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r/AdvancedRunning•
moongrey

Kidney Injury and Repair Biomarkers in Marathon Runners

Health/Nutrition

Hey everyone! I saw this study in r/science and figured I'd post it here. It's behind a paywall (I can probably email you a copy of the PDF if you want to read it), but the summary is useful.

Basically, researchers at Yale took blood samples from nearly two dozen marathoners before and after competing in the 2015 Hartford Marathon to look for biomarkers of acute kidney injury (AKI) and other tissue damage. While everyone's kidney function returned to normal, they did find evidence of AKI in the short term. So, the question remains whether repeated stressors to the kidney (and perhaps other parts of the body) during marathons will have lasting impacts down the road.

What do you think? Is this something you think/worry about?

Posted Mar 29, 2017, 3:18 PM UTC

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toaster800World's 2nd Fastest Stoner•

Sample size of the study is only 22 athletes. Until someone is able to recreate the results with a much larger sample, I would take any findings with a huge grain of salt.

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flocculus20 week marathon training cycles are super cool•

with a huge grain of salt.

Will that help or hurt your kidneys? I guess it depends how much you sweat and how much water you take in?

No I agree though, and I'd also be curious to see whether these were undertrained or experienced/well-prepared runners - maybe (probably?) that makes a difference in how much of a shock your whole system takes from a marathon.

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toaster800World's 2nd Fastest Stoner•

Absolutely. Fitness level, age, family history, previous running experience, etc. I think would all be major factors that could affect this. I can't imagine the researchers could control for these factors in their regression with only 22 samples.

7
tripsd•

There's always huge issues like this in medical literature, part of the reason its such a challenging area. Though this does seem like an area where they could get way better data if they wanted it.

5
Digital_Eide•

The thing is they conclude dehydration in marathon running can temporarily hurt your kidneys. Well cool. Couple of remarks:

The researchers indicate this is common in forms of unusually vigorous activity. The conclusion regarding running is thus cherry picking. Therefor the is no direct correlation with running, there's a correlation with strenuous activity in warm climatological circumstances. Running is an example of strenuous activity.

Second, there's no trauma of any kind. The organ can repair the damage. There's not really a structural problem here, other than one the researchers are suggesting.

The take away here to rest after a marathon (or any kind of strenuous activity), not that running actually does any permanent damage. That's a suggestion researchers want to investigate.

My problem with these types of research is that it really doesn't say anything about the risk/reward balance of running, nor does it add meaningfully to any discussion if long distance running is good for you.

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moongreyOPKeeping my clothes on•

Sure, that's definitely a limitation and one they acknowledge. I also think that any strenuous exercise, running or swimming or biking, will likely have short term damaging effects on organs.

3
Coloburn•

Actual line from the PDF: "Urine sediment pictures were taken using an Apple i-phone 6s camera." What a time to be alive.

I didn't get to read the whole thing, but seems like an interesting study. Definitely a small sample size, though that's a problem with these longitudinal studies, people either refuse because of the time commitment or drop out over time; and getting a ton of people is going to be real expensive. Even with the small sample size, 18 of the 22 developing ATI is pretty substantial.

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moongreyOPKeeping my clothes on•

I just noticed that line. How do you not have a microscope with a built in camera? From my experience, that's pretty standard. But hey, the microscopy looks decent so whatever!

It says they actually had 68 people meet inclusion criteria out of the 132 who took the survey, so you always wonder if the results would hold up with a larger n. People are definitely more expensive than animals, that's for sure.

One interesting tidbit that I hadn't considered is the idea of heat stress, something they talk about while comparing marathon runners to farm workers in Central America.

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All_I_Want_IsA_Pepsi•

You Don't take pictures of your urine with your iphone? Weirdos on this sub....

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Coloburn•

I do, but I have an iPhone 5s. And they disappear after 10 seconds.

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Winterspitebig shot in a small town race•

Biggest issue I had with it is they provided no details about the training the selected 22 had done and it's not well communicated that "oh yea, everyone was totally fine 48 hours later."

