Evaluation of three measures of cardiorespiratory fitness in independently ambulant stroke survivors

Exploring Alternative Measurements of Cardiorespiratory Fitness in Patients With Mild Ischemic Stroke at Acute Phase

Background

While emerging studies have suggested an association of cardiorespiratory fitness (CRF) with stroke risk and overall health outcomes, little is known regarding the optimum methods of CRF measurement in patients with mild acute ischemic stroke.

Objective

The aim of this study was to explore the association between the 6-min walk distance (6MWD) and other measurements related to CRF in patients with mild ischemic stroke at the acute stage.

Methods

A total of 30 patients with stroke and 71 healthy subjects matched for age and grip strength (GS) were prospectively recruited. All patients were within 14 days after stroke onset and presented mild motor impairment (with a full score of Fugl-Meyer Motor Assessment). Demographic data of both groups and clinical information of the stroke group were documented, and the CRF comparison between the two groups was conducted. Each participant underwent a one-time assessment of 6MWD and a series of measurements related to CRF, including GS, 10-m walk test (10mWT), five-times sit-to-stand time (FTSST), functional reaching test (FRT), Berg Balance Scale (BBS), and waistline. Pearson's product-moment correlation coefficient test and multiple linear regression were performed to explore the indicators of CRF.

Results

Significant moderate correlations (0.3 < r <0.6) were found between 6MWD and GS of left hand (GS-left) (r = 0.573, p = 0.001), GS of right hand (GS-right) (r = 0.524, p = 0.003), FTSST (r = −0.551, p = 0.002), 10mWT (r = 0.554, p = 0.001), and FRT (r = 0.449, p = 0.021) in the patient group. While 6MWD displayed significant moderate correlations with waistline (r = 0.364, p = 0.002), 10mWT (r = 0.512, p < 0.001), FTSST (r = −0.573, p < 0.001), and FRT (r = 0.550, p < 0.001) in the healthy group. All these dependent variables were entered into a stepwise multiple linear regression analysis to evaluate their values in estimating CRF as measured by 6MWD in each group. Analyses suggested that GS-left (p = 0.002) and FTSST (p = 0.003) were the indicators of CRF in the patient group with stroke and explained 51.4% of the variance of 6MWD (R² = 0.514); FTSST (p < 0.001), 10mWT (p < 0.001), and FRT (p = 0.021) were the indicators of CRF in the healthy group and explained 58.9% of variance of 6MWD (R² = 0.589).

Conclusions

Our data confirmed that CRF is impaired in patients with mild ischemic stroke at the acute phase. Moreover, GS-left may be an optional indicator of CRF in patients with mild acute ischemic stroke, but not in healthy people.

Clinical Trial Registration

www.chictr.org.cn, identifier: ChiCTR2000031379.

The Determination of Step Frequency in 3-min Incremental Step-in-Place Tests for Predicting Maximal Oxygen Uptake from Heart Rate Response in Taiwanese Adults

The maximal oxygen uptake (VO_2max) prediction models established by step tests are often used for evaluating cardiorespiratory fitness (CRF). However, it is unclear which type of stepping frequency sequence is more suitable for the public to assess the CRF. Therefore, the main purpose of this study was to test the effectiveness of two 3-min incremental step-in-place (3MISP) tests (i.e., 3MISP_30s and 3MISP_60s) with the same total number of steps but different step-frequency sequences in predicting VO_2max. In this cross-sectional study, a total of 200 healthy adults in Taiwan completed 3MISP_30s and 3MISP_60s tests, as well as cardiopulmonary exercise testing. The 3MISP_30s and 3MISP_60s models were established through multiple stepwise regression analysis by gender, age, percent body fat, and 3MISP-heart rate. The statistical analysis included Pearson's correlations, the standard errors of estimate, the predicted residual error sum of squares, and the Bland-Altman plot to compare the measured VO_2max values and those estimated. The results of the study showed that the exercise intensity of the 3MISP_30s test was higher than that of the 3MISP_60s test (% heart rate reserve (HRR) during 3MISP_30s vs. %HRR during 3MISP_60s = 81.00% vs. 76.81%, p < 0.001). Both the 3MISP_30s model and the 3MISP_60s model explained 64.4% of VO_2max, and the standard errors of the estimates were 4.2043 and 4.2090 mL·kg^-1·min^-1, respectively. The cross-validation results also indicated that the measured VO_2max values and those predicted by the 3MISP_30s and 3MISP_60s models were highly correlated (3MISP_30s model: r = 0.804, 3MISP_60s model: r = 0.807, both p < 0.001). There was no significant difference between the measured VO_2max values and those predicted by the 3MISP_30s and 3MISP_60s models in the testing group (p > 0.05). The results of the study showed that when the 3MISP_60s test was used, the exercise intensity was significantly reduced, but the predictive effectiveness of VO_2max did not change. We concluded that the 3MISP_60s test was physiologically less stressful than the 3MISP_30s test, and it could be a better choice for CRF evaluation.

