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

Procedures and measurement properties of the 6-min step test: A systematic review with clinical recommendations

OBJECTIVE

To provide information regarding the procedures, safety, tolerability, and measurement properties of the 6-min step test.

DATA SOURCES

MEDLINE, EMBASE, CINAHL, and SPORTDiscus (from inception until January 2024).

REVIEW METHODS

Studies that examined adults with acute or chronic diseases, and outcomes related to procedures, safety, tolerability, or measurement properties of the 6-min step test were included. Outcome data were summarized and combined in meta-analyses. The quality of included studies was assessed by the Consensus-based Standards for the selection of health Measurement Instruments checklist, and the quality of evidence was determined according to the Grading of Recommendations Assessment, Development, and Evaluation system.

RESULTS

Fourteen studies, involving 847 participants, were included. All studies performed the 6-min step test in 6 min; however, some studies varied the step height and the use of upper limb support. The test appears to be safe and well tolerated by individuals. Moderate- to high-quality evidence demonstrated appropriate results for test-retest reliability (4 studies; Intraclass correlation coefficient 0.96; 95% CI 0.91-0.98; n = 125), criterion validity (4 studies; r = 0.53; 95% CI 0.30-0.71; n = 307), and construct validity (4 studies; r = 0.63; 95% CI 0.52-0.73; n = 233).

CONCLUSION

This review provides recommendations for applying the 6-min step test in clinical and research settings. No adverse events were reported, and the test appears to be well tolerated. Adequate results were found for test-retest reliability, criterion validity, and construct validity.

REVIEW REGISTRATION

PROSPERO (CRD42022347744).

The six-minute step test can predict COPD exacerbations: a 36-month follow-up study

The six-minute step test (6MST) has been shown to be effective in assessing exercise capacity in individuals with COPD regardless of severity and, despite its easy execution, accessibility and validity, information on the prognostic power of this test remains uncertain. The aim of this study is to investigate whether the 6MST can predict the occurrence of exacerbations in patients with COPD. This is a prospective cohort study with a 36-month follow-up in patients with COPD. All patients completed a clinical assessment, followed by pulmonary function testing and a 6MST. The 6MST was performed on a 20 cm high step; heart rate, blood pressure, oxygen saturation, BORG dyspnea and fatigue were collected. Sixty-four patients were included in the study, the majority being elderly men. Performance on the 6MST demonstrated lower performance compared to normative values proposed in the literature, indicating a reduced functional capacity. Kaplan Meier analysis revealed that ≤ 59 steps climbed during the 6MST was a strong predictor of COPD exacerbation over a 36-month follow-up. We have identified a minimal threshold number of steps (≤ 59) obtained through the 6MST may be able predict the risk of exacerbations in patients with COPD.

Effects of a cardiopulmonary telerehabilitation using functional exercises in individuals after COVID-19 hospital discharge: A randomized controlled trial

INTRODUCTION

Individuals with severe coronavirus disease 2019 (COVID-19) may present respiratory and motor complications, requiring rehabilitation programs (RP) for long periods. However, access to cardiopulmonary rehabilitation is poor. Cardiopulmonary telerehabilitation is an alternative for cardiopulmonary dysfunction, improving functional capacity, dyspnea, and quality of life. Moreover, few clinical trials verified the effectiveness of telerehabilitation using functional exercise for post-COVID symptoms. Thus, the present study aimed to verify the effects of cardiopulmonary telerehabilitation using functional and accessible exercises in individuals after COVID-19 hospital discharge.

METHODS

This blinded, randomized, and controlled clinical trial and included 67 adult individuals after COVID-19 hospital discharge. Participants were randomized into the groups of telerehabilitation (TG; n = 33) and control (CG; n = 34). TG underwent an individualized exercise program (functional and accessible exercises) supervised by a physical therapist (videoconference), and CG received guidance on general care and self-monitoring of vital signs (videoconference). The primary outcome was performance and physiological responses on the 6-minute step test (6MST). Secondary outcomes were performance on the 2-minute stationary walk test (2MSWT), 30-second chair stand test (30CST), and quality of life using the 36-Item Short Form Health Survey (SF-36) questionnaire physical functioning concept (PF).

RESULTS

Functional capacity (6MST) improved by 28 ± 17 steps in TG and 15 ± 26 in CG (p = 0.04). For secondary outcomes, performance on 2MSWT increased by 39 ± 6 steps in TG and 10 ± 6 in CG (p = 0.00); 30CST by 3 ± 1 repetitions in TG and 1.5 ± 0.5 in CG (p = 0.05); and PF (SF-36) by 17 ± 4 points in TG and 12 ± 4 in CG (p = 0.00). Also, peak oxygen uptake VO2peak (6MST) improved by 3.8 ± 1 mL min-1 kg-1 in TG and 4.1 ± 1 in CG (p = 0.6), and heart rate demand (6MST) by 11 ± 37% in TG and -4 ± 19% in CG (p = 0.04).

CONCLUSIONS

Cardiopulmonary telerehabilitation using functional exercises improved the exercise and functional capacity assessed using 6MST, 30CST, and 2MSWT and the quality of life of individuals after COVID-19 hospital discharge.

Cardiorespiratory Response to Six-Minute Step Test in Post COVID-19 Patients-A Cross Sectional Study

BACKGROUND AND PURPOSE

New coronavirus disease 2019 (COVID-19) can cause persistent symptoms and physical weakness that can lead to a limitation in activities of daily living (ADL). There is a lack of evidence about the performance in the six-minute step test (6MST) of post-COVID-19 patients and healthy subjects. The aim of this study is to investigate the cardiorespiratory response induced by the 6MST in post-COVID-19 patients and compare it with the response of the six-minute walk test (6MWT).

METHODS

This cross-sectional study was conducted on 34 post-COVID-19 patients and 33 healthy subjects. The assessment was performed at one month from a non-severe SARS-CoV-2 infection. Both groups were assessed by using the 6MST, 6MWT, and the pulmonary function test (PFT). Post COVID functional status (PCFS) scale was used for the post-COVID-19 group to assess functional status. Physiological responses; heart rate (HR), respiratory rate (RR), oxygen saturation (SpO₂), blood pressure (BP), and Borg scale for fatigue and dyspnea were recorded before and after the 6MST and 6MWT.

RESULTS

the performance of the post-COVID-19 group was worse than the healthy group in both tests. In 6MWT, the distance walked by the post-COVID-19 group (423 ± 7) was 94 m less than the healthy group, and the number of climbed steps in the 6MST (121 ± 4) was 34 steps less than the healthy group. Both results were statistically significant (p < 0.001). There was a moderate positive correlation between the 6MST and 6MWT in walked distance versus steps number (r = 0.5, p < 0.001). In addition, there was a moderate correlation between the two tests in the post (HR, RR, SpO₂, systolic blood pressure SBP, diastolic blood pressure DBP, dyspnea, and fatigue) with p < 0.001.

CONCLUSIONS

Six-minute step tests produced similar cardiorespiratory responses when compared to a 6MWT. The 6MST can be used as an assessment tool for COVID-19 patients to evaluate their functional capacity and ADL.

Is the six-minute step test able to reflect the severity and symptoms based on cat score?

BACKGROUND

This is the first study to investigate the performance of 6MST in COPD patients divided into different symptom severity groups based on the CAT questionnaire score.

OBJECTIVES

To evaluate the relationship between the degree symptomatology using the chronic obstructive pulmonary disease (COPD) Assessment Test (CAT) with the six- minute step test (6MST) in COPD patients.

METHODS

This is a cross-sectional study in which 59 patients with COPD were evaluated. The groups were stratified according to the subsequent cutoff points: CAT <10 (little impact) n= 22; CAT 11-20 (moderate impact) n=20; CAT <20 (large impact) n=17. During 6MST the individuals were instructed to go up and down a single step with a height of 20 centimeters (cm).

RESULTS

Comparing the groups in relation to performance on the 6MST, the number of climbs on the step were significantly higher in the CAT group <10 when compared to the CAT group >20, the variation in HR between rest and peak exercise (∆ HRpeak- rest) was lower in the CAT>20 group compared to the CAT<10 group and the CAT 11- 20 group. We found direct relationships between the number of ascents and descents in the 6MST vs the CAT score (r=0.35, p=0.007); and 6MST vs degree of obstruction of %FEV1 (r-0.46, p=0.002) We verified a linear regression model in which the FEV1 (L) and the CAT score influenced 29% in the performance of the 6MST.

CONCLUSION

The COPD severity represented by the FEV₁ and the CAT score are associated and influenced by 29% the performance of 6-minute step test. Our findings may have important implications for the clinical evaluation of these patients as well as for rehabilitation.

Six-minute stepper test for evaluating functional exercise capacity in patients with sarcoidosis

BACKGROUND

Researchers and clinicians may benefit from alternative tests that do not require large physical spaces or corridors for simply evaluating functional exercise capacity in the clinical practice.

OBJECTIVE

Aim of this study was to investigate whether six-minute stepper test (6MST) is a valid tool for measuring functional exercise capacity in patients with sarcoidosis.

METHODS

Thirty-six patients with sarcoidosis and 18 healthy controls were evaluated with 6MST and six-minute walk test (6MWT). Patients performed 6MST twice. Cardiovascular and symptom responses to tests including heart rate, blood pressure, SpO₂, levels of dyspnea and fatigue were recorded.

