Is there a learning effect when the 6-minute walk test is repeated in people with suspected pulmonary hypertension?

The Rationale, Evidence, and Adaptations to Pulmonary Rehabilitation for Chronic Respiratory Diseases Other Than COPD

Over the last 3 decades, pulmonary rehabilitation (PR) has become an integral part of the management of COPD. Many other chronic respiratory diseases have similar systemic manifestations including skeletal muscle impairment, commonly through deconditioning, and may benefit from PR. However, whereas many programs may accept patients with other respiratory diseases, the program may need several adaptations to optimally manage patients. This article uses the examples of interstitial lung disease including idiopathic pulmonary fibrosis, bronchiectasis, pulmonary hypertension, post lung transplantation, and post-COVID condition to highlight exemplar clinical problems. In addition, the rationale and latest evidence for PR are described alongside the adaptations to the program, including education needs of the delivery team and close integrated care with the wider clinical team. Finally, future directions for clinical care and research are discussed.

Delivering effective, comprehensive, multi-exercise component cardiac rehabilitation (CR) for chronic heart failure patients in low resource settings in sub-Saharan Africa: Queen Elizabeth Central Hospital-(QECH-CR) randomised CR study, Malawi

BACKGROUND

The delivery of Cardiac Rehabilitation (CR) and attaining evidence-based treatment goals are challenging in developing countries, such as Malawi. The aims of this study were to (i) assess the effects of exercise training/ CR programme on cardiorespiratory and functional capacity of patients with chronic heart failure (CHF), and (ii) examine the effectiveness of a novel, hybrid CR delivery using integrated supervised hospital- and home-based caregiver approaches.

METHODS

A pre-registered (UMIN000045380), randomised controlled trial of CR exercise therapy in patients with CHF was conducted between September 2021 and May 2022. Sixty CHF participants were randomly assigned into a parallel design-exercise therapy (ET) (n = 30) or standard of care (n = 30) groups. Resting hemodynamics, oxygen saturation, distance walked in six-minutes (6MWD) and estimated peak oxygen consumption (VO2 peak) constituted the outcome measures. The exercise group received supervised, group, circuit-based ET once weekly within the hospital setting and prescribed home-based exercise twice weekly for 12 weeks. Participants in both arms received a group-based, health behaviour change targeted education (usual care) at baseline, 8-, 12- and 16-weeks.

RESULTS

Most of the participants were female (57%) with a mean age of 51.9 ±15.7 years. Sixty-five percent (65%) were in New York Heart Association class III, mostly with preserved left ventricular ejection fraction (HFpEF) (mean Left Ventricular Ejection Fraction 52.9 ±10.6%). The 12-weeks ET led to significant reductions in resting haemodynamic measures (all P <0.05). The ET showed significantly higher improvements in the 6MWD (103.6 versus 13.9 m, p<0.001) and VO2 peak (3.0 versus 0.4 ml·kg-1·min-1, p <0.001). Significant improvements in 6MWD and VO2 peak (both p<0.001), in favour of ET, were also observed across all follow-up timepoints.

CONCLUSION

This novel, randomised, hybrid ET-based CR, delivered to mainly HFpEF patients using an integrated hospital- and home-based approach effectively improved exercise tolerance, cardiorespiratory fitness capacities and reduced perceived exertion in a resource-limited setting.

Validity and reliability of automated treadmill six-minute walk test in patients entering exercise-based cardiac rehabilitation

