Prescribing Aerobic Exercise Intensity without a Cardiopulmonary Exercise Test Post Stroke: Utility of the Six-Minute Walk Test

Effect of High-Intensity Interval Training and Moderate-Intensity Continuous Training in People With Poststroke Gait Dysfunction: A Randomized Clinical Trial

BACKGROUND

The exercise strategy that yields the greatest improvement in both cardiorespiratory fitness (V ̇ O 2 peak $$ \dot{\mathrm{V}}{\mathrm{O}}_{2\mathrm{peak}} $$ ) and walking capacity poststroke has not been determined. This study aimed to determine whether conventional moderate-intensity continuous training (MICT) or high-intensity interval training (HIIT) have different effects on V ̇ O 2 peak $$ \dot{\mathrm{V}}{\mathrm{O}}_{2\mathrm{peak}} $$ and 6-minute walk distance (6MWD).

METHODS AND RESULTS

In this 24-week superiority trial, people with poststroke gait dysfunction were randomized to MICT (5 days/week) or HIIT (3 days/week with 2 days/week of MICT). MICT trained to target intensity at the ventilatory anaerobic threshold. HIIT trained at the maximal tolerable treadmill speed/grade using a novel program of 2 work-to-recovery protocols: 30:60 and 120:180 seconds. V̇O2 and heart rate was measured during performance of the exercise that was prescribed at 8 and 24 weeks for treatment fidelity. Main outcomes were change in V ̇ O 2 peak $$ \dot{\mathrm{V}}{\mathrm{O}}_{2\mathrm{peak}} $$ and 6MWD. Assessors were blinded to the treatment group for V ̇ O 2 peak $$ \dot{\mathrm{V}}{\mathrm{O}}_{2\mathrm{peak}} $$ but not 6MWD. Secondary outcomes were change in ventilatory anaerobic threshold, cognition, gait-economy, 10-meter gait-velocity, balance, stair-climb performance, strength, and quality-of-life. Among 47 participants randomized to either MICT (n=23) or HIIT (n=24) (mean age, 62±11 years; 81% men), 96% completed training. In intention-to-treat analysis, change in V ̇ O 2 peak $$ \dot{\mathrm{V}}{\mathrm{O}}_{2\mathrm{peak}} $$ for MICT versus HIIT was 2.4±2.7 versus 5.7±3.1 mL·kg-1·min-1 (mean difference, 3.2 [95% CI, 1.5-4.8]; P<0.001), and change in 6MWD was 70.9±44.3 versus 83.4±53.6 m (mean difference, 12.5 [95% CI, -17 to 42]; P=0.401). HIIT had greater improvement in ventilatory anaerobic threshold (mean difference, 2.07 mL·kg-1·min-1 [95% CI, 0.59-3.6]; P=0.008). No other between-group differences were observed. During V̇O2 monitoring at 8 and 24 weeks, MICT reached 84±14% to 87±18% of V ̇ O 2 peak $$ \dot{\mathrm{V}}{\mathrm{O}}_{2\mathrm{peak}} $$ while HIIT reached 101±22% to 112±14% of V ̇ O 2 peak $$ \dot{\mathrm{V}}{\mathrm{O}}_{2\mathrm{peak}} $$ (during peak bouts).

CONCLUSIONS

HIIT resulted in more than a 2-fold greater and clinically important change in V ̇ O 2 peak $$ \dot{\mathrm{V}}{\mathrm{O}}_{2\mathrm{peak}} $$ than MICT. Training to target (ventilatory anaerobic threshold) during MICT resulted in ~3 times the minimal clinically important difference in 6MWD, which was similar to HIIT. These findings show proof of concept that HIIT yields greater improvements in cardiorespiratory fitness than conventional MICT in appropriately screened individuals.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03006731.