RESULTS

Receiver operating characteristic (ROC) curve analysis revealed an area under the ROC curve of 0.74 for 6MST in identifying the patients and controls, indicating acceptable discriminative ability. Patients performed significantly worse in 6MST compared to controls (277±54 vs 349±87 steps; p<0.001). 6MST was able to explain 66% of variance in 6MWT (p<0.001), and there was a strong relationship between 6MWT and 6MST (r = 0.812). SpO₂ responses to tests were similar, however, 6MST generated more severe heart rate, dyspnea and fatigue responses. Intraclass correlation coefficient calculated for initial and retest scores of 6MST was 0.990, indicating excellent test-retest reliability. However, there was a systematical improvement (∼4%) in retest 6MST scores.

CONCLUSIONS

6MST is a valid and reliable alternative test for measuring functional exercise capacity in sarcoidosis. 6MST may also help better testing the upper limits of cardiac system and physical endurance as it is more physically demanding than 6MWT.

Efficacy of neuromuscular electrical stimulation with combined low and high frequencies on body composition, peripheral muscle function and exercise tolerance in patients with chronic kidney disease undergoing haemodialysis: a protocol for a randomised, double-blind clinical trial

INTRODUCTION

Neuromuscular electrical stimulation (NMES) as an adjunctive strategy to increase isolated muscular strength or endurance has been widely investigated in patients with chronic kidney disease (CKD) undergoing haemodialysis (HD). However, the efficacy of combined low and high frequencies, to improve both muscular strength and endurance, is unknown. This trial aims to evaluate the efficacy of this combined NMES strategy in this population.

METHODS AND ANALYSIS

This is a randomised controlled trial with blinded assessments and analysis. A total of 56 patients with CKD undergoing HD will be recruited and randomised to an NMES protocol. The evaluations will be performed on three different days at baseline and after 24 sessions of follow-up. Assessments will include the background, insulin-like growth factor, lactate measurement, malnutrition and inflammation score evaluation, an electrical bioimpedance examination, global muscular evaluation by means of the Medical Research Council scale, handgrip strength evaluation, muscular isokinetic evaluation of lower limbs, 6 min step test performance and quality of life (QoL) questionnaire with emphasis on physical function. The patients will be allocated in one of the following four groups: 1) combined low and high frequencies; 2) low frequency; 3) high frequency; and 4) sham stimulation with minimal intensity to generate only sensory perception (with no visible contraction). In all groups, the intensity throughout the session will be the highest tolerated by patient (except for control group). The primary endpoint is the change of peripheral muscle function (muscular strength and endurance). The secondary endpoints will be the changes of body composition; muscle trophism; exercise tolerance; QoL; and nutritional, inflammatory, and metabolic markers. The findings of this study are expected to provide valuable knowledge on how to optimise the NMES intervention, with improvements in both muscle strength and endurance.

ETHICS AND DISSEMINATION

This protocol has been approved by the Ethics Committee on Research with Humans of Hospital Sírio-Libanês (approval no. 24337707). Written informed consent will be obtained from each participant. The results of the study will be published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT03779126.

Effect of pulmonary rehabilitation on functional capacity in individuals treated for pulmonary tuberculosis: a systematic review protocol

OBJECTIVE

The aim of this review is to synthesize the available evidence on the effectiveness of pulmonary rehabilitation on the functional capacity of people who have finished drug treatment for pulmonary tuberculosis.

INTRODUCTION

Pulmonary rehabilitation is a treatment option for physical functional problems that persist after pharmacological treatment for tuberculosis; however, the results of primary studies on the subject are inconclusive.

INCLUSION CRITERIA

This review will consider for inclusion studies carried out with adults (≥18 years old) who have completed pharmacological treatment for tuberculosis. Outcomes of interest will include functional capacity, quality of life, lung function, respiratory and skeletal muscle strength, subjective perception exertion, and dyspnea.

METHODS

Searches for published and unpublished studies will be carried out on MEDLINE (via PubMed), LILACS, PEDro, CINAHL, Web of Science, Embase, Science Direct, Scopus, Cochrane Library (CENTRAL), Sport Medicine and Education Index, Rehabilitation and Sports Medicine Source, and SPORTDiscus. The results of the review will be reported according to PRISMA guidelines. There will be no language or time limitations. Two independent reviewers will select and critically appraise the selected studies and extract the data using standardized instruments. The certainty of evidence will be reported according to GRADE. Where appropriate, studies will be subjected to meta-analysis. Effect sizes will be expressed in odds ratios (for dichotomous data) or in standardized mean difference (for continuous data) and its 95% CI.

SYSTEMATIC REVIEW REGISTRATION NUMBER

PROSPERO CRD42021254719.

The Six-Minute Stepper Test Is Valid to Evaluate Functional Capacity in Hospitalized Patients With Exacerbated COPD

Background: The six-minute stepper test (6MST) is a self-paced test considered a valid tool to assess functional capacity in stable COPD patients. However, a high floor effect, where a large proportion of participants reach the minimum score when using the measurement instrument, might compromise the test validity in the hospital setting. Therefore, this study aimed at verifying the concurrent validity of 6MST in hospitalized patients with acute exacerbation of COPD (AECOPD).

Methods: A cross-sectional study was conducted in a tertiary hospital. Patients who were hospitalized due to AECOPD were considered for inclusion. On the first day, when patients reached minimum clinical criteria considered as the use of non-invasive ventilation less than 2 h for 6 h/period, dyspnea at rest less than 7 (very severe) on the modified Borg scale, a respiratory rate less than 25 breaths per minute, oxygen pulse saturation greater than 88% (considering use of supplemental oxygen) and absence of paradoxical breathing pattern, they underwent a lung function evaluation and answered three questionnaires: Chronic Respiratory Questionnaire (CRQ), Modified Medical Research Council Dyspnea Scale (MMRC), and COPD Assessment Test (CAT). Then, on two consecutive days, patients performed 6MST or six-minute walk test (6MWT), in random order. Each test was performed twice, and the best performance was recorded. Also, the patient’s severity was classified according to the BODE index. Inspiratory capacity measurements were performed before and after each test execution.

Results: Sixteen patients (69.4 ± 11.4 years) with a mean FEV₁ of 49.4 ± 9.9% predicted were included (9 females). There was a strong correlation of the performance in 6MST (number of cycles) with 6MWT (distance walked in meters) in absolute values (r = 0.87, p < 0.001) as well as with the percentage of predicted normal 6MWT (r = 0.86, p < 0.001). There was a strong correlation between the performance in 6MST with the dynamic hyperinflation (r = 0.72, p = 0.002) and a moderate correlation between 6MST with the percentage of reduction of inspiratory capacity (r = 0.68, p = 0.004). We also identified that 6MST showed moderate negative correlations with CAT (r = −0.62, p = 0.01) and BODE index (r = −0.59, p = 0.01).

Conclusion: It could be concluded that 6MST is valid for evaluating functional capacity in hospitalized patients with exacerbated COPD.

Validity and reliability of a new incremental step test for people with chronic obstructive pulmonary disease

BACKGROUND

Incremental step tests (IST) can be used to assess exercise capacity in people with chronic obstructive pulmonary disease (COPD). The development of a new step test based on the characteristics of the incremental shuttle walk test (ISWT) is an important study to explore. We aimed to develop a new IST based on the ISWT in people with COPD, and assess its validity (construct validity) and reliability, according to Consensus-based Standards for the selection of health status Measurement Instruments (COSMIN) recommendations.

METHODS

A cross-sectional study was conducted in participants recruited from hospitals/clinics. During the recruitment, the participants who presented a 6-minute walk test (6MWT) report in the previous month were also identified and the respective data was collected. Subsequently, participants attended two sessions at their homes. IST was conducted on the first visit, along with the 1 min sit-to-stand (1MSTS) test. IST was repeated on a second visit, performed 5-7 days after the first one. Spearman's correlations were used for construct validity, by comparing the IST with the 6MWT and the 1MSTS. Intraclass correlation coefficient (ICC_2,1), SE of measurement (SEM) and minimal detectable change at 95% CI (MDC95) were used for reliability. The learning effect was explored with the Wilcoxon signed-rank test.

RESULTS

50 participants (70.8±7.5 years) were enrolled. IST was significant and moderate correlated with the 6MWT (ρ=0.50, p=0.020), and with the 1MSTS (ρ=0.46, p=0.001). IST presented an ICC_2,1=0.96, SEM=10.1 (16.6%) and MDC95=27.9 (45.8%) for the number of steps. There was a statistically significant difference between the two attempts of the IST (p=0.030).

CONCLUSION

Despite the significant and moderate correlations with the 6MWT and 1MSTS, the inability to full compliance with the COSMIN recommendations does not yet allow the IST to be considered valid in people with COPD. On the other hand, the IST is a reliable test based on its high ICC, but a learning effect and an 'indeterminate' measurement error were shown.

TRIAL REGISTRATION NUMBER

NCT04715659.

