A study design based on a randomized controlled trial – parallel group design was used. The manuscript conforms to CONSORT guidelines.
Participants were recruited through advertisements in local newspapers and on the Internet, and covered the metropolitan region of Poznań, Poland. Eligibility criteria were community-dwelling women aged 65 and over. The candidates had no contraindications to participating in physical activity and gave their informed consent to participate in the experiment. Participants scored at least 8 on the Abbreviated Mental Ability Test29. Subjects taking medications likely to interfere with the natural control of postural stability, users of orthopedic equipment, patients with a neurological disease (Parkinson’s or Alzheimer’s disease), with a significant alteration in perception visual and/or auditory, and subjects who undertake or have undertaken regular physical activity in the past 3 years were not eligible for the program.
Following randomization using the computer program Statistica 13.4 (TIBCO Software Inc., Palo Alto, CA), participants were divided into two groups: the intervention group (IG) and the control group (CG). .
The postural stability of the participants was studied by determining their ability to control the displacement of the center of pressure of the body (COP). For this purpose, the Balance Platform AccuSway Plus model was used, as well as the Balance Trainer software. The system recorded changes in COP position in the anteroposterior (AP) and mediolateral (ML) directions. The sampling rate was set at 100 Hz. The COP is a reliable parameter to assess postural stability and vertical balance control30. The results of the four COP parameters described in Table 1 were analyzed statistically.
Two measurement sessions took place: the first (baseline) took place during the week before the start of the exercise program and the second (12-week follow-up) just after its end (March and June 2016 respectively). The women in IG participated in the exercise program, while the women in CG were instructed to make no changes to their current lifestyles, and in particular not to undertake any new structured physical activity. The participants, the JDE specialist as well as those who carried out the measurements were unaware of the purpose of this study and the fact of belonging to a group.
The research project as well as all experiments were positively evaluated and approved by the Bioethics Committee of Poznan University of Medical Sciences (resolution 1046/15).
The trial was registered on 08/20/2021 on ClinicalTrials.gov (ID: NCT05015777).
Workouts took place twice a week for 45 min each over a 12 week period and took place in the university gymnasium. Each training included rhythmic exercises using the Jaques – Dalcroze Eurhythmics method with piano accompaniment and music played electronically. The training sessions were led by a JDE specialist.
Each class consisted of three parts: warm-up (~10 min), main part (~30 min) and cool-down (~5 min). Exercises with the use of the JDE method consist mainly in the repetition of predefined musical sequences using body movements. In addition to the physical layer, the cognitive layer was equally important: when performing a given movement exercise, participants had to concentrate in order to respond appropriately to additional tasks, such as changes in pitch of the piece (for example, when the pitch was high, they had to tiptoe, when low – in a half-squat) as well as dynamic, agogic and articulatory sequence changes in the music . The exercises included movements based on rhythmic themes where the participants had to adjust the speed of their movement to the tempo of the music, the rhythmic transformation of themes and polyrhythms (the arms move at a different rhythm than the legs). There were also inhibition-incitement exercises (inhibition and stimulation of movement, i.e. stopping movement when the music stops and resuming movement when the accompaniment resumes), improvisations of movements and exercises developing the control of the balance of the body, the independence of the movements and their coordination.25.
Balance Platform Test
Participants had to perform a movement task while standing on a posturographic platform. A feedback balance analysis protocol was used – subjects saw a dot on the screen that reflected their COP. By tilting their bodies in different directions, they were able to observe changes in the position of their COP in real time. The task for the participants was to do this in such a way as to aim their COP at the appropriate targets marked on the screen, in the correct order (Fig. 1).
Given the natural heterogeneity of the group in terms of physical fitness due to the age of the subjects, the distances of the extreme zones from the central zone, and therefore the range of deviation, were decided to be determined for each participant individually. . For this purpose, the maximum deviations of each subject in the AP and ML directions were first determined, then the software automatically determined the centers of the targets at a distance of 75% of the maximum deviation in a given direction. This ensured that each subject leaned their torso relatively within the same range and that the task was within their ability. The results of the maximum torso inclination ranges were also statistically analyzed.
The test consisted of two main components: (1) the moving COP point phase and (2) the COP point holding phase. The task was to move the COP point into individual targets (in a pre-determined order), each time the COP point had to be held inside each target’s zone for at least one second, after which the target became inactive (darker), which was a signal of its correct passage. At the same time, the next (active) target would light up, indicating that the COP point should be moved into that target, where it should again be held for at least one second, and so on. Each time the extreme target was exceeded, it was necessary to return to the central target. A similar trial measuring changes in postural stability in a biofeedback model under the influence of training has already been used in other experiments.31.32.
The posturographic platform was fixed on a flat surface, in front of the subject at a distance of 1.5 m at eye level was placed a 27-inch monitor. The room was soundproofed to ensure peace and quiet. On the platform were lines specifying the appropriate distances and angles of foot placement to ensure that the subject stood in the same place on each subsequent trial. The feet on the platform were placed naturally next to each other at hip width, with the toes pointing gently outward.
Each participant received verbal instructions on how to perform the test, with particular emphasis that the test should be performed as quickly and accurately as possible, moving the COP point by the shortest possible path to the target, and once reached, trying to keep the COP point as still as possible in the center of the target until it becomes inactive (goes dark). The person performing the test then performed a demonstration of the entire test. The final step was for the subjects to complete two pre-test trials, followed by a third trial, the results of which were analyzed statistically.
The results of the descriptive statistics were presented as means with standard deviation (mean ± SD). Postural stability test results were presented as means and 95% confidence intervals. A two-way analysis of variance (ANOVA) was performed. Eta-square analysis was used to determine the effect size. Tukey’s post-hoc test was performed if there were significant main or interaction effects. Differences between groups in the single study session area and between study sessions in the group area were determined using the Mann-Whitney method. you test with continuity correction. The statistical significance level was set at 5%. All calculations were performed using Statistica 13.4 (TIBCO Software Inc., Palo Alto, CA)25.
All procedures performed in studies involving human participants complied with institutional and/or national research committee ethical standards and the 1964 Declaration of Helsinki and subsequent amendments or comparable ethical standards.
Informed consent was obtained from all subjects involved in the study.