6-Minute walk distance in healthy North Africans older than 40 years: Influence of parity

Effects of Inspiratory Muscle Training on Stress Urinary Incontinence in North African Women: A Randomized Controlled Trial

INTRODUCTION AND HYPOTHESIS

Pelvic floor muscles (PFMs) are involved in respiratory mechanisms. Additionally, stress urinary incontinence (SUI) can affect physical function. This randomized controlled trial was aimed at investigating the effects of inspiratory muscle training (IMT) on SUI severity, PFM function, and physical function in Tunisian women with SUI.

METHODS

Twenty-seven incontinent women were randomly assigned to either the experimental group or the control group. The following parameters were assessed: respiratory muscle strength (RMS; maximal inspiratory and expiratory pressures), SUI severity (Urogenital Distress Inventory-6; Incontinence Impact Questionnaire-7; pad test), PFM function (Modified Oxford Scale, electromyography, and endurance), and physical function (Timed Up & Go test; 6-min walk test; incremental shuttle walking test). IMT was conducted using threshold IMT.

RESULTS

The IMT program significantly reduced the severity of SUI (p < 0.01), improved PFM function (p < 0.001), enhanced physical function (p < 0.01), and increased RMS (p < 0.001).

CONCLUSION

Inspiratory muscle training could be an effective method for improving pelvic floor disorders and physical function in women with SUI.

Developing normative values and predictive models for the 6-minute walk test across diverse adolescent developmental stages

The six-minute walking test (6MWT) is commonly used to measure functional capacity in field settings, primarily through the distance covered. This study aims to establish reference curves for the six-minute walking distance (6MWD) and peak heart rate (PHR) and develop a predictive equation for cardiovascular capacity in Tunisian children and adolescents. A total of 1501 participants (706 boys and 795 girls), aged 10-18 years, were recruited from schools in Tunisia. The Lambda (L), Mu (M), and Sigma (S) methods (LMS method) were employed to develop smoothed percentile curves for 6MWD and PHR. Multivariate linear regression was utilized to formulate a prediction equation for 6MWD. Smoothed percentiles (3rd, 10th, 25th, 50th, 75th, 90th, and 97th) for 6MWD and PHR were presented with age. All variables showed a strong positive correlation (p < 0.001) with a six-minute walking distance (r ranged from 0.227 to 0.558 for girls and from 0.309 to 0.610 for boys), except resting heart rate, which showed a strong negative correlation (girls: r = -0.136; boys: r = -0.201; p < 0.001). Additionally, PHR showed a weak correlation (p > 0.05). The prediction equations, based on age as the primary variable, were established for both genders. For boys: 6MWD = 66.181 + 38.142 × Age (years) (R2 = 0.372; Standard Error of Estimate (SEE) = 122.13), and for girls: 6MWD = 105.535 + 28.390 × Age (years) (R2 = 0.312; SEE = 103.66). The study provides normative values and predictive equations for 6MWD and PHR in Tunisian children and adolescents. These findings offer essential tools for identifying, monitoring, and interpreting cardiovascular functional deficits in clinical and research settings.

Is a patient self-recorded 6 minute walk test equivalent to a formally recorded 6 minute walk test

BACKGROUND

Functional tests such as the 6-minute walk test (6MWT) are used in many areas of medicine to monitor disease progression and outcomes of treatment. They are particularly helpful in Orthopaedic surgery as the outcomes have been shown to be responsive to recovery over time. The 6MWT is typically performed in a controlled supervised environment which may limit its widespread use (Terwee et al., Rheumatology (Oxford), 2006, 45, 890-902). The primary aim is to investigate if a patient measured 6MWT is comparable to a 6MWT performed under formal testing conditions (Täger et al., Int. J. Cardiol. 2014, 176, 94-98).

METHODS

A total of 55 patients undergoing elective primary hip or knee replacement were instructed to use a smart watch to record a 6MWT in their home community environment (C-6MWT). These measurements were compared to a formally tested 6MWT (F-6MWT) at 2 separate time periods-6 and 12 weeks post-surgery.

RESULTS

At 6 weeks post operation the Intraclass Correlation Coefficient between a formally tested and a patient self-administered 6MWT was 0.928 (95% CI 0.832-0.970) and at 12 weeks it was 0.831 (0594-0.935).

CONCLUSION

A patient recorded 6 minute walk test shows high agreement with a formally recorded one under research conditions. This makes this test a suitable way to monitor rehabilitation progression and research outcomes at multiple time periods and in remote situations.

Normative values in healthy adults for the 6-minute and 2-minute walk tests in Belgium and Vietnam: implications for clinical practice

OBJECTIVE

To establish reference values for the 6-minute walk test (6MWT) and 2-minute walk test (2MWT) distances, to investigate the correlation between these 2 tests, and to establish prediction equations for these distances in healthy populations of Belgium and Vietnam.

DESIGN

Cross-sectional study.

SUBJECTS AND METHODS

The 6MWT and 2MWT were administered to a convenience sample of 239 Belgian and 303 Vietnamese participants between the ages of 18 and 80 years.

RESULTS

The mean (standard deviation; SD) 2MWT distances were 215 (32.8) m for Belgian participants and 156 (25.5) m for Vietnamese participants. The mean (SD) 6MWT distances were 625 (90.7) m for Belgian participants and 449 (70.4) m for Vietnamese participants. The Pearson correlation coefficient between the 2 tests was 0.901 (p < 0.001) for Belgian participants and 0.871 (p < 0.001) for Vietnamese participants. Age and sex were the 2 most important predictors of walking distance, followed by body mass index for Belgium and height for Vietnam. The adjusted R² ranged from 0.31 to 0.49 across 4 predictive equations.

CONCLUSION

These results can be used to determine the presence of walking performance deficits and to guide future studies. The 2MWT is suggested as a useful and convenient alternative to the 6MWT for assessing walking performance in clinical practice.

Pregnancy reference intervals and exertion and breathlessness ratings for the six minute walk test in healthy nulliparous people

Background

The Six Minute Walk Test (6MWT) is a simple, non-invasive, well-validated test that assesses cardiorespiratory fitness however is rarely used in pregnant people. It may have clinical utilization to assess fitness, breathing and exertion in pregnancy however no reference intervals exist for people 14+0 to 35+6 weeks gestation. We determined the reference intervals for distance walked for the 6MWT, including exertional and breathlessness ratings for this group.

Method

We conducted a prospective observational cohort study of 196 healthy nulliparous pregnant people in earlier pregnancy (EP) 14+0 to 23+6 weeks, and middle pregnancy (MP) 24+0 to 35+6 gestation, who performed a standardized 6MWT protocol including rating exertion and breathlessness (Rating Perceived Exertion (RPE) scale (1 none -15 maximal) and Modified Borg Dyspnea (MBD) scale (0 none - 10 maximal)).

Results

The mean ± SD distance walked was 548 ± 80.9 (EP) versus 547 ± 87.3 (MP) meters (m) P = 0.928. 6MWT reference intervals for the distance walked for the 6MWT were 392-704 m (EP) and 376-718 m (MP). Median (IQR) exertion and breathlessness ratings with exercise for the EP and MP group were 6 (4,7) and 0.5 (0,1) and 6 (4,8) and 0.5 (0,1) respectively. There were no adverse events.

Conclusion

The 6MWT is safe, feasible and acceptable in pregnant people. The reference intervals for the 6MWT are 392-704 m in people 14+0 to 23+6 weeks gestation and 376-718 m for people 24+0 to 35+6 weeks gestation. Exertion was light and breathlessness was just noticeable with the 6MWT.

Feasibility of a home-designed respiratory rehabilitation program for chronic obstructive pulmonary disease

BACKGROUND

According to international guidelines, respiratory rehabilitation (RR) for patients with chronic obstructive pulmonary disease (COPD) is a cornerstone of standard non-pharmacological treatment.

AIMS

To evaluate feasibility of a home-designed RR program and analyze its medium-term impact on respiratory parameters and quality of life.

