Post-COVID-19 Status and Its Physical, Nutritional, Psychological, and Social Effects in Working-Age Adults—A Prospective Questionnaire Study

Background: The main objective of this study was to evaluate the evolution of physical and daily routine, dietary habits, and mental and social health in individuals with recent COVID-19 infection. Methods: A qualitative prospective cross-sectional study was conducted from 01 October 2021 to 01 March 2022, which included 80 working-age adults from the territory of Central Serbia who had PCR-confirmed SARS-CoV-2 infection in the previous six months. Two structured pre-coded closed-ended questionnaires were submitted to the participants: a questionnaire about post-COVID-19 status (pCOVq) and a shortened version of the World Health Organization’s Quality of Life Scale (WHOQOL-BREF). Results: The presence of the COVID-19 disease in the previous period of 6 months among the working-age participants significantly affected the duration of aerobic, anaerobic, and high-intensity physical activities, but also the possibility of performing certain activities such as walking, which represents basic aerobic activity and a measure of general health among middle-aged participants. In the majority of cases (78%), in the post-COVID-19 period, participants indicated a decline in educational and productive activities. Conclusion: Post-COVID status in working-aged participants consists of reduced physical activity, lower quality of life, and similar nutritional habits. Health policies should be more focused on these findings.


Introduction
After the December outbreak of COVID-19 in Wuhan, China, the infection spread rapidly to other parts of the world, and the increasing number of cases suggests that the disease continues to spread steadily [1]. Initially, it was thought that people who had been to the seafood market or consumed food prepared with infected animals had been infected with COVID-19. However, it was later found that a number of people who had not traveled to the seafood market were also infected, i.e., tested positive for COVID-19 [2,3]. This showed that human-to-human transmission of the virus was possible, which was later confirmed in many countries around the world [1][2][3][4]. Thanks to the interventions and control measures taken by governments around the world, the number of newly confirmed cases is decreasing worldwide [5]. Although all important measures are being implemented, the risk of transmission has not yet been eliminated, and the epidemic remains a major challenge for clinicians. A large proportion of patients have a mild or moderate course in the cities of central Serbia, and a positive answer to the question from the first part of the questionnaire (voluntary consent to the study). Exclusion criteria were age less than 18 years and more than 50 years old, place of residence in other countries/regions of the world, as well as an incompletely completed survey and previous hospital treatment regarding COVID-19 disease.

Instruments
Two structured pre-coded closed-ended questionnaires were submitted to the participants: a questionnaire about post-COVID-19 status (pCOVq) and a shortened version of the World Health Organization's Quality of Life Scale (WHOQOL-BREF).

A Questionnaire about the Post-COVID-19 Status (pCOVq)
The questionnaire on the post-COVID-19 status of adults in the territory of the municipality of Kragujevac is a standardized tool constructed by the author Kang-Hyun Park and associated and validated on the population of adult respondents during 2020 [16]. The pCOVq is an anonymous questionnaire that consists of 26 questions; each question has up to 6 sub-questions related to the period before and after the infection, and the time allotted for filling it is less than 60 min. The questionnaire consisted of domains, each of which separately analyzed one aspect of life related to the patient, i.e., the respondent (1) physical activity, (2) participation in activities, and (3) nutrition. In previous studies, the pCOVq questionnaire showed high internal reliability, with a Cronbach alpha of 0.83. The intraclass correlation coefficient was 0.97 for the total score of the questionnaire in terms of test-retest reliability [16].

Physical Activity as a Lifestyle Indicator in Post-COVID Period
A total of six physical activity items were assessed using a five-point Likert scale to measure respondents' frequency of participation in six different physical activities and their satisfaction with participating in these physical activities. The six physical activities included aerobic physical activity; anaerobic physical activity; low-intensity physical activity equivalent to 2-2.9 metabolic equivalents of the task (MET), including gardening, house cleaning, etc.; moderate-intensity physical activity equivalent to 3-5.9 METs, including swimming, doubles tennis, etc.; high-intensity physical activity equivalent to 6-9.9 MET, such as running, climbing, etc.; and walking exercises. According to the American College of Sports Medicine (ACSM), physical activity can be divided into three types, based on intensity. To assess the impact of the COVID-19 pandemic on physical activity, questions were asked about the frequency and satisfaction of participating in physical activity weekly before and after the onset of COVID-19. The higher the score, the higher the level of participation and satisfaction with physical activity.

Daily Activity as a Lifestyle Indicator in POSt-COVID Period
Six items about the daily activity were also assessed using a five-point Likert scale to measure the frequency of and satisfaction with the variety of present daily activities, such as activities of daily living (ADL), leisure, social activities, work, education, and sleep during the week before and after COVID-19. A higher score indicates more frequent participation in various activities as well as greater satisfaction with participation in activities.

