Physiologic Responses to Incremental and Self-Paced Exercise in COPD

Perioperative Exercise Testing in Pregnant and Non-Pregnant Women of Reproductive Age: A Systematic Review

BACKGROUND

Women have classically been excluded from the development of normal data and reference ranges, with pregnant women experiencing further neglect. The incidence of Caesarean section in pregnant women, and of general operative management in young women (both pregnant and non-pregnant), necessitates the formal development of healthy baseline data in these cohorts to optimise their perioperative management. This systematic review assesses the representation of young women in existing reference ranges for several functional exercise tests in common use to facilitate functional assessment in this cohort.

METHODS

Existing reference range data for the exercise tests the Six Minute Walk Test (6MWT), the Incremental Shuttle Walk Test (ISWT) and Cardiopulmonary Exercise Testing (CPET) in young women of reproductive age were assessed using the MEDLINE (Ovid) database, last searched December 2023. Results were comparatively tabulated but not statistically analysed given underlying variances in data.

RESULTS

The role of exercise testing in the perioperative period as an assessment tool, as well as its safety during pregnancy, was evaluated using 65 studies which met inclusion criteria.

CONCLUSION

There is a significant lack of baseline data regarding these tests in this population, especially amongst the pregnant cohort, which limits the application of exercise testing clinically.

Normative reference values, determinants and regression equations for the incremental shuttle walk test (ISWT) in healthy Asian population aged 21 to 80 years

BACKGROUND

The validated Incremental Shuttle Walk Test (ISWT) is widely used for evaluating maximal exercise capacity, with the distance-walked (IWSD) as the primary outcome. However, there are no normative reference values (NRV) and reference equations to predict ISWD for the Singaporean population.

OBJECTIVES

This study aims to establish the NRV and reference equations for ISWD in healthy Singaporeans aged 21 to 80 and investigate the determining variables during ISWT.

METHODS

This cross-sectional study recruited community-dwelling healthy subjects aged 21-80 from the community via convenience sampling. Each subject completed two trials of the ISWT according to the standard protocol. Variables measured during the trials included ISWD, pre-and post-test heart rate (HR), oxygen saturation, blood pressure (BP), modified Borg's dyspnoea score and Borg's rate of perceived exertion (RPE).

RESULTS

199 healthy Singaporean (females = 114, males = 85) participated in the study. The overall median ISWD was 660.0 metres (m) [interquartile range (IQR):440.0-850.0]. The age-stratified mean ISWD ranged from 430.0 m (IQR:350.0-450.0) (aged 60-80) to 480.0 m (IQR:438.0-650.0) (aged 40-59) to 780.0 m (IQR:670.0-960.0) (aged 21-39). Gender, age, weight, height and HR change (highest post-test HR minus pre-test HR) were the most significant variables (p < 0.001). IWSD (m) = 651.4(Height, m) +89.7(Gender, male = 1; female = 0) -6.31(Age, years) -3.61(Weight, kilograms) +2.54(HR change, beats per minute); R2 = 0.741. Previously published ISWT reference equations cannot accurately predict the ISWD in the Singaporean population.

CONCLUSIONS

This study investigated the ISWD NRV and established reference equations for healthy Singaporeans aged 21-80. The information would be beneficial in setting performance benchmarks to guide physical assessment, intervention and rehabilitation.

Poor cardiorespiratory fitness may be an indicator of more severe liver inflammation in non-alcoholic fatty liver disease patients

INTRODUCTION

Non-alcoholic fatty liver disease (NAFLD) is related to cardiovascular disease. Cardiorespiratory fitness (CRF) is an important indicator of cardiovascular health. Therefore, we aimed to evaluate the CRF of NAFLD patients.

METHODS

Cross-sectional study, including 32 patients with biopsy-proved NAFLD. The patients underwent ergometric test (ET) and six-minute walk test (6MWT) to determine CRF. The test results were compared to disease parameters and with each other.

RESULTS

Considering the ET, 20 (62.5%) patients had very poor or poor CRF, and in 12 (37.5%), it was regular or good. In the 6MWT, 13 (40.6%) individuals had poor CRF, in 12 (37.5%), it was very poor, and in seven (21.9%), regular. NAFLD activity score (NAS) ≥5 was observed in 12 (37.5%) individuals. Twelve (37.5%) patients were sedentary, 11 (34.4%), insufficiently active, and nine (28.1%), active. Obesity and liver inflammation on biopsy were associated with very poor/poor CRF. NAS ≥5 and sedentary lifestyle were independently associated with very poor/poor CRF by ET. Although mean VO2max values determined by both tests were similar, no correlation of VO2max determined by ET and 6MWT was observed, as occurred for the distance walked in 6MWT and values of metabolic equivalent (MET) determined by ET. There was no reproducibility between CRF determined by ET and 6MWT.

CONCLUSION

Most NAFLD patients had very poor or poor CRF. Severe liver injury (NAS ≥5) and sedentary lifestyle were independently associated with very poor/poor fitness, according to ET. No reproducibility was observed between the CRF defined by ET and 6MWT.

In adults with advanced lung disease, the 1-minute sit-to-stand test underestimates exertional desaturation compared with the 6-minute walk test: an observational study

QUESTION

In adults with advanced lung disease, do the 6-minute walk test (6MWT) and 1-minute sit-to-stand test (1minSTS) elicit similar cardiorespiratory responses? Can the 6-minute walk distance (6MWD) be estimated from the 1minSTS result?

DESIGN

Prospective observational study using data collected during routine clinical practice.

PARTICIPANTS

Eighty adults (43 males) with advanced lung disease, a mean age of 64 years (SD 10) and a mean forced expiratory volume in 1 second of 1.65 L (SD 0.77).

OUTCOME MEASURES

Participants completed a 6MWT and a 1minSTS. During both tests, oxygen saturation (SpO2), pulse rate, dyspnoea and leg fatigue (Borg 0 to 10) were recorded.

RESULTS

Compared with the 6MWT, the 1minSTS resulted in higher nadir SpO2 (MD 4%, 95% CI 3 to 5), lower end-test pulse rate (MD -4 beats/minute, 95% CI -6 to -1), similar dyspnoea (MD -0.3, 95% CI -0.6 to 0.1) and greater leg fatigue (MD 1.1, 95% CI 0.6 to 1.6). Among the participants who demonstrated severe desaturation (SpO2 nadir < 85%) on the 6MWT (n = 18), five and ten participants were classified as moderate (nadir 85 to 89%) or mild desaturators (nadir ≥ 90%), respectively, on the 1minSTS. The relationship between the 6MWD and 1minSTS was: 6MWD (m) = 247 + (7 × number of transitions achieved during the 1minSTS) with poor predictive ability (r2 = 0.44).

CONCLUSION

The 1minSTS elicited less desaturation than the 6MWT and classified a smaller proportion of people as 'severe desaturators' on exertion. It is therefore inappropriate to use the nadir SpO2 recorded during a 1minSTS to make decisions about whether strategies are needed to prevent severe transient exertional desaturation during walking-based exercise. Further, the extent to which performance on the 1minSTS can estimate a person's 6MWD is poor. For these reasons, the 1minSTS is unlikely to be helpful when prescribing walking-based exercise.

Assessment of Exercise Capacity in Post-COVID-19 Patients: How Is the Appropriate Test Chosen?

