To assess sedentary behavior, participants (parents and children) will answer the Sedentary Behavior Questionnaire (SBQ). It includes the domains of sedentary behavior (watching TV, playing video games and computer, sitting listening to music, sitting talking on the phone, working on the computer or bureaucratic tasks {e.g. answering emails}, playing a musical instrument, doing construction work art or crafts, sitting in a car, bus, or train) during the week and on weekends.

To assess CS with direct measurement, participants will use the Actigraph GT3X (ActiGraph, LLC, Pensacola, FL, USA). The accelerometer data will be filtered, digitized and adjusted to a frequency of 30Hz with an interval (epoch) of 60 seconds. The accelerometer will be analyzed by ActiLife 6 software (ActiGraph, LLC, Pensacola, FL, USA). Data will be considered complete if the participant wears the accelerometer for at least 10 hours per day for 4 days. It will be used to characterize sedentary behavior when measuring <100 counts/min (< 1.5 METs). The outcome of interest will be the time spent in sedentary activity, the number of minutes per day, which will be converted into hours for the analyses, according to the cutoff point of Matthews et al. (2008).

Blood pressure will be assessed using an Omron automatic blood pressure measuring device (Model HEM-742, Japan).

Height will be measured standing up, with a fixed stadiometer and with individuals barefoot, will be displayed in centimeters.

Body mass was measured using a digital scale, on which the individuals were barefoot and wearing light clothing, expressed in kilograms.

Based on body mass and height measurements, the body mass index (BMI) will be calculated by dividing the participant's weight by their height squared, expressed in kilograms per meter squared.

Abdominal obesity will be determined by waist circumference, using an inextensible metallic tape, will be displayed in centimeters.

The heart rate variability will be collected by means of the POLAR V800

The dual-energy X-ray absorptiometry technique (DEXA, Lunar DPX-NT; General Electric Healthcare, Little Chalfont, Buckinghamshire, United Kingdom) will be used to measure lean body mass in kilograms (kg) and bone mineral density (BMD ) in grams per square centimeter (g/cm2) of arms, legs, trunk, pelvis, spine and entire body. The equipment's own software will be used (GE Medical System Lunar, version 4.7). The analysis procedures were reported in a previous study by Saraiva et al. (2021). The machine's accuracy in terms of coefficient of variation was tested in a pilot study with 30 volunteers not involved in this study and resulted in an error of less than 1%. Both parents and children will undergo this assessment.

To assess HRQoL, the Medical Outcomes Study SF-36-Item Short Form Health Survey (SF-36) instrument was used. The SF-36 is made up of 36 items that cover eight domains regarding HRQoL: functional capacity, physical limitations, body pain, general perception of health, vitality, social aspects, emotional limitations, mental health and current perception of health in comparison a year ago. This instrument presents a final score from 0 to 100, where 0 represents the worst score and 100 represents the best score in relation to HRQoL (WARE et al., 1992).

Will be assessed using the KIDSCREEN-52 questionnaire. This instrument was developed in European countries to assess the health-related quality of life of children and adolescents (RAVENS-SIEBERER, et al., 2001). T

The Hospital Anxiety and Depression Scale (HADS) will be used, which contains 14 multiple-choice questions, seven of which assess symptoms of anxiety and seven of depression. Each item can be scored from 0 to 3 and the maximum score is 21, for both anxiety and depression (ZIGMOND & SNAITH, 1983). This scale is also validated for use with children and young people (WHITE et al., 1999).

This aspect will be assessed in the parents of adolescents participating in the study using the Brazilian version of the Perceived Stress Scale (COHEN et al., 1983), validated by Siqueira Reis et al. (2010) which consists of 14 items about the frequency of feelings and thoughts related to events and situations that occurred in the last month, with seven items being negative (1, 2, 3, 8, 11, 12 and 14) and seven items being positive (4, 5, 6, 7, 9, 10, and 13). Each item is answered on a five-point Likert frequency scale, with 0=never and 4=very often. The stress score is constructed by adding the values answered in each of the items, with positive items being on an inverse scale (0=very often and 4=never). The total score varies from 0 to 56 points and the higher the score, the higher the stress level.

The presence of musculoskeletal symptoms will be assessed using a questionnaire developed by Kuorinka et al. (1987) and validated for its use in the Brazilian population (PINHEIRO et al., 2002). This instrument assesses some musculoskeletal symptoms such as the presence of pain, tingling or numbness in different parts of the body (neck, shoulder, upper back, elbows, wrists/hands, lower back, hip/thigh, knees and ankles/feet ). It is noteworthy that this instrument is also validated for use with children and adolescents (LEGAULT et al., 2014). The intensity of pain and how long the participant has felt pain will also be assessed on a scale of zero to ten.

Will be assessed using the Mini-sleep Questionnaire (ZOMER et al. 2005), validated for the Portuguese language (FALAVIGNA et al. 2011), which consists of 10 questions with seven possible answers. (never= 1, very rarely= 2, rarely= 3, sometimes= 4, often= 5, very often= 6 and always= 7) and provides a dimensionless score (higher score, worse sleep quality). The final score generated by the instrument can be classified as: good sleep (score between 10 and 24 points), slightly altered sleep (score between 25 and 27 points), moderately altered sleep (score between 28 and 30 points) and very altered sleep ( score above 30 points). Subjects who have a score equal to or greater than 28 points will be classified as having altered sleep.

Sleep latency will be investigated using the Pittsburg questionnaire (BUYSSE et al., 1989).

Eating habits will be verified through the frequency of weekly consumption of different foods based on the work of Block et al. (2000). The consumption of foods such as vegetables, fruits, cereals, dairy products, fried foods, sodium and sugary drinks (soft drinks), as well as stimulant (energy) and caffeinated drinks will be analyzed.

Alcohol consumption will be assessed by the weekly frequency of alcohol intake and the number of doses consumed. Adults who reported drinking alcoholic beverages with a frequency equal to or greater than 1-2 days a week with an intake of 1-2 drinks per day will be considered to have high alcohol consumption (each dose will correspond to 250 ml for beer and 40 ml for soft drinks distilled).

In determining the economic condition of families, the "Brazilian Economic Classification Criteria" established in 2011 by the Brazilian Association of Business and Research (ABEP) will be used, according to a database from a survey carried out in 2009. by the Brazilian Institute of Public Opinion and Statistics (ABEP, 2009).

As the coronavirus may exert or have exerted influences on some of the variables investigated in this study (for example: mental health, cardiac autonomic modulation), participants will be asked: Have you been diagnosed with Covid-19? If so, how did your clinical condition evolve? Asymptomatic, mild symptoms, moderate symptoms (I needed medication), severe symptoms (I needed hospitalization), very serious symptoms (I needed intensive therapy).