Relationship between muscle stiffness and strength in older adults: implications for the development of sarcopenia (863.2)

Abstract

Introduction: It has been shown that older adults have an attenuated hypertrophic response to exercise as compared to young adults. One possible explanation for this response is decreased mechanotransduction into the myocytes due to stiffening of the extracellular matrix with the aging process; thus muscle cells will experience less strain and therefore less mechanical signaling for any applied force. We hypothesize that muscle stiffness decreases response to exercise, and that there is an inverse relationship between strength and muscle stiffness. This would indicate that muscle stiffening plays a role in the development of sarcopenia. Objective: The purpose of this study is to determine the relationship between muscle stiffness and strength in older adults. Methods: Data on muscle stiffness and strength were collected for 19 healthy women (age 70‐80). Stiffness measurements were taken of the Vastus Lateralis using ultrasound elastography (SuperSonic Imagine). Maximal strength was measured using a HUMAC isokinetic dynamometer. Results: Two subjects were excluded for lack of effort during strength testing. There was a moderate correlation (r=‐0.36) between strength and muscle stiffness. There was no relationship (r=‐0.2) between strength and age. Conclusions: This supports the hypothesis that muscle stiffness contributes to decreased response to exercise and the development of sarcopenia.