METHODS

This was a prospective study involving 74 COPD patients enrolled in January 2019 and put on inhaled bronchodilator treatment associated with RR at home following a written protocol, for 16 weeks. The comparative statistical analysis highlights the difference before and after RR in terms of clinical and functional respiratory parameters as well as in terms of quality of life (assessed on the short form 36 (SF-36) questionnaire). The comparison involves RR-adherent patients versus non-adherent patients.

RESULTS

Mean age was 66.7 ± 8.3 years with a median of 67 years. All patients were smokers, out of which 42 patients (57%) did not quit yet. Forty-one percent of patients were frequent exacerbators. The average COPD assessment test (CAT) score in our patients was 23. The average 6-minutes walk distance (MWD) was 304 m. The BODE index in our patients was 4.11 on average. The RR program was followed by 36 patients (48%). Thirty patients (40%) applied it at least twice a week. RR-adherent patients had an average CAT score decreasing from 23 to 14.5 (P = 0.011). Their average 6-MWD was 444.6 m by the end of the study, which would be 64.2% of the calculated theoretical value. The average FEV1 increase after RR was 283 mL. The majority (69%) of RR-adherent patients were ranked as quartile 1; BODE index ≤2. The average scores of physical, psycho-social, and general dimensions assessed on the SF-36 questionnaire improved in RR-adherent patients.

CONCLUSIONS

RR is a key non-pharmacological treatment for COPD. Its interest originates from its multidisciplinary nature, hence its effectiveness in several respiratory parameters. Our study reflects the feasibility of home-designed protocols in the absence of contraindications. We highlight also the positive impact on quality of life after RR at home.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Effects of cardiorespiratory rehabilitation program on submaximal exercise in patients with long-COVID-19 conditions: a systematic review of randomized controlled trials and recommendations for future studies

INTRODUCTION

Long-COVID-19 patients (LC19Ps) often experience cardiovascular and respiratory complications. Cardiorespiratory rehabilitation programs (CRRPs) have emerged as promising interventions to enhance exercise capacity in this population. This systematic review aimed to assess the impact of CRRPs on submaximal exercise performance, specifically the 6-minute walk test (6MWT) outcomes, in LC19Ps through an analysis of available randomized controlled trials (RCTs).

METHODS

A systematic search was conducted in PubMed/Medline and Scopus to identify relevant RCTs. Six RCTs meeting inclusion criteria were included in this review, investigating the effects of CRRPs on 6MWT outcomes in LC19Ps.

RESULTS

The findings from the included RCTs provide compelling evidence supporting the effectiveness of CRRPs in improving submaximal exercise performance in LC19Ps. These results underscore the potential of CRRPs to enhance submaximal exercise capacity and overall functional well-being in this population. However, future research is imperative to determine optimal CRRPs, including duration, intensity, and specific intervention components. Additionally, the long-term sustainability and durability of CRRP-induced improvements warrant further exploration. Future studies should prioritize patient-centric outcomes and address potential implementation barriers.

CONCLUSION

CRRPs show promise in ameliorating submaximal exercise performance among LC19Ps. Further research is needed to refine these programs and ensure their lasting impact on this patient group.

SYSTEMATIC REVIEW REGISTRATION

https://doi.org/10.17605/OSF.IO/HMN38. [Figure: see text].

Heart Rate Response Predicts 6-Minutes Walking Distance in Pulmonary Arterial Hypertension

Because the 6-minute walking test (6MWT) is a self-paced submaximal test, the 6-minute walking distance (6MWD) is substantially influenced by individual effort level and physical condition, which is difficult to quantify. We aimed to explore the optimal indicator reflecting the perceived effort level during 6MWT. We prospectively enrolled 76 patients with pulmonary arterial hypertension and 152 healthy participants; they performed 2 6MWTs at 2 different speeds: (1) at leisurely speed, as performed in daily life without extra effort (leisure 6MWT) and (2) an increased walking speed, walking as the guideline indicated (standard 6MWT). The factors associated with 6MWD during standard 6MWT were investigated using a multiple linear regression analysis. The heart rate (HR) and Borg score increased and oxygen saturation (SpO2) decreased after walking in 2 6MWTs in both groups (all p <0.001). The ratio of difference in HR before and after each test (ΔHR) to HR before walking (HRat rest) and the difference in SpO2 (ΔSpO2) and Borg (ΔBorg) before and after each test were all significantly higher in both groups after standard 6MWT than after leisure 6MWT (all p <0.001). Multiple linear regression analysis revealed that ΔHR/HRat rest was an independent predictor of 6MWD during standard 6MWT in both groups (both p <0.001, adjusted R2 = 0.737 and 0.49, respectively). 6MWD and ΔHR/HRat rest were significantly lower in patients than in healthy participants (both p <0.001) and in patients with cardiac functional class III than in patients with class I/II (both p <0.001). In conclusion, ΔHR/HRat rest is a good reflector of combined physical and effort factors. HR response should be incorporated into 6MWD to better assess a participant's exercise capacity.

Reference standards for the 6-min walk test in Croatian older adults

Introduction: The 6-min walk test (6MWT) is commonly used to assess the level of functional capacity of individuals with respiratory diseases. Although previous evidence has provided reference standards for the 6MWT in unhealthy older adults, no data have been provided for the Croatian healthy older populations. Therefore, the main purposes of the study were to define sex- and age-specific references for the 6MWT in older adults. Methods: Six-hundred and forty-three older adults (260 men and 383 women) aged 60-80 years were recruited in this observational cross-sectional study. The participants were instructed to walk the maximal distance possible for 6 min. The main outcome was the final score in the 6MWT conducted at a 30-m straight corridor. Results: Men exhibited longer walking distance, compared to women (678.3 ± 59.1 vs. 653.8 ± 49.9 m, p < 0.001) and younger men and women performed better, than their older counterparts (p < 0.001). However, the sex*age interaction effect showed no significant differences between men and women in the same age range (p = 0.865). Discussion: This is the first study with the purpose of providing reference standards for the 6MWT in a large sample of Croatian older adults. Older men and women in lower percentiles may be treated as a "risky group" of individuals with a special attention of implementing interventions to enhance the performance.

Independent predictors and equation of six-minute walk test in post-cardiac surgery

BACKGROUND

The six-minute walk test (6MWT) has been used to evaluate postsurgical recovery in cardiac patients. No previous study has compared the 6MWT at follow-up with a baseline, or evaluated the long-term effects of cardiac surgery on post-discharge 6MWT OBJECTIVES: To identify the factors independently associated with 6MWD, and to develop an equation to predict 6MWT at the 4-6-week follow-up after post-cardiac surgery hospital discharge.

METHODS

Patient data of elective coronary artery bypass graft (CABG) or non-CABG surgery patients were retrospectively collected. The 6MWT was performed at hospital discharge and at the 4-6-week follow-up. Available demographic and clinical data of patients were analyzed to determine the independent factors of 6MWT. An equation to predict 6MWT were generated by forward stepwise multiple linear regression analysis.

RESULTS

The data of 275 patients (mean age: 62.20±14.57 years, 64.7% male) were analyzed. The mean 6MWT was 179.14±92.18 m at discharge, and increased to 335.20±115.51 m at the 4-6-week follow-up. The 6MWT at the 4-6-week follow-up was independently correlated with 6MWT at discharge, regular exercise, age, gender, and preoperative New York Heart Association (NYHA) classification.

CONCLUSION

The independent predictors: 6MWT at discharge, regular exercise, age, gender, and NYHA classification were used to generate an equation to predict 6MWT at 4-6 weeks after hospital discharge.

Normative reference values and regression equations to predict the 6-minute walk distance in the Asian adult population aged 21-80 years

SUMMARY AT A GLANCE

The 6-min walk test (6MWT) is a widely used field walking test. This study reports the normative reference values (NRV) of distance walked during 6MWT (6MWD) in healthy Singaporeans (aged 21-80) and updates the 6MWD reference equations. This information may facilitate the interpretation of the 6MWD in clinical populations.

ETHICS APPROVAL

The Singapore Institute of Technology-Institutional Review Board (SIT-IRB Project Number: 2019099) approved this study to be carried out from June 2019 to January 2021. All participants gave written informed consent before data collection began.

