Water-Inertia-Based Dynamic Stability Training for Balance and Postural Control in Healthy Young Women

NCT07812103 | Completed

• 2 other identifiers: 2024-0666-001P01-202407-01-004
• Study Type: interventional
• Target: 30
• Locations: 1 country
• Sites: 1

Brief Summary

This randomized controlled study evaluated the effects of a 10-week dynamic stability training program using a mobile water load compared with a mass-matched stable load in healthy young women. Thirty participants were randomly assigned to either water-inertia-based unstable-load training or stable-load training. Both groups completed the same supervised exercises three times per week, using vests with the same total external mass; the main difference between groups was whether the load inside the vest was mobile or stable. Outcomes were assessed before training, after 5 weeks, and after 10 weeks. The study evaluated dynamic balance, postural sway during single-leg stance, and other physical-performance outcomes to determine whether mobile water loading produced different training adaptations from stable loading.

Conditions

Postural Control; Dynamic Stability

Keywords

water-inertia loading; unstable-load training; healthy young women; dynamic stability training; dynamic balance; postural control; Y-Balance Test; center of pressure; single-leg stance

Outcome Measures

Primary Outcomes (16)

• Normalized Anterior Reach Distance on the Y-Balance Test

  Dynamic postural control was assessed using the lower-quarter Y-Balance Test. Participants performed three valid anterior reach trials while maintaining single-leg stance. The maximum reach distance was retained and normalized to the corresponding limb length: normalized reach distance (%) = maximum reach distance / limb length × 100. Higher values indicate greater normalized reach performance.

  Baseline, Week 5, and Week 10

• Normalized Posteromedial Reach Distance on the Y-Balance Test

  Participants performed three valid posteromedial reach trials during the lower-quarter Y-Balance Test. The maximum reach distance was retained and normalized to the corresponding limb length: normalized reach distance (%) = maximum reach distance / limb length × 100. Higher values indicate greater normalized reach performance.

  Baseline, Week 5, and Week 10

• Normalized Posterolateral Reach Distance on the Y-Balance Test

  Participants performed three valid posterolateral reach trials during the lower-quarter Y-Balance Test. The maximum reach distance was retained and normalized to the corresponding limb length: normalized reach distance (%) = maximum reach distance / limb length × 100. Higher values indicate greater normalized reach performance.

  Baseline, Week 5, and Week 10

• Y-Balance Test Composite Score

  The composite score was calculated from the maximum valid anterior, posteromedial, and posterolateral reach distances normalized to limb length: composite score (%) = (maximum anterior + maximum posteromedial + maximum posterolateral reach distance) / (3 × limb length) × 100. Higher values indicate greater overall Y-Balance Test performance.

  Baseline, Week 5, and Week 10

• Center-of-Pressure Total Distance During Eyes-Open Single-Leg Stance

  Postural sway was assessed using a force platform during 30-second eyes-open single-leg stance. Total CoP distance (cm) represented the cumulative path length of the center-of-pressure trajectory during each valid trial. Three trial-specific values were averaged for analysis. Lower values represent a shorter CoP trajectory during the test condition.

  Baseline, Week 5, and Week 10

• Anteroposterior CoP RMS During Eyes-Open Single-Leg Stance

  Anteroposterior root-mean-square (AP RMS) displacement of the center of pressure was calculated during 30-second eyes-open single-leg stance and expressed in centimeters. AP RMS represents the dispersion of CoP displacement about its mean position in the anteroposterior direction. Three trial-specific values were averaged for analysis.

  Baseline, Week 5, and Week 10

• Mediolateral CoP RMS During Eyes-Open Single-Leg Stance

  Mediolateral root-mean-square (ML RMS) displacement of the center of pressure was calculated during 30-second eyes-open single-leg stance and expressed in centimeters. ML RMS represents the dispersion of CoP displacement about its mean position in the mediolateral direction. Three trial-specific values were averaged for analysis.

