The use of step tests for the assessment of exercise capacity in healthy subjects and in patients with chronic lung disease

Bibliometric Review of the Step Test: A Comprehensive Analysis of Research Trends and Development

BACKGROUND

The step test provides valuable information on cardiorespiratory parameters such as maximal oxygen uptake and heart rate. Cardiorespiratory capacity is critical to health-related fitness, with heart rate recovery after exercise serving as a predictor of mortality risk.

MAIN BODY

The primary objective of this review was to identify trends, key contributors, and emerging themes in the step test literature through 2023 using the Web of Science Core Collection. Bibliometric data extraction and analysis were performed using a dedicated bibliometric software (VOSviewer). The analysis showed continued interest through 2021. The research categories highlight the multidisciplinary nature of the step test, covering cardiovascular systems, respiratory systems, sports sciences, and medicine. It has gained global attention, with 31 countries involved, with Brazil and the United States leading the way. The diversity of contributing nations is increasing, reflecting a growing global interest. With 111 journals involved, such as Respiratory Care and Medicine and Science in Sports and Exercise, step test research is spread across the academic landscape. With 761 contributing researchers, there is a collaborative and diverse community. The top 10 institutions, including the University of Alabama System and Monash University, illustrate the variety of settings in which step test studies are conducted. Step test studies span multiple disciplines, underscoring their adaptability. The clusters identified in this bibliometric analysis of the step test literature guide future research, suggesting avenues for refining protocols, exploring health implications, optimizing tests for specific conditions such as chronic obstructive pulmonary disease, and adapting step tests in diverse populations.

CONCLUSIONS

Practical implications highlight the role of the step test in cardiovascular risk assessment, fitness monitoring, and rehabilitation. This broad review underscores the relevance of the step test in diverse settings, reflecting its adaptability and ease of application across occupational and clinical settings.

Reproducibility, validity, and reliability of the incremental step test for subjects with moderate to severe asthma

OBJECTIVE

We investigated the measurement properties of the incremental step test in subjects with moderate to severe asthma.

METHODS

Subjects with moderate to severe persistent asthma were recruited from a tertiary university hospital specializing in treating severe asthma. All subjects performed one cardiopulmonary exercise test (CPET) and two incremental step tests (IST) in random sequences. Pulmonary gas exchange was measured during all exercise tests. The measurement properties investigated were reliability by intraclass correlation coefficient (ICC), measurement error by the standard error of measurement and minimum detectable difference, construct validity by Pearson's correlation, and interpretability by the ceiling and floor effects.

RESULTS

Fifty subjects (38 females, mean [SD], age 43.7 [11.6] yr, % FEV1 70 [14.3], BMI 28.5 [5.3] kg/m2) completed the study. The peak oxygen uptake (peak VO2) for the CPET was 27.6 [±6.8] ml/kg/min, for the first IST was 22.3 [±5.3] ml/kg/min and for the second IST was 23.3 [±5.3] ml/kg/min. The IST presented excellent reliability (ICC=0.93, CI95% 0.88-0.96), very good measurement error (2.5%), and construct validity for peak VO2 measurement compared to the CPET (r = 0.85; p < 0.001) to assess exercise capacity in subjects with moderate to severe asthma, with appropriate ceiling (10%) and floor (0%) effects.

CONCLUSION

The IST presented excellent reliability and very good measurement error and validity to assess exercise capacity in subjects with moderate to severe asthma, without ceiling or floor effects.