BACKGROUND

The six-minute walk test (6MWT) is a widely adopted submaximal field-walking test to evaluate functional exercise capacity. This validated test is a reliable, safe, inexpensive, and straightforward assessment tool commonly used as an outcome measure, using the distance walked (6MWD) as the primary outcome. An earlier study has established the normative reference values (NRV) and equation in healthy Singaporeans - however, the small sample size and narrow age range curb adequate representation of the adult population profile.

OBJECTIVES

This study aims to update the NRV and reference equations to predict the distance walked during 6MWT (6MWD) for healthy Singaporeans aged 21-80.

METHODS

This cross-sectional study recruited community-dwelling healthy subjects aged 21-80 via convenience sampling. Each subject completed two trials of 6MWT according to the standard protocol. Primary outcome measures included 6MWD, pre-and post-test heart rate (HR), oxygen saturation, and blood pressure (BP).

RESULTS

172 healthy Singaporeans (females = 90 , males = 82 ) participated. The overall mean 6MWD was 578 . 00 ± 75 . 38 metres. The age-stratified mean 6MWD ranged from 601 . 3 ± 71 . 79 metres (aged 21-39) to 519 . 02 ± 55 . 42 metres (aged 60-80). Age, gender, and percentage maximum HR predicted (%PredHRmax) were the most significant variables (p < 0 . 001 ). 6MWD reference equation = 288 . 282 ( height , m )+ 27 . 463 × Gender ( male = 1 ; female = 0 )+ 4 . 349 ( % predHRmax )+ 1 . 191 (HR reserve, bpm) - 185 . 431 - 1 . 343 ( age , years )- 1 . 614 (weight, kg), R 2 = 58 % . Applying equations from other studies to the Singaporean population resulted in an overestimation of the 6MWD.

CONCLUSION

This study updated the NRV and reference equations of 6MWD for healthy Singaporeans aged between 21-80 years. This update revises the local benchmarks of 6MWD in Singapore, a widely adopted outcome measure.

Why a large percentage of Tunisian women aged 40 years and more has a reduced forced vital capacity? The implication of parity

The investigation of the link between reduced forced vital capacity (FVC) and risk factors and health variables in women aged ≥ 40 years is encouraged since a reduced FVC was related to all-cause mortality. The high frequency of women with a reduced FVC, observed in some studies, could be related to the impacts of parity on lung. In the literature, the association between parity and health consequences is discussed in terms of “selection pressure”, and the trade-off between longevity and fertility described by scientists is termed the “longevity determination” or “biological warranty period”. The respiratory system could be influenced by parity. Above all, it is the respiratory system, who endures the repercussions of the numerous physio-pathological experiences of the woman life. The probable effects of parity on lung function data, including FVC, make parity a key predictor to be stressed and evaluated. Parity is a promising original direction for physiological and pathophysiological research, particularly for low- and lower-middle- income countries. Thus, upcoming epidemiological and clinical studies of lung function data in women would need to include information about their parity status.

Evaluation of physical health status beyond daily step count using a wearable activity sensor

Physical health status defines an individual's ability to perform normal activities of daily living and is usually assessed in clinical settings by questionnaires and/or by validated tests, e.g. timed walk tests. These measurements have relatively low information content and are usually limited in frequency. Wearable sensors, such as activity monitors, enable remote measurement of parameters associated with physical activity but have not been widely explored beyond measurement of daily step count. Here we report on results from a cohort of 22 individuals with Pulmonary Arterial Hypertension (PAH) who were provided with a Fitbit activity monitor (Fitbit Charge HR^®) between two clinic visits (18.4 ± 12.2 weeks). At each clinical visit, a maximum of 26 measurements were recorded (19 categorical and 7 continuous). From analysis of the minute-to-minute step rate and heart rate we derive several metrics associated with physical activity and cardiovascular function. These metrics are used to identify subgroups within the cohort and to compare to clinical parameters. Several Fitbit metrics are strongly correlated to continuous clinical parameters. Using a thresholding approach, we show that many Fitbit metrics result in statistically significant differences in clinical parameters between subgroups, including those associated with physical status, cardiovascular function, pulmonary function, as well as biomarkers from blood tests. These results highlight the fact that daily step count is only one of many metrics that can be derived from activity monitors.

Influence of parity on six-minute walk test in Indian females

Six-minute walk test (6MWT) is a simple test measuring submaximal functional capacity. Various factors such as anthropometric, demographic, and physiological characteristics, are associated with functional decline. However, few authors have dealt with the link between functional decline and parity. Thus, the researchers aimed to measure the six-minute walk distance (6MWD) in healthy Indian women and to determine the factors influencing 6MWD in Indian females, with particular attention to parity. Two hundred asymptomatic females aged 45-60 years were recruited for this cross-sectional study based on selection criteria. A single 6MWT was performed and a 6MWD was recorded. Mean ± SD 6MWD was 483.03 ± 50.22 m. Parity significantly affected the 6MWD among Indian females (r = 0.418, p = 0.0001). Parity is an important factor influencing female functional capacity and should be considered when assessing and prescribing rehabilitation in female participants.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

LEVEL OF EVIDENCE

III, Cohort study.

Impact of cardiorespiratory rehabilitation program on submaximal exercise capacity of Tunisian male patients with post-COVID19: A pilot study

Post-COVID19 patients suffer from persistent respiratory, cardiovascular, neurological, and musculoskeletal health complaints such as dyspnea, chest pain/discomfort, and fatigue. In Tunisia, the potential benefits of a cardiorespiratory rehabilitation program (CRRP) after COVID19 remain unclear. The main aim of this study was to evaluate the impact of a CRRP on submaximal exercise capacity, evaluated through the 6-min walk test (6MWT) data in post-COVID19 Tunisian patients. This was a cross-sectional study including 14 moderate to severe COVID19 patients aged from 50 to 70 years. CRRP was performed after the end of patients’ hospitalization in COVID19 units for extensive or severe extents of COVID19. Dyspnea (modified medical research council), spirometry data, handgrip strength values, 6MWT data, and 6-min walk work (i.e., 6-min walk distance x weight) were evaluated 1-week pre-CRRP, and 1-week post-CRRP. CRRP included 12 sessions [3 sessions (70 min each)/week for 4 weeks]. Exercise-training included aerobic cycle endurance, strength training, and educational sessions. Comparing pre- and post- CRRP results showed significant improvements in the means±standard deviations of dyspnea by 1.79 ± 0.80 points (p < 0.001), forced expiratory volume in one second by 110 ± 180 ml (p = 0.04), 6-min walk distance by 35 ± 42 m (p = 0.01), 6-min walk work by 2,448 ± 3,925 mkg (p = 0.048), resting heart-rate by 7 ± 9 bpm (p = 0.02) and resting diastolic blood pressure by 6 ± 10 mmHg (p = 0.045). In Tunisia, CRRP seems to improve the submaximal exercise capacity of post-COVID19 patients, mainly the 6-min walk distance and work.

An Alternative Prediction Equation for Evaluation of Six-Minute Walk Distance in Stable Coronary Artery Disease Patients

Background: As cardio-vascular diseases are the leading cause of death worldwide, establishing measures to improve cardiovascular health is of crucial importance. Exercise plays an essential role in cardiac rehabilitation of patients with coronary artery disease (CAD), in whom an evaluation of the cardiorespiratory fitness (CRF) is necessary. CRF of CAD patients could be assessed using 6-min walk test (6MWT), and the results interpreted by using Enright-Sherill prediction equation which has mainly been designed and evaluated for a healthy population. Hypothesizing that the Enright-Sherill prediction equation might not be best suited for CAD patients, our aim was to reevaluate this equation in CAD patients, and potentially establish a more accurate 6MWD prediction equation to be applied in these patients.

Methods: 6MWD was measured in a cross-sectional study in 67 CAD patients (44 women) who were members of the Coronary club Ljubljana, Slovenia. In addition, the predicted 6MWD was calculated for men and women using Enright-Sherill gender specific regression equation. Multivariate regression analysis was used to obtain a new prediction equation, and the agreement between the measured and the predicted 6MWD analyzed using the repeated measures ANOVA.

