# Unintentional Water Intake During Swimming and Post-Race Gastrointestinal Illness in Triathletes: Results from 6 Triathlons and 1294 Athletes

## TL;DR

Swallowing water during triathlon swims increases the risk of gastrointestinal illness, highlighting a need for better water quality monitoring and athlete protection.

## Contribution

This study is the first to quantify the association between unintentional water intake during triathlons and post-race gastrointestinal illness in a large sample of athletes.

## Key findings

- 75.3% of triathletes reported unintentional water intake during races.
- Athletes who swallowed 1-3 sips of water had 3.7 times more gastrointestinal illness.
- Those who swallowed 4 or more sips had 5.1 times more gastrointestinal illness.

## Abstract

Public health relevance—How does this work relate to a public health issue?
The study suggests that water intake during the swimming part of triathlons may be an exposure route for gastrointestinal illness, underscoring a recurrent environmental health risk in recreational water sports.

The study suggests that water intake during the swimming part of triathlons may be an exposure route for gastrointestinal illness, underscoring a recurrent environmental health risk in recreational water sports.

Public health significance—Why is this work of significance to public health?
The observed relationship between the amount of water intake and post-race gastrointestinal illness may indicate limitations in current water quality monitoring practices and the need for improved athlete protection.

The observed relationship between the amount of water intake and post-race gastrointestinal illness may indicate limitations in current water quality monitoring practices and the need for improved athlete protection.

Public health implications—What are the key implications or messages for practitioners, policy makers and/or researchers in public health?
The findings support the implementation of more frequent, near-race water quality monitoring and the development of athlete-focused preventive strategies to reduce unintentional water intake during open-water swimming.

The findings support the implementation of more frequent, near-race water quality monitoring and the development of athlete-focused preventive strategies to reduce unintentional water intake during open-water swimming.

This study aimed to investigate the relationship between water intake and post-race gastrointestinal illness in triathletes. Following a post-event survey approach, we evaluated the association between water intake and gastrointestinal illness in triathletes. We collected data among participants of six different triathlons in the Netherlands using an online questionnaire about personal characteristics (age, sex, swimming experience, chronic illness, and athletic level), the completed triathlon (length and duration), water intake, and illnesses during the 7 days following the triathlon. The associations between water intake and gastrointestinal illness were analyzed using generalized estimating equations logistic regression. In total, 1294 athletes participated in this study. The average rate of gastrointestinal illnesses per triathlon was 5.1%. In total, 75.3% of the athletes reported water intake during the race. The associations between water intake and gastrointestinal illnesses were significant. Triathletes with one to three sips of water intake reported 3.7 times more gastrointestinal illnesses (OR = 3.672, 95%CI: 1.316–10.242, p = 0.013) compared to those who did not ingest water. Triathletes with four or more sips of water intake reported 5.1 times more gastrointestinal illnesses (OR = 5.070, 95%CI: 1.740–14.767, p = 0.003). In conclusion, water intake was associated with an increased risk of post-race gastrointestinal illness. The results advocate for improved water quality monitoring and preventive measures in triathlon.