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.研究背景：本研究旨在探究并驳斥「餐后立即游泳存在危险」的固有认知，同时探讨餐后即刻游泳可能引发的生理变化。此外，本研究拟探索试验可行性并获取基础数据，用于后续大规模随机试验的样本量计算与结局指标遴选。 研究方法：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。受试者于试验首日被随机分配至两组：一组于午餐后即刻进行14米蛙泳，另一组则于餐后等待30分钟再游泳；两组受试者于试验次日开展交叉试验。本研究的主要结局指标包括死亡率、情绪状态、不适感与不良事件，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《青少年情绪状态量表（Profile of Mood States-Adolescents）》、不适感视觉模拟量表（visual analogue scale）以及不良事件问卷。 研究结果：共计26名受试者完成本试验。本研究未报告任何死亡、溺水、心肺复苏、侧腹痛或肌肉痉挛病例。受试者两次游泳后的情绪状态无显著差异，游泳时长亦无统计学差异（P=0.53）。但相较于餐后等待30分钟再游泳，受试者在餐后即刻游泳时报告的不适感显著更高（P=0.05）。 研究结论：本研究未观察到死亡或肌肉痉挛病例，提示餐后游泳似乎具备安全性。但受试者在午餐后即刻游泳时，报告的不适感显著升高。本可行性试验为后续开展大规模随机试验提供了基础数据支撑。