Applicability of the step test for physical fitness assessment of women with chronic venous disease symptoms: a cross-sectional study

Abstract Background Chronic Venous Disease (CVD) can seriously impact physical fitness. Certain measures and aptitude tests can be employed to evaluate this condition in people with CVD that are simple, quick, and less expensive alternatives when compared to laboratory methods. Objectives To evaluate the applicability of the 4-minute step test, correlating its results with those of other measures and tests used with people with CVD symptoms. Methods Cross-sectional descriptive study carried out with 47 active women with CVD symptoms who participate in public physical exercise programs and were recruited by spontaneous demand. After clinical evaluation of disease stage, sociodemographic data were collected and calf circumference measurements, ankle goniometry, the tiptoe test, and the 4-minute step test were conducted. The women were already familiar with the apparatus used. Results The step test showed significant correlations (p<0.05) with calf measurements (r=0.31 and 0.32), flexibility (r=0.48 and 0.47), and the tiptoe test (r=0.33 for number of repetitions and 0.42 for speed of execution), in addition to an inverse correlation with disease severity (r=-0.29). Significant correlations were also found by age group (r=0.60 and 0.54, for calf circumference in the elderly) and by classification in tests and measurements (r=0.19 for the tiptoe test, and r=0 .29, for ankle flexibility). Conclusions The step test proved applicable and its use in conjunction with other aptitude tests offers a more complete evaluation of active women with CVD symptoms.

Aplicabilidade do teste do degrau na avaliação da aptidão física de mulheres com sintomas de doença venosa crônica: estudo transversal

Resumo Contexto A doença venosa crônica (DVC) pode impactar a aptidão física dos indivíduos. Algumas medidas e testes de aptidão são aplicados para avaliar essa condição em pessoas com DVC, sendo alternativas simples, rápidas e menos dispendiosas de avaliação comparadas a métodos laboratoriais. Objetivos Avaliar a aplicabilidade do teste do degrau de 4 minutos, correlacionando seus resultados com os de outras medidas e testes aplicados a pessoas com sintomas de DVC. Métodos Estudo descritivo transversal realizado com 47 mulheres ativas com sintomas de DVC, participantes de programas públicos de exercícios físicos e recrutadas por demanda espontânea. Foi realizada avaliação clínica da doença, e foram coletados dados sociodemográficos, medidas de perimetria de panturrilha e goniometria de tornozelo, teste ponta do pé e teste do degrau de 4 minutos. As mulheres já eram familiarizadas com o implemento utilizado. Resultados O teste do degrau apresentou correlações significativas (p < 0,05) com as medidas de panturrilha (r = 0,31 e 0,32), flexibilidade (r =0,48 e 0,47) e teste ponta do pé (r = 0,33 para n.º de repetições e 0,42 para velocidade de execução), além de correlação inversa com a gravidade da doença (r = -0,29). Correlações significativas também foram encontradas por faixa etária (r = 0,60 e 0,54, para perimetria de panturrilha em idosos) e por classificação nos testes e medidas (r = 0,19 para o teste ponta do pé e r = 0,29 para flexibilidade de tornozelo). Conclusões O teste do degrau se mostra aplicável, e sua utilização, em conjunto com outros testes de aptidão, permite uma avaliação mais completa de mulheres ativas com sintomas de DVC.

Six-month outcomes and effect of pulmonary rehabilitation among patients hospitalized with COVID-19: a retrospective cohort study

BACKGROUND

Patients appear to maintain sequelae post-coronavirus disease 2019 (COVID-19) affecting daily life and physical health. We investigated the changes in and the effects of pulmonary rehabilitation (PR) on exercise capacity and immunology six months after COVID-19 hospitalization.

METHODS

This retrospective cohort reviewed 233 COVID-19 patients admitted from 17 January 2020 to 29 February 2020. Ninety-eight patients who completed 2-week and 6-month follow-ups and tests were included. Among 98 patients, 27 completed at least five sessions of PR at the First Hospital of Changsha, China, during the 6-month convalescence were allocated to the PR group; the reminder who had not performed any PR were assigned to the control group. The primary outcome was the change in six-minute walk distance (6-MWD) between the 2-week and 6-month follow-ups, which was assessed via analysis of covariance with a covariate of propensity score that adjusted for the potential confounders. Secondary outcomes were the changes in 6-MWD, SARS-CoV-2 immunoglobulins, T-lymphocytes and blood chemistry, which were evaluated via paired tests.

RESULTS

Participants' ages ranged from 19 to 84 years (M = 47, standard deviation (SD)=15) 45.9% identified as male. During the 6-month convalescence, 6-MWD increased 27.0%, with a mean [95% CI] of 113 [92-134] m (p < .001). SARS-CoV-2 IgG and IgM decreased 33.3% (p = .002) and 43.8% (p = .009), CD4+ T cells increased 7.9% (p = .04), and the majority of blood chemistry significantly changed. The patients in the PR group acquired a greater increase in 6-MWD than those in control (unadjusted, 194 [167-221] m, p < .001; adjusted, 123 [68-181] m, p < .001), dose-responsiveness of PR on 6-MWD was observed (p < .001). No differences in immunity variables and blood chemistry were observed between groups.

CONCLUSIONS

These findings suggest PR may be a strategy to promote the improvement of exercise capacity after COVID-19.

Social Participation and Associated Factors in Individuals with Chronic Obstructive Pulmonary Disease on Long-Term Oxygen Therapy

Long-term oxygen therapy (LTOT) reduces hypoxaemia and mitigate systemic alterations in chronic obstructive pulmonary disease (COPD), however, it is related to inactivity and social isolation. Social participation and its related factors remain underexplored in individuals on LTOT. This study investigated social participation in individuals with COPD on LTOT and its association with dyspnoea, exercise capacity, muscle strength, symptoms of anxiety and depression, and quality of life. The Assessment of Life Habits (LIFE-H) assessed social participation. The modified Medical Research Council dyspnoea scale, the 6-Minute Step test (6MST) and handgrip dynamometry were used for assessments. In addition, participants responded to the Hospital Anxiety and Depression Scale (HADS) and the Chronic Respiratory Questionnaire (CRQ). Correlation coefficients and multivariate linear regression analyses were applied. Fifty-seven participants with moderate to very severe COPD on LTOT were included (71 ± 8 years, FEV₁: 40 ± 17%predicted). Social participation was associated with dyspnoea (r_s=-0.46, p < 0.01), exercise capacity (r = 0.32, p = 0.03) and muscle strength (r = 0.25, p = 0.05). Better participation was also associated with fewer depression symptoms (r_s=-0.40, p < 0.01) and a better quality of life (r = 0.32, p = 0.01). Dyspnoea was an independent predictor of social participation (p < 0.01) on regression models. Restricted social participation is associated with increased dyspnoea, reduced muscle strength and exercise capacity. Better participation is associated with fewer depression symptoms and better quality of life in individuals with COPD on LTOT.

Reliability and validity of six-minute step test in patients with heart failure

Exercise intolerance is the hallmark consequence of advanced chronic heart failure (HF). The six-minute step test (6MST) has been considered an option for the six-minute walk test because it is safe, inexpensive, and can be applied in small places. However, its reliability and concurrent validity has still not been investigated in participants with HF with reduced ejection fraction (HFrEF). Clinically stable HFrEF participants were included. Reliability and error measurement were calculated by comparing the first with the second 6MST result. Forty-eight hours after participants underwent the 6MST, they were invited to perform a cardiopulmonary exercise test (CPET) on a cycle ergometer. Concurrent validity was assessed by correlation between number of steps and peak oxygen uptake (V̇O₂ peak) at CPET. Twenty-seven participants with HFrEF (60±8 years old and left ventricle ejection fraction of 41±6%) undertook a mean of 94±30 steps in the 6MST. Intra-rater reliability was excellent for 6MST (ICC=0.9), with mean error of 4.85 steps and superior and inferior limits of agreement of 30.6 and -20.9 steps, respectively. In addition, strong correlations between number of steps and CPET workload (r=0.76, P<0.01) and peak V̇O₂ (r=0.71, P<0.01) were observed. From simple linear regression the following predictive equations were obtained with 6MST results: V̇O₂ peak (mL/min) = 350.22 + (7.333 × number of steps), with R²=0.51, and peak workload (W) = 4.044 + (0.772 × number of steps), with R²=0.58. The 6MST was a reliable and valid tool to assess functional capacity in HFrEF participants and may moderately predict peak workload and oxygen uptake of a CPET.

Individualized, low-cost and accessible pulmonary rehabilitation program based on functional clinical tests for individuals with COPD-a study protocol of a randomized controlled trial

BACKGROUND

Patients with chronic obstructive pulmonary disease (COPD) present pulmonary and extrapulmonary impairments. The strategies used to mitigate these impairments are pulmonary rehabilitation programs (PRP). However, there is limited access to PRP in specialized centers and the study of low-cost home rehabilitation programs had non-individualized prescription, which might have led to insignificant positive effects. So, it is important to develop new low-cost protocols that involve individualized prescription, as well as physiotherapist supervision. This study describes an accessible, low-cost, and individualized pulmonary rehabilitation protocol and compare its results when performed with or without a weekly physiotherapist-supervised session on patients with COPD.

METHODS

This is a descriptive protocol of a clinical trial, randomized, single-blinded, and type of framework is superiority conducted at the Spirometry and Respiratory Physical Therapy Laboratory of the Federal University of São Carlos (UFSCar). The trial is registered in the Brazilian Clinical Trials Registry (ReBec) URL: http://www.ensaiosclinicos.gov.br/rg/RBR-533hht/ with Register Number UTN code U1111-1220-8245. The sample size is 50 patients and is calculated using the results of a pilot study.

