Jandova Tereza, Kinkorova Ivana, Vetrovsky Tomas, Mala Jitka, Musilova Evelyn, Steffl Michal, Narici Marco V
Charles University, Faculty of Physical Education and Sport, Prague, Czech Republic.
Charles University, Faculty of Physical Education and Sport, Prague, Czech Republic
BMJ Open. 2025 Sep 26;15(9):e100495. doi: 10.1136/bmjopen-2025-100495.
Ultrasonography is a non-invasive and safe method for assessing muscle morphology. Among its parameters, echo intensity (EI), derived from grayscale image analysis, has emerged as a promising indicator of muscle quality and intramuscular fat infiltration. This study aims to validate EI as a marker for evaluating muscle quality in a population of Czech children, through integration with gold-standard assessments of muscle strength and body composition. The primary aim of this study is to assess the reliability and construct validity of quadriceps muscle EI using ultrasound as a proxy measure of morphological muscle quality in children aged 10-14 years.
Children aged 10-14 years will undergo ultrasound assessment of the quadriceps femoris (QF). EI will be derived from longitudinal scans of each QF head and the cross-sectional area (CSA) from panoramic mid-thigh images. Muscle function will be assessed as maximal voluntary contraction (MVC) of isometric knee extension with muscle quality expressed as MVC/CSA. A 30 s sit-to-stand test (30STS) will be used as an additional functional measure. EI reliability (intra-rater, inter-rater and test-retest) will be evaluated with intraclass correlation coefficients (ICC), Bland-Altman plots and complementary indices. Exploratory known-groups validity will be tested by comparing EI between weight-status groups. Control variables include dual-energy X-ray absorptiometry (DXA)-derived body composition, skeletal age (as determined by DXA hand scans) and physical activity (assessed using 7-day accelerometry).This study will include 200 children (100 girls and 100 boys) aged 10-14 years using an a priori power analysis based on the primary objective of assessing construct validity through multiple linear regression, assuming an alpha level of 0.05 and 80% power. Participants will be recruited from paediatric outpatients of the Paediatric Obesity Clinic and individuals reached through a recruitment campaign. Inclusion criteria require general good health, while exclusion criteria include a history or symptoms of cardiovascular, pulmonary, metabolic or neurological disease, as well as the use of over-the-counter or prescribed medications. Informed consent and assent will be obtained from all participants.Reliability of ultrasound-derived EI will be assessed for intra-rater, inter-rater and test-retest agreement using ICC coefficients, Bland-Altman plots and complementary indices such as SE of measurement, coefficient of variation and minimal detectable change at 95% CI, following Consensus-based Standards for the selection of health Measurement Instruments guidelines. Construct validity will be examined by modelling associations between EI and functional muscle quality (MVC/CSA), with 30STS as an additional functional measure. Known-groups validity will be tested by comparing EI across weight groups, using generalised linear regression models adjusted for skeletal age, body composition and physical activity. All validity analyses will be conducted separately for girls and boys. Ultrasound-derived EI of the QF is expected to show high reliability (ICC≥0.80) and acceptable test-retest reproducibility. Construct validity should be supported by moderate associations with functional muscle quality (MVC/CSA), while known-groups validity is expected to reveal higher EI values in children with obesity and/or insufficient physical activity.
The study will be conducted in accordance with the Declaration of Helsinki and was approved by the Ethics Committee of the Faculty of Physical Education and Sport, Charles University (EK 101/2024). Written parental consent and verbal assent from children will be obtained, with all data handled confidentially and anonymised. Results will be disseminated transparently to participants and their families in line with ethical principles of respect, beneficence and justice.
NCT06792279.
超声检查是一种评估肌肉形态的非侵入性安全方法。在其各项参数中，通过灰度图像分析得出的回声强度（EI）已成为肌肉质量和肌内脂肪浸润的一个有前景的指标。本研究旨在通过与肌肉力量和身体成分的金标准评估相结合，验证EI作为评估捷克儿童群体肌肉质量的标志物。本研究的主要目的是评估超声测量10 - 14岁儿童股四头肌EI作为肌肉形态质量替代指标的可靠性和结构效度。
10 - 14岁儿童将接受股四头肌（QF）的超声评估。EI将从每个QF头肌的纵向扫描中得出，横截面面积（CSA）则从大腿中部全景图像中获取。肌肉功能将通过等长膝关节伸展的最大自主收缩（MVC）进行评估，肌肉质量用MVC/CSA表示。30秒坐立试验（30STS）将作为一项额外的功能测量。EI的可靠性（评估者内、评估者间和重测）将使用组内相关系数（ICC）、布兰德 - 奥特曼图和补充指标进行评估。探索性已知组效度将通过比较不同体重状态组之间的EI来检验。控制变量包括双能X线吸收法（DXA）得出的身体成分、骨龄（通过DXA手部扫描确定）和身体活动（使用7天加速度计评估）。本研究将纳入200名10 - 14岁儿童（100名女孩和100名男孩），基于通过多元线性回归评估结构效度的主要目标进行先验功效分析，假设α水平为0.05，功效为80%。参与者将从儿科肥胖诊所的儿科门诊患者以及通过招募活动找到的个体中招募。纳入标准要求总体健康状况良好，排除标准包括心血管、肺部、代谢或神经系统疾病的病史或症状，以及使用非处方或处方药物。将获得所有参与者的知情同意和同意书。根据基于共识的健康测量仪器选择标准指南，使用ICC系数、布兰德 - 奥特曼图和补充指标（如测量标准误、变异系数和95%置信区间的最小可检测变化）评估超声得出的EI的评估者内、评估者间和重测一致性的可靠性。将通过建立EI与功能性肌肉质量（MVC/CSA）之间的关联模型来检验结构效度，30STS作为一项额外的功能测量。已知组效度将通过比较不同体重组之间的EI来检验，使用针对骨龄、身体成分和身体活动进行调整的广义线性回归模型。所有效度分析将分别针对女孩和男孩进行。预计QF的超声得出的EI将显示出高可靠性（ICC≥0.80）和可接受的重测重复性。结构效度应由与功能性肌肉质量（MVC/CSA）的中度关联支持，而已知组效度预计将揭示肥胖和/或身体活动不足儿童的EI值更高。
本研究将按照《赫尔辛基宣言》进行，并获得了查理大学体育与运动学院伦理委员会（EK 101/2024）的批准。将获得家长的书面同意和儿童的口头同意，所有数据将保密并匿名处理。结果将根据尊重、受益和公正的伦理原则透明地传达给参与者及其家人。
NCT06792279。
