Several factors that potentially mediate swimming ability in children of Malmö were investigated in the present study. The strong influence of socio-demographic characteristics, on both individual and school level, was evident. Among the behavioural- and lifestyle factors, scores for “Activity”, “Outdoor time”, “Social relationships at home and on the free time”, and “Positivity about future” were found to affect the relationship between socioeconomic variables and children’s swimming ability. Including both sociodemographic and health- and wellbeing-related variables, appeared to increase the fit and the percentage of correctly classified estimates in our statistical model, compared to when only sociodemographic variables were included to the model. However, the difference between models was marginal, and striking associations between individual- and school-level sociodemographic condition and swimming ability remained even after the health- and wellbeing-related factors were taken into account.
Behavioural theories, such as the Social Cognitive Theory and the Ecological Model, emphasize that health behaviours, including various physical activity skills, are not only determined by physiological and genetic characteristics of an individual, but also by socio-environmental factors, such as knowledge, self-efficacy, motivation, interpersonal relationships and possible barriers (i.e. being able to get to the location of physical activity) [18,19,20]. Swimming ability has been previously reported to be strongly influenced by whether the children have a parent or friends that can swim if they have knowledge of water-safety and are encouraged to swim, and if they have swimming facilities nearby .
Our score of “Social relationships at home and on the free time”, consisting of responses to three statements (“I like my home”, “I have friends outside the school”, and “I have an adult to talk to about important things”) was a possible indicator of children’s perception of their home environment and support network. Feeling secure and having support from one’s family, has been previously reported to be fundamental to any kind of learning processes, as well as a promotor for physical activity [21,22,23,24,25]. Children who felt supported by their families and friends in the present study were thus both expected and found to have higher odds of being able to swim than children without a supportive background.
The score of “Activity” was based on the responses to four questionnaire statements: “I am actively participating in physical activity (PA) lessons at school”, “I bike or walk to school”, “I am doing sports and moving a lot in my spare time”, and “I have free time hobbies (e.g. scouts, music, fishing, reading, etc.)”. Since positive responses to all these statements reflect high motivation for physical activity, experience in learning new skills and a generally active lifestyle, it was not surprising to find a significant positive relationship between this score and children’s ability to swim. Similarly, positive responses to the statements included in the “outdoor time score” (“I’m outdoors during the breaks” and “I am often outdoors after school”), are likely to reflect an individual’s habit of regular physical activity and an active lifestyle . Self-efficacy – defined as “an individual’s belief in his/her capabilities to successfully execute necessary courses of action to satisfy situational demands” – has in previous literature been repeatedly identified as one of the most important factors to influence one’s will to exert and success in sports, and also, as a personal characteristic that may grow with regular physical activity [27,28,29,30]. Scoring high in “Activity” and “Outdoor time” may thus reflect and be associated to increased confidence in children about their motor capacity, which in its turn, is likely to increase an individual’s success in acquiring additional motor tasks, such as swimming ability .
Participants who selected “future is looking bright” (“Positivity about future”) choice had higher odds of being able to swim 200 m than those who did not agree with the statement. This finding was not surprising since expectations regarding personal abilities and future outcomes are central to the formation of human behaviour and strongly affect motivation to learn new skills [8, 31, 32]. A positive view of one’s future requires a positive appraisal of one’s current situation or a strong belief that things are going to become better. For being able to maintain such beliefs, however, a person needs both a sense of personal capability and a positive evaluation of the social environment providing the necessary support . Regular participation in physical activity has been reported to reinforce the feeling of internal capability in children and leads to an increase in optimism towards a successful life .
Swimming proficiency may affect several aspects of the human quality of life. Besides being a good all-round way to exercise, swimming is known to alleviate symptoms in children diagnosed with various chronic conditions [35,36,37]. Outdoor swimming (at both natural bodies of water and at public outdoor pools) is often a social activity undertaken by groups of friends or families. Being able to swim may encourage partaking in such activities and decrease the risk of feeling excluded and socially isolated. Furthermore, sufficient swimming skills may allow partaking in more advanced water-related activities, such as snorkelling and scuba diving, which have a potential to create amazing experiences for the person. In addition, good swimming skills increase the security regarding all kinds of activities performed in the natural environments of Sweden, since water is a rather common element in the Swedish nature .
One way to increase children’s interest in acquiring swimming skills could be by demonstrating the wider possibilities for activates that build on good swimming skills, also in other school subjects than the physical education (i.e. in the natural and social sciences). Since the intrinsic motivation (or “fun”), is the most influential factor in children’s desire to learn physical activity skills [9,10,11,12], being able to do “fun” activities in the future may increase the motivation to work harder on their swimming skills during the lessons. However, children from families with weak socioeconomic status may not see these “fun” activities as something that is realistically available to them in the near future. Thus, besides introducing the knowledge about activities that build on good swimming skills, it may be necessary to help these children (and their families) to find a way of becoming involved in such activities despite their limited resources. The present study demonstrated that social support, optimism for the future and an active lifestyle are important for children acquiring swimming skills. Schools, municipalities and youth organisations could help develop these factors by providing opportunities for “fun” nature-based activities, involving adult instructors that can give the support and encouragement that children may need.
Previous literature, as well as the present study, has highlighted that in Sweden swimming ability is generally lower among children from families with low socioeconomic status than among children from socioeconomically stronger families [4, 6, 38]. Furthermore, in several Swedish cities a location-based pattern has been observed, according to which a lower proportion of children are able to swim in municipalities with low socioeconomic status than in municipalities with high socioeconomic status [4, 6, 38]. Thus, efforts to increase swimming proficiency in Sweden should primarily aim to increase public equality and start with acquiring location-specific knowledge that may help design such equality-increasing initiatives. According to Heckman and Masterov 2007,  early interventions, which partially redress the effects of adverse milieus may reverse some of the harm of disadvantage and lead to a high economic return. Thus, investing resources in activities that increase children’s intrinsic motivation for an active life in socioeconomically weak areas may, not only benefit the children themselves, but also society at large by decrease future costs of, for example, legal system and health care.
The strengths of the present study were the availability of data on sociodemographic factors both at the individual and the school level and the relatively large sample included. In addition, the participation in the health examinations entered in the Pupil Health Database was high, which limited the risk of selection bias. However, using self-reported data and a cross-sectional study design were significant limitations of our study. Since no documented school grades concerning swimming ability were available, it is possible that some children may have over- or underestimated their swimming skills. However, it is reasonable to assume that the misclassification regarding over- and underestimation of one’s swimming ability was non-differential. There is also a potential for reverse causality since individuals who can swim, maybe generally more active which may result in increased wellbeing and positivity. A prospective cohort study, also including data on attitudes towards swimming as well as engagement and swimming ability among the parents, would elucidate drivers as well as barriers to swimming ability among children further.