Michael J. Scharville

Reliability of panoramic ultrasound imaging to simultaneously examine muscle size and quality of the medial gastrocnemius

Introduction: In this study we examined the test–retest reliability of panoramic brightness‐mode ultrasound (US) imaging to simultaneously measure both muscle size and quality from a single US image. Methods: Sixteen healthy, recreationally active men (age = 20.9 ± 2.5 years) volunteered for this investigation. Test–retest reliability was evaluated using intraclass correlation coefficients (ICCs) and the standard error of measurement as a percentage of the mean (SEM%). Muscle size [cross‐sectional area (CSA)], and muscle quality [echo intensity (EI)] of the medial gastrocnemius were examined on 2 separate days. Results: These measures demonstrated acceptable reliability between assessment days with ICCs and SEM% of 0.914 and 0.720 and 5.830 and 3.680 for CSA and EI, respectively. Conclusions: These results suggest that panoramic US imaging may be a reliable technique for simultaneous assessment of both muscle size and quality from a single US scan. Muscle Nerve 49: 736–740, 2014

Test-retest reliability and the minimal detectable change for achilles tendon length: a panoramic ultrasound assessment.

The purpose of the present study was to examine test-retest reliability and minimal detectable change (MDC) values for Achilles tendon (AT) length determined using panoramic ultrasound (US) imaging. Seventeen men (age = 21.0 ± 2.3 y) visited the laboratory on two separate days, where AT length was examined along the mid-longitudinal axis of the right lower leg with a portable B-mode panoramic US device. These measures were found to have acceptable reliability with intra-class correlation coefficient (ICC) and standard error of measurement (SEM) values of 0.954 and 4.43 mm (SEM% of the mean = 2.37%), respectively. In addition, the MDC for the panoramic US assessment of AT length was 12.27 mm (MDC% of the mean = 6.57%). These findings suggest that panoramic US imaging is a reliable technique for detection of clinically relevant changes in AT length and may therefore be a practical and time-efficient clinical tool for future studies examining AT length in vivo.

Neural and muscular contributions to the age-related reductions in rapid strength

Introduction The purposes of this study were to investigate the age-related differences in absolute and normalized plantarflexion rate of torque development (RTD) at early (0–50 ms) and late (100–200 ms) time intervals and to examine specific neural and muscular mechanisms contributing to these differences. Methods Thirty-two young (20.0 ± 2.1 yr) and 20 older (69.5 ± 3.3 yr) recreationally active men performed rapid plantarflexion isometric muscle actions to examine absolute and normalized RTD and muscle activation using EMG at early and late time intervals. Ultrasonography was used to examine medial gastrocnemius muscle size, echo intensity (EI), and muscle architecture (fascicle length [FL] and pennation angle [PA]). Results The older men were weaker (23.9%, P < 0.001) and had lower later absolute and normalized RTD (P = 0.001–0.034) variables when compared with the young men. The older men also had higher EI (P < 0.001), smaller PA (P = 0.004), and lower later EMG amplitude values (P = 0.009–0.046). However, there were no differences in early RTD and EMG amplitude values, muscle size, or FL between groups (P = 0.097–0.914). Lower late RTD values were related to higher EI, smaller PA, and lower EMG amplitude values (r = −0.28–0.59, P = 0.001–0.044); however, late RTD values were no longer related to PA after normalizing to peak torque. Conclusions Age-related alterations in muscle quality (EI), architecture, and muscle activation may influence rapid torque production at late time intervals (≥100 ms) from contraction onset. These findings highlight specific neuromuscular factors that influence the age-related reductions in RTD, which has been shown to significantly influence function and performance in older adults.

Pennation Angle Does Not Influence the Age-Related Differences in Echo Intensity of the Medial Gastrocnemius

The reflection of an ultrasound (US) wave is strongest when the propagation direction of the wave is perpendicular to muscle fascicles. Thus, it is possible that muscle echo intensity (EI), a gray-scale US measure of muscle quality, may be influenced by the angulation of muscle fascicles. Therefore, the purpose of this study was to determine if age-related differences in muscle EI values are influenced by differences in pennation angle (PA). Medial gastrocnemius EI and PA were examined using panoramic US imaging in 24 young (19.8 ± 1.7 y) and 21 older (69.3 ± 3.3 y) men. The young men had lower EI values (young = 74.1 ± 6.3 a.u., older = 89.1 ± 8.8 a.u.) and a greater PA (young = 20.0 ± 2.9°; older = 17.2 ± 2.5°) compared with the older men (p < 0.01). In addition, there was a negative relationship (r = -0.473, p < 0.01) between PA and EI with both groups combined, but no significant relationship when the young (r = -0.334, p = 0.111) and older (r = -0.147, p = 0.525) men were examined separately. An analysis of covariance revealed that muscle EI values remained different (p < 0.01) between age groups after adjustment for differences in PA. Thus, after statistically adjusting the mean EI values for the differences in PA, there were still significant age-related differences in EI. These findings may provide further support that the age-related changes in muscle EI values reflect changes in tissue composition (i.e., increase in intramuscular fat and/or connective tissue) commonly reported in older adults.