Week 7 Blog Post

I decided to write about a NY Times article titled “The Heart of a Swimmer vs. The Heart of a Runner” by Gretchen Reynolds.

It’s already a known fact that exercise changes the workings of your heart, it particularly strengthens and enlarges the left ventricle with the increase need for oxygen. However, is there a difference between constantly swimming and constantly running?? A new study in Canada researched the hearts of elite swimmers and runners, they used elitist because they would have been doing these activities for years at high levels and will show an exaggerated difference in the structure/function of the heart. This makes it easier for researchers to see and prove the differences. They took 16 swimmers and 16 runners of different distances specialties, they asked them to visit the lab after not exercising for 12 hours and then to lie quietly. Both had superb heart health, and all had large efficient left ventricles. However they did find a subtle difference, runner’s hearts were able to fill with blood earlier than average and untwist more quickly than those who swam. This could be attributed to the fact that swimmer don’t have to fight gravity during exercise to get blood back to the heart, so it’s uncertain that it gives runners an advantage in that aspect. However, it’s very interesting to see how the slight difference in exercise can change the makeup and function of our bodies so easily! I wonder if their lung capacity and lactate threshold differ as well because they may not be affected by gravity, like the heart is.

2 thoughts on “Week 7 Blog Post

  1. Really cool article! This is a fairly recent article and I’m surprised this wasn’t investigated sooner. I have never though about how the structure of the heart may change (though it makes sense to me now). I’ve always thought that it could become more efficient but not physically enlarged. It makes sense why the left ventricle is the enlarged portion of the heart considering it is responsible for receiving the oxygenated blood from the lungs and delivering it to the body.

    What I also found interesting about this article was that the left ventricle of rowers had an even greater muscle mass than that of runner or swimmer. This is potentially because rowing is a combination of power and endurance. But this made the heart less nimble; less efficient in that twisting motion.

    I wonder how consistent the results where and what their sample size was. I am sure there must have been some variation among individuals!

  2. Hi Morgan,

    Nice post, it is especially interesting because both exercises can be endurance and both can be sprints, depending on the distance of the event. Of the 32 athletes that the researchers sampled, I would like to know how many were sprinters and how many endurance athletes. I would also want to know if the researchers chose the same amount of endurance swimmers vs. endurance runners and sprinting swimmers vs. sprinting runners. I would expect the intensity of training in either sport to affect the heart differently. Also, how did the researchers measure heart health? I think this article illuminates the nature of lay articles – many important details are lost for simplicity’s sake.
    When you mention the subtle difference that they found – that runners’ hearts could fill earlier and ‘untwist’ more quickly, does untwisting refer to the relaxation of the ventricles after a contraction? And filling early, does this imply that the atria are also more powerful as they are now able to push blood into the ventricles more quickly?
    That is really interesting that gravity comes into play. I would not have thought that being in an upright position vs. a horizontal, swimming position can actually affect the changes developed in the heart during exercise! In terms of lung capacity, I bet swimmers have better lung capacities on average because most of the race they are unable to breathe! I would imagine that the efficiency of their lungs is greater – they are forced to get more oxygen out of the air they breathe, since air is not always available. I would also venture to guess that swimmers have a greater hematocrit – more red blood cells and hemoglobin than runners as to deliver more oxygen with each breath. Of course, I could be completely wrong here, I am simply speculating, but it reminds me of those divers in Endure who trained by exercising while holding their breath. Also, swimmers must experience the ‘dive reflex’ when they compete – their heart rate must slow down to conserve oxygen. Obviously competitive swimmers end up with high heart rates by the end of competition, but I bet the heart rates are slower than an equivalent amount of work done during running! If true, I suppose swimmers’ hearts would have to be more efficient with each beat (higher stroke volume). Maybe this is true, maybe not, but it is interesting to think about. Thanks again for your post, and see you in class tomorrow!


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