Introduction: The six-minute walk test (6MWT) is a well-established tool for assessing submaximal functional capacity for cardiac patients, but space limitations challenge its implementation. Treadmill-based (TR) 6MWT is a promising alternative, but it requires patients to complete a familiarization test to adapt treadmill speed regulation. With the advancement of sensors, it is possible to automatically control speed for individual patients and thus overcome the space limitation or the speed control difficulty on the treadmill for each patient.Methods: This study investigated the validity and interchangeability of automated speed TR6MWT and standard hallway (HL) 6MWT. Eighteen patients were assessed at baseline of the 12-week cardiac rehabilitation program. Fourteen of them were assessed after rehabilitation. All patients performed three TR6MWTs and three HL6MWTs at baseline and one of each test after the program.Results: Patients well tolerated the TR6MWT. There was a strong correlation between both test methods (r = 0.79). However, patients performed significantly better in HL6MWT (514.8m ± 59.7m) than in TR6MWT (447.2 ± 79.1m) with 95% CI, 40.4-94.6m, p < 0.05. Both tests showed high test-retest reliability (intraclass correlation coefficient of 0.86). The TR6MWT showed a valuable comparison of the effect of the cardiac rehabilitation program (20% increase, effect size 1.1) even though it is not interchangeable with the HL6MWT.Conclusion: The automated speed TR6MWT appears to be an acceptable tool with adequate validity, reliability, and responsiveness for assessing functional capacity in patients utilizing cardiac rehabilitation programs.

Reproducibility of the 6-minute walk test in lung transplant recipients

PURPOSE

There is reason to believe that the favorable measurement properties of the 6‑minute walk test (6MWT) reported for retest reliability and its capability to detect a true change in healthy individuals or persons with chronic respiratory disease may not apply to lung transplant recipients (LuTXr). We therefore investigated retest reliability of the 6MWT and, in addition, made an attempt to explore whether the 6MWT was sensitive enough to detect important changes that occur with postacute rehabilitation in LuTXr after first time LuTX.

METHODS

Immediately before postacute rehabilitation, 50 LuTXr completed 6MWT testing twice, separated by 1-2 workdays (retest reliability), and were reassessed after completion of rehabilitation 2 months later (sensitivity to changes). Body function measures and health-related quality of life (HRQoL) assessments were collected at baseline.

RESULTS

Baseline retest 6‑minute walk distance (6MWD) and the age-related predicted walking distance (6MWD%pred) scores significantly increased before postacute rehabilitation. The intraclass coefficient of correlation ICC of the 6MWD was 0.93 (95% confidence interval, CI: 0.88-0.96) and its smallest real difference (SRD) 79 m (95% CI: 52;107). Receiver operating curve analyses revealed the rehabilitation associated changes in 6MWD/6MWD%pred to exceed the SRD/SRD% values in a highly accurate way.

CONCLUSION

The 6MWT overall represents a reliable functional performance tool in LuTXr that is sensitive to detect changes in physical performance as a result of medical postacute rehabilitation.

Rehabilitation Program for Gait Training Using UAN.GO, a Powered Exoskeleton: A Case Report

Background: Spinal cord injury is characterized by the interruption of neural pathways of the spinal cord, with alteration of sensory, motor, and autonomic functions. Robotic-assisted gait training offers many possibilities, including the capability to reach a physiological gait pattern. Methods: A training protocol with UAN.GO^®, an active lower limb exoskeleton, was developed. A participant having D10 complete SCI was recruited for this study. The training protocol was composed by 13 sessions, lasting 1.5 h each. The effectiveness of the protocol was evaluated through the mobility performance during the 6 MWT, the level of exertion perceived administrating Borg RPE at the end of each 6 MWT. Furthermore, time and effort required by the participant to earn a higher level of skills were considered. Results: A significant improvement was registered in the six MWT (t₀ = 45.64 m t₁ = 84.87 m). Data referring to the mean level of exertion remained stable. The patient successfully achieved a higher level of independence and functional mobility with the exoskeleton. Discussion: The findings from this preliminary study suggest that UAN.GO can be a valid tool for walking rehabilitation of spinal cord injury patients, allowing the achievement of greater mobility performances.