Assessment for cardiovascular fitness in patients with stroke: which cardiopulmonary exercise testing method is better?

Background: Assessment for cardiovascular disease (CVD) is important in stroke patients, both being one of the main factors limiting success in stroke rehabilitation and its increased risk in stroke patients. Reduced exercise capacity after stroke decreases patients' functionality and further increases the risk of CVD. Carefully selected cardiopulmonary exercise testing (CPET) can be safely used to determine the risk of CVD and to prescribe exercise program in stroke rehabilitation.Objectives: The primary purpose of this study is to determine the most appropriate CPET in patients with stroke. The secondary aim is to determine the relationship between cardiorespiratory fitness and functional status of the patients.Methods: Two CPETs using treadmill and bicycle ergometer protocols determined with a preliminary study were performed on participants. The main outcome measure was VO_2peak. Patients were also evaluated according to Brunnstrom motor staging, Modified Ashworth Scale, Berg Balance Scale, and Functional Independence Measure.Results: In total, 38 patients reached higher VO_2peak values at treadmill test compared to bicycle test (p < 0.001). The mean VO₂peak reached at treadmill CPET was 62% of the control group where mean VO_2peak reached at bicycle was 76% of the control group. No significant correlation was found between Brunnstrom staging, spasticity, Berg Balance Scale, and VO_2peak .Discussion: The results of this study indicate that CPET can be performed safely in stroke patients when appropriate protocol was selected and that treadmill was more appropriate to determine cardiorespiratory fitness in this study population.

Guidelines for the Evaluation of Cardiorespiratory Physiotherapy in Stroke Patients

Evaluation of stroke patients is prioritized over therapeutic interventions to restore cardiorespiratory capacity. This study aimed to develop a clinically applicable guideline to evaluate cardiorespiratory physiotherapy in stroke patients based on a literature review and a modified Delphi survey. The literature search included 13,498 articles in PubMed, EMBASE, CINAHL, and Cochrane Library electronic databases. We surveyed previous articles between January 2010 and June 2019. After the option elimination process, a total of 27 documents were selected and analyzed (draft: 18, modified Delphi survey: 9). The results of this research are roughly divided into two categories. First, 31 draft items were extracted, and a modified Delphi survey questionnaire was created from a literature review. Second, an expert was asked to make two modified Delphi surveys and to modify, delete, and supplement the entries in the statistical analysis at each level to finalize the steps to 20 items. The guidelines developed in this study reflect the selective use of cardiorespiratory physiotherapy evaluation methods in the clinical setting, based on the health status of individual patients. Moreover, the guidelines may help physiotherapists make informed decisions based on expert knowledge, thereby playing a crucial role in the patient-centered treatment planning process.