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moongreyOPKeeping my clothes on•

Okay I opened the PDF now that I'm in lab.

Re: training...

Runners who were aged 22 to 63 years and consented for research were included. Other inclusion criteria included normal body mass index of 18.5 to 24.9 kg/m2, at least 3 years of running experience, minimum of 15 miles of training per week on average for the last 3 years, completed at least 4 races that were >20 km in distance, and completed a previous marathon within the last 5 years within 50% to 70% of their World Asso- ciation of Veteran Athletes performance limit.

More detailed here:

Runners had a median running experience of 12 (IQR, 5.0-15.0) years and participated in a median of 5 (IQR, 2-16) prior marathons. Runners trained an average of 31.8 +/- 10.4 miles per week, and overall, the cohort was fairly healthy without comorbid conditions, except for 2 runners with hypertension and 1 with type 1 diabetes.

There were no long term follow-ups, though they cite a previous study that found that 2 weeks post-marathon, runners had returned to baseline kidney function and there's no evidence that running increases your chances of chronic kidney disease (but that may be because CKD is often asymptomatic and runners are usually healthy and don't get intensive check-ups often).

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YourInternetHistory19:23 5k•

Same post I made elsewhere:

Here is some stats based on someone who went from never running, to running an average for ~25 miles per week every week since August 2015.

Pre-Running 1 mile Numbers:

  • Albumin: 4.9
  • BUN: 17
  • BUN/Creatinine Ratio: 17
  • Creatinine: 1.20
  • LDL/HDL Raito: 1.1
  • eGFR Non-African-American: 83

After putting in 1543.6 miles in:

  • Albumin: 4.5 (this is better)
  • BUN: 20 (this is worse, shows kidneys aren't working as well as before but still in "normal range" granted it is the very highest in the range)
  • BUN/Creatinine Ratio: 19 (this is worse, shows kidneys aren't working as well as before but still in "normal range" granted it is the very highest in the range)
  • Creatinine: 1.07 this got better
  • LDL/HDL Raito: 0.7 this got a lot better
  • eGFR Non-African-American: 95 (actually shows increase in kidney abilities to filter blood)

My take away -- if you run a lot of miles, be sure to mention it to your doctor and ask him/her about the effects it can have on your kidney.

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moongreyOPKeeping my clothes on•

Thanks for sharing some personal info! Obviously everyone's mileage will vary, but I agree with your endnote. At the end of the day, this can be a big time stress on your body.

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kkrunsworld's slowest healer•

Interesting! I ran 22 miles about an hour before getting blood work (annual check up - I decided to combine a "sick day" with my long run...), and I definitely noticed some changes in my data in line with what you saw:

Post Run Stats:

  • BUN 19 (vs. average of 10 over three other visits)

  • BUN/Creatinine Ratio: 21 (vs. 13)

  • Creatinine: 0.92 mg (vs 0.82)

  • eGFR Non-African-American: 86 (vs. 98) - This moves in the opposite direction as your info

As a side point, the post long run data is literally from just an hour or so after running, whereas all my comparison data is from a point where I was also running (just not running immediately before my appointment).

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jw_esq•

I think there is zero to worry about. It's not like anyone should be surprised that running a marathon damages your body and you need a couple weeks to fully recover.

It's interesting from the standpoint of "here's how your body is getting beat up from extreme stress" but I think it wouldn't be fair to extrapolate this to the conclusion that distance running is bad for your kidneys, which is what popular media will probably do.

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moongreyOPKeeping my clothes on•

It's not like anyone should be surprised that running a marathon damages your body and you need a couple weeks to fully recover.

I don't disagree, but with the rising popularity of marathons with everyday people, these studies can help demonstrate that the preparation and recuperation parts are so important. I think it's crucial to continuously educate the general public who aren't regularly running, thus adapting to stressors over time, that marathoning expends a big toll on your body.

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kmck96NAIA bound•

I really don't worry about it. Acute means it comes and goes, and basically everything in your body is put under a ton of stress when you race a marathon so I'd be surprised if it didn't punish your kidneys.