Wearable-Based Assessment of Frailty Trajectories During Cardiac Rehabilitation After Open-Heart Surgery

Frailty in patients after open-heart surgery influences the type and intensity of a cardiac rehabilitation program. The response to tailored exercise training can be different, requiring convenient tools to assess the effectiveness of a training program routinely. The study aims to investigate whether kinematic measures extracted from the acceleration signals can provide information about frailty trajectories during rehabilitation. One hundred patients after open-heart surgery, assigned to the equal-sized intervention and control groups, participated in exercise training during inpatient rehabilitation. After rehabilitation, the intervention group continued exercise training at home, whereas the control group was asked to maintain the usual physical activity regimen. Stride time, cadence, movement vigor, gait asymmetry, Lissajous index, and postural sway were estimated during the clinical walk and stair-climbing tests before and after inpatient rehabilitation as well as after home-based exercise training. Frailty was assessed using the Edmonton frail scale. Most kinematic measures estimated during walking improved after rehabilitation along with the improvement in frailty status, i.e., stride time, cadence, postural sway, and movement vigor improved in 71%, 77%, 81%, and 83% of patients, respectively. Meanwhile, kinematic measures during stair-climbing improved to a lesser extent compared to walking. Home-based exercise training did not result in a notable change in kinematic measures which agrees well with only a negligible deterioration in frailty status. The study demonstrates the feasibility to follow frailty trajectories during inpatient rehabilitation after open-heart surgery based on kinematic measures extracted using a single wearable sensor.

Low-volume walking HIIT: Efficient strategy to improve physical capacity and reduce the risk of cardiovascular disease in older women with type 2 diabetes

BACKGROUND AND AIMS

To compare the effect of a low-volume walking high-intensity interval training (HIIT) to moderate-intensity continuous training (MICT) on risk of cardiovascular diseases and physical capacity in older women with type 2 diabetes (T2D).

METHODS

Thirty inactive older women with T2D were randomized into either HIIT (75 min/week) or MICT (150 min/week). Cardiovascular risk profile (lipid profile; waist circumference and fat mass; resting, post-exercise and ambulatory blood pressure [BP]; VO₂ peak; UKPDS score; ABC's) and physical capacity were assessed before and after a 12-week intervention.

RESULTS

While resting systolic and diastolic BP (all p ≤ 0.01) were reduced, ambulatory BP (p ≥ 0.49) and lipid profile (p ≥ 0.40) remained unchanged after the intervention. Although VO₂ peak increased to a similar extent in both groups (p = 0.015), the distance covered during the 6MWT (p = 0.01) and grip strength (p = 0.02) increased to a greater extend in HIIT. The UKPDS risk score decreased in both groups after the intervention (p = 0.03) and 31% of the participants reached the ABC's compared to 24% at baseline.

CONCLUSION

Low-volume walking HIIT is an efficient exercise intervention for older women with T2D as it improved some CVD risk factors and physical capacity. Nevertheless, neither low-volume HIIT nor MICT is sufficient to affect ambulatory blood pressure in T2D patients.

Detection of Walk Tests in Free-Living Activities Using a Wrist-Worn Device

Exercise testing to assess the response to physical rehabilitation or lifestyle interventions is administered in clinics thus at best can be repeated only few times a year. This study explores a novel approach to collecting information on functional performance through walk tests, e.g., a 6-min walk test (6MWT), unintentionally performed in free-living activities. Walk tests are detected in step data provided by a wrist-worn device. Only those events of minute-to-minute variation in walking cadence, which is equal or lower than the empirically determined maximal SD (e.g., 5-steps), are considered as walk test candidates. Out of detected walk tests within the non-overlapping sliding time interval (e.g., 1-week), the one with the largest number of steps is chosen as the most representative. This approach is studied on a cohort of 99 subjects, assigned to the groups of patients with cardiovascular disease (CVD) and healthy subjects below and over 40-years-old, who were asked to wear the device while maintaining their usual physical activity regimen. The total wear time was 8,864 subject-days after excluding the intervals of occasionally discontinued monitoring. About 82% (23/28) of patients with CVD and 88% (21/24) of healthy subjects over 40-years-old had at least a single 6MWT over the 1st month of monitoring. About 52% of patients with CVD (12/23) and 91% (19/21) of healthy subjects over 40-years-old exceeded 500 m. Patients with CVD, on average, walked 46 m shorter 6MWT distance (p = 0.04) compared to healthy subjects. Unintentional walk testing is feasible and could be valuable for repeated assessment of functional performance outside the clinical setting.

