Heart rate asymmetry and emotional response to robot-assist task challenges in post-stroke patients

The level of motivation or stress influences learning the use of a robot-assist device for walking. Heart rate asymmetry (HRA) indicates the level of parasympathetic (HRA<0.5) and sympathetic (HRA>0.5) involvement in heart rate regulation. Three patients and seven controls were presented increasing levels of task difficulty. During training patients showed an increase in stress as indicated by the HRA index (0.524±0.02) in contrast to control participants (0.485±0.03). As the task complexity increased, the HRA in the patient group was atypical and falling below 0.5, compared to control (HRA>0.5). The latter result reflects an increased cognitive involvement and a higher sympathetic predominance in accordance with an increased task difficulty. Thus stroke affected the response to the task challenges in that the patient response to increasing task challenge leads to an inversion of HRA associated with a decreased mental engagement and higher risk of sudden cardiac death.