Use of Intrinsic Entropy to Assess the Instantaneous Complexity of Thoracoabdominal Movement Patterns to Indicate the Effect of the Iso-Volume Maneuver Trial on the Performance of the Step Test

The recent surge in interest surrounds the analysis of physiological signals with a non-linear dynamic approach. The measurement of entropy serves as a renowned method for indicating the complexity of a signal. However, there is a dearth of research concerning the non-linear dynamic analysis of respiratory signals. Therefore, this study employs a novel method known as intrinsic entropy (IE) to assess the short-term dynamic changes in thoracoabdominal movement patterns, as measured by respiratory inductance plethysmography (RIP), during various states such as resting, step test, recovery, and iso-volume maneuver (IVM) trials. The findings reveal a decrease in IE of thoracic wall movement (TWM) and an increase in IE of abdominal wall movement (AWM) following the IVM trial. This suggests that AWM may dominate the breathing exercise after the IVM trial. Moreover, due to the high temporal resolution of IE, it proves to be a suitable measure for assessing the complexity of thoracoabdominal movement patterns under non-stationary states such as the step test and recovery. The results also demonstrate that the instantaneous complexity of TWM and AWM can effectively capture instantaneous changes during non-stationary states, which may prove valuable in understanding the respiratory mechanism for healthcare purposes in daily life.

A Randomized Cross-Over Analysis of the 6-Minute Step Test When Administered in Different Music Listening Conditions to Healthy Young Adults

The 6-Minute Step Test (6-MST) is a simple, inexpensive field test that is increasingly used to evaluate cardiorespiratory fitness. Whether sufficient performance is revealed by this test and the effect on it of motivational factors such as music is unknown. In this cross-sectional, randomized, and crossover research design, we aimed to analyze 6-MST performance and test outcomes in different music-related auditory conditions of non-musical/non-rhythmic [NM/NR], musical/non-rhythmic [M/NR], and musical/rhythmic [M/R]). We had 38 healthy young adults (M age = 21.21, SD = 1.21 years; 60% male) complete all tests, and we measured their number of steps taken, heart rate, blood pressure, respiratory rate, peripheral oxygen saturation, perceived dyspnea, and fatigue on the modified Borg scale. We recorded individually calculated submaximal values according to heart rate reached after three tests. The number of steps increased in the M/R condition relative to other conditions (p = 0.003), and the amount of change in perceived leg fatigue was also higher in the M/R condition (p < 0.017). Despite variable test performances in different auditory conditions, we found no statistically significant difference in cardiovascular fitness and symptoms (p > 0.05). We concluded that the 6-MST is a useful tool for assessing maximum cardiac tolerance, especially if administered while listening to rhythmic music.

Functional Recovery Groups in Critically Ill COVID-19 Patients and Their Associated Factors: From ICU to Hospital Discharge

OBJECTIVES

To analyze functional recovery groups of critically ill COVID-19 survivors during their hospital stay and to identify the associated factors.

DESIGN

Prospective observational multicenter study.

SETTING

Demographic, clinical, and therapeutic variables were collected, and physical and functional status were evaluated. The Barthel index was evaluated at three time points: 15 days before hospitalization, at ICU discharge, and at hospital discharge from the ward.

PATIENTS

Patients with functional independence before COVID-19 diagnosis were recruited from four hospitals and followed up until hospital discharge.

MEASUREMENTS AND MAIN RESULTS

Three groups of functional recovery were described for 328 patients: functional independence ( n = 144; 44%), which included patients who preserved their functional status during hospitalization; recovered functionality ( n = 109; 33.2%), which included patients who showed dependence at ICU discharge but recovered their independence by hospital discharge; and functional dependency ( n = 75; 22.8%), which included patients who were dependent at ICU discharge and had not recovered their functional status at hospital discharge. The factors associated with becoming functionally dependent at ICU discharge were time to out-of-bed patient mobilization (odds ratio [OR], 1.20; 95% CI, 1.11-1.29), age (OR, 1.02; 95% CI, 1.01-1.04), hyperglycemia (OR, 2.52; 95% CI, 1.56-4.07), and Simplified Acute Physiology Score (OR, 1.022; 95% CI, 1.01-1.04). Recovery to baseline independence during ward stays was associated with ICU length of stay (OR, 0.97; 95% CI, 0.94-0.99) and muscle strength (Medical Research Council test) at ICU discharge (OR, 1.13; 95% CI, 1.08-1.18).