Test-retest reliability of stability outcome measures during treadmill walking in patients with balance problems and healthy controls

BACKGROUND

Improvement of balance control is an important rehabilitation goal for patients with motor and sensory impairments. To quantify balance control during walking, various stability outcome measures have described differences between healthy controls and patient groups with balance problems. To be useful for the evaluation of interventions or monitoring of individual patients, stability outcome measures need to be reliable.

RESEARCH QUESTION

What is the test-retest reliability of six stability outcome measures during gait?

METHODS

Patients with balance problems (n = 45) and healthy controls (n = 20) performed two times a two-minute walk test (2MWT). The intraclass correlation coefficient (ICC) and Bland-Altman analysis (coefficient of repeatability; CR) were used to evaluate the test-retest reliability of six stability outcome measures: dynamic stability margin (DSM), margin of stability (MoS), distance between the extrapolated centre of mass (XCoM) and centre of pressure (CoP) in anterior-posterior (XCoM-CoP_AP) and medial-lateral (XCoM-CoP_ML) direction, and inclination angle between centre of mass (CoM) and CoP in anterior-posterior (CoM-CoP_AP-angle) and medial-lateral (CoM-CoP_ML-angle) direction. A two way mixed ANOVA was performed to reveal measurement- and group-effects.

RESULTS

The ICCs of all stability outcome measures ranged between 0.51 and 0.97. Significant differences between the measurements were found for the DSM (p = 0.017), XCoM-CoP_AP (p = 0.008) and CoM-CoP_AP-angle (p = 0.001). Significant differences between controls and patients were found for all stability outcome measures (p < 0.01) except for the MoS (p = 0.32). For the XCoM-CoP distances and CoM-CoP angles, the CRs were smaller than the difference between patients and controls.

SIGNIFICANCE

Based on the ICCs, the reliability of all stability outcome measures was moderate to excellent. Since the XCoM-CoP_ML and CoM-CoP_ML-angle showed no differences between the measurements and smaller CRs than the differences between patients and controls, the XCoM-CoP_ML and CoM-CoP_ML-angle seem the most promising stability outcome measures to evaluate interventions and monitor individual patients.

Six-Minute Walk Test: Clinical Role, Technique, Coding, and Reimbursement

The 6-min walk test (6MWT) is a commonly used test for the objective assessment of functional exercise capacity for the management of patients with moderate-to-severe pulmonary disease. Unlike pulmonary function testing, the 6MWT captures the often coexisting extrapulmonary manifestations of chronic respiratory disease, including cardiovascular disease, frailty, sarcopenia, and cancer. In contrast with cardiopulmonary exercise stress testing, this test does not require complex equipment or technical expertise. In this low complexity, safe test, the patient is asked to walk as far as possible along a 30-m minimally trafficked corridor for a period of 6 min with the primary outcome measure being the 6-min walk distance (6MWD) measured in meters. There has been interest in other derived indexes, such as distance-desaturation product (the product of nadir oxygen saturation and walk distance), which in small studies has been predictive of morbidity and mortality in certain chronic respiratory conditions. Special attention to methodology is required to produce reliable and reproducible results. Factors that can affect walk distance include track layout (continuous vs straight), track length, oxygen amount and portability, learning effect, and verbal encouragement. The absolute 6MWD and change in 6MWD are predictive of morbidity and mortality in patients with COPD, pulmonary arterial hypertension, and idiopathic pulmonary fibrosis and patients awaiting lung transplant, highlighting its use in management decisions and clinical trials. As of January 2018, Current Procedural Terminology code 94620 (simple pulmonary stress test) has been deleted and replaced by two new codes, 94617 and 94618. Code 94617 includes exercise test for bronchospasm including pre- and postspirometry, ECG recordings, and pulse oximetry. Code 94618, pulmonary stress testing (eg, 6MWT), includes the measurement of heart rate, oximetry, and oxygen titration when performed. If 94620 is billed after January 2018 it will not be reimbursed.

Effect of a mixed-exercise program on physical capacity and sedentary behavior in older adults during cancer treatments

BACKGROUND

Aging, cancer and its treatment all contribute to increase the risk of deconditioning and sedentary behaviors. Mixed exercise is recognized to counteract the effects of aging and deconditioning as well as improving physical capacity during cancer treatment in adults.

