The six-minute walking test (6MWT) is an essential test for evaluating exercise tolerance in many respiratory and cardiovascular diseases. Frailty and sarcopenia can cause rapid aging of the cardiovascular system in elderly people. Early detection and evaluation of frailty and sarcopenia are crucial for determining the treatment method. We aimed to develop a wearable measuring system for the 6MWT and propose a method for identifying frailty and quantifying walking muscle strength (WMS). In this study, 60 elderly participants were asked to wear accelerometers behind their left and right ankles during the 6MWT. The gait data were collected by a computer or smartphone. We proposed a method for analyzing walking performance using the stride length (SL) and step cadence (SC) instead of gait speed directly. Four regions (Range I-IV) were divided by cutoff values of SC = 2.0 [step/s] and SL = 0.6 [m/step] for a quick view of the frail state. There were 62.5% of frail individuals distributed in Range III and 72.4% of non-frail individuals in Range I. A concept of a WMS score was proposed for estimating WMS quantitatively. We found that 62.5% of frail individuals were scored as WMS1 and 41.4% of the non-frail elderly as WMS4. The average walking distances corresponding to WMS1-4 were 207 m, 370 m, 432 m, and 462 m, respectively. The WMS score may be a useful tool for quantitatively estimating sarcopenia or frailty due to reduced cardiopulmonary function.

Heart failure (HF) patients traditionally report dyspnoea as their main symptom. Although the cardiopulmonary exercise test (CPET) and 6 min walking test are the standardized tools in assessing functional capacity, neither cycle ergometers nor treadmill maximal efforts do fully represent the actual HF patients\' everyday activities [activities of daily living (ADLs)] (i.e. climbing the stairs). New-generation portable metabolimeters allow the clinician to measure task-related oxygen intake (VO2) in different scenarios and exercise protocols. In the last years, we have made considerable progress in understanding the ventilatory and metabolic behaviours of HF patients and healthy subjects during tasks aimed to reproduce ADLs. In this paper, we describe the most recent findings in the field, with special attention to the relationship between the metabolic variables obtained during ADLs and CPET parameters (i.e. peak VO2), demonstrating, for example, how exercises traditionally thought to be undemanding, such as a walk, instead represent supramaximal efforts, particularly for subjects with advanced HF and/or artificial heart (left ventricular assist devices) wearers.
This article summarizes the most recent evidence on the cardiometabolic behaviours of a full spectrum of heart failure (HF) patients of different severity during their daily life activities (i.e. walking, making a bed, and taking the stairs).Heart failure patients experience symptoms (mostly dyspnoea) during daily activities that sometimes represent maximal or supramaximal exercises for them, particularly for the most severe patients.Measuring metabolic parameters (O2 intake, ventilation, and CO2 production) through appropriate devices during these activities provides a better understanding of the pathophysiological mechanisms underlying HF patients’ symptoms and their adaptation. This can lead to the detection of new parameters that can become novel patient-centred prognostic markers or therapeutic targets for drugs and rehabilitation treatments.

BACKGROUND: The aim of this study was to compare energy expenditure (EE) predicted by accelerometery (EEAcc) with indirect calorimetry (EEMETA) in individuals with hemiparesis.
METHODS: Twenty-four participants (12 with stroke and 12 healthy controls) performed a six-minute walk test (6MWT) during which EEMETA was measured using a portable indirect calorimetry system and EEACC was calculated using Bouten\'s equation (1993) with data from a three-axis accelerometer positioned between L3 and L4.
RESULTS: The median EEMETA was 9.85 [8.18;11.89] W·kg-1 in the stroke group and 5.0 [4.56;5.46] W·kg-1 in the control group. The median EEACC was 8.57 [7.86;11.24] W·kg-1 in the control group and 8.2 [7.05;9.56] W·kg-1 in the stroke group. The EEACC and EEMETA were not significantly correlated in either the control (p = 0.8) or the stroke groups (p = 0.06). The Bland-Altman method showed a mean difference of 1.77 ± 3.65 W·kg-1 between the EEACC and EEMETA in the stroke group and -2.08 ± 1.59 W·kg-1 in the controls.
CONCLUSIONS: The accuracy of the predicted EE, based on the accelerometer and the equations proposed by Bouten et al., was low in individuals with hemiparesis and impaired gait. This combination (sensor and Bouten\'s equation) is not yet suitable for use as a stand-alone measure in clinical practice for the evaluation of hemiparetic patients.