DISCUSSION-POTENTIAL IMPACT AND SIGNIFICANCE OF THE STUDY

It is expected that the low-cost and new supervised rehabilitation program complemented with home exercises will present positive results, especially on exercise capacity, which will make available a more accessible and effective PRP for patients with COPD.

TRIAL REGISTRATION

ClinicalTrials.gov U1111-1220-8245 . Registered on September 20, 2018.

Low-Frequency Vibration Facilitates Post-Exercise Cardiovascular Autonomic Recovery

It is important to use short breaks to accelerate post-exercise recovery in sports. Previous studies have revealed that vibration can reduce post-exercise muscle soreness. However, there is still high heterogeneity in the effects of vibration on cardiovascular autonomic activities, and most studies to date have focused on high-frequency vibration. This study aimed to investigate the effect of low-frequency lower-body vibration (LBV) on post-exercise changes in heart rate variability and peripheral arterial tone. Ten men and 9 women aged 20 to 25 were recruited for this study. Each subject visited the testing room three times with at least 2 days in between. Each time, the subject received one of the three different vibration frequencies (0, 5, and 15 Hz) in a random order in the sitting position for 10 minutes. LBV was performed immediately after a static standing (control) test and 3-min-step test. Heart rate variability and digital volume pulse wave were recorded during the vibration phase (V1: vibration 0-5 minutes; V2: 6-10 minutes) and the recovery phase (Rc1: recovery phase 11-15 minutes; Rc2: 16-20 minutes). The result of digital pulse wave analysis showed that the reflection index (RI) under 15 Hz decreased during V1. Heart rate of the 15-Hz group also decreased during Rc1 and Rc2. According to the analysis of heart rate variability, low-frequency power/high-frequency power (LF/HF) decreased and normalized high-frequency power (nHF) increased during V2, Rc1 and Rc2 under 15 Hz and, during Rc2 under 5 Hz vibration. This study confirmed that the application of low-frequency LBV after exercise can reduce peripheral vascular tone, accelerate heart rate recovery, decrease cardiac sympathetic nerve activity, and promote parasympathetic nerve activity. The effect was more pronounced at 15 Hz than at 5 Hz. The findings provide a method to accelerate cardiovascular autonomic recovery after exercise.

The Six-Minute Step Test as a Predictor of Functional Capacity according to Peak VO2 in Cardiac Patients

BACKGROUND

Six-minute step test (6MST) is a simple way to evaluate functional capacity, although it has not been well studied in patients with coronary artery disease (CAD) or heart failure (HF).

OBJECTIVE

Analyze the association between the 6MST and peak oxygen uptake (VO2peak) and develop an equation for estimating VO2peak based on the 6MST, as well as to determine a cutoff point for the 6MST that predicts a VO2peak ≥20 mL.Kg-1.min-1.

METHODS

In 171 patients who underwent the 6MST and a cardiopulmonary exercise test, correlation, regression, and ROC analysis were used and a p < 0.05 was admitted as significant.

RESULTS

mean age was 60±14 years and 74% were male. Mean left ventricle ejection fraction was 57±16%, 74% had CAD and 28% had HF. Mean VO2peak was 19±6 mL.Kg-1.min-1 and mean 6MST performance was 87±45 steps. Association between 6MST and VO2peak was r 0.69 (p <0.001). The model VO2peak =19.6 + (0.075 x 6MST) - (0.10 x age) for men and VO2peak =19.6 + (0.075 x 6MST) - (0.10 x age) - 2 for women could predict VO2peak based on 6MST results (adjusted R 0.72; adjusted R2 0.53). The most accurate cutoff point for 6MST to predict a VO2peak ≥20 mL.Kg-1.min-1 was >105 steps (AUC 0.85; 95% CI 0.79 -0.90; p <0.001).

CONCLUSION

An equation for predicting VO2peak based on 6MST results was derived, and a significant association was found between 6MST and VO2peak. The cutoff point for 6MST, which predicts a VO2peak ≥20 mL.Kg-1.min-1, was >105 steps. (Arq Bras Cardiol. 2021; 116(5):889-895).

[Which physical tests for which objectives in pulmonary rehabilitation?]

Chronic respiratory disease is a major cause of morbidity and mortality worldwide and an important cause of disability including a reduction of exercise, functional and muscle capacity contributing to a decreased quality of life. In the context of pulmonary rehabilitation, a thorough patient-centered outcome assessment, including not only measures of lung function, but also exercise functional and muscle capacity, is imperative for a comprehensive disease management. Assessment of these impairments and dysfunctions with appropriate and change-sensitive procedures is thus necessary for personalizing the physical interventions and assessing the short- and long-term effectiveness of the intervention. The clinician currently has a wide variety of tests and measurements available to assess the physical and functional capacity of people with chronic respiratory disease. The aim of this review is to provide a pragmatic synthesis of the physical, functional and muscle capacity tests most commonly used in pulmonary rehabilitation. Ultimately, it should help the clinician to identify the relevant evaluations according to the objectives of the patients but also according to the available resources, the setting of pulmonary rehabilitation and the specific qualities of each test.

Slow chest compression acutely reduces dynamic hyperinflation in people with chronic obstructive pulmonary disease: a randomized cross-over trial

Background: Strategies to minimize dynamic hyperinflation (DH) and dyspnea, such as slow chest compression (SCC), are relevant in people with chronic obstructive pulmonary disease (COPD).Objectives: To analyze the acute effects of SCC after exercise on DH and dyspnea in people with COPD and to identify responders to the technique.Methods: This is a cross-over study with 40 patients. Two six-minute step tests (6MSTs) were performed followed by a one-minute application of SCC (6MST_SCC) or rest (6MST_CONTROL), at random. End-expiratory lung volume (EELV) and dyspnea were assessed. A difference ≥76 ml in ΔEELV between SCC and control characterized the responders.Results: The performance in 6MST_SCC and 6MST_CONTROL were similar. There was a greater reduction in EELV after 6MST_SCC compared to 6MST_CONTROL (124 ± 193 ml vs. 174 ± 183 ml; p = .049), while there was no difference in change in dyspnea between the SCC and control groups. Twenty-one participants were SCC responders and had higher functional residual capacity [FRC: 5.36 ± 1.09 vs. 4.58 ± 0.94; p = .02; cutoff point: 4.56; sensitivity = 76%; specificity = 53%; AUC = 0.71 (95%CI: 0.54 to 0.87); p = .02].Conclusion: SCC applied immediately after exercise reduced DH, but did not reduce dyspnea in people with COPD. The technique is beneficial only for some patients and FRC can help to identify them.

Relationship of phase angle and peak torque of knee extensors with the performance in six-minute step test in haemodialysis patients

BACKGROUND

Chronic kidney disease is a systemic disease affecting not only renal function, but also endocrine, cardiovascular, and skeletal muscle systems, with broad impact on functionality. Therefore, the assessment of body composition, peripheral muscle function, and exercise tolerance is also of great importance in this population. In addition, the development of reliable strategies that use feasible tools in clinical practice is of great importance in the functional diagnosis, clinical management and prescription of physical activity.

OBJECTIVE

To assess the relationship between phase angle and peak torque of knee extensors with the performance in six-minute step test of patients with chronic kidney disease undergoing haemodialysis.

METHODS

Observational and cross-sectional study at Haemodialysis Centre of Sírio-Libanês Hospital. The evaluations took place 3 days before the haemodialysis sessions. On the first day, patients underwent anthropometric evaluation and biochemical tests (lactate, urea, creatinine, albumin, ferritin and growth factor similar to insulin type 1 [IGF1]). On the second day, performed electrical bioimpedance and exercise tolerance assessed using the six-minute step test. On the last day, the evaluation of knee extensor muscles strength using isokinetic dynamometry was performed.

RESULTS

Eighteen subjects were included, with a mean age of 62.3 ± 17.6 years. A positive linear correlation was observed between the phase angle, derived from the electrical bioimpedance, and the performance in six-minute step test in these patients. It was also possible to observe a linear correlation between phase angle and IGF1, handgrip strength, peak torque of knee extensors and quality of life questionnaire. The peak torque of knee extensors also presented a linear correlation with IGF1, the performance in six-minute step test and mal-nutrition and inflammation score.

CONCLUSION

Phase angle and peak torque of knee extensors were correlated with the performance in six-minute step test. Therefore, the phase angle seems to be an important marker of reduced peripheral muscle function and exercise tolerance in haemodialysis patients.

Reproducibility of the 6-Min Step Test in Subjects With COPD

BACKGROUND

Test-retest reproducibility of the 6-min step test (6MST) is controversial in patients with COPD because the decision to perform a second test is influenced by interruptions, physiological overload, and the patient's exercise tolerance. The aim of this study was to analyze the reproducibility of performance on the 6MST (ie, number of steps climbed and interruptions) and physiological variables in subjects with COPD, with and without poor exercise tolerance, and with and without interruptions during the test.

METHODS

Subjects performed 2 6MST (6MST₁, 6MST₂) with a minimum of 30 min rest between tests. Physiological variables were assessed with a gas analyzer. Subjects who performed ≤ 78 steps in the 6MST₁ and ≤ 86 steps in the test with the higher number of steps performed (6MST_BEST) were considered to have poor exercise tolerance. Subjects were also stratified according to those who interrupted the 6MST_BEST and those who did not interrupt the 6MST_BEST.