There is a wide range of sequelae affecting COVID-19 survivors, including impaired physical capacity. These sequelae can affect the quality of life and return to work of the active population. Therefore, one of the pillars of following-up is the evaluation of physical capacity, which can be assessed with field tests (such as the six-minute walk test, the one-minute standing test, the Chester step test, and the shuttle walking test) or laboratory tests (such as the cardiopulmonary exercise test). These tests can be performed in different contexts and have amply demonstrated their usefulness in the assessment of physical capacity both in post-COVID-19 patients and in other chronic respiratory, metabolic, cardiologic, or neurologic diseases. However, when traditional tests cannot be performed, physical function can be a good substitute, especially for assessing the effects of an intervention. For example, the Short Physical Performance Battery assessment and the Timed Up and Go assessment are widely accepted in older adults. Thus, the test should be chosen according to the characteristics of each subject.

Exercise oxygen desaturation is a predictor of cardiopulmonary complications after lung resection

BACKGROUND

To investigate whether oxygen desaturation during low technology tests was associated with complications after lung resection.

METHODS

A retrospective cohort study was conducted on 1097 candidates for pulmonary resection; seven metabolic equivalents in the Master's double two-step test were loaded. The predicted postoperative (PPO) forced expiratory volume in 1 s and PPO diffusing capacity of the lung for carbon monoxide were estimated. The patients were divided into three groups: those with both values ≥60% (≥60% group (n=298)), either value <30% (<30% group (n=112)) and others (30%-60% group (n=687)). The relationships between postoperative cardiopulmonary complications and exercise stress test based on availability, symptoms and percutaneous oxygen saturation values were investigated in each group.

RESULTS

Τhe cardiopulmonary morbidity rates in the ≥60%, 30%-60%, and <30% groups were 7.7%, 14.6%, and 47.3%, respectively. Multivariate analyses revealed that predictors of complications were age (OR 0.96; p<0.001), male sex (OR 1.74; p=0.016) and exercise oxygen desaturation (EOD) >4% (OR 2.39; p=0.001) in the 30%-60% group, and male sex (OR 3.76; p=0.042) and EOD >4% (OR 2.28; p=0.030) in the <30% group.The two-flight test (TFT) was performed in 181 patients (22.8%); desaturation >4% in the TFT was also a predictor of complications.

CONCLUSIONS

A low technology test is also valuable for high-risk patients. EOD >4% is a predictor of postoperative complications.

CLINICAL REGISTRATION

This study is a non-interventional observational study and has not been registered in a public database. The study followed the Strengthening the Reporting of Observational Studies in Epidemiology reporting guidelines.This study was approved by the Ethics Committee of the Juntendo University School of Medicine (no. 2016085).

Chinese (Mandarin) translation of the incremental shuttle walk test and its validity and reliability: A cross-sectional study

BACKGROUND/PURPOSE

To date, there are no published validated Chinese versions of the incremental shuttle walk test (ISWT) instructions despite its wide clinical applications. Translation of the Chinese ISWT instruction is done in an ad-hoc manner within the Chinese-speaking populations, affecting the test's reliability and validity since translation can differ significantly between individuals. This warrants the need for psychometric testing of such translation.

OBJECTIVES

To develop a Chinese (Mandarin) version of the ISWT instructions (ISWT-CHN) that is conceptually equivalent to the original English version (ISWT-ENG) and establish its reliability and validity.

METHODS

Forward and backward translations from the ISWT-ENG were done to generate the ISWT-CHN. Face and content validity was determined during the translation process. Intra-rater and inter-rater reliability of the ISWT-CHN, construct and criterion validity were established by analysing the ISWT and the gold standard cardiopulmonary exercise test results.

RESULTS

The Item-Content validity index (I-CVI), Scale-level-Content validity index (S-CVI), and content validity ratio (CVR) of the ISWT-CHN were 1.0. Intra-class Correlation Coefficient (ICC) for inter-rater reliability between two raters were excellent (ICC = 0 . 99 , 95% CI 0.97-1.0, p < 0 . 001 ; SEM = 0 . 85 m, MDC = 2 . 35 m). The intra-rater reliability of both Raters A (ICC = 0 . 92 , 95% CI 0.53-0.98, p = 0 . 003 ; SEM = 35 m, MDC = 97 m) and B (ICC = 0 . 90 , 95% CI 0.76-0.96, p < 0 . 001 ; SEM = 32 m, MDC = 88 m) were good. In a sample of 32 healthy participants, both ISWT-CHN and ISWT-ENG instruction results showed low-positive correlations with the VO2 max determined from the cardiopulmonary exercise test (r = 0.439, p < 0 . 001 ; r = 0 . 448 , p < 0 . 001 ). There is a very high correlation between ISWT-ENG and ISWT-CHN results with no statistically significant differences (r = 0 . 967 , p < 0 . 001 ). The construct and criterion validity of the ISWT-CHN were established.

CONCLUSION

This study developed the ISWT-CHN and showed that it is a valid and reliable measure conceptually comparable to the ISWT-ENG. It will benefit the determination of functional exercise capacity in Chinese-speaking populations.

KEY MESSAGES

•This study is aimed to develop a Chinese (Mandarin) version of the ISWT instructions.•The ISWT Chinese translation is valid and reliable that is conceptually comparable to the original English instruction.•The translated ISWT-Chinese instruction will enable the use of ISWT among the Chinese-speaking populations.

Evaluation of maximal exercise capacity through the incremental shuttle walking test in lymphangioleiomyomatosis

BACKGROUND

The cardiopulmonary exercise test (CPET) is the gold standard for assessing aerobic fitness; however, it is expensive, not widely available, and requires specialized equipment and staff. The incremental shuttle walking test (ISWT) is an exercise field test used to evaluate exercise capacity and may be an alternative to CPET in patients with lymphangioleiomyomatosis (LAM).

OBJECTIVE

To investigate whether the ISWT can be used to assess maximal aerobic capacity in patients with LAM.

METHODS

Forty-five women were evaluated on two days, and they randomly performed the CPET and ISWT. The maximum oxygen uptake (peak VO2) was evaluated using gas analyzers in both tests. The carbon dioxide production (VCO2), respiratory exchange ratio (RER), and heart rate (HR) were compared during peak exercise. Pearson's correlation and Bland-Altman assessed the association and agreement, respectively. The intraclass correlation coefficient (ICC) was used to assess the reliability of the data.

RESULTS

All patients (46.1 ± 10.2 years) presented similar peak VO2, RER, and peak HR during the CPET and ISWT (15.6 ± 4.6 vs. 15.7 ± 4.4 ml·kg-1·min-1; 1.15±0.09 vs. 1.17±0.12; and 142.2 ± 18.6 vs. 141.5 ± 22.2 bpm, respectively; p>0.05). A good linear correlation (r = 0.79; p<0.001) and ICC (0.86; 95%CI 0.74-0.93) were observed between the peak VO2 in both tests. Predictive peak VO2 equations based on the ISWT performance are also presented.

CONCLUSION

Our results suggest that the ISWT can be used to assess maximal exercise performance in patients with LAM, and it is a valuable option to be used as an alternative to the CPET and predict maximal exercise capacity.

