Abstract
BACKGROUND AND AIMS: This study set out to examine the stiffness of the gastrocnemius medialis (GM) and Achilles tendon across postmenopausal women with osteosarcopenia (OS), osteoporosis (OP), and normal bone mineral density. Furthermore, we explored the relationship between muscle-tendon stiffness and postural sway during a curve-tracking task in both sagittal (AP) and frontal (ML) planes. METHODS: Seventy-three women volunteered to participate in this study. The participants were classified into OS (T-score ≤ - 2.5 and muscle mass below 5.5 kg/m(2)), OP (T-score ≤ - 2.5), and healthy (T-score >-1) groups. The shear wave elastography was used to determine GM and Achilles tendon stiffness during rest and activation. The postural sway was recorded using a force plate during the performance-based curve tracking (CT) task. RESULTS: The stiffness of the GM and Achilles tendon was found to be significantly lower in the OS group compared to the OP and healthy groups (P < 0.05). In the CT task, the OS group exhibited a significant decrease in the mean absolute (P = 0.011) and RMS error (P = 0.022) in the ML direction compared to the OP group. Additionally, a positive correlation was found between the ML mean absolute error and both GM and Achilles's stiffness during rest and activation (P < 0.05). DISCUSSION AND CONCLUSION: The OS group exhibited the lowest muscle-tendon stiffness. The GM and Achilles stiffness was positively correlated with poor performance-based balance, particularly in the ML direction. This may increase the risk of falls and subsequent hip fractures during simple daily weight- shifting activities in women with osteosarcopenia.