It was so frustrating reading that comment thread, a lot of people were using this as an example of why marathoners should stop and it's so unhealthy and it's stupid to put so much stress on your body. Lots of uninformed opinions about things that people had no experience with ("I've never run a marathon, but those sugar and electrolyte shots are obviously harmful. You don't need electrolytes, you need water!). Mods went through and removed a ton of comments so it's a bit of a graveyard now, but it was rough when I saw it ~3 hours after it was posted.

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moongreyOPKeeping my clothes on•

Lots of uninformed opinions about things that people had no experience with

Sounds like a lot of r/science posts. I understand that Reddit isn't necessarily representative of everyday society, but the issue of injecting anecdotal or uninformed commentary doesn't help science or science education whatsoever, nor does it better the community who is interested in learning about the science. Typical people won't read the original paper, or even commentary by the authors as they attempt to bring it to the lay population; they may read a few top-level comments that got upvoted based on uninformed or misinformed ideas, develop their position, and be unreceptive to the nuances or true implications of the work.

Sorry I rambled on about this but it's something, as a scientist, that frustrates me and I want to be able to remedy.

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Startline_RunnerCounting down to Chicago•

Posted this in a sub-comment as well:

This is the very reason this is "sport" and not "exercise/activity". Sport is about pushing the human limits, it is beyond health. Everything is good in moderation, and this even applies to running.

Personally, I would rather have some minor health problems from running too much than working out too little!

3
ruinawish•

Thanks for not posting a clickbaity title.

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Crazie-Daizee•

Several studies have shown stressful activity over two hours is damaging even before this kidney study. Another factor is micro-tears in heart muscle that do not heal or strengthen like other muscles.

This is why I don't do marathons or ultras and try to take a quick "reset" break even on long runs if I know I am going to be two hours (one hour out, few minute reset + water, one hour back)

I may never do another marathon, not sure, I may reach a point I don't care about the damage and just want to do one if I am somehow still running at 55 or even 60

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Startline_RunnerCounting down to Chicago•

This is the very reason this is "sport" and not "exercise/activity". Sport is about pushing the human limits, it is beyond health. Everything is good in moderation, even applies to running sadly enough!

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Jakems•

Could you please post some info/research about micro-tears in the heart that never heal? I'd be interested to delve deeper into that.

2
Crazie-Daizee•

oh there is growing evidence for years, just google two hour exercise micro-tears

https://www.bostonglobe.com/lifestyle/health-wellness/2013/08/04/can-too-much-exercise-harm-heart-and-shorten-your-life/VLlkXGBN9f1t6raYmUSuPJ/story.html

this was surprisingly well written:

http://www.workoutplan.com/how-your-cardio-workout-could-kill-you/

Exercise is primarily directed at skeletal muscle – that’s the tissue that moves your body around. However, exercise also effects smooth muscle tissue such as your heart and the lining of your throat.

Your heart muscles get taxed, which is good, but, if they are overworked for too long, the muscles bulk up.

That reduces the volume of blood the heart can hold and pump. It also decreases the flexibility of heart tissue.

Worse yet, the micro-tears that appear in skeletal muscle when it’s stressed also form in the smooth muscle of your heart when it’s pushed to its limit.

if your heart isn’t given time to heal, and if you repeatedly indulge in vigorous cardio training, your heart can become riddled with patches of scar tissue.

1
Jakems•

Thanks for the info, it's been interesting to look into. It's interesting to see some of the research on it:

This study was referenced discussing people having been hospitalized at some point since 1989 for an "irregular heartbeat" due to their participation in a cross-country skiing event, but the only irregularities were bradycardia and atrial Fib.

I haven't looked at information about scar tissue on the heart, but I thought that there were actually three types of muscles in the body: skeletal, smooth, and cardiac. So the heart would be made up of cardiac muscle, but I'm not sure how scarring would occur—I thought that could only be from things like heart attacks? That would be interesting to find out more about!