Results: Men achieved 451 ± 122 m and women 485 ± 69 m without significant differences between sexes (F = 0.022, p = 0.882) when adjusted for age, height, body mass, and waist circumference. When comparing the measured (473 ± 91 m) and the predicted (422 ± 57 m) values of 6MWD in CAD patients we found that the Enright-Sherill prediction equation significantly (F = 27.734, p &lt; 0.001) underestimated the 6MWD by 52 ± 81 m. A significant regression equation was established [F (3,63) = 44.663, p &lt; 0.001], with a R2 of 0.680 where 6MWD equals 1,057 m—4.966 x age (years)—0.614 x WC (cm)–68.629 x NYHA class.

Conclusion: The results of this study stress the importance of regular and actual walking ability testing in patients with stable CAD to obtain their CRF, rather than simply predicting it from regression equations obtained from non-representative or non-comparable samples. Our developed prediction equation warrants additional validation and may represent a good substitute for currently used predictions obtained from a healthy population.

Deficiency, incapacity and social disadvantage of patients with chronic hepatitis B: a case-control study

INTRODUCTION

Studies examining impairment, disability and social disadvantage of patients with chronic viral hepatitis B (CHB) are scarce and present conflicting conclusions.

AIM

To assess the deficiency, incapacity, and social disadvantage of patients with CHB.

METHODS

This is a project of a case-control study with two age-matched groups. Cases (n=27) will be untreated patients with a CHB. Controls (n=27) will be healthy participants. The following data will be collected: deficiency [anthropometric, biochemical (renal and hepatic functions, lipid balance, and inflammatory markers), haematological, virological, handgrip-strength, and spirometric data], incapacity [6-min walk distance, number of stops, oxy-haemoglobin saturation, dyspnoea (visual analogue scale), heart-rate, and blood-pressure] and social disadvantage ["chronic liver disease" and physical-activity questionnaires]. Each spirometric data < lower-limit-of-normal will be considered abnormal. A handgrip-strength <26 kg (male) or <16 kg (female) will be considered low. The signs of walking intolerance will be: stop during the walk, 6-min walk distance ≤ lower-limit-of-normal, dyspnoea at the end of the walk> 5/10, drop in oxy-haemoglobin saturation >5 points, heart-rate at the end of the walk ≤60%. A total physical-activity score <9.42 will classify the participant as sedentary.

EXPECTED RESULTS

Compared with controls, cases will have a marked alteration of submaximal aerobic data. These alterations will worsen quality-of-life and may be related to muscle and/or spirometric abnormalities, and supported by systemic inflammation and high viral load.

A modified six-minute walk test (6MWT) for low-resource settings-a cross-sectional study

BACKGROUND

The 6 min walk test (6MWT) is a validated tool used to assess functional capacity in a variety of patient populations. Space constraints often limit the practicality of the 6MWT according to the standard (2002) American Thoracic Society protocol, and therefore, adaptations to this protocol are common with potential implications for research and clinical practice. Furthermore, such implications for research and clinical practice may be augmented in low-resourced settings.

OBJECTIVES

To determine the agreement between the 6 min walk distance (6MWD) achieved on the standard 30 m (6MWT₃₀), and a straight 10 m (6MWT₁₀), or 10 m figure-of-eight (6MWT_F8) configuration, respectively.

METHODS

A cross-sectional study was conducted in a socioeconomic challenged community. A heterogeneous sample of adults (n = 27) with non-communicable disease were randomized into performing the 6MWT₁₀ (n = 15) or 6MWT_F8 (n = 12), in addition to the standard 6MWT₃₀. Pairwise comparison and concordance correlation coefficients were used to assess agreement.

RESULTS

The mean (SD) 6MWD₃₀ was 437(42) meters, while the mean 6MWD₁₀ was 371(57). The mean difference (SE; p-value) between the 6MWD₃₀ and 6MWD₁₀ was 67 m (8.6; p .01). The mean 6MWD₃₀ was 424(67) meters, while the mean 6MWD_F8 was 347(58). The mean difference between the 6MWD₃₀ and 6MWD_F8 was 77 m (6.0; p .01). Moderate concordance was found between the 6MWT₃₀ and 6MWT_F8 or 6MWD₁₀, respectively.

CONCLUSIONS

The present data suggest that, independent of configuration, using a shorter pathway significantly reduced the 6MWD. Low-resource settings may benefit from contemporary measures of functional capacity more conducive to resource constraints, or standardization of the test when used in such settings.

Reference values and regression equations for predicting the 6-minute walk distance in Saudi adults aged 50-80 years: A cross- sectional study

BACKGROUND

The 6-minute walk test (6-MWT) is commonly used to measure functional capacity in clinical and research settings. The reference equations for predicting the 6-minute walk distance (6-MWD) in different populations have been established; however, there is a lack of information regarding healthy Saudi individuals over 50 years old.

OBJECTIVES

This study aimed to establish the reference values of 6-MWD in a sample of healthy Saudi adults aged 50-80 years, develop regression equations for the established 6-MWD, and compare the measured 6-MWD in the present study with the predicted 6-MWD derived from the previously published regression equations.

METHODS

In total, 210 healthy Saudi volunteers aged 50-80 years participated in this cross-sectional study. The 6-MWT was performed according to the American Thoracic Society (ATS) guidelines. Lung function, physical activity, blood pressure, heart rate, oxygen saturation, exertion level of leg fatigue, and sensation of dyspnea were measured.

RESULTS

The mean 6-MWD was 396.2 ± 69.4 m. It was significantly correlated with age, sex, height, body mass index (BMI), and physical activity. The predictors of 6-MWD were age and BMI for men, while they were age, BMI, and height for women. They accounted for 25% and 35% of the total variance of 6-MWD for men and women, respectively. The measured 6-MWD was significantly shorter than the predicted 6-MWD.

CONCLUSION

Saudi populations have significantly shorter 6-MWDs than those reported in other ethnic groups. The sex-specific equations developed in this study are expected to provide a useful measure of 6-MWT for Saudi adults. However, further investigation is required to validate the application of these equations to individuals living in different regions of Saudi Arabia.

Six-minute walk test protocol variations in low-resource settings - A scoping review

BACKGROUND

The 6-min walk test (6MWT) is a validated tool, of submaximal intensity, used to objectively measure functional exercise capacity. In 2002, the American Thoracic Society (ATS) developed guidelines on standardising the implementation of the 6MWT. Despite the relative ease of conducting the 6MWT as per these guidelines, adaptations are implemented.

OBJECTIVES

Identify (1) what 6MWT adaptations to the ATS guidelines have been described in low-resource settings (LRS), (2) the purpose of the adapted 6MWT and (3) the reported argumentation for making these adaptations in relation to the specific context.

METHODS

Five databases were searched from inception until February 2021. Studies that adapted and conducted the 6MWT in LRS were included. Data concerning the study source, participants, 6MWT: purpose, variations, outcome and rationale were extracted.

RESULTS

A total of 24 studies were included. The majority of studies (n = 18; 75%) were conducted in lower-middle income countries. The most common adaptation implemented was variation to course length. Eight studies provided a rationale for adapting the 6MWT. Space constraint was the most common reason for adaptation.

CONCLUSION

The most common reason (space constraints) for adapting the 6MWT in LRS was addressed through adaptations in course length and/or configuration. The results of this review suggest that the value of the ATS-guided 6MWT in LRS may need to be re-evaluated.

CLINICAL IMPLICATIONS

Using adapted forms of the 6MWT may lead to an underestimation of a patient's abilities, misinformed discharge and developing inappropriate exercise programmes. Additionally, diverting from ATS guidelines may affect the continuity of care.