Correlation Comparison and Personalized Utility of Field Walking Tests in Assessing the Exercise Capacity of Patients with Chronic Obstructive Pulmonary Disease: A Randomized Controlled Trial

Background: Incremental shuttle walking tests (ISWT) are regarded as valuable alternatives to 6-min walking tests (6MWT) and cardiopulmonary exercise tests (CPET) owing to the maximal and externally paced loading. This study investigated the validity and reliability of ISWT by analyzing the correlation of the distances of two field tests with peak oxygen consumption (VO2) of CPET in patients with COPD. Methods: In this randomized controlled trial, patients with COPD were enrolled from two hospitals. Three assessments were performed for all patients. The ISWT and 6MWT were repeated twice in Hospital 1 to assess reliability. Results: A total of 29 patients were enrolled. The distances of ISWT (0.782, p < 0.001) and 6MWT (0.512, p = 0.005) correlated with peak VO2. The intraclass correlation coefficients of both ISWT (0.988, p < 0.001) and 6MWT (0.959, p < 0.001) was high. Patients with higher peak VO2 walked a longer distance in ISWT than 6MWT (r = 0.590, p < 0.001). Conclusions: The ISWT more highly correlates with peak VO2 than the 6MWT and has excellent reliability in patients with COPD. According to peak VO2, the walking distances of each field test varied, suggesting that the application should be personalized for the exercise capacity.

Stronger correlation of peak oxygen uptake with distance of incremental shuttle walk test than 6-min walk test in patients with COPD: a systematic review and meta-analysis

Background

The 6-min walk test (6MWT) and incremental shuttle walk test (ISWT) are valid and reliable measures to assess exercise capacity of patients with chronic obstructive pulmonary disease (COPD). However, the comparison of correlation between peak oxygen uptake (peak VO₂) and 6MWT or ISWT distance has not been investigated. We aimed to investigate the correlation between peak VO₂ and 6MWT and ISWT distances in COPD patients through a meta-analysis.

Methods

We systematically searched MEDLINE, Scopus, Embase, and the Cochrane Library up to June, 2020 for studies comparing the correlation of peak VO₂ with either 6MWT or ISWT in COPD patients. Meta-analysis was performed with R software using a fixed-effect model. We compared the correlation coefficient and measured the heterogeneity using I² statistics.

Results

We identified 12 studies involving 746 patients. Meta-analysis showed a significant correlation between peak VO₂ and 6MWT and ISWT distances (6MWT: r = 0.65, 95% CI 0.61–0.70; ISWT: r = 0.81, 95% CI 0.74–0.85; p < 0.0001). The heterogeneity was lower in ISWT than in 6MWT (6MWT: I² = 56%, p = 0.02; ISWT: I² = 0%, p = 0.71). Subgroup analysis showed a higher correlation coefficient in the low exercise capacity group than in the high exercise capacity group in both field tests.

Conclusions

6MWT and ISWT significantly correlated with peak VO₂. Our findings suggest that ISWT has a stronger correlation with peak VO₂ than 6MWT. The exercise capacity in COPD patients may affect the strength of the relationship between peak VO₂ and walking distance in both field tests, suggesting the importance of using various exercise tests.

Trial registration CRD 42020200139 at crd.york.ac.uk/prospero/

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-01897-0.

Cross-Validation of Predictive Equation for Cardiorespiratory Fitness by Modified Shuttle Walk Test in Adults with Schizophrenia: A Secondary Analysis of the CORTEX-SP Study

Cardiorespiratory fitness (CRF) can be direct or estimated from different field tests. The Modified Shuttle Walk Test (MSWT) is suitable for all levels of function, allowing a peak response to be elicited. Therefore, we aimed (1) to validate the equation presented in the original study by Singh et al. for evaluating the relationship between MSWT with peak oxygen uptake (VO_2peak) in adults with schizophrenia (SZ), (2) to develop a new equation for the MSWT to predict VO_2peak, and (3) to validate the new equation. Participants (N = 144, 41.3 ± 10.2 years old) with SZ performed a direct measurement of VO_2peak through a cardiopulmonary exercise test and the MSWT. A new equation incorporating resting heart rate, body mass index, and distance from MSWT (R² = 0.617; adjusted R² = 0.60; p < 0.001) performs better than the Singh et al. equation (R² = 0.57; adjusted R² = 0.57; p < 0.001) to estimate VO_2peak for the studied population. The posteriori cross-validation method confirmed the model’s stability (R² = 0.617 vs. 0.626). The findings of the current study support the validity of the new regression equation incorporating resting heart rate, body mass index, and distance from MSWT to predict VO_2peak for assessment of CRF in people with SZ.

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.

Rehabilitation effects of land and water-based aerobic exercise on lung function, dyspnea, and exercise capacity in patients with chronic obstructive pulmonary disease: A systematic review and meta-analysis

BACKGROUND

We sought to synthesize the evidence about aerobic exercise intervention during pulmonary rehabilitation, and to further explore the difference in rehabilitation effects between water and land-based aerobic exercise. This review's purpose is to provide a basis by which practitioners and therapists can select and create appropriate therapeutic programs.

METHODS

Data of randomized and quasi-randomized controlled trials comparing training group (TG, aerobic exercise in water or land) and control group (CG, usual care) in chronic obstructive pulmonary disease (COPD) patients (January 1, 2000-December 28, 2019) were obtained from the Cochrane Library, PubMed, Embase, China National Knowledge Infrastructure, and Wanfang databases. Two researchers independently reviewed the literature, extracted the data, and evaluated the quality of the literature. Review Manager software (Rev Man 5.3; Cochrane, London, UK) was used for meta-analysis. The rehabilitation effect of water- or land based aerobic exercise was evaluated by subgroup analysis. The proposed systematic review details were registered in PROSPERO (CRD 42020168331).

RESULTS

Eighteen studies (1311 cases of COPD) were included. Meta-analysis results show that compared with the control group, the dyspnea level and functional and endurance exercise capacity in COPD patients were significantly improved after aerobic exercise (P < .05), but there was no significant change in lung function (P > .05). Compared with land-based aerobic exercise, water-based aerobic exercise significantly improved the endurance exercise capacity in COPD patients (mean difference [MD]: 270.18, 95% CI: 74.61-465.75).

CONCLUSION

Medium to high-quality evidence shows that aerobic exercise can effectively improve dyspnea and exercise capacity in COPD patients. Compared with land-based aerobic exercise, water-based aerobic exercise had a significant additional effect in improving the endurance exercise capacity of COPD patients.

Exercise-induced desaturation in subjects with non-cystic fibrosis bronchiectasis: laboratory-based tests versus field-based exercise tests

Objective:

To investigate the validity of field walking tests to identify exercise-induced hypoxemia and to compare cardiorespiratory responses and perceived effort between laboratory-based and field-based exercise tests in subjects with bronchiectasis.

Methods:

This was a cross-sectional study involving 72 non-oxygen-dependent participants (28 men; mean age = 48.3 ± 14.5 years; and mean FEV₁ = 54.1 ± 23.4% of the predicted value). The participants underwent cardiopulmonary exercise testing (CPET) on a treadmill and constant work-rate exercise testing (CWRET) on the same day (1 h apart). In another visit, they underwent incremental shuttle walk testing (ISWT) and endurance shuttle walk testing (ESWT; 1 h apart). Desaturation was defined as a reduction in SpO₂ ≥ 4% from rest to peak exercise.

Results:

CPET results were compared with ISWT results, as were CWRET results with ESWT results. There was no difference in the magnitude of desaturation between CPET and ISWT (−7.7 ± 6.3% vs. −6.6 ± 5.6%; p = 0.10) and between CWRET and ESWT (−6.8 ± 5.8% vs. −7.2 ± 6.3%; p = 0.50). The incremental tests showed an agreement in the magnitude of desaturation in the desaturation and no desaturation groups (42 and 14 participants, respectively; p < 0.01), as did the endurance tests (39 and 16 participants; p < 0.01). The magnitude of desaturation was similar among the participants who did or did not reach at least 85% of the maximum predicted HR.

Conclusions:

Field exercise tests showed good precision to detect desaturation. Field tests might be an alternative to laboratory tests when the clinical question is to investigate exercise-induced desaturation in subjects with bronchiectasis.

