This randomized controlled trial study aims to evaluate the feasibility and preliminary efficacy of a combined inspiratory muscle training (IMT) and blood flow restriction (BFR) intervention in frail older adults. Outcomes of interest include feasibility, physical function, respiratory muscle strength, handgrip strength, five-times sit-to-stand performance, body composition, frailty level, fall efficacy, blood pressure, and adverse events.
Community-dwelling adults aged 65 years and older who are classified as at least "vulnerable" using the Clinical Frailty Scale (score ≥4).
Participants must have no cognitive impairment and be able to follow commands, as assessed by the Mini-Mental State Examination (MMSE).
(1) are unable to participate in exercise (e.g., due to severe musculoskeletal disorders)
(2) have high-risk factors for exercise, such as uncontrolled hypertension (>150 mmHg systolic blood pressure (SBP) / >90 mmHg diastolic blood pressure (DBP), coagulation disorders, and deep venous thrombosis
(3) have hematological disorders or are using hematology related-medications
(4) have significant comorbidities, including a history of stroke, diabetes with severe complications, or cardiovascular diseases
Parallel
Exercise
BehavioralEach session will last approximately 60 minutes and will include three components: (1) an initial 3-minute IMT exercise performed at an intensity corresponding to rating of perceived exertion (RPE) 11-13 on the Borg 6-20 scale, (2) a 50-minute low-intensity exercise program combined with BFR, and (3) a second 3-minute IMT session at the same target intensity. For the IMT, the protocol follows a progressive intensity model, starting with 30% of the maximum inspiratory pressure (MIP) in Week 1 to allow participants to become familiar with the technique. The intensity will gradually increase to a target of 60% MIP by Week 6, based on the participants' tolerance. For the BFR, during weeks 1-2, participants will train at constant loads. From weeks 2-6, training loads will be increased. Cuff pressure will be prescribed relative to the calculated arterial occlusion pressure (AOP): 50% in weeks 1-2, 60% in weeks 3-4, and 70% in weeks 5-6 for both lower- and upper-body exercises.
Sham Control
BehavioralParticipants in the control group will perform the identical BFR exercise protocol as the intervention group. However, IMT will be delivered at 2% of MIP, which is considered a sham condition and has not been shown to improve respiratory muscle function. If the calculated load corresponding to 2% of a participant's baseline S-Index is below the minimum resistance permitted by the POWERbreathe K5, the device's minimum available load of 5 cmH₂O will be applied.
Recruitment rate
The recruitment rate will be calculated by dividing the number of recruited participants by the number of eligible participants
Attrition rate
Attrition rate is the proportion of randomized participants who withdraw from the study or are lost to follow-up before completing the final assessment.
Exercise Enjoyment
Enjoyment will be assessed using a single-item Exercise Enjoyment Scale, which asks participants, "How much did you enjoy the exercise session?). Responses are rated on a 7 Likert scale ranging from 1 (not at all) to 7 (extremely)
Short Physical Performance Battery (SPPB)
The SPPB consists of three components-standing balance, gait speed, and repeated chair stands-each scored from 0 to 4 and summed to a total score ranging from 0 (worst performance) to 12 (best performance). Lower SPPB scores indicate poorer physical function and a higher risk of adverse outcomes, with scores below 10 predictive of all-cause mortality in older adults.
Respiratory Muscle Strength
We will use the S-Index Test to evaluate the respiratory muscle function based on maximum dynamic inspiratory pressure, which is a recommended tool developed by POWERbreathe. Participants will be advised to avoid strenuous exercise for 24h and to rest in a sitting position for 15 minutes before the assessment. Then, they performed eight inspiratory maneuvers in a standing position, divided into three to four series of two to three repetitions.
Handgrip Strength
Handgrip strength will be evaluated to estimate the maximum upper-limb muscle function in older adults. Participants will be seated with the shoulder adducted, the elbow flexed to 90°, and the forearm and wrist in a neutral position. They will then be instructed to squeeze the dynamometer as forcefully as possible.
Five-times sit-to-stand
The five-times sit-to-stand test is simple to administer and has been widely applied in both clinical and research settings. Participants will sit with their backs against the chair and be instructed to stand and sit five times as quickly as possible.
Frailty level
The Clinical Frailty Scale (CFS) is a 9-point global clinical measure ranging from 1 (very fit) to 9 (terminally ill), used to classify frailty severity in older adults. A traditional Chinese version of the CFS has been validated in Taiwanese older adults, demonstrating acceptable inter-rater reliability and good criterion validity against established frailty measures
The Borg Rating of Perceived Exertion (RPE) Scale
The Borg RPE scale reflects an individual's subjective perception of exercise intensity, integrating sensations of physical effort, breathlessness, and fatigue. The scale ranges from 6 to 20, where 6 indicates "no exertion at all" and 20 indicates "maximal exertion." This RPE score will be assessed every training session
Automated Office Blood Pressure
Automated Office Blood Pressure will be monitored before and after intervention to minimize cardiovascular risks and ensure that timely medical assistance is available for participants who experience any discomfort. Upon arrival at the lab, participants will be asked to sit for at least 5 minutes before the first blood pressure reading; the average of two readings will be used for that visit
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Taipei Medical University
Lead sponsor
National Taiwan University
Collaborator
University of Texas at Austin
Collaborator
