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7482 Views 5 Replies Latest reply: Jun 4, 2012 2:36 AM by DarklingThrush
longislandguy Pro 121 posts since
Dec 31, 2009
Currently Being Moderated

Apr 10, 2010 5:44 PM

low grade fever after run

I'm training for a my first marathon next month and have found that after my long runs (18-20 miles), I have been getting a low grade fever (99.5) that lasts several hours after I finish.  At first I thought it was dehydration but I have been paying special  attention to staying hydrated.  Temp today was high 50's.


Anyone else expereince this?

  • grid-rider Legend 235 posts since
    Sep 5, 2009
    Currently Being Moderated
    1. Apr 10, 2010 7:15 PM (in response to longislandguy)
    Re: low grade fever after run

    Running is stress on the body and overtraining without sufficient recovery could trigger an autoimmune response. The body doesn't get back into balance so it fights itself...good sleep is best.

  • Urbster Legend 760 posts since
    May 27, 2008
    Currently Being Moderated
    2. Apr 11, 2010 4:49 PM (in response to longislandguy)
    Re: low grade fever after run

    When my weekly mileage increases over 20 my overall body temp increases.  I feel like I have a fever but I don't have a thermometer so I can't be sure.  I don't feel sick, although it usually precedes an overuse injury so I back down my training a week and it goes away.  I never heard of anyone else experiencing this, mine lasts for days, my doctor said he never heard of such a thing but it doesn't bother me at all.  

  • lenzlaw Community Moderator 10,539 posts since
    Jan 18, 2008
    Currently Being Moderated
    3. Apr 11, 2010 5:25 PM (in response to Urbster)
    Re: low grade fever after run

    My intuition tells me your body temp rises during exercise, and I seem to recall reading something about it in the past.  I googled temperature after exercise and got a number of hits, some of which might help explain what you're seeing.  Here's one:, which says:


    "You sweat more after you finish exercising than you do while you exercise. More than 70 percent of the energy that powers your muscles is lost as heat, causing your body temperature to rise during exercise. To keep your body temperature from rising too high, your heart pumps the heat in your blood from your muscles to your skin, you sweat and it evaporates to cools your body.

    Sweating is controlled by the temperature of the blood flowing to the part of the brain called the hypothalamus. When your temperature rises, you sweat more. During exercise, your heart beats very rapidly to pump blood to bring oxygen to your muscles and hot blood from the muscles to the skin where the heat can be dissipated. When you stop exercising, your heart immediately slows down, decreasing the amount of blood pumped to your skin, so your temperature rises higher and you sweat more."


    I don't know that this would explain temperature being elevated for an extended period of time, such as Urbster seems to have experienced.




    EDIT:  This one may be more relevant since it involves extended exercise:


  • MyBodyStrong Rookie 1 posts since
    Oct 16, 2010
    Currently Being Moderated
    4. Oct 16, 2010 8:20 AM (in response to lenzlaw)
    Re: low grade fever after run

    An elevated temperature may be due to a build up of lactic acid.  This happens when your body can't create enough creatine (or maybe it is creatinine?) to keep up with the demand that you are putting on your body.  At this stage you go from aerobic exercise to anerobic exercise.  I'm also a runner and I also use programs such as P90X, I know the importance of a well-balanced meal plan and nutritional/recovery substances immediately after and sometimes during workout.  It was when I stopped using those specially designed meal plans and recovery formulas that I started having a low-grade fever.  I went to the doctor, tried antibiotics, but I still was running the fever.  Once I got back on track with my nutrition, I started feeling much better.  I also noticed that I was getting slightly inaccurate temp readings from using a forehead temporal artery thermometer as opposed to the normal "under the tongue" kind.


    Whether you have a temp or not, it is critical to give your body the fuel it needs if you are going to push yourself so hard. I would suggest setting up an online meal plan (if you go to my website you'll find tools to help you) and then consider trying something like the P90X recovery drink which will give your body just what you need after a hard workout, including creatine.


    I hope that helps!  Keep on running!  --- And, always consult your physician


    Coach Jennifer

    Independent Team Beachbody Coach

  • DarklingThrush Rookie 1 posts since
    Jun 4, 2012
    Currently Being Moderated
    5. Jun 4, 2012 2:36 AM (in response to longislandguy)
    low grade fever after run

    I found this thread searching because I've had the same experience. Haven't seen any anwers which seem adequate. I'm 48, in great health, and no stranger to strenuous exercise. I can't be getting dehydrated because I'm still having to stop and pee and my urine looks perfect (clear light yellow). I don't experience this feverish feeling after every long run, and it's not debilitating when I do; I was just curious about what I was feeling and wanted to learn more. Occasionally, after runs of 15 miles or more, I start feeling a little feverish. Typical pattern:


    1) Wake up, eat a bowl of oatmeal, drink some water.

    2) Load my bike with full water bottles, a carton of chocolate milk, a cliffbar, some cliff shots (gels - I use the ones with 50mg caffiene, equivalent to one cup of coffee).

    3) Bike to the trailhead at a lake I live near.

    4) Consume one Cliffshot, drink some more water.

    5) Run anywhere from 7 to 23 miles, depending on how I'm feeling. I carry one water bottle with me, which always lasts long enough to get me back by my bike (which I pass every 7.5 miles).

    6) When I pass my bike (aid station  ), I eat a bit of cliffbar, a cliff shot, and top off my water bottle.

    7) Finish my run and walk around while drinking chocolate milk.

    8) Wade at least knee deep in the lake to chill my calves and feet.

    9) Bike home.

    10) Rest, eat, self-care - and just occasionally (like today), a mild feverish feeling. Not enough to be a serious concern, just a curious desire to skip everything else and climb under a blanket for a few hours.


    Some days there are bananas mixed in there; today there weren't. Maybe potassium is a clue? Some days I drink iskiate (Tarahumara drink with chia seeds, lime, and sugar); I had some today.

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