*2.2. Participants*

Participants who completed the online survey launched on 8 April until 21 April 2020 (during the government restriction measures) were considered eligible for the current study.

An overall total of 1928 of participants representing the country participated in the study by filling out the online survey. In order to minimize the effect of errors, a data cleaning process was adopted comprised of the following steps: exclusion of ineligible respondents including participants who did not complete the entire survey and of multiple submissions from the same participant; identification and management of meaningless data (e.g., duration expressed in hours, not in minutes; duration reported as weekly, not daily; duration reported as text, not as a number etc.).

Yet, after the cleaning process, a total of 1633 participants were included in the study.

#### *2.3. Internal Consistency of the Questionnaire*

The questionnaire used within the current study was built from IPAQ-SF. The questionnaire focused on two different moments, relating to before and during COVID-19 confinement restrictions. Specifically, it consisted of 31 items, assessing demographics (question 2 and 3), anthropometrics (question 4 and 5), PA before COVID-19 (question 7), employment status and residence during COVID-19 confinement (questions 8 to 13), the frequency and duration of vigorous-intensity PA before and during COVID-19 confinement (questions 14 to 17), the frequency and duration of moderate-intensity PA before and during COVID-19 confinement (questions 18 to 21), the frequency and duration of walking before and during COVID-19 confinement (questions 22 to 25), sedentary behaviour before and during COVID-19 confinement (question 26 and 27), and information related to PA during COVID-19 confinement. The introductory page of the questionnaire provided a concise description of the study and its main purposes, as well as the declarations of anonymity and confidentiality, and the personal data protection policy.

Since the questionnaire collected information of two different moments, to assess the validity of the obtained answers relating to past behaviour, question 7—"Before COVID-19 quarantine, how many days/week did you train regularly?" (with options ranging from 0 to 7 days per week)—was categorized into a dichotomous variable; according to the American College of Sports Medicine (ACSM) physical activity guidelines, people are considered sedentary if they train from 0 to 2 days per week, while they are considered physically active if they train from 3 to 7 days per week [33]. Therefore, a new variable, "physically active", with possible answers "Yes" or "No" was derived from the previous question.

Afterwards, to check if people where honest in their answers, a Mann–Whitney test was performed comparing the level of PA intensity (vigorous, moderate, walking) between sedentary and physically active individuals before the quarantine. If the respondents were honest in their answers, and the questionnaire was sensitive in detecting the amount of PA prior to the COVID-19 lockdown, sedentary people should also have reported less pre-confinement PA than active people. From the results reported in Table 1, sedentary respondents reported an amount of the three intensities of PA that is significantly lower than physically active respondents, indicating that they were honest in indicating their PA before quarantine.

**Table 1.** Internal consistency of the questionnaire: types of PA before COVID-19 quarantine declared by sedentary and physically active respondents (According to the ACSM Physical Activity Guidelines 2018).


VPA: vigorous physical activity; MPA: moderate physical activity.