Background-Patients affected by Long COVID often report shorter times spent doing physical activity (PA) after COVID-19. The aim of the present study was to evaluate potential associations between PA levels and parameters of physical function in a cohort of COVID-19 survivors with post-acute symptoms, with a particular focus on individuals aged 65 and older. Materials and methods-PA levels before and after COVID-19 were assessed in a sample of patients that had recovered from COVID-19 and were admitted to a post-acute outpatient service at the Fondazione Policlinico Universitario Agostino Gemelli IRCCS (Rome, Italy). Participation in PA was operationalized as the engagement in leisure-time PA for at least 150 min per week in the last 3 months. Self-rated health and measures of physical performance and muscle strength were assessed. Results-Mean age of 1846 participants was 55.2 ± 14.4 years and 47% were women. Before COVID-19, inactivity was detected in 47% of the whole study population; only 28% maintained pre-COVID-19 PA engagement. Inactivity was more frequent in women. The stopping of physical activity was associated with increased BMI and CRP levels, lower vitamin D levels and a higher prevalence of post-COVID-19 fatigue, dyspnea, arthralgia, and myalgia. Active participants had higher handgrip strength and performed better on both the six-minute walking test (6MWT) and at the one-minute sit-to-stand test (1MSTST). In particular, at the 6MWT, participants 65 and older that were still active after COVID-19 walked 32 m more than sedentary peers. Moreover, the distance covered was 28 m more than those who were active only before COVID-19 (p = 0.05). Formerly active subjects performed similarly at the 6MWT to inactive participants. PA was associated with better self-rated health. Conclusions-Our findings reveal that inactivity is frequent in the post-acute COVID-19 phase. Stopping physical activity after COVID-19 results in measures of performance that are comparable to those who were never active. Relevant differences in the distance covered at the 6MWT were found between older active subjects and their sedentary peers.

The incremental prognostic value of the six-minute walking test over conventional risk factors has not been evaluated in an adequate number of patients with heart failure with preserved ejection fraction (HFpEF). Therefore, we aimed to examine its prognostic significance using data from the FRAGILE-HF study.
A total of 513 older patients who were hospitalized for worsening heart failure were examined. Patients were classified according to the tertiles of six-minute walking distance (6MWD): T1 (<166 m), T2 (166-285 m), and T3 (≥285 m). During the 2-year follow-up period after discharge, 90 all-cause deaths occurred. Kaplan-Meier curves showed that the T1 group had significantly higher event rates than the other groups (log-rank p = 0.007). Cox proportional hazard analysis revealed that the T1 group was independently associated with lower survival, even after adjusting for conventional risk factors (T3: hazard ratio 1.79, 95% confidence interval 1.02-3.14, p = 0.042). The addition of the 6MWD to the conventional prognostic model showed a statistically significant incremental prognostic value (net reclassification improvement 0.27, 95% confidence interval 0.04-0.49; p = 0.019).
The 6MWD is associated with survival in patients with HFpEF and has an incremental prognostic value over conventional well-validated risk factors.

Because absolute changes in outcomes are difficult to interpret and the minimal clinically important difference (MCID) is not suitable to address this challenge, a novel method of classifying outcomes by relating changes to baseline values is warranted. We used the \"performance score\" (T2D), which reflects individual performance, enabling us to consider the functional status at the beginning of rehabilitation without dealing with the problems of mathematical coupling or regression effects, as encountered in ANCOVA. To illustrate the T2D, we retrospectively analyzed changes in the six-minute walking test (6MWT) in COPD patients undergoing outpatient pulmonary rehabilitation and compared the results with absolute differences related to a predetermined MCID. We evaluated a total of 575 COPD patients with a mean age of 61.4 ± 9.2 years. 6MWT improved significantly, with a mean change of 32.3 ± 71.2. A total of 105/311 participants who had reached the MCID were still classified as \"below average\" by the T2D. Conversely, 76/264 patients who had not reached the MCID were classified as \"above average\". This new performance measure accounts for the patient\'s current status and for changes over time, potentially representing a simple and user-friendly tool that can be used to quantify a patient\'s performance and response to rehabilitation.

Self-monitoring for spirometry is beneficial to assess the progression of lung disease and the effect of pulmonary rehabilitation. However, home spirometry fails to meet both accuracy and repeatability criteria in a satisfactory manner. The study aimed to propose a pervasive spirometry estimation system with the six-minute walking test (6MWT), where the system with information management, communication protocol, predictive algorithms, and a wrist-worn device, was developed for pulmonary function. A total of 60 subjects suffering from respiratory diseases aged from 25 to 90 were enrolled in the study. Pulmonary function test, walking steps, and physical status were measured before and after performing the 6MWT. The significant variables were extracted to predict per step distance (PSD), forced vital capacity (FVC) and forced expiratory volume in one second (FEV1). These predicted formulas were then implemented in a wrist-worn device of the proposed pervasive estimation system. The predicted models of PSD, and FVC, FEV1 with the 6MWT were created. The estimated difference for PSD was-0.7 ± 9.7 (cm). FVC and FEV1 before performing 6MWT were 0.2 ± 0.6 (L) and 0.1 ± 0.6 (L), respectively, and with a sensitivity (Sn) of 81.8%, a specificity (Sp) of 63.2% for obstructive lung diseases, while FVC and FEV1 after performing the 6MWT were 0.2 ± 0.7 (L) and 0.1 ± 0.6 (L), respectively, with an Sn of 90.9% and an Sp of 63.2% for obstructive lung diseases. Furthermore, the developed wristband prototype of the pulmonary function estimation system was demonstrated to provide effective self-estimation. The proposed system, consisting of hardware, application and algorithms was shown to provide pervasive assessment of the pulmonary function status with the 6MWT. This is a potential tool for self-estimation on FVC and FEV1 for those who cannot conduct home-based spirometry.

