Are lows while exercising ruining your physical fitness?

I never stop what I´m doing if I get low (excercise or other things), I just push through. But I´ve started to wonder if this is just not good for me. I just listened to the Juicebox podcast #26 with Kris Freeman (Olympic cross country skier) and he said the following:

“Every time I went low I was just crushing myself for my next training session. I´ve actually experienced adrenal fatigue a couple of times in the racing season. Once I get adrenal fatigue I might as well pack it in for the season because it´s not comnig back until I´ve rested a couple of months. And every time I get low I´m wasting adrenalin.”

I´ve also heard from another type 1 that a physiotherapist had told him to just pack it up if he gets low while excercising, walk slowly home and rest. If not he would just ruin what he was trying to bulid. He had started doing that and said it worked for him.

Any thoughts? Informed knowledge of how this works? I´m hesitating following the advice because I rarly do anything physical without going low to the point where I release adrenalin.

There are a couple things wrong with Freeman’s comment.

First of all, in general, T1’s who have had the disease for long enough time do not have a cortisol response to a low BG. That’s why you might sleep through a low BG at night.

In non-diabetics, the counter-regulatory responses to hypoglycemia include cortisol, epinephrine, glucagon, and growth hormone. But in diabetics, those responses become diminished.

Second, the idea of adrenal fatigue is somewhat pseudo-scientific at this point. The whole concept was conceived by James Wilson…a chiropractor.

But hey, guess what! The chiropractor has a book about it. And he sells the book! For money!


I know that the idea of adrenal fatigue is disputable, but if you overlook that part,- is it still a valid point to say that you´d be better off quitting if you get low during excercise?

I suspect it´s true based on my own experiences and that it somhow is taxing on your body to get low, and maybe it should be a good advice to get enough recration after a low. Like a general advice for diabetics to avoid burning out.

I think there could be safety concerns. Those could be valid if a person is not treating it quickly and properly.

It is harder to run when low, certainly that is true. And your body will tap into your other fuel sources more.

If you do not have sufficient glucose in your blood, there is no glycolysis, which is the process where glucose is broken down to create energy. So your body has lost a source of fuel. It has to rely more on muscle glycogen and fat metabolism.

But running when low can also hinder fat metabolism! Running when low means you have no carb metabolism happening. In order for there to be fat metabolism, your body needs oxidation of Acetyl CoA in the Krebs cycle, and that requires a derivative of carb metabolism (oxaloacetate). So when carb metabolsim is completely absent, efficient use of fats for fuel is hindered.

So yes, running when low is going to be harder, and will use up more muscle glycogen than you would otherwise if you were able to take in carbs and use them. And less ability to utilize fat as a fuel.

But as long as you replenish your muscle glycogen when you are done - meaning eating enough carbs to restore - I don’t think it would affect you much on the next day. I have never noticed it being a problem, but I do eat plenty, so maybe that is a difference.

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I am a walker and not a runner but I will tell you what I do while walking. I will some amount of high sugar drink if my BS is on the lower side of normal. I will lower my basal down to 40% of normal. I also carry small gel pack that contains 15 grams . For me its the prep before walking.

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Thanks for the advice, @DonR, I know you mean well, but it´s not what I asked. I have my preps and know what to do but I almost always ending up going low at one point or another in the course of a five hour excercise session of some kind. Not always, off course, but often enough and I just push through.

And my question is if it´s harmful to your body to continue doing what you´re doing when you get low. It could be houskeeping and not regular work outs for that matter. A doctor, an exercise physiologist (Kris Freemans people) and a physical therapist (friend of my type 1 -frien) has now all said the same,- quit what you are doing, turn around and walk slowly home and get some rest and restituion.

So why could it be harmful? How long should you restitute? Anyone who has further insight other than it´s what you should do?

I’m confused; you told DonR that he wasn’t addressing your issue, and that you state that you “know what to do” “but I almost always ending up going low…” To me that says that you haven’t gotten a handle on the issue of exercising without going low. I used to be unable to accomplish that, but now I can. It takes a lot of practice and feedback from what works and what doesn’t. I’m fully in support of what DonR told you.

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I see your point, but me getting low or not is not what I’m asking advice for here. That’s a whole other topic and not something I can do much about due to other circumstances. That’s why I’m adressing a topic I can do something about;- stop excercising if I get low. If there is any truth in what people claim,- that it will help me not ruining what I’m trying to build being physically active.

ah, OK. Here’s what I do. Keep in mind I’ve been diabetic since prior to 1978–that’s when I was DX’d and placed on insulin. I’ve had thousands upon thousands of lows since then. Countless lows AAMOF. So many that when I’m busy doing heavy yard work and can feel that I’m low and/or my Dexcom alerts me, I tend to keep on working. If I start getting central-vision blindness from a low, then I know I should get my butt into the house and eat some fast carbs. So, I’m sorta of doing what you do–“pushing through”. I do that all the time. Prior to 1996 when I got my first pump, I’d panic so much when I got low because they were truly “killer” lows–often I’d drop 100 points in 5 minutes–no joke. So I’d not put off eating/drinking carbs if I was low back then, but now…I “push through”. :slight_smile:

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I live on a ranch and sometimes there is an emergency that means I cannot stop what I’m doing to go and get a snack but I don’t think it causes me any harm. If you are worried about exercising while low then stop exercising until your BG comes back up to normal. If it doesn’t come back up with fast acting carbs like glucose within 15 minutes then maybe consider packing it in for the day or maybe just a few hours.