Muscle oxygenation of the paretic and nonparetic legs during and after exercise in chronic stroke: Implications for mobility

BACKGROUND

Oxygen delivery and demand are reduced in the paretic leg of individuals after stroke. However, it is unknown how muscle oxygenation, the balance between delivery and utilization of oxygen at the muscle, is altered post-stroke during aerobic exercise and how it relates to mobility.

OBJECTIVE

To monitor muscle oxygenation changes between the paretic and nonparetic legs of individuals after stroke during treadmill exercise and the 6-minute walk test and analyze the association with mobility.

DESIGN

Cross-sectional study.

SETTING

Cardiac rehabilitation program.

PATIENTS

Eleven male participants were enrolled in the study. Ten men (30.8 ± 4.1 months post-stroke; age 63.9 ± 13.9 years) with hemiparetic gait pattern finished the study.

METHODS OR INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Muscle oxygenation was measured with near-infrared spectroscopy placed on the vastus lateralis of each leg during treadmill exercise at the first ventilatory threshold and during a 6-minute walk test.

RESULTS

The desaturation slope during treadmill exercise was significantly steeper (p = .047) in the paretic (-0.7 ± 0.6%/s) compared to the nonparetic leg (-0.3 ± 0.2%/s). There was no other significant difference between legs. The 6-minute walk test distance was not correlated with 6-minute walk test muscle oxygenation in either leg (paretic: r = 0.20, p = 0.590; nonparetic: r = 0.42, p = .232).

CONCLUSIONS

At the onset of treadmill exercise, the paretic leg was unable to effectively match the oxygen demand and extraction of the nonparetic leg, suggesting the need for an immediate cardiovascular warmup prior to initiating moderate intensity exercise in this population. Because the exercise desaturation rate is thought to indicate increased anaerobic metabolism and lactate production, efforts to delay rapid desaturation could improve the sustainability of activities of daily living and exercise.

Reference equations for the six-minute walking distance in obese Chinese subjects more than 40 years old

BACKGROUND

Studies have shown that the reference equations for the six-minute walking distance (6MWD), which were mainly derived from healthy, normal-weight people, are not suitable for individuals with obesity. The main purpose of this study was to establish reference equations for the 6MWD in obese Chinese subjects.

METHODS

In our study, a total of 214 individuals with obesity performed the six-minute walking tests (6MWTs) according to the American thoracic society (ATS) guidelines, and the longer 6MWD was used for further analysis. The reference equations for the 6MWD were developed using stepwise multiple regression analysis. The newly established equations for the 6MWD were compared to the existing prediction equations.

RESULTS

The mean 6MWD for the cohort was 523 ± 56 m. We found that the reliability of two 6MWTs was good. Age and BMI were identified as independent factors, and explained 31% and 27% of the variance in the 6MWD for the male and female participants, respectively. Thus, the reference equations reported in the previous studies did not accurately predict the 6MWD in our subjects.

CONCLUSION

Our study was the first to describe the 6MWD in obese Chinese subjects and to propose new predictive equations. These established equations can improve the assessment of the health of obese Chinese patients whose exercise capacity is affected by the disease.

LEVEL OF EVIDENCE

III, Cohort study.

Associations Between Time After Stroke and Exercise Training Outcomes: A Meta-Regression Analysis

