Optimal Intensity of Reactive Balance Training Post-stroke

Optimal Intensity of Reactive Balance Training Post-stroke: a Randomized Controlled Trial

Falls in daily life are a serious risk for people with stroke. A new type of balance training, called reactive balance training (RBT). may help to reduce this risk of falling. In some previous studies participants improved their balance reactions a lot after RBT, whereas others did not improve at all. These studies used different types and amounts of training. Differences in training program features might explain differences in the study results.

Training intensity is the difficulty or challenge of the training program. For other types of exercise (like 'cardio' or strength training) if the intensity of exercise is increased, someone can get the same benefits in less time than with lower intensity exercise. Physiotherapists report that they have limited time in rehabilitation to do everything they need to do with their stroke patients, so it would be valuable to know if high-intensity RBT improves balance reactions quickly. The goal of this study is to see if more intense RBT improves balance reactions faster than less intense RBT.

People with chronic stroke will be randomly placed in one of three groups: high-intensity RBT, moderate-intensity RBT, or a walking control group. The investigators will find the fastest moving platform speed that participants can respond to with single step (multi-step threshold). There will then be 4 1-hour long training sessions in one week. Participants in the high-intensity group will experience platform movements that are 50% faster than the multi-step threshold. Participants in the moderate-intensity group will experience platform movements at the multi-step threshold. Participants in both RBT groups will experience 36 multi-directional platform movements in each training session, causing them to start to fall forwards, to the left, or to the right. Participants in the walking group will walk on the platform 36 times without any platform movements. The investigators will measure how quickly people improve their balance reactions over the training program.

Study Overview

• Status: Recruiting
• Conditions: Stroke; Accidental Fall
• Intervention / Treatment: Behavioral: Reactive balance training; Behavioral: Walking

Detailed Description

Remaining active after stroke is essential to recovery, maintaining quality of life, and reducing secondary stroke risk. However, impaired balance control post-stroke increases fall risk, contributes to fear of falling, and reduces overall mobility, activity, and community integration. Therefore, effective interventions to improve balance control and reduce fall risk are essential to ongoing recovery and quality of life post-stroke. However, while there is unequivocal evidence that exercise, specifically balance training, is the most effective intervention for preventing falls in older adults without stroke, it is unclear if exercise prevents falls after stroke. Effective balance reactions (e.g., reactive stepping) are essential to avoid falling following a loss of balance, or balance perturbation. Reactive balance training (RBT), where clients experience repeated balance perturbations, is a novel type of exercise that aims to improve control of balance reactions. The investigators found that RBT improves reactive stepping ability in people with stroke. The investigators' recent meta-analysis found that RBT reduces rate of falls in daily life by ~40% among older adults and people with neurologic conditions, including stroke.

Clinicians are unsure how to optimally prescribe RBT. Exercise is often prescribed considering frequency, intensity, time, and type; these parameters are interdependent. For example, as intensity increases, frequency or time can decrease to achieve similar benefits. Clinicians report that limited time in rehabilitation services and competing rehabilitation goals and priorities mean that there is little time available to include RBT in a client's treatment plan. Therefore, it would be valuable to know if a short duration of high-intensity RBT can improve reactive balance control post-stroke. However, it is possible that people with stroke would not tolerate high intensity perturbations and, therefore, require lower-intensity but long-duration RBT. No study has directly compared different RBT training intensities among people with stroke.

The purpose of this study is to determine the optimal intensity of RBT post-stroke. The 'optimal' intensity is the intensity that improves reactive balance control in fewer sessions, without any apparent negative consequences (i.e., no increase in adverse outcomes). Responses to backward-fall perturbations will be assessed at the end of each session, and at the one-week retention time-point. An untrained perturbation (i.e., backward-fall perturbation) will be used to test transfer of learning to a novel context. Participants will experience 3 forward-directed platform translations, evoking a backward loss of balance, at the multi-step threshold. Because backward falls are more challenging than forward or lateral falls, a backward-fall perturbation at the forward-fall multi-step threshold should evoke a multi-step reaction, at least prior to training. Testing at each participant's multi-step threshold ensures that participants will initially experience challenges responding to the perturbation and there is room for improvement with training. The primary outcome will be number of steps taken to recover balance.

The investigators will calculate the learning rate for each participant by fitting an exponential function, a+b(e^(- t/x) ), to their data (average number of steps taken at each assessment time point), where a and b are constants, t is the assessment time point, and x is the learning rate.

The investigators expect that high-intensity training (50% above the multi-step threshold) will improve reactive stepping ability faster than moderate-intensity training (at the multi-step threshold). If the first reactive step is not effective in avoiding a fall after a loss of balance, additional steps must be taken; therefore, the number of steps needed to recover from a loss of balance is a global indicator of the effectiveness of balance reactions. The investigators will assess reactions to novel, untrained, balance perturbations throughout training, and calculate the rate of decline in average number of steps taken to recover balance (i.e., learning rate). Retention of learning will be assessed one week post-training. The investigators' primary hypotheses are:

1. Adaptation rate will be faster for high-intensity RBT than moderate-intensity RBT;
2. Adaptation rate will be faster for both RBT groups than a walking control group; and
3. Both RBT groups will have better retention of learning than the walking control group; i.e., the RBT groups will take fewer steps to respond to the novel perturbation than the walking control group one week post-training.

