Validity, reliability and measurement error of quadriceps femoris muscle thickness obtained by ultrasound in healthy adults: a systematic review

Abstract

Abstract Due to its low cost and operational simplicity, ultrasound has been used to monitor muscle thickness in laboratory environments, rehabilitation clinics, and sports clubs. However, it is necessary to determine the measurement's quality to infer whether the possible changes observed are derived from the treatment or the measurement error. Therefore, we performed a systematic review to determine the validity, reliability, and measurement error of quadriceps femoris muscle thickness obtained by ultrasound in healthy adults. A search was conducted in the Pubmed, Scopus, and Web of Science databases until April 2022. The study selection process was carried out by two independent researchers, with the presence of a third researcher in case of disagreements. Twenty-six studies were eligible for the review, being 4 of validity, 4 of reliability only, and 18 of reliability and measurement error. The intraclass correlation coefficient ranged from 0.60 to 0.99 in validity studies and from 0.44 to 0.99 in reliability studies. The typical error of measurement ranged from 0.01 to 0.47 cm, and the coefficient of variation was from 0.5 to 17.9%. Four studies received “very good” classification in all the risk of bias analysis criteria. Therefore, it is concluded that the quadriceps femoris muscle thickness obtained by ultrasound was shown to be valid, reliable, and to have low measurement errors in healthy adults. The weighted average of the relative error was 6.5%, less than typical increases in resistance training studies. The raters' experience and methodological care for repeated measurements were necessary to observe low measurement errors.