RESULTS

40 subjects (31 men; FEV₁ percent of predicted = 50.4 ± 13.5) participated in the study. The number of steps, interruptions, and physiological variables showed moderate to high reliability (intraclass correlation coefficient: 0.70-0.99, P < .001). Thirty-one (77.5%) subjects had a better performance during 6MST₂ than 6MST₁ (mean difference: 4.65 ± 5.59, P < .001). Although the number of times subjects were interrupted was similar between the 2 tests (P = .66), the duration of these interruptions was shorter during 6MST₂ (mean difference: -0.12 ± 0.39 s, P = .040). The difference in the number of steps (6MST₂ - 6MST₁) did not differ between subjects who performed ≤78 steps (mean difference: 5.64 ± 5.32 steps; 10.3%; P < 0.001) and ≥ 79 steps (3.00 ± 5.82 steps; 6.13%; P = 0.08) on the 6MST₁ (P = 0.15) and between subjects who performed ≤ 86 steps (5.39 ± 5.14 steps; 9.39%; P < 0.001) and ≥ 87 steps (2.92 ± 6.43 steps; 2.74%; P = 0.14) steps on the 6MST_BEST (P = 0.20).

CONCLUSIONS

Performance and physiological variables in the 6MST were reproducible, and a second test did not impose greater physiological overload. Two tests were essential for patients with poor exercise tolerance.

The five-repetition sit-to-stand test is a predictive factor of severe exacerbations in COPD

Background:

Although the six-minute-walk test (6MWT) has been used to predict chronic obstructive pulmonary disease (COPD) exacerbations, additional research is necessary to identify more rapid, simpler tests that are directly associated with exacerbations, such as the five-repetition sit-to-stand (5STS) test and 4-m gait speed (4MGS) test.

Aims:

To determine the ability of the 5STS and 4MGS tests in predicting severe exacerbations in stable COPD over the following year, and to assess the ability of the best prognostic test to identify patients at high risk of hospital admission correctly.

Methods:

This prospective study included 137 patients with stable COPD. Multiple logistic regression models were constructed to assess whether the 6MWT, 5STS, and 4MGS tests were associated with severe exacerbations in the year following the test. Receiver-operating characteristic curves and the area under the curve (AUC) were evaluated to determine the accuracy of each test for identifying patients with severe exacerbations.

Results:

Scores of <350 m for the 6WMT and ⩽2 for the 5STS test were associated with severe exacerbations in the model adjusted for age and the number of exacerbations in the previous year. The 5STS test and the 6MWT had very similar predictive and discriminative abilities. Odds ratios were 3.20 (95% confidence interval [CI] 1.14–8.96) and 3.84 (95% CI 1.14–12.94) and AUCs were 0.793 (95% CI 0.704–0.882) and 0.783 (95% CI 0.686–0.879), respectively.

Conclusions:

The 5STS test predicted the risk of severe exacerbation within the following year among patients with COPD. The 5STS test could replace the 6MWT for identifying patients at high risk of hospital admission.

Testes funcionais validados em indivíduos hospitalizados e não hospitalizados: revisão sistemática

Objetivo: Realizar uma revisão sistemática sobre os testes funcionais validados em diferentes perfis de indivíduos hospitalizados e não hospitalizados e avaliar as evidências psicométricas para confiabilidade e validade. Métodos: Trata-se de uma revisão sistemática. Foram utilizadas as bases de dados EMBASE, MEDLINE, Lilacs e SciELO com as palavras-chave Functional Tests (Walk Test, Gait Speed Test, Chair Stand Test, Timed Up And Go, Step Test),Validation Studies as Topic e sinônimos. Foram incluídos estudos de validação de testes funcionais em indivíduos hospitalizados ou não hospitalizados que utilizaram os critérios de validade e/ou confiabilidade e relacionaram os testes a diferentes variáveis. Esses artigos poderiam ser observacionais longitudinais ou de corte transversal ou estudos de validação que utilizaram dados de ensaios clínicos. Foram excluídos os artigos que não apresentaram características importantes da amostra e a descrição do teste. Resultados: A pesquisa resultou em 36.150 artigos, e 89 foram incluídos. Os estudos foram organizados em tabelas com informações como autor, ano; critérios de validação; amostra; teste; variáveis associadas; resultados. A qualidade dos artigos foi avaliada por meio da Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. Conclusão: Os testes funcionais são válidos e confiáveis para a avaliação de indivíduos hospitalizados e não hospitalizados, estando associados à força muscular, capacidade de caminhar, controle postural, atividades de vida diária, risco de quedas, hospitalização e mortalidade.

Exacerbated hemodynamic response during exercise in cancer patients prior to autologous hematopoietic stem cell transplantation

PURPOSE

Chemotherapy treatment can lead to cardiovascular toxicity and physical impairment prior to autologous hematopoietic stem cell transplantation (auto-HSCT). Cardiovascular adjustments during exercise and the exercise capacity remain unknown in patients prior to auto-HSCT. Thus, the hemodynamic responses during exercise and exercise capacity were evaluated using a novel effort test in patients prior to auto-HSCT.

METHODS

Thirty patients prior to auto-HSCT (BMT group: 44.6 ± 14.1 years) and 23 control participants (CON group: 43.9 ± 16.6 years) performed the 6-Minute Step Test (6MST) to assess their exercise capacity and the hemodynamic responses during exercise. Systolic and diastolic blood pressure (SBP and DBP), heart rate (HR), and oxygen saturation (SpO₂) were measured during the test. Rate-pressure product (RPP) was calculated multiplying SBP by HR. The highest HR value recorded during the test was compared with the maximum HR predicted by age and was used as % of maximum HR (%HRmax).

RESULTS

The number of steps up and down performed by the BMT group was lower than CON (108.8 ± 25.3 vs. 127.5 ± 34.4 steps, P = 0.02). The BMT group showed a higher magnitude of increase in SBP and RPP during the 6MST when compared to CON (ΔSBP: 18.5 ± 11.45 vs. 8.30 ± 18.46 mmHg, P = 0.01; and ΔRPP: 8197.3 ± 3829.1 vs. 6170.9 ± 3568.9 mmHg beats min^-1, P = 0.05). The BMT group exhibited higher SpO2 and HR values throughout the protocol (P < 0.05), reaching a higher %HRmax than CON group (76.9 ± 9.6 vs. 66.4 ± 8.9%, P < 0.01).

CONCLUSIONS

Patients with indication for auto-HSCT have exacerbated chronotropic and pressor responses during exercise and reduced exercise capacity in the 6MST.

Measurement properties of step tests for exercise capacity in COPD: A systematic review

Objective:

To determine the level of evidence of the measurement properties (validity, reliability, and responsiveness) and interpretability of the step tests available for assessing the exercise capacity in patients with chronic obstructive pulmonary disease.

Data sources:

The data sources Web of Science, MEDLINE, PubMed, PEDro, CENTRAL of Cochrane Library, and Scopus were searched up to June 26, 2020.

Review methods:

Studies of any design that reported results for any measurement property of the step tests for assessing the exercise capacity in COPD patients were selected. One reviewer extracted the data, and two reviewers independently rated the level of evidence by using the Consensus-Based Standards for the Selection of Health Measurements Instruments recommendations.

Results:

Thirty-one studies were included in the data synthesis. Chester Step Test, Modified Incremental Step Test, two-, three-, four-, and six-Minute Step Test, Paced Step Test, and six-Minute Stepper Test were identified. A step test protocol was also found. The level of evidence of their results for the measurement properties was mostly determined as “low” to “very low.” The best level of evidence found was for the six-minute stepper test: “high” on construct validity (r = 0.56–0.71); and “moderate” on criterion validity (r = 0.36–0.69), and responsiveness (r = 0.26–0.34).

Conclusion:

The general level of evidence of the measurement properties of the step tests is “low” to “very low” for assessing exercise capacity in patients with chronic obstructive pulmonary disease, which can limit their application in clinical practice. The six-minute Stepper Test is currently the most appropriate step test available.

Home-based or remote exercise testing in chronic respiratory disease, during the COVID-19 pandemic and beyond: A rapid review

Objectives:

To identify exercise tests that are suitable for home-based or remote administration in people with chronic lung disease.

Methods:

Rapid review of studies that reported home-based or remote administration of an exercise test in people with chronic lung disease, and studies reporting their clinimetric (measurement) properties.

Results:

84 studies were included. Tests used at home were the 6-minute walk test (6MWT, two studies), sit-to-stand tests (STS, five studies), Timed Up and Go (TUG, 4 studies) and step tests (two studies). Exercise tests administered remotely were the 6MWT (two studies) and step test (one study). Compared to centre-based testing the 6MWT distance was similar when performed outdoors but shorter when performed at home (two studies). The STS, TUG and step tests were feasible, reliable (intra-class correlation coefficients >0.80), valid (concurrent and known groups validity) and moderately responsive to pulmonary rehabilitation (medium effect sizes). These tests elicited less desaturation than the 6MWT, and validated methods to prescribe exercise were not reported.

Discussion:

The STS, step and TUG tests can be performed at home, but do not accurately document desaturation with walking or allow exercise prescription. Patients at risk of desaturation should be prioritised for centre-based exercise testing when this is available.