Ventilatory constraint is more severe in walking than cycling in patients with COPD

Due to its effectivity in assessing functional capacity and adding prognostic information to the staging of chronic obstructive pulmonary disease (COPD) patients, the 6-min walk test (6MWT) is extensively used in clinical evaluation. Currently, there is little information about the physiological response this test elicits in patients, especially when compared to cardiopulmonary exercise test (CPET). The aim of the study was to compare ventilatory and metabolic responses between these tests commonly used for the assessment of clinical outcome. A group of 20 patients with moderate to very severe COPD were tested for their pulmonary function (flow-volume curve, static lung volumes), occlusion mouth pressures and breath-by-breath measurement of flow, volumes, and oxygen (O₂) and carbon dioxide (CO₂) concentration during the 6MWT and CPET. All parameters measured during both exercise tests were assessed over the throughout of the tests and compared between each other at specified time points. Serially measured inspiratory vital capacity (IVC) decreased more rapidly and extensively during the walk-test (p ​< ​0,0001). This was accompanied by a limited increase in tidal volume (V_T) and minute ventilation (V_E), which were significantly lower in the course of the 6MWT (p ​= ​0,0003 and p ​= ​0,0097, respectively). We also noticed a significant decrease in hemoglobin oxygen saturation (SpO₂) during the 6MWT which was correlated to percent decrease in IVC (p ​= ​0,0206). Over the course of the 6MWT, oxygen consumption (VO₂) and V_T reached plateau within 2 ​min, while carbon dioxide production (VCO₂) and V_E within 3 ​min. During CPET, VO₂, VCO₂ and V_E rose continuously, while V_T reached plateau within 4 ​min. The 6MWT seems to be a rather endurance-based test associated with more pronounced dynamic lung hyperinflation and mechanical constraint of ventilation in comparison to cycling.

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Various types of exercise are tolerated differently.

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The 6MWT is, as opposed to ergometry, accompanied by a quicker increase in dynamic lung hyperinflation and desaturation.

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It seems that pedaling, as compared to walking, is the superior way of training movement for rehabilitation purposes.

A Comparison of Cardiopulmonary Exercise Testing and Field Walking Tests in Community-Dwelling Older Adults With Mild-to-Moderate Alzheimer's Dementia

The purpose of this study was to investigate the relationships among peak exercise parameters on 6-min walk test, shuttle walk test, and laboratory-based cardiopulmonary exercise testing in persons with Alzheimer's dementia. This study is a cross-sectional analysis of the baseline data of 90 participants (age 77.1 [6.6] years, 43% female) from the FIT-AD trial. Cardiopulmonary exercise testing produced significantly higher peak heart rate (118.6 [17.5] vs. 106 [22.8] vs. 106 [18.8] beats/min), rating of perceived exertion (16 [2.1] vs. 12 [2.3] vs. 11 [2.1]), and systolic blood pressure (182 [23.7] vs. 156 [18.9] vs. 150 [16.9] mmHg) compared with the shuttle walk test and 6-min walk test, respectively. Peak walking distance on shuttle walk test (241.3 [127.3] m) and 6-min walk test (365.0 [107.9] m) significantly correlated with peak oxygen consumption (17.1 [4.3] ml·kg-1·min-1) on cardiopulmonary exercise testing (r = .449, p ≤ .001 and r = .435, p ≤ .001), respectively, which is considerably lower than what is seen in older adults and persons with cardiopulmonary diseases.

The 6-min walk test in the functional evaluation of patients with lung cancer qualified for lobectomy

OBJECTIVES

The American College of Chest Physicians guidelines recommend low-technology exercise tests in the functional evaluation of patients with lung cancer considered for resectional surgery. However, the 6-min walk test (6MWT) is not included, because the data on its clinical value are inconsistent. Our goal was to evaluate the 6MWT in assessing the risk of cardiopulmonary complications in candidates for lung resection.

METHODS

We performed a retrospective assessment of clinical data and pulmonary function test results in 947 patients, mean age 65.3 (standard deviation 9.5) years, who underwent a single lobectomy for lung cancer. In 555 patients with predicted postoperative values ≤60%, the 6MWT was performed. The 6-min walking distance (6MWD) and the distance-saturation product (DSP), which is the product of the 6MWD in metres, and the lowest oxygen saturation registered during the test were assessed.

RESULTS

A total of 363 patients with predicted postoperative values <60% and a 6MWT distance (6MWD) ≥400 m or DSP ≥ 350 m% had a lower rate of cardiopulmonary complications than patients with shorter 6MWD or lower DSP values [odds ratio (OR) 0.53, 95% confidence interval (CI) 0.35-0.81] and 0.47 (95% CI 0.30-0.73), respectively. This result was also true for patients with predicted postoperative values <40%, ORs 0.33 (95% CI 0.14-0.79) and 0.25 (95% CI 0.10-0.61), respectively.

CONCLUSIONS

The 6MWT is useful in the assessment of operative risk in patients undergoing a single lobectomy for lung cancer. It helps to stratify the operative risk, which is lower in patients with 6MWD ≥400 m or DSP ≥350 m% than in patients with a shorter 6MWD or lower DSP values.

Agreement between Cardiopulmonary Exercise Test and Modified 6-Min Walk Test in Determining Oxygen Uptake in COPD Patients with Different Severity Stages

BACKGROUND

In moderate-to-severe chronic obstructive pulmonary disease (COPD) patients the 6-min walk test (6MWT) is often exhaustive and correlates with the incremental cycle cardiopulmonary exercise test (CPET).

OBJECTIVES

The aim of this study was to assess the agreement between oxygen uptake (VO2) measured during the 6MWT by portable equipment and incremental cycle exercise in COPD patients with Global Initiative for Chronic Obstructive Lung Disease (GOLD) I-IV.

METHODS

A total of 30 patients with COPD GOLD I-IV (14 patients GOLD stage I and II and 16 patients GOLD stage III and IV) underwent a 6MWT and an incremental CPET. Breath-by-breath analysis for VO2, carbon dioxide output (VCO2), and minute ventilation (VE) were measured during each test. Blood gas analysis and lactate measurements were performed before, during, and after the test.

RESULTS

VO2 in COPD patients GOLD stage I and II was 16.2 ± 4.2 mL/kg/min measured by 6MWT and 20.5 ± 7.0 mL/kg/min measured by CPET as compared to GOLD stage III and IV (11.2 ± 3.7 mL/kg/min measured by 6MWT and 15.5 ± 4.3 mL/kg/min measured by CPET). No significant correlation in VO2 measurements could be found between both tests in COPD GOLD I and II (r = 0.17), whereas the VO2 significantly correlated in patients with COPD stage III and IV (r = 0.7).

CONCLUSIONS

A significant relationship between VO2 measured by 6MWT and CPET could only be found in patients with more severe COPD but not in milder stages. 6MWT and CPET provide different VO2 measurements in COPD patients. The two methods cannot be used interchangeably.

Reliability, Validity, and Responsiveness of the Incremental Shuttle Walk Test in Patients With Interstitial Lung Disease

PURPOSE

To determine the reliability, validity, and responsiveness of the incremental shuttle walk test (ISWT) in patients with interstitial lung disease (ILD).

