Reference values for six-minute walk distance and six-minute walk work in Caucasian adults

Effect of exercise training on modulating the TH17/TREG imbalance in individuals with severe COPD: A randomized controlled trial

BACKGROUND

Chronic obstructive pulmonary disease (COPD) induces an imbalance in T helper (Th) 17/regulatory T (Treg) cells that contributes to of the dysregulation of inflammation. Exercise training can modulate the immune response in healthy subjects.

OBJECTIVE

We aimed to evaluate the effects of exercise training on Th17/Treg responses and the differentiation of Treg phenotypes in individuals with COPD.

METHODS

This randomized controlled trial included 50 individuals with severe or very severe COPD who were allocated to the Exercise or Control groups. The Exercise group underwent eight weeks of aerobic and muscle strength training, whereas the Control group received usual care. The primary outcome was the change in the phenotypic characteristics of Tregs and Th17 profile differentiation in systemic inflammation.

RESULTS

Exercise training increased the frequency of total and activated Tregs and decreased the frequency of Th17 cells in between-group comparisons. Additionally, Th17/Treg responses were moderately correlated with improvements in the six-minute walking test, muscle strength of the upper and lower limbs, and daily life physical activity levels.

CONCLUSION

Exercise training improved functional exercise capacity, muscle strength, and physical fitness, which was associated with a decrease in the Th17 inflammatory response and an increase in Treg cell phenotypes immunosuppressive activity.

Breaking barriers: novel reference equations for the six-minute walk distance and work in obese Chinese adults

BACKGROUND

The six-minute walk test (6MWT) is a key tool for assessing fitness in obese individuals, but existing reference equations for the six-minute walk distance (6MWD) are limited and overlook the six-minute walk work (6MWW), in turn limiting the clinical applicability of the test. This study aims to establish new 6MWD and 6MWW equations to improve our understanding of functional capacity in obese Chinese adults.

METHODS

A cross-sectional study was conducted at Wenzhou People's Hospital from July 2021 to June 2023. Obese Chinese adults (BMI > 30 kg/m²), aged 18-69 years, completed the 6MWT following the ATS/ERS guidelines. Stepwise multiple regression was used to create sex-specific reference equations for the 6MWD and 6MWW.

RESULTS

A total of 309 obese Chinese adults participated in this study, achieving a mean 6MWD of 550.7 ± 45.85 m and a mean 6MWW of 46149.9 ± 6403.58 kg·m. Sex-specific equations for the 6MWD and 6MWW explained a significant portion of the variance in the values (34-61%).

CONCLUSION

The proposed reference equations for the 6MWD and 6MWW increase the accuracy and applicability of functional capacity assessment tests, outperforming existing reference equations. The inclusion of the 6MWW provides a relatively novel metric that integrates metabolic workload and mechanical efficiency, offering unique insights into the functional performance of obese individuals and allowing tailored health interventions.

Development and Comparison of Reference Equations for the Six-Minute Walk Test in Spanish Healthy Adults Aged 45-85 Years

OBJECTIVES

(i) To develop sex-specific reference equations to predict distance walked (6MWD) in the 6-minute walk test (6MWT), in healthy subjects aged 45-85 years, from different geographic areas of Spain; and (ii) to compare developed equations with previously published in a large sample of COPD patients.

METHODS

First, a cross-sectional multicentre sample of randomly selected healthy subjects from 17 Spanish hospitals and universities performed two 6MWT. Linear regression and fractional polynomial modelling were used to develop the equations. Second, the developed equations were applied to 715 COPD patients from Spanish primary care centres and hospitals, and the % predicted 6MWD obtained was compared with previously published equations using Dunnett's multiple comparisons test.

RESULTS

568 healthy subjects were included (51% females, mean (SD) age 62 (11) years), walked a 6MWD of 615 (113) and 557 (93)m in males and females, respectively. The developed equations included age, weight and height, and explained 43% and 51% of the 6MWD variance for males and females, respectively. In the COPD sample (n=715, 14% females, 68 (9) years, FEV1 61 (18) % predicted, 6MWD 464 (97)m), only 1 out of 9 previously published equations for males, and 6 out of 9 for females predicted 6MWD values similar to those of the newly developed Spanish reference equations.

CONCLUSIONS

The newly developed reference equations provide a more valid prediction of 6MWD in Spanish adults with COPD compared to previously published equations. We suggest their use in future research and clinical practice for the Spanish adult population.

Efficacy of a student-led interprofessional health clinic in regional Australia for preventing and managing chronic disease

Increasing chronic disease rates in regional Australian communities necessitates innovative models of healthcare. We evaluated the efficacy of an interprofessional chronic disease program, delivered within a regional student-led nursing and allied health clinic in Southern Queensland, Australia. Changes to anthropometric, aerobic fitness and strength, and quality of life outcomes were examined at four time points spanning 16 months: intake, program transition (4 months), 6 and 12 months (post-transition). Our primary aim was to investigate whether the health improvements achieved during the program were sustained at 12 months in a subset of participants who provided complete data. Significant improvements were found in 6 of 11 measures, including the 6-minute walk test, grip strength, and self-reported quality of life across physical and psychosocial dimensions, with these improvements maintained to final review. No significant changes were found in body mass index (BMI), waist circumference, fat mass, or muscle mass. This is the first health clinic in regional Australia to deliver a student-led model of interprofessional and collaborative service to tackle the increasing burden of chronic disease in the community. The cost-effectiveness of this service and other potential clinical and social benefits remain to be investigated.

The modified Borg/6-min walk distance ratio: a method to assess exertional breathlessness and leg discomfort using the 6-min walk test

Background

The 6-min walk test (6MWT) is widely used to assess exercise capacity across chronic health conditions, but is currently not useful to assess symptoms, as the scores do not account for the 6-min walk distance (6MWD). We aimed to 1) develop normative reference equations for breathlessness and leg discomfort intensity expressed as modified Borg (mBorg)/6MWD ratios; and 2) validate the equations in people with COPD.

Methods

Analysis of people aged ≥40 years who performed two 6MWTs (on a 20-m course) in the Canadian Cohort Obstructive Lung Disease (CanCOLD) study: a healthy cohort (n=291; mean±sd age 67.5±9.4 years; 54% male) with normal 6MWD and lung function, and a COPD cohort (n=156; age 66.2±9.0 years; 56% male; forced expiratory volume in 1 s (FEV1)/forced vital capacity 56.6±8.2%; FEV1 74.4±18.6% pred). The mBorg score was calculated as the Borg 0-10 category ratio intensity rating of breathlessness or leg discomfort recorded at the end of the 6MWT +1 (range 1-11), to avoid zeros and yield ratios proportional to the symptom score and 6MWD-1.

Results

Using data from the healthy cohort, sex-specific normative reference equations for breathlessness and leg discomfort mBorg/6MWD ratios were developed using multivariable linear regression, accounting for age, and body mass or body mass index. In the COPD cohort, abnormal breathlessness and leg discomfort (mBorg/6MWD>upper limit of normal) showed strong concurrent validity with worse airflow limitation, Medical Research Council breathlessness and COPD Assessment Test scores.

Conclusion

Normative references for the mBorg/6MWD ratio are presented to assess breathlessness and leg discomfort responses to the 6MWT in COPD.