The impacts of parity on spirometric parameters: a systematic review

Introduction: The relationship between parity and health outcomes has been debated in the scientific literature in terms of 'selection-pressure'. However, no previous review has raised the impacts of parity on spirometric parameters. This Systematic Review aimed to review the impacts of parity on spirometric parameters.Areas covered: PubMed and Scopus were searched on October 1^st, 2020, using the combination of the following two medical subject headings: 'Parity' and 'Respiratory Function Tests'. Only original articles published in English/French were retained. Ten studies investigated the impacts of parity on spirometric parameters: six included healthy females, three involved unhealthy females [chronic obstructive pulmonary disease, defect in protease inhibitor, and some other conditions] and one included a mixed population of healthy/unhealthy females. The studies reported conflicting results: no impact, positive impact (multiparity is associated with larger forced-expiratory-volume in one second, forced- and slow- vital-capacity, and inspiratory-capacity), or negative impact (multiparous females has lower bronchial flows, higher static volumes, an accelerated lung-aging, a tendency to an obstructive-ventilatory-defect and/or to lung-hyperinflation, and increased protease inhibitor levels).Expert opinion: The ten studies presented some limitations that made data interpretation relatively difficult. Future research to identify the 'real' impact of parity on spirometric parameters are therefore encouraged.

The Chronic Effects of Narghile Use on Males' Cardiovascular Response During Exercise: A Systematic Review

Narghile use has regained popularity throughout the world. Public opinion misjudges its chronic harmful effects on health, especially on the cardiovascular system. This systematic review aimed to evaluate the chronic effects of narghile use on cardiovascular response during exercise. It followed the preferred reporting items for systematic reviews guidelines. Original articles from PubMed and Scopus published until January 31, 2020, written in English, and tackling the chronic effects of narghile use on human cardiovascular response during exercise were considered. Five studies met the inclusion criteria. Only males were included in these studies. They were published between 2014 and 2017 by teams from Tunisia (n = 4) and Jordan (n = 1). One study applied the 6-min walk test, and four studies opted for the cardiopulmonary exercise test. Narghile use was associated with reduced submaximal (e.g., lower 6-min walk distance) and maximal aerobic capacities (e.g., lower maximal oxygen uptake) with abnormal cardiovascular status at rest (e.g., increase in heart rate and blood pressures), at the end of the exercise (e.g., lower heart rate, tendency to chronotropic insufficiency) and during the recovery period (e.g., lower recovery index). To conclude, chronic narghile use has negative effects on cardiovascular response to exercise with reduced submaximal and maximal exercise capacities.

Contribution of lung function in predicting distance covered in the 6-min walk test in obese Brazilian women

Obesity affects the respiratory system through various mechanisms, including systemic inflammation and direct mechanical hindrance due to fat deposition in the chest and abdomen. In addition, changes in the neural control of respiration and increases in thoracic blood volume can promote abnormalities in lung function. Thus, determining relationships between the distance covered in the 6-min walk test (6MWT) and demographic and lung function variables may help us better understand the mechanisms involved in reduced functional exercise capacity in obesity. To explore the determinants of the 6-min walking distance (6MWD) and evaluate the influence of lung function on the distance covered, 263 obese Brazilian women performed the 6MWT and underwent spirometry and respiratory muscle strength measurement. The mean age was 41.8±11.1 years. The mean body mass index (BMI) was 45±8 kg/m². The 6MWD showed correlations with height (r=0.319), age (r=-0.281), weight (r=-0.370), BMI (r=-0.561), forced vital capacity (FVC, r=0.443), expiratory peak flow (r=0.278), maximal inspiratory pressure (MIP, r=0.326), and maximal expiratory pressure (r=0.259), all with P<0.0001. In the stepwise forward regression analysis, BMI, FVC, age, and MIP were the independent predictive variables for 6MWD, explaining 41% of its variability. The reference equation including lung function was as follows: 6MWD (m) = 513.6 - (4.439 × BMI_kg/m2) + (1.136 × FVC_%predicted) - (1.048 × age_yrs) + (0.544 × MIP_%predicted). Thus, the inclusion of lung function in a reference equation for 6MWD contributes to a better prediction of the distance covered in this population.

Six-minute walking distance in healthy Chinese people older than 60 years

Background

The six-minute walking test (6MWT) is a tool that plays a key role in evaluating the functional exercise capacity, prognosis and evaluation of treatment response of patients with various cardiopulmonary diseases. However, standard reference equations are currently unavailable for the six-minute walking distance (6MWD) for people aged 60–85 years in China. The purpose of this study was to 1) measure the 6MWD of healthy Chinese people aged 60–85 years, 2) establish reference equations for predicting the 6MWD, and 3) compare our reference equations with equations reported in previously published studies.

Method

We obtained informed consent from each participant prior to the test, and the research design was approved by the Ethics Committee of Wenzhou People’s Hospital. The demographic and anthropometric data and the 6MWD of healthy Chinese subjects aged 60–85 years old were measured using a standardized protocol. Every subject completed two 6MWTs, and the longest 6MWD further analyzed.

Results

Two hundred sixty-six subjects (128 males and 138 females) completed the 6MWT, and the mean walking distance was 518 ± 72 m. Males achieved a longer walking distance than females (518 ± 72 m vs. 487 ± 70 m; p < 0.0001), and active subjects achieved a longer walking distance than nonactive subjects (512 ± 76 m vs. 485 ± 63 m; p < 0.0001). According to the univariate analysis, the 6MWD was significantly associated with age, height, body mass index (BMI), heart rate and blood pressure after exercise and changes in heart rate before and after exercise. The stepwise multivariate regression analysis identified age, height and BMI as independent predictors of the 6MWD. The reference equations for Caucasians and South Americans tended to overestimate the 6MWD of our subjects, while the equations for Asian and African populations tended to underestimate the 6MWD.

Conclusions

This study is the first to describe the 6MWD of healthy Chinese people aged 60–85 years, and reference prediction equations were proposed. These findings will help to improve the evaluation of Chinese patients with diseases that affect exercise capacity.

Enhancing the assessment of cardiorespiratory fitness using field tests

OBJECTIVE

To establish normative values and reference equations of the 6-minute walk test (6MWT), incremental shuttle walk test (ISWT) and unsupported upper limb exercise test (UULEX) for Portuguese adults.

DESIGN

Cross-sectional study. Descriptive statistics and differences between age decades and genders were explored using univariate general linear models to compute reference values. Reference equations were established with a forward stepwise multiple regression.

SETTING

General community.

PARTICIPANTS

In total, 645 adult volunteers without disabilities [43% male, mean age 55.1 (standard deviation 23.6) years] were recruited from the university campus and surrounding community.

INTERVENTION

Not applicable.

MAIN OUTCOME MEASURES

Data on age, gender, height, weight, body mass index and smoking status were collected using a structured questionnaire. Physical activity was evaluated using the Brief Physical Activity Assessment Tool. Participants performed two repetitions of the 6MWT, ISWT and UULEX, and the best repetition was used for analysis.

RESULTS

Overall, performance was better in males than in females, and decreased with age. Participants' performance was significantly reduced after the sixth decade of life compared with the other decades (P<0.001). Reference equations were: 6MWT=226.93-(5.00×age)+(360.41×height), R²=71%; ISWT=393.81-(17.98×age)+(185.64×gender)+(775.88×height), R²=83%; and UULEX=16.71-(0.14×age)+(2.66×gender), R²=57%.

CONCLUSION

Leg or arm exercise field tests are affected significantly by age and gender. These results will aid health professionals to interpret the results of field tests obtained from healthy or diseased adult populations.

The impacts of parity on lung function data (LFD) of healthy females aged 40 years and more issued from an upper middle income country (Algeria): A comparative study

BACKGROUND

Studies evaluating the impacts of parity on LFD of healthy females presented controversial conclusions.

AIM

To compare the LFD of healthy females broken down according to their parities.

METHODS

A medical questionnaire was administered and anthropometric data were determined. Two groups [G1 (n = 34): ≤ 6; G2 (n = 32): > 6] and three classes [C1 (n = 15): 1-4; C2 (n = 28): 5-8; C3 (n = 23): 9-14] of parities were identified. LFD (plethysmography, specific airway resistance (sRaw)] were determined. Student's t-test and ANOVA test with post-Hoc test were used to compare the two groups' and the three classes' data.

