Does Tai Chi improve plantar sensory ability? A pilot study

BACKGROUND

Aging adversely affects balance and increases the propensity to slip and fall. Loss of plantar sensation due to diabetic peripheral neuropathy and other diseases has been shown to further increase this propensity to fall. The ancient Chinese art of Tai Chi has been previously shown as a method to improve balance in healthy elderly adults.

METHODS

The aim of this study was to determine if Tai Chi intervention improved both balance and plantar sensory perception in healthy elderly adults and elderly adults with diabetes and plantar sensory loss. Elderly subjects (mean +/- SD age = 73.1 +/- 5.9 years, n = 18) were tested for plantar sensory ability and several balance metrics before Tai Chi training and again after 6 months of weekly sessions. Participants were grouped by initial sensory perception scores (as measured by a vibrometer) in order to make inferences on the effects of Tai Chi on sensory perception.

RESULTS

Plantar sensation results show all participants showed significant improvement in sensory ability with the 6 months of Tai Chi training. All groups also had a general improvement in all balance measures, with the greatest improvement seen in those subjects with large sensory losses. Hemoglobin A1C measurements also decreased as a result of the intervention.

CONCLUSION

This study demonstrates the effectiveness of Tai Chi training as a method of improving plantar sensation and balance in elderly adults and elderly adults with diabetes with a large plantar sensation loss.

Classification of the extracellular fields produced by activated neural structures

BACKGROUND

Classifying the types of extracellular potentials recorded when neural structures are activated is an important component in understanding nerve pathophysiology. Varying definitions and approaches to understanding the factors that influence the potentials recorded during neural activity have made this issue complex.

METHODS

In this article, many of the factors which influence the distribution of electric potential produced by a traveling action potential are discussed from a theoretical standpoint with illustrative simulations.

RESULTS

For an axon of arbitrary shape, it is shown that a quadrupolar potential is generated by action potentials traveling along a straight axon. However, a dipole moment is generated at any point where an axon bends or its diameter changes. Next, it is shown how asymmetric disturbances in the conductivity of the medium surrounding an axon produce dipolar potentials, even during propagation along a straight axon. Next, by studying the electric fields generated by a dipole source in an insulating cylinder, it is shown that in finite volume conductors, the extracellular potentials can be very different from those in infinite volume conductors. Finally, the effects of impulses propagating along axons with inhomogeneous cable properties are analyzed.

CONCLUSION

Because of the well-defined factors affecting extracellular potentials, the vague terms far-field and near-field potentials should be abandoned in favor of more accurate descriptions of the potentials.