Skeletal muscle, often viewed primarily in the context of exercise, actually plays a crucial role in overall health and longevity. Comprising 40% of body mass, this complex organ system not only facilitates movement but also acts as a metabolic hub. It manages glucose disposal, burns free fatty acids, and significantly influences insulin action, crucial for regulating blood glucose levels.
The repercussions of unhealthy skeletal muscle are substantial. When it struggles to handle food-derived substrates efficiently, issues such as insulin resistance and metabolic dysfunction emerge, impacting not just appearance but overall health. More concerning than gaining body fat is the loss of skeletal muscle, which precedes conditions like inflammation, obesity, and metabolic disorders, highlighting its role as the body's defence against aging-related catabolic crises. 1
As we age, the resilience of muscle health diminishes, making recovery from catabolic events less efficient. Skeletal muscle, functioning as an endocrine organ, releases myokines like interleukin-6 during contraction, playing a pivotal role in reducing inflammation and promoting overall health, especially in the brain. 2
Exercise is key to maintaining healthy skeletal muscle. It swiftly impacts triglycerides and HDL levels influences metabolic health and enhances mitochondrial efficiency. In a sedentary lifestyle with overeating, skeletal muscle faces challenges in managing substrates, potentially leading to insulin resistance and other health issues. 3
The importance of protein in supporting skeletal muscle health is undeniable. High-quality studies suggest an optimal intake of 0.7 to 1 gram of protein per half of a kilogram of ideal body weight, essential for preserving muscle through aging and improving body composition.4 Protein isn't a generic nutrient but is comprised of distinct amino acids, with nine essential ones that must be obtained from the diet. These amino acids play critical roles in muscle protein synthesis and supporting bodily functions like mucin, dopamine, and serotonin production. 5,6
Protein intake is indispensable for more than just preserving skeletal muscle health—it's a linchpin for various physiological functions within the body. Serving as the fundamental building blocks of life, proteins intricately engage in an array of bodily processes. Enzymes, vital catalysts, depend on proteins to instigate chemical reactions imperative for digestion, metabolism, and energy production. Additionally, many hormones crucial for regulating growth, metabolism, and mood are either proteins themselves or are synthesised using proteins. Notably, proteins contribute to fortifying the immune system, with antibodies, essential defenders against infections, being a product of protein. Moreover, proteins play a role in transporting molecules, like oxygen via haemoglobin, and in the storage of substances such as iron within ferritin. Their significance transcends mere muscular health; proteins are integral in constructing and mending various tissues, encompassing not only muscles but also skin, organs, and bones. Further, proteins contribute to maintaining fluid balance and act as buffers to regulate the body's pH, which is imperative for normal cellular function. Even the chemical messengers in the brain, neurotransmitters, frequently derive from amino acids—the elemental constituents of proteins. Thus, while protein remains vital for sustaining skeletal muscle health, its multi-faceted importance in supporting an array of bodily functions underscores the necessity of balanced protein intake for overall health and well-being. 7
Eating a lower protein diet compromises the body's ability to prioritise essential functions, potentially impacting overall health and bodily integrity. Prioritising adequate protein intake is vital for maintaining skeletal muscle health and various essential physical processes.
Recognising skeletal muscle's significance as a vital sign of overall health is crucial. Prioritising health beyond just exercise is fundamental in promoting longevity and combating a spectrum of metabolic diseases.
References
1. Merz KE, Thurmond DC. Role of Skeletal Muscle in Insulin Resistance and Glucose Uptake. Compr Physiol. 2020 Jul 8;10(3):785-809. doi: 10.1002/cphy.c190029. PMID: 32940941; PMCID: PMC8074531.
2. Hoffmann C, Weigert C. Skeletal Muscle as an Endocrine Organ: The Role of Myokines in Exercise Adaptations. Cold Spring Harb Perspect Med. 2017 Nov 1;7(11):a029793. doi: 10.1101/cshperspect.a029793. PMID: 28389517; PMCID: PMC5666622.
3. Pinckard K, Baskin KK, Stanford KI. Effects of Exercise to Improve Cardiovascular Health. Front Cardiovasc Med. 2019 Jun 4;6:69. doi: 10.3389/fcvm.2019.00069. PMID: 31214598; PMCID: PMC6557987.
4. Stuart M. Phillips & Luc J.C. Van Loon (2011) Dietary protein for athletes: From requirements to optimum adaptation, Journal of Sports Sciences, 29:sup1, S29-S38, DOI: 10.1080/02640414.2011.619204
5. Church DD, Hirsch KR, Park S, Kim IY, Gwin JA, Pasiakos SM, Wolfe RR, Ferrando AA. Essential Amino Acids and Protein Synthesis: Insights into Maximizing the Muscle and Whole-Body Response to Feeding. Nutrients. 2020 Dec 2;12(12):3717. doi: 10.3390/nu12123717. PMID: 33276485; PMCID: PMC7760188.
6. Dalangin R, Kim A, Campbell RE. The Role of Amino Acids in Neurotransmission and Fluorescent Tools for Their Detection. Int J Mol Sci. 2020 Aug 27;21(17):6197. doi: 10.3390/ijms21176197. PMID: 32867295; PMCID: PMC7503967.
7. Jiang, L., Wang, M., Lin, S., Jian, R., Li, X., Chan, J., ... & Doherty, J. A. (2020). A quantitative proteome map of the human body. Cell, 183(1), 269-283.
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