CONCLUSIONS

Age, hyperglycemia, and time for patient mobilization out of bed were independent factors associated with becoming physically dependent after their ICU stay. Recovery of physical function at hospital discharge was associated with muscle strength at ICU discharge and length of ICU stay.

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.

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.

Test-Retest Reliability of Home-Based Fitness Assessments Using a Mobile App (R Plus Health) in Healthy Adults: Prospective Quantitative Study

BACKGROUND

Poor physical fitness has a negative impact on overall health status. An increasing number of health-related mobile apps have emerged to reduce the burden of medical care and the inconvenience of long-distance travel. However, few studies have been conducted on home-based fitness tests using apps. Insufficient monitoring of physiological signals during fitness assessments have been noted. Therefore, we developed R Plus Health, a digital health app that incorporates all the components of a fitness assessment with concomitant physiological signal monitoring.

OBJECTIVE

The aim of this study is to investigate the test-retest reliability of home-based fitness assessments using the R Plus Health app in healthy adults.

METHODS

A total of 31 healthy young adults self-executed 2 fitness assessments using the R Plus Health app, with a 2- to 3-day interval between assessments. The fitness assessments included cardiorespiratory endurance, strength, flexibility, mobility, and balance tests. The intraclass correlation coefficient was computed as a measure of the relative reliability of the fitness assessments and determined their consistency. The SE of measurement, smallest real difference at a 90% CI, and Bland-Altman analyses were used to assess agreement, sensitivity to real change, and systematic bias detection, respectively.

RESULTS

The relative reliability of the fitness assessments using R Plus Health was moderate to good (intraclass correlation coefficient 0.8-0.99 for raw scores, 0.69-0.99 for converted scores). The SE of measurement and smallest real difference at a 90% CI were 1.44-6.91 and 3.36-16.11, respectively, in all fitness assessments. The 95% CI of the mean difference indicated no significant systematic error between the assessments for the strength and balance tests. The Bland-Altman analyses revealed no significant systematic bias between the assessments for all tests, with a few outliers. The Bland-Altman plots illustrated narrow limits of agreement for upper extremity strength, abdominal strength, and right leg stance tests, indicating good agreement between the 2 assessments.

CONCLUSIONS

Home-based fitness assessments using the R Plus Health app were reliable and feasible in young, healthy adults. The results of the fitness assessments can offer a comprehensive understanding of general health status and help prescribe safe and suitable exercise training regimens. In future work, the app will be tested in different populations (eg, patients with chronic diseases or users with poor fitness), and the results will be compared with clinical test results.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR2000030905; http://www.chictr.org.cn/showproj.aspx?proj=50229.

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.

Is the Short and Fast Step Test a safe and feasible tool for exploring anaerobic capacities of individuals with coronary heart disease in clinical practice?

BACKGROUND

While its importance in daily living, the anaerobic metabolism is not taken into account in clinical practice. The lack of validated functional performance tests for patients with chronic disabilities may explain this defect. In this context, the Short and Fast Step Test (SFST) was recently developed and validated in healthy volunteers.

AIM

The purpose of this study was to investigate the safety, feasibility and reliability of the SFST, a functional test exploring anaerobic metabolism in coronary patients during cardiac rehabilitation.

DESIGN

This study was a monocentric prospective study.

SETTINGS

This study took place in the rehabilitation center of the University Hospital Center of Dijon, France.

POPULATION

44 coronary patients, addressed for a first cardiac rehabilitation, were included in this protocol.

METHODS

All participants performed three SFST: T1 and T2 (including respiratory gas exchange) the first day of the program and T3 after 3 to 7 days. SFST consists of walking up and down a 17.5cm-high step as many times as possible in 1 minute. Safety was assessed by the percentage of patients who performed the SFST without reporting a fall, or muscular or cardiovascular events. Feasibility was evaluated by the percentage of patients who succeeded in doing the SFST. Reliability was assessed with the number of raised steps in same condition (T1-T3) and different conditions (T1-T2) using a 2-way intraclass correlation coefficient (ICC). Values were given with their 90% confidence interval [90%CI].

