Oyake K1,2, Momose K3, Baba Y2, Ito N2, Suda Y2, Murayama J2, Mochida A2, Kondo K2, Otaka Y2,4
1International University of Health and Welfare, School of Health Sciences at Narita, Department of Physical Therapy, Narita, Japan, 2Tokyo Bay Rehabilitation Hospital, Narashino, Japan, 3Shinshu Univerity, School of Health Sciences, Department of Physical Therapy, Matsumoto, Japan, 4Fujita Health University, School of Medicine, Department of Rehabilitation Medicine, Toyoake, Japan
Background: Post-stroke fatigue (PSF) is a common symptom for individuals with stroke. PSF may lead to reduced physical activity, thus causing physical deconditioning (Thilarajah et al., 2017). However, physiological responses during exercise in individuals with PSF have not been reported. Understanding physiological responses during exercise in individuals with PSF is essential for developing effective therapeutic strategies for PSF.
Purpose: We aimed to compare the physiological response during a graded exercise between individuals with and without PSF. We hypothesized that lower oxygen consumption during exercise would characterize individuals with PSF (Thilarajah et al., 2017).
Methods: Seventeen patients with stroke admitted to subacute rehabilitation ward between December 2017 and July 2018 was enrolled in the study (13 men, 60 ± 10 years of age, 67 ± 32 days poststroke; mean ± SD). PSF was defined as a mean of 9 items of the Fatigue Severity Scale score of 4 or more (Cumming et al., 2016). Participants performed a graded leg cycle exercise test. Physiological responses were measured using an expired gas analyzer (AT-1100, ANIMA) and an impedance cardiography (TFM-3040, CNSytems) simultaneously. After a 3-minute of rest, the exercise test began with a 3-minute warm-up at 0 W at a target cadence of 50 rpm, followed by progressive 10 W increases in work rate every minute. The exercise test was terminated according to the guidelines (ACSM, 2013). Physiological responses were defined as the changes in oxygen consumption, respiratory rate, tidal volume, heart rate, stroke volume, and arterial-venous oxygen difference from rest to peak exercise. In addition, ratings of perceived exertion (RPE, 6-20 scale) for both dyspnea and leg effort at the end of the test and peak work rate were measured. Age, sex, physiological responses, RPE, and peak work rate were compared between PSF and non-PSF groups using unpaired t-test, the Mann-Whitney U test, or Fisher's exact test, depending on the type of variable. Any p-values less than 0.05 were considered statistically significant.
Results: Nine participants (53%) had PSF. There were no significant differences in age and sex between PSF and non-PSF groups. The change in respiratory rate during exercise was significantly higher in PSF group (17 ± 7 breaths/min) than in non-PSF group (10 ± 5 breaths/min) (p = 0.02), while other physiological responses were not significantly different between groups. RPE for dyspnea was not significantly different between groups, while that for leg effort was significantly higher in PSF group (15 [15, 17]; median [interquartile range]) than in non-PSF group (14 [13, 15]) (p = 0.04). Peak work rate was not significantly different between groups.
Conclusion(s): The increase in respiratory rate during exercise and leg effort were significantly higher in PSF group than in non-PSF group, although other physiological responses and peak work rate were similar between groups. Respiratory rate is a stronger correlate of physical effort than other physiological variables (Nicolò et al., 2017), which may support our findings. In future studies, we will examine longitudinal relationship between PSF and physiological responses during exercise.
Implications: Our findings may be useful for developing effective therapeutic strategies for PSF.
Keywords: respiratory rate, exercise test, cardiovascular disease
Funding acknowledgements: This work was supported by a grant from the Funds for a Grant-in-Aid for Young Scientists to Kazuaki Oyake (18K17730).
Purpose: We aimed to compare the physiological response during a graded exercise between individuals with and without PSF. We hypothesized that lower oxygen consumption during exercise would characterize individuals with PSF (Thilarajah et al., 2017).
Methods: Seventeen patients with stroke admitted to subacute rehabilitation ward between December 2017 and July 2018 was enrolled in the study (13 men, 60 ± 10 years of age, 67 ± 32 days poststroke; mean ± SD). PSF was defined as a mean of 9 items of the Fatigue Severity Scale score of 4 or more (Cumming et al., 2016). Participants performed a graded leg cycle exercise test. Physiological responses were measured using an expired gas analyzer (AT-1100, ANIMA) and an impedance cardiography (TFM-3040, CNSytems) simultaneously. After a 3-minute of rest, the exercise test began with a 3-minute warm-up at 0 W at a target cadence of 50 rpm, followed by progressive 10 W increases in work rate every minute. The exercise test was terminated according to the guidelines (ACSM, 2013). Physiological responses were defined as the changes in oxygen consumption, respiratory rate, tidal volume, heart rate, stroke volume, and arterial-venous oxygen difference from rest to peak exercise. In addition, ratings of perceived exertion (RPE, 6-20 scale) for both dyspnea and leg effort at the end of the test and peak work rate were measured. Age, sex, physiological responses, RPE, and peak work rate were compared between PSF and non-PSF groups using unpaired t-test, the Mann-Whitney U test, or Fisher's exact test, depending on the type of variable. Any p-values less than 0.05 were considered statistically significant.
Results: Nine participants (53%) had PSF. There were no significant differences in age and sex between PSF and non-PSF groups. The change in respiratory rate during exercise was significantly higher in PSF group (17 ± 7 breaths/min) than in non-PSF group (10 ± 5 breaths/min) (p = 0.02), while other physiological responses were not significantly different between groups. RPE for dyspnea was not significantly different between groups, while that for leg effort was significantly higher in PSF group (15 [15, 17]; median [interquartile range]) than in non-PSF group (14 [13, 15]) (p = 0.04). Peak work rate was not significantly different between groups.
Conclusion(s): The increase in respiratory rate during exercise and leg effort were significantly higher in PSF group than in non-PSF group, although other physiological responses and peak work rate were similar between groups. Respiratory rate is a stronger correlate of physical effort than other physiological variables (Nicolò et al., 2017), which may support our findings. In future studies, we will examine longitudinal relationship between PSF and physiological responses during exercise.
Implications: Our findings may be useful for developing effective therapeutic strategies for PSF.
Keywords: respiratory rate, exercise test, cardiovascular disease
Funding acknowledgements: This work was supported by a grant from the Funds for a Grant-in-Aid for Young Scientists to Kazuaki Oyake (18K17730).
Topic: Neurology: stroke; Cardiorespiratory; Neurology
Ethics approval required: Yes
Institution: International University of Health and Welfare
Ethics committee: The ethics committee of International University of Health and Welfare
Ethics number: 17-Io-47
All authors, affiliations and abstracts have been published as submitted.
