Applied Physiology, Nutrition, and Metabolism, Ahead of Print.
Ultrasonography-derived cross-sectional area (CSA) and echo intensity (EI) are increasingly utilized by investigators to study muscle size and quality, respectively. We sought to examine age, sex, and region (proximal, middle, distal) differences in vastus lateralis and rectus femoris CSA and EI, and determine whether correction for subcutaneous fat thickness influences the magnitude of EI differences. Fifteen younger men (mean age = 23 years), 15 younger women (aged 21 years), 11 older men (aged 74 years), and 15 older women (aged 70 years) participated. Clear differences were observed among age, sex, and region for vastus lateralis CSA (p ≤ 0.013, d = 0.38–0.73), whereas rectus femoris CSA was only different between younger and older participants at the proximal region (p = 0.017, d = 0.65). Uncorrected EI was greatest at the distal region of both muscles (p < 0.001, d = 0.59–1.38), with only the younger men having significantly lower EI values than the other groups (p ≤ 0.043, d = 0.37–0.63). Subcutaneous fat correction resulted in a marked increase in the magnitude of sex-specific EI differences (p ≤ 0.032, d ≥ 0.42). Additionally, subcutaneous fat correction increased the uniformity of EI throughout the thigh. These findings highlight considerable region-specific differences in muscle size and quality among younger and older men and women and highlight the need to correct for subcutaneous fat thickness when examining EI. Novelty Rectus femoris CSA is similar between younger and older adults except at the most proximal site evaluated. Age- and sex-specific differences in uncorrected EI are nonuniform across the thigh. Correction for subcutaneous fat thickness substantially increased EI in women, resulting in greater sex differences.

中文翻译：

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骨骼肌大小和质量的年龄、性别和区域特异性差异。

应用生理学、营养学和代谢，提前出版。
研究人员越来越多地利用超声衍生的横截面积 (CSA) 和回声强度 (EI) 来分别研究肌肉大小和质量。我们试图检查股外侧肌和股直肌 CSA 和 EI 的年龄、性别和区域（近端、中间、远端）差异，并确定皮下脂肪厚度的校正是否会影响 EI 差异的大小。15 名年轻男性（平均年龄 = 23 岁）、15 名年轻女性（21 岁）、11 名年长男性（74 岁）和 15 名年长女性（70 岁）参加。在年龄、性别和地区之间观察到股外侧肌 CSA 的明显差异（p ≤ 0.013，d = 0.38-0.73），而股直肌 CSA 仅在近端区域的年轻和年长参与者之间存在差异（p = 0.017，d = 0.65）。未矫正的 EI 在两条肌肉的远端区域最大（p < 0.001，d = 0.59-1.38），只有年轻男性的 EI 值显着低于其他组（p ≤ 0.043，d = 0.37-0.63）。皮下脂肪校正导致性别特异性 EI 差异的幅度显着增加（p ≤ 0.032，d ≥ 0.42）。此外，皮下脂肪矫正增加了整个大腿的 EI 均匀性。这些发现突出了年轻和老年男性和女性肌肉大小和质量的显着区域特异性差异，并强调了在检查 EI 时校正皮下脂肪厚度的必要性。新奇股直肌 CSA 在年轻人和老年人之间是相似的，除了在最近的评估部位。未矫正 EI 的年龄和性别特异性差异在大腿上是不均匀的。