RESULTS

The safety was 95.2% [85.8;99.2] for T1, 88.1% [76.6;95.2] for T2 and 90.4% [79.5;96.7] for T3. 100% [93,1;100] of participants completed T1 and T2, 92.9% [82.6;98] T3. An ICC of 0.74 [0.60;0.84] was observed between T1 and T3 and of 0.87 [0.79;0.92] between T1 and T2.

CONCLUSIONS

This study demonstrates the good safety, feasibility and reliability of the SFST to assess anaerobic metabolism in coronary patients in a rehabilitation program.

CLINICAL REHABILITATION IMPACT

These results show that the SFST seems suitable for the evaluation of brief submaximal functional capacity in daily activities. It offers a real possibility to assess such capacity during the cardiac rehabilitation routine.

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.

Effects of Exergames in Women with Fibromyalgia: A Randomized Controlled Study

Objective: Evaluation of the effects of exergames in women with fibromyalgia on the impact of the disease-pain threshold and physical variables-compared to performing stretching exercises. Materials and Methods: Thirty-five women were enrolled in the study and divided by simple randomization into two treatment groups: the control group (n = 19) and the Wii™ (exergames) group (n = 16). Participants were evaluated using the fibromyalgia impact questionnaire (FIQ), algometry, step tests, cardiopulmonary parameters, and fatigue in the lower limbs. The participants underwent treatments for a period of 7 weeks with three 1-hour sessions weekly and were reevaluated after the 10th and the 20th sessions. Results: The exergames group showed significant reduction of their fibromyalgia symptoms, as demonstrated by lower FIQ scores in the key domains on questions regarding missed work, pain, fatigue, problems resting, stiffness, anxiety, and depression. Significant improvements were observed in mean algometric values in the cervical region, the second chondrocostal junction, the lateral epicondyle, left medial knee border, left occipital region, trapezius, supraspinatus, gluteal muscles, and the greater trochanter. Improved cardiovascular adaptation was reflected by decreased systolic blood pressure, reduction in fatigue of the lower limbs assessed by the CR10 Borg scale, and improved exercise capacity assessed by a step test. Conclusion: Exergames have the potential to increase exercise capacity, decrease the impact of fibromyalgia, promote cardiovascular adaptation, reduce fatigue of lower limbs, and improve the pain threshold in women with fibromyalgia.

An Experimental Study of Step Test Index Combined With Heart Rate Variability in Estimating Maximum Oxygen Uptake in Women With Drug Use Disorder

BACKGROUND

Maximal oxygen uptake (VO2max), a vital physiological indicator, has been widely used in many fields. In recent years, the measurement method of VO2max has been widely explored in various populations, but few studies have been conducted for women drug abusers. For the importance of VO2max in the formulation of aerobic exercise intensity for drug users, the present study estimated VO2max using the step test index combined with heart rate variability in women with drug use disorder.

METHODS

Forty women methamphetamine (MA) users without cardiovascular disease and dyskinesia participated in a cardiopulmonary exercise test (CPX) and a 3-minute step test. Each of them performed a heart rate variability (HRV) monitoring test after the step test, and VO2max was estimated by step test index and HRV.

RESULTS

(1) The step test index had a significant positive correlation with VO2max. The standard deviation of normal-to-normal interval (SDNN) had a significant positive correlation with VO2max and a significant positive correlation with the step test index; (2) the R-square values of the estimated VO2max by step test index and post-SDNN for overall MA users were 0.29 and 0.22, with an accuracy of 93.19 and 92.85%, respectively; (3) the R-square values of the estimated VO2max by step test index and post-SDNN in group I were 0.27 and 0.36, respectively, with an accuracy of 94.04 and 93.99%. The R-square value of the estimated VO2max by step test index in group II was 0.44, with an accuracy of 92.65%, however, post-SDNN cannot adequately estimate the VO2max in group II; and (4) there was no significant difference in VO2max obtained by CPX, step test index, or post-SDNN, regardless of overall or grouping variable analysis.

