Shawn M. Allen1, Stephanie A. Sontag1, Sergio Perez1, Alex A. Olmos1, Sunggun Jeon1, Jeremy Lippman2, Michael A. Trevino1

1Oklahoma State University, Stillwater, OK; 2University of Kanas, Lawrence, KS

PURPOSE: The purpose of this study was to examine possible relationships among maximal strength of the knee extensors with measures of muscle composition and architecture from the vastus lateralis (VL) in untrained individuals. METHODS: Seven healthy males (means ± SD; age: 19.29 ± 0.76 years; height: 177.86 ± 4.78 cm; body mass: 77.81 ± 10.33 kg) twelve healthy females (means ± SD; age: 21.56 ± 3.20 years; height: 164.33 ± 6.36 cm; body mass: 58.63 ± 10.00kg) volunteered for this investigation. All subjects reported no structured forms of physical activity for the previous 3 years. Real-time brightness mode (B-mode) ultrasonography was used to measure pennation angle, muscle thickness, subcutaneous fat, echo intensity corrected for subcutaneous fat, and muscle quality (muscle thickness/echo intensity) of the VL. The ultrasound scans were taken at the midpoint of the anterior superior iliac spine and the superior border of the patella on the right leg. Water-soluble transmission gel was applied generously to the multi-frequency linear array probe to enhance acoustic coupling and reduce possible near-field artifacts. Following the ultrasound scans, participants performed three maximal voluntary contractions of the knee extensors (MVC) on a biodex isokinetic dynamometer, and the highest torque output was selected as the MVC. Pearson’s product moment correlation coefficients were calculated comparing MVC of the knee extensors with pennation angle, muscle thickness, echo intensity, and muscle quality of the VL. Alpha was set at 0.05. RESULTS: MVC of the knee extensors was not correlated with pennation angle (p = 0.178, r= 0.355), muscle thickness (p = 0.179, r = 0.354), echo intensity (p = 0.084, r = -0.445), or muscle quality (p = 0.056, r = 0.487). CONCLUSIONS: Previous relationships have been reported for muscle composition and architecture of the quadriceps muscles with maximal strength of the knee extensors for recreationally active and chronically trained individuals. However, for a cohort of college-aged sedentary individuals, there were no relationships between MVC and any of the examined variables. It is possible that muscle morphological and/or neural adaptations that occur with exercise are necessary for these relationships to exist.

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