Impaired performance of women with patellofemoral pain during functional tests

OBJECTIVE

To compare the performance, reliability, and validity of functional tests between women with and without patellofemoral pain.

METHODS

Twenty women with a diagnosis of patellofemoral pain between 18 and 40 years of age and 20 age-matched pain-free controls participated in the study. All participants performed a set of five function tests: sitting-rising test, sit-to-stand in 30 seconds, stair-climb test, stair descent test, and six-minute step test. To investigate reliability, participants were assessed on two different days, seven days apart, by two independent investigators blinded to the results of the other investigator. Validity was evaluated through associations with the results on the Anterior Knee Pain Scale.

RESULTS

Performance in the tests was worse in women with patellofemoral pain than in the control group for the sit-to-stand in 30 seconds (mean difference [MD] 3.4reps; 95%CI: 0.4, 6.4), stair-climb test (MD: 0.36s; 95%CI: 0.1, 0.63), and six-minute step test (MD: 45reps; 95%CI: 20, 70). No differences were observed for the sitting-rising and stair descent tests. All tests in both groups showed moderate to excellent intra- and inter-rater reliability (intraclass correlation coefficients: 0.61 to 0.91 and 0.72 to 0.96, respectively). Finally, only the results on the sit-to-stand in 30 seconds test correlated with the Anterior Knee Pain Scale (r=0.44, p=0.047) in the patellofemoral pain group.

CONCLUSION

Women with patellofemoral pain present lower performance on some functional tests. Functional tests are reliable in patients with patellofemoral pain, although they are not associated with the results on the Anterior Knee Pain Scale self-questionnaire.

Supervised exercise protocol for lower limbs in subjects with chronic venous disease: an evaluator-blinded, randomized clinical trial

Background

Chronic venous insufficiency (CVI) causes pathophysiological changes in the lower-limb muscles, particularly the calf muscles, and limits ankle range of motion (ROM). These changes reduce functional activities and decrease quality of life (QOL). Although several studies have shown the benefits of exercise (strengthening the calf muscles to improve calf-muscle pumping and QOL) in patients with CVI, few studies are randomized controlled trials. This has led to a weak indication of exercise for the treatment of patients with CVI. The aim of this study is to analyze the effects of a supervised exercise program to improve calf-muscle endurance as well as QOL in patients with CVI.

Methods/design

This is an evaluator-blind, randomized clinical trial with an 8-week duration and a follow-up evaluation at week 16. A pilot study with subjects with a CVI diagnosis will be performed to calculate sample size. The participants will be randomly allocated (1:1) into a treatment or a control group (usual care/no intervention). The treatment intervention consists of a bi-weekly supervised exercise program of the lower limbs that will include aerobic training, strengthening and cardiovascular exercises. The participants from both groups will participate in a health education lecture. Primary outcomes are changes in calf-muscle endurance and QOL score. Secondary outcomes are changes in exercise capacity, ankle ROM, electrical muscle activity and cardiac output. The first statistical comparison will be performed after 8 weeks’ intervention.

Discussion

Patients with CVI may have an impaired calf-muscle pump and decreased exercise capacity. A randomized controlled trial evaluating a supervised exercise program should provide much needed information on the management of CVI to promote health and independence.

Trial registration

This study was registered on the Brazilian Clinical Trials Database (REBEC) (RBR-57xtk7). The results will be disseminated at scientific events, presentations, and publications in peer-reviewed journals.

Construct validity and reproducibility of the six-minute step test in subjects with obstructive sleep apnea treated with continuous positive airway pressure

OBJECTIVE

To evaluate the construct validity and reproducibility of the six-minute step test (6MST) in individuals with obstructive sleep apnea (OSA) treated with continuous positive airway pressure (CPAP).

METHODS

We evaluated 48 volunteers diagnosed with OSA and treated with CPAP for at least two months. The volunteers underwent the six-minute walk test (6MWT) and the 6MST, in random order and on different days, with an interval of, at most, seven days between the two tests.

RESULTS

A moderate positive correlation was found between the distance walked on the 6MWT and the number of steps climbed on the 6MST (r = 0.520; p < 0.001). There was no significant difference between the two 6MSTs in terms of the number of steps climbed (121.7 ± 27.1 vs. 123.6 ± 26.7). Reproducibility for performance on the 6MST and for cardiovascular variables was considered excellent (intraclass correlation coefficient > 0.8). Regarding cardiovascular responses, the 6MST produced higher values than did the 6MWT for HR at six minutes, percent predicted maximum HR, and leg fatigue at six minutes, as well as for systolic blood pressure at six minutes and at one minute of recovery.

CONCLUSIONS

The 6MST is valid and reproducible, producing greater cardiovascular stress than does the 6MWT. However, the 6MST is also characterized as a submaximal test for the assessment of exercise tolerance in individuals with OSA treated with CPAP.

Effectiveness and Safety of Supervised Home-Based Physical Training in Patients With COPD on Long-term Home Oxygen Therapy: A Randomized Trial

BACKGROUND

Patients with COPD in advanced stages who need long-term home oxygen therapy (LTHOT) have difficulty participating in outpatient pulmonary rehabilitation (PR) programs. This difficulty is due to the severity of their disease, limitations involving transportation and mobility, high costs, and issues related to patients' safety and individual needs. Unsupervised home-based physical training (PT) is frequently used.

RESEARCH QUESTION

The main objective of this study was to investigate the effectiveness of a supervised home-based PT program on exercise capacity and other outcomes in patients with COPD receiving LTHOT.

STUDY DESIGN AND METHODS

In a randomized clinical trial, patients with COPD who were on LTHOT were allocated into two groups: the supervised physical training (PT) group, consisting of patients who received home-based supervised muscle strength and endurance training in twice-weekly 60-min sessions for 12 weeks; and the unsupervised activity booklet group, consisting of patients who received a booklet advising them to perform exercise twice a week for 12 weeks. All participants were assessed prior to and following the intervention in terms of exercise capacity (6-min step-test and the 1-min sit-to-stand test); dyspnea (Medical Research Council scale); fatigue (Brazilian Portuguese version of the Fatigue Severity Scale); and health status (COPD Assessment Test).

RESULTS

A total of 44 patients were assessed (mean age, 70 ± 8 years; FEV₁, 33 ± 14% predicted) (PT group, n = 22; booklet group, n = 22). Only the PT group patients presented significant improvement in the 6-min step-test (21 ± 9 vs 14 ± 11; P = .001), Medical Research Council scale (3.3 ± 1.0 vs 3.9 ± 0.9; P = .013), Brazilian Portuguese version of the Fatigue Severity Scale (5.0 ± 1.4 vs 5.2 ± 1.3; P = .015), and COPD Assessment Test (21 ± 8 vs 26 ± 6; P = .001). No adverse effects were observed.

INTERPRETATION

Supervised home-based PT was effective and safe in improving exercise capacity, dyspnea, fatigue, and health status in patients with COPD on LTHOT.

CLINICAL TRIAL REGISTRATION

Brazilian Registry of Clinical Trials; No.: RBR-535smn; URL: http://www.ensaiosclinicos.gov.br.

Functional Capacity Change Impacts the Quality of Life of Hospitalized Patients Undergoing Hematopoietic Stem Cell Transplantation

OBJECTIVE

The aim of the study was to compare the quality of life (QOL) of patients undergoing hematopoietic stem cell transplantation who improved their functional capacity during hospitalization (increased functional capacity group) with that of patients who maintained or decreased functional capacity during hospitalization (decreased functional capacity group).

DESIGN

This observational, longitudinal study included 27 hospitalized patients undergoing hematopoietic stem cell transplantation. Patients were divided into increased functional capacity group (16 patients) and decreased functional capacity group (11 patients). Functional capacity (6-min step test), peripheral muscle strength (sit-to-stand test and handgrip strength), and QOL (European Organization for Research and Treatment of Cancer) were assessed at admission and at hospital discharge.

RESULTS

Increased functional capacity patients had increased functional capacity and peripheral muscle strength of the lower and upper limbs at hospital discharge (P < 0.01, <0.01, and 0.02, respectively). The patients in the increased functional capacity group demonstrated an increase in global health and reduced symptoms at discharge (P = 0.02 and 0.03, respectively). No significant differences were observed between groups in the functional domain.

CONCLUSIONS

Patients undergoing hematopoietic stem cell transplantation, who have improved functional capacity at discharge, also experience an improved QOL, with no such improvement noted among patients who have stable or reduced functional capacity. We recommend that the treatment protocol for hospitalized patients undergoing hematopoietic stem cell transplantation include an exercise program aimed at improving functional capacity.

Validity and reliability of the 6-min step test in individuals with coronary artery disease

OBJECTIVE

To assess the validity and reliability of the 6-min step test (6MST) in individuals with coronary artery disease (CAD).

METHODS

In a randomized and crossover design, 35 patients with CAD (65.8 ± 9.6 years), referred by a physician of a cardiology ambulatory, performed two 6MSTs and two 6-min walk tests (6MWTs) in order to assess reliability in patients with arterial coronary disease. The order of performance of the tests was established by a draw.

