Study Reviews Swimmers’ Heart Health Versus That Of Runners

by Retta Race 12

April 29th, 2019 Lifestyle, News

If you’ve ever wondered how the act of swimming affects your heart compared to land-based activities, a recent study may be of interest to you.

Published in Frontiers in Physiology last November, a study conducted by researchers at the University of Guelph in Canada and other institutions took a look at the structure and function of elite swimmers’ and runners’ hearts.

Swimming is unique in the fact that our bodies are immersed in water, are in a prone position and both upper and lower limbs are involved. Add in the fact that breath holding is a big component of the activity and swimming is truly a different animal than, say, running or rowing.

Swimmers involved in the study were recruited at the 2016 FINA Short Course World Championships in Windsor and were tested upon completion of all competitions. Runners were recruited during the competitive season from an elite local club near the University involved in the study. Sixteen athletes were included in each group, and they were matched based on age, sex, and race.

Although the study proved that exercise is healthy for hearts, no matter on land or in the water, small differences were indeed discovered, such as the left ventricles of runners’ hearts filling back with blood earlier than average and untwisting more quickly during each heartbeat. ‘In theory, those differences should allow blood to move from and back to the runners’ hearts more rapidly than would happen inside the swimmers.’

However, as swimmers ‘exercise in a horizontal position, their hearts do not have to fight gravity to get blood back to the heart, unlike upright runners.’

You can read more about the findings both in The New York Times’ summary, as well as via reading the study itself here.

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I read this study before, Wonder about trialatherles at the elite level,

2 Cents

Probably more like runners since the upright position is about 11/12th of the whole race…. Swimming is disproportionate to the biking and running in the amount of time it takes to complete a triathlon. Times are usually in the ratio of (or close to) 1:6:5 (swim:bike:run).


Really? The bike is leaning over


Only 16 participants each? Isnt that a bit low

2 Cents

Yes, plus it was the top of the sport for swimmers, and not for runners. It was a club team and probably not at world championship level.

Overall, I am shocked this was picked up by the NYT, or even made the news. The only thing it found was that exercise was good for the heart. Readings were only done once and during rest. Without getting into all the technical jargon about stats and what makes a study legit, etc…. this one does not pass the test.


You missed several conclusions. There is no such thing as “what makes a study legit” (there is no arbitrary categorization – this study is “legit”, this study is “not legit”; there are infinite and sometimes subjective gradations of more or less informative). Sample size adequacy is not determined by “hmm, that seems low” – it is determined by power calculations driven by goals of the researchers – avoiding type I or II errors, estimated/predetermined differences in variables, type of statistical analyses performed, etc. 16 participants may or may not be perfectly valid. And the runners chosen were described to meet the criteria “an athlete currently competing at the Olympic or International level, or specifically identified by their national sporting group… Read more »

2 Cents

Except if your population is “world class swimmers” and “elite level club runners” (even if those elite level runners are national team members… thats like saying those who finish anywhere from 4th to 50th at OTs in swimming are close to those who finish 1-2) then 16 is very small and does not make the results viable. How many swimmers were at that world champs meet?? More than 160, and probably more than 320, meaning that the selected sample (which we didnt even get into how they were selected… truly random or self selected… ) is less than 5%. Plus the club runners are all from one part of the world whereas the world champ swimmers were presumably from all… Read more »

Coach Coach

It sounds like your understanding of research may be based more in the social sciences where randomization is incredibly important. Ex phys research, especially of elite athletes, doesn’t often have that luxury. Judgenot is completely correct. There are varying degrees of “legitness” within research. I hardly have an issue with 16 participants on each side. As for its conclusions – like 99% of all research done in the history of humanity, this creates more questions than answers. Comparing elite athletes to semi-elite doesn’t mean its “bollocks” it just means they compared elite athletes to semi-elite athletes. Analyzing the heart at rest doesn’t mean they are looking at the wrong things, it just means they looked at the heart during rest.… Read more »


Well the Swim Swam heardline is incorrect. this is not compare the health of either heart. It simply described function (runners had better diastolic function and ‘untwisting’. There is no conclusion if this is more healthy or not. That would require an longitudinal study.

Coach Coach

Agreed. Articles like this are important in disseminating information from researchers to coaches and athletes, but the further it gets from the researcher the more inaccurate things can become. Loretta’s claim that the study “proved exercise is healthy for hearts” is untrue as “healthiness” was never measured in this study.

Coach Coach

Unfortunate how many people are upvoting this comment. Research isn’t perfect, and the two issues you bring up about sample size and the eliteness of the participants do not discredit the article. The point of research is to learn about something specific and help inform future research. You seem to think the article should discover something that revolutionizes how athletes train, but the purpose of this article is simply to say “we found a difference between elite swimmers and semi-elite runners in LV peak untwisting rate and a few other measures. Do with that what you will.”


I can’t help but wonder how the timing of the testing may have affected the results. The swimmers where taken directly after a competition, while I assume the runners were not so. Could their taper and/or proximity to competition have affected their electrocardiogram results? Legitimately curious if anyone has any info or studies comparing in-season and taper heart performance.

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