## 2 Materials and Methods  
Parents/guardians of children and adolescents aged 3-17 years from Spain and Brazil were invited to respond to an online survey that required around 15 min to be completed. Informed consent was required before completing the survey. A snowball sampling strategy was used to recruit participants. Data collection lasted 15 days in both countries (in Spain from 29 March 2020 and in Brazil from 14 April 2020). The initial sample was composed of 1263 respondents; however, 143 participants were discarded because they were out of the age range. Additionally, 21 participants presented missing values and were removed. The final analysis included data from 1099 respondents. The Ethical Committee of the Universidade Tecnologica do Parana (UTFPR; CAAE: 32023220.8.0000.5547; approval number: 4.275.232) and the Universidad Catolica de Murcia (UCAM; code: CE112001) approved the study. Respondents were requested to complete the survey if they had experienced COVID-19-related restrictions during the previous week (lockdown). The first section of the survey gathered general data on the restrictions. Parents' nationality and socioeconomic status (assessed with the Family Affluence Scale--FAS-III) [14], educational level, age, and sex of their children was requested. Anthropometric data (height in centimetres and weight in kilograms) were reported by parents for their children. The WHO criteria were used to analyse the z-score for BMI and the classification of overweight/obesity [15; 16]. The following question was used to assess PA: \"_During the COVID-19 lockdown, how many days was your child physically active for a total of at least 60 min?_\". This question has been reported to have good reliability and validity for PA assessment [17]. Respondents could provide answers ranging from 0 to 7 days per week, and the different options were presented in 1-day increments. Compliance with the PA recommendations was defined as 60 min of moderate-to-vigorous PA per day, 7 days per week. Respondents were asked to indicate the time that their child spent in different sedentary screen-based pursuits to assess screen time. The following questions were asked in relation to the COVID-19 pandemic [18]: (a) _\"How many hours a day, during the COVID-19 lockdown, does your child spend watching TV, videos (including YouTube or similar services), DVDs, and other entertainment on a screen?\"_; (b) _\"How many hours a day, during the COVID-19 lockdown, does your child spend playing games on a computer, games console, tablet, smartphone or other electronic device (not including moving or fitness games)?\"_; and (c) _\"How many hours a day, during the COVID-19 lockdown, does your child usually spend using electronic devices such as computers, tablets or smartphones for other purposes (e.g., homework, emailing, tweeting, Facebook, chatting, surfing the internet)?\"_. The three answers were summed considering a week distribution of 5 weekdays and 2 weekend days. Screen time was classified as follows: pre-schoolers (\"not meeting ST guidelines\": >1 h/d; \"meeting the screen time guidelines\": <1 h/d); and children/adolescents (\"not meeting ST guidelines\": >2 h/d; \"meeting the ST guidelines\": <2 h/d). The WHO guideline recommendations for ST children under 5 years old were used to categorise the variable [19], and as the WHO guidelines do not include specific cut-off points for children and adolescents, Canadian guidelines for ST were considered [3]. Time spent sleeping during the COVID-19 pandemic was assessed with the following question: _\"What time does your child usually go to bed?\"_ and _\"What time does your child usually get up?\"_. Both questions were asked differentiating weekdays and weekend days [20]. The following equation was used to calculate the average daily sleep duration: ((average nocturnal sleep duration on weekdays \(\times\) 5) + (average nocturnal sleep duration on weekends \(\times\) 2))/7.