Numerous studies have corrected the echo intensity of the vastus lateralis for subcutaneous fat thickness. However, it is unclear if correction for subcutaneous fat improves the correlation between vastus lateralis echo intensity and physical performance. We aimed to examine the correlations between vastus lateralis muscle morphology parameters and physical performance outcomes in older women. Twenty healthy older women (67 ± 4 years) participated in this study. Muscle cross‐sectional area, raw and corrected echo intensity and subcutaneous fat thickness were determined from ultrasound scans of the vastus lateralis. Physical performance was assessed from timed up‐and‐go and 6 min walk tests. Raw echo intensity was significantly related to timed up‐and‐go scores (r = 0.552, p = 0.012) and 6 min walk distance (r = −0.462, p = 0.040), whereas corrected echo intensity was not significantly associated with these performances (r = 0.433, p = 0.056 and r = −0.373, p = 0.105). There was a nonsignificant correlation between raw echo intensity and subcutaneous fat thickness (r = 0.353, p = 0.126). There were also nonsignificant correlations between muscle cross‐sectional area and timed up‐and‐go scores (r = −0.189, p = 0.426) and 6 min walk distance (r = 0.298, p = 0.201). The results of our study showed that raw echo intensity correlated better than corrected echo intensity with physical performance. These findings question the need to correct the echo intensity of the vastus lateralis for subcutaneous fat thickness in older adults.

This study aimed to examine the effects of age on hip flexion maximal and rapid strength and rectus femoris (RF) muscle size and composition in men. Fifteen young (25 [3] y) and 15 older (73 [4] y) men performed isometric hip flexion contractions to examine peak torque and absolute and normalized rate of torque development (RTD) at time intervals of 0 to 100 and 100 to 200 milliseconds. Ultrasonography was used to examine RF muscle cross-sectional area and echo intensity. Peak torque, absolute RTD at 0 to 100 milliseconds, and absolute and normalized RTD at 100 to 200 milliseconds were significantly lower (P = .004–.045) in the old compared with the young men. The older men exhibited lower cross-sectional area (P = .015) and higher echo intensity (P = .007) than the young men. Moreover, there were positive relationships between cross-sectional area and absolute RTD at 0 to 100 milliseconds (r = .400) and absolute RTD at 100 to 200 milliseconds (r = .450) and negative relationships between echo intensity and absolute RTD at 100 to 200 milliseconds (r = −.457) and normalized RTD at 100 to 200 milliseconds (r = −.373). These findings indicate that hip flexion maximal and rapid strength and RF muscle size and composition decrease in old age. The relationships observed between ultrasound-derived RF parameters and measurements of RTD suggest that these age-related declines in muscle size and composition may be relevant to hip flexion rapid torque production.

Objective: Isometric peak torque (PT) and rate of torque development (RTD) are important characteristics relevant to athletic performance. A novel device called the Dynamo Torque Analyzer calculates and displays real-time measurements of isometric PT and RTD. However, the ability of the Dynamo to provide valid and reliable isometric PT and RTD measurements similar to those of an isokinetic dynamometer remains unclear. This study aimed to compare the reliability and magnitude of isometric leg extension and flexion PT and RTD measurements between an isokinetic dynamometer and the Dynamo Torque Analyzer. Approach: Twenty healthy, recreationally-active adults (age = 22 ± 3 years; height = 169 ± 10 cm; mass = 71 ± 18 kg) performed three isometric leg extension and flexion maximal voluntary contractions on two different occasions, from which isometric PT and early (RTD100), late (RTD200), and maximum (Peak RTD) RTD characteristics were measured by an isokinetic dynamometer and the Dynamo. Main results: Isometric leg extension and flexion PT and RTD characteristics were highly consistent across sessions for both the isokinetic dynamometer and Dynamo devices, with intraclass correlation coefficients of 0.935–0.984 and standard errors of measurement expressed as a percentage of the mean of 4.93–14.46%. There were significant positive relationships between the isokinetic dynamometer and Dynamo for all PT and RTD characteristics (r ≥ 0.994; P < 0.001). Moreover, no significant differences between devices were observed for these variables (P = 0.107–0.555). Significance: These findings suggest that the Dynamo Torque Analyzer may be a valid and reliable device for measuring isometric PT and RTD of the lower-body musculature.

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