  Baseline, Week 5, and Week 10

• Center-of-Pressure Total Distance During Eyes-Closed Single-Leg Stance

  Postural sway was assessed using a force platform during 20-second eyes-closed single-leg stance. Total CoP distance (cm) represented the cumulative path length of the center-of-pressure trajectory during each valid trial. Three trial-specific values were averaged for analysis. Lower values represent a shorter CoP trajectory during the test condition.

  Baseline, Week 5, and Week 10

• Anteroposterior CoP RMS During Eyes-Closed Single-Leg Stance

  Anteroposterior root-mean-square (AP RMS) displacement of the center of pressure was calculated during 20-second eyes-closed single-leg stance and expressed in centimeters. AP RMS represents the dispersion of CoP displacement about its mean position in the anteroposterior direction. Three trial-specific values were averaged for analysis.

  Baseline, Week 5, and Week 10

• Mediolateral CoP RMS During Eyes-Closed Single-Leg Stance

  Mediolateral root-mean-square (ML RMS) displacement of the center of pressure was calculated during 20-second eyes-closed single-leg stance and expressed in centimeters. ML RMS represents the dispersion of CoP displacement about its mean position in the mediolateral direction. Three trial-specific values were averaged for analysis.

  Baseline, Week 5, and Week 10

• Knee Extension Peak Torque Relative to Body Weight at 60°/s

  Concentric knee extension strength was assessed using an isokinetic dynamometer at an angular velocity of 60°/s. Peak torque was normalized to body weight and expressed as a percentage of body weight (PT/BW, %). Higher values indicate greater knee extensor torque relative to body weight.

  Baseline, Week 5, and Week 10

• Knee Flexion Peak Torque Relative to Body Weight at 60°/s

  Concentric knee flexion strength was assessed using an isokinetic dynamometer at an angular velocity of 60°/s. Peak torque was normalized to body weight and expressed as a percentage of body weight (PT/BW, %). Higher values indicate greater knee flexor torque relative to body weight.

  Baseline, Week 5, and Week 10

• Ankle Inversion Peak Torque Relative to Body Weight at 60°/s

  Concentric ankle inversion strength was assessed using an isokinetic dynamometer at an angular velocity of 60°/s. Peak torque was normalized to body weight and expressed as a percentage of body weight (PT/BW, %). Higher values indicate greater inversion torque relative to body weight.

  Baseline, Week 5, and Week 10

• Ankle Eversion Peak Torque Relative to Body Weight at 60°/s

  Concentric ankle eversion strength was assessed using an isokinetic dynamometer at an angular velocity of 60°/s. Peak torque was normalized to body weight and expressed as a percentage of body weight (PT/BW, %). Higher values indicate greater eversion torque relative to body weight.

  Baseline, Week 5, and Week 10

• Ankle Inversion Peak Torque Relative to Body Weight at 120°/s

  Concentric ankle inversion strength was assessed using an isokinetic dynamometer at an angular velocity of 120°/s. Peak torque was normalized to body weight and expressed as a percentage of body weight (PT/BW, %). Higher values indicate greater inversion torque relative to body weight.

  Baseline, Week 5, and Week 10

• Ankle Eversion Peak Torque Relative to Body Weight at 120°/s

  Concentric ankle eversion strength was assessed using an isokinetic dynamometer at an angular velocity of 120°/s. Peak torque was normalized to body weight and expressed as a percentage of body weight (PT/BW, %). Higher values indicate greater eversion torque relative to body weight.

  Baseline, Week 5, and Week 10

Other Outcomes (6)

• Knee Extension Test Range of Motion at 60°/s

  Baseline, Week 5, and Week 10

• Knee Flexion Test Range of Motion at 60°/s

  Baseline, Week 5, and Week 10

• Ankle Inversion Test Range of Motion at 60°/s

  Baseline, Week 5, and Week 10

Study Arms (2)

Water-Inertia-Based Unstable-Load Training

EXPERIMENTAL

Participants assigned to this arm completed a supervised 10-week dynamic stability training program three times per week while wearing an Aqua Vest with a total external load of 5 kg, consisting of approximately 4 kg of water and a 1-kg vest. The partially filled water pouches allowed internal water movement during exercise, creating a mobile external load. Exercise content, session duration, set-repetition structure, rest intervals, and any additional prescribed exercise loads were matched to the stable-load training arm.

