ABILITY OF THE CARDIORESPIRATORY SYSTEM TO ADAPT TO EXERCISE IS IMPAIRED IN INDIVIDUALS WITH SEVERE POST-STROKE FATIGUE

K. Oyake1,2, Y. Baba2, Y. Suda2, J. Murayama2, A. Mochida2, Y. Ito2, H. Abe2, K. Kondo2, Y. Otaka2,3, K. Momose1
1Shinshu University, Department of Physical Therapy, School of Health Sciences, Matsumoto, Japan, 2Tokyo Bay Rehabilitation Hospital, Department of Rehabilitation Medicine, Narashino, Japan, 3Fujita Health University, Department of Rehabilitation Medicine I, School of Medicine, Toyoake, Japan

Background: Physical deconditioning after stroke may induce post-stroke fatigue. Although post-stroke fatigue relates to various clinical variables such as depressive symptoms and functional disability, there is limited evidence regarding an association between post-stroke fatigue and cardiorespiratory fitness variables such as oxygen consumption (VO2) at peak exercise and VO2 kinetics at the onset of exercise. VO2 kinetics has been shown to be more sensitive than VO2 at peak exercise for assessing changes in cardiorespiratory fitness. Therefore, we hypothesize that the severity of post-stroke fatigue could associate more strongly with VO2 kinetics than VO2 at peak exercise.

Purpose: This study aimed to examine whether patients with more severe fatigue exhibited a slower VO2 kinetics rather than a lower VO2 at peak exercise. Additionally, we examined the association between impaired cardiorespiratory responses and fatigue severity.

Methods: Thirty patients with subacute stroke participated in this study (22 males, 59.0 ± 10.0 years of age, 74.3 ± 33.1 days post stroke). Post-stroke fatigue was assessed using the Fatigue Severity Scale (FSS). A higher FSS score indicated more severe fatigue. In addition, we assessed clinical variables such as depressive symptoms and functional disability. Participants performed a symptom-limited graded exercise test to assess cardiorespiratory parameters at peak exercise and ventilatory inefficiency during exercise (oxygen uptake efficiency slope). In addition, a submaximal constant-load exercise test was conducted to assess the kinetics of cardiorespiratory variables. VO2 and ventilatory inefficiency were measured using an expired gas analyzer (Aerosonic AT-1100). Cardiac output was measured using a noninvasive impedance cardiography device (TFM-3040i). We examined whether the FSS score related to clinical and cardiorespiratory variables using the Spearman’s rank correlation coefficient and the Wilcoxon rank sum test based on variable types. If there were clinical variables that associated with the FSS score, partial Spearman’s rank correlation analysis was used to investigate the relationships between the FSS score and cardiorespiratory variables, after adjusting for potentially confounding variables.

Results: Although 30 participants underwent assessment of post-stroke fatigue and other clinical variables, 28 and 2 participants completed and refused, respectively, the exercise tests. The median FSS score was 33.50 (interquartile range = 27.75, 45.25). In five of 28 participants, cardiorespiratory data during the submaximal constant-load exercise test could not be measured because of technical difficulties. A higher FSS score significantly associated with a slower VO2 kinetics (rho = 0.530, p = 0.009), but not a lower VO2 at peak exercise (rho = −0.369, p = 0.053). In addition, post-stroke fatigue significantly related to ventilatory inefficiency during exercise (rho = −0.431, p = 0.022) and cardiac output kinetics (rho = 0.476, p = 0.022). There were no potentially confounding variables for the associations between the FSS score and cardiorespiratory variables.

Conclusion(s): The ability of the cardiorespiratory system to adapt to exercise is impaired in patients with severe post-stroke fatigue.

Implications: Patients with severe post-stroke fatigue may need to improve VO2 kinetics. Our findings can contribute to the development of an appropriate rehabilitation program for patients with post-stroke fatigue.

Funding, acknowledgements: This work was supported by a grant from the Funds for a Grant-in-Aid for Young Scientists to Kazuaki Oyake (18K17730).

Keywords: cerebrovascular accident, exercise test, Fatigue Severity Scale

Topic: Neurology: stroke

Did this work require ethics approval? Yes
Institution: Shinshu University
Committee: The Ethical Committee of Shinshu University School of Medicine
Ethics number: 3813


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