Repeatability and Reproducibility of Postural Variables by Photogrammetry Cláudia Tarragô Candotti, PhD, Grazielle Martins Gelain, BSc(Chiro), Arthur Antoniolli, MS, Liliane Martini Araújo, MS, Adriane Vieira, PhD, and Jefferson Fagundes Loss, PhD ABSTRACT Objective: This study aimed to examine the reliability of postural variables analyzed by photogrammetry obtained at different instances on the same day and between 2 different days. Methods: A sample composed of 24 healthy adult individuals of both sexes was submitted to photogrammetric postural assessment. From 35 seconds of filming, 7 photographs (of time instance at 0 second, 05 seconds, 10 seconds, 15 seconds, 20 seconds, 25 seconds, and 30 seconds) were extracted and digitalized on digital image-based postural assessment software. One factor repeated-measures analysis of variance quantified the alterations in the magnitude of the variables within and between sessions (factor time and factor day, respectively). The intraclass correlation coefficient (ICC), standard error of measurement (SEM), and minimal detectable change (MDC) were calculated to verify the repeatability and reproducibility. Results: The repeatability shows that postural variables did not present significant differences in the comparison among the 7 instances; all the variables had excellent and significant ICCs, and SEM and MDC values indicated measurement errors lower than 5%. The intrarater reproducibility shows that postural variables did not present significant differences between 2 days of evaluation; most of the variables had excellent and significant ICCs, and SEM and MDC values were between 0.9% and 12.5%. Conclusion: The results for repeatability and reproducibility show that most of the variables have excellent and significant ICCs. Postural evaluation by photogrammetry can be performed at any time within a 30-second interval counting from the positioning of the participant for assessment. Therefore, we conclude that a single photograph can represent the static posture of an individual in the postural evaluation, which is reliable enough and useful to determine the effects of an intervention either in clinical practice or in research. (J Manipulative Physiol Ther 2019;xx:1-xxx) Key Indexing Terms: Posture; Standing Position; Photogrammetry; Reproducibility of Results INTRODUCTION Photogrammetry is defined by the American Society for Photogrammetry and Remote Sensing as the art, science, and technology of obtaining reliable information about physical objects and the environment through processes of recording, measuring, and interpreting images. 1 The use of photogrammetry as a tool for postural assessment has been defended by many researchers 2-10 because it is a relatively simple and objective method that presents accurate and precise results. 5,9-12 Postural variability assessed by photogrammetry has been investigated. McEvoy and Grimmer 6 evaluated school-age children at 2 distinct times within 1 hour, and Stolinski et al, 9 also evaluating children, repeated the assessment 1 hour and 1 week after the first evaluation. Refshauge et al 13 evaluated 3 measurements on the cervical spine and repeated the assessment with a 1-minute interval on the same day and on distinct days. In all cases, a single photograph was used in each evaluation. It is established that the upright standing posture is not completely static, and changes occur in short intervals of time 14,15 when evaluated using the center of pressure. 14,16,17 However, to the best of our knowledge, no studies have attempted to evaluate changes in the result of postural assessment from consecutive photographs. Considering that photogrammetry conventionally uses only a single photo (representative of a single instance), it is questionable whether the postural variables extracted from that moment are affected by time. Therefore, the objectives of this study were as follows: (1) to compare the outcomes of a postural assessment (by means of photogrammetry) obtained at different instances on the same day and on different days, and Physical Education, Physiotherapy and Dance School of Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil. Corresponding author: Grazielle Martins Gelain, BSc(Chiro), ESEFID/LAPEX/BIOMEC, Rua Felizardo, 750, Porto Alegre, RS, CEP 90450-190, Brazil. Tel.: +55 51 98151 7527. (e-mail: graziellegelain@gmail.com). Paper submitted May 9, 2018; in revised form October 1, 2018; accepted October 21, 2018. 0161-4754 © 2019 by National University of Health Sciences. https://doi.org/10.1016/j.jmpt.2018.10.006