Muscle maintenance: Avoid (and repair) damage
Whether your Saturday includes a morning pickup basketball game or a total overhaul of the landscaping in your yard, over-doing it on the weekend can leave you limping back to work on Monday.
Your body is comprised of over 600 muscles. Each one is made of small fibres that are about 40 millimetres long. Muscle strength is determined by the number of muscle fibres present. There are three types of muscle tissue: skeletal muscle, cardiac muscle (heart and circulation), and smooth muscle (digestive tract, etc). This article will focus on skeletal muscle.
As you might expect, skeletal muscle is attached to the skeleton, and these muscles make up approximately 40% of your body weight. The reason you can move your skeleton is because of the way your muscles act on your bones. Skeletal muscle mass peaks in your twenties, and gradually decreases over time, with noticeable loss starting in your forties.
We want to support the growth and regeneration of muscle, and the only way to do that is to use them. When you put your muscles through intense exercise – either at the gym or landscaping the yard – you cause micro-trauma or injury to muscle fibres.
This injury activates satellite cells, which are stem cells that are located outside of muscle fibres. These cells typically lay dormant until they are called upon to promote muscle repair. More on the satellite cells later.
How hormones impact muscle
Resistance exercise stimulates the release of growth hormone from the pituitary gland, with released levels being very dependent on exercise intensity. Growth hormone helps to trigger fat metabolism for energy use in the muscle growth process and stimulates the uptake and incorporation of amino acids into protein in skeletal muscle. 
The hormone insulin also stimulates muscle growth by enhancing protein creation and easing glucose entry into cells, including those satellite cells mentioned above. Testosterone enhances cellular amino acid uptake and protein synthesis in skeletal muscle. In addition, testosterone can activate tissue growth and may have a regulatory effect on satellite cells. (2) Men especially want to support healthy testosterone.
While micro-injury is good, too much is a problem. Muscle damage can occur from a crush injury or from over-doing it at the pick-up game or hauling dirt around your yard. Damage involves compromised architecture in muscle fibre and can cause inflammation and pain. Injury also disrupts protein integrity and causes dysfunction in cell mitochondria. Mitochondria are important because they generate most of the energy required to power the cell.
Repair begins with satellite cells fusing together and to the damaged muscles fibres. After fusion with the muscle fiber, some satellite cells serve as a source of new nuclei to supplement the growing muscle fiber. With these additional nuclei, the muscle fiber can make more proteins. This often leads to increase in “muscle size.”
How can you help?
Don’t ‘save it all’ for the weekend! Rather than going from zero activity Monday through Friday to full-exertion on the weekend, make a habit of moving every day of the week. Movement can be as simple as stretching before you head into the shower, doing squats and push-ups between zoom calls, or walking around the block on your lunch break.
Adding in some sport- or activity- specific conditioning can help you stay ready for whatever the weekend brings. Research also shows that sleep is necessary to support repair of muscle injury, so be sure you commit to rest at the end of the day.
Feed your muscles
Muscles, bones and your immune system require protein. Any excess amino acids are stored in muscle but if you don’t eat enough of it, amino acids stores are pillaged to meet needs elsewhere. Over time, this can lead to muscle loss.
Aim for a minimum of .8 grams of protein per kilogram (or .36 grams of protein per pound) of body weight. Note that your age and activity level impact this minimum and you may require more. If in doubt, add supplemental protein powder to your health routine.
Vitamin D is an essential nutrient for the skeletal muscle throughout your life. Increasing evidence shows that vitamin D may play an important role during muscle damage and regeneration by improving cellular turnover. Vitamin D also seems to regulate the activity of satellite cells that instigate repair, perhaps by altering mitochondrial density or function. (1)
Brain and braun
With a name like “brain derived neutrophin factor” (BDNF), you likely wouldn’t be surprised that this myokine is important for your brain and nervous system. However, BDNF receptors are also found in skeletal muscles. Significantly, BDNF is expressed by muscle satellite cells and this process is amplified when muscle is injured. Research suggests that BDNF might play an important role in supporting the satellite cell response to muscle injury.
