Exercise Intensity Matters in Stroke Rehabilitation

Exercise Intensity Matters: An Opportunity to Promote Neurorecovery and Cardiovascular Health in Stroke

McMaster University, Jewish Rehabilitation Hospital, Ontario Stroke Network, Canadian Institutes of Health Research (CIHR)

The main objective of this multi-site project is to compare the effects of 12 weeks of HIIT vs. MICT on brain plasticity. The effects of HIIT vs. MICT on cardiovascular health, psychosocial predictors of physical activity and motor function will also be compared. HIIT and MICT will be delivered through a whole-body exercise paradigm using a recumbent stepper that requires arm and leg forces. Outcomes will be assessed at baseline (T0, 0 weeks), at the end of the intervention (T1, 12 weeks) and at 8-week follow-up (T2, 20 weeks).

Background: Stroke is a major health issue in Canada, with 405,000 Canadians currently living with stroke. Exercise is an important component of stroke rehabilitation that can result in improved function and health. Traditionally, exercise rehabilitation programs for stroke employ moderate-intensity continuous training (MICT) protocols that are typically sustained for 20-30 minutes. The continuous nature of this form of training however, even at moderate intensities, is challenging for many individuals with stroke to sustain due to neuromotor impairments and poor exercise capacity. High-intensity exercise, when delivered in short interval bursts (i.e. high-intensity interval training, HIIT), may be a feasible alternative that allows higher intensities to be achieved during exercise. This is important because intensity of training is the critical factor in promoting changes in neuroplasticity and cardiovascular health, the two most important aspects of recovery and secondary prevention after stroke. Interventions implemented earlier following stroke are generally viewed to yield greater benefits, but high intensity exercise may also promote neuroplasticity and optimize cardiovascular health in later stages of recovery. Furthermore, determining if HIIT is viewed to be motivating and enjoyable for individuals post-stroke can provide insight into the sustainability of this intervention. Objective: To compare the effects of 12 weeks of HIIT and MICT on neuroplasticity, cardiovascular health and psychosocial predictors of physical activity in individuals with chronic stroke. Design: Participants will be recruited from two research sites and randomly allocated into HIIT or MICT. Participants will be assessed before and after the training period, and at an 8-week follow-up. Outcomes: 1) The investigators will assess: Neuroplasticity: by measuring markers of corticospinal excitability at rest and in response to a non-invasive brain stimulation protocol applied over the primary motor cortex (M1); 2) Cardiovascular health: by measuring cardiorespiratory fitness, resting blood pressure, arterial stiffness, and waist-hip ratio; 3) Psychosocial predictors of physical activity: by measuring exercise motivation and enjoyment. Methods: Neuroplasticity: motor evoked potentials amplitude, intracortical facilitation and short-intracortical inhibition on the lesioned and unlesioned upper limb M1 area at rest and in response to continuous theta-burst will be measured with transcranial magnetic stimulation; Cardiovascular health: cardiorespiratory fitness will be measured with a graded exercise test, resting blood pressure with an automated blood pressure monitor and arterial stiffness using applanation tonometry. Exercise motivation and enjoyment will be assessed with the Physical Activity Enjoyment Scale and the Behavioral Regulation Exercise Questionnaire-3, respectively. Expected results: Both HIIT and MICT will result in improvements in outcomes of neuroplasticity and cardiovascular health. However, improvements with HIIT will be greater and will last longer. Participants will rate HIIT as enjoyable as MICT, and motivation for exercise will increase similarly after both interventions. Impact: HIIT is a promising, time-efficient, and potentially more effective alternative to traditional MICT protocols that could offer an opportunity for greater improvement in motor recovery and cardiovascular health in people living with stroke.

Stroke, Rehabilitation, Neurosciences, Exercise, Neurorecovery, Cardiovascular health, High-intensity interval training, Moderate-intensity continuous training

Intensity will be determined using a combination of heart rate reserve (HRR, calculated as HRR= [max HR - resting HR] x [% training] + [resting HR]) and ratings of perceived exertion (RPE). The protocol will involve 10 60-second intervals of high intensity interspersed with 9 60-second low-intensity intervals. The initial high intensity intervals will start at 80% of the HRR (RPE=14-17) and progress by 10% every 4 weeks. Low intensity intervals will be performed at 30% of HRR (RPE=9-11). Three-minute warm-up and 2-minute cool-down periods will be performed at 30% of HRR. Total HIIT time including warm-up and cool-down is 24 minutes.

Intensity will be determined using a combination of heart rate reserve (HRR, calculated as HRR= [max HR - resting HR] x [% training] + [resting HR]) and ratings of perceived exertion (RPE). The MICT protocol will be increased using a progression schedule previously used (initial intensity at 40% HRR (RPE=9-11), and progressed by 10% HRR every 4 weeks up to 60% HRR (RPE=13-14) will be maintained until the end of the intervention). A 3-minute warm-up and 2-minute cool-down will be performed at 30% HRR (RPE=9-11). The total duration of MICT, including warm-up and cool-down, will be 35 minutes.

Ratio of waist circumference measured at the level of the umbilicus, and hip circumference taken at the level of the greater trochanters.

The Physical Activity Enjoyment Scale. Each item is scored 1-7 (1=does not make me happy, 7=makes me happy), yielding a total between 8 and 56.

The Behavioral Regulation Exercise Questionnaire-3. 24 items using a 5-point Likert scale (0=Not true for me, 4=Very true for me).

A motor task that requires modulating hand-grasping force. The goal is to apply force, move the cursor, and reach targets displayed on the screen as accurately as possible.

Inclusion Criteria: 6-60 months following first-ever, single stroke confirmed by MRI/CT Living in the community and able to independently walk at least 10 meters (assistive devices permitted, as this is representative of many people who regain some walking ability following stroke but commonly with some adaptation) Montreal Cognitive Assessment score >20 (individuals with this score are capable to follow exercise instructions) Exclusion Criteria: Significant disability as determined by modified Rankin scale score <2 Stroke of non-cardiogenic origin or tumor Actively engaged in stroke rehabilitation services or a structured exercise program besides the one provided in the study Class C or D American Heart Association Risk Criteria Other neurological or musculoskeletal co-morbidities that preclude exercise participation Pain which is worsened with exercise Cognitive, communication, or behavioral issues that would limit safe exercise participation Contraindications to transcranial magnetic stimulation.

Rodrigues L, Moncion K, Eng JJ, Noguchi KS, Wiley E, de Las Heras B, Sweet SN, Fung J, MacKay-Lyons M, Nelson AJ, Medeiros D, Crozier J, Thiel A, Tang A, Roig M. Intensity matters: protocol for a randomized controlled trial exercise intervention for individuals with chronic stroke. Trials. 2022 May 24;23(1):442. doi: 10.1186/s13063-022-06359-w.