Chronic obstructive pulmonary disease (COPD) is an irreversible disorder characterized by persistent airflow limitation and increased lung compliance. It leads to dyspnea, skeletal muscle dysfunction, impaired functional capacity, and reduced quality of life. Physical inactivity is considered a major contributor to symptom deterioration, the development of a vicious cycle, and ultimately increased mortality. According to the American College of Sports Medicine (ACSM), the American Thoracic Society (ATS), and the American Association of Cardiovascular and Pulmonary Rehabilitation (AACVPR), pulmonary rehabilitation should include aerobic and resistance exercise for at least 20 minutes per session, performed three to five times per week for a minimum of 12 weeks. Exercise intensity should be progressively increased to exceed 60% of peak oxygen uptake (VO₂peak), and patients are encouraged to maintain long-term exercise habits. However, there is still no consensus regarding the optimal initial intensity, progression strategy, and exercise duration. Previous studies have demonstrated that whole-body vibration (WBV) can improve lower extremity muscle strength, functional capacity, and quality of life in patients with COPD. However, its effects on lung function and the optimal training dose remain unclear. In addition, COPD also affects respiratory muscles, upper extremity strength and flexibility, as well as cardiac autonomic function. Therefore, the aim of this study is to investigate the effects of different WBV frequencies on lung function, respiratory muscle function, upper extremity strength and flexibility, and cardiac autonomic function, in order to determine the optimal training dose.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
NONE
Enrollment
102
All participants will receive three different frequencies of WBV (15, 25, and 35 Hz) in a block-randomized order, with a washout period of at least 7 days between conditions. Subsequently, participants will undergo three additional sessions at the final randomized frequency over one week to evaluate the cumulative effects.
National Cheng Kung University Hospital
Tainan, Taiwan
RECRUITINGPulmonary function test
Pulmonary function test is examined by spirometry, which measures the ability to inhale and exhale air over time. The results include forced vital capacity (FVC in L), forced exploratory volume in the first second (FEV1 in L), and the FVC/FEV1 ratio.
Time frame: Changes from baseline (week 0) to the three WBV frequency conditions (weeks 1-3) and the cumulative effects after three additional sessions at the final randomized frequency (week 6) will be assessed.
Diaphragm excursion and thickness
Diaphragm excursion (unit: mm) and thickness (unit: mm) are examined by diaphragmatic ultrasound when a participant performs maximal inspiration and expiration.
Time frame: Changes from baseline (week 0) to the three WBV frequency conditions (weeks 1-3) and the cumulative effects after three additional sessions at the final randomized frequency (week 6) will be assessed.
Respiratory muscle strength
Respiratory muscle strength is measured using a manometer, which records both maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) in cmH₂O
Time frame: Changes from baseline (week 0) to the three WBV frequency conditions (weeks 1-3) and the cumulative effects after three additional sessions at the final randomized frequency (week 6) will be assessed.
cardiopulmonary response
A cardiopulmonary exercise test collects gases (including measures of oxygen consumption, carbon dioxide production in ml/kg/min) and records heart rate (beat/min), which can be used to estimate cardiopulmonary response.
Time frame: Changes from baseline (week 0) to the three WBV frequency conditions (weeks 1-3) and the cumulative effects after three additional sessions at the final randomized frequency (week 6) will be assessed.
Upper limb muscle strength
Maximal voluntary contraction of upper limbs muscles. (unit: N)
Time frame: Changes from baseline (week 0) to the three WBV frequency conditions (weeks 1-3) and the cumulative effects after three additional sessions at the final randomized frequency (week 6) will be assessed.
Handgrip strength
Maximal voluntary handgrip strength. (unit: N)
Time frame: Changes from baseline (week 0) to the three WBV frequency conditions (weeks 1-3) and the cumulative effects after three additional sessions at the final randomized frequency (week 6) will be assessed.
Upper limb flexibility
Flexibility is examined by scratch test (unit: cm)
Time frame: Changes from baseline (week 0) to the three WBV frequency conditions (weeks 1-3) and the cumulative effects after three additional sessions at the final randomized frequency (week 6) will be assessed.
