# Muscles are sore, why isn't my heart? **URL:** \ **Category:** Factual Questions\ **Created:** [March 19, 2003, 10:32pm UTC](https://boards.straightdope.com/t/muscles-are-sore-why-isnt-my-heart/162651 "2003-03-19T22:32:16Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![NurseCarmen](https://avatars.discourse-cdn.com/v4/letter/n/5daacb/32.png) [@NurseCarmen](https://boards.straightdope.com/u/NurseCarmen)\ **Post date:** [March 19, 2003, 10:32pm UTC](https://boards.straightdope.com/t/muscles-are-sore-why-isnt-my-heart/162651/1 "2003-03-19T22:32:16Z")
Why doesn’t my heart get sore after a nice bout of excercising? Heck, I’ve had days were various mucles felt bruised from the previous day’s workout. Why doesn’t my heart feel the same? It’s a muscle. Smooth muscle, yet a muscle. ---
**Author:** ![Speaker\_for\_the\_Dead](https://avatars.discourse-cdn.com/v4/letter/s/c77e96/32.png) [@Speaker\_for\_the\_Dead](https://boards.straightdope.com/u/Speaker_for_the_Dead)\ **Post date:** [March 19, 2003, 10:49pm UTC](https://boards.straightdope.com/t/muscles-are-sore-why-isnt-my-heart/162651/2 "2003-03-19T22:49:30Z")
Because it is made of smooth muscle, which is designed to do exactly what the heart does, and not get tired out, while our arms (for example) are made of striated[sic] muscle, which is designed for more power over a much shorter period of time, and can get tired out, as you have pointed out. ---
**Author:** ![Qadgop\_the\_Mercotan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/qadgop_the_mercotan/32/83_2.png) [@Qadgop\_the\_Mercotan](https://boards.straightdope.com/u/Qadgop_the_Mercotan)\ **Post date:** [March 19, 2003, 11:36pm UTC](https://boards.straightdope.com/t/muscles-are-sore-why-isnt-my-heart/162651/3 "2003-03-19T23:36:42Z")
Sorry **speaker** and **nursecarmen** , but that’s not quite right. Cardiac muscle has features of both smooth and skeletal muscle, and is uniquely different from either of them. Its chief function is to beat, regularly and reliably and rhythmically, without fail. Unlike skeletal muscle, it stays neither relaxed nor contracted for excessive amounts of time, which is where one generally gets muscle inflammation from; periods of inactivity combined from periods of overuse. The cardiac muscle can become inflamed, however. This is generally due to a disease state rather than just a strenuous workout. Heavy-duty exercise will raise the rate, but the _healthy_ heart has an automatic nervous system feedback loop to keep it from going so fast it can’t pump effectively or relax properly between contractions. Here’s a nice site about cardiac muscle: [http://www.umds.ac.uk/physiology/rbm/cmusc.htm](http://www.umds.ac.uk/physiology/rbm/cmusc.htm) ---
**Author:** ![FabioClone](https://avatars.discourse-cdn.com/v4/letter/f/5f8ce5/32.png) [@FabioClone](https://boards.straightdope.com/u/FabioClone)\ **Post date:** [March 19, 2003, 11:49pm UTC](https://boards.straightdope.com/t/muscles-are-sore-why-isnt-my-heart/162651/4 "2003-03-19T23:49:00Z")
The soreness is usually caused by lactic acid buildup when the cells are forced into anaerobic respiration(without oxygen). As for why this does not occur in the heart… well I’m sure somebody else could answer that question better than I. I would guess that either the heart tissue is kept well-oxygenated or the heart contractions are not sufficient to overwork the tissue (like **Qadgop the Mercotan** said). ---
**Author:** ![barbitu8](https://avatars.discourse-cdn.com/v4/letter/b/839c29/32.png) [@barbitu8](https://boards.straightdope.com/u/barbitu8)\ **Post date:** [March 20, 2003, 1:20am UTC](https://boards.straightdope.com/t/muscles-are-sore-why-isnt-my-heart/162651/5 "2003-03-20T01:20:52Z")
> [@](#): > > \*Originally posted by FabioClone \* > \*\*The soreness is usually caused by lactic acid buildup when the cells are forced into anaerobic respiration(without oxygen). \*\* This is false. The soreness (DOMS: delayed-onset muscle soreness) is caused by microtrauma to the muscle fibers, which does not occur in the cardiac muscle fibers. Lactic acid is quickly dissipated in the body, through the liver and conversion back into glucose. DOMS, as the name states, has a delayed onset. You don’t get sore until the next day. By then the lactic acid is all gone. ---