AIMS

To determine the impact of a mixed exercise program (MXEP) to improve physical capacity and decrease sedentary behavior time (SBT) in older adults during cancer treatment.

METHODS

Fourteen participants (68.8 ± 3.4 years) completed 12 weeks of a mixed exercise program (MEXP) (n = 6) or stretching (n = 8) while they were under cancer treatment. Five tests of the Senior Fitness Test (Chair Stand, 8-Foot Up & Go, Arm Curl, Sit & Reach, 6 min Walk Test), two maximal strength tests (leg press and handgrip) and a Global Physical Capacity Score (GPCS) were used to assess physical capacity. For the amount of SBT (min/day), we used question 1 of the Physical Activity Scale for the Elderly.

RESULTS

Both groups presented significant pre- vs post-intervention differences for the Chair Stand, Arm Curl, 6 min Walk Tests and also GPCS. Nevertheless, this difference was significantly greater in the MEXP group only for the Chair Stand Test (4.3 ± 2.2 vs 1.0 ± 1.3 reps; p = 0.01) and the GPCS (4.0 ± 0.6 vs 1.5 ± 2.3 points; p = 0.047). A tend to display a greater decrease in SBT (- 295 ± 241 min/week vs - 11 ± 290 min/week; p = 0.079) was observed in favor of MEXP.

CONCLUSION

A 12-week mixed exercise program led to significant improvements in physical capacity and may reduce SBT.

6-minute walking test: a useful tool in the management of heart failure patients

Reduced functional ability and exercise tolerance in patients with heart failure (HF) are associated with poor quality of life and a worse prognosis. The 6-minute walking test (6MWT) is a widely available and well-tolerated test for the assessment of the functional capacity of patients with HF. Although the cardiopulmonary exercise test (a maximal exercise test) remains the gold standard for the evaluation of exercise capacity in patients with HF, the 6MWT (submaximal exercise test) may provide reliable information about the patient’s daily activity. The current review summarizes the value of 6MWT in patients with HF and identifies its usefulness and limitations in everyday clinical practice in populations of HF. We aimed to investigate potential associations of 6MWD with other measures of functional status and determinants of 6MWD in patients with HF as well as to review its prognostic role and changes to various interventions in these patients.

A performance comparison of the 20 and 30 meter six-minute walk tests among middle aged and older adults

Objective: To compare the performance of the Six-Minute Walk Test on 20-meter (6MWT₂₀) and 30-meter (6MWT₃₀) tracks and to test the validity and reliability of the 6MWT₂₀ in middle-aged and older adults.Method: The subjects underwent lung function assessment and performed the 6MWT₃₀ and 6MWT₂₀. Student´s t-tests or Wilcoxon tests were used to compare the variables. The Pearson or Spearman correlation coefficients were used to evaluate the validity of the 6MWT₂₀ and the reliability of the 6MWT₂₀. The 6MWT₃₀ was tested by the two-way mixed model of the Intraclass Correlation Coefficient (ICC 3,1).Results: Twenty-five subjects (age: 60 ± 10 years) walked, on average, 11.0 ± 21.9 m more in the 6MWT₃₀ than in the 6MWT₂₀ (p < .05). The walking distance, the number of steps, the energy expenditure and the movement intensity between the 6MWT₂₀ and 6MWT₃₀ was correlated (r = 0.95; r = 0.81; r = 0.91; r = 0.67; respectively, p < .001). The walking distances showed high reliability and were similar between test and re-test in the 6MWT₃₀ (544 ± 72.1 vs. 551 ± 70.5; p < .05; ICC = 0.97) and in the 6MWT₂₀ (533 ± 73.1 vs. 532 ± 59.1; p < .05; ICC = 0.87).Conclusion: The 6MWT₂₀ performance is lower than the 6MWT₃₀ However, this difference is not clinically relevant. Additionally, the 6MWT₂₀ is a valid and reproducible test to assess the functional capacity of middle-aged and older adults.

