Clinical Pilates in Practice: Biomechanics & The Formation of Nervous Tissue

This review is a critical assessment of recent advances in the utilization of mechanical stimuli towards exploiting nervous tissue growth and formation. The authors discuss current in vitro systems designed to restate the mechanical environment of developing neural tissues, and the advancements made in integrating these systems into the clinical setting.

Pfister, Bryan J., Jonathan M. Grasman, and Joseph R. Loverde. "Exploiting biomechanics to direct the formation of nervous tissue." Current Opinion in Biomedical Engineering 14 (2020), 59-66. doi:10.1016/j.cobme.2020.05.009.

Key Points: Biomechanics & The Formation Of Nervous Tissue

• Mechanics can be used to guide and accelerate neuronal expansion.

  The central nervous system plays a key role in initiating the autonomic functions and coordinated actions of every being.

  The peripheral nervous system coordinates signal transmission between the central nervous systems and the peripheral organs.

  Neurons have a natural ability to detect mechanical changes in the environment and respond to mechanical loading.

  Axon growth is characterized by navigation of axons through embryonic tissues to form connections at synapses or terminate at end organ receptors and neuromuscular junctions.

  Axons continue to grow as the organism expands in size, by several orders of magnitude.

• It is important that axons develop the ability to adapt to biomechanical forces.

  → An inability to adapt may cause the disconnection of axons from their synaptic targets, considering that tissues expand naturally or change shape during the course of development.

• Mechanics are involved in the growth of the brain.

  → Studies have shown that during gestation, the cortex expands at a rate of 2.5x over 6 weeks.

  → As the brain develops, it places tension on white matter axons thus limiting cortical growth.

• Axon stretch growth and cortical growth have limiting differential rates which may play a role in cortical folding during development.

• Tissue growth can be induced using mechanical stretch.

• Gradual traction on living tissues creates stress that stimulates the regeneration and maintenance of active growth of certain tissues.

• With sufficient blood supply, steady traction of the tissues activates biosynthetic and proliferative functions.1

• Stretching of connective tissues causes nerve epineurium and constriction of the vasculature, with consequential temporary or long-term palsy.

• Stretch-growing of nerves in culture can be achieved by gradual acceleration of the expansion rate, below the rate at which the axon can grow.

• It is possible to avoid neurological complications and pain by gradual application of stretch during limb lengthening (1mm daily).

  Growth cone advancement is driven by mechanotransduction and force generation of cytoskeletal dynamics.

• Lengthening of axons can be induced by the application of force on the distal ends of the axons – a result of the stretch growth technique.

• Axons can withstand a constant application of 25% strain while accommodating normal axon growth.

• Constant application of strains above 25% may result in chromatolysis and disconnection.

• Skin expansion shares similar mechanical parameters and limitations as nerve tissue response to stretch growth. Gradual expansion of tissue expanders increases growth and reduces viscoelastic retraction.3

• There is a correlation between integrin expression within axons and their regenerative capacity.

• Increases in axon tension leads to elongation and growth. Conversely, reduction in tension leads to retraction of the neuronal process.

Clinical Pilates in practice

• Stretching is an important component of neural regeneration and rehabilitation.

• Consider what a constant stretch of 10-20% of range is, and stay within that range to integrate neurodynamics and/or other functional mobility exercises:

  → Drawing the Sword.

  → Footwork sprung below at the Tower.

  → Spine Stretch series.

  → Inversion work.

• Daily traction is required, so encourage low-load stretching (always less than 25%) at regular intervals.

References

1. Hosny GA. Limb lengthening history, evolution, complications and current concepts. J Orthop Traumatol. 2020;21(1):3. Published 2020 Mar 5. doi:10.1186/s10195-019-0541-3

2. Pfister, Bryan J., Jonathan M. Grasman, and Joseph R. Loverde. "Exploiting biomechanics to direct the formation of nervous tissue." Current Opinion in Biomedical Engineering 14 (2020), 59-66. doi:10.1016/j.cobme.2020.05.009.

3. Purnell CA, Gart MS, Buganza-Tepole A, Tomaszewski JP, Topczewska JM, Kuhl E, Gosain AK. Determining the Differential Effects of Stretch and Growth in Tissue-Expanded Skin: Combining Isogeometric Analysis and Continuum Mechanics in a Porcine Model. Dermatol Surg. 2018;44(1):48-52. Epub 2017/07/12. doi: 10.1097/DSS.0000000000001228. PubMed PMID: 28692604; PMCID: PMC6004345.