Autonomic Function, Body Composition, Post Menopausal, Resistance Exercise
Conditions
Keywords
Electrical Muscle Stimulation, Resistance Training, Exercise, Lower Body, Neuromuscular Electrical Stimulation
Brief summary
This pilot randomized controlled trial evaluates whether combining lower-body electrical muscle stimulation (EMS) with resistance training is feasible and beneficial for physically inactive postmenopausal women, who experience concurrent declines in muscle strength, body composition, arterial elasticity, and cardiac autonomic balance. Sixteen physically inactive postmenopausal women aged 50-70 years are randomly assigned (1:1) to either (A) supervised resistance training combined with lower-body EMS (applied to 6 muscle groups: lower back, lower abdomen, glutes, quadriceps, hamstrings, and calves) or (B) supervised resistance training alone. Both groups complete twelve 50-minute sessions (consisting of a 10-minute warm-up, 30-minute main exercise, and a 10-minute cool-down) over 6 weeks (twice weekly). Assessments before and after the intervention include body composition, lower-body muscle function, arterial stiffness, and 5-minute heart rate variability. The primary aim is to determine the feasibility of the protocol(recruitment, retention, session attendance, and intervention dose delivery) to inform a future definitive trial. Preliminary estimates of intervention effects on the measured outcomes are reported as secondary aims.
Detailed description
BACKGROUND AND RATIONALE Postmenopausal women often experience physiological declines in muscle function, body composition, and cardiovascular health. While resistance training is an established countermeasure, maximizing its efficiency and adherence remains a challenge. Applying lower-body electrical muscle stimulation (EMS) during resistance training may enhance physiological adaptations and overall training effectiveness. This study aims to evaluate the feasibility of combining lower-body EMS with resistance training in physically inactive postmenopausal women to inform the design of a future definitive trial. STUDY DESIGN This is a pilot randomized controlled trial. Participants will be randomly assigned to either an intervention group receiving combined lower-body EMS and resistance training or a control group receiving resistance training alone. Clinical and physiological outcomes will be assessed before and after the intervention period to evaluate preliminary effects. PRIMARY FEASIBILITY OUTCOMES The primary objective is to evaluate the feasibility of the study protocol. Feasibility will be determined by assessing several key components, including: Recruitment: The ability to recruit the target population within the planned timeframe. Retention: The proportion of participants who complete the study and post-intervention assessments. Adherence: Participant attendance and compliance with the scheduled exercise sessions. Intervention Fidelity: The successful delivery of the exercise intensity and EMS protocol as intended. These components will be evaluated against pre-established progression criteria to determine whether the protocol can proceed to a larger trial or requires modification. STATISTICAL APPROACH Feasibility outcomes will be summarized primarily using descriptive statistics. For secondary physiological and clinical outcomes, appropriate statistical methods will be utilized to estimate the preliminary effects of the intervention, comparing changes between the groups while adjusting for baseline measurements. Effect sizes and confidence intervals will be calculated to provide preliminary evidence and to assist with sample size calculations for future large-scale trials.
Interventions
DEVICELower-Body EMS combined with Resistance Training
Electrical muscle stimulation (85 Hz, 350 μs, cycle 11, duty approx 1:2) applied to 6 muscle groups: lower back (erector spinae), lower abdomen, glutes, quadriceps, hamstrings, and calves.
BEHAVIORALResistance Training
A 50-minute session consisting of a 10-minute warm-up, 30 minutes of main exercise (8 machine-based lower-body resistance exercises, 3 sets of 8-12 repetitions), and a 10-minute cool-down.
Sponsors
Seoul National University
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
OTHER
Masking
SINGLE (Outcomes Assessor)
Eligibility
Sex/Gender
FEMALE
Age
50 Years to 70 Years
Healthy volunteers
Yes
Inclusion criteria
* Women aged 50 to 70 years. * Menopause for at least 1 year with no current menstruation. * Physically inactive (have not participated in resistance training more than twice a week for the past 6 months)
Exclusion criteria
* Currently receiving hormone replacement therapy (HRT). * Presence of implanted electrical medical devices. * Severe or uncontrolled medical conditions. * Any surgery within the past 6 months. * Acute illness with fever, infection, or active inflammation. * Severe peripheral arterial disease or abdominal/inguinal hernia. * Severe psychiatric disorders requiring medication, or current substance abuse. * Deemed physically or mentally unfit to participate in the exercise program by the investigator.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Composite Feasibility Outcome (Recruitment, Retention, Session Attendance, and Intervention Dose Delivery) | Baseline and Week 6 | The primary outcome is the feasibility of the study protocol, assessed via recruitment rates, participant retention, session adherence, and targeted intervention delivery. These indicators will be evaluated against pre-defined progression criteria using descriptive statistics to determine whether to proceed with or modify the protocol for a future definitive trial. Unit: Percentage |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Skeletal Muscle Mass Index (SMI) | Baseline and Week 6 | Appendicular skeletal muscle mass divided by height squared. Unit: kg/m². |
