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Completed

NCT Number: NCT07612358

Comparing Two Training Frequencies of Balance Training for Chronic Ankle Instability

This study compares two progressive hop-to-stabilization balance (PHSB) training schedules with equal total training volume in people with chronic ankle instability (CAI). Current evidence supports the effectiveness of PHSB training for CAI rehabilitation, but no study has directly compared different training frequencies when total training dose is held constant.

Sixty participants with CAI were randomly assigned to three groups: a 4-week group (3 sessions per week, 12 sessions total, n=23), a 6-week group (2 sessions per week, 12 sessions total, n=22), and a waitlist control group (n=12). Each session lasted 20 minutes and followed the standardized PHSB protocol, including single-limb hops to stabilization, hops to stabilization and reach, unanticipated hop to stabilization, and single-limb stance activities with progressive difficulty. The control group received the intervention after study completion.

The primary outcomes are sensory organization measured by the Sensory Organization Test (composite score, six condition equilibrium scores, and four sensory ratios for somatosensory, visual, vestibular, and visual preference) and strategy analysis scores, and regional plantar pressure distribution during walking measured by FreeSTEP (peak force normalized to body weight across the first through fifth metatarsal heads, hallux, medial hindfoot, and lateral hindfoot).

Secondary outcomes include self-reported ankle function (Cumberland Ankle Instability Tool), dynamic balance (Y-Balance Test and side-hop test), static postural stability during single-leg stance measured by FreeSTEP (center of pressure mean velocity, confidence ellipse area, sway length, anteroposterior and mediolateral standard deviation of COP displacement, and Romberg index calculated as eyes-closed to eyes-open ratio of ellipse area), forefoot-rearfoot and medial-lateral plantar load ratios during walking, ankle range of motion measured by goniometer, and ankle muscle strength assessed by manual muscle testing.

This study aims to determine whether different training frequency schedules produce similar or distinct rehabilitation outcomes across sensorimotor, biomechanical, and patient-reported domains, providing evidence for flexible and individualized exercise prescription in CAI management.

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Key information

Conditions

Chronic Ankle Instability, CAI Chronic Ankle Instability

Age range

16 year–49 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Beijing Sport University

Beijing, 100084, China

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • History of at least one lateral ankle sprain with inflammatory signs (swelling, pain) and inability to bear weight on the affected side for at least one day after injury, per International Ankle Consortium criteria.
  • At least two episodes of giving way, recurrent ankle sprains, or perceived ankle instability within 6 months prior to enrollment.
  • Time since first ankle sprain greater than 12 months.
  • Time since most recent ankle sprain greater than 3 months.
  • No history of fracture or surgery in either lower extremity.
  • No other injuries causing inability to bear weight on either lower extremity within the past 3 months.
  • Cumberland Ankle Instability Tool (CAIT) score of 24 or below
  • Physically active: engaging in at least 30 minutes of moderate or higher intensity physical activity on at least 3 days per week.
  • Age 16-49 years.
  • Willing to provide written informed consent -

Exclusion criteria

  • History of lower extremity surgery or lower extremity fracture affecting lower limb function
  • Acute ankle sprain within 6 weeks prior to enrollment
  • Foot or ankle immobilization for more than 48 hours within the past 6 months
  • Neurological, vestibular, or other medical conditions affecting muscle strength or proprioceptive function
  • Currently receiving other rehabilitation treatment for the ankle -

Treatment and study plan

PHSB Training - High Frequency Short Duration

Behavioral

Standardized progressive hop-to-stabilization balance training performed 3 times per week for 4 weeks (12 sessions, 20 minutes per session, 240 minutes total). Training sessions were scheduled with approximately equal inter-session intervals (48-72 hours). The protocol consisted of four components with progressive difficulty levels: (1) single-limb stance activities under eyes-open and eyes-closed conditions on firm and foam surfaces with 7 levels, (2) single-limb hops to stabilization in four directions at three distances (45, 68, 91 cm) with 7 levels, (3) hops to stabilization and reach with 7 levels, and (4) unanticipated hop to stabilization using a numbered 9-grid system with 7 levels. Progression occurred when participants completed a level without errors. n=23.

PHSB Training - Low Frequency Long Duration

Behavioral

Identical progressive hop-to-stabilization balance training protocol as Intervention 1, performed 2 times per week for 6 weeks (12 sessions, 20 minutes per session, 240 minutes total). Training sessions were scheduled with approximately equal inter-session intervals (72-96 hours). Training content, progression criteria, difficulty levels, and exercise components were the same as the 4-week protocol. The only difference was the distribution of training sessions across a longer period at a lower weekly frequency. n=22.

Primary outcomes

  1. Cumberland Ankle Instability Tool (CAIT)

    Time frame: Baseline (within 1 week before intervention) and post-intervention (within 1 week after completion of the training program)

    Self-reported ankle function questionnaire assessing perceived ankle instability during daily and sporting activities. Total score ranges 0-30, with higher scores indicating better ankle stability. A score below 24 indicates chronic ankle instability per International Ankle Consortium criteria. The minimal clinically important difference is 3 points. The Chinese version has demonstrated high internal consistency (Cronbach alpha 0.815) and test-retest reliability (ICC 0.99).

