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Luniewski J1, Szczegielniak J1, Latawiec K2, Stanisławski R2, Bogacz K1, Krajczy M1, Rydel M2
1Opole University of Technology, Physical Education and Physiotherapy, Opole, Poland, 2Opole University of Technology, Electrical Engineering Automatic Control and Informatics, Opole, Poland
Background: It is essential to determine the optimal level of training loads in patients with pulmonary diseases. For this purpose submaximal exercise test (ET) is usually performed. It defines the amount of effort that a patient can safely perform, and allows to define exercise heart rate limit for each patient. Exercise test result is expressed in Watts or METs. The most commonly used ET protocol for patients with cardiorespiratory dysfunction is modified Bruce treadmill protocol, where the result is expressed in METs. 6MWT is a simple and inexpensive tool for the assessment of functional tolerance of effort and aims at global and integrated assessment of functioning of all systems engaged in fast walking. It shows moderate and high correlation (0.69 r>0.91) with maximal oxygen uptake derived from ET. It is interesting, whether it is possible to effectively estimate the ET results on the basis of 6MWT for wide-spectrum patients with COPD.
Purpose: The aim of this work is to compare the results of the submaximal exercise test and the results of 6MWT (expressed in METs) in patients with COPD and determine mathematical correlations between them.
Methods: The study included 299 patients (140 female, 159 male) with diagnosed COPD (stages I to III) All patients were subjected to a submaximal exercise test and a 6MWT. To develop an optimal mathematical solution and compare the results of the ET and the 6MWT, the least squares and genetic algorithms were employed to estimate parameters of piecewise linear and polynomial expansion models, and Leave-One-Out cross-validation was done.
Results: We justified the nonlinear relationship between VO2max and power output during a submaximal exercise test. This has led to the proposal of nonlinear models relating the energy expenditure in METs with the patient's average velocity during the 6MWT. The above constitutes an original modelling methodology for estimation of submaximal effort tolerance.
Conclusion(s): Many VO2max or MET-involving models are single input, with the input variable being either walk time or velocity or distance, the time has come to thoroughly introduce the second input variable into the treadmill exercise test model, that is the grade. Such a more complex and general model will be a subject of our future research.
Implications: The proposed models and new mathematical formulas can effectively help in the assessment of effort tolerance in clinical practice and potentially in telerehabilitation.
Keywords: COPD, exercise test, 6MWT
Funding acknowledgements: None
Purpose: The aim of this work is to compare the results of the submaximal exercise test and the results of 6MWT (expressed in METs) in patients with COPD and determine mathematical correlations between them.
Methods: The study included 299 patients (140 female, 159 male) with diagnosed COPD (stages I to III) All patients were subjected to a submaximal exercise test and a 6MWT. To develop an optimal mathematical solution and compare the results of the ET and the 6MWT, the least squares and genetic algorithms were employed to estimate parameters of piecewise linear and polynomial expansion models, and Leave-One-Out cross-validation was done.
Results: We justified the nonlinear relationship between VO2max and power output during a submaximal exercise test. This has led to the proposal of nonlinear models relating the energy expenditure in METs with the patient's average velocity during the 6MWT. The above constitutes an original modelling methodology for estimation of submaximal effort tolerance.
Conclusion(s): Many VO2max or MET-involving models are single input, with the input variable being either walk time or velocity or distance, the time has come to thoroughly introduce the second input variable into the treadmill exercise test model, that is the grade. Such a more complex and general model will be a subject of our future research.
Implications: The proposed models and new mathematical formulas can effectively help in the assessment of effort tolerance in clinical practice and potentially in telerehabilitation.
Keywords: COPD, exercise test, 6MWT
Funding acknowledgements: None
Topic: Cardiorespiratory
Ethics approval required: Yes
Institution: Opole Chamber of Physicians
Ethics committee: Committee of Ethics
Ethics number: 139/2012
All authors, affiliations and abstracts have been published as submitted.