Background Knowledge gaps exist regarding the effect of time elapsed after stroke on the effectiveness of exercise training interventions, offering incomplete guidance to clinicians. Methods and Results To determine the associations between time after stroke and 6-minute walk distance, 10-meter walk time, cardiorespiratory fitness and balance (Berg Balance Scale score [BBS]) in exercise training interventions, relevant studies in post-stroke populations were identified by systematic review. Time after stroke as continuous or dichotomized (≤3 months versus >3 months, and ≤6 months versus >6 months) variables and weighted mean differences in postintervention outcomes were examined in meta-regression analyses adjusted for study baseline mean values (pre-post comparisons) or baseline mean values and baseline control-intervention differences (controlled comparisons). Secondary models were adjusted additionally for mean age, sex, and aerobic exercise intensity, dose, and modality. We included 148 studies. Earlier exercise training initiation was associated with larger pre-post differences in mobility; studies initiated ≤3 months versus >3 months after stroke were associated with larger differences (weighted mean differences [95% confidence interval]) in 6-minute walk distance (36.3 meters; 95% CI, 14.2-58.5), comfortable 10-meter walk time (0.13 m/s; 95% CI, 0.06-0.19) and fast 10-meter walk time (0.16 m/s; 95% CI, 0.03-0.3), in fully adjusted models. Initiation ≤3 months versus >3 months was not associated with cardiorespiratory fitness but was associated with a higher but not clinically important Berg Balance Scale score difference (2.9 points; 95% CI, 0.41-5.5). In exercise training versus control studies, initiation ≤3 months was associated with a greater difference in only postintervention 6-minute walk distance (baseline-adjusted 27.3 meters; 95% CI, 6.1-48.5; fully adjusted, 24.9 meters; 95% CI, 0.82-49.1; a similar association was seen for ≤6 months versus >6 months after stroke (fully adjusted, 26.6 meters; 95% CI, 2.6-50.6). Conclusions There may be a clinically meaningful benefit to mobility outcomes when exercise is initiated within 3 months and up to 6 months after stroke.

Feasibility, reproducibility and validity of the 10 meter Shuttle Test in mild to moderately impaired people with stroke

Background

There currently is no field test available for measuring maximal exercise capacity in people with stroke.

Objective

To determine the feasibility, reproducibility and validity of the Shuttle Test (ST) to measure exercise capacity in people with stroke.

Design

Longitudinal study design.

Setting

Rehabilitation department, day care centres from a nursing home and private practices specialized in neuro rehabilitation.

Subjects

People with subacute or chronic stroke.

Interventions

A standardized protocol was used to determine feasibility, reproducibility and validity of the 10-meter Shuttle Test (10mST).

Main measures

Number of shuttles completed, 1^stVentilatory Threshold (1^stVT).

Results

The associations of the number of shuttles completed and cardiopulmonary capacity as measured with a portable gas analyser were r > 0.7, confirming good convergent validity in subacute and chronic people with stroke. Criterion validity, however, indicates it is not a valid test for measuring maximal cardiopulmonary capacity (VO_2max). Only 60% of participants were able to reach the 1^stVT. Higher cardiopulmonary capacity and a higher total score of the lower extremity Motricity Index contributed significantly to a higher number of shuttles walked (p = 0.001).

Conclusions

The Shuttle Test may be a safe and useful exercise test for people after stroke, but may not be appropriate for use with people who walk slower than 2 km/h or 0.56 m/s.

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.

Exercise Prescription Guidelines for Cardiovascular Disease Patients in the Absence of a Baseline Stress Test

Aerobic exercise is a core component of cardiac rehabilitation (CR). Leading organizations recommend that the exercise prescriptions should be based on a symptom limited baseline graded exercise test (GXT). However, recent evidence suggests that only ~30% of CR clinics perform baseline GXTs. Consequently, exercise prescriptions including exercise progression in CR are not following standard exercise prescription guidelines. Therefore, the purpose of this review is to provide clinicians with evidence-based techniques for prescribing exercise in the absence of a baseline GXT. Intensity indicators (e.g., heart rate, perceived exertion) are reviewed, along with special exercise considerations for various disease states (e.g., heart failure, peripheral artery disease, and coronary artery disease). Baseline exercise testing remains the gold standard approach for prescribing exercise among heart disease patients, however, clinicians must be prepared to safely develop and monitor patients when a baseline GXT is not performed.

The 2-minute walk test is not a valid method to determine aerobic capacity in persons with Multiple Sclerosis

BACKGROUND:

Walking tests, like the 2-minute fast walk test, are simple, inexpensive performance-based tests, and therefore seem attractive to estimate the aerobic fitness in people with chronic diseases.