METHODS

This was a cross-sectional longitudinal study. Patients (n = 27, 10 males; mean age ± SD, 61 ± 9.8 y) with ILD of any etiology, who participated in an outpatient pulmonary rehabilitation (PR) program, were recruited. Reliability was determined by comparing the distance covered in meters between the ISWT-1 and the ISWT-2. Validity was assessed by correlating the distance covered in the ISWT-1, with the maximum oxygen consumption ((Equation is included in full-text article.)O2max) obtained through cardiopulmonary exercise testing and distance covered during the 6-min walk test (6MWT). Responsiveness was assessed by comparing the distance covered in the ISWT-3, undertaken after the completion of PR, to the ISWT-1.

RESULTS

The distance covered was equivalent between the ISWT-1 (216.7 ± 64.9 m) and the ISWT-2 (220.7 ± 67.3 m), with an excellent intraclass correlation coefficient (ICC2,1 = 0.91; 95% CI, 0.81-0.95). The standard error of measurement and minimal detectable change at the 95% CI (MDC95) values for the ISWT were 19.5 m and 53.9m, respectively. There were significant correlations between the distance covered on the ISWT and (Equation is included in full-text article.)O2max (r = 0.79, P < .0001) and the distance covered on the 6MWT (r = 0.76, P < .0001). Following PR, the change in the ISWT distance showed large effect size (ES = 0.85) and standardized response mean (SRM = 1.58).

CONCLUSIONS

The ISWT is a reliable, valid, and responsive measure of estimated functional capacity in patients with ILD.

Ventilatory Support via Mouthpiece to Facilitate Ambulation

OBJECTIVE

The aim of the study was to evaluate the efficacy of noninvasive ventilatory assistance/support via mouthpiece to improve performance in 6-min walk tests for individuals with severe restrictive ventilatory disorders.

DESIGN

Each subject performed the 6-min walk test breathing spontaneously and again while using mouthpiece noninvasive ventilatory assistance/support at full ventilatory support. Oxyhemoglobin saturation (O2 sat), heart rate, Borg scale, distance walked, and ambulation duration were recorded.

RESULTS

Eighteen patients using nocturnal nasal noninvasive ventilatory assistance/support, median (interquartile range) age of 58.5 (20) yrs, were studied. Their median baseline forced vital capacity and PaCO2 were 940 (385) ml and 54.1 (6) mm Hg, respectively. All used noninvasive ventilatory assistance/support for at least overnight hours for 36 (111) mos. Because of the progression of ventilatory impairment and hypercapnia, daytime mouthpiece noninvasive ventilatory assistance/support was initiated. All the 6-min walk test parameters improved significantly by using noninvasive ventilatory assistance/support. Both initial and final values of O2 saturation significantly increased (92% [6] vs 96% [2], P < 0.001) and (80% [19] vs 85.50% [13], P = 0.001), respectively. The median distance walked increased by 43% with noninvasive ventilatory assistance/support (175 [218] m vs 250 [113] m, P = 0.017), and the total ambulation time also increased with noninvasive ventilatory assistance/support (5.45 [3] mins vs. 6 [0] mins, P = 0.008).

CONCLUSIONS

The exercise tolerance of patients with severe ventilatory impairment can improve by using noninvasive ventilatory support.

Reference values for the 6-min walk test in healthy middle-aged and older adults: from the total distance traveled to physiological responses

Abstract Introduction: Physiological responses to the 6-min walk test (6MWT) have been increasingly evaluated in patients with cardiopulmonary diseases. However, previous studies did not include healthy persons. Objective: To evaluate the intensity of 6MWT, to develop a series of predictive equations for the physiological variables and to test their reliability in healthy middle-aged and older adults. Method: We evaluated 102 non-trained healthy adults (54 women, aged 61 ± 10 years) and a cross-validation sample of 30 participants. We measured physiological responses to the 6MWT and a cardiopulmonary exercise testing (CPET) on a treadmill. Results: The R2 values for regression analysis adjusted by age, body mass, stature, and sex ranged from 0.25 for heart rate and 0.46 for peak V ˙ O 2 The 6MWT distance and 6MWT peak V ˙ O 2 represented 110 ± 10% and 102 ± 15% of the predicted values, respectively, using our equations. The intensity of 6MWT corresponded to 72 ± 13% of the peak O2 and 78 ± 23% of the peak HR in the CPET. Peak V ˙ O 2 in the CPET was adequately predicted by 6MWT peak V ˙ O 2 (R2 = 0.76) and 6MWD (R2 = 0.54). Conclusion: The 6MWT represents a moderate to high-intensity test in middle-aged and older healthy adults and is valid for assessing maximal aerobic exercise capacity. Physiological responses to the 6MWT may be adequately predicted with a combination of anthropometrics and demographics.

A comparative study of the five-repetition sit-to-stand test and the 30-second sit-to-stand test to assess exercise tolerance in COPD patients

Purpose

The sit-to-stand test (STST) has been used to evaluate the exercise tolerance of patients with COPD. However, mutual comparisons to predict poor exercise tolerance have been hindered by the variety of STST modes used in previous studies, which also did not consider patients’ subjective perceptions of different STST modes. Our aim was to compare the five-repetition sit-to-stand test (5STS) with the 30-second sit-to-stand test (30STS) for predicting poor performance in the six-minute walking test and to evaluate patients’ subjective perceptions to determine the optimal mode for clinical practice.

Patients and methods

Patients with stable COPD performed 5STS, 30STS and the 6MWT and then evaluated their feelings about the two STST modes by Borg dyspnea score and a questionnaire. Moreover, we collected data through the pulmonary function test, mMRC dyspnea score, COPD assessment test and quadriceps muscle strength (QMS). A receiver operating characteristic curve analysis of the 5STS and 30STS results was used to predict 6-minute walk distance (6MWD) <350 m.

Results

The final analysis included 128 patients. Similar moderate correlations were observed between 6MWT and 5STS (r=−0.508, P<0.001) and between 6MWT and 30STS (r=0.528, P<0.001), and there were similar correlations between QMS and 5STS (r=−0.401, P<0.001) and between QMS and 30STS (r=0.398, P<0.001). The 5STS and 30STS score cutoffs produced sensitivity, specificity and positive and negative predictive values of 76.0%, 62.8%, 56.7% and 80.3% (5STS) and 62.0%, 75.0%, 62.0% and 75.0% (30STS), respectively, for predicting poor 6MWT performance. The 5STS exhibited obvious superiority in terms of the completion rate and the subjective feelings of the participants.

Conclusion

As a primary screening test for predicting poor 6MWD, the 5STS is similar to the 30STS in terms of sensitivity and specificity, but the 5STS has a better patient experience.

Six minute walk test versus incremental shuttle walk test in cystic fibrosis

BACKGROUND

Although both self-paced and externally paced field tests are widely used in cystic fibrosis (CF), it is still unclear whether they induce clinically relevant and similar cardiorespiratory responses. The aim of this study was therefore to compare the incremental shuttle walk test (ISWT) and 6 min walk test (6MWT), and to determine the factors influencing exercise capacity in CF.

METHODS

Fifty clinically stable CF patients were included in the study. Pulmonary function, peripheral and respiratory muscle strength were assessed, anthropometric measurements were recorded, and 6MWT and ISWT carried out.

RESULTS

The CF patients covered significantly more distance in the ISWT than 6MWT (P < 0.001). Heart rate response and dyspnea score at the end of the tests and during the recovery phase were significantly higher in the ISWT compared with the 6MWT (P < 0.05). The 6MWT and ISWT had similar moderate-strong correlations with age, height, weight, pulmonary function, respiratory and peripheral muscle strength (P < 0.05). Forty-nine percent of the variance in 6MWT distance was explained by age and forced expiratory volume in 1 s (FEV1 ; R(2)  = 0.49, F(2-48) = 22.033, P < 0.001). The variables contributing to ISWT distance were FEV1 , inspiratory muscle strength, and body mass index (R(2)  = 0.596, F(3-44) = 20.176, P < 0.001).