| Total Body Muscle Mass | Baseline and Week 6 | Total skeletal muscle mass of the whole body. Unit: kg |
| Total Leg Muscle Mass | Baseline and Week 6 | Combined left and right leg skeletal muscle mass. Unit: kg |
| Body Fat Percentage | Baseline and Week 6 | Body fat mass expressed as a percentage of total body weight. Unit: % |
| Total Body Fat Mass | Baseline and Week 6 | Absolute total body fat in kilograms. Unit: kg |
| Estimated Visceral Fat Area (eVFA) | Baseline and Week 6 | Estimated visceral fat area at the umbilical level. Unit: cm² |
| Waist Circumference | Baseline and Week 6 | Circumference measured at the level of the umbilicus. Unit: cm |
| Waist-to-Hip Ratio (WHR) | Baseline and Week 6 | Waist circumference divided by hip circumference. Unit: ratio |
| Body Mass Index (BMI) | Baseline and Week 6 | Body weight in kilograms divided by the square of height in meters. Unit: kg/m² |
| Phase Angle | Baseline and Week 6 | Whole-body bioimpedance phase angle derived from the arctangent of the reactance-to-resistance ratio. Marker of cellular membrane integrity and overall nutritional/health status. Unit: degrees |
| Dominant Knee Extensor Peak Torque per Body Weight at 60°/s | Baseline and Week 6 | Peak concentric knee extensor torque normalized to body weight, measured at 60°/sec angular velocity on the dominant limb. Unit: Nm/kg |
| Non-dominant Knee Extensor Peak Torque per Body Weight at 60°/s | Baseline and Week 6 | Peak concentric knee extensor torque normalized to body weight at 60°/sec on the non-dominant limb. Unit: Nm/kg |
| Dominant Knee Flexor Peak Torque per Body Weight at 60°/s | Baseline and Week 6 | Peak concentric knee flexor (hamstring) torque normalized to body weight at 60°/sec on the dominant limb. Unit: Nm/kg |
| Non-dominant Knee Flexor Peak Torque per Body Weight at 60°/s | Baseline and Week 6 | Peak concentric knee flexor torque normalized to body weight at 60°/sec on the non-dominant limb. Unit: Nm/kg |
| Dominant Hamstring-to-Quadriceps (H/Q) Ratio at 60°/s | Baseline and Week 6 | Ratio of knee flexor peak torque to knee extensor peak torque at 60°/sec on the dominant limb. Unit: ratio |
| Non-dominant Hamstring-to-Quadriceps (H/Q) Ratio at 60°/s | Baseline and Week 6 | Ratio of knee flexor peak torque to knee extensor peak torque at 60°/sec on the non-dominant limb. Unit: ratio |
| Dominant Total Work Done by Knee Extensor per Body Weight at 180°/s | Baseline and Week 6 | Total work performed by knee extensors across the test set, normalized to body weight, at 180°/sec angular velocity on the dominant limb. Unit: Nm/kg |
| Non-dominant Total Work Done by Knee Extensor per Body Weight at 180°/s | Baseline and Week 6 | Total work performed by knee extensors normalized to body weight at 180°/sec on the non-dominant limb. Unit: Nm/kg |
| Dominant Total Work Done by Knee Flexor per Body Weight at 180°/s | Baseline and Week 6 | Total work performed by knee flexors normalized to body weight at 180°/sec on the dominant limb. Unit: Nm/kg |
| Non-dominant Total Work Done by Knee Flexor per Body Weight at 180°/s | Baseline and Week 6 | Total work performed by knee flexors normalized to body weight at 180°/sec on the non-dominant limb. Unit: Nm/kg |
| Average Brachial-Ankle Pulse Wave Velocity (baPWV) | Baseline and Week 6 | Mean of left and right brachial-ankle pulse wave velocity; primary indicator of large-artery stiffness. Unit: cm/s |
| Highest Brachial-Ankle Pulse Wave Velocity (baPWV) | Baseline and Week 6 | The higher of left and right baPWV values, reflecting the most affected limb. Unit: cm/s |
| Brachial Systolic Blood Pressure (SBP) | Baseline and Week 6 | Brachial systolic blood pressure. Unit: mmHg |
| Brachial Diastolic Blood Pressure (DBP) | Baseline and Week 6 | Brachial diastolic blood pressure. Unit: mmHg |
| Pulse Pressure (PP) | Baseline and Week 6 | Pulse pressure calculated as systolic minus diastolic blood pressure. Unit: mmHg |
| Mean Arterial Pressure (MAP) | Baseline and Week 6 | Mean arterial pressure derived from systolic and diastolic blood pressure. Unit: mmHg |
| Average Ankle-Brachial Index (ABI) | Baseline and Week 6 | Mean of left and right ankle-brachial systolic blood pressure ratio. Unit: ratio |
| Augmentation Index (AI) | Baseline and Week 6 | Augmentation index derived from second-derivative photoplethysmography. Unit: unitless |
| Root Mean Square of Successive Differences (RMSSD) | Baseline and Week 6 | Root mean square of successive differences between adjacent normal-to-normal RR intervals. Unit: ms |
| High-Frequency (HF) Power | Baseline and Week 6 | Spectral power in the high-frequency band (0.15-0.4 Hz); index of parasympathetic (vagal) activity. Unit: ms² |
| Standard Deviation of NN Intervals (SDNN) | Baseline and Week 6 | Standard deviation of all normal-to-normal RR intervals; time-domain index of overall heart rate variability. Unit: ms |
| Low-Frequency (LF) Power | Baseline and Week 6 | Spectral power in the low-frequency band (0.04-0.15 Hz). Unit: ms² |
| LF/HF Ratio | Baseline and Week 6 | Ratio of low-frequency to high-frequency spectral power. Unit: ratio |
| High-Frequency Normalized Units (HFnu) | Baseline and Week 6 | HF power expressed in normalized units = HF / (LF + HF) × 100. Unit: n.u. |
| Low-Frequency Normalized Units (LFnu) | Baseline and Week 6 | LF power expressed in normalized units = LF / (LF + HF) × 100. Unit: n.u. |
| Total Power (TP) | Baseline and Week 6 | Total spectral power up to 0.4 Hz. Unit: ms² |
| Very-Low-Frequency (VLF) Power | Baseline and Week 6 | Spectral power in the very-low-frequency band (≤0.04 Hz). Unit: ms² |
Countries
South Korea
Contacts
PRINCIPAL_INVESTIGATORYeon Soo Kim, MD, Prof
Seoul National University
Outcome results
None listed