Ultrasound Measurements of Skeletal Muscle Architecture Are Associated with Strength and Functional Capacity in Older Adults

The goal of this study was to determine whether ultrasound measures of muscle architecture can be used to infer strength and functional capacity in older adults. Thirty-six healthy older adults (aged 68.2 ± 5.3 y) undertook isokinetic dynamometry for isometric and isokinetic concentric knee extensor strength, the 6-m fast walk, timed up and go, stair climb and descent and vertical jump tests. Longitudinal brightness-mode ultrasound scans (probe frequency, 10 MHz) of the vastus lateralis, vastus intermedius, rectus femoris and gastrocnemius medialis were obtained, and muscle architecture measures (thickness, fascicle pennation angle and fascicle length) were correlated with the aforementioned strength and functional measures. Quadriceps thickness was a significant (p < 0.05) independent predictor of isometric and isokinetic knee extensor strength (R2 ≥ 0.630). Gastrocnemius medialis thickness was a significant independent predictor of 6-m fast walk test (R2 = 0.216, p < 0.05), timed up and go test (R2 = 0.455, p < 0.01), stair climb power (R2 = 0.591, p < 0.01), stair descent power (R2 = 0.608, p < 0.01) and vertical jump height (R2 = 0.579, p < 0.01). Ultrasound is a safe, non-invasive and efficient tool for inferring the strength and functional capacity of older adults.