BACKGROUND: There is scarce information about middle-term evolution of hospitalized patients who suffer from pneumonia caused by COVID-19. The objective of this study is to determine the clinical, respiratory, tomographic and functional impact on COVID-19 patients with moderate (MP) to severe (SP) pneumonia after six months of acute infection.
METHODS: Analysis was carried out by MP and SP groups, desaturators during the 6-minute-walking test and the presence of fibrotic like pattern on HRCT. Outcomes at 3 and 6 months were compared.
RESULTS: The analysis included 129 patients, between 57 ± 11 years old. Frequent comorbidities were: arterial hypertension 38.1%, diabetes 30.4%, respiratory 18.6%). Comparing 3 and 6 months, improvement in quality of life was observed in MP and SP. The DP walked less meters in the MWT, worsened life quality and more fibrotic like pattern. The fibrotic pattern was related to the fall of CVF < 80% on MP and SP (p = 0.048 and p = 0.007), and with DP (p = 0.002). On multivariated analysis, the fibrotic like pattern was associated to the reduction of CVF with OR = 4.44 (1.94-10.18, p <0.01) and desaturation OR = 5.01(1.63-15.42, p < 0.01). On this cohort it was observed more functional and tomographic compromise on the DP The fibrotic like pattern was related to worse functional evolution and oximetry.
CONCLUSIONS: Follow-up after discharge of COVID-19 patients with SP, DP or fibrotic changes in HCRT is underlined.
Introducción: Hay información escasa sobre la evolución de los enfermos hospitalizados por neumonía por COVID-19 a mediano plazo. El objetivo de este estudio fue determinar en pacientes con neumonía moderada (NM) o grave (NG) por COVID-19, el impacto clínico, funcional respiratorio y tomográfico a los 6 meses. Métodos: Se realizó análisis según grupos de NM y NG, desaturadores (PD) en la prueba de caminata de 6 minutos y presencia del patrón tomográfico de alta resolución (TACAR) símil fibrótico. Se compararon los resultados a los 3 y 6 meses. Resultados: Se incluyeron 129 pacientes, edad 57 ± 11 años, comorbilidades frecuentes (hipertensión arterial 38.1%, diabetes 30.4% y respiratorias 18.6%). Al comparar 3 y 6 meses se observó mejoría de la calidad de vida en NM y NG. Los PD presentaron menor metraje caminado, peor calidad de vida y mayor presencia de patrón símil fibrótico. Este patrón se relacionó con la caída de la FVC 80% en NM y NG (p = 0.048 y p = 0.007), y con PD (p = 0.002). En el análisis multivariado, el patrón símil fibrótico s e asoció a la reducción de la CVF con OR = 4.44 (1.94-10.18, p <0.01) y a la desaturación, OR = 5.01 (1.63-15.42, p <0.01). En esta cohorte se observó mayor compromiso funcional y tomográfico en los PD. El patrón símil fibrótico se relacionó con peor evolución funcional y oximétrica. Discusión: Es importante el seguimiento de los pacientes con NG, los PD y los que presentan patrón fibrótico al alta de neumonía por COVID-19.

Background: Bariatric surgery is a safe and effective method to lose weight over time. However, some patients fail to achieve healthy weight losses. We aimed to determine if a moderate-intensity physical exercise intervention in patients who underwent bariatric surgery increases their functional capacity thus improving bariatric surgery results. Methods: We conducted a parallel-group non-blinded randomized controlled trial at a surgery clinic in Talca, Chile. A total of 43 participants with obesity and scheduled bariatric surgery completed the six months follow-up. A physical exercise program was conducted in exercise group participants one month after bariatric surgery. Walked distance in the six-minute walk test, BMI, Borg scale of perceptive exertion results and cardiovascular variables were evaluated. Results: Patients’ weight significantly decreased after bariatric surgery but there was no difference between the groups of study. The exercise group progressed from a base value of 550 ± 75 m walked in the six-minute walk test to a sixth-month value of 649.6 ± 68.5 m (p < 0.05), whilst the control group yielded base values of 554.4 ± 35.1 and a sixth-month walked distance of 591.1 ± 75.34 (p > 0.05). Conclusions: Physical exercise in obese patients undergoing bariatric surgery increased functional capacity independently of weight losses resulting from bariatric surgery.

Use of the six-minute walk test has been proposed as a prognostic marker in liver cirrhosis. In the Letter to the Editor presented here, the authors highlight some important points, which were raised after the article was published in the November issue of the World Journal of Hepatology.