The Effects of Bicycle Simulator Training on Anticipatory and Compensatory Postural Control in Older Adults: Study Protocol for a Single-Blind Randomized Controlled Trial

Abstract

Background: Falls are the leading cause of fatal and non-fatal injuries among older adults. Perturbation-Based-Balance Training (PBBT) is a promising approach to reduce fall rates by improving reactive balance responses. PBBT programs are designed for older adults who are able to stand and walk on a motorized treadmill independently. However, frail older adults, whose fall rates are higher, may not have this ability and they cannot participate. Thus, there is a critical need for innovative perturbation exercise programs to improve reactive balance and reduce the fall risks among older adults in a wider range of functioning. Trunk and arms are highly involved in reactive balance reactions. We aim to investigate whether an alternative PBBT program that provides perturbations during hands-free bicycling in a sitting position, geared to improve trunk and arm reactive responses, can be transferred to reduce fall risks and improve balance function among pre-frail older adults. Methods: In a single-blinded randomized-controlled trial, 68 community-dwelling pre-frail older adults are randomly allocated into two intervention groups. The experimental group receives 24-PBBT sessions over 12-weeks that include self-induced internal and machine-induced external unannounced perturbations of balance during hands-free pedaling on a bicycle-simulator system, in combination with cognitive dual-tasks. The control group receives 24 pedaling sessions over 12-weeks by the same bicycle-simulator system under the same cognitive dual-tasks, but without balance perturbations. Participants' reactive and proactive balance functions and gait function are assessed before and after the 12-week intervention period (e.g., balance reactive responses and strategies, voluntary step execution test, postural stability in upright standing, Berg Balance Test, Six-meter walk test, as well as late life function and fear of falling questionnaires). Discussion: This research addresses two key issues in relation to balance re-training: (1) generalization of balance skills acquired through exposure to postural perturbations in a sitting position investigating the ability of pre-frail older adults to improve reactive and proactive balance responses in standing and walking, and (2) the individualization of perturbation training to older adults' neuromotor capacities in order to optimize training responses and their applicability to real-life challenges. Clinical Trial Registration: www.clinicaltrials.gov, NCT03636672 / BARZI0104; Registered: July 22, 2018; Enrolment of the first participant March: 1, 2019. See Supplementary File.

Keywords: aging; balance control ability; balance reactive response; balance training intervention; falls.

Conflict of interest statement

SB and IM own a patent on some of the technology (PerStBiRo system) used in the perturbation system. We submitted a technical article describing the PerStBiRo system to BMC Geriatrics (no. BGTC-D-20-00476). The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Copyright © 2021 Batcir, Lubovsky, Bachner and Melzer.

Figures

Figure 1

Photos of the PerStBiRo system. The system provides Medio-Lateral tilting perturbations in two ways: self-induced internal (A) and external machine-induced (B) perturbations. (A) Represent a self-induced 'internal' balance perturbation, while the trainee keeps balance when the motor is released, and the moving platform is “floating” during pedaling. (B) Represent an external machine-induced programmed balance perturbation during bicycling. The PerStBiRo system is composed of a stationary training bicycle mounted on a moving platform, servo-motor, motor's motion control system, gear mechanism, motion capture system (Microsoft KinectKM system), safety harness, TV screen and a trainer station with the host PC. The host PC consists the main computer program and serves as a user interface for creating training programs, running them, monitoring upper body movements in real time and analyzing the post-session balance responses.

Figure 2

Training session templates for PerTSBR and TSBR groups. Resistance= stationary bicycle resistance while pedaling, DT=dual tasks, Inter/Exter= internal/external, “floating” = a PerStBiRo–system's mode in which the moving platform and the stationary bicycle are unfixed and unstable; thus, it is subjected to tilting by the forces acting on it. Fixed mode is when the PerStBiRo is locked vertically, and it is used as a regular stationary bicycle. Motion capture mode refers to whether the motion capture system i.e., Microsoft KinectKM system works and monitors the trainee's movements, providing them with real-time external cues of their balance reactions. Levels refer to the level of the training program (details in Table 1).

Figure 3

Medio-lateral perturbation system to evoke reactive trunk and upper body balance reactions.

Figure 4

(A) sample of upper body movements (horizontal colored lines) and the PerStBiRo system's stationary bicycle (horizontal black lines) by time during the calibration phase (left of the dotted line in B,C) and during balance perturbation exercise phase, focusing on the upper body reactive balance response of an 82-year-old trainee following a programmed 20° right tilting perturbation (A and gray timelines in B,C). Shoulder line angle—the angle of the participant's shoulder line and the ground (B, horizontal purple line); Head–Neck angle—the angle of the participant's head-to-neck line and the vertical line to the ground (B, horizontal green line). Points 1 + 2 indicate external perturbations that lead to sharp and large upper body balance reactions. The time range 1–2 indicates internal perturbations, the upper body oscillations when riding on an unstable surface—as seen the horizontal black lines, that represent the stationary bicycle angles, are not exactly on the vertical 0° position.

Figure 5

An example of the ability of the 86-years old trainee to reactively respond to unannounced perturbations during hands-free pedaling along the training sessions. (A) Low-magnitude perturbations in block right-left training of 2.5° tilt (i.e., the black arrows). A sample of 26 s that represents the participant's ability to consistently react to perturbations [shoulder line angles (purple line) reacts in the opposite direction and related to the black line perturbations]. (B) An example of effective trainee's reactive balance responses during random unexpected moderate-magnitude (6°-10° tilt) perturbation training. A sample of 30 s that represents generally organized and controlled shoulders/trunk movements [shoulder line angles (purple line] during hands-free pedaling, and particularly organized and effective upper-body balance responses (shoulders' response, represented by purple line rises in a manner adapted to the perturbations). (C) A sample of 60 s during the fourteenth session that represents the participant's ability to respond reactively to high-magnitude (8°-12° tilt) random unannounced external perturbations (spikes in the black line that represent the stationary bicycle training angles, black arrows) and respond proactively to self-induced perturbations during the “floating” mode of the moving platform (gentle long humps in stationary-bicycle-training black line, red arrows). Generally, the shoulders' balance responses show an organized response appropriate to the challenge of balance, i.e., the shoulders' purple line move in the opposite direction when the self-induced perturbations occurred and usually also in the case of unannounced external perturbations.