CONCLUSION

The 3-minute step test combined with HRV can estimate the VO2max of women MA users to a certain extent, but the size and the coverage of the sample size should be further considered. In the future, more methods, such as machine learning or artificial neural networks, should be used.

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.

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.

Validation of 6 min step test and 4-m gait speed in children: A randomized cross-over study

INTRODUCTION

Even if 6-min walking test (6MWT) is the criterion standard for functional exercise performance evaluation, new field tests are required as practical alternative. This study aims to establish the validity of the 6-min step test (6MST) and the 4-m gait speed (4MGS) in children.

METHOD

It is a randomized cross-over trial. Sixty one healthy children from 6 to 12 years were recruited. 6MWT, 6MST and 4MGS were randomly performed on three consecutive days. Pulsed oxygen saturation (SpO2), heart rate (HR), dyspnea (VAS) and fatigue (PCERT) were used as outcomes.

RESULTS

The distance walked during 6MWT was correlated to the number of steps during 6MST (r = 0.320; p = 0.013) and not correlated to 4MGS (r = -0.074; p = 0.575). No correlation between number of steps during 6MST and 4MGS (r = -0.129; p = 0.332) was found. HR was lower than the theoretical maximal HR after the tests. The increase in HR was significantly higher for 6MST and significantly lower for 4MGS than for 6MWT and it was higher for 6MST than for 4MGS. Dyspnea and perceived exertion were lower after 6MWT than after 6MST and higher than after 4MGS. They were also higher during 6MST than during 4MGS.

CONCLUSION

The three field tests are feasible in children. The 6MST and 4MGS are not valid surrogates to 6MWT in healthy children for functional exercise performance evaluation. Moreover, the cardio-respiratory response differs between the three tests.

Number of raised steps: A tool to assess brief and intense effort involving anaerobic metabolism

BACKGROUND

Although the initial anaerobic component of exercise adaptation is unavoidable, no specific functional test is available for use in routine non-sporting practice to evaluate it.

OBJECTIVE

To assess the bioenergetic and biomechanical properties of the Short and Fast Step Test (SFST), which consists of walking up and down a step as many times as possible in 1minute and to analyse its ability to explore the initial anaerobic component of effort in comparison to a reference self-paced step test.

METHODS

Overall, 31 healthy subjects (19 women; mean [SD] age, 32.4 [10.2] years) completed a test-retest of a self-paced step test and the SFST, with pre- and post-test measurement of blood lactate concentration and continuous recording of VO₂ and modelling of excess post-exercise oxygen consumption (EPOC), near-infrared spectroscopy (NIRS) of the quadriceps and mechanical power (estimated by the number of steps climbed and 3-D motion analysis).

RESULTS

Both step tests were well tolerated. The reliability of the bioenergetics parameters, number of raised steps, mechanical power and NIRS tissue saturation index was good. Indirect mechanical power (estimated from number of steps) was correlated with direct power (computed from the centre of mass). Lactate accumulation was significantly increased during exercise with only the SFST (mean [SD] increase, 3.86 [3.26]mmolL^-1 from resting values, P<0.05). EPOC was higher with the SFST than the self-paced step test (P<0.05). Only the SFST showed significant correlations between number of steps climbed and EPOC (r=0.84; P<0.001) and decreased tissue saturation index (NIRS) and EPOC area (r=-0.39; P<0.05).

CONCLUSIONS

SFST is feasible, well tolerated, reliable and responsive to explore a brief exercise involving anaerobic metabolism at submaximal intensity. The number of steps taken in 1minute seems a suitable parameter for practical application.

