The relationship between heart rate and VO₂ in moderate-to-severe asthmatics

Abstract

Objective: The main purpose of this study was to evaluate whether the %HRR–%VO₂R relationship and %HRR–VO_2peak relationship are affected in patients with moderate or severe asthma and whether airway obstruction and aerobic capacity influence these relationships.

Methods: A linear regression was calculated using the paired %VO₂R–%HRR and %VO_2peak–%HRR for 93 subjects with asthma. The mean slope and y-intercept were calculated and compared with the line of identity (y-intercept = 0, slope = 1) for all patients and subgroups for the following conditions: low and normal VO_2peak and low and normal FEV₁.

Results: The slope and intercepts of %VO₂R–%HRR were similar to the line of identity for all groups (p > 0.05), and the regressions between %HRR and %VO_2peak did not coincide with the line of identity for all groups (p < 0.05). There were no associations between the intercepts of the %HRR–VO_2peak and the %HRR–%VO₂R relationship with the VO_2peak (p > 0.05) or FEV₁ (p > 0.05).

Conclusions: This is the first study to confirm a constant equivalence between %HRR and %VO₂R in outpatients with moderate or severe asthma. Our data also suggest that the relationship between %HRR and %VO_2peak is unreliable. These results support the use of %HRR in relation to %VO₂R to estimate exercise intensity in this population, independently of the pulmonary function and fitness level.

Keywords:

• Exercise prescription
• physical conditioning
• exercise tolerance
• cardiopulmonary exercise test

Acknowledgements

The authors would like to acknowledge Dr. Júlia M. D. Greve and the exercise physiologist Paulo R Santos-Silva for their support and blinded analysis of the cardiopulmonary exercise testing (Movement Studies Laboratory, Orthopedics and Traumatology Institute, School of Medicine, University of Sao Paulo, Sao Paulo, Brazil) and Professor Clarice Tanaka or technical support (Department of Physical Therapy, School of Medicine, University of Sao Paulo, Sao Paulo, Brazil).

Disclosure statement

The authors of the present study do not have any conflicts of interest to disclose, and there are no relationships with companies/organizations whose products or services may be discussed in this article. The results of the study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation. All authors approved the manuscript and this submission.

Additional information

Funding

This study was supported by São Paulo Research Foundation (FAPESP; Grants 07/56937-0 and 09/53904-9) and Brazilian Nacional Research Council (CNPq; Grants 480869/04-9 and 3114443/2014-1).