Chest
Volume 135, Issue 2, February 2009, Pages 384-390
Journal home page for Chest

Original Research
COPD
Perceptual and Physiologic Responses During Treadmill and Cycle Exercise in Patients With COPD

https://doi.org/10.1378/chest.08-1258Get rights and content

Background

Although the cycle ergometer is the traditional mode for exercise testing in patients with respiratory disease, this preference over the treadmill does not consider perceptual responses. Our hypotheses were as follows: (1) the regression slope between breathlessness and oxygen consumption (

o2) is greater on the treadmill than on the cycle ergometer; and (2) the regression slope between leg discomfort and
o2 is greater on the cycle ergometer than on the treadmill.

Methods

Twenty patients (10 men/10 women) with COPD (mean ± SD postbronchodilator FEV1, 50 ± 15% of predicted) used a continuous method to report changes in breathlessness and in leg discomfort during cycle and treadmill exercise.

Results

Patients reported an earlier onset of breathlessness and leg discomfort during cycling. Peak ratings of breathlessness were higher on the treadmill, whereas peak ratings of leg discomfort were higher on the cycle ergometer. The regression slopes for breathlessness as a function of

o2 and of minute ventilation (Ve) were higher on the treadmill. The regression slopes between leg discomfort and
o2 were similar for treadmill and cycle exercise. Peak
o2 was significantly higher with treadmill exercise (mean Δ = 8%; p = 0.002).

Conclusions

Patients with COPD exhibit different perceptual and physiologic responses during treadmill walking and cycling. Although ratings of breathlessness are initially higher with cycling at equivalent levels of

o2, the changes in breathlessness as a function of physiologic stimuli (
o2 and Ve) are greater during treadmill exercise. Leg discomfort is the predominant symptom throughout cycling.

Section snippets

Subjects

Inclusion criteria were as follows: age ≥ 50 years; diagnosis of COPD12; ≥ 10 pack-year history of cigarette smoking; ability to exercise on the cycle ergometer and treadmill; and clinically stable COPD. Institutional review board approved the study, and written informed consent was obtained from each participant.

Experimental Protocol

Each patient was tested at three visits, separated from each other by 2 to 4 days. At visit 1, the following assessments were made: medical history, vital signs, current medications,

Results

Descriptive characteristics of the 20 patients are given in Table 1. There were no significant differences for postbronchodilator values for lung function at the two visits. Respiratory medications included the following: albuterol metered-dose inhaler (n = 20); inhaled long-acting β-agonist (n = 13); inhaled short- or long-acting anticholinergic medications (n = 15); inhaled corticosteroids (n = 10); and oral theophylline (n = 4).

Physiologic and perceptual results from incremental

Discussion

Our study demonstrates that patients with COPD exhibit different perceptual and physiologic responses during treadmill walking and cycling. The unique findings are as follows: (1) regression slopes between breathlessness as a function of

o2 and of Ve are significantly higher on the treadmill than on the cycle ergometer; (2) the onset of breathlessness and leg discomfort occurs at a lower
o2 with cycling compared with treadmill walking; and (3) leg discomfort is the predominant symptom

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    Dr. Baird is Scientific Director of Psychological Applications, LLC, which owns the copyright of the continuous measurement program. The other authors have no conflicts of interest to disclose.

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