In other words, you want to amp up your BDNF. Fortunately, BDNF levels in the brain, blood and muscles increase in response to exercise. Some research indicates, in fact, that BDNF might be the link between exercise and improved brain function.
Mushrooms for muscle health
Research has shown that compounds from from the fruiting bodies of lion’s mane mushrooms increase BDNF. Although there are yet any published studies on the impact of lion’s mane in muscle recovery, it has been shown to play a role in repairing nerve damage. Stay tuned for more studies!
Because any type of injury causes “stress” in your body, you can also turn to the adaptogenic properties of reishi to help your body cope with muscle damage. Animal research suggests that reishi may not only slow down the loss of muscle mass associated with stress, but also stimulate the formation of muscular tissue.
Muscle health is critical for strength, but it also plays a role in metabolism. Whether you are a weekend warrior or demand a lot from your body daily, give your muscles the attention they deserve.
Lisa Petty, PhD is Education Manager at Optimi. Learn more about her interests and background here.
 Latham, C. M., Brightwell, C. R., Keeble, A. R., Munson, B. D., Thomas, N. T., Zagzoog, A. M., … Fry, J. L. (2021). Vitamin D Promotes Skeletal Muscle Regeneration and Mitochondrial Health. Frontiers in Physiology, 12, 660498–660498. https://doi.org/10.3389/fphys.2021.660498
 Charge, S. B. P., and Rudnicki, M.A. (2004). Cellular and molecular regulation of muscle regeneration. Physiological Reviews, Volume 84, 209-238.
 Clow C, Jasmin BJ. Brain-derived neurotrophic factor regulates satellite cell differentiation and skeletal muscle regeneration. Mol Biol Cell. 2010 Jul 1;21(13):2182-90. doi: 10.1091/mbc.e10-02-0154. Epub 2010 Apr 28. PMID: 20427568; PMCID: PMC2893983
 Omura, T., Sano, M., Omura, K., Hasegawa, T., Doi, M., Sawada, T., and Nagano, A. (2005). Different expressions of BDNF, NT3, and NT4 in muscle and nerve after various types of peripheral nerve injuries. J. Peripheral Nerv. Syst. 10, 293–300. doi: 10.1111/j.1085-9489.2005.10307.x
 Yu, T., Chang, Y., Gao, X. L., Li, H., & Zhao, P. (2017). Dynamic Expression and the Role of BDNF in Exercise-induced Skeletal Muscle Regeneration. International Journal of Sports Medicine, 38(13), 959–966. https://doi.org/10.1055/s-0043-118343
 Ryu, S. H., Hong, S. M., Khan, Z., Lee, S. K., Vishwanath, M., Turk, A., … Lee, M. K. (2021). Neurotrophic isoindolinones from the fruiting bodies of Hericium erinaceus. Bioorganic & Medicinal Chemistry Letters, 31, 127714–127714. https://doi.org/10.1016/j.bmcl.2020.127714
 Wong, K-H., Naidu, M., David, RP., Abdulla, MA., & Kuppusamy, UR. (2009). Functional Recovery Enhancement Following Injury to Rodent Peroneal Nerve by Lion's Mane Mushroom, Hericium erinaceus. International Journal of Medicinal Mushrooms, 11,3, 225-236 doi: 10.1615/IntJMedMushr.v11.i3.20
 Bhardwaj, A., Sharma, P., Mishra, & J., Misra, K. (2019) Lingzhi or Reishi Medicinal Mushroom, Ganoderma lucidum (Agaricomycetes), Mycelium Aqueous Extract Modulates High-Altitude–Induced Stress. 21, 5, 2019, pp. 443-458. Doi: 10.1615/IntJMedMushrooms.2019030648
 Jatwani, A., & Tulsawani, R. Ganoderma lucidum induces myogenesis markers to avert damage to skeletal muscles in rats exposed to hypobaric hypoxia. High Alt Med Biol. 16:000–000, 2021.