OBJECTIVE:

To determine the criterion validity of the 2-minute fast walk test for estimating aerobic capacity in patients with Multiple Sclerosis (MS), by comparing it with the peak oxygen uptake (VO2peak in mL/kg/min) as measured by Cardiopulmonary Exercise Testing (CPET) on a cycle ergometer.

METHODS:

The 2 min fast walk test was performed on a marked indoor trajectory, using a static start protocol. Aerobic capacity (VO2peak, in mL/kg/min) was derived from CPET on a cycle ergometer. Criterion validity was tested by means of Pearson’s correlation coefficient and should be at least 0.70 for a good criterion validity of the 2 min walk test. Linear regression analysis was applied to more precisely estimate VO2peak.

RESULTS:

In total 141 people with severe MS-related fatigue (mean age 47.0 years (range 23–68 years), 73% women, median disease duration 7.8 years (range 0.3 – 28.7 years)) performed both tests. The distance walked in two minutes ranged from 52.0 to 290.0 m (mean 175.1 m, sd 44.9 m), while the VO2peak varied between 11.31 and 40.28 mL/kg/min (mean 22.52 mL/kg/min, sd 6.07 mL/kg/min). The correlation between the 2 min walk test and VO2peak was 0.441 (95% CI: 0.309–0.570). The absolute residual error in estimated VO2peak was 5.47 mL/kg/min.

CONCLUSIONS:

Due to the poor correlation found between the 2 min walk test and VO2peak, the 2-min walk test cannot be recommended as a valid alternative for estimating aerobic capacity in persons with MS.

Aerobic Training and Mobilization Early Post-stroke: Cautions and Considerations

Knowledge gaps exist in how we implement aerobic exercise programs during the early phases post-stroke. Therefore, the objective of this review was to provide evidence-based guidelines for pre-participation screening, mobilization, and aerobic exercise training in the hyper-acute and acute phases post-stroke. In reviewing the literature to determine safe timelines of when to initiate exercise and mobilization we considered the following factors: arterial blood pressure dysregulation, cardiac complications, blood-brain barrier disruption, hemorrhagic stroke transformation, and ischemic penumbra viability. These stroke-related impairments could intensify with inappropriate mobilization/aerobic exercise, hence we deemed the integrity of cerebral autoregulation to be an essential physiological consideration to protect the brain when progressing exercise intensity. Pre-participation screening criteria are proposed and countermeasures to protect the brain from potentially adverse circulatory effects before, during, and following mobilization/exercise sessions are introduced. For example, prolonged periods of standing and static postures before and after mobilization/aerobic exercise may elicit blood pooling and/or trigger coagulation cascades and/or cerebral hypoperfusion. Countermeasures such as avoiding prolonged standing or incorporating periodic lower limb movement to activate the venous muscle pump could counteract blood pooling after an exercise session, minimize activation of the coagulation cascade, and mitigate potential cerebral hypoperfusion. We discuss patient safety in light of the complex nature of stroke presentations (i.e., type, severity, and etiology), medical history, comorbidities such as diabetes, cardiac manifestations, medications, and complications such as anemia and dehydration. The guidelines are easily incorporated into the care model, are low-risk, and use minimal resources. These and other strategies represent opportunities for improving the safety of the activity regimen offered to those in the early phases post-stroke. The timeline for initiating and progressing exercise/mobilization parameters are contingent on recovery stages both from neurobiological and cardiovascular perspectives, which to this point have not been specifically considered in practice. This review includes tailored exercise and mobilization prescription strategies and precautions that are not resource intensive and prioritize safety in stroke recovery.

Aerobic Training in Canadian Stroke Rehabilitation Programs

BACKGROUND AND PURPOSE

Aerobic training (AT) is recommended for people after stroke, yet uptake and operationalization of AT in clinical practice in Canada have not been measured. We surveyed inclusion of structured AT and barriers to implementation in public inpatient/outpatient stroke rehabilitation programs across Canada.