Secondary objectives are to compare the rate of adverse outcomes between groups, and to determine the effect of different intensities of RBT on the mechanisms underlying improved reactive stepping ability, functional balance, falls efficacy, and participation in daily activities.

• Study Type: Interventional
• Enrollment (Estimated): 63
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Avril Mansfield, PhD; Phone Number: 7831 416-597-3422; Email: avril.mansfield@uhn.ca
• Study Contact Backup: Name: Nigel Majoni; Email: nigel.majoni@mail.utoronto.ca

Study Locations

• Canada
  • Ontario
    • Toronto, Ontario, Canada, M5G 2A2
      • Recruiting
      • Toronto Rehabilitation Institute
      • Contact: Avril Mansfield, PhD; Phone Number: 7831 416-597-3422; Email: avril.mansfield@uhn.ca

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Chronic stroke (>6 months post-stroke)

Exclusion Criteria:

• Are unable to stand independently without upper-limb support for >30 seconds and/or walk independently (without a gait aid) for ≥10 metres;
• Have another neurological condition that could affect balance control (e.g., Parkinson's disease);
• Have cognitive impairment (Montreal Cognitive Assessment8 score <26), or severe language or communication difficulties affecting understanding instructions;
• Have contraindications to RBT (has described by Mansfield et al., 2021), such as osteoporosis, activity restrictions due to cardiac event/surgery, or severe spasticity in the lower extremity; and/or
• Are currently attending in- or out-patient physiotherapy or supervised exercise.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: High intensity reactive balance training; Training sessions will be overseen by a physiotherapist and will last for 1 hour over 4 consecutive days.Participants assigned to the RBT groups will experience 36 multi-directional (left-, right-, and forward-fall) perturbations in each training session, presented in an unpredictable sequence. Balance perturbations will be provided using a custom moving platform. Participants assigned to high-intensity RBT will experience perturbations at 150% of the multi-step threshold; for example, for a multi-step threshold of 2 m/s^2 the high intensity will be 3 m/s^2.	Behavioral: Reactive balance training; Reactive balance training involves clients experiencing repeated balance perturbations so that they can practice and improve control of reactions to avoid falling after a loss of balance.
Active Comparator: Moderate intensity reactive balance training; Training sessions will be overseen by a physiotherapist and will last for 1 hour over 4 consecutive days.Participants assigned to the RBT groups will experience 36 multi-directional (left-, right-, and forward-fall) perturbations in each training session, presented in an unpredictable sequence. Balance perturbations will be provided using a custom moving platform. Participants assigned to the moderate-intensity RBT group will experience perturbations at the multi-step threshold.	Behavioral: Reactive balance training; Reactive balance training involves clients experiencing repeated balance perturbations so that they can practice and improve control of reactions to avoid falling after a loss of balance.
Sham Comparator: Walking control group; Training sessions will be overseen by a physiotherapist and will last for 1 hour over 4 consecutive days. Participants in the walking control group will complete 36 unperturbed walking trials on the moving platform in each training session.	Behavioral: Walking; Overground walking.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of steps	Learning rate for number of steps to recover from 'backward fall' balance perturbations	One week

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Step initiation time	Time from perturbation onset time to foot off time	One week post-training
Step execution time	Time from foot off to foot contact of the first step	One week post-training
Step length	Difference in foot position from foot off to foot contact	One week post-training
Braking impulse	Antero-posterior shear force generated over time on step contact	One week post-training
Mechanical margin of stability	Distance between the extrapolated centre of mass (incorporating centre of mass position and velocity) and the edge of the base of support	One week post-training
mini-Balance Evaluation Systems test	Scale range: 0-28; higher values indicate better outcome	One week post-training
Falls Efficacy Scale International	Scale range: 10-100; higher values indicate worse outcome	One week and 12 months post-training
Adverse outcomes		Two weeks

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Fall incidence	Falls in daily life	12 months post-training
Injurious fall incidence		12 months post-training
5-level EuroQoL health status measure (EQ-5D-5L)	Scale range for descriptive component: 5-25, higher values indicate worse outcome; Scale range for visual analogue scale: 0-100, higher values indicate better outcome	One week and 12-months post-training
Number of participants with fear of falling		One week and 12-months post-training
Number of participants with activity curtailment due to fear of falling		One week and 12-months post-training

Collaborators and Investigators

• Sponsor: Toronto Rehabilitation Institute
• Collaborators: Heart and Stroke Foundation of Canada
• Investigators: Principal Investigator: Avril Mansfield, PhD, University Health Network, Toronto

Study record dates

Study Major Dates

• Study Start (Actual): November 11, 2024
• Primary Completion (Estimated): June 1, 2026
• Study Completion (Estimated): June 1, 2027

Study Registration Dates

• First Submitted: August 6, 2024
• First Submitted That Met QC Criteria: August 12, 2024
• First Posted (Actual): August 15, 2024

Study Record Updates

• Last Update Posted (Actual): March 25, 2025
• Last Update Submitted That Met QC Criteria: January 22, 2025
• Last Verified: August 1, 2024

More Information

Terms related to this study

• Keywords: Rehabilitation; Exercise; Postural balance
• Additional Relevant MeSH Terms: Cerebrovascular Disorders; Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Vascular Diseases; Cardiovascular Diseases; Stroke
• Other Study ID Numbers: 24-5322

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No