Personally, I feel like you can obviously damage the heart in many different ways, but I'm having trouble wrapping my mind around a specific time-frame of two hours. I mean, our hearts never stop beating. Ever. Sometimes the beats per minute change, and the stroke volume changes. But the stroke volume levels off right around 75% of VO2 max

So would the risk be from the stroke volume increase? Or blood pressure? 160ish bpm (75% VO2 max) really isn't too crazy to do even in a workout, and competitive Olympic lifters, powerlifters, and gymnasts can put way more stress on their heart in an instant when they brace during a lift—taking their BP to 345/245 mmHg!!! Wowz. Even during intense aerobic exercise the heart never gets up to BP's that high. That's why lifters have a thicker heart (specifically the left ventricle chamber walls), but endurance athletes have a bigger heart (specifically the left ventricle again, except the radius increases not just the thickness)

Thanks for the info! You inspired me to start looking around research periodicals and stuff again. Ah, so satisfying :)

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Crazie-Daizee•

I'm impressed and enjoying your enthusiasm

as a side thought, since I am a masters-age athlete, I also have the daily perspective of unavoidable reduced max heart rate every year and that no amount of training, medication or operations can ever get around that fact - it slowly crushes vo2max as you get older

my max now I have ever seen in a race, going up a hard hill repeatedly is 171, which makes me sad - in training I cannot get it over 160

but I'm not sure I've ever seen explained WHY the heart rate limit draws down as you get older, perhaps it is related to that scar tissue, as the heart muscle loses flexibility and can never be "stretched out" again like other muscles

gosh if they could solve that in my lifetime, wow

1
ajlark25Pretty fit for a big guy•

"The good news is that you are probably in no danger. Unless you are doing two hours or more of intensive cardio training every day, you are not at risk. So keep jogging – exercise is still good for you"

Even these articles say it you recover properly you're at little risk though. I'm probably biased because I want to do ultras, and I'm still in my invincible 20s, but it seemed like these articles warn against overtraining more than anything. Definitely something we should be aware of, but training plans (and this sub) usually advocate recovery days during training and after races.

1
Crazie-Daizee•

but how do you know you have enough recovery for your heart?

if you have good insurance and can get blood tests to see how screwed up things might be getting, go for it - though that still won't tell you if your heart is healing properly

unfortunately I can't afford insurance for decades so I can't risk it

I run two hours a day and stop, I won't go further, and then I don't run the next day, I do cycling instead which is lower heart rate zones for me and non-impact - I even try to split all my activities into one hour segments, hour out, hour back - or like today I did 5K repeats so I waited until my heart rate dropped after each one for a few minutes

here's another article indirectly related you should read

https://www.sciencenews.org/blog/scicurious/slow-heartbeat-athletes-not-so-funny

apparently I am headed for a pacemaker in the next decade

2
da-kineHI•

Late post is late. Scanned the PDF quickly though I don't have a background (or really know anything) about health. A few questions and take aways.

AKI was defined using AKI Network (AKIN) criteria. Stage 1 AKI was defined as a 1.5- to 2-fold increase or 0.3-mg/dL increase in serum creatinine level from day 0 to peak creatinine value on either day 1 or day 2, and stage 2 AKI was defined as a more than 2- to 3-fold increase in serum creatinine level

So they're comparing this serum creatinine thing the day before the marathon, immediately after finishing, and the day after the race. Is it possible that marathon race prep could reduce serum creatinine below baseline levels? My main concern is that on day 0 you're at a very high level of hydration and your glycogen stores are as full as possible from carb loading, and then at day 1 you're very dehydrated (maybe in some cases suffering from hypernatremia?) and your glycogen stores are totally depleted. So you get this artificially high increase relative to if you were to compare day 1 to say day -7 or day -30 during more "normal" hydration and training loads? I have no idea

Also I'd be curious to see how different nutrition or hydration strategies impact the kidneys. Can you avoid this by taking in more nutrition or drinking more?

Assuming the results are correct what are the policy implications for marathon recovery? Should you avoid alcohol for several days after your marathon? Anything else that might stress the kidneys?

Also side note:

11 (50%) were taking herbal supplements

Are you guys taking herbal supplements? WTF are herbal supplements?

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