METHODS

A Web-based questionnaire was sent to 89 stroke rehabilitation program leads.

RESULTS

Forty-six programs from 7 of 9 eligible Canadian provinces/territories completed the questionnaire. Seventy-eight percent of programs reported including AT, with most (75%) excluding participants with severe physical impairments, and 28% excluding those with coexisting cardiac conditions. A greater proportion of dedicated stroke rehabilitation programs prescribed AT, compared to nondedicated stroke units (68.8% vs 31.3%, P = 0.02). The top 2 challenges for programs that included and did not include AT were "insufficient time within therapy sessions" and "length of stay in rehabilitation." Programs that did not include AT ranked "not a goal of most patients" and "not an organizational/program priority" as third and fourth, whereas they were ranked eighth and thirteenth by programs with AT. Best practice recommendations were inconsistently followed for conducting preparticipation exercise testing (36.1%) and for monitoring patients from higher-risk populations, specifically people with diabetes at risk for hypoglycemia (78.8%) and hypertension (36.6%). Of programs conducting preparticipation exercise testing, 91% did not monitor electrocardiography.

DISCUSSION AND CONCLUSIONS

Most stroke rehabilitation programs across Canada include AT. People with severe physical impairment and those with cardiac, metabolic, and hemodynamic comorbidities may be excluded or not appropriately monitored during exercise. More detailed guidelines and training practices are needed to address these challenges.Video Abstract available for more insights from the authors (see Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A233).

[Utility of the 6-minute walk test in assessing maintenance of physical activity after cardiac rehabilitation]

Evaluation of therapeutic patient education (TPE) is an integral part of cardiac rehabilitation programs. An important component of this involves assessing continued physical activity (PA) after rehabilitation. Few tools are available to assess the maintenance of physical activity, and we argue that use of a field test like the 6-minute walk test (6MWT) can provide some useful indicators. Objective: to study the utility of the 6MWT as a tool for assessing maintenance of PA in post-rehabilitation follow-up. Methods: we conducted a retrospective study of 168 patients (133 men and 35 women) with a mean age of 60.65 years (+/-9.7). First, we analyzed the data from a stress test (ST) and a 6MWT at the beginning and end of rehabilitation. We then analyzed the data from a 6MWT and an International Physical Activity Questionnaire (IPAQ) performed six months after the end of rehabilitation. Results: there was a significant correlation between the 6MWT and the initial and final ST (r=0.5456, p<0.001 for the initial ST, r= 0.604, p<0.001 for the final ST), confirming the validity of using this test in cardiac rehabilitation. We observed a slight correlation between the 6MWT and the IPAQ (r=0.3923, p<0.001) six months post-rehabilitation. The IPAQ results show that patients with a significant level of physical activity during the week maintain their 6MWT distance. Conclusion: the 6MWT is a reliable test in cardiac rehabilitation. It can be used in conjunction with the IPAQ to assess patient adherence to physical activity guidelines in post-rehabilitation follow-up.

Cardiopulmonary Responses During Clinical and Laboratory Gait Assessments in People With Chronic Stroke

Background

The 6-Minute Walk Test (6MWT) is a common clinical assessment used to evaluate locomotor function in patients after stroke. Previous work suggests the 6MWT can estimate peak metabolic capacity (VO2peak) without cardiorespiratory assessments during graded exercise tests (GXTs), which may assist with exercise prescription. However, selected research also indicated increased heart rates (HRs) during 6MWTs beyond levels considered safe without GXTs.

Objective

The goal of this study was to examine cardiorespiratory responses during 6MWTs and GXTs in individuals with chronic stroke and their associations with demographic or clinical characteristics.

Design

The study used a cross-sectional observational design.