RESULTS

6MST test-retest reliability was excellent (intraclass correlation coefficient = 0.967; 95% CI: 0.766, 0.989; p < .05). There was an increase of 7.9 ± 8.2 steps from the first to the second 6MST, with a technical error of measurement = 8.0; p < .001. The correlations between distance walked in the 6MWT and number of steps in the 6MST in the first and second tests were 0.6 and 0.7 (p < .001), respectively.

CONCLUSION

The 6MST is a reliable test to measure functional capacity in individuals with CAD. The test is valid when using 6MWT as the gold standard. There is an 88% chance of a subject classified in a given tertile by the 6MWT being in the same tertile in the 6MST.

Validation of the two-minute step test in obese with comorbibities and morbidly obese patients

Cardiopulmonary fitness assessment is a valuable resource to obtain quantitative indicators of an individual's physical performance. The cardiopulmonary exercise test (CPX), considered the gold standard test for this evaluation, is costly and difficult to be accessed by the general population. In order to make this evaluation more accessible, and to better reflect the performance of daily life activities, alternative tests were proposed. Morbidly obese patients present limitations that impair physical performance assessment and could benefit from a test of shorter duration, provided it is validated. This observational study aimed to validate the two-minute step test (2MST) as a tool to evaluate functional capacity (FC) in obese with comorbidities and morbidly obese patients, compared the 2MST with CPX as a measure of physical performance, and developed a predictive equation to estimate peak oxygen uptake (VO₂) in the 2MST. The CPX and the 2MST were performed and metabolic and ventilatory parameters were recorded in 31 obese individuals (BMI>35 kg/m²). Pearson correlation and multiple linear regression analyses were performed to evaluate the peak VO₂ best predictors. Bland-Altman analysis was performed to assess the agreement between the two methods. Peak VO₂ measured by CPX and 2MST showed a strong correlation (r=0.70, P<0.001) and there was a moderate correlation between peak VO₂ of the 2MST and the number of up-and-down step cycles (UDS) (r=0.55; P=0.01). The reference equation obtained was: VO₂ (mL·kg^-1·min^-1) = 13.341 + 0.138 × total UDS – (0.183 × BMI), with an estimated standard error of 1.3 mL·kg^-1·min^-1. The 2MST is a viable, practical, and easily accessible test for FC. UDS and BMI can predict peak VO₂ satisfactorily.

Individualized in-hospital exercise training program for people undergoing hematopoietic stem cell transplantation: a feasibility study

PURPOSE

The purpose of this study is to evaluate the feasibility of an individualized exercise program for people undergoing hematopoietic stem cell transplantation.

METHODS

This is a feasibility study of an individualized in-hospital exercise training program for people undergoing hematopoietic stem cell transplantation. Participants performed the exercise program based on daily clinical, hemodynamic and hematological assessment. The program was carried out on a daily basis for 20-40 min during their hospital admission. The primary outcome was feasibility (recruitment, adherence and attrition rates) of the exercise program. The secondary outcomes were functional capacity, peripheral muscle strength, and health-related quality of life evaluated on admission and prior to hospital discharge. The adverse events rate was recorded during the intervention.

RESULTS

Twenty-six participants (58% female), aged 40 ± 15 (mean ± SD) years were included. The exercise program feasibility was demonstrated by 100% recruitment, 86% exercise adherence and 12% attrition rates with no adverse events recorded. Significant differences were observed in functional capacity (p = 0.03), upper and lower-limb muscle strength (p = 0.01) from admission to discharge (23 ± 7 d).

CONCLUSIONS

An individualized exercise training program based on daily clinical parameters is feasible for hospitalized patients undergoing hematopoietic stem cell transplantation. This intervention warrants further investigation in a randomized controlled trial. Implications for rehabilitation The individualized in-hospital exercise training program guided by daily clinical, hemodynamic and hematologic parameters is feasible, safe and with good adherence in people undergoing hematopoietic stem cell transplantation. People undergoing hematopoietic stem cell transplantation may improve functional capacity and upper and lower limb muscle strength following in-hospital exercise training program. The individualized in-hospital exercise training program could tentatively be introduced as part of the rehabilitation process in people undergoing hematopoietic stem cell transplantation.

Exercise Capacity and Respiratory Profile in Patients after Orthopedic Liver Transplantation: a Follow-up Study

INTRODUCTION

We sought to describe: 1) The influence of orthotopic liver transplantation (OLT) on exercise capacity, pulmonary function and respiratory muscle strength after surgery, 2) The relationship between exercise capacity and symptoms of anxiety and depression.

MATERIAL AND METHODS

This is a prospective follow up study conducted with patients submitted to OLT. All patients were assessed before and 1 month after surgery through measurements: six minute walk test (6MWT), 6 min step test (6MST) and HADS (Hospital Anxiety and Depression Scale). FEV1% (forced expiratory volume), maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) were measured in the pre-operative and on 1st, 3rd, 5th day and 1 month after surgery.

RESULTS

In 77 patients , 6MWD improved 20.2 m (95%CI 8.1-32.3) and 6MST improved 7.8 steps after surgery (95%CI 3.9-11.6). Change in 6 MWD and 6 MST did not correlated with change HADS. The FEV1% at each time point were 88.8 ± 21.3 before surgery, 32.9 ± 9.9 on 1st day, 39.6 ± 11.5 on 3rd day, 46 ± 12.1 on 5th day and 86.6 ± 21.1 one month after surgery. MIP and MEP values at each time point were -67.4 ± 23.2 and 79.7 ± 26 before surgery, -30.8 ± 12.3 and 36.4 ± 15.4 on 1st day, -38.6 ± 14.1 and 43.8 ± 17 on 3rd day, -45.8 ± 15.9 and 49.7 ± 18.7 on 5th day and -67.1 ± 29.4 and 80.9 ± 23.9 one month after surgery.

CONCLUSION

Exercise capacity was modestly increased after OLT without any correlation with symptoms of anxiety and depression. Pulmonary function and respiratory muscle strength decreased immediately after liver transplantation, and progressively recovered, returning to baseline values after 1 month.

Reversal Effect of Oxypeucedanin on P-glycoprotein-mediated Drug Transport

P-glycoprotein affects the transport of numerous drugs including chemotherapeutic drugs vincristine sulfate (VCR) and docetaxel (DTX), and is one of the main causes for multidrug resistance. Our previous studies have shown that oxypeucedanin (OPD) can enhance the intestinal transit of puerarin and VCR. However, the underlying mechanism is unclear. This study investigated the potential mechanism by which OPD improves P-gp-mediated drug transport. Molecular docking was performed to predict the binding force between OPD and P-gp and the contribution of OPD on P-gp activity. We observed the effect of OPD on the transport of VCR in MDCK-MDR1 cell monolayer and also measured the plasma pharmacokinetic parameters of DTX in the presence and absence of OPD by LC-MS/MS. Moreover, we further investigated the reversal mechanism of OPD on P-gp-mediated drug transport by determining the intracellular accumulation of Rhodamine-123 (Rh123) and P-gp ATPase activity as well as protein expression and mRNA level of P-gp. Our molecular docking results revealed that the binding force between OPD and P-gp was much lower than that between P-gp and verapamil (a P-gp substrate). The transport study in vitro indicated that OPD increased the flux of VCR across MDCK-MDR1 cell monolayer. The in vivo pharmacokinetic parameters data showed OPD increased the absorption of DTX. OPD activated P-gp ATPase activity and enhanced intracellular accumulation of Rh123 in MDCK-MDR1 cells. Western blotting and qRT-PCR outcomes indicated that OPD suppressed P-gp protein expression as well as downregulated P-gp mRNA level. Thus, OPD reverse P-gp-mediated drug transport via inhibition of P-gp activity and P-gp protein expression as well as downregulation of P-gp mRNA level. Our results suggest that OPD could reverse P-gp-mediated drug resistance in tumor cells.

Physical Inactivity, Functional Status and Exercise Capacity in COPD Patients Receiving Home-Based Oxygen Therapy

Chronic obstructive pulmonary disease (COPD) has systemic consequences that lead to reduced physical activity in daily life (PADL). Little is known about PADL and its associations in individuals with COPD on home-based long-term oxygen therapy (LTOT). The objective of the study was to determine whether there is an association between severe physical inactivity and pulmonary function, fatigue, dyspnea, functional status and exercise capacity in individuals with COPD on home-based LTOT using electric oxygen concentrators and to investigate which of these variables could influence inactivity in these individuals. The population sample included 39 individuals with COPD who were on LTOT (69 ± 8 years, FEV₁: 32 ± 14% predicted). They were assessed in terms of PADL (number of steps/day), fatigue (Fatigue Severity Scale - FSS), dyspnea (Medical Research Council - MRC scale), functional status (London Chest ADL scale [LCADL] and Timed Up and Go [TUG] test) and functional exercise capacity (Six-Minute Step test [6MST] and Sit-to-Stand test [STST]). PADL was markedly low (1444 ± 1203 steps/day) and associated with daily duration of LTOT (r = -0.50), fatigue (r = -0.36), LCADL (r = -0.41), 6MST (r = 0.48), and STST (r = 0.53) (p < .05 for all). Multiple linear regression revealed that daily duration of LTOT and STST explained 39% of the variability of PADL. Longer daily duration of LTOT, fatigue, worse functional status and exercise capacity were all associated with physical inactivity in individuals with COPD on LTOT, whereas daily duration of LTOT and the STST were determinants of reduced physical activity.

