To swim or not to swim after eating: a randomized controlled crossover feasibility trial

Background: The aim was to investigate and challenge the belief that swimming immediately after eating is dangerous and also to investigate what potentially could happen when swimming immediately after a meal. We wanted to explore feasibility and get background data to perform sample size calculations and choose outcome parameters for a full-scale randomized trial. Methods: The trial was performed during lunch breaks at a medical writing course in Turkey in June 2022. Participants were randomised on the first trial day to swim 14 meters breaststroke immediately after lunch or wait 30 minutes after eating, with crossover on the second trial day. Main outcomes measures were mortality, mood, discomfort, and adverse events were assessed in participant-reported questionnaires. Participants completed a Profile of Mood States-Adolescents questionnaire, a visual analogue scale for discomfort, and a questionnaire of adverse events after each swim. Results: A total of 26 participants completed the trial. No cases of mortality, drowning, resuscitation, side stitch, or muscle cramps were reported. The participants reported no significant difference in their mood states after each swim and no significant difference was found regarding the participants' swimming time (P = 0.53). However, more discomfort was reported when swimming immediately instead of 30 minutes after eating (P = 0.05). Conclusions: It seems that swimming after eating is safe since no mortality or cramps were registered. However, a significant level of discomfort was found when swimming immediately after eating lunch. This feasibility trial provides background data for a future full-scale randomized trial.背景：本研究旨在探究并质疑「餐后即刻游泳存在风险」的固有认知，同时探索餐后即刻游泳可能引发的生理变化。本研究拟验证试验可行性，获取基础数据以用于后续大规模随机对照试验（full-scale randomized trial）的样本量计算与结局指标遴选。 方法：本试验于2022年6月在土耳其某医学写作课程的午休时段开展。试验首日，受试者被随机分为两组：一组于午餐后即刻游泳14米蛙泳，另一组则于餐后等待30分钟再游泳；试验次日采用交叉设计更换干预分组。主要结局指标包括死亡率、情绪状态、不适感及不良事件，均通过受试者自评问卷进行评估。受试者需在每次游泳后完成青少年版心境状态量表（Profile of Mood States-Adolescents）、不适感视觉模拟评分量表（visual analogue scale, VAS）以及不良事件调查问卷。 结果：共计26名受试者完成全部试验流程。试验期间未报告死亡、溺水、心肺复苏、岔气或肌肉痉挛病例。受试者两次游泳后的心境状态无显著差异，游泳时长亦无统计学意义上的差别（P=0.53）。但相较于餐后等待30分钟后游泳，餐后即刻游泳时受试者报告的不适感显著更高（P=0.05）。 结论：本试验未观察到死亡或肌肉痉挛等严重不良事件，提示餐后游泳具备安全性。但餐后即刻游泳会导致受试者不适感显著升高。本可行性研究可为后续开展大规模随机对照试验提供基础数据支撑。