Methods

Cardiorespiratory responses were assessed during 6MWTs at self-selected velocity (SSV) and fastest velocity (FV), and during GXTs. Secondary assessments included the lower extremity Fugl-Meyer Assessment, Functional Gait Assessment, gait speeds, and daily stepping activity. Correlation and regression analyses were used to evaluate associations between locomotor performance, cardiorespiratory responses, and clinical and demographic characteristics.

Results

Average HRs during 6MWT-FV were 72% to 76% of the age-predicted maximum (HRmax), with 20% of participants exceeding 85% predicted HRmax. When normalized to HRs during GXTs, HRs during 6MWT-FV were 86% to 88% of observed HRmax. Primary predictors of increased HRs during 6MWTs were resting HR, body mass index, and daily stepping. Distance during 6MWT-FV was a significant predictor of VO2peak in combination with other variables. Electrocardiographic abnormalities were observed in >80% of participants at rest and 31% demonstrated distinct abnormalities during GXTs, which were not related to 6MWT or GXT performance.

Limitations

In addition to sample size, a primary limitation involved the ability to accurately predict or measure HRmax in patients with motor dysfunction after stroke.

Conclusions

Cardiac responses were higher than anticipated during 6MWTs and often exceeded recommended HR thresholds. Clinicians should closely monitor cardiorespiratory responses during 6MWTs.

Calf Muscle Oxygen Saturation during 6-Minute Walk Test and Its Relationship with Walking Impairment in Symptomatic Peripheral Artery Disease

BACKGROUND

Impaired microcirculation is associated with poor walking capacity in symptomatic peripheral artery disease (PAD) patients during treadmill test; however, this test does not simulate the efforts of daily walking of these patients. Thus, the aim of the study was to describe the microcirculation responses during a 6-minute walk test (6MWT) and to analyze the relationship between microcirculation indicators and walking impairment in symptomatic PAD patients.

METHODS

Thirty-four patients were included (mean age = 67.6 ± 11.2 years). Their clinical characteristics were collected, and they performed a 6MWT, in which the initial claudication distance (ICD) and total walking distance (TWD) were recorded. During and after the 6MWT, calf muscle oxygen saturation (StO₂) parameters were monitored continuously to measure microcirculation behavior. The association between calf muscle StO₂ parameters and walking impairment were analyzed by Pearson or Spearman correlations.

RESULTS

Walking impairment was not associated with any StO₂ parameters during exercise. In contrast, after 6MWT, recovery time of StO₂ (r = -0.472, P = 0.008) and recovery time to maximal StO₂ (r = -0.402, P = 0.019) were negatively correlated with ICD. Furthermore, the distance walked under claudication symptoms (ΔTWD-ICD) was positively correlated with recovery time to maximal StO₂ (r = 0.347, P = 0.048).

CONCLUSIONS

In symptomatic PAD patients, shorter ICD values during a 6MWT are associated with a delayed recovery in calf muscle StO₂ after exercise. Calf muscle StO₂ parameters decrease subtly during 6MWT, suggesting that the degree of ischemia in the calf muscle during ground walking, simulating efforts of the daily walking, is relatively low.

Six-Minute Walk Test for Assessing Physical Functional Capacity in Chronic Heart Failure

PURPOSE OF THE REVIEW

The six-minute walk test (6MWT) is a submaximal exercise test for evaluating physical functional capacity. This review aims to report the research on the use of the 6MWT in chronic heart failure (CHF) that has been published in the past 5 years.

RECENT FINDINGS

The 6MWT distance does not accurately reflect peak VO₂. Minimal clinically important difference in the 6MWT distance, and additional measurements, such as heart rate recovery, can assist in the interpretation of the 6MWT distance, so management decisions can be made. Incorporating mobile apps and information technology in measuring the 6MWT distance extends the usefulness of this simple walk test and improve remote monitoring of patients with CHF. The 6MWT is a useful tool in CHF programs. However, interpretation of the 6MWT distance must be with caution. With the advancement in technology, the 6MWT has the potential to facilitate the monitoring of people living in rural and remote areas.

