Relationship Between Muscle Quality or Stiffness Measured by Ultrasonography and Range of Motion in Hospitalized Older Adults

Muscle and tendon stiffness of lower extremity in older adults with fall history: Stiffness effect on physical performance and fall risk

Changes in muscle and tendon stiffness may lead to falls in older adults by affecting joint stability and muscle function. This study aims to investigate the changes in stiffness in lower extremity muscles and tendons in the older adults with a fall history. A cross-sectional research design was followed. 25 older adults with a fall history and 26 older adults without fall history were recruited study. Stiffness of the lower extremity muscles and tendons was measured using a MyotonPRO device. Balance and functional ability of the participants were evaluated. The stiffness of all the selected muscles and tendon was lower in the older adults with a history of fall compared to controls (p<0.05). The obtained results suggest the decrease in the stiffness of the lower extremity muscles and tendon may negatively affect muscle function and joint stability/ control, and it may increase the predisposition to falling in older adults.

Contribution of muscle stiffness of the triceps surae to passive ankle joint stiffness in young and older adults

This study aimed to investigate whether triceps surae muscle stiffness is associated with passive ankle joint stiffness in 40 young (21-24 years) and older (62-83 years) males. Using ultrasound shear wave elastography, the shear modulus of each muscle of the triceps surae (the medial [MG], lateral gastrocnemius [LG], and soleus [Sol]) was assessed as muscle stiffness at the ankle neutral position (NP) and 15-degree dorsiflexed position (DF15) with the knee fully extended. Passive ankle joint stiffness at the NP and DF15 was calculated as the gradient of the angle-torque relationship at each joint angle during passive ankle dorsiflexion at 1°∙s^-1 controlled by using an isokinetic dynamometer. Passive ankle joint stiffness was normalized by the body mass. There was no correlation between the absolute ankle joint stiffness and muscle shear modulus of triceps surae in the young and older groups at the NP (r ≤ 0.349, p ≥ 0.138). Significant positive correlations between absolute ankle joint stiffness and muscle shear modulus at DF15 were observed for MG and Sol in the young group (r ≥ 0.451, p ≤ 0.044) but not in the older group. The normalized ankle joint stiffness at the NP was significantly positively correlated with the LG shear modulus in young participants and with the MG and LG shear modulus in older participants (r ≥ 0.466 and p ≤ 0.039). There were significant positive correlations between the normalized ankle joint stiffness and the muscle shear modulus of the triceps surae at DF15 in young and older participants (r ≥ 0.464 and p ≤ 0.040), except for the MG shear modulus in older participants (r = 0.419 and p = 0.066). These results suggest that the material properties of the entire triceps surae, even Sol, which is the most compliant muscle among the triceps surae, affect passive ankle joint stiffness, especially when the triceps surae is lengthened and body size is considered.