Serious lows are way different in the way they affect your body than mild lows. For instance a serious low will have your body throwing everything at it that it can and will make you end up feeling sucky for hours but a mild low is something that happens to even the most healthy non-diabetic and I personally wouldn’t worry about any long term effect from it. If you regularly go low while exercising then I would keep glucose or “energy shots” with me to stop them so I could keep going if I needed to. For instance if I was training for a marathon or something, not that I ever have but you probably get my point.

Thanks for your reply and input, @Firenza. I´m not worried for myself, I was diagnosed in 1983 and has both a pump and a Dexcom, and none of my blood work today would even show that I´m a diabetic, so I´m not worried about me and my diabetes. I could easily just carry on at 45 mg/dl (2,5 mmol/L). I prefer not to, but I sometimes do even though my absolute low limit before considering it low is 65 (3,6 mmol/L). And for the record even though it´s not me we are talking about here,- I´ve not even once since 1983 needed help or used glucagon when having a low.

What I really wonder if it is any truth in what health care professionals says about this topic. I´v now heard from three different sources that is is harmful or if not directly harmful,- it´s not benefiting your health.

Is there any scientific truth in this? And if so, why is it harmful? How does it affect you?

I know Dr. Bernstein claims that just beeing a diabetic puts oxidative stress to uor body the same way it would if you were a professional athlete, and that you should treat your body the same way be replenishing vitamins and micronutrionts. I read it in his first book and do not remember exactly what he writes, but the only thing I can think of is that getting low and not stopping to get restituted will be something similiar to putting “oxidative stress” on your body.

Does anyone know anything about this? Or has some scientific input about how it works?

Dave I do the same and will take the wrath from my wife for doing so but I do push on and after eating and drinking carbs I’m ready to go within 45 minutes or so. Done so since being on insulin since 1969
Probably not right but it rules my life enough already.

I have absolutely no idea if exercising while low can do harm to a body, but there is one thing I am certain of, is that it is bad for your performance. When I run, I usually will do various type of running associated to different heart rate. For example at 120beat/min I usually run at about 11km/h, if I am low or getting low, my heart beats faster and does not come down as fast as it is suppose. Hence my body is not as efficient as it is while not on a low. I loose about 1,5km/h at the same heart rate. And, if I continue to ignore the low, I will feel tired and the run will be very unpleasant (it is hard for me to imagine some one running ignoring a low blood sugar, but then again, to each their own…).

You never say specifically what is causing these lows. If you’re type 1, it sounds like you need a doctor/ medical team who will work with you to get your medication and your physical fitness in sync.

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Thanks for your input and advice, @Villandra. I understand the concern when I write “I almost always ending up going low at one point or another in the course of a five hour excercise session of some kind.” I´m not worried about this or my situation, so if this could be about the topic I raise and not my private situation, I would really appreciate that. Does that sound fair?

Siri, my endocrinologist told me that lows are dangerous for the brain! The brain is normally dependent on glucose for oxidative metabolism and function. Acute “lows” can cause clinically significant cognitive impairment over the short AND long term. So I wouldn’t keep exercising until I took care of the low if by low you mean below 60-65!

If that were true for everyone I’d be a blithering idiot by now. I’ve had thousands upon thousands of lows. I get low nearly every day…since 1978. Lows in the 40’s and 50’s. Do the math. Some people DIE from lows, but others seem to manage. I was once near zero for a few minutes–THAT was awful. Having said all that I don’t recommend it. :slight_smile: I’m in the 50’s at the moment, BTW.

@ dave44

I don’t think you can make a general statement about the danger lows present based on your personal experience. I’ve had T1 since 1973 and in the days prior to continuous monitoring, have needed medical assistance twice (lost consciousness). In 2001 I was diagnosed with partial complex epilepsy, and while they can’t unequivocally prove it, my neurologist and endo believe recurring low blood sugars over an extended period may be at least partially responsible. I now have another chronic disease, have some restrictions on my activities, and will be taking anti-seizure medication the rest of my life.

Maybe your on one end of the ‘danger’ extreme and I’m at the other, but I don’t think it’s something anyone should treat casually. I would never wish what I’ve experienced on anyone.


I never said that lows can’t hurt someone else,. I already acknowledged that some people DIE from lows. My daughter-in law’s step-dad died in his sleep from a low, so no need to claim I’m making “general statements”. What I said was if it’s true for EVERYONE, I’d be a blithering idiot by now. See the distinction? I didn’t say that lows won’t affect others.

I was responding to this: _"Siri, my endocrinologist told me that lows are dangerous for the brain!"

I’ll say it again, it it was bad for EVERYONE, I’d be a blithering idiot by now.

I literally have been low way more than 10,000 times. That is NOT an exaggeration., It’s probably closer to 15,000.

Dave44, I’ve had Type 1 diabetes for 60 years! I also have heart disease. Besides lows not being good for the brain they are also very hard on the heart! I guess my point was don’t take “lows” lightly! They don’t do the body good! :slight_smile:

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