  2. Y-Balance Test (YBT)

    Time frame: Baseline (within 1 week before intervention) and post-intervention (within 1 week after completion of the training program)

    Dynamic balance assessment measuring maximum reach distance in three directions (anterior, posteromedial, posterolateral) during single-leg stance on the affected limb. Reach distances were normalized to limb length and expressed as percentage. Three trials per direction with the best value selected, and the average of three directions used as the final score. Higher scores indicate better dynamic balance.

Secondary outcomes

  1. SOT Sensory Ratios

    Time frame: Baseline and post-intervention (within 1 week after completion of the training program)

    Four sensory ratios derived from the Sensory Organization Test: somatosensory ratio (Condition 2 / Condition 1), visual ratio (Condition 4 / Condition 1), vestibular ratio (Condition 5 / Condition 1), and visual preference ratio ((Condition 3 + Condition 6) / (Condition 2 + Condition 5)). Higher scores indicate better utilization of the corresponding sensory system for postural control. These ratios assess changes in sensory reweighting strategies following intervention.

  2. SOT Balance Performance

    Time frame: Baseline and post-intervention (within 1 week after completion of the training program)

    Composite equilibrium score (overall balance, range 0-100), individual equilibrium scores for each of the six Sensory Organization Test conditions (Condition 1 through Condition 6, each range 0-100), and strategy analysis scores indicating the relative use of ankle-dominant versus hip-dominant postural control strategies. Higher equilibrium and strategy scores indicate better balance performance. Assessed using a virtual dynamic balance testing system.

  3. Regional Plantar Pressure Distribution During Walking

    Time frame: Baseline and post-intervention (within 1 week after completion of the training program)

    Peak force normalized to body weight (PF/W, N/kg) at eight anatomical foot regions during level walking, measured by FreeSTEP system at 200 Hz sampling frequency: first through fifth metatarsal heads (M1-M5), hallux (T1), medial hindfoot (HM), and lateral hindfoot (HL). Data collected over 30 seconds of steady-state walking and averaged across 9 representative gait cycles. Changes in regional pressure distribution reflect altered foot loading patterns and ankle inversion tendency.

  4. Static Postural Stability Parameters During Single-Leg Stance

    Time frame: Baseline and post-intervention (within 1 week after completion of the training program)

    Center of pressure parameters during 10-second single-leg stance on the affected limb, measured by FreeSTEP system under both eyes-open and eyes-closed conditions: COP mean velocity (mm/s), confidence ellipse area (mm2), sway length (mm), and standard deviation of COP displacement in anteroposterior (SD-Y) and mediolateral (SD-X) directions. Three trials per condition with 60-second rest intervals, averaged for analysis. Lower values indicate better postural stability.

  5. Romberg Index

    Time frame: Baseline and post-intervention (within 1 week after completion of the training program)

    Ratio of eyes-closed to eyes-open postural stability parameters calculated from FreeSTEP single-leg stance data, including confidence ellipse area ratio, sway length ratio, and COP velocity ratio. Higher values indicate greater reliance on visual input for postural control. A decrease following intervention suggests reduced visual dependence and improved proprioceptive and vestibular contributions to balance.

  6. Plantar Load Distribution Ratios During Walking

    Time frame: Baseline and post-intervention (within 1 week after completion of the training program)

    Forefoot-to-rearfoot and medial-to-lateral plantar load distribution ratios (%) during walking, measured by FreeSTEP dynamic analysis. Changes in these ratios reflect shifts in overall foot loading strategy related to ankle inversion tendency in individuals with chronic ankle instability.

  7. Side-Hop Test

    Time frame: Baseline and post-intervention (within 1 week after completion of the training program)

    Timed functional performance test measuring the time required to complete 10 lateral hops over two lines spaced 30 cm apart on the affected limb, performed barefoot. Three trials with the best time recorded. Shorter completion time indicates better dynamic ankle function and neuromuscular control.

  8. Ankle Range of Motion

    Time frame: Baseline and post-intervention (within 1 week after completion of the training program)

    Active ankle joint range of motion measured by goniometer, including dorsiflexion, plantarflexion, inversion, and eversion of the affected ankle, recorded in degrees. Three trials per direction will be performed, and the maximum value will be used for analysis. This measure provides information on peripheral musculoskeletal adaptations following training.

  9. Ankle Muscle Strength

    Time frame: Baseline and post-intervention (within 1 week after completion of the training program)

    Isometric ankle muscle strength of dorsiflexors, plantarflexors, invertors, and evertors assessed using a hand-held dynamometer and recorded in Newtons. Three trials per direction will be performed, and the maximum value will be used for analysis. This measure provides information on peripheral musculoskeletal adaptations following training.

Sponsors and collaborators

Lead sponsor

University of Utah

Other

Collaborators

  • Beijing Sport University

Registry information

Official study title

Comparing Two Training Frequencies of Dose-equivalent Hop-to-stabilization Balance Training on Sensorimotor Function and Plantar Biomechanics in Chronic Ankle Instability: a Randomized Controlled Trial

Important dates

Study start
2023
Primary completion
2025
Study completion
2025
First posted
May 28, 2026
Registry last updated
May 28, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

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This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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