Any runners out there?


I'm interested to hear from fellow runners. Who have underactive thyroid. It's affected my running & my half/full marathon times since being diagnosed in March 2012.

I often have heavy/tired legs almost like I've ran several marathons in a day. I feel this is somehow connected to my thyroid as I never had this before. I have told the doctor but they always dismiss it as not being thyroid related. I have no other symptoms.

Yours thankfully


12 Replies

Hi Wayne,

I am sorry you are not feeling as well as you used to. I have looked at your profile but you haven't given any info, i.e. when diagnosed, medication, dose although I see from above you have an underactive thyroid i.e. hypothyroidism.

To get well we have to read and learn as much as possible about our condition, in order to get better. By now you will probably have sussed out the doctors appear not to be the best people who understand about the function of the thyroid gland, nor some Endocrinologists, more's the pity.

If you have had a recent blood test for your thyroid hormones, get a print-out from the surgery with the ranges and post on a new question for comments. If you've not had a recent one, please make an appoint as early as possible, and don't take levo before it, take it afterwards. Do you take levo first thing with 1 glass of water and not eaten for around an hour, so that the uptake of levothyroxine isn't affected. Also ask for a Vitamin B12, Vit D, iron, ferritin and folate as we are usually deficient and these need to be at an optimum too - not just 'in range'.

Re your running (I am not an athlete). Our body and thyroid receptor cells need an optimum dose of thyroid hormones (levothyroxine, natural dessicated thyroid hormones or T4/T3 (levo plus liothyronine - the two main hormones) to work normally and efficiently. Sometimes levothyroxine doesn't work as well for some people into converting to sufficient T3 (the active hormone). Levo (T4) is inactive.

No matter what your GP says, (they don't know) when we exercise it depletes our T3 which in turn causes symptoms, I assume like you have above. If we are not underactive our body replaces what we have used up but if hypo, because we are 'low' anyway and adding hormones which our body cannot replace normally so we have to have an optimum thyroid hormone for us to function as we want to. That's easier said than done as levothyroxine as been promoted as the only replacement for hypothyroidism. Those of us on this site have found that we don't necessarily get well on levo but some have found the benefit of an addition of some T3. Others have moved onto T3 alone or natural dessicated thyroid hormones (these used to be the ones we all got before the blood tests were introduced along with levothyroxine) (a synthetic hormone).

I note you say you have no other symptoms on levothyroxine and am glad that that's the case.

This is an informative link:

Wayne, If you post your recent thyroid blood results with the lab ref ranges (the figures in brackets after your results) and say what dose and medication you are taking members will advise whether you are optimally medicated.

Ask your GP to test ferritin, vitamin D, B12 and folate as hypothyroid patients are often deficient/low and these deficiencies can cause musculoskeletal pain, fatigue and low mood similar to hypothyroid symptoms. Post your results with the lab ref ranges (the figures in brackets after your results) in a new question and members will advise whether supplementation is required.

In addition to the great answers above. I'd generally supplement with nutrition that supports mitochondrial function (these are the battery packs of every cell in the body, that the thyroid also regulates). These would be magnesium citrate, B-complex, vitamin C, zinc, omegas 3+6, co-Q10 & D-ribose. If you're low in any of these nutrients, your sport performance will be compromised too, because your mitochondria won't be making the energy required to sustain your energy requirements. Hope this helps. :-)

Hi, I would just like to add that you probably are low in these nutrients - and all the others - because hypos tend to have low stomach acid, and therefore difficulty absorbing nutrients. Check out iron, ferritin, vit D and zinc, too.

Thanks for that greygoose


Hi Wayne

Sorry to hear that your not feeling your best. I too used to run a lot - 15 miles a day sometimes struggle with even 3 miles some days. I work out for at least an hour, 6 days a week but since being diagnosed hypo my workouts have become very Hard. Low energy and heavy tired legs (sometimes I dont think I will make it back from walking the dog my legs are that heavy - like walking under water). I'm newish to the forum Wayne so the others will be able to help you heaps more but for me, since they started me on iron supps. - 6 weeks ago things are getting a bit better. I was very low - but not anemic- so maybe get your ferratin checked. goodluck and I hope you feel better soon

I remember reading an academic paper about someone who trained a bunch of Huskies to pull a heavy sledge or something and found that their thyroids worked less well after training than before. I'm not trying to say that you are like a Husky but just to point out that sustained intense physical exercise can be associated with the onset of hypothyroidism. Many people on this forum who have hypothyroidism find that they can't train as well as they used to unless they increase their medication. Since you are being treated you should be aiming for a TSH of around 1, possible lower. Exercise seems to use up T3 which would leave you feeling tired. There are 'food supplements' like Thyro Gold which contain low levels of both T4 and T3. You may find that taking some of these before or just after exercise helps (and it doesn't really count as self medication). If your doctor seems unwilling to help you may need to do some trial and error yourself to improve things. All the best!

Thankyou So much eeng

There's so many knowledgable people on here all so kind & helpful.

I have often wondered if I need to be on more due to my training.

Although my doctor always tells me I'm within the range.

But my legs feel like I've run even before I start running.

Like tired legs


In my experience this is absolutely related to thyroid issues and when I was running (during my brief period of wellness) I used to time it so I took my t3 shortly before setting off. I was only doing run/walk three miles twice a day (not endurance running) but it *really* helped with strength and stamina.

I had an inexplicable relapse and haven't been able to get back to running despite t3 levels being good etc, but I am always hoping. Having had this period of wellness I am eager to experience it again. I have read posts by others here about having to reduce/discontinue their running regimen due to 'heavy legs' and I have no doubt it is related.

Not only do you need to get your hands on your test results and post here as recommended but you may want to consider a trial of t3 in addition to your levo.

Hi Wayne

Im new to this. Diagnosed about 6 weeks ago. I am/was a very keen runner. I picked up an injury ( high hamstring ) a couple of years ago. It never properly recovered, despite lots of intervention and my running has dwindled down to very little. I have found that i get heavy, achey legs. I wondered if you had any success since you posted.

I am very keen that my lack of recovery progress was linked to my thyroid and fingers crossed it will all feel good soon.

Ive just swopped from Levo to NDT so am hopeful the T3 will help.

Any tips appreciated.

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