RESULTS

G1 and G2 were age and height matched; however, compared to G1, G2 had a lower body mass index (BMI). C1, C2 and C3 were height, weight and BMI matched; however, compared to C2, C3 was older. G1 and G2 had similar values of FEV1, forced- and slow- vital capacities (FVC, SVC), maximal mid-expiratory flow (MMEF), forced expiratory flow at x% of FVC (FEFx%), peak expiratory flow (PEF), expiratory and inspiratory reserve volumes (ERV, IRV, respectively), inspiratory capacity (IC), sRaw, FEV1/FVC, FEV1/SVC, and residual volume/total lung capacity (RV/TLC). The three classes had similar values of MMEF, FEFx%, PEF, thoracic gas volume (TGV), ERV, IRV, FEV1/FVC, FEV1/SVC and RV/TLC. Compared to G1, G2 had higher TGV (2.68±0.43 vs. 3.00±0.47 L), RV (1.80±0.29 vs. 2.04±0.33 L) and TLC (4.77±0.62 vs. 5.11±0.67 L). Compared to C1, C2 had higher FEV1 (2.14±0.56 vs. 2.47±0.33 L), FVC (2.72±0.65 vs. 3.19±0.41 L), SVC (2.74±0.61 vs. 3.24±0.41 L), TLC (4.47±0.59 vs. 5.10±0.58 L), IC (1.92±0.41 vs. 2.34±0.39 L) and sRaw (4.70±1.32 vs. 5.75±1.18 kPa*s). Compared to C1, C3 had higher TLC (4.47±0.59 vs. 5.05±0.68 L) and RV (1.75±0.29 vs. 2.04±0.30 L).

CONCLUSION

Increasing parity induced a tendency towards lung-hyperinflation.

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

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

Reference equations for the 6-minute walk distance in healthy Portuguese subjects 18-70 years old

INTRODUCTION

Six-minute walk test (6MWT) is used for evaluating functional exercise capacity. To the best of our knowledge, there are no reference equations to predict six-minute walk distance (6MWD) for the Portuguese population. The aims of the present study were to measure anthropometric data and 6MWD in a sample of healthy Portuguese population, to establish reference equations to predict 6MWD and to compare our equations with those obtained by previously published studies.

METHODS

We conducted an observational prospective study. We consecutively recruited 158 healthy 18-70 years old subjects from Porto district, who performed two 6MWTs using a standardized protocol. The best 6MWD was used for further analysis.

RESULTS

The mean 6MWD was 627.8m (SD=73.3m). The variables that were significantly associated with the 6MWD were age, sex, BMI and ΔHR (Heart Rate_{at the end of the test}-HR_{at rest)}. We found three explanatory models for 6MWD, the best with an explanatory power of 38%: 6MWD=721.7-1.6×Age-4.0×BMI+0.9×ΔHR+58.4×Sex. We verified that 6MWD decreased 1.6m per year of age, and 4.0m per unit of BMI and increased 0.892m per beat per minute. Moreover, on average, males walk 58.4m more than females (p<0.001). Applying equations from other studies to our population resulted in an overestimation or underestimation of the 6MWD.

CONCLUSION

The present study was the first to describe the 6MWD in healthy Portuguese people aged 18-70 years old and to propose predictive equations. These can contribute to improving the evaluation of Caucasian Mediterranean patients with diseases that affect their functional capacity.

Sarcopenia, nutritional status and functionality in elderly women living in the community

Abstract Objective: to evaluate the relationship between sarcopenia, functional capacity and nutritional status among elderly women living in the community. Method: an observational, cross-sectional study was performed with 100 elderly women aged over 60 years. A questionnaire containing identification and socioeconomic data and information relating to the practice of physical activity was applied, while anthropometric and body composition data were measured through bioimpedance and functionality data was assessed using the six-minute walk test (6MWT). Independent t-tests were performed for the quantitative variables and analysis of variance (ANOVA) was used to compare the means of the variables. Multiple linear regression analyzes were performed to estimate the mean 6MWTfor each of the variables studied. Results: The average age of the elderly women was 67 (± 8.0) years, 41% practiced physical activity, 38% had at least an elementary school education, 48% received up to two minimum wages and 91% were obese according to waist circumference (WC). The prevalence rates for the presence of sarcopenia were: 5% for sarcopenic obesity (SO), 63% for obesity, 14% for sarcopenia and 18% had adequate weight. Elderly women who practiced physical activity, had at least an elementary education and who were non-obese according to WC, performed better in the 6MWT. There were no significant differences in the 6MWTbased on income or Body Mass Index (p>0.05). Non-obese and non-sarcopenic women walked further in the functional test than the other women (p = 0.021). Conclusion: SO was present in 5% of the elderly women and is related to poor physical performance, which was also present in elderly women with sarcopenia and obesity.

Walk performance in Thai men and women: physical activity dependence

Background: Six-minute walk test (6MWT) is a measure of functional capacity and a predictor of morbidity and mortality in the elderly. Published reference equations for the six-minute walk distance (6MWD) were derived from healthy subjects with sufficient physical activity, and may not be valid for patients with limited physical activity. Objective: To measure 6MWD in healthy individuals with sufficient (Suff) and insufficient (Insuff) levels of physical activity in Thai, and to compare the measured 6MWD with those calculated using published reference equations. Methods: Healthy volunteers aged 45-65 years (77 men and 85 women) performed three standard 6MWT. Physical activity levels were determined using a one-week recall physical activity questionnaire. The subjects were classified as having sufficient or insufficient levels of physical activity. Results: 6MWD of the Suff group was greater than the Insuff group in both men (701+89 m vs. 652+55 m, p = 0.005) and women (619+49 m vs. 571+35 m, p <0.001). The predicted 6MWD from published reference equations underestimated the measured 6MWD of men in Suff group, while it overestimated the measured 6MWD of women in Insuff group. Conclusion: Level of physical activity affected 6MWD of the subjects. Published references must be carefully applied for predicting 6MWD of individuals with various levels of physical activity.

Reference equations for the six-minute walk distance in the healthy Chinese population aged 18-59 years

BACKGROUND

The six-minute walk test (6MWT) is a safe, simple, inexpensive tool for evaluating the functional exercise capacity of patients with chronic respiratory disease. However, there is a lack of standard reference equations for the six-minute walk distance (6MWD) in the healthy Chinese population aged 18-59 years.

AIMS

The purposes of the present study were as follows: 1) to measure the anthropometric data and walking distance of a sample of healthy Chinese Han people aged 18-59 years; 2) to construct reference equations for the 6MWD; 3) to compare the measured 6MWD with previously published equations.

METHOD

The anthropometric data, demographic information, lung function, and walking distance of Chinese adults aged 18-59 years were prospectively measured using a standardized protocol. We obtained verbal consent from all the subjects before the test, and the study design was approved by the ethics committee of Wenzhou People's Hospital. The 6MWT was performed twice, and the longer distance was used for further analysis.

RESULTS

A total of 643 subjects (319 females and 324 males) completed the 6MWT, and average walking distance was 601.6±55.51 m. The walking distance was compared between females and males (578±49.85 m vs. 623±52.53 m; p < 0.0001) and between physically active subjects and sedentary subjects (609.3±56.17 m vs. 592±53.23 m; p < 0.0001). Pearson's correlation indicated that the 6MWD was significantly correlated with various demographic and the 6MWT variables, such as age, height, weight, body mass index (BMI), heart rate after the test and the difference in the heart rate before and after the test. Stepwise multiple regression analysis showed that age and height were independent predictors associated with the 6MWD. The reference equations from white, Canadian and Chilean populations tended to overestimate the walking distance in our subjects, while Brazilian and Arabian equations tended to underestimate the walking distance. There was no significant difference in the walking distance between Korean reference equations and the results of the current study.

CONCLUSION

In summary, age and height were the most significant predictors of the 6MWD, and regression equations could explain approximately 34% and 28% of the distance variance in the female and male groups, respectively.

