High Intensity Interval Training (HIIT) vs Heart Rate Variability (HRV) Training for Cardiac and Functional Rehabilitation After Stroke

Consequences of stroke are manyfold but all of them are important factors on the long-term outcomes of rehabilitation, becoming an important health problem with requires health strategies with advanced age. High intensity interval training (HIIT) is an efficient training protocol used in cardiac rehabilitation programs, but owing to the inter-individual variability in physiological responses to training associated to cardiovascular diseases, the exercise dose received by each patient should be closely controlled and individualized to ensure the safety and efficiency of the exercise program. The heart rate variability (HRV) is actually being used for this purpose, as it is closely linked to de parasympathetic nervous system activation. In this way, higher scores in HRV are associated with a good cardiovascular adaptation. The objective of this protocol is to determine the effect of HIIT compared with HRV-guided training on cardiorespiratory fitness, heart rate variability, functional parameters, body composition, quality of life, inflammatory markers, cognitive function, and feasibility, safety and adherence in patients after stroke undertaking an 8-week cardiac rehabilitation program. This will be a cluster-randomized controlled protocol in which patients after stroke will be assigned to an HRV-based training group (HRV-G) or a HIIT-based training group (HIIT-G). HIIT-G will train according to a predefined training program. HRV-G training will depend on the patients' daily HRV. The peak oxygen uptake (VO2peak), endothelial and work parameters, the heart rate variability, the functional parameters, the relative weight and body fat distribution, the quality of life, the inflammatory markers, the cognitive function, and the exercise adherence, feasibility and safety will be considered as the outcomes. It is expected that this HRV-guided training protocol will improve functional performance in the patients after stroke, being more safe, feasible and generating more adherence than HIIT, providing a better strategy to optimize the cardiac rehabilitation interventions.