Health, Fitness, and Safety Knowledge as Determinants of Adverse Events in Recreational Divers in Poland

Primary objective: to assess health status, physical fitness, and safety/training knowledge in relation to the occurrence of diving-related adverse events among recreational divers in Poland.

Specific objectives: (1) estimate VO2max from the University of Houston Non-Exercise Test; (2) assess knowledge of decompression sickness, barotrauma, and safe-diving rules at basic, advanced, and emergency-medical levels; (3) determine the frequency of barotrauma and decompression sickness symptoms (clinically confirmed versus presumed); (4) identify risky behaviours (smoking, alcohol use, diving under the influence, and diving beyond certification); (5) assess associations between training level, physical activity, and health and the occurrence of adverse events using multivariable logistic regression.

Hypotheses: H1 - higher certification (Advanced Open Water Diver and above) is associated with better knowledge of diving-related health hazards; H2 - lower estimated VO2max is associated with a higher frequency of adverse events; H3 - risky behaviours are more frequent among lower-certified divers; H4 (exploratory) - decompression sickness risk factors identified in the DAN DSL 2024 dataset are present in the Polish recreational diving population.

Design: cross-sectional, observational, non-interventional study conducted as an anonymous online survey. No clinical procedures, biological sampling, or modification of medical management are involved.

Population and sampling: adults (18 years or older) residing in Poland who completed at least one dive in the past 24 months, recruited online (convenience sampling) via diving organizations, dive centers, and themed social-media communities.

Sample size: target analytic n = 384, derived by triangulation of three methods (proportion estimation n = 323; two-proportion comparison n = 304; logistic-regression events-per-variable rule n = 234), with the binding value (323) plus a 15% non-response buffer.

Data collection and privacy: anonymous online questionnaire hosted on Medical University of Bialystok infrastructure (REDCap); no identifying data and no IP address are stored; processing is GDPR-compliant; data are retained on secured university storage for 5 years and used only for aggregate scientific analysis.

• Anonymous online questionnaire (Other): Anonymous online questionnaire completed once by each participant (about 12 to 18 minutes). It captures demographic data, diving exposure and certification level, chronic health conditions, risky behaviours, estimated VO2max (University of Houston Non-Exercise Test), and a diving-safety knowledge test. No clinical procedures or biological sampling are involved; this is the observational data-collection instrument for the cohort.

Primary outcomes

• Prevalence of diving-related adverse events [At enrollment (Day 1; single cross-sectional assessment)]: Proportion of divers reporting at least one diving-related adverse event (barotrauma symptoms, decompression sickness symptoms, or other post-dive health problems) occurring at any time during the participant's diving history up to enrollment (lifetime recall). Reported as a percentage with 95% confidence interval.

Secondary outcomes

• Estimated VO2max (University of Houston Non-Exercise Test) [At enrollment (Day 1; single cross-sectional assessment)]: Estimated maximal oxygen uptake (mL/kg/min) calculated from the University of Houston Non-Exercise Test (physical activity rating, age, BMI, and sex), summarized as mean with standard deviation and as median with quartiles, stratified by sex and age.
• Diving safety knowledge score [At enrollment (Day 1; single cross-sectional assessment)]: Percentage of correct answers on the diving-hazard knowledge test (decompression sickness, barotrauma, and safe-diving rules), reported overall and at three difficulty levels: basic, advanced, and emergency-medical.
• Frequency of risky behaviours [At enrollment (Day 1; single cross-sectional assessment)]: Proportion of divers reporting risky behaviours: tobacco use, alcohol use before diving, diving under the influence of alcohol or other substances, and diving beyond their certification level.
• Adjusted odds ratios for diving-related adverse events [At enrollment (Day 1; single cross-sectional assessment)]: Adjusted odds ratios (with 95% confidence intervals) for the occurrence of at least one diving-related adverse event, estimated by multivariable logistic regression, for certification level, estimated VO2max, BMI, and selected risk factors from the DAN DSL 2024 dataset (e.g., sex, thermal comfort, pre-dive physical activity).

Sex: All, ages: 18 Years to any, accepts healthy volunteers

Inclusion Criteria:

* Age 18 years or older
* At least one dive within the past 24 months
* Provision of informed consent (checkbox in the survey)
* Residence in Poland (self-declared)

Exclusion Criteria:

* Age under 18 years
* No dive within the past 24 months
* No consent to participate
* Incomplete completion of survey sections A-C (eligibility, demographics, diving exposure)