Self-reported physical activity versus physical function capacity: alternatives for energy expenditure estimation

The extent to which self-report activity measured by the International Physical Activity Questionnaire (IPAQ) can substitute performance-based functional capacity measured by the Six-Minute Walk Test (6MWT) remains inconclusive. This study assessed Physical Activity (PA) and Functional Exercise Capacity (FEC); and also determined the relationship between PA and FEC in apparently healthy young adults. A total of 342 (145 males and 197 females) undergraduates of Obafemi Awolowo University, Ile-Ile, Nigeria participated in the study. The IPAQ was used to assess PA, while FEC was assessed using the 6MWT, and expressed in terms of the Six-Minute Walk Distance (6MWD), Six-Minute Walk Work (6MWW), Maximum Oxygen Uptake (VO2max) and Metabolic Equivalent (METS). Anthropometric and cardiovascular parameters were measured following standardized procedures. Data was analyzed using descriptive and inferential statistics. The alpha level was set at 0.05. The mean age of the participants was 22.0±2.87 years. The mean IPAQ score of all participants was 1471.4±1086.93. The percentage for low, moderate and high PA was 19% (65), 41.2% (141) and 39.8% (136), respectively. The mean 6MWD, 6MWW, VO2max and METS were 639.47 ±66.6 m, 41805.0 ±8520.6 kg·m, 28.9 ±1.92 mlO2k-1min-1, 4.05 ±0.32 mL/kg, respectively. There were signifi cant positive correlations between PA and each of the 6MWD (r=0.268; p=0.001), 6MWW (r=0.219; p=0.001), VO2max (r=0.268; p=0.001), METS (r=0.268; p=0.001). Measures of exercise capacity were not signifi cantly correlated with the anthropometric variables (p>0.05). Self-report of physical activity in healthy young adults does not adequately substitute the results of the Six-Minute Walk Test. Mbada Ch.E., Osifeso T.A., Johnson O.E., Okonji A.M., Odeyemi E.A. Self-reported physical activity versus physical function capacity: alternatives for energy expenditure estimation. Med Rehabil 2016; 20(4): 4-12. DOI: 10.5604/01.3001.0009.5479 null

[Sub-maximal aerobic capacity and quality of life of patients with rheumatoid arthritis]

BACKGROUND

Studies about sub-maximal aerobic capacity of patients with rheumatoid arthritis are scarce.

AIMS

To assess the sub-maximal aerobic capacity of these patients through the 6-min walk test, estimated age of the "muscular and cardiorespiratory" chain.

METHODS

Thirty-seven consecutive patients (aged 20 to 60 years) with newly diagnosed rheumatoid arthritis will be included. Non-inclusion criteria will be: use of drugs (e.g.; methotrexate, beta-blockers), orthopaedic or rheumatologic conditions (other than rheumatoid arthritis) that may alter walking ability and recent infections. Exclusion criteria will be: 6-min walking test contra-indications and imperfect performance of the required lung function and walking maneuvers. Signs of walking intolerance will be: test interruption, distance ≤lower limit of normal, dyspnea score ≥5/10 (visual analogue scale) at the end of the test, haemoglobin oxygen saturation (SpO₂) drop ≥5%, cardiac frequency at the end of the test ≤60% of maximum predicted. An estimated "muscular and cardiorespiratory chain" age higher than the chronological one will be considered as a sign of accelerated ageing.

EXPECTED RESULTS

A high percentage of patients suffering from rheumatoid arthritis would show evidences of walking limitation and accelerated "muscular and cardiorespiratory chain" ageing. There would be a significant correlation between the walking test and clinical, biological, radiological and pulmonary function data and the patients' quality-of-life status.

Reference Equation for Six Minute Walk Test in Healthy Western India Population

INTRODUCTION

The Six Minute Walk Test (6MWT) is used to assess disease progression and survival in chronic cardiopulmonary disorders. However, variability is noted in the six minute walk test distance (6MWD) in different populations.

AIM

We aimed to develop a reference equation for 6MWD in healthy Western India population and compare the results with previously published Indian and Caucasian reference equations.

MATERIALS AND METHODS

Total 174 healthy subjects between 25 to 75 years performed the 6MWT. Variables assessed were age, height, weight, body mass index and sex. Predicted equations were derived using multiple linear regression and compared with the equations for North Indian male, South Indian and Caucasian population using Bland - Altman method.

RESULTS

The 6MWD mean (SD) was 512.38 (67.84) m for men and 457.27 (56.75) m for women with p=0.001. The 6MWD correlated with age (r=-0.44), height (r=0.43), weight (r=0.21) in univariate analysis. Stepwise multiple regression analysis showed age and sex to be independent predictors of 6MWD, R(2) =0.307. The reference equation for healthy Western India population is 553.289 + (-2.11 x age) + (45.323 x sex; men=1 and women =0). Bland Altman analysis showed that the mean bias was 50.87m (95% limits of agreement 134.77 to - 33.0) for North Indian male equation, 50.75m (95% limits of agreement 105.72 to - 4.22) for South Indian equation and 122.72m (95%limits of agreement 254.11 to - 8.67) for Enright and Sherrill's equation.

CONCLUSIONS

The North Indian male, South Indian and Caucasian equations significantly over-estimated the predicted walk distance for our healthy population. Hence, there is a need to develop subgroup population specific reference equations.

Six-Minute Walking Test: Normal Reference Values for Taiwanese Children and Adolescents

BACKGROUND

The 6-minute walking test (6MWT) is a simple method used to evaluate exercise capacity in adults and children with cardiac diseases. Normal reference values in pediatric populations have been reported, but significant variations in the walking distance (6MWD) were noted among different studies. We aimed to provide and validate normal reference values of the 6MWD for healthy Taiwanese pediatric population between 7 and 17 years of age.

METHODS

Healthy children and adolescents were recruited from 13 randomly selected schools in Kaohsiung City. From that recruitment effort, 762 participants (50.1% male) were included, and the 6MWT was conducted using standardized protocols. The main outcome measure utilized was the 6MWD, which was used to construct centile charts and Z score equations. Data from additional 64 healthy volunteers recruited from the National Taiwan University Children's Hospital were used to validate these standards.

RESULTS

There was an overall linear trend of increase in the 6MWD between 7 and 17 years of age (p < 0.001). Males covered significantly more distance than females after the age of 14 years, when the 6MWD essentially plateaued in female adolescents. Upon multivariate analysis, height was the most significant positive predictor of the 6MWD, while body mass index negatively correlated with the 6MWD. The height-based normal reference values of the 6MWD, derived from the 6MWT conducted in the school settings, were validated by a second cohort who received 6MWT inside the hospital.

CONCLUSIONS

Normal reference values of the 6MWD in healthy Taiwanese children and adolescents may serve as useful references for future clinical and research studies.

KEY WORDS

Adolescents; Children; Six-minute walking test; Taiwan.

Defining obstructive ventilatory defect in 2015

INTRODUCTION

There is no clear consensus as to what constitutes an obstructive ventilatory defect (OVD): Is it FEV1/FVC

AIM

To determine, according to the two definitions, the percentage of subjects having an OVD among them explored in a lung function exploration laboratory.

POPULATION AND METHODS

This is a retrospective study including 4,730 subjects aged 17-85 years. Subjects were divided according to the presence [physio (+) or operat (+)] or absence [physio (-) or operat (-)] of an OVD, and into younger (<45 years, n=2,076), older (≥45 years, n=2,654), smokers (n=1,208), and non-smokers (n=3,522) groups.

RESULTS

For the total sample, the younger and older groups [mean±SD of age (years), respectively, 46.7±14.1; 33.9±7.4, and 56.8±9.1], the 'physiological definition' detected, respectively, 13.46, 43.22, and 5.09% more OVD than the 'operational one' (p<0.05). In addition, the operational definition, compared with the physiological one, overdiagnosed OVD in 2.33 and 0.44% of smokers and non-smokers, respectively, and underdiagnosed it in 4.46% and 29.72% of smokers and non-smokers, respectively (p<0.05). Compared with the group 'physio (-), operat (+)', the 'physio (+), operat (-)' one was younger (74.2±4.7 years vs. 40.9±10.3 years) and had significantly higher FEV1 (62±13% vs. 78±17%) and FVC (71±15% vs. 93±19%).

CONCLUSION

The frequency of OVD much depends on the criteria used for its definition.

