Dynamic shear wave elastography for the flexor digitorum superficialis: The correlation with physical performance in hospitalized older adults

Shear wave elastography (SWE) can quantify muscle stiffness to reflect the muscle quality, and we explored the application of SWE in assessing physical performance. In this work, a total of 98 older adults, including 55 men and 43 women, were recruited in this cross-sectional study. Short physical performance battery (SPPB) and time-up-and-go (TUG) test were used to evaluate physical performance, and a dynamic SWE imaging for the flexor digitorum superficialis in the process of using grip strength meter was documented. The peak strength and peak shear wave velocities (SWV) were recorded, and the ratio of peak SWV to peak strength was defined as the standardized muscle contractive stiffness. For men, the peak SWV was negatively correlated to SPPB scores (r = -0.351 to -0.448, all P < 0.01) and positively correlated to TUG time (r = 0.299-0.369, all P < 0.05), and the standardized muscle contractive stiffness was significantly negatively correlated to SPPB scores (r = -0.501 to -0.532, all P < 0.01) and positively correlated to TUG time (r = 0.424-0.462, all P < 0.01). For women, the peak SWV was not correlated to physical performance, and the standardized muscle contractive stiffness was correlated to the TUG time (r = 0.312 for Cmax and 0.310 for Cmean, both P < 0.05). Those participants with decreased physical performance had significant higher standardized muscle contractive stiffness in both men and women (all P < 0.05). We proved that SWE can be applied in evaluating muscle function and the flexor digitorum superficialis contractive stiffness standardized by grip strength can be a potential indicator.