Echo intensity (EI) is being increasingly utilized by investigators as an index of skeletal muscle quality. Previous studies have reported independent associations between EI versus both age and muscle strength.

Purpose

We sought to determine whether EI is more strongly associated with age or strength.

Methods

Twenty-eight younger adults (13 men, 15 women; mean age = 22 years) and 25 older adults (10 men, 15 women; age = 71 years) participated. B-mode ultrasonography was utilized to acquire images of the vastus lateralis and rectus femoris. ImageJ software was used to quantify corrected EI and muscle cross-sectional area (CSA). Each participant performed 40 maximal concentric isokinetic muscle actions of the knee extensors (velocity = 180°·s⁻¹). The mean peak torque of the best three attempts was used to quantify muscle strength. Specific torque was calculated as strength relative to CSA. Fatigability was also quantified. Statistical analyses included independent samples t-tests and stepwise regression.

Results

There were large differences between age groups for strength (p < .001, d = 1.831) and CSA (p = .003, d = 0.872). When corrected for subcutaneous tissue thickness, the difference in EI between age groups was small (p = .184, d = 0.371). Stepwise regression revealed that muscle strength was the single best predictor of EI (R² = 0.206), with age, CSA, specific torque, and fatigability explaining no unique variance.

Conclusion

Concentric isokinetic muscle strength is a better predictor of EI than age.

中文翻译：

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肌肉力量而非年龄解释了回声强度的独特变化。

回声强度（EI）被研究人员越来越多地用作骨骼肌质量的指标。先前的研究报道了EI与年龄和肌肉力量之间的独立关联。

目的

我们试图确定EI是否与年龄或力量更紧密相关。

方法

参加调查的有28名年轻成年人（13名男性，15名女性；平均年龄= 22岁）和25名年龄较大的成年人（10名男性，15名女性；年龄= 71岁）。B型超声检查用于获取股外侧肌和股直肌的图像。使用ImageJ软件量化校正后的EI和肌肉横截面积（CSA）。每个参与者都进行了40次膝盖伸肌的最大同心等速肌动作（速度= 180°·s ^-1）。最好的三个尝试的平均峰值扭矩用于量化肌肉力量。将比扭矩计算为相对于CSA的强度。易疲劳性也被量化。统计分析包括独立样本t检验和逐步回归。

结果

年龄段的强度（p  <.001，d  = 1.831）和CSA（p  = .003，d  = 0.872）之间存在很大差异。校正皮下组织厚度后，不同年龄组之间的EI差异很小（p  = .184，d  = 0.371）。逐步回归表明，肌肉力量是EI的最佳预测指标（R ²  = 0.206），年龄，CSA，比扭矩和易疲劳性没有唯一的差异。

结论

同心等速肌力比年龄更好地预测EI。