Behavioral: Water-Inertia-Based Dynamic Stability Training

Stable-Load Training

ACTIVE COMPARATOR

Participants assigned to this arm completed the same supervised 10-week dynamic stability training program three times per week while wearing a mass-matched stable weighted vest with a total external load of 5 kg, consisting of approximately 4 kg of steel rods and a 1-kg vest. The steel rods were arranged to approximate the spatial loading configuration of the water pouches. Exercise content, session duration, set-repetition structure, rest intervals, and any additional prescribed exercise loads were matched to the unstable-load training arm.

Behavioral: Stable-Load Dynamic Stability Training

Interventions

Water-Inertia-Based Dynamic Stability Training BEHAVIORAL

Participants completed a supervised dynamic stability training program three times per week for 10 weeks (30 sessions), with each session lasting approximately 50 minutes. During training, participants wore a vest providing a total external load of 5 kg, consisting of approximately 4 kg of water in partially filled pouches and a 1-kg vest. Internal water movement allowed the external load distribution to change during exercise. Exercises were performed for three sets, with 12 repetitions per set during weeks 1-5 and 15 repetitions per set during weeks 6-10, with 30 seconds of rest between sets. Exercise content and any additional prescribed implement loads were matched to the stable-load intervention.

Also known as: Unstable-Load Training (ULT), Aqua Vest Training

Water-Inertia-Based Unstable-Load Training

Stable-Load Dynamic Stability Training BEHAVIORAL

Participants completed the same supervised dynamic stability training program three times per week for 10 weeks (30 sessions), with each session lasting approximately 50 minutes. During training, participants wore a stable weighted vest providing a total external load of 5 kg, consisting of approximately 4 kg of steel rods and a 1-kg vest. The steel rods were arranged to approximate the spatial loading configuration of the water pouches used in the water-inertia intervention. Exercises were performed for three sets, with 12 repetitions per set during weeks 1-5 and 15 repetitions per set during weeks 6-10, with 30 seconds of rest between sets. Exercise content and any additional prescribed implement loads were matched between groups.

Also known as: Stable-Load Training (SLT), Weighted Vest Training

Stable-Load Training

Eligibility Criteria

• Age: 19 Years - 25 Years
• Sex: female
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Female undergraduate students aged 19 to 25 years.
• Generally healthy at the time of enrollment.
• No surgery within the previous 6 months.
• No congenital, neurological, vestibular, or musculoskeletal disorder affecting the foot, pelvis, or spine.
• No participation in resistance training during the previous 12 months. Able and willing to participate in the 10-week supervised exercise intervention and study assessments.
• Provided written informed consent to participate.

You may not qualify if:

• Participated in resistance training or functional training outside the study intervention during the 10-week study period.
• Developed a health condition, injury, or other circumstance during the study that prevented safe participation in the prescribed exercise program or outcome assessments.

Sponsors & Collaborators

• Yuanyan Huang: lead

Study Sites (1)

Busan University of Foreign Studies

Busan, South Korea

Location

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: OUTCOMES ASSESSOR
• Purpose: OTHER
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR INVESTIGATOR
• PI Title: Lecturer

Study Record Dates

• First Submitted: September 4, 2026
• First Posted: September 10, 2026
• Study Start: July 5, 2024
• Primary Completion: September 20, 2024
• Study Completion: September 20, 2024
• Last Updated: September 14, 2026

Record last verified: 2026-09

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL
• Time Frame: Beginning after publication of the primary study results, with no predetermined end date.
• Access Criteria: De-identified individual participant data may be shared with qualified researchers upon reasonable request for scientifically appropriate purposes. Requests should include a brief research proposal and planned analyses and will be reviewed for ethical, privacy, and data-protection considerations. Approved data will be provided by the study investigator.

Locations

KR (1)