Could peak oxygen uptake be estimated from proposed equations based on the six-minute walk test in chronic heart failure subjects?

An Equation With Clinical Applicability and Adequate Validity to Predict the Maximum Oxygen Consumption of Individuals Post-stroke

OBJECTIVE

To develop an equation with clinical applicability and adequate validity to predict the maximum oxygen consumption (V̇o_2max) of individuals post-stroke.

DESIGN

A cross-sectional study.

SETTING

A university laboratory.

PARTICIPANTS

Individuals post-stroke in the chronic phase (at least 6 months post-stroke). Step-1 (equation development): n=50, aged 55±12 years; Step-2 (validity investigation): n=20, aged 58±8 years (N=50 [step 1], N=20 [step 2]).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURE(S)

Step-1 (equation development): multiple linear regression analysis was performed.

DEPENDENT VARIABLE

V̇o_2max (mL/kg^/min) in the cardiopulmonary exercise test.

INDEPENDENT VARIABLES

age (years), sex (1-women, 2-men), body mass index (BMI) (kg/m²), and distance (meters) in the Six-Minute Walk Test (6MWT) (6MWT-Equation) or in the Incremental Shuttle Walk Test (ISWT) (ISWT-Equation). Step-2 (validity investigation): agreement between the V̇o_2max measured and predicted was evaluated with the intraclass correlation coefficient (ICC) with 95% confidence interval (CI) and the Bland-Altman method (α=5%).

RESULTS

In step-1 (equation development), the 4 independent variables for each equation were retained (6MWT-Equation: R²=0.68, P<.001; ISWT-Equation: R²=0.58, P<.001). In step-2 (validity investigation), the 6MWT-Equation showed an ICC of 0.73 (95% CI=0.30, 0.89; P=.004) and a mean bias of 0.003 mL/kg/min; and the ISWT-Equation showed an imprecise ICC of 0.55 (95% CI=-0.12, 0.82; P=.045) and a mean bias of 0.971 mL/kg/min. 6MWT-Equation (V̇o_2max=22.239+0.02 × distance in the 6MWT+4.039 × sex-0.157 × age-0.265 × BMI) showed adequate validity.

CONCLUSIONS

An equation with clinical applicability and adequate validity in the investigated sample was developed to predict the V̇o_2max of individuals post-stroke in the chronic phase (6MWT-Equation). Future studies with larger sample should investigate its external validity.

The prospects for NT-pro BNP level determining in physical activity conditions in patients during the rehabilitation period after the myocardial infarction, complicated with decompensated heart failure

The aim of the study was to determine the futility of NT-pro BNP level analysis during dosed physical exercise for diagnosing decompensated HF in the postinfarction period and the possibility to determine the HF functional class. Materials and methods. 160 patients with previous MI were examined, patients’ average age was (56.67±5.72) years. The patients were randomized in 2 groups dependently on the presence of the signs of II А-B according to V. Kh. Vasylenko and M. D. Strazhesko classification and FC III-IV (according to NYHA) decompensated chronic HF. Group I consisted of 120 patients with Q-QS and non-Q MI; group II (the control one) had 40 patients with MI without signs of decompensated HF; 20 healthy people made up a norm group. Results. Signs of coronary insufficiency such as dizziness and signs of poor peripheral perfusion (cyanosis/paleness) occurred in 104 (86.7 %) and 79 (65.8 %) cases that differ from the same values in the second group 4 (10.0 %) and 14 (35.0 %) respectively. 88 (73.3 %) patients with the signs of decompensated HF felt general weakness, fatigue, and expressed a request to stop the test. The HR in the postinfarction patients with the signs of decompensated HF was before the exercise (88.2±3.18) bpm (p≤0.05); in the patients with past MI without the signs of decompensated HF, it was (75.32±3.41) bpm (p≤0.05); and in the practically healthy people, it was (77.73±3.02) bpm. We found out a reverse moderate correlation between the distances that had been covered by a patient during the 6MWT NT-proBNP level in blood serum of examined patients. Conclusions. Inadequate response to dosed physical exercises and increased immunological parameters as quantitative HF markers could be useful not only for diagnostics, but also for the risk stratification for decompensated HF that had occurred in patients on different rehabilitation stages after an acute MI.

Using the 6-min Walk Test to Monitor Peak Oxygen Uptake Response to Cardiac Rehabilitation in Patients With Heart Failure

Supplemental Digital Content is Available in the Text.

Estimated peak oxygen uptake (V˙o2peak) using 6-min Walk Test distance demonstrated poor agreement with measured V˙o2peak from a cardiopulmonary exercise test in patients with heart failure enrolled in cardiac rehabilitation.

Purpose:

We examined the agreement between peak oxygen uptake (V˙o2peak), estimated using prediction equations from the 6-min Walk Test (6MWT), and V˙o2peak measured using a cardiopulmonary exercise test (CPX) to estimate change in V˙o2peak in patients with heart failure (HF) enrolled in cardiac rehabilitation (CR).

Methods:

This was secondary analysis of 54 (including 9 women) patients with HF who completed a clinical CR program. Four previously published equations using 6MWT distance were used to estimate V˙o2peak and were compared with a CPX at baseline, follow-up, and change using the standard and modified Bland-Altman method. Analyses were repeated for quartiles of cardiorespiratory fitness (CRF) based on measured V˙o2peak from the CPX.

