J.G. Moore1, A.C. D’Lugos2, J.J. Dickinson1, L.J. D’Acquisto1, J.M. Dickinson, FACSM1

1Central Washington University, Ellensburg, WA, 2University of Florida, Gainesville, FL

Advancing age is accompanied by changes in the structure and composition of skeletal muscle. Ultrasound (US) represents a practical and non-invasive strategy to assess differences/changes in skeletal muscle composition through the examination of echogenicity (EG), or the grayscale/brightness of the image. PURPOSE: To 1) identify the extent to which US can detect differences between young and older adults in quadriceps muscle EG, and 2) determine how imaging site/anatomical location impacts the comparison between young and older adults. METHODS: Two dimensional images of the quadriceps (right leg) from young (26±4yr, n=8M, 8F) and older (70±7yr, n=7M, 5F) healthy adults were captured using B-mode ultrasound (Terason 3300). From each participant, five images of the quadriceps muscles were collected from anatomical sites along the anterior and lateral plane of the leg corresponding to 59% femur length, 39% femur length, and 22% femur length. All images were collected with the participant in the supine position. EG analyses (Image J, value range: 0=Black, 255=White) were performed on anterior images for the rectus femoris (RF), anterior images for the vastus intermedius (AVI), lateral images for the vastus intermedius (LVI), and lateral images for the vastus lateralis (VL). RESULTS: Collapsed across all imaging sites and muscles, older adults showed a higher (P<0.05) average EG compared to young (53.7±11.1 vs. 39.6±18.3). For the individual muscles, older adults had higher average EG (P<0.05) for both AVI (58.1±10.9 vs. 40.0±11.0) and LVI (54.4±14.1 vs. 37.1±20.5), however, no differences were observed for average EG of the RF or VL (P>0.05). Specific to each imaging site, differences (P<0.05) between young and older adults were found at 0/2 imaging sites for the RF, 4/5 imaging sites for the VI, and 1/3 imaging sites for the VL. CONCLUSION: These data indicate that US is able to detect differences in EG/composition between muscle of young and older adults, however, differences were not homogenous among the quadriceps muscles. Future research should couple US-based measures with functional/clinical based outcomes to better understand the role that EG assessment can provide in regard to muscle health and function.

Supported by CWU School of Graduate Studies and Research

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