Nutrition as a Lifestyle Indicator in Post-COVID Period
Finally, nine items on diet were assessed using a five-point Likert scale to assess diet in the week before and after COVID-19 and to measure participants' nutritional status. The amounts of carbohydrates, proteins, fats, vitamins, minerals, water, and alcohol that participants consumed, as well as the frequency of drinking and smoking, were measured. For example, participants were asked, "Before the COVID-19 pandemic, how often did you consume carbohydrate-rich foods such as rice, bread, and flour in the last week?" Participants responded to these questions by selecting one of the five-point Likert scale options: (1) never, (2) 1-2 times a week, (3) 3-4 times a week, (4) 5-6 times a week, and (5) every day. A higher score indicates a higher consumption of each type of food.

A Shortened Version of the World Health Organization's Quality of Life Scale (WHOQOL-BREF)
A shortened version of the World Health Organization's Quality of Life Scale (WHOQOL-BREF) was used to assess quality of life [17,18]. It contains 26 items rated on a five-point Likert scale and measures four domains: physical, psychological, social and environmental. Raw domain scores were converted to a scale ranging from 0 to 100 to facilitate comparison with other instruments, with higher scores indicating higher quality of life. Cronbach's alpha was 0.91 and 0.94 before and after COVID-19, respectively. Each question has 7 possible answers scored on a Likert scale from 0 to 6, with 0 corresponding to the feeling that it "never" happens and 6 indicating that it happens "every day". Quality of life was assessed only six months after COVID-19, since we could not predict who will be infected [17,18].

Data Management and Statistical Analysis
This cross-sectional prospective study included the participants who satisfied the inclusion criteria mentioned before. According to the results of the previous study, the sample size was arrived at using the margin of error approach as seen in the equation below: n = Z2P(1−P)/d2. The sample size was set at 80 participants. In the evaluation of the quality of life and clinical status, 4 (5%) participants were excluded because of an incompletely filled survey, which is permissible exclusion. Statistical analyses were performed in the SPSS program version 26 using descriptive and statistical analytical tests. Results are presented as frequencies in percent (%) or as arithmetic means and standard deviations (X; SD). A Chi-square test was used to estimate the statistical differences in the distributions of categorical variables. The statistical threshold was set at the level of 0.05. Table 1 shows the basic demographic characteristics of the study population. Most participants were female, with a mean age of 30.64 ± 1.54 years. In addition, most participants were under 30 years of age, single, employed, and living in a medium-sized city ( Table 1).

Clinical Status of the Working-Age Study Population
In the form of Table 2, the clinical symptoms among the study population during the period after COVID-19 are shown. During COVID-19, most patients had many current symptoms such as sleep problems, bowel and bladder dysfunction, and respiratory problems. Some of the participants had joint movement restrictions, odor disturbances, circulatory problems, and pain. Interestingly, in the period after COVID, many of these complaints were still present, such as limitations in the sense of smell (17.1%) and taste (15.8%) and breathing problems (14.5%), and most participants had persistent increased fatigue (23.7%). Further, there was a not insignificant number of participants with other persistent symptoms six months after COVID-19 (Table 2).

Changes in Different Types and Intensities of Physical Activity in the Working-Age Study Population after SARS-CoV-2 Infection
In this study, we examined the effects of SARS-CoV-2 infection on the different types and intensities of physical activity six months after the onset of the disease (Table 3). We asked participants about the frequency of aerobic, anaerobic, daily, light, and highintensity physical activity. Interestingly, both aerobic and anaerobic activity changed, and a greater number of participants reduced these physical activities in the period after COVID. Similarly, the number of participants who engaged in high-intensity physical activity decreased, whereas the consumption of low-and moderate-intensity physical activity did not decrease (Table 3). Table 3. Differences in the frequency of aerobic and anaerobic physical activity, as well as in low-, middle-, and high-intensity activity before and six months after COVID-19. Results are presented as frequency in percent from total number of participants [%]. Statistical significance was obtained using Chi-square test (X2) as follows: a = statistically significantly higher number of participants compared to activity before and after COVID-19, b = statistically significantly lower number of participants compared to activity before and after COVID-19.

Type of Activity Aerobic Activity
Anaerobic Activity  In terms of duration, there was an increase in the number of participants who did not engage in physical activity during the period after COVID. The opportunity to engage in physical activity after SARS-CoV-2 infection was also reduced, especially for aerobic and high-intensity activities (Table 3).
Regarding the other activities, Table 4 shows the statistical differences in the period before and six months after COVID-19 in the study population. Statistically significant reductions were observed in the frequency and duration of daily and social activities and in the duration of productive and educational activities. As expected, social activities were most reduced in our working-age population (Table 4). Table 4. Participation in different activities in the period before and six months after COVID-19 among the study population. Statistical significance was obtained using the Chi-square test (X 2 ). Asterisks (*) represent the statistically significant difference in selected characteristic of activity before and six months after COVID-19, and the double asterisk (**) represents high significance (<0.001).

