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What does research say about muscles, connective tissue and aging?


This article by Robert Umfress analyses and breaks down new research on fascia and connective tissue.



Skeletal muscle and aging


In most people, muscle loss begins in the third decade of life and progresses with age. Muscle fibers shift from stronger, less efficient type II to weaker, more efficient type I due to decreased physical demands. Comparing similar muscle volume, maximum voluntary contraction is lower in older populations, however the muscle fibers themselves don’t appear to differ in power with aging. This coupled with strength decreasing faster than muscle size suggests a neuromuscular component to aging.

The stiffness and tone of myofascial tissues increase while the elasticity of these tissues decreases with aging.


The good news is the capacity to adapt to stimulus is still there for aged populations. Muscle and connective tissue remodel with use in older populations, growing more efficient with exercise. However, when getting back to activity, the tissues of an aged individual might struggle more than their younger counterparts with building positive adaptations.



Connective tissue and aging


With aging comes a shift in the types of collagen produced, leading to a more rigid matrix and impairing the regenerative potential of the system. Aging also brings a decrease in water content in the tendon and connective tissue with a decrease in collagen content and thickness. Zooming out, fascia of the lower limbs most often decreases in thickness while fascia of the low back most often increases in thickness with age. These changes could contribute to decreased range of motion in the joints. Collagen degradation and remodeling decreases with age but it appears to be reversible with resistance training.






Coupling between fascia, skeletal muscle, and aging


Movement performance depends on the cooperation and status of both fascia and muscle. The changes in the connective tissue and muscles of aged populations alters the transmission of forces in all directions. Alteration of the myofascial structures can contribute to co-activation of antagonist muscles, which reduces range of motion in the joints.

 

The fluid component of the fascia helps with dissipating energy while the fiber component stores and releases elastic energy. Muscles in different areas of the body can synergize to work together through linking of fascial structures, contributing to proprioception and locomotion. These interactions appear to weaken with age, reducing the capacity for force transmission. Fascial tissue can densify or even develop fibrosis with age. These both reduce force production and range of motion. Decreased mobility could also be explained by increasing dehydration related stiffness in the extracellular matrix combined with increased collagen content.



Connective tissue, inflammation, aging


Aging tissue shows a low-grade chronic systemic inflammation without infection, termed “inflammaging.” Most of the inflammatory processes occur in the extracellular matrix of the fascial tissue, which might damage structural elements of the tissues and decrease tissue regeneration.

 

 

Motor System and Aging


Structural integrity of neuromuscular junctions is affected by aging, contributing to poor nerve signaling for movement tasks  and problems  with motor units. In some studies with mice, the negative effects of aging on the neuromuscular junction were reduced and even reversed with physical exercise.

 


Imaging and Ultrasound Methods


Although there have been many advances in recent years, there is still no gold standard imaging for looking at the contractile properties and myofascial tissues in the context of aging. There appears to be promise with ultrasound, but it isn’t quite there for this use case.

 


Manipulation Techniques and Fascia Repair


Studies support soft tissue techniques to relieve myofascial-induced pain and dysfunction. Treatment generally needs to stimulate nerve and fascia to be effective. Ultrasound, laser, massage, mobilisation, manipulation, traction, and needling can all relieve pain in injured athletes.  However, the effect of aging on the efficacy of these treatments is unclear. Little research has been done in this area with conflicting results. For now, the authors hypothesise that the tissue is susceptible to soft tissue stimuli but to what degree is yet to be determined.



For further information check out Robert Umfress review of the article: "Structural and Functional Changes in the Coupling of Fascial Tissue, Skeletal Muscle, and Nerves During Aging."



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