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Key Words

• FEV1/FVC
• fixed threshold
• guideline
• lower limit of normal
• obstructive ventilatory defect
• spirometry

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MESH Headings

• Adolescent
• Adult
• Aged
• Aged, 80 and over
• Female
• Forced Expiratory Volume
• Humans
• Male
• Middle Aged
• Pulmonary Disease, Chronic Obstructive/diagnosis
• Pulmonary Disease, Chronic Obstructive/epidemiology
• Pulmonary Disease, Chronic Obstructive/physiopathology
• Respiratory Function Tests
• Retrospective Studies
• Smoking/adverse effects
• Smoking/physiopathology
• Spirometry/methods
• Tunisia/epidemiology
• Vital Capacity

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Affiliation(s)

Zied Affes Department of Physiology and Functional Exploration, Farhat HACHED University Hospital of Sousse, Sousse, Tunisia
Salaheddine Rekik Department of Physiology and Functional Exploration, Farhat HACHED University Hospital of Sousse, Sousse, Tunisia
Helmi Ben Saad Department of Physiology and Functional Exploration, Farhat HACHED University Hospital of Sousse, Sousse, Tunisia Laboratory of Physiology, Faculty of Medicine of Sousse, University of Sousse, Sousse, Tunisia Research Laboratory N° LR14ES05: Interactions of the Cardiopulmonary System, Faculty of Medicine of Sousse, University of Sousse, Sousse, Tunisia;

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An Evaluation of Prediction Equations for the 6 Minute Walk Test in Healthy European Adults Aged 50-85 Years

OBJECTIVE

This study compared actual 6 minute walk test (6MWT) performance with predicted 6MWT using previously validated equations and then determined whether allometric modelling offers a sounder alternative to estimating 6MWT in adults aged 50-80 years.

METHODS

We compared actual 6MWT performance against predicted 6MWT in 125 adults aged 50-85 years (62 male, 63 female). In a second sample of 246 adults aged 50-85 years (74 male, 172 female), a new prediction equation for 6MWT performance was developed using allometric modelling. This equation was then cross validated using the same sample that the other prediction equations were compared with.

RESULTS

Significant relationships were evident between 6MWT actual and 6MWT predicted using all of the commonly available prediction equations (all P<0.05 or better) with the exception of the Alameri et al prediction equation (P>0.05). A series of paired t-tests indicated significant differences between 6MWT actual and 6MWT predicted for all available prediction equations (all P<0.05 or better) with the exception of the Iwama et al equation (P = .540). The Iwama et al equation also had similar bias (79.8m) and a coefficient of variation of over 15%. Using sample 2, a log-linear model significantly predicted 6MWT from the log of body mass and height and age (P = 0.001, adjusted R2 = .526), predicting 52.6% of the variance in actual 6MWT. When this allometric equation was applied to the original sample, the relationship between 6MWT actual and 6MWT predicted was in excess of values reported for the other previously validated prediction equations (r = .706, P = 0.001). There was a significant difference between actual 6MWT and 6MWT predicted using this new equation (P = 0.001) but the bias, standard deviation of differences and coefficient of variation were all less than for the other equations.

CONCLUSIONS

Where actual assessment of the 6MWT is not possible, the allometrically derived equation presented in the current study, offers a viable alternative which has been cross validated and has the least SD of differences and smallest coefficient of variation compared to any of the previously validated equations for the 6MWT.

6-Min walk-test data in severe obstructive-sleep-apnea-hypopnea-syndrome (OSAHS) under continuous-positive-airway-pressure (CPAP) treatment

INTRODUCTION

Few studies have evaluated the functional capacity of severe OSAHS.

AIMS

To assess their functional capacity, identify their 6-min walking-distance (6MWD) influencing factors and compare their data with those of two control-groups.

METHODS

Sixty (42 males) clinically consecutive stable patients with severe OSAHS under CPAP were included. Clinical, Epworth questionnaire, anthropometric, polysomnographic, plethysmographic and 6-min walk-test (6MWT) data were collected. Univariate and multivariate analyses were used to identify the 6MWD influencing factors. Data of a subgroup of severe OSAHS aged ≥40 Yrs (n = 49) were compared with those of non-obese (n = 174) and obese (n = 55) groups.

RESULTS

The means ± SD of age and apnea-hypopnea-index were, respectively, 49 ± 10 Yr and 62 ± 18/h. The profile of OSAHS patients carrying the 6MWT, was as follows: at the end of the 6MWT, 31% and 25% had, respectively, a high dyspnea (>5/10, visual analogue scale) and a low heart-rate (<60% of-maximal-predicted), 13% had an abnormal 6MWD (<lower-limit-of-normal), 13% had an oxy-hemoglobin saturation (oxy-sat) fall> 5 points and 3% stopped the walk. The factors that significantly influenced the 6MWD, explaining 80% of its variability, are included in the following equation: 6MWD (m) = 29.66 × first-second-forced-expiratory-volume (L) - 4.19 × Body-mass-index (kg/m(2)) - 51.89 × arterial-hypertension (0. No; 1. Yes) + 263.53 × Height (m) + 2.63 × average oxy-sat during sleep (%) - 51.06 × Diuretic-use (0. No; 1. Yes) - 20.68 × Dyspnea (NYHA) (0. No; 1. Yes) - 38.09 × Anemia (0. No; 1. Yes) + 5.79 × Resting oxy-sat (%) - 586.25. Compared with non-obese and obese groups, the subgroup of OSAHS has a significantly lower 6MWD [100 ± 9%, 100 ± 8% and 83 ± 12%, respectively).

CONCLUSION

Severe OSAHS may play a role in reducing the functional capacity.

Six-minute walk distance in patients with chronic obstructive pulmonary disease: Which reference equations should we use?

The use of different 6-min walk distance (6MWD) reference equations probably results in different predicted 6MWD reference values. We wished to investigate the impact of several 6MWD reference equations for adults in patients with chronic obstructive pulmonary disease (COPD) and factors accountable for different 6MWD% predicted values. Twenty-two 6MWD reference equations were applied to a data set of 2757 patients with COPD. The predicted 6MWD reference value of Troosters and colleagues was used as the point of reference. Four out of 21 remaining equations resulted in comparable 6MWD% predicted, 16 equations resulted in significantly higher 6MWD% predicted and 1 equation resulted in a significantly lower 6MWD% predicted. Similar differences in 6MWD% predicted were observed after stratification by sex. Body mass index and global initiative for chronic obstructive lung disease (GOLD) stage classification demonstrated varying results within and between the groups; 9 out of 21 equations resulted in comparable 6MWD% predicted in underweight patients but only 1 equation demonstrated comparable result in obese. Eight equations in GOLD I, whilst 5 out of 21 equations in GOLD IV resulted in comparable 6MWD% predicted. Existing 6MWD reference equations will give varying results. The choice of 6MWD reference equation should consider the consistency of 6-min walk test operating procedures and at least be specific for the country/region of origin.

Reference values for standardized tests of walking speed and distance: a systematic review

OBJECTIVE

To provide an overview of the reference values and methodology used to obtain them for time- and distance-limited walk tests.

METHODS

We performed a systematic review and searched PubMed, MEDLINE (Ovid), EMBASE, CINAHL, Scopus, PEDro, and The Cochrane Library from 1946 to May 2013. Full-text peer-reviewed articles written in English, French or Spanish were considered eligible. Two authors independently screened titles and abstracts. One author determined eligibility of full-text articles, appraised methodological quality, and extracted data. A second author independently verified the accuracy of extracted data.

RESULTS

Of the 41 eligible studies reviewed, 25 failed to describe the method used to select participants and 10 had an inadequate sample size. Twenty-five studies provided reference values for one time-limited walk test (6-min walk test (6 MWT)) and 18 studies provided reference values for 15 distance-limited walk tests. Across studies, walk test distances ranged from 3m to 40m. Descriptive values and reference equations for the 6 MWT were reported in 15 and 20 studies, respectively. Across 43 regression equations (median R(2)=0.46), age (98%) and sex (91%) were most frequently included. The equation yielding the maximum R(2) value (0.78) included age, height, weight and percentage of predicted maximum heart rate. Among six unique regression equations for distance-limited walk tests (median R(2)=0.17), sex (83%), age (67%) and weight (67%) were most frequently included. The equation yielding the maximum R(2) value (0.25) included age and sex.

CONCLUSIONS

Reference values reported for these tests provide a basis for classifying walking capacity as within normal limits, determining the magnitude of deficit, educating clients, setting rehabilitation goals, and planning studies.