The importance of the musculoskeletal system is recognised by almost everyone, be they laypeople, enthusiasts, exercise professionals or scientists. Everyone's understanding of its properties will certainly be different. The traditional view focuses on the visible attribute, i.e. the importance of its mechanical properties, and how these are responsible for the expression of strength. Undoubtedly, the richness of human movement, with the mobilisation and stabilisation of segments and axes, is only possible because of this driving force. However, we know that it fulfils functions far beyond muscle contraction.
The musculoskeletal system is a crucial element in the interaction with the central nervous system, metabolism and hormonal regulation. This short opinion piece aims to explore some of these attributes and functions, as well as the impact that the musculoskeleton can have on optimising various physiological systems and general health.
The Muscle as a Sensory Extension of the Central Nervous System
The functions of the musculoskeletal system go beyond the mere execution of motor commands; it is also a complex sensory system. Its structure includes muscle spindles and Golgi tendon organs, structures that act as sensors and respond to mechanical stimuli, transmitting information about muscle position and tension to the central nervous system. It is in this relationship that modulation and refined regulation of muscle tone takes place, preventing injuries and guaranteeing precise movements. With this information we can already speculate that movements that are too wide or tensions that exceed the tolerance threshold of this system can compromise structure, weaken function and increase the risk of injury in the short, medium and long term.
In addition, there is robust evidence of the influence that muscle has on neural plasticity, contributing to both motor and cognitive learning, as well as neuroprotection against degenerative diseases such as Alzheimer's and Parkinson's. Regular physical activity and exercise have been associated with an improvement in cognitive function and neuroplasticity through the release of neurotrophic factors such as BDNF (Brain-Derived Neurotrophic Factor)(1,2). It should also be noted that the benefits increase in proportion to duration, at least in the segregation of BDNF. Are we making time to be more active?
Muscle as a Metabolic and Endocrine Regulator
Beyond the mechanical aspects of muscle... Skeletal muscles play a vital role in metabolic homeostasis. They are responsible for approximately 80 per cent of insulin-induced glucose uptake (3) and are essential in the prevention and treatment of metabolic diseases such as type 2 diabetes. It is interesting to note that muscle contraction, regardless of the presence of insulin, is capable of activating glucose transport mechanisms inside the cell, making physical exercise a powerful therapeutic tool, whether in pathology, prevention or simply metabolic optimisation.
In addition, muscle releases metabolically active substances that are capable of influencing various tissues and organs (4). These signalling molecules are known as myokines and have been studied for their importance in tissue regeneration, immune regulation and energy homeostasis. More recently they have been given another name, exertins, because they are directly and specifically related to physical exercise (5).
Systemic impact on the musculoskeletal system
1. Influence on cardiovascular health. Muscle contraction promotes vasodilation and improves endothelial function, reducing arterial stiffness and contributing to blood pressure regulation. Resistance training on ergometers (e.g. bicycle, treadmill) secretes vasodilator substances, which has a protective effect and contributes to reducing cardiovascular risk.
2. Role in bone homeostasis. For the muscle to contract, it needs attachment points - these points are in the bones. Muscle contraction is therefore able to impose mechanical stress on the bone, which in turn stimulates bone remodelling. It should also be noted that this process involves the release of osteocalcin, a protein associated with bone metabolism, which seems to be involved in regulating energy metabolism.
3. Modulation of the immune system. Moderate exercise also has an anti-inflammatory effect, reducing levels of pro-inflammatory cytokines and increasing the efficiency of the immune system. It should be noted that the muscle acts directly in regulating immunity, contributing to this with the substances produced as a result of its metabolism - muscle metabolites.
Conclusion
I think it's clear that the musculoskeletal system is much more than just a contractile element responsible for movement. Its interaction with the central nervous system, its endocrine function and the influence it exerts on various physiological systems express its importance in maintaining health and longevity. Recognising these interactions reinforces the importance of regular and conscious physical exercise. Only in this way can muscle function be individualised and optimised with a view to promoting the health, well-being and quality of life that everyone deserves.
Eduardo André
Exercise Physiologist
Want to know more about this topic? Sign up for the Muscle and Longevity lecture on 1 March at 4pm.
Stillman, C. M., Cohen, J., Lehman, M. E., & Erickson, K. I. (2020). Mediators of physical activity on neurocognitive function: A review at multiple levels of analysis. Frontiers in Human Neuroscience, 14, 62. https://doi.org/10.3389/fnhum.2020.00062
Dinoff, A., Herrmann, N., Swardfager, W., & Lanctôt, K. L. (2021). The effect of acute exercise on blood concentrations of brain-derived neurotrophic factor in healthy adults: A meta-analysis. European Journal of Neuroscience, 53(3), 637-651. https://doi.org/10.1111/ejn.15088
Hayashi, T., Wojtaszewski, J. F., & Goodyear, L. J. (2000). Exercise regulation of glucose transport in skeletal muscle. American Journal of Physiology-Endocrinology and Metabolism, 278(6), E1020-E1035. https://doi.org/10.1152/ajpendo.2000.278.6.E1020
Pedersen, B. K., & Febbraio, M. A. (2012). Muscles, exercise and obesity: Skeletal muscle as a secretory organ. Nature Reviews Endocrinology, 8(8), 457-465. Esta revisão destaca o papel do músculo esquelético como um órgão secretor, enfatizando a liberação de miocinas durante a contração muscular e seus efeitos na homeostase energética e na regulação imunológica.
Chow, L. S., Gerszten, R. E., Taylor, J. M., et al. (2022). Exerkines in health, resilience and disease. Nature Reviews Endocrinology, 18, 273–289. https://doi.org/10.1038/s41574-022-00641-2
Comments