Activity and Its Characteristics (n = 80) p Values
Daily activity

Nutrition Habits in the Post-COVID Period among Study Population
From Figure 1 and Table 5, we can see that dietary habits changed significantly in the period after COVID, although most of the changes were not statistically significant. Interestingly, the frequency of water consumption changed in the period after COVID, with a large number of participants consuming water five to six times per week or daily ( Figure 1; Table 5). In general, the National Academies of Sciences, Engineering, and Medicine suggests that each day, women drink a total of about 2.7 L (L) or 11 cups of fluid and men consume about 3.7 L (16 cups). Every additional cup is recognized as additional water consumption (Figure 1; Table 5).  Table 6 shows the frequency of responses related to self-satisfaction and quality of life. Most participants were satisfied in many ways, but there are still a large number of participants who were generally not satisfied. All questions refer to post-infection symptoms (COVID), so we found that a statistically significant number of participants were only dissatisfied to very dissatisfied with life, health status, daily activities, and personal relationships, which can be considered as decreased satisfaction (Table 6).

Discussion
The primary objective of this study was to assess the evolution of physical and daily routine, as well as mental and social health in individuals with recent COVID-19 infection over a six-month period after infection and the factors associated with (un)favorable evolution. Secondary objectives were to assess general health and vital energy in workingage individuals, social functioning, and dietary behaviors in the post-COVID period.
For the first time, a study addresses the assessment of the impact of acute infection on the range of other vital activities in young people of working age [19,20]. A variety of questionnaires were used to assess behavior, satisfaction, and objective interference with physical activities. The identification of risk factors for prolonged disease progression is necessary, and early identification and monitoring of patients at increased risk for developing post-syndromal COVID must be a priority.
It has been proven that more than 60% of patients who had COVID-19 have many persistent symptoms and syndromes in the period after COVID [21]. This information could be important not only for healthcare professionals, but also for the economy and people in general, because protracted illness is a global problem, not just an individual disability.
Post-COVID syndrome is a serious condition that includes a variety of new, recurrent, or persistent symptoms that people usually experience at least four weeks after a positive SARS-CoV-2 test [22]. In some cases, symptoms persist for more than 3 months when this syndrome begins as a chronic form of the disease [23].
The results of our study show that there is a statistically significant difference in certain segments before and after infection. Regarding aerobic and anaerobic exercise, the number of subjects who performed these activities decreased significantly after infection. A statistically significant difference was found in the performance of low-and high-intensity physical activities before and after infection.
The duration of low-intensity physical activity decreased sharply, and for highintensity physical activity, the duration, frequency, and opportunity to engage in it decreased after infection (Tables 2-4). There was also a difference in the duration and opportunity to walk before and after infection, with a decrease in the length of walking and an increase in the number of respondents who reported walking as much as possible. Responses on activities of daily living and leisure showed a statistically significant difference in the performance of these activities before and after infection. The frequency with which daily activities were performed decreased, as did the duration of leisure activities. There was a difference in the frequency with which social and educational activities were performed and in the opportunity to perform them ( Table 4). The questions about productive and social activities showed a difference in the duration of these activities, with a significant decrease in the number of respondents who engaged in sports activities for more than one hour. Regarding dietary habits before and after infection in terms of carbohydrates, proteins, vitamins, minerals, and fatty foods, statistical analysis showed that there was no statistically significant difference in the consumption of these nutrients ( Figure 1, Table 4).
Regular physical activity is one of the most effective ways to prevent morbidity and early death. The World Health Organization recommends at least 150 min of moderate physical activity per week [24,25]. Individual factors such as gender, age, and health status influence the physical activity that people engage in. During the COVID-19 pandemic, a large proportion of the population remained confined to their homes [24,25]. To prevent physical inactivity, experts recommended getting up, walking around the house, and exercising online. During the pandemic, there were negative effects on physical activity intensity and an increase in the consumption of less healthy foods, as well as an increase in sedentary lifestyle. A decrease in physical activity was also observed in college students, but an increase in anxiety was also observed in individuals aged 18-34 years [26,27].
