The effects of video-modeling to improve upper body posture during screen-based device use among adolescent students in special schools for mild grade intellectual disability : a randomized controlled trial

Abstract

Background: Longitudinal evidence showed that screen-based device use might significantly lead to musculoskeletal (MS) pain associated with the posture assumed among adolescents. On the other hand, cross-sectional evidence showed that the device use were not significantly different between those who had intellectual disability (ID) and/or autism spectrum disorder (ASD) and those who were typically developing. Nevertheless, there was no clear evidence of the effects of skill training on optimal posture during screen-based device use among adolescents belonging to class of mild ID with or without ASD. Video-modeling (VM) for skill training had been extensively investigated in case studies of children and adolescents with ID and/or ASD. Nonetheless, the qualities of the results were mixed. Aim: The aim of this randomized controlled trial (RCT) is to examine the effects of video-modeling in improving upper body posture during screen-based device use among adolescents belonging to class of mild ID at special school. Participants: The subjects were secondary level students of mild ID class from two special schools in Hong Kong. The sample sizes were 38, 19, 23 and 19 in trial 1, 2, 3 and 4 of the RCTs respectively. Simple randomization was done at student level in each trial. Intervention: Colored VM of optimal postures during screen-based device use was produced and verified with physiotherapist. Five to six daily sessions of (1) VM with physical prompts, (2) VM with verbal prompts, (3) VM with video prompts, verbal prompts and lower level of equivalence between instructional sets, and (4) VM with video prompts, verbal prompts and higher level of equivalence between sets were administered in different trials. Assessments: Demographic characteristics, subjects' neurodevelopmental disabilities and drug use, screen-based device use and the associated physical discomforts were assessed with baseline parent questionnaire. The cervical angle, thoracic angle and viewing distance of screen-based device use were assessed with photographic method at baseline, post-test and one-week follow-up in each trial. The photos were analyzed with on-screen protractor and assessment form for posture rating. Results: Overall, the VM with video prompts and verbal prompts was the most effective in training adolescents of mild ID class the posture of maintaining cervical angle of not smaller than 34.75° and supporting forearms and elbows during screen-based device use at post-test and one-week follow-up. Besides, there was a higher number of correct upper limb postures after VM with lower level of equivalence between instructional sets than the higher level of equivalence. Furthermore, there was generalization of skills between instructional sets with higher level of equivalence between tasks. Recommendations: The recommended dosage of the video-modeling included (1) two skill sets with low level of equivalence; (2) eight steps per day; (3) 7.5 seconds per step; (4) third-person point of view; (5) narrations per step; (6) VM on screen larger than 8", such as laptop; (7) VM twice per day; (8) VM for five to six days over one to three consecutive weeks; and (9) students' return demonstration with a maximum of two video prompts and verbal prompts per step per intervention day.