Heart rate variability (Standard Deviation of Normal-to Normal intervals, SDNN)
Heart rate variability (HRV) is examined to assess the automatic nervous system. Standard deviation of normal-to-normal (SDNN in ms) reflects overall heart rate variability and automatic function
Time frame: Changes from baseline (week 0) to the three WBV frequency conditions (weeks 1-3) and the cumulative effects after three additional sessions at the final randomized frequency (week 6) will be assessed.
Heart rate variability (Root mean square of successive differences, RMSSD)
Root mean square of successive differences (RMSSD in ms) represents short-term HRV and parasympathetic activity
Time frame: Changes from baseline (week 0) to the three WBV frequency conditions (weeks 1-3) and the cumulative effects after three additional sessions at the final randomized frequency (week 6) will be assessed.
Heart rate variability (Low frequency, LF)
Low frequency power (LF in ms2) reflects both sympathetic and parasympathetic modulation.
Time frame: Changes from baseline (week 0) to the three WBV frequency conditions (weeks 1-3) and the cumulative effects after three additional sessions at the final randomized frequency (week 6) will be assessed.
Heart rate variability (High frequency power, HF)
High frequency power (HF in ms2) reflects parasympathetic (vagal) activity.
Time frame: Changes from baseline (week 0) to the three WBV frequency conditions (weeks 1-3) and the cumulative effects after three additional sessions at the final randomized frequency (week 6) will be assessed.
Heart rate variability (LF/HF ratio)
LF/HF ratio represents sympathovagal balance.
Time frame: Changes from baseline (week 0) to the three WBV frequency conditions (weeks 1-3) and the cumulative effects after three additional sessions at the final randomized frequency (week 6) will be assessed.
St. George's Respiratory Questionnaire (SGRQ)
The St. George's Respiratory Questionnaire (SGRQ) is a standardized self-administered tool designed to measure the impact of chronic respiratory diseases, such as COPD and asthma, on a patient's health-related quality of life. It consists of 50 items divided into three domains-Symptoms, Activity, and Impacts-with scores ranging from 0 to 100, where a higher score indicates greater impairment. In clinical research and practice, a decrease of 4 points is typically recognized as the Minimal Clinically Important Difference (MCID), signifying a meaningful improvement in the patient's well-being.
Time frame: Changes from baseline (week 0) to the three WBV frequency conditions (weeks 1-3) and the cumulative effects after three additional sessions at the final randomized frequency (week 6) will be assessed.
COPD Assessment Test (CAT)
The COPD Assessment Test (CAT) is a concise, 8-item self-administered questionnaire designed to provide a simple and reliable measure of the health status of patients with Chronic Obstructive Pulmonary Disease (COPD). Unlike more complex tools, it evaluates a broad range of symptoms-including cough, phlegm, chest tightness, breathlessness, activity limitation, confidence, sleep, and energy levels-using a 6-point scale (0-5) for each item. The total score ranges from 0 to 40, where a score of 10 or higher typically indicates a significant impact of the disease on daily life, making it a highly practical instrument for routine clinical monitoring and patient management.
Time frame: Changes from baseline (week 0) to the three WBV frequency conditions (weeks 1-3) and the cumulative effects after three additional sessions at the final randomized frequency (week 6) will be assessed.
Fatigue Severity Scale (FSS)
The fatigue severity scale (FSS) is a 7-point scale questionnaire that measures the patients's level of fatigue. It contains 9 questions, and a total score of 36 points or higher indicates that the patient may be experiencing clinically significant fatigue and requires further evaluation.
Time frame: Changes from baseline (week 0) to the three WBV frequency conditions (weeks 1-3) and the cumulative effects after three additional sessions at the final randomized frequency (week 6) will be assessed.
Modified Medical Research Council (mMRC)
The modified medical research council (mMRC) dyspnea scale consists of 4 levels that describe respiratory difficulty during daily activities, higher levels indicate more severe symptoms
Time frame: Changes from baseline (week 0) to the three WBV frequency conditions (weeks 1-3) and the cumulative effects after three additional sessions at the final randomized frequency (week 6) will be assessed.
Short Form-36 (SF-36)
The short form-36 (SF-36) measures physical and social health status, with higher scores representing better overall health
Time frame: Changes from baseline (week 0) to the three WBV frequency conditions (weeks 1-3) and the cumulative effects after three additional sessions at the final randomized frequency (week 6) will be assessed.
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