The effect of nasal provocation with a single-dose allergen on the physical and cognitive performance of patients with ragweed allergy

Purpose This study aims to compare the impact of active allergic rhinitis on physical and cognitive abilities of trained allergic athletes to untrained allergic patients. Methods Cognitive, respiratory, and fitness functions were assessed before and after allergen exposure. Participants in both groups were provoked intranasally with ragweed allergen. Results The group of athletes revealed significantly higher average values in peak inspiratory flow and fitness index before and after provocation. In neuropsychological assessments, athletes performed significantly better after allergen provocation in complex working memory capacity. Due to single acute allergen exposure, the size of the nasal cavity and nasal inspiratory peak flow significantly decreased in both groups. The physical performance of both groups did not change after provocation. Executive functions and complex working memory capacity of athletes significantly improved resulting from provocation. Conclusions A single-shot allergen in high dose might cause an increase in mental concentration, which was more pronounced in the group of athletes. This study indicates that acute exposure to allergen cannot affect the physical performance and may result in increased mental focus in patients with allergy notwithstanding the declining respiratory functions.

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.

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.

Reprodutibilidade do teste de caminhada e do degrau de 6 minutos em adultos jovens saudáveis

INTRODUÇÃO: Os testes caminhada de seis minutos (TC6) e degrau de seis minutos (TD6) são meios de avaliação da capacidade funcional. No entanto, pouco se sabe sobre sua reprodutibilidade em adultos jovens.OBJETIVO: Avaliar a reprodutibilidade relativa e absoluta tanto intra quanto inter-avaliadores do TC6 e TD6 em indivíduos adultos jovens.MÉTODOS: Foram avaliados 33 indivíduos adultos jovens aparentemente saudáveis por meio da espirometria; e realizados os testes TC6 e TD6. Três (T1, T2 e T3) TC6 e TD6 foram feitos em cada indivíduo, sendo o último de cada teste realizado por um avaliador diferente. Para a análise intra-avaliadores foram comparados os desempenhos do T1 e T2 enquanto que a análise inter-avaliadores foi feita pela comparação dos desempenhos do T3 com: T1; T2; e escolha do melhor dos primeiros dois testes. Foi calculado o coeficiente de correlação intra-classe (CCI) como medida da reprodutibilidade relativa; o erro padrão de medida; a diferença mínima detectável; traçados gráficos de Bland-Altman e teste ANOVA para analisar a reprodutibilidade absoluta.RESULTADOS: Observaram-se, nos dois testes funcionais, intra e inter-avaliadores, valores excelentes de reprodutibilidade relativa (CCI>0,75) e a reprodutibilidade absoluta mostrou alto erro.CONCLUSÃO: O TD6 e o TC6 apresentaram reprodutibilidade intra e inter-avaliadores excelente para a população adulto jovem, mas altos valores de erro.

Correlação entre o teste de caminhada de seis minutos e o teste do degrau em idosos

O teste do degrau pode ser uma alternativa para substituir o teste de caminhada de seis minutos quando não há um espaço físico amplo para sua realização. Existem, no entanto, poucos dados na literatura comparando e correlacionando ambos os testes. Dessa forma, o objetivo deste estudo foi correlacionar o teste de caminhada de seis minutos com o teste do degrau. Uma amostra de 38 idosos (68,5 ± 2,1 anos) realizou aleatoriamente o teste de caminhada de seis minutos e o teste do degrau, duas vezes cada teste, sendo considerado para fins de análise o maior valor obtido em cada teste. Frequência cardíaca, percepção subjetiva de esforço, de fadiga muscular e o VO2máx estimados ao final do teste do degrau foram significativamente maiores que ao final do teste de caminhada de seis minutos (p=0,001; 0,010; 0,017; 0,001, respectivamente). No presente estudo, não houve correlação entre a distância percorrida no teste de caminhada de seis minutos e o número de subidas e descidas no teste do degrau. Sendo assim, não se pode afirmar que um teste possa substituir o outro, mas levando-se em consideração os valores estatisticamente maiores para o teste do degrau nas variáveis analisadas e, por necessitar de espaço físico mínimo, sugere-se que o teste do degrau pode ser uma alternativa para a avaliação de idosos.