CONCLUSIONS

The ISWT is a better reflection of exercise tolerance in CF than 6MWT. ISWT is a preferable alternative assessment of exercise tolerance in terms of cardiorespiratory response.

Comparison of the six-minute walk test with a cycle-based cardiopulmonary exercise test in people following curative intent treatment for non-small cell lung cancer

This study is aimed to (i) compare both the magnitude of impairment in exercise capacity and exercise responses measured during the six-minute walk test (6MWT) and the cardiopulmonary exercise test (CPET) and (ii) investigate the effect of test repetition on six-minute walk distance (6MWD) in people following curative intent treatment for non-small cell lung cancer (NSCLC). Twenty participants (67 ± 10 years; 14 females), 6-10 weeks following lobectomy, underwent a CPET and two 6MWTs. Peak exercise responses, dyspnoea and leg fatigue, as well as heart rate (HR) and oxygen saturation (SpO2) during the 6MWT, were compared to those during the CPET. Compared with exercise capacity when expressed as peak rate of oxygen consumption (%pred) measured during the CPET, exercise capacity when expressed as 6MWD (%pred) was less impaired (81 ± 10 vs. 63 ± 15 %pred; p < 0.001). Compared with the CPET, the 6MWT elicited lower peak HR (119 ± 15 vs. 128 ± 18 beats minute(-1); p = 0.02), lower SpO2 (93 ± 2 vs. 95 ± 3%; p < 0.05), less dyspnoea (3.1 ± 1.6 vs. 6.9 ± 2.6; p < 0.01) and less leg fatigue (2.0 ± 1.9 vs. 6.8 ± 2.4; p < 0.01). The 6MWD increased 19 ± 19 metre (4 ± 4%) with test repetition (p < 0.001). In people following curative intent treatment for NSCLC, the 6MWT appears to elicit sub-maximal exercise responses when compared with the CPET. There is a significant effect of test repetition on 6MWD.

Validity of the six-minute step test of free cadence in patients with chronic obstructive pulmonary disease

Objectives:

to evaluate the concurrent validity of the six-minute step test (6MST) in assessing exercise capacity of COPD patients using the six-minute walk test (6MWT) as a gold-standard. The predictive validity of the 6MST was assessed to determine a cut-off point for identification of low exercise capacity.

Method:

thirty-two COPD patients (50-87 years old) with mild to very severe obstruction performed the 6MST and 6MWT twice.

Results:

Concurrent validity: a strong positive correlation (Pearson) between the number of ascents on the first (T1), second (T2) and the best of both (T1 or T2) tests during the 6MWT was observed. Although a moderate negative correlation with BODE index and FEV₁ was found, it was considered insufficient to test the validity, therefore ROC curves were not applied. The predictive validity (ROC) of the 6MST to identify low physical capacity (compared with the 6MWT) using the performance of T1 or T2, or solely T1 was considered accurate, and the area under the curve was 0.8 (IC95% 0.62-0.98) and 0.85 (IC95% 0.70-0.99), respectively. To classify patients, the cut-off points of 86 and 78 steps were chosen, with both values showing 90% of sensitivity and specificity of 64% and 68% for T1 or T2, or solely T1, respectively.

Conclusion:

The number of steps on the 6MST was valid to verify exercise capacity in COPD patients and the cut-off point of 78 steps was able to identify patients with poor exercise tolerance. Values under this cut-off point are considered to identify patients with a poorer prognosis.

Six-minute stepper test: a valid clinical exercise tolerance test for COPD patients

Introduction

Exercise tolerance testing is an integral part of the pulmonary rehabilitation (PR) management of patients with chronic obstructive pulmonary disease (COPD). The 6-minute stepper test (6MST) is a new, well-tolerated, reproducible exercise test, which can be performed without any spatial constraints.

Objective

The aim of this study was to compare the results of the 6MST to those obtained during a 6-minute walk test (6MWT) and cardiopulmonary exercise testing (CPET) in a cohort of COPD patients.

Methods

Ninety-one COPD patients managed by outpatient PR and assessed by 6MST, 6MWT, and CPET were retrospectively included in this study. Correlations between the number of steps on the 6MST, the distance covered on the 6MWT, oxygen consumption, and power at the ventilatory threshold and at maximum effort during CPET were analyzed before starting PR, and the improvement on the 6MST and 6MWT was compared after PR.

Results

The number of steps on the 6MST was significantly correlated with the distance covered on the 6MWT (r=0.56; P<0.0001), the power at maximum effort (r=0.46; P<0.0001), and oxygen consumption at maximum effort (r=0.39; P<0.005). Performances on the 6MST and 6MWT were significantly improved after PR (570 vs 488 steps, P=0.001 and 448 vs 406 m, respectively; P<0.0001). Improvements of the 6MST and 6MWT after PR were significantly correlated (r=0.34; P=0.03).

Conclusion

The results of this study show that the 6MST is a valid test to evaluate exercise tolerance in COPD patients. The use of this test in clinical practice appears to be particularly relevant for the assessment of patients managed by home PR.

A randomised controlled trial of supplemental oxygen versus medical air during exercise training in people with chronic obstructive pulmonary disease: supplemental oxygen in pulmonary rehabilitation trial (SuppORT) (Protocol)

BACKGROUND

Oxygen desaturation during exercise is common in people with chronic obstructive pulmonary disease (COPD). The aim of the study is to determine, in people with COPD who desaturate during exercise, whether supplemental oxygen during an eight-week exercise training program is more effective than medical air (sham intervention) in improving exercise capacity and health-related quality of life both at the completion of training and at six-month follow up.

METHODS/DESIGN

This is a multi-centre randomised controlled trial with concealed allocation, blinding of participants, exercise trainers and assessors, and intention-to-treat analysis. 110 people with chronic obstructive pulmonary disease who demonstrate oxygen desaturation lower than 90 % during the six-minute walk test will be recruited from pulmonary rehabilitation programs in seven teaching hospitals in Australia. People with chronic obstructive pulmonary disease on long term oxygen therapy will be excluded. After confirmation of eligibility and baseline assessment, participants will be randomised to receive either supplemental oxygen or medical air during an eight-week supervised treadmill and cycle exercise training program, three times per week for eight weeks, in hospital outpatient settings. Primary outcome measures will be endurance walking capacity assessed by the endurance shuttle walk test and health-related quality of life assessed by the Chronic Respiratory Disease Questionnaire. Secondary outcomes will include peak walking capacity measured by the incremental shuttle walk test, dyspnoea via the Dyspnoea-12 questionnaire and physical activity levels measured over seven days using an activity monitor. All outcomes will be measured at baseline, completion of training and at six-month follow up.

DISCUSSION

Exercise training is an essential component of pulmonary rehabilitation for people with COPD. This study will determine whether supplemental oxygen during exercise training is more effective than medical air in improving exercise capacity and health-related quality of life in people with COPD who desaturate during exercise.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry ACTRN12612000395831, 5th Jan,2012.

Are cardiovascular and metabolic responses to field walking tests interchangeable and obesity-dependent?

PURPOSE

To investigate if cardiovascular and metabolic responses to the six-minute walk test (6MWT) and incremental shuttle walking test (ISWT) are in agreement with cardiopulmonary exercise testing (CPX) and determine if both submaximal tests are interchangeable in obese and eutrophic individuals.