Noninvasive investigation of the cardiodynamic response to 6MWT in people after stroke using impedance cardiography

This is a cross-section observational study that investigated the cardiodynamic response to a 6-minute walk test (6MWT) in patients after stroke using impedance cardiography (ICG). Patients diagnosed with stroke were invited to participate in a 6MWT on consecutive days. Heart rate (HR), cardiac output (CO), stroke volume (SV) and cardiac index (CI) were measured by ICG using the PhysioFlow^® PF07 Enduro^TM at 1-second intervals for 10 minutes prior to, during and for 10 minutes after each 6MWT. Oxygen saturation, perceived exertion score (modified Borg scale) and the distance covered at the end of each 6MWT were recorded. Twenty-nine patients (mean age 55.6±10.9 years) completed the study. The mean duration of stroke after diagnosis was 14.4±19.1 months. There were no differences in the measured data between the first and second 6MWT (mean intraclass correlation coefficient (ICC) range: 0.87–0.95). The 6 minute walk distance (6WMD) covered in the two 6MWTs was 246±126 and 255±130m respectively (p>0.05). Mean measured data for each subject at rest, and at the end of the better performed 6MWT were, respectively: HR 78±11 and 100±18 bpm; CO 5.5±1.2 and 8.9±2.6 l/min, SV 71.3±16 and 89.3±18.6 ml/beat and CI 3.0±0.6 and 4.9±1.3 l/min/m². After commencement of the 6MWT, the increase in SV took 30 sec before the rise approaching a plateau, whereas HR, CO and CI continued to rise steeply for 90 sec before leveling off to a steady rise. After completion of the 6MWT, all parameters had returned to baseline by a mean of 3.5 min. Sub-group analysis showed that the increase in cardiac output was predominantly contributed by an increase in heart rate in participants diagnosed with stroke for less than 1 year, whereas both stroke volume and heart rate contributed similarly to the increase in cardiac output in participants with diagnosis of stroke for longer than 1 year. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) both returned to baseline within 2 minutes post 6MWT. HR recorded at the end of the 6MWT was 60.8±10.6% of the predicted maximal heart rate and perceived exertion score was 5±2. Correlations between 6MWD and HR, and between 6MWD and SV were weak, with correlation coefficients Spearman’s rho (r_s) =0.46, and 0.42, respectively (p<0.05). Correlation between 6MWD and CO and CI were higher (r_s= 0.66 and 0.63, respectively (p<0.01)). This is the first study to report cardiac responses during a 6MWT in stroke patients. ICG is a reliable, non-invasive, repeatable method of measuring cardiodynamic data in stroke patients.

What Is the Dose-Response Relationship Between Exercise and Cardiorespiratory Fitness After Stroke? A Systematic Review

BACKGROUND

Exercise after stroke improves cardiorespiratory fitness and walking capacity; however, the effect of altering exercise dose (via frequency, intensity, time, and type) on fitness or walking capacity is unclear.

PURPOSE

The purpose of this study was to synthesize the current evidence for the effects of different doses of exercise on cardiorespiratory fitness and walking capacity in people after stroke.

DATA SOURCES

Seven relevant electronic databases were searched using keywords relating to stroke and cardiorespiratory fitness.

STUDY SELECTION

Trials that compared more than 1 dose of exercise for people (≥ 18 years old) after stroke and measured peak oxygen consumption or 6-minute walk test distance as an outcome were included. Two reviewers independently appraised all trials.

DATA EXTRACTION

Two reviewers independently extracted data from included articles. Intervention variables were extracted in accordance with the Template for Intervention Description and Replication checklist.

DATA SYNTHESIS

Data were synthesized narratively. Nine trials involving 279 participants were included. Three of 5 trials comparing exercise intensity showed that higher-intensity training was associated with greater improvements in cardiorespiratory fitness. The effects of other exercise dose components (frequency, time, and type) on fitness were not determined. Overall, walking capacity improved as program length increased.

LIMITATIONS

All trials had a high risk of bias, and most had a high rate of attrition. Most trials included people more than 6 months after stroke and who walked independently, limiting the generalizability of the findings.

CONCLUSIONS

Exercising at an intensity greater than 70% of heart rate reserve can be more effective in increasing cardiorespiratory fitness after stroke than exercising at lower intensities. More trials that compare exercise doses by manipulating only 1 dose parameter at a time for people after stroke are needed.