Measurement Properties of Short Lower Extremity Functional Exercise Tests in People With Chronic Obstructive Pulmonary Disease: Systematic Review

BACKGROUND

An increasing variety of short functional exercise tests are reported in people with chronic obstructive pulmonary disease (COPD). Systematic review of the psychometric properties of these exercise tests is indicated.

PURPOSE

The aim of this study was to determine the reliability, validity, and responsiveness of short (duration < 6 min) lower extremity functional exercise tests in people with COPD.

DATA SOURCES

Five databases were searched: MEDLINE, Embase, Scopus, AMED, and CINAHL.

STUDY SELECTION

Studies reporting psychometric properties of short functional exercise tests in people with COPD were included.

DATA EXTRACTION

Two reviewers independently extracted data and rated the quality of each measurement property using the COnsensus-based Standards for the Selection of Health Measurement INstrument (COSMIN).

DATA SYNTHESIS

Twenty-nine studies were identified reporting properties of 11 different tests. Four-meter gait speed [4MGS] and 5 repetition sit-to-stand [5STS] demonstrated high reliability (ICC = .95-.99; .97) with no learning effect (COSMIN study ratings = good--excellent). Their validity for use as a stratification tool anchored against an established prognostic indicator (area under receiver operator characteristics curve [AUC] = 0.72-0.87; 0.82) and responsiveness to change after pulmonary rehabilitation was greatest in more frail people with COPD. Studies of the Timed "Up and Go" [TUG] test support use of a practice test and show discriminative ability to detect falls history and low six-minute walk distance (AUC = 0.77; 0.82, COSMIN ratings = fair-excellent).

LIMITATIONS

Earlier studies were limited by small sample size. Limited data of lower study quality was identified for step tests and the Two-Minute Walk Test.

CONCLUSIONS

Selected short functional exercise tests can complement established exercise capacity measures, in stratification and measuring responsiveness to change especially in people with COPD and lower functional ability.

The accuracy with which the 5 times sit-to-stand test, versus gait speed, can identify poor exercise tolerance in patients with COPD: A cross-sectional study

Identifying those patients who underperform in the 6-minute walk test (6MWT <350 m), and the reasons for their poor performance, is a major concern in the management of chronic obstructive pulmonary disease.To explore the accuracy and relevance of the 4-m gait-speed (4MGS) test, and the 5-repetition sit-to-stand (5STS) test, as diagnostic markers, and clinical determinants, of poor performance in the 6MWT.We recruited 137 patients with stable chronic obstructive pulmonary disease to participate in our cross-sectional study. Patients completed the 4MGS and 5STS tests, with quantitative (in seconds) and qualitative ordinal data collected; the latter were categorized using a scale of 0 to 4. The following potential covariates and clinical determinants of poor 6MWT were collated: age, quadriceps muscle-strength (QMS), health status, dyspnea, depression, and airflow limitation. Area under the receiver-operating characteristic curve data (AUC) was used to assess accuracy, with logistic regression used to explore relevance as clinical determinants.The AUCs generated using the 4MGS and 5STS tests were comparable, at 0.719 (95% confidence interval [CI] 0.629-0.809) and 0.711 (95% CI 0.613-0.809), respectively. With ordinal data, the 5STS test was most accurate (AUC of 0.732; 95% CI 0.645-0.819); the 4MGS test showed poor discriminatory power (AUC <0.7), although accuracy improved (0.726, 95% CI 0.637-0.816) when covariates were included. Unlike the 4MGS test, the 5STS test provided a significant clinical determinant of a poor 6MWT (odds ratio 1.23, 95% CI 1.05-1.44).The 5STS test reliably predicts a poor 6MWT, especially when using ordinal data. Used alone, the 4MGS test is reliable when measured with continuous data.

Functional Status Assessment of Patients With COPD: A Systematic Review of Performance-Based Measures and Patient-Reported Measures

Presently, there is no recommendation on how to assess functional status of chronic obstructive pulmonary disease (COPD) patients. This study aimed to summarize and systematically evaluate these measures.Studies on measures of COPD patients' functional status published before the end of January 2015 were included using a search filters in PubMed and Web of Science, screening reference lists of all included studies, and cross-checking against some relevant reviews. After title, abstract, and main text screening, the remaining was appraised using the Consensus-based Standards for the Selection of Health Measurement Instruments (COSMIN) 4-point checklist. All measures from these studies were rated according to best-evidence synthesis and the best-rated measures were selected.A total of 6447 records were found and 102 studies were reviewed, suggesting 44 performance-based measures and 14 patient-reported measures. The majority of the studies focused on internal consistency, reliability, and hypothesis testing, but only 21% of them employed good or excellent methodology. Their common weaknesses include lack of checks for unidimensionality, inadequate sample sizes, no prior hypotheses, and improper methods. On average, patient-reported measures perform better than performance-based measures. The best-rated patient-reported measures are functional performance inventory (FPI), functional performance inventory short form (FPI-SF), living with COPD questionnaire (LCOPD), COPD activity rating scale (CARS), University of Cincinnati dyspnea questionnaire (UCDQ), shortness of breath with daily activities (SOBDA), and short-form pulmonary functional status scale (PFSS-11), and the best-rated performance-based measures are exercise testing: 6-minute walk test (6MWT), endurance treadmill test, and usual 4-meter gait speed (usual 4MGS).Further research is needed to evaluate the reliability and validity of performance-based measures since present studies failed to provide convincing evidence. FPI, FPI-SF, LCOPD, CARS, UCDQ, SOBDA, PFSS-11, 6MWT, endurance treadmill test, and usual 4MGS performed well and are preferable to assess functional status of COPD patients.

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.

Validity and Reliability of the 6-Minute Step Test in Healthy Individuals: A Cross-sectional Study

OBJECTIVE

To determine the 6-minute step test's (6MST) reliability and validity and to establish reference performance values of this test.

DESIGN

Prospective observational cross-sectional study.

SETTING

Spirometry and Respiratory Physiotherapy Laboratory, Federal University of São Carlos (institutional).

PARTICIPANTS

Ninety-one individuals [42 men and 49 women, mean age = 39 years (SD, 17 years)] without any diagnosed diseases and with normal exercise capacity [6-minute walk test (6MWT) >75% of the predicted normal].

INDEPENDENT VARIABLES

Participants underwent two 6MST on 1 day and two 6MWT on another day in randomized order. Furthermore, age, gender, height, weight, lower limbs length, abdominal circumference, percentage of body fat, and fat-free mass were obtained.

MAIN OUTCOME MEASURES

Test-retest reliability was assessed by comparing the findings of the two 6MST using the intraclass correlation coefficient (ICC) and Bland-Altman plot. Validity was assessed by comparing outcomes of the 6MST to outcomes of 6MWT using the Pearson correlation coefficient. A multiple regression analysis was conducted using the stepwise method to develop an equation to predict reference values.

RESULTS

The performance (mean steps ± SD) in the first and second test was 149 ± 34 and 149 ± 36 steps, respectively, which was correlated to distance (in meters) in 6MWT (r = 0.72; P < 0.05). Six-minute step test performance was reliable (ICC = 0.9; 95% confidence interval: 0.85-0.93). The equation to predict reference values for the first 6MST was significant (P < 0.001 and R = 0.48): Performance(steps) = 174 to 1.05 × Age(years) to women and Performance(steps) = 209 to 1.05 × Age(years) to men.

CONCLUSIONS

Six-minute step test is a reliable and valid test. Moreover, the number of steps may be predicted by demographic and anthropometric variables with moderate strength of prediction.

CLINICAL RELEVANCE

Six-minute step test is an exercise test that is easy to be conducted, more tolerable than a graded exercise test, requires fewer equipments and space, and permits better monitoring of the participants. The assessment of the reliability, validity, and reference values will provide a better interpretability for clinicians to use it, especially in primary care.

Can we use the 6-minute step test instead of the 6-minute walking test? An observational study

OBJECTIVE

To verify whether or not heart rate is maintained below the calculated submaximal level in healthy, sedentary subjects when they perform the 6-minute step test (6MST) and the 6-minute walking test (6MWT), and to compare the maximal heart rate achieved by the subjects at the end of each test.

DESIGN

Observational, cross-sectional study.

SETTING

One tertiary centre.

PARTICIPANTS

Two hundred and fifty-three participants from a pool of 330 healthy and sedentary subjects between 20 and 80 years of age.

INTERVENTIONS

Both the 6MWT and the 6MST were performed in accordance with the American Thoracic Society's statement. Dyspnoea, blood pressure, oxygen saturation and heart rate were measured before and after each test.

RESULTS

Mean heart rate immediately after the 6MST was significantly higher than mean heart rate immediately after the 6MWT {125 [standard deviation (SD) 19] vs 111 (SD 17) beats/minute; mean difference 13 (95% confidence interval of the difference 10 to 16); P<0.001}. Moreover, mean heart rate during (3minutes after commencement) the 6MST [118 (SD 18) beats/minute] was statistically higher than mean heart rate at the end of the 6MWT [111 (SD 18) beats/minute; P<0.001]. None of the subjects achieved the calculated submaximal heart rate.

CONCLUSIONS

The 6MST and 6MWT are safe and produce submaximal effort in healthy participants. However, they are not interchangeable, and the 6MST requires more energy than the 6MWT.