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7th EFSMA – European Congress of Sports Medicine, 3rd Central European Congress of Physical Medicine and Rehabilitation, Annual Assembly of the German and the Austrian Society of Physical Medicine and Rehabilitation

Austrian Society of Physical Medicine and Rehabilitation

26.-29.10.2011, Salzburg, Austria

The postural system is affected by static and dynamic muscular fatigue

Meeting Abstract

  • corresponding author presenting/speaker Thomas Bochdansky - Rehaklinik Montafon, Schruns, Austria
  • Dominik Kommenda - SET FH-Technikum Wien, Wien, Austria
  • Clemens Bernreiter - SET FH-Technikum, Wien, Austria
  • Anton Sabo - SET FH-Technikum, Wien, Austria

7th EFSMA – European Congress of Sports Medicine, 3rd Central European Congress of Physical Medicine and Rehabilitation. Salzburg, 26.-29.10.2011. Düsseldorf: German Medical Science GMS Publishing House; 2011. Doc11esm066

DOI: 10.3205/11esm066, URN: urn:nbn:de:0183-11esm0660

Published: October 24, 2011

© 2011 Bochdansky et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en). You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.


Outline

Text

Objective: Human balance is maintained by a complex system of postural control consisting of an efferent information from motoric centers to the muscles and a cluster of afferent information from the periphery towards the central nervous system. The main pathways are the visual, the vestibular and the somatosensory systems. Fatigue is defined by several parameters like metabolic fatigue, structural fatigue, electrophysiological and central fatigue and is related to intrinsic conditions and external loading. This loading can be either static/acyclic or dynamic/cyclic. The aim of our study was to examine, what kind of influence muscular fatigue has on this information system and if there is a difference between static and dynamic fatiguing exercises.

Material/Methods: 23 healthy people (14 female) gave their informed consent to participate in the study. Mean age was 32a (+/-13a). Females had a BMI of 22 (+/-1,8) and males had a BMI of 24 (+/-2,2). Posturography was carried out with a 4-force-plate platform (Tetrax, sunlight) to measure the postural sway during 30 sec. in 8 different positions with eyes open and closed, on hard and soft surface, and with 4 different positions of the cervical spine (standard procedure). Out of this data, general stability index (ST) and a fast-fourier-analysis (FFT) was calculated. FFT allows for differentiation between visual, vestibular and somatosensory part oft he postural system. Muscular fatigue was carried out by a leg-press machine (isoLegpress, BFMC, germany) in sitting position. The test was started with a first posturography. After that a peak force measurement was carried out (3 trials, 5 sec. each) for comparison. A second posturography should demonstrate if there is a short time effect due to this peak force test with maximal voluntary contraction. Subsequently the static (isometric) fatigue test was executed with 5sec. contraction, 1 sec. rest as often until subjects reached 50% of peak force. Immediatly after the last contraction, the 3rd posturography took place, followed by a second peak force measurement. The same protocol was administrated for the dynamic fatigue test with concentric leg extension and eccentric flexion with 1 week in between the 2 tests. The stop criterion was insufficient leg extension.

Results: After static/isometric fatigue test postural sway (ST) increased highly significant between test 1 and 3 and between test 2 and 3. No difference could be found between test 1 and 2. This was true for all 8 positions. FFT Analysis showed to some extend significant changes for the visual system and especially for the somatosensory system and not significant changes in the vestibular system. Peak force did not vary. After dynamic/concentric-eccentric fatigue test ST showed the same effect but FFT gave different results. Only for the frequency band representing the somatosensory system, we found an impact due to fatigue. An impact also could be seen for the first position in other frequencies, but this might represent an effect of increased breathing after exhaustion. To go without saying there was a difference between man and women. Comparing the results of static versus dynamic tests we did not find any substantial differences except minor effects for the somatosensory system during the first minutes after the tests.

Conclusion: Both static and dynamic fatigue has a negative impact on postural stability and might lead to a greater risk of falling. This holds true especially for the somatosensory system. We did not find any difference between static and dynamic disturbance. So we conclude, that the overall perfomance of the muscular system has an influence on the postural System and the risk of fall as could be shown also by Simoneau M. et al. [1] after fatiguing walking. Fatigue increases the postural sway and we assume that this has to be considered in balance training and for strategies to reduce the risk of falls.


References

1.
Simoneau M, Bégin F, Teasdale N. The effect of moderate fatigue on dynamic balance control and attentional demands. J Neuroeng Rehab. 2006;3:22-31.