**Author:** ![FabioClone](https://avatars.discourse-cdn.com/v4/letter/f/5f8ce5/32.png) [@FabioClone](https://boards.straightdope.com/u/FabioClone)\ **Post date:** [March 20, 2003, 1:28am UTC](https://boards.straightdope.com/t/muscles-are-sore-why-isnt-my-heart/162651/6 "2003-03-20T01:28:00Z")
> [@](#): > > This is false. The soreness (DOMS: delayed-onset muscle soreness) is caused by microtrauma to the muscle fibers, which does not occur in the cardiac muscle fibers. You mean they lied to me in biology class? Or is this a new finding? ---
**Author:** ![lorinada](https://avatars.discourse-cdn.com/v4/letter/l/b5e925/32.png) [@lorinada](https://boards.straightdope.com/u/lorinada)\ **Post date:** [March 20, 2003, 1:36am UTC](https://boards.straightdope.com/t/muscles-are-sore-why-isnt-my-heart/162651/7 "2003-03-20T01:36:07Z")
While lactic acid has been disproved, the “microtears” is still just a theory. There as yet is still no proven cause of DOMS. [http://www.frsa.com/doms.html](http://www.frsa.com/doms.html) Sorry, my puter is screwing up and this is the only site I could pull up before it started crapping out. ---
**Author:** ![Qadgop\_the\_Mercotan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/qadgop_the_mercotan/32/83_2.png) [@Qadgop\_the\_Mercotan](https://boards.straightdope.com/u/Qadgop_the_Mercotan)\ **Post date:** [March 20, 2003, 1:37am UTC](https://boards.straightdope.com/t/muscles-are-sore-why-isnt-my-heart/162651/8 "2003-03-20T01:37:20Z")
Well, it’s a little of this and a little of that. Microtrauma causes the muscle pain. But most microtrauma is not the result of lactic acidosis, just excessive use, especially in deconditioned or poorly warmed up muscles. However, if lactic acidosis does occur, it will generally cause the muscle fibers to go into spasm, which will also cause not only immediate pain, but also microtrauma, and subsequent muscle soreness the next day, as inflammation sets in. So: If you exercise so hard you cramp up, you’re going into lactic acidosis, will suffer microtrauma, and will have inflamed muscles the next day. If you exercise hard but don’t cramp up, you’ll still have microtrauma, and will still have inflamed muscles the next day. But it probably won’t be as bad, if you managed to avoid muscle spasm. ---
**Author:** ![FabioClone](https://avatars.discourse-cdn.com/v4/letter/f/5f8ce5/32.png) [@FabioClone](https://boards.straightdope.com/u/FabioClone)\ **Post date:** [March 20, 2003, 1:56am UTC](https://boards.straightdope.com/t/muscles-are-sore-why-isnt-my-heart/162651/9 "2003-03-20T01:56:09Z")
Well, I’ve been looking around at some recent information and it looks like everything I knew about lactic acid was wrong. I took a human biology course only two years ago and learned that lactic acid was a waste product that accumulates in muscle tissue undergoing anaerobic respiration. As people have kindly pointed out, we now know that this is all a bunch of hooey. It looks like -Lactic acid is NOT a waste product. It can be produced in tissues that are well-oxygenated and can, in fact, be used as an energy source. -Lactic acid buildup may be responsible for initial muscle fatigue, but it is eliminated from the body rapidly. Therfore, it is probably not responsible for next-day soreness. Cool stuff. Thanks for pointing out my error. ---
**Author:** ![Hermann\_Cheruscan](https://avatars.discourse-cdn.com/v4/letter/h/b782af/32.png) [@Hermann\_Cheruscan](https://boards.straightdope.com/u/Hermann_Cheruscan)\ **Post date:** [March 20, 2003, 3:33am UTC](https://boards.straightdope.com/t/muscles-are-sore-why-isnt-my-heart/162651/10 "2003-03-20T03:33:15Z")
A slight hijack: Is it true that the lowering of the weight is much more likely to cause muscle soreness than the raising of the weight? ---
