Second Review Report on Saturday 27th October 2018 Despite I am not convinced about 25 markers of actual child's body as translated into figure 1B using stick figure, I am going to endorse this publication due to novelty of the approach. Since authors claim that this is an initial study, it is justifiable to endorse this publication subject to future focus on those 25 markers with its purpose than having many markers on the body.

Revised Review Report on Saturday 20th October 2018 While authors have significantly improved the sections, it is essential to improve Figure 1: . Child walking on the GRAIL system during the session. Markers placed on body segments are not clear with reference to Saggital plane. The inclusion of Figure 2 with stick figure provides insight into motion analysis done, but the clarity of the actual experiment carried out in Figure 1 still should be clear for readers.

Reviewer Report Major findings: 1. Children with ASD had reduced ankle flexion moment, greater hip flexion at the initial contact, and greater pelvic anteversion. After the discrete gait perturbation, variations of peak of knee extension significantly differed between groups and correlated with the severity of autistic core symptoms. Throughout perturbation trials, more than 60% of parameters showed reliable adaptation with a decay rate comparable between groups. 2. Authors found out gait peculiarities in children with ASD, including both kinetic and kinematic features; a motor adaptation comparable to their TD peers, even though with an atypical pattern; and a motor adaptation rate comparable to TD children but involving different aspects of locomotion. The platform showed its usability with children with ASD and its reliability in the definition of paradigms for the study of motor learning while doing complex tasks, such as gait. The additional possibility to accurately manipulate visual and proprioceptive feedback will allow researchers to systematically investigate motor system features in people with ASD. Limitations: 1. Authors have not explored recent articles which dealt with comprehensive analysis of kinematics features in all 3 planes using 3-D Human Motion Analysis System. They rely only on ASD articles with no such comprehensive analysis in the introduction. 2. Authors failed to consider Range of Motion (ROM) in all 3 planes for hip, knee and ankle. In the table 2, it is not clear at all which plane they consider for ROM. Strengths: 1. Authors used integrated instrumentation system for ASD. The use of Virtual Reality (VR) is a significant inclusion. 2. Research outcomes will open new avenues of research for ASD Improvements to be carried out: 1. As per abstract written, why didn't consider Range of Motion (ROM) in all planes despite used 3-D Motion Analysis System? Authors would have considered ROM in hip, knee and ankle based on the markers placed. It seems, authors considered ROM, but what went wrong with results related to ROM. As per previous literature ROM plays significant role for ASD. 2. In the introduction, authors just explored articles related to ASD with no articles dealt with recent advancements in 3-D motion analysis systems employed using critical kinematics parameters. Even though these articles are specifically addressed ASD, kinematic analysis done using 3-D motion analysis system is still valid for the objectives addressed in this article as below;

(i) Instrumented measurement analysis system for soldiers’ load carriage movement using 3-D kinematics and spatio-temporal features, Measurement, Volume 95, January 2017, Pages 230-238. (ii) “Intelligent Musculosoccer Simulator”, pp. 409-414, The Impact of Technology on Sport II, Taylor & Francis, ISBN: 978-0-415-45695-1, London, 2007. 3. In the experimental protocol line no 170, did authors consider an exact percentage of gait cycle for stance phase? If so, why not mentioned here? if not, justify the same. 4. In the experimental protocol line no 172, Is this ROM in all 3 planes? Why not mentioned in the abstract? Was not significant? If ROM was measured in all 3 planes, it would have been significant at least in one plane for ASD. If not, why not? 5. From the table 2, it is not clear whether authors considered all 3 planes for kinematics. As per reference 1 suggested under the comments in the introduction, authors should consider including all 3 planes, in particular for ROM.