Sergio Perez Jr.1, Stephanie A. Sontag1, Trent J. Herda2, Adam J. Sterczala3, Jonathan D. Miller2, Mandy E. Parra4, Hannah L. Dimmick5, Michael A. Trevino1

1Oklahoma State University, Stillwater, Oklahoma; 2University of Kansas, Lawrence, Kansas; 3University of Pittsburg, Pittsburg, Pennsylvania; 4University of Mary Hardin-Baylor, Belton, Texas; 5University of Calgary, Calgary, Alberta

PURPOSE: The purpose of this study was to examine if relationships exist between muscle architecture and mechanomyographic amplitude (MMGRMS)-torque relationships of the vastus lateralis (VL). METHODS: 11 healthy males (means ± SD; age: 20.18 ± 2.04 years; height: 178.51 ± 4.28 cm; body mass: 78.63 ± 9.11 kg) and 12 healthy females (age: 21.33 ± 3.00 years; height: 164.58 ± 6.60 cm; body mass: 60.38 ± 10.24 kg) completed this investigation. B-mode ultrasonography was used to measure pennation angle, muscle thickness, and subcutaneous fat (sFAT) of the VL. Subjects performed three, three-second maximal voluntary contractions (MVCs) of the knee extensors on an isokinetic dynamometer and the highest torque output was designated as the MVC. A MMG sensor was placed on the VL. Participants then performed an isometric submaximal muscle action that included a 7 s linearly increasing segment up to 70% MVC and a 12 s plateau. For the linearly increasing segment, linear regressions models were fit to the log-transformed MMGRMS-torque relationships and the slope (b term) was calculated. MMGRMS was averaged during the steady torque segment. Pearson’s product moment correlation coefficients were calculated comparing the b terms and MMGRMS at steady torque to pennation angle, muscle thickness, and sFAT of the VL. Alpha was set at 0.05. RESULTS: The b terms were significantly correlated with pennation angle (p < 0.001, r = 0.772) and muscle thickness (p = 0.004, r = 0.571), but not with sFAT (p = 0.263). In addition, MMGRMS at steady torque was significantly correlated with pennation angle (p = 0.018, r = 0.500) and muscle thickness (p = 0.014, r = 0.515), but not with sFAT (p = 0.154). CONCLUSION:The mechanical behavior of the muscle, as measured with MMGRMS, was sensitive to differences in pennation angle and muscle thickness of the VL during a high-intensity contraction. MMGRMS may provide a relatively simple measurement to obtain information regarding muscle architecture. Future research should investigate if MMGRMS can quantify potential changes in pennation angle and muscle thickness as a result of exercise training, aging, or disease.

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