METHOD

Observational and cross-sectional study included 51 obese women (ObG) and 21 controls (CG) (20-45 years old). Subjects underwent clinical evaluation, CPX, the 6MWT and ISWT. We applied Bland-Altman plots to assess agreement between walking tests and CPX. Correlation analysis assessed relationships between key variables.

RESULTS

There was an agreement between CPX and both the 6MWT [oxygen uptake (VO2 mL kg(-1) min(-1)) = 6.9 (CI: 5.7-8.1), and heart rate (bpm) = 37.0 (CI: 33.3-40.7)] and ISWT [VO2 (mL kg(-1) min(-1)) = 6.1 (CI: 4.9-7.3), and heart rate (bpm) = 36.2 (CI: 32.1-40.3)]. We found similar cardiovascular and metabolic responses to both tests in the ObG but not in the CG. Strong correlations were demonstrated between 6MWT and ISWT variables: VO2 ( r = 0.70); dyspnoea (r = 0.80); and leg fatigue (r = 0.70).

CONCLUSIONS

6MWT and ISWT may both hold interchangeable clinical value when contrasted with CPX in obese women and may be a viable alternative in the clinical setting when resources and staffing are limited. Implications for Rehabilitation Obesity is a worldwide epidemic, with high prevalence in women, and it is associated to impaired cardiorespiratory fitness and functional capacity as well as high mortality risk. Assessing oxygen uptake by means of cardiopulmonary exercise testing is the gold standard method for evaluating and stratifying cardiorespiratory fitness, however it is not ever applied due to costs and staffing. Walking field tests may be a cost-effective approach that provides valuable information regarding the functional capacity in agreement to metabolic and cardiovascular responses of cardiopulmonary exercise testing.

Systematic Review of the Association Between Laboratory- and Field-Based Exercise Tests and Lung Function in Patients with Chronic Obstructive Pulmonary Disease

Introduction: Typical symptoms of chronic obstructive pulmonary disease (COPD) include breathlessness and reduced exercise capacity. Several laboratory- and field-based exercise tests are used to assess the exercise capacity of patients with COPD. It is unclear whether these exercise tests reflect the spirometric measures recommended for diagnosis of COPD. We therefore aimed to systematically assess the correlation between these exercise tests and common measures of lung function. Methods: A search of Embase™, MEDLINE^® and The Cochrane Library identified primary publications in English that reported data on the correlations (Pearson's r or Spearman's rho) between the outcomes of exercise tests and the physiological measures of interest: forced expiratory volume in 1 second (FEV₁), forced vital capacity, inspiratory capacity and arterial oxygen saturation. We included studies reporting on the following exercise tests: 6- and 12-minute walk tests (6MWT and 12 MWT), incremental and endurance shuttle walk tests, incremental and endurance cycle ergometer tests, and treadmill tests. Results: Of 1781 articles screened, 45 were ultimately deemed eligible for inclusion in this review. The most commonly reported lung function variable was FEV₁ (reported by 39 studies); the most commonly reported exercise test was the 6-minute walk test (reported by 24 studies). FEV₁ appears to correlate moderately-to-strongly with 6MWT and 12MWT; and moderately-to-very strongly with incremental cycle ergometer tests (ICET); evidence for other exercise tests was limited. Conclusion: There is evidence that 6MWT, 12MWT and ICET correlate with FEV₁ to some degree; - evidence for associations of other exercise tests with measures of lung function in patients with COPD is limited. Clinicians must consider this when deciding to use these tests. Further comparisons of these tests must be made in order to assess which physiological and hemodynamic characteristics they reflect in patients with COPD.

Intensity and physiological responses to the 6-minute walk test in middle-aged and older adults: a comparison with cardiopulmonary exercise testing

The 6-minute walk test (6MWT) is a simple field test that is widely used in clinical settings to assess functional exercise capacity. However, studies with healthy subjects are scarce. We hypothesized that the 6MWT might be useful to assess exercise capacity in healthy subjects. The purpose of this study was to evaluate 6MWT intensity in middle-aged and older adults, as well as to develop a simple equation to predict oxygen uptake (V˙O2) from the 6-min walk distance (6MWD). Eighty-six participants, 40 men and 46 women, 40-74 years of age and with a mean body mass index of 28±6 kg/m², performed the 6MWT according to American Thoracic Society guidelines. Physiological responses were evaluated during the 6MWT using a K4b2 Cosmed telemetry gas analyzer. On a different occasion, the subjects performed ramp protocol cardiopulmonary exercise testing (CPET) on a treadmill. Peak V˙O2 in the 6MWT corresponded to 78±13% of the peak V˙O2 during CPET, and the maximum heart rate corresponded to 80±23% of that obtained in CPET. Peak V˙O2 in CPET was adequately predicted by the 6MWD by a linear regression equation: V˙O2 mL·min^-1·kg^-1 = -2.863 + (0.0563×6MWD_m) (R²=0.76). The 6MWT represents a moderate-to-high intensity activity in middle-aged and older adults and proved to be useful for predicting cardiorespiratory fitness in the present study. Our results suggest that the 6MWT may also be useful in asymptomatic individuals, and its use in walk-based conditioning programs should be encouraged.

Reliability of peak O2 uptake and O2 uptake kinetics in step exercise tests in healthy subjects

To date little is known about the reliability of peak oxygen consumption (V˙O2PEAK) in incremental metronome paced step tests (IST) and the reliability of on-kinetics V˙O2 has never been studied. We aimed to study the reliability of both tests. Eleven healthy subjects performed two ISTs until exhaustion. On two different days two duplicate 4min constant metronome paced step tests (CST) were performed. V˙O2PEAK, mean response time (MRT) and phase II time constant (τ) were tested for reproducibility using the paired t-tests, in addition to the limits of agreement (LOA) and within subject coefficient of variation (COV). With a 95% LOA of 0.38 to 0.26Lmin(-1), -8.7 to 9.1s and -9.9 to 10.5s they exhibit a COV of 3%, 4.5% and 6.9% for V˙O2PEAK, MRT and τ respectively. ST are sufficiently reliable for maximal and submaximal aerobic power assessments in healthy subjects and new studies of oxygen uptake kinetics in selected patient groups are warranted.

Examining the role of activity, exercise, and pharmacology in mild COPD

Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality worldwide and, although it is a preventable and treatable disease, it often remains undiagnosed in patients with mild disease. It is now evident that pathologic changes and physiologic impairment start early in disease progression, and even patients with mild airflow limitation have impairment in the form of exertional dyspnea, general fatigue, and exercise intolerance. Primary care physicians are optimally positioned to recognize these progressive activity restrictions in their patients, usually involving little more than a detailed patient history and a simple symptom questionnaire. Once a patient with persistent activity-related dyspnea has been diagnosed with COPD, bronchodilators can effectively address expiratory airflow limitation and lung hyperinflation that underlie symptoms. These pharmacologic interventions work in conjunction with nonpharmacologic interventions, including smoking cessation, exercise training, and pulmonary rehabilitation. Although the benefits of exercise intervention are well established in patients with more severe COPD, a small amount of new data is emerging that supports the benefits of both pharmacologic treatment and exercise training for improving exercise endurance in patients with mild-to-moderate COPD. This review examines the growing body of data that suggests that early identification-most likely by primary care physicians-and appropriate intervention can favorably impact the symptoms, exercise tolerance, health status, quality of life, hospitalizations, and economic costs of COPD.