A study by Bakhsh et al. [24] was conducted with the aim of determining whether the dietary and physical activity patterns of the adult Saudi population changed during the COVID-19 quarantine. The methodology of the study was based on an electronic questionnaire that assessed changes in body weight, eating habits, and physical activity among the adult population of Saudi Arabia (n = 2255) during the COVID-19 quarantine and was disseminated through social networks during the period between June and July 2020. The results of this study showed that over 45% of participants reported consuming larger amounts of food and snacks, which led to weight gain in approximately 28% of subjects. Feeling bored and empty, as well as the availability of time to prepare meals, were the main reasons for changing eating habits. Honey and vitamin C were the most commonly consumed foods to boost immunity. COVID-19 negatively affected physical activity in 52% of respondents, which was associated with a significant increase in body weight (p < 0.001) [21]. The aforementioned study examined the changes in dietary habits of the adult population of Saudi Arabia from the aspect of respondents' weight gain, whereas our study examined the difference in micro-and macronutrient intake before and after Corona virus infection. However, our results did not show that there was a statistically significant difference in the intake of macro-and micronutrients analyzed in our questionnaire.
A study by the author Ferreira Rodrigues et al. [25] was conducted with the aim of showing changes in food consumption and food product choices during the pandemic COVID-19 in the Brazilian population. Consumer perceptions of food safety and marketing issues were also studied. An online survey was conducted, and the data were analyzed using descriptive analysis. The results of the study show that the COVID-19 pandemic has affected the consumption and purchase of food. Respondents reported eating and buying larger quantities of food, indicating an increased tendency to eat less healthy food, especially among women. On the other hand, homemade preparations and fresh foods were preferred [25].
Theis et al.'s [26] cross-sectional study was conducted to examine the impact of COVD-19 pandemic-related limitations on physical activity and mental health in children and adolescents. The electronic survey was conducted from June to July 2020. Respondents reported negative effects of isolation, with 61% reporting a decline in physical activity levels and over 90% reporting a negative impact on mental health, including poorer behavior, mood, fitness, and regression in social activities and learning [26].
Since most studies on COVID-19 virus infection have focused on transmission, morbidity, and mortality, a study by Poudel was conducted with the aim of assessing the impact of the virus on health-related quality of life (HRQoL) [27]. The results of this study suggest that a greater impact on HRQoL was achieved in acute infections, women, elderly patients, patients with more severe disease, and patients from low-income countries [27].
COVID-19 can lead to many permanent symptoms such as fatigue, shortness of breath, and decreased ability to perform activities of daily living [28,29]. Clearly, recovery or rehabilitation is necessary to return to a normal state after infection. Pulmonary rehabilitation is an evidence-based intervention that addresses many of the symptoms experienced by long-term infected individuals of COVID-19 (defined as symptoms that persist ≥ 3 months after infection), such as shortness of breath, low energy, impaired ability to perform daily tasks, sleep disturbances, and lower self-confidence. At the molecular level, fatigue and fatigue after COVID-19 could be related to persistent inflammation [28][29][30][31]. Pandemic lockdowns have been thought to lead to inactivity and an increase in sedentary behavior, and all necessary measures should be taken to prevent these effects. During isolation, people change their lifestyle habits, increasing the time spent sitting and decreasing the time spent exercising [29][30][31][32][33].
In a study conducted in Spain [34] related to students, it was confirmed that the time spent sitting increased, but surprisingly, the time spent in physical activity also increased, as well as the number of days participants were active. It was found that students who ate a Mediterranean diet exercised more, whereas there was little change in their physical activity behavior. This only goes to show that those who lead a healthy lifestyle also pay attention to their diet and exercise and maintain their habits regardless of the environment. Although the results are positive in terms of physical activity, it should be noted that this population could experience health problems in the future due to the increase in sitting. The most likely reason for the increase in physical activity among young people is that they have realized that their time spent sitting has increased (not going to school, shopping, etc.) and have compensated for this by exercising [34,35]. Another reason could be that students are primarily studying in the health sciences, so they were more inclined to exercise during the pandemic than students in other majors, such as engineering [35].
The limitation of this study is the lack of objective methods of measurement, such as laboratory tests before and after COVID-19, but because infection as well as prolongation of symptoms could not be predicted, this limitation must be justified. Further, the measurement of the costs in case of work loss of these individuals affected by the COVID syndrome could be of importance and interesting to evaluate.

Conclusions
The presence of the disease of COVID-19 in the previous 6 months in working-age participants significantly affected the duration of aerobic, anaerobic, and high-intensity physical activities, but also the ability to perform certain activities such as walking, which is a basic aerobic activity and a measure of overall health in middle-aged participants. In the majority of cases (78%), participants reported a decrease in educational and productive activities after COVID-19 compared with the period before COVID-19. Statistical analysis of dietary habits, such as consumption of carbohydrates, proteins, vitamins, minerals, and fatty foods, showed that there was no statistically significant difference in the consumption of these nutrients before and after infection. Health policies should be further guided by these findings.