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Recently I've got into the argument which involved muscle growth, muscle pain, DOMS and lactic acid. I tried serfing web, but it's hardly trustworthy source of information (to be precise it's REALLY hard to find reasanoble explanation).

I've got several questions which I'd like to find answers to.

  • How do muscles grow?
  • How long does it take for lactic acid to clear out of muscles?
  • Something about DOMS

So the question is where can I find the real scientific explanation for these kinds of questions? Are there any usefull publications or maybe some litreture?

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  • Something about DOMS? – John Feb 20 '17 at 12:53
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  1. How do muscles grow?

Muscle hypertrophy involves an increase in size of skeletal muscle through a growth in size of its component cells. Two factors contribute to hypertrophy: sarcoplasmic hypertrophy, which focuses more on increased muscle glycogen storage; and myofibrillar hypertrophy, which focuses more on increased myofibril size

Baechle, Thomas R.; Earle, Roger W., eds. (2008). Essentials of strength training and conditioning (3rd ed.). Champaign, IL: Human Kinetics. ISBN 978-0-7360-5803-2.

Note that: Microtrauma, which is tiny damage to the fibers, may play a significant role in muscle growth.

Resistance training leads to trauma or injury of the cellular proteins in muscle. This prompts cell-signaling messages to activate satellite cells to begin a cascade of events leading to muscle repair and growth. Several growth factors are involved that regulate the mechanisms of change in protein number and size within the muscle.

Chargé SB, Rudnicki MA (2004). "Cellular and molecular regulation of muscle regeneration". Physiol. Rev. 84 (1): 209–38. doi:10.1152/physrev.00019.2003. PMID 14715915. Lay summary – Len Kravitz

  1. How long does it take for lactic acid to clear out of muscles?

Depends on a lot of personal factors and can vary wildly. There are some myths on lactic acid that are explained well by this article.

  1. Lactic acid is not responsible for delayed onset muscle soreness.
  2. Lactic acid is not responsible for muscle cramping.
  3. Lactic acid is not responsible for muscular acidosis (aka "the burn" during exercise within muscles). Thus, lactic acidosis is a misnomer and false.
  4. Lactic acid is not responsible for muscle fatigue.
  5. Lactic acid can be used a semi-fuel source by some tissues such as the heart, brain, and type I muscle fibers, as well as remade into glucose in the liver through the Cori cycle.

"The Truth about Lactic Acid". Steven Low (2016). http://stevenlow.org/the-truth-about-lactic-acid/ accessed: 20/2/16

This was posted on reddit and the most commented answer may be of some relevance:

If lactic acid doesn't contribute to muscle fatigue, why does the lactate threshold matter for performance?

Because lactic acid build-up is a sign that anaerobic metabolism is becoming more dominant, and other factors associated with anaerobic metabolism lead to fatigue.

Unknown User, Reddit

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  • Thanks for your answer! The thing is I'm trying to explain these things to my mother, who graduated from medical university. She remembers really well things she was taught. And these are her main argument - her knowledge and medical books from USSR. And Internet resources don't convince her much (cause obviously people writing articles don't have medical degree). As for DOMS I encountered the articles stating that there are just hypothesis about sources of delayed onset muscle sorness. So I was wondering if there is some other litreture about it. – Fal Alexandr Feb 22 '17 at 2:45
  • There is literature but a lot of it is conflicting as its still not well understood. Leading theories suggest it is the bodies protective reaction due to the sudden micro trauma of large sections of muscle. – John Feb 22 '17 at 7:50

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