Post-stroke Fatigue and Depressive Symptoms Are Differentially Related to Mobility and Cognitive Performance

Background: Fatigue and depressive symptoms are common and often inter-related stroke sequelae. This study investigates how they are related, directly or indirectly, to mobility and cognitive outcomes within 6 months of stroke.

Methods: Participants were recruited from 4 stroke centers in Ontario, Canada. Post-stroke fatigue was assessed using the Fatigue Assessment Scale (FAS). Depressive symptoms were screened using the Center for Epidemiological Studies Scale for Depression (CES-D). Factor analyses were used to construct scores from mobility (distance traveled during a 2-min walk test, Chedoke-McMaster Stroke Assessment leg score, and Berg Balance Scale total score) and cognitive (Montreal Cognitive Assessment, Trail-Making Tests A and B, and five-word free recall) tests. Direct associations were assessed in linear regression models and indirect effects were assessed in path models. Covariates were age, sex, education, antidepressant use, days since stroke, and stroke severity (National Institute of Health Stroke Severity Scale score).

Results: Fatigue and depressive symptoms were highly correlated (r > 0.51, p < 0.0001). Depressive symptoms were associated with cognition (β = −0.184, p = 0.04) and indirectly with mobility, mediated by fatigue (indirect effect = −0.0142, 95% CI: −0.0277 to −0.0033). Fatigue was associated with mobility (β = −0.253, p = 0.01), and indirectly with cognition, mediated by depressive symptoms (indirect effect = −0.0113, 95% CI: −0.0242 to −0.0023).

Conclusions: Fatigue and depressive symptoms are related distinctly to cognitive and mobility impairments post-stroke. Fatigue was associated with poorer lower limb motor function, and with cognition indirectly via depressive symptoms.

Reference Equations for the Six-Minute Walk Distance in the Healthy Chinese Han Population, Aged 18-30 Years

Background

The six-minute walk test (6MWT) is a safe, simple, inexpensive tool for evaluating the functional exercise capacity. However, there is a lack of standard reference equations for the six-minute walk distance (6MWD) in the healthy Chinese Han population with an age of 18–30 years. The aims of the present study were as follows: 1) to measure the anthropometric data and the walking distance in a sample of healthy Chinese Han population, aged 18–30 years; 2) to construct reference equations for the 6MWD; 3) to compare the measured 6MWD of our cohort with previously published equations.

Methods

The anthropometric data, demographic, lung function and the walking distance of Chinese Han population, aged 18–30 years, were prospectively measured using a standardized protocol. Informed consent was obtained from each participant and the approval was obtained from the ethics committee of Wenzhou People’s Hospital. The 6MWT was performed twice and the longer 6MWD was used for further analysis.

Results

A total of 355 subjects (176 female and 179 male) completed the 6MWT, and the average walking distance was 627.3 ± 52.88 m. The walking distance was achieved by females compared with males (607.4 ± 51.00 m vs. 646.9 ± 47.15 m; p < 0.0001) and active subjects compared with non-active subjects (646.1 ± 48.27 m vs. 611.6 ± 51.52 m; p < 0.0001). Univariate analysis showed age, height, body mass index, resting blood pressure, heart rate and blood pressure after the walk test and difference in heart rate before and after the walk test were significantly correlated with the 6MWD. Stepwise multiple regression analysis showed that height and difference in heart rate before and after the walk test were independent predictors associated with the 6MWD. The reference equations from Caucasian, Canadian and Chilean populations tend to overestimate the walking distance in our subjects, while Brazilian and Arabian equations tend to underestimate the walking distance. There was no significant difference in the walking distance between Korean equations and the current study.

Conclusion

In summary, height and difference in heart rate before and after the walk test were the most significant predictors of the 6MWD, and the regression equations could explain approximately 38% and 31% of the distance variance in the female and male groups, respectively.