Effectiveness of Therapeutic Exercise Combined With Respiratory Muscle Training in Patients With Subacute Stroke

Stroke has a significant impact on morbidity, mortality and healthcare expenditure globally. In addition to the motor and cognitive consequences, as well as on functional independence and social participation, it can produce alterations in the respiratory function. Scientific evidence supports the application of both therapeutic exercise programs and respiratory muscle training (RMT). However, studies that combine both interventions are limited, and to date no study has been published that examines the effectiveness of this combination in the subacute phase of stroke, which is the one that presents the widest range of neuroplasticity. Objectives: To analyze the effects of a combined therapeutic exercise and RMT program, compared to the therapeutic exercise and sham RMT program, on different variables related to functional, respiratory, swallowing and speech/voice capacity, in patients in the subacute phase of a stroke. Type of research: double-blind randomized controlled clinical trial. Design: The study will be carried out at the University Hospital Complex of A Coruña (CHUAC), where 64 patients with more than three and less than six months of evolution after a stroke will be recruited. Participants will be randomly assigned to two groups: the intervention group will perform a combined therapeutic exercise and RMT program, while the control group will combine the same therapeutic exercise program and sham RMT. The duration of the intervention will be eight weeks. The therapeutic exercise program will be carried out three days per week and will consist of a cardiovascular exercise part and a strength-endurance part. The RMT protocol will involve both the inspiratory and expiratory muscles, using the Orygen-Dual Valve® device. The control group will use the same valve but without resistance, generating a sham RMT. It will have a frequency of five days per week and will be carried out at the home of each patient. Additionally, half the subjects in the intervention group will continue the RMT protocol once the eight-week period has ended, with a frequency of two days per week, until the six-month follow-up. Possible differences between groups will be analyzed before and after the intervention, and at three and six months of follow-up, in relation to the following domains: functional capacity, functional independence, lung and respiratory muscle function, swallowing and speech/voice function, respiratory signs and symptoms, and quality of life.

This protocol is designed to analyze the effects of a therapeutic exercise program combined with an RMT protocol in patients with subacute stroke, compared to another group that will perform the therapeutic exercise program combined with sham RMT in relation to different functional variables.

Sample size assessment: The sample size calculation was performed using the G\*Power software and based on the 6 Minute Walk Test (6MWT), chosen as the main variable. The minimum clinically important difference (MCID) data from the study by Fulk et al. (MCID=130) and the standard deviation (SD) from the study by Baker et al. (conducted in patients with subacute stroke in the United Kingdom, SD=143) were used. For a two-sided hypothesis, with a statistical power of 90% and a significance level of 0.05, a sample size of 32 subjects per group would be required (assuming a 20% loss over the course of the study). Additionally, a pilot phase will be developed at the beginning of the study with eight other subjects who will not be part of the final sample, in order study the feasibility of the project.

Plan for missing data: At the end of each assessment session, all questionnaires will be checked to ensure they are complete and filled out correctly. If a participant does not attend a session, they will be phone called and rescheduled for that session. In cases where data are reported as missing, unavailable, or uninterpretable due to inconsistencies or out-of-range results, a plan will be implemented to manage these cases. Strategies will include imputing missing data and excluding cases.

Statistical analysis plan: Anaconda® software and the Python 3.8.8 programming language will be used. A descriptive analysis of the variables included in the study will be performed initially. For qualitative variables, absolute frequencies and percentages will be presented, and for quantitative variables, measures of central tendency (mean/median) and dispersion (range/standard deviation) will be presented, depending on whether they are normal or non-normal. The normality of the sample will be tested using the Shapiro-Wilk test. Per-protocol and intention-to-treat analyses will be performed to determine the effectiveness of the treatment both under ideal conditions of protocol adherence and in a more realistic context of losses throughout the intervention. To compare the results of the outcome measures between the study groups throughout the intervention, a repeated-measures ANOVA will be applied with a within-subject factor, time, which has four levels (pre-training, post-training, and at three and six months post-training), and a between-subject factor, the type of intervention (therapeutic exercise + RMT or therapeutic exercise + sham RMT). Another repeated-measures ANOVA will be applied with the same within-subject factor, and the presence or absence of maintenance sessions as a between-subject factor (only for the intervention group). The level of statistical significance will be set at p\<0.05.

Eligibility Criteria:
Inclusion Criteria

* Those diagnosed with a first stroke occurring three to six months after the onset (subacute phase).
* Those aged 18 years or older.
* Those able to walk at least 10 meters, with or without walking aids and/or physical assistance from another person.

Exclusion Criteria:

* Those with recurrent stroke.
* Those with a history of chronic respiratory disease.
* Those with other underlying neurological diseases with impaired functionality prior to the stroke.
* Those with other cardiovascular or metabolic diseases in an unstable phase.
* Those with severe cognitive deficits that impede understanding of the assessment tests and/or the intervention.
* Those with severe facial paralysis that impedes proper performance of pulmonary function and respiratory muscle strength tests.
* Those with a prior participation in a RMT program.
* Those who participate in a cardiovascular and/or strength-endurance training program at the time of the study.
* Those with any of the contraindications to performing the tests included in the study protocol: spirometry, respiratory muscle strength and endurance tests, and 6MWT.
* Those with any of the contraindications to physical exercise.