Feasibility and Effects of Inspiratory Muscle Training Combined With Blood Flow Restriction for Frail Older Adults

The recruitment rate will be calculated by dividing the number of recruited participants by the number of eligible participants

Attrition rate is the proportion of randomized participants who withdraw from the study or are lost to follow-up before completing the final assessment.

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)

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.

The 6MWT will be used to assess functional exercise capacity. Participants will be instructed to walk as far as possible along a flat, straight course for 6 minutes, and the total distance is recorded.

The TUG test is used to assess functional mobility, balance, and fall risk in older adults, incorporating a series of dynamic activities. Participants will be instructed to rise from a chair, walk three meters at a comfortable pace, turn around, walk back to the chair, and sit down. The total time taken to complete the task is recorded, with longer times indicating poorer functional mobility and higher fall risk

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 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.

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.

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 short form of the Falls Efficacy Scale-International (FES-I) includes 7 items rated on a 4-point Likert scale from 1 (not at all concerned) to 4 (very concerned). The total score ranges from 7 to 28, with higher values indicating greater concern about falling

The study team will record adverse events during the intervention caused by the exercise, including falls, fractures, exercise-related pain, dizziness, muscle strain, sprains, respiratory and cardiac adverse events, and hospitalization.

Fat mass will be assessed using a body composition analyzer and recorded in kilograms

Fat-free mass will be assessed using a body composition analyzer and recorded in kilograms.

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 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