Effects of Mind-body Exercise on Cardiovascular Functions and Dual-tasking Performance in Chronic Stroke Survivors - a Randomized Controlled Clinical Trial

Previous studies have been showing a deterioration of dual-tasking performance among stroke survivors, especially when a dynamic physical task is involved. Dual-tasking performance has been associated with risk of fall among stroke survivors. Results of prior studies on investigating the effect of conventional exercise on dual-tasking performance in the population have not been reaching a consistent conclusion.

Apart from the ability to dual-tasking, cardiovascular functioning, such as increased arterial stiffness and dysfunction of the cardiac autonomic system, has also been found compromised in stroke survivors. Such deterioration has been related to increased cardiovascular risk and mortality. Research has been suggesting the beneficial effect of aerobic exercise with moderate or high intensity on improving both the arterial stiffness and autonomic functioning in healthy older adults.

Tai Chi is a Chinese traditional martial art and has been adopted as a rehabilitation exercise in recent decades. Tai Chi can be considered as a dual-tasking exercise as its practitioners should perform the physical movement, monitoring their action, and plan for the next Tai Chi form simultaneously. Besides, Tai Chi is an exercise with moderate intensity. It is also a mind-body exercise which emphasizes on maintaining a relaxed status of mind during the practice. The mental status can be achieved by its meditation feature, as well as synchronizing the Tai Chi movement with gentle, slow and deep breathing. The mind-body characteristics of Tai Chi were similar to those factors proposed to improve the functioning of the autonomic nervous system. Indeed, previous studies have been suggesting the beneficial effects of Tai Chi training on dual-tasking performance, arterial compliance, and autonomic regulation among healthy older adults. However, its effects on these functioning among stroke survivors have not yet been established.

Given the characteristics of Tai Chi and previous studies on its therapeutic effects among healthy older adults, the exercise may also benefit stroke survivors. This randomized controlled trial, therefore, is designed to investigate the effect of Tai Chi training on dual-tasking performance, arterial compliance, and functioning of the cardiac autonomic nervous system among stroke survivors. The investigators expected that these functions would be improved after Tai Chi training and the training effects would be better than those of the conventional exercise in stroke survivors. If Tai Chi is found beneficial to dual-tasking, vascular function, and autonomic regulation, the exercise may incorporate into the rehabilitation program.

Eligible subjects (please refer to the 'Eligibility' part for inclusion and exclusion criteria) were randomized into one of the three groups: Tai Chi, conventional exercise, or control (please refer to the 'Arms and Interventions' part for details of each group). The dual-tasking performance was assessed with three different physical tasks: turning-while-walking, stepping back, and stepping down. These physical tasks were included as they are common in daily life among community-dwelling stroke survivors but can also be challenging to them. Moreover, these activities were among the most prevalent reasons for fall among stroke survivors. Other assessment employed in this study can be found in the 'Outcome Measures' part. Assessment was conducted before, after, and one month after the intervention period.