Results:

Bland-Altman plots revealed proportional bias between all prediction equations and the measured V˙o2peak. The difference between methods varied by the level of CRF, with overestimation of prediction equations at greater levels of CRF and underestimation at lower levels of CRF. This poor agreement remained when comparisons were made between the estimated and measured V˙o2peak values at quartiles of CRF, indicating prediction equations have limited ability to predict V˙o2peak at any level of CRF.

Conclusion:

Estimated V˙o2peak using 6MWT distance demonstrated poor agreement with measured V˙o2peak from a CPX. While distance ambulated on the 6MWT remains an important measure of physical performance in patients with HF, prediction equations using 6MWT distance are not appropriate to monitor changes in V˙o2peak following CR in patients with HF.

Internet of Things (IoT) System and Field Sensors for Exercise Intensity Measurements

Although exercise training according to individual peak aerobic capacity ( V ˙ o_2peak ) has been recommended at all ages, sensors available in the field are limited. The most popular sensors in the field are pedometers, but they cannot be used to monitor exercise intensity. Instead, although heart rate (HR) monitors are broadly available in the field to estimate exercise intensity, HR responses to exercise vary by individual according to physical fitness and environmental conditions, which hinders the precise measurement of energy expenditure. These issues make it difficult for exercise physiologists to collaborate with geneticists, nutritionists, and clinicians using the internet of things (IoT). To conquer these problems, we have developed a device that is equipped with a triaxial accelerometer and a barometer to measure energy expenditure during interval walking training (IWT) in the field with inclines. IWT is a training regimen to repeat fast and slow walking for 3 min each, equivalent to greater than 70% and approximately 40% of individual V ˙ o_2peak , respectively. Additionally, we developed an IoT system that enables users to receive instructions from trainers according to their walking records even if they live far away. Since the system is available at low cost with minimum personnel, we can investigate any factors affecting the adherence to and effects of IWT in a large population for a long period. This system was also used to verify any effects of nutritional supplements during IWT and to examine the value of applying IWT to clinical medicine. © 2020 American Physiological Society. Compr Physiol 10:1207-1240, 2020.

The effects of type 2 diabetes mellitus and its complications on physical and pulmonary functions: A case-control study

AIMS

This study was planned to determine the effects of type 2 diabetes mellitus (DM) and its complications on physical and pulmonary functions. Methods: A total of 110 individuals aged 40-65 years were included in the study, 58 with type 2 DM (study group) and 52 without DM (control group). Physical activity level, functional capacity, pulmonary function, and comorbidity levels were compared between the groups. Results: The mean age of the individuals was 52.42 ± 5.88 years. Six-minute walk test distance was 507.2 ± 51.70 m in the study group and 532.23 ± 50.32 m in the control group (p < 0.05, Cohen's d = 0.49). The pulmonary function test results of the study and control groups were determined as forced vital capacity (FVC) (%): 99.17 ± 14.13 and 104.65 ± 16.01 (p > 0.05), forced expiratory volume in one second (FEV1) (%): 96.78 ± 14.43 and 99.73 ± 15.80 (p > 0.05), and FEV1/FVC ratio: 81.97 ± 4.62 and 80.16 ± 5.27 (p > 0.05), respectively. The Charlson Comorbidity Index scores of the study and control groups were 1.83 ± 0.82 and 0.12 ± 0.32 (p < 0.05). Conclusions: Type 2 DM was associated with lower functional capacity and higher rates of comorbid diseases. Therefore, potential causes of these parameters should be considered in the rehabilitation of type 2 diabetic patients.

Muscle mass and physical recovery in ICU: innovations for targeting of nutrition and exercise

PURPOSE OF REVIEW

We have significantly improved hospital mortality from sepsis and critical illness in last 10 years; however, over this same period we have tripled the number of 'ICU survivors' going to rehabilitation. Furthermore, as up to half the deaths in the first year following ICU admission occur post-ICU discharge, it is unclear how many of these patients ever returned home or a meaningful quality of life. For those who do survive, recent data reveals many 'ICU survivors' will suffer significant functional impairment or post-ICU syndrome (PICS). Thus, new innovative metabolic and exercise interventions to address PICS are urgently needed. These should focus on optimal nutrition and lean body mass (LBM) assessment, targeted nutrition delivery, anabolic/anticatabolic strategies, and utilization of personalized exercise intervention techniques, such as utilized by elite athletes to optimize preparation and recovery from critical care.

RECENT FINDINGS

New data for novel LBM analysis technique such as computerized tomography scan and ultrasound analysis of LBM are available showing objective measures of LBM now becoming more practical for predicting metabolic reserve and effectiveness of nutrition/exercise interventions. 13C-Breath testing is a novel technique under study to predict infection earlier and predict over-feeding and under-feeding to target nutrition delivery. New technologies utilized routinely by athletes such as muscle glycogen ultrasound also show promise. Finally, the role of personalized cardiopulmonary exercise testing to target preoperative exercise optimization and post-ICU recovery are becoming reality.

SUMMARY

New innovative techniques are demonstrating promise to target recovery from PICS utilizing a combination of objective LBM and metabolic assessment, targeted nutrition interventions, personalized exercise interventions for prehabilitation and post-ICU recovery. These interventions should provide hope that we will soon begin to create more 'survivors' and fewer victim's post-ICU care.