Age and Sex Effects on the Active Stiffness of Vastus Intermedius under Isometric Contraction

Abstract

Previously, a novel technique was proposed to quantify the relationship between the muscle stiffness and its nonfatigue contraction intensity. The method extended the measured range of isometric contraction to 100% maximum voluntary contraction (MVC) using an ultrasonic shear wave measurement setup. Yet, it has not been revealed how this relationship could be affected by factors like age or sex. To clarify these questions, vastus intermedius (VI) stiffness of 40 healthy subjects was assessed under 11 step levels of isometric contraction. The subjects were divided into four groups: young males, young females, elderly males, and elderly females (n = 10 for each). In a relaxed state, no significant difference was observed between the male and female subjects (p = 0.156) nor between the young and elderly subjects (p = 0.221). However, when performing isometric contraction, the VI stiffness of males was found to be significantly higher than that of females at the same level (p < 0.001), and that of the young was higher than the elderly (p < 0.001). Meanwhile, for two knee joint angles used, the stiffness measured at a 90° knee joint angle was always significantly larger than that measured at 60° (p < 0.001). Recognizing the active muscle stiffness of VI contributes to body stability, and these results may provide insight into the age and sex bias in musculoskeletal studies, such as those on fall risks.

Sonoelastography to Assess Muscular Stiffness Among Older Adults and its Use for the Diagnosis of Sarcopenia: A Systematic Review

“…Elastography was performed on different striated muscles both in the upper limb (i. e., biceps brachii [24] and supraspinatus [23]) and the lower limb (i. e., vastus lateralis [22], vastus intermedius [22,25,26], vastus medialis [22], rectus femoris [22,27,28], medial [20,28,29] and lateral gastrocnemius [20,27,29], soleus [27], and the hamstrings [22]). One study evaluated postural muscles: trapezius and erector spinae [30].…”

“…Wang et al constructed and used in their studies from 2014 and 2017 [25,26] a vibro-ultrasound system consisting of a mechanical vibrator, a programmable ultrasound scanner, and a custom-made program for radio-frequency data acquisition, based on the commercial ultrasound scanner SonixRP. Its measurement accuracy has been tested in the first study on a set of silicon phantoms of known shear moduli.…”

“…Wang et al 2017 [26] presented results that were already partially released in their 2014 study [25]. They tested the shear moduli of the vastus intermedius in all levels of mean voluntary contraction, starting with a relaxed state and ranging from 0°to 100°, increasing by 10°at each step and at two different knee joint angles (60°and 90°).…”

“…The applicability of certain studies was also put into question, because of the mean age of participants. Even though all studies included patients over 70 years old, the mean age of the elderly subgroup in some of them was too low (i. e., 56.7 ± 4.9 years in Wang et al 2014 [26] or 60.0 ± 6.1 years in Baumer et al, 2017 [23]).…”

Ultrasound Biomarkers for Sarcopenia: What Can We Tell So Far?

“…81 The decline correlated more strongly with muscle strength than muscle mass. Further research is needed to investigate if decreased muscle stiffness can predict adverse outcome in elderly individuals, but of note consensus is still lacking in the elastography literature as to whether muscle stiffness decreases, 82,83 increases, 84 or does not change 85 with aging.…”