Ultrasound measurements of skeletal muscle architecture are associated with strength and functional capacity in older adults

This study aimed to determine whether ultrasound measures of muscle architecture can infer strength and functional capacity in older adults. Thirty-six healthy older adults (age 68.2 ± 5.3 years) undertook isokinetic dynamometry for isometric and isokinetic concentric knee extensor strength, the 6 metre fast walk (6mFWT), timed up and go (TUG), stair climb and descent, and vertical jump tests. Longitudinal brightness-mode ultrasound scans (probe frequency 10MHz) 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 above 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 6mFWT (R2 = 0.216; P < 0.05), TUG (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