Practice effect and cueing of 2-minute walk test, 6-minute walk test and 10-meter walk test in frail older adults with and without dementia - Recommendations to walk tests protocols

OBJECTIVES

1) To determine if there was a practice effect associated with walk tests performed by frail older adults with and without dementia, 2) to examine the role of systematic cueing in the walk tests for those with dementia, and 3) to make recommendations to testing protocols of the walk tests for frail older adults with and without dementia.

SETTING

Residential and day care facilities.

PARTICIPANTS

44 frail older adults with normal cognition (NON-DEM) and 39 older adults with Alzheimer's disease or dementia (DEM) who were able to walk independently for at least 15 m.

METHODS

All the participants completed multiple trials of 2-minute walk test (2MWT), 6-minute walk test (6MWT) and 10-meter walk test (10MeWT) on three separate testing occasions. The DEM group was facilitated to complete the walk tests using a progressive cueing system.

RESULTS

Significant increases in the walking performance within the same testing occasion were found in the 2MWT (NON-DEM: p = .002; DEM: p ≤ .044) and 6MWT (NON-DEM: p ≤ .004; DEM: p ≤ .002) for both groups but only in the 10MeWT (p ≤ .023) for the DEM group. Significant increases in the walking performance across testing occasions were shown in the 2MWT (p ≤ .047), 6MWT (p ≤ .005) and 10MeWT (p ≤ .039) for the NON-DEM group but not the DEM group (all p > .05). Multivariate regression analyses showed that the cognitive function of the DEM group was independently and inversely associated with the level of cueing provided during the walk tests (p ≤ .007).

CONCLUSION

Practice effect associated with the walk tests was found within and across testing occasions for frail older adults with normal cognition, and only within the same testing occasion for those with dementia. Systematic cueing should be provided for those with dementia to complete the walk tests. Testing protocols of the walk tests have been recommended for these two population groups.

Intra- and inter-rater reproducibility of the 6-minute walk test and the 30-second sit-to-stand test in patients with severe and very severe COPD

Background

In patients with COPD, the 6-minute walk test (6MWT) and the 30-second sit-to-stand test (30sec-STS) are widely used as clinical outcome measures of walking capacity, lower limb muscle strength, and functional ability. Due to a documented learning effect, at least two trials are recommended for assessment. The aim of our study was to investigate the intra- and inter-rater reliability and agreement of the two tests in patients with severe and very severe COPD (FEV₁ <50%).

Patients and methods

Fifty patients (22 females; mean [SD]: age 67 [9] years, FEV₁ predicted 32 [9]%) were assessed with the 6MWT and the 30sec-STS twice by the same assessor on test-day 1 (T1) and by another assessor 7–10 days later on test-day 2 (T2).

Results

The 6MWT intra- and inter-rater reliability (intraclass correlation coefficient, ICC_1.1) was 0.98 (lower limit 95% CI: 0.94) and 0.96 (lower limit 95% CI: 0.94), respectively, and agreement (standard error of the measurement, SEM) was 14.8 and 20.5 m, respectively. The 30sec-STS intra- and inter-rater reliability and agreement results were, respectively, ICC_1.1 0.94 (lower limit 95% CI: 0.90) and 0.92 (lower limit 95% CI: 0.86), with SEM of 0.97 and 1.14 repetitions. There was no difference (95% CI: −5.3; 8.1) between the 6MWT distances on T1, while the mean walking distance improved 7.9 m (0.0 m; 15.8 m) from T1 to T2. Improvement on the same test date was less likely (OR: 3.6 [95% CI: 1.1; 11.8], Fisher’s exact test, P=0.047) in patients who walked less than 350 m in the 6MWT. We found no clinically relevant learning effect in the 30sec-STS.

Conclusion

In patients with severe and very severe COPD the 6MWT and the 30sec-STS showed excellent intra- and inter-rater reliability and acceptable agreement. No learning effect was documented for the tests when performed on the same day. Our data suggest that in clinical practice using different assessors is acceptable, and that a single test trial may be sufficient to assess patients with severe and very severe COPD.