**Author:** ![barbitu8](https://avatars.discourse-cdn.com/v4/letter/b/839c29/32.png) [@barbitu8](https://boards.straightdope.com/u/barbitu8)\ **Post date:** [March 20, 2003, 9:49pm UTC](https://boards.straightdope.com/t/muscles-are-sore-why-isnt-my-heart/162651/11 "2003-03-20T21:49:32Z")
[Dr. Mirkin](http://www.drmirkin.com/fitness/1346.html) states that muscle tears causes DOMS and gives studies indicating this. I read somewhere, but cannot put my finger where, that the eccentric (lowering) is the main factor in DOMS. ---
**Author:** ![troub](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/troub/32/14802_2.png) [@troub](https://boards.straightdope.com/u/troub)\ **Post date:** [March 20, 2003, 9:57pm UTC](https://boards.straightdope.com/t/muscles-are-sore-why-isnt-my-heart/162651/12 "2003-03-20T21:57:52Z")
All of my high school biology classes drilled the soreness==lactic acid buildup into me also. I don’t remember what they said about it in my college physiology class (3-4 yrs. ago), but I don’t remember hearing _anything_ about microtrauma before. Ahhh, I should tell my boss that “wasting” a few minutes here and there on the internet is a source of continuing education! 😃 ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [March 20, 2003, 11:30pm UTC](https://boards.straightdope.com/t/muscles-are-sore-why-isnt-my-heart/162651/13 "2003-03-20T23:30:14Z")
I have heard, though, that even a few days of allowing the heart to rest (by means of an artificial pump) looks extremely promising, and may add years or decades to the life of a person with heart troubles. Anyone else heard anything about this? ---
**Author:** ![mmmiiikkkeee](https://avatars.discourse-cdn.com/v4/letter/m/edb3f5/32.png) [@mmmiiikkkeee](https://boards.straightdope.com/u/mmmiiikkkeee)\ **Post date:** [March 21, 2003, 8:51am UTC](https://boards.straightdope.com/t/muscles-are-sore-why-isnt-my-heart/162651/14 "2003-03-21T08:51:30Z")
I don’t remember anyone in biology classes saying lactic acid causes soreness the next day; I’ve always heard it caused the immediate pain when you are really straining hard; like the soreness in your thighs after running up 100 stairs - which goes away within a few seconds after you stop… hmmm, is the speed at which the buring in a working muscle disappears proportional to the rate at which lactic acid is metabolized? - that would be pretty fast! Actually, that’s kind of a highjack, so no need to answer. ---
**Author:** ![Tal](https://avatars.discourse-cdn.com/v4/letter/t/54ee81/32.png) [@Tal](https://boards.straightdope.com/u/Tal)\ **Post date:** [March 21, 2003, 11:58am UTC](https://boards.straightdope.com/t/muscles-are-sore-why-isnt-my-heart/162651/15 "2003-03-21T11:58:31Z")
> [@](#): > > Dr. Mirkin states that muscle tears causes DOMS and gives studies indicating this. Dr Mirkin is a scary person! He has some info on his website that is just so far out wrong that it’d dangerous…seriously, I know of people who’ve mass contacted him on one particular issue…he eventaully confessed and changed SOME of the info…but seriuosly, don’t trust anythign he says - it’s dangerous ---
**Author:** ![johncole](https://avatars.discourse-cdn.com/v4/letter/j/5f9b8f/32.png) [@johncole](https://boards.straightdope.com/u/johncole)\ **Post date:** [March 21, 2003, 1:09pm UTC](https://boards.straightdope.com/t/muscles-are-sore-why-isnt-my-heart/162651/16 "2003-03-21T13:09:53Z")
> [@](#): > > \*Originally posted by Chronos \* > \*\*I have heard, though, that even a few days of allowing the heart to rest (by means of an artificial pump) looks extremely promising, and may add years or decades to the life of a person with heart troubles. Anyone else heard anything about this? \*\* Yes indeed. Artificial _assists_ are being used both as a “bridge to transplant” (keeps you going until a donor becomes available) and as a “bridge to recovery” (when the resident heart recovers all or part of its function after a period of rest) both in the US and in Europe. more [here](http://www.chron.com/content/chronicle/metropolitan/heart/lvad.2-0.html#axial) and [here](http://www.fda.gov/bbs/topics/answers/ANS00447.html). > [@](#): > > FDA recently approved for marketing the first heart-assist device for use in patients who experience heart failure after heart surgery and do not respond to conventional post-operative treatment with drugs or intra-aortic balloon pumps to re-establish circulation. By pumping blood through the body, the newly-approved device lets the heart rest so it can recover and resume its normal function. ---
