Perceived Impact of Outdoor Swimming on Health: Web-Based Survey

Background: Outdoor swimming in lakes, lidos (outdoor pools), rivers, and the sea has grown in popularity in many countries, including the United Kingdom. Many anecdotal accounts indicate improvements in medical conditions, which are considered a consequence of outdoor swimming. Objective: The aim of this study is to better understand outdoor swimmers' perceptions of their health and the extent to which participation impacted their existing self-reported symptoms. Methods: A survey was conducted to investigate outdoor swimming behaviors and reports of any diagnosed medical conditions. Medical conditions were coded into categories, and descriptive statistics were generated regarding the outdoor swimmers' behaviors and the effect that outdoor swimming had on their medical symptoms if any. The medical categories were clustered into five larger categories based on their prevalence in the current sample: mental health; musculoskeletal and injury; neurological; cardiovascular and blood disease; and other, which comprises inflammatory, immune, endocrine, and respiratory conditions. Results: In total, 722 outdoor swimmers responded, of whom 498 (68.9%) were female. The probability of outdoor swimming having some positive impact on health across all medical categories was 3.57 times higher compared with no impact (B=1.28, 95% CI 0.63-1.91; P<.001), 44.32 times higher for the mental health category (B=3.79, 95% CI 2.28-5.30; P<.001), 5.25 times higher for musculoskeletal and injury category (B=1.66, 95% CI 0.52-2.79; P=.004), and 4.02 times higher for the other category (B=1.39, 95% CI 0.27-2.51; P=.02). Overall, outdoor swimming was associated with perceived reductions in symptoms of poor mental health (chi(2)(2)=25.1; P<.001), musculoskeletal and injury (chi(2)(2)=8.2; P=.04), cardiovascular and blood (chi(2)(2)=14.7; P=.006), and other conditions (chi(2)(2)=18.2; P<.001). Conclusions: Physical activity in the form of outdoor swimming is perceived to have positive impacts on health and is associated with perceived symptom reductions in mental health, musculoskeletal and injury, and cardiovascular and blood conditions. This study cannot provide causal relationships or provide mechanistic insights. However, it does provide a starting point for more targeted prospective intervention research into individual conditions or categories of conditions to establish the impact in those who choose to start outdoor swimming.