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Chronic and acute effect of using the sit-stand desk as a strategy to reduce sedentary behaviour in administrative workers

Grant number: 19/25140-6
Support type:Scholarships in Brazil - Doctorate (Direct)
Effective date (Start): August 01, 2020
Effective date (End): August 31, 2024
Field of knowledge:Health Sciences - Physiotherapy and Occupational Therapy
Principal researcher:Ana Beatriz de Oliveira
Grantee:Luiz Augusto Brusaca de Azevedo Laureano da Silva
Home Institution: Centro de Ciências Biológicas e da Saúde (CCBS). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil


Office workers spend much of their working time in a sitting position. This sedentary behavior is considered an important risk factor for the musculoskeletal, physical and psychosocial system, in addition to increasing the risk of chronic diseases. Sit-stand table with an alert control system and multicomponent interventions have been proposed as a positive way to prevent these risk factors. However, these interventions did not show consistency in the medium and long term, when applied alone. In addition, it is known that this type of intervention can favourably alter variables of the cardiovascular system, however, little is known about the cardiovascular autonomic control of individuals who use the sit-stand table. To answer these limitations, an intervention and a laboratory study are proposed in this project. Study I will investigate whether the use of the sit-stand table associated with an alert control system with predefined time to remain in the sitting (40 min.) and standing (20 min.) position in conjunction with a personalized approach for six months can promote changes in the general level of physical activity and positively affect the musculoskeletal, physical and psychosocial health of office workers with overweight/obesity. Forty-five workers will be part of this study, divided into three groups: intervention (GI; sit-stand table, control system and personalized approach), comparison (GIC; sit-stand table and control system) and control (GC; traditional table). The assessment of the level of physical activity will be performed using accelerometers and the assessment of musculoskeletal symptoms, physical and psychosocial factors using questionnaires. The evaluations will take place one week before the intervention, in the third and sixth months. The accelerometer data will be processed in specific software and analysed with Compositional Data Analysis (CoDa) that will allow to perform a descriptive statistic of the data, as well as the application of the mixed model variance test (ANOVA). Additionally, an isotemporal substitution model calculated with the data from the first evaluation will be applied. The questionnaire data will be analysed using a Multilevel Mixed Model. The objective of Study II will be to evaluate and characterize how cardiovascular autonomic control (Heart Rate Variability [HRV], Blood Pressure Variability [BPV] and Baroreflex Sensitivity [BRS]) occurs in individuals with normal weight who use the sit-stand table compared to sitting position. It will be a controlled crossover laboratory study, composed of forty-nine individuals with normal weight. Volunteers will experience two conditions lasting 3 hours each: (a) sitting (table in standard position); (b) alternating between sitting and standing position (40/20 min.). The sequence of conditions will be randomized, and there will be a wash-out period of 2 to 10 days between them. Before and after each experimental condition, the active postural maneuverer and maneuverer to Accentuate respiratory Sinus Arrhythmia (ASR) will be performed, where data from electrocardiogram, respiratory movements and blood pressure will be recorded. Stable sequences of 256 points will be chosen in the time series of the cardiac period, Systolic Blood Pressure (SBP) and respiratory movement. From these time series, HRV, SBPV and BRS indices will be calculated in the domain of time and frequency. And the ASR indexes in the time domain. Data will be analysed using mixed model ANOVA. The characterization of the acute effect of using the sit-stand table on cardiac autonomic control, and the chronic effect of longitudinal intervention on the general level of physical activity and other exposure variables may assist health professionals in choosing this tool as an intervention in office workers with or without overweight/Obesity. (AU)