Measurement properties of the incremental shuttle walk test. a systematic review

Background: The incremental shuttle walk test (ISWT) was developed > 20 years ago and has been used to assess peak exercise capacity in a variety of chronic diseases. The aim of this systematic review is to describe the measurement properties of the ISWT in a clinical population.Methods: Of 800 articles identified by electronic and hand searches, 35 were included. Twenty-one articles included data on the validity of the ISWT, 18 on the reliability, four on the responsiveness,and four on the interpretability.Results: Most of the studies were conducted in patients with COPD (n = 13) or cardiac disease(n = 8). For criterion validity, comparisons between distance covered during the ISWT and peak oxygen consumption reported correlations ranging from 0.67 to 0.95 ( P <.01). Intraclass correlation coefficients for test-retest reliability ranged from 0.76 to 0.99. The ISWT was shown to be responsive to pulmonary rehabilitation and bronchodilator administration. The minimal clinically important difference (MCID) in patients with COPD was 48 m. Predictive equations for the distance in the ISWT are available for healthy individuals.Conclusions: The ISWT can be considered a valid and reliable test to assess maximal exercise capacity in individuals with chronic respiratory diseases. The ISWT has been shown to be responsive to pulmonary rehabilitation and bronchodilator use in individuals with COPD, cystic fibrosis,and asthma. Further studies examining responsiveness and the MCID of the ISWT in patients with conditions other than lung diseases are required for the interpretation of interventions in other populations.

An official European Respiratory Society/American Thoracic Society technical standard: field walking tests in chronic respiratory disease

Field walking tests are commonly employed to evaluate exercise capacity, assess prognosis and evaluate treatment response in chronic respiratory diseases. In recent years, there has been a wealth of new literature pertinent to the conduct of the 6-min walk test (6MWT), and a growing evidence base describing the incremental and endurance shuttle walk tests (ISWT and ESWT, respectively). The aim of this document is to describe the standard operating procedures for the 6MWT, ISWT and ESWT, which can be consistently employed by clinicians and researchers. The Technical Standard was developed by a multidisciplinary and international group of clinicians and researchers with expertise in the application of field walking tests. The procedures are underpinned by a concurrent systematic review of literature relevant to measurement properties and test conduct in adults with chronic respiratory disease. Current data confirm that the 6MWT, ISWT and ESWT are valid, reliable and responsive to change with some interventions. However, results are sensitive to small changes in methodology. It is important that two tests are conducted for the 6MWT and ISWT. This Technical Standard for field walking tests reflects current evidence regarding procedures that should be used to achieve robust results.

An official systematic review of the European Respiratory Society/American Thoracic Society: measurement properties of field walking tests in chronic respiratory disease

This systematic review examined the measurement properties of the 6-min walk test (6MWT), incremental shuttle walk test (ISWT) and endurance shuttle walk test (ESWT) in adults with chronic respiratory disease.

Studies that report the evaluation or use of the 6MWT, ISWT or ESWT were included. We searched electronic databases for studies published between January 2000 and September 2013.

The 6-min walking distance (6MWD) is a reliable measure (intra-class correlation coefficients ranged from 0.82 to 0.99 in seven studies). There is a learning effect, with greater distance walked on the second test (pooled mean improvement of 26 m in 13 studies). Reliability was similar for ISWT and ESWT, with a learning effect also evident for ISWT (pooled mean improvement of 20 m in six studies). The 6MWD correlates more strongly with peak work capacity (r=0.59–0.93) and physical activity (r=0.40–0.85) than with respiratory function (r=0.10–0.59). Methodological factors affecting 6MWD include track length, encouragement, supplemental oxygen and walking aids. Supplemental oxygen also affects ISWT and ESWT performance. Responsiveness was moderate to high for all tests, with greater responsiveness to interventions that included exercise training.

The findings of this review demonstrate that the 6MWT, ISWT and ESWT are robust tests of functional exercise capacity in adults with chronic respiratory disease.

Estimating endurance shuttle walk test speed using the six-minute walk test in people with chronic obstructive pulmonary disease

The objective of this study was to derive and validate an equation to estimate the speed for the endurance shuttle walk test (ESWT) using results from the six-minute walk test (6MWT) in patients with chronic obstructive pulmonary disease (COPD). Participants with diagnosed COPD (n = 84) performed two incremental shuttle walk tests (ISWTs) and two 6MWTs. ESWT speed was calculated from the ISWT results using the original published method. An equation was derived, which directly related six-minute walk distance (6MWD) to ESWT speed. The derived equation was validated in a different group of people with COPD (n = 52). There was a strong correlation between average 6MWD and the calculated ESWT speed (r = 0.88, p < 0.001). The ESWT speed (kilometre per hour) was estimated using the following equation: 0.4889 + (0.0083 × 6MWD). The mean difference (±limits of agreement) between ESWT speeds was calculated using the original published method and found to be 0.03 (±0.77) km/hour. When the ISWT is not the test of choice for clinicians, the 6MWT can be used to accurately estimate the speed for the ESWT.

Two-step stool aerobic training for smokers

OBJECTIVE

The aim of this study was to analyze subjective, physical, and physiologic responses to a standardized incremental 30-min two-step stool test to create an individualized 45-min maximally intensive two-step stool endurance exercise regimen for home training.

DESIGN

This is a longitudinal study on 26 consecutively referred male smokers aged 39-66 yrs. Each performed the two-step stool test on two 15-cm steps at 10, 20, 30, 40, 50, and 60 climbs per minute. Exertional dyspnea, oxygen consumption per unit time, ventilation, respiratory rate, tidal volume, heart rate, capillary oxyhemoglobin saturation, physiologic cost index, and oxygen pulse were recorded and compared with those observed during incremental cycle exercise (30 W per 3 mins). Multivariate analysis for each parameter was undertaken as a mixed model.

RESULTS

All subjects attained 60 climbs per minute on the two-step stool test and performed 38-42 mins of two-step stool endurance. All parameters reached 80%-96% of cycle maximum oxygen consumption. The subjects found the two-step stool endurance simple and practical to perform at home. There were no complications.

CONCLUSIONS

The incremental two-step stool test is a simple, cost-effective way to establish a 45-min maximally intensive endurance exercise training program practical for use in the home.

Reference values for the incremental shuttle walk test in healthy subjects: from the walk distance to physiological responses

OBJECTIVE:

To determine reference values for incremental shuttle walk distance (ISWD) and peak physiological responses during the incremental shuttle walk test (ISWT), as well as to develop a series of predictive equations for those variables in healthy adults.

METHODS:

We evaluated 103 healthy participants ≥ 40 years of age (54 women and 49 men). We fitted each participant with a gas analysis system for use during the ISWT. Oxygen consumption (VO₂), carbon dioxide production, minute ventilation, heart rate (HR), ISWD, and maximal walking velocity (MWV) were obtained as primary outcomes. We also assessed hand grip strength (HGS) and lean body mass (LBM).

RESULTS:

The regression analysis models, including physiological variables, ISWD, and MWV (adjusted for age, body mass, height, and sex), produced R² values ranging from 0.40 to 0.65 (for HR and peak VO₂, respectively). Using the models including LBM or HGS, we obtained no significant increase in the R² values for predicting peak VO₂, although the use of those models did result in slight increases in the R² values for ISWD and MWV (of 8% and 12%, respectively). The variables ISWD, MWV, and ISWD × body mass, respectively, explained 76.7%, 73.3%, and 81.2% of peak VO₂ variability.

CONCLUSIONS:

Our results provide reference values for ISWD and physiological responses to the ISWT, which can be properly estimated by determining simple demographic and anthropometric characteristics in healthy adults ≥ 40 years of age. The ISWT could be used in assessing physical fitness in the general adult population and in designing individualized walking programs.