**Author:** ![PhuQan\_G\_Nyus](https://avatars.discourse-cdn.com/v4/letter/p/f14d63/32.png) [@PhuQan\_G\_Nyus](https://boards.straightdope.com/u/PhuQan_G_Nyus)\ **Post date:** [March 21, 2003, 1:23pm UTC](https://boards.straightdope.com/t/muscles-are-sore-why-isnt-my-heart/162651/17 "2003-03-21T13:23:09Z")
One thing overlooked here is that the heart does not have pain receptors itself. During a heart attack pain comes from lots of other sources including the pericardium (which surrounds the heart). ---
**Author:** ![barbitu8](https://avatars.discourse-cdn.com/v4/letter/b/839c29/32.png) [@barbitu8](https://boards.straightdope.com/u/barbitu8)\ **Post date:** [March 21, 2003, 7:05pm UTC](https://boards.straightdope.com/t/muscles-are-sore-why-isnt-my-heart/162651/18 "2003-03-21T19:05:03Z")
> [@](#): > > \*Originally posted by Tal \* > \*\*Dr Mirkin is a scary person! He has some info on his website that is just so far out wrong that it’d dangerous…seriously, I know of people who’ve mass contacted him on one particular issue…he eventaully confessed and changed SOME of the info…but seriuosly, don’t trust anythign he says - it’s dangerous \*\* He’s not the only one who asserts that DOMS is caused by muscle tears, and he gave studies documenting that theory. I think it’s libel to say not to trust anything he says. You mention one issue and say that he changed it somewhat, but you don’t say what the issue was, what he said, and how he changed it. No matter. He may have made a slight error, but who hasn’t? I find him very reliable. ---
**Author:** ![David\_Simmons](https://avatars.discourse-cdn.com/v4/letter/d/9de053/32.png) [@David\_Simmons](https://boards.straightdope.com/u/David_Simmons)\ **Post date:** [March 22, 2003, 5:23am UTC](https://boards.straightdope.com/t/muscles-are-sore-why-isnt-my-heart/162651/19 "2003-03-22T05:23:17Z")
> [@](#): > > \*Originally posted by FabioClone \* > \*\*Well, I’ve been looking around at some recent information and it looks like everything I knew about lactic acid was wrong. \*\* Ain’t it a bitch? Unless you keep up with all the latest publications and attend all the symposia in your field, pretty much everything you know is out of date, if not just plain wrong. Isaac Asimov wrote an amusing article entitled _The Sound of Panting_ that detailed the extreme difficulty of staying current in your own field without even trying to keep up with related studies. ---
**Author:** ![CanvasShoes](https://avatars.discourse-cdn.com/v4/letter/c/74df32/32.png) [@CanvasShoes](https://boards.straightdope.com/u/CanvasShoes)\ **Post date:** [March 22, 2003, 5:44am UTC](https://boards.straightdope.com/t/muscles-are-sore-why-isnt-my-heart/162651/20 "2003-03-22T05:44:44Z")
Hope you guys don’t knock me over the head for stating the obvious here. All the lactic acid buildup vs. micro tears is interesting but, to me the answer to "why your heart doesn’t get sore is kind of obvious. The heart isn’t undergoing any more weight bearing exercise during weight LIFTING than it does during cardio exercise, or mere day to day beating to keep us alive. If you could somehow make your heart do “bicep curls” or force it to be the muscle hiking up those stairs, maybe you would then feel “the burn”. As it is, during weight training, your heart is just doing it’s job, same as always, it speeds up and pumps more blood to aide your workout, just like it would for the stairmaster, or for a happy night of romance with your SO :). [Next page](https://boards.straightdope.com/t/muscles-are-sore-why-isnt-my-heart/162651.md?page=2)