps, and 6 functional tests were performed at baseline and after 1 and 2 years. After two years follow-up, the EI of the vastus lateralis （VL） significantly increased in G60 and G70 groups, and muscle thickness of VL significantly decreased in G70. A significantly improvement was found in sit-up, sit-to-stand, and 5-m maximal walk tests in G60 and G70. These results suggested that age-related muscle atrophy over two years does not necessarily lead to functional impairment in older individuals.