Extended Abstract
1. Introduction
any researchers believe that loss of postural balance in the face of perturbation is the main reason for the fall in the elderly people [1]. The central nervous system uses two anticipatory and compensatory postural adjustments to maintain, restore, and control postural balance under perturbation. If the anticipatory mechanism be activated in time, earlier or with less delay, the need for more activity of the compensating mechanism will be reduced and, therefore, the displacement of the center of gravity will decrease and the postural balance will be maintained better or restored sooner [2, 3].
Postural control mechanisms in the elderly are impaired [4]. Recently, researchers have proven the possibility of improving the anticipatory mechanism of postural balance control in the elderly with exercises for receiving and throwing the ball [5]. Due to the novelty of these exercises and the lack of a specific training protocol in this area, the aim of this study was to evaluate the effect of an eight-week training protocol focused on the Anticipatory Postural Adjustments (APAs) on the postural control and motor function of the elderly people.
2. Methods & Materials
In this experimental study conducted in 2017, the study population consists of male elderly people in Isfahan, Iran with a history of falls at least once in the last six months. Considering α=0.05, β=0.8 and effect size=0.3 in G*POWER software, 15 samples for each group were calculated, which due to the possibility of sample drop, it was determined 20. After considering the inclusion criteria, 40 eligible individuals were selected and randomly divided into two equal groups. Of them, 18 in the test group (mean age =70.4±3.2, mean height =165.3±6.2 cm, mean weight =65.3±4.2 kg) and 15 in the control group (mean age =69.6±3.1 years, mean height =167±5.5 cm, mean weight =67.3±6.8) completed the evaluations.
The experimental group participated in the exercise program for 8 weeks, 3 sessions per week each for 1 hour. The main movements were a set of throwing and receiving exercises, which included the variables of throwing distance (far or near), throwing direction (high up in the air or down to the ground), throwing type (overhead or lower to chest), weight of the ball (light or heavy), type of the ball (basketball, volleyball, medical), posture (increased or reduced base of support), sitting position on a chair (fixed or adjustable) were manipulated during the program. Footscan 7 (RSscan International, Olen, Belgium) was used to measure postural control of the elderly.
After determining the dominant leg, the subjects were asked to stand on the device with the dominant leg barefoot and with eyes open. The duration of the test was three repetitions of 30 seconds with two minutes of rest between each attempt. The average of these repetitions was recorded as an individual record for further calculations. The Timed Up and Go (TUG) test was used to measure functional mobility of the subjects. It uses the time when the subject rises from a chair with no arms, walks three meters with maximum speed, and then walks back to the chair and sits down. Each subject performed the test twice and the best recorded time was considered as his record. After eight weeks of exercise, the pre-tests were performed again. Repeated-measures ANOVA was used for the analysis of time and group effects at a significance level of 0.05.
3. Results
According to Table 1, the results of within-group and between-group comparisons showed that the eight-week exercise program improved anterior/posterior control, medial/lateral control, overall postural control, and TUG test score (P≤0.05); but in the control group, there were no significant changes (P≥0.05).
4. Conclusion
With the onset of aging, there is a decrease in motor function and balance. One of the reasons for this decrease is the reduced use of APAs in the elderly. Therefore, APAs is significantly delayed in healthy elderly compared to young people, and the muscles with an activity similar to that of primary motor cortex muscles or the moment of impact are used [6]. Delayed muscle activity in the APAs phase in the elderly causes greater displacement of the center of mass after perturbation, indicating greater postural instability [7]. However, clinical practice has not specifically focused on improving the APAs. This may be due to the lack of evidence on the role of exercises focused on APAs in improving postural stability and motor fucntion in the elderly [5].
There, we suggest that APA-based exercises can improve the balance of the elderly and reduce falls in them. In all three postural control indices (anterior/posterior, medial/lateral and overall), a decrease in center of pressure displacement was observed after exercise, indicating an improvement the static balance. Moreover, the functional mobility of the elderly under TUG test decreased by 3.25 seconds, in average, after exercise. The TUG test score is related to Berg Balance Scale score and walking speed; hence, the improvement in the score of TUG test in our study shows that the postural stability of the elderly was improved and they were less likely to be at risk of falling.
It seems that an 8-week training intervention focused on APAs which included throwing and receiving a ball with different weights and sizes and in different directions and positions, can improve postural stability in the elderly. It is possible that a APA-based training program reduces the need to activate the compensatory mechanism by timely activation of the muscles involved in APAs, and reduces the displacement of the center of gravity. These exercises are an effective way to improve the APAs and, thus, postural balance and motor function in the elderly which eventually prevents falling and its irreparable consequences.
Corrective exercise specialists and physiotherapists who work with older adults can use this program along with other training protocols to improve balance and motor function of the older people. The limitations of the present study include: the statistical population limited to one city, short study duration, uncontrolled mental and psychological conditions of the subjects, the use of a convenience sampling technique, and the effect of individual and hereditary differences on test results.
Ethical Considerations
Compliance with ethical guidelines
This study was approved by the Ethics Committee of University of Isfahan (Code: IR.UI.REC1396, 065). All the procedures of the study were explained to participants, and all their questions were answered before they were asked to participate in the study.
Funding
The present paper was extracted from the PhD. thesis of the first author, Department of Corrective Exercises, Faculty of Physical Education, University of Isfahan, Isfahan.
Authors' contributions
All authors equally contributed in preparing this article.
Conflicts of interest
The authors declared no conflict of interest.
Acknowledgements
We wish to express our sincere gratitude to all the elderly, and the University of Isfahan whose cooperation has been a great source of help.
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