Power Exercise for Stroke Recovery: The POWER Feasibility Trial (POWER-F)

Post-stroke deficits are highly common and functional impairment persists throughout life after stroke. Skeletal muscle mass and strength are fundamental contributors to mobility throughout the adult life course. Stroke-related muscle atrophy contributes to loss of strength, and declines in lower extremity function, cardiorespiratory fitness, and walking independence and post-stroke sarcopenia. Improving the quantity and function of skeletal muscle needs to be an important therapeutic target after stroke. Resistance exercise training (RET) has been shown to increase skeletal muscle mass, strength and power, reduce oxidative stress, improve cardiac function, and better regulate lipids after stroke. However, the feasibility and the effects of a power focused RET program for individuals with stroke need to be examined.

This study is a single-group, open label trial examining the feasibility and preliminary effect estimates of a 10-week power-focused exercise training program in people living with stroke. Fifteen participants with chronic stroke will participate in the exercise program 3 times per week for 10 weeks at a progressive intensity. The program will take place at a community exercise gym built for older adults and people with physical disabilities. Feasibility outcomes will be assessed throughout the trial. Effectiveness outcomes will be assessed at baseline and immediately post-intervention.

Single-group pilot trial aimed at examining the feasibility of a 10-week power-focused resistance training intervention for people with stroke

The program is intentionally designed with 3 progressive phases: Phase 1 Familiarization (Week 1) will allow participants to begin with a low-intensity version of the training program (body weight resisted or light weights at RPE 2-3 for 8 repetitions) to acclimate participants to the movements. Phase 2 Strength (Weeks 2-5) will progress in loads to achieve volitional fatigue between 5-8 repetitions (RPE 7-9). Phase 3 Power (Weeks 6-10) will use intensities between RPE 4-6 (15-20 repetitions) and execute each exercise at the highest possible velocity to focus on muscle power. The exercises, selected to emphasize functional movements relevant to daily activities.

Recruitment rates (n/week) and the number of recruited subjects (n) will be reported. Criteria for success include recruitment of ≥1 participant per month and n=15 recruited in ≤13 months.

Recruitment of males and females, men, women and gender diverse participants will be recorded (n, %). Criteria for success is <60% (n<9) of any sex or gender identity.

Percentage of sessions attended (%) and lost to follow-up (n) will be reported. Criteria for success includes ≥85% sessions attended and ≤10% (n<2) lost to follow-up.

Number of adverse events (i.e., deaths, serious and non-serious adverse events, n) will be reported. Criteria for success is 0 deaths or serious adverse events and <5 non-serious adverse events.

Adherence to the prescribed exercises (%) and abnormal blood pressure responses to exercise (n) will be recorded. Criteria for success includes ≥85 of participants performing ≥85% of sets at the prescribed intensity, and ≤25% of weeks experiencing ≥1 abnormal blood pressure response (SBP ≥210 or ≥190 for males and females, respectively).

Satisfaction will be measured with a 5-point Likert scale (1 = not at all satisfied, 2 = not satisfied, 3 = neither satisfied or not satisfied, 4 = satisfied, and 5 = completely satisfied). Criteria for success is ≥85% of participants reporting being satisfied or completely satisfied with the program.

The TUG is a measure of functional mobility. A standard chair (~46cm in height) will be placed at the start of a flat walking course and a cone will be placed 3 meters from the chair. Participants will stand from the chair, walk 3 meters, turn back towards the chair, and sit back down, without assistance. The task will be timed and measured in seconds.

The SPPB involves 3 tests, each measuring different constructs of physical function: (1) balance (tandem stand test), (2) walking ability (4-meter walk test), and (3) lower-limb strength and endurance (5-times sit to stand test). Two trained study staff members will concurrently assess each measure. Each test on the SPPB is scored separately on a scale ranging from 0 to 4, per instrument scoring guidelines. Raw and SPPB scores will be measured.

The 30sCST is a measure of lower extremity strength and endurance. A ~43cm chair with a straight back and no armrests will be placed against the wall. Participants will cross their arms and keep feet flat on the floor. With their back straight, stand up and sit down as many times as possible in 30 seconds.

Upper- and lower-extremity muscle power (Watts/kg) will be measured using an isokinetic dynamometer, bilaterally, at 3 different velocities (30º, 60º, 120º per second).

Upper- and lower-extremity muscle torque (Nm) will be measured using an isokinetic dynamometer, bilaterally, at 3 different velocities (30º, 60º, 120º per second).

Maximal isometric knee and elbow flexor and extensor strength (kg) and grip strength (kg) will also be measured, using a handheld dynamometer.

The global physical activity questionnaire (GPAQ) consists of 16 items, which are grouped to capture different domains of physical activities including work, transport and discretionary (i.e., leisure or recreational) activities. The GPAQ score may range from 0 to 80,640 MET-minutes per week, although the maximum value is likely not possible to be attained. Higher values indicate greater physical activity levels.

Version 3 of the Stroke-Impact Scale (SIS-3.0) will be used to assess stroke-specific health-related quality of life. The SIS-3.0 consists of 59 items that measure 8 different domains of health: strength, hand function, (instrumental) activities of daily living, mobility, communication, emotion, cognition, and participation. Each domain is scored separately and range from 0 to 100. Higher values indicate greater health-related quality of life.

Inclusion Criteria: ≥18 years old ≥6 months post-stroke Able to walk >10 meters with or without the use of an assistive device Living in the community Mild to moderate stroke severity (modified Rankin Scale ≤3) Exclusion Criteria: Any contraindications to exercise for people with cardiovascular disease, such as unstable angina, uncontrolled hypertension, orthostatic blood pressure with exercise, or uncontrolled arrhythmias Significant cognitive impairment that would preclude safe exercise participation (Montreal Cognitive Assessment score <26) Actively engaged in stroke rehabilitation services