Comparison of corridor and treadmill walking in patients with severe chronic obstructive pulmonary disease.

pulmonary disease. Dyspnea is a major cause of functional impairment and disability in patients suffering from chronic obstructive pulmonary disease (COPD). Dyspnea limits patients' activity, leading to a cycle of increasing inactivity that in turn aggravates the debilitating effects of the disease.(1) To assess exercise capacity in this patient population, different forms of exercise testing can be used. Exercise testing is necessary in patients with COPD because exercise tolerance cannot be predicted from generally used static pulmonary function tests.(2,3) in an attempt to simplify exercise testing in patients with COPD, maximal walking distance during defined times has been measured. McGavin et al(2) showed a significant correlation between the distance covered in a 12-minute walking test and maximal oxygen consumption measured during a treadmill walking (TMW) exercise in patients with COPD. These authors assessed exercise capacity by measuring the distance covered by the patients along a level hospital corridor during 12 minutes of walking. The advantages of walking during a defined time is the simplicity of performance and the minimum of required measuring devices. Furthermore, test results are reproducible after the initial practice attempts. Patients can perform the test independently and monitor changes in their exercise capacity.(1) The major disadvantage of corridor walking (CW) tests is the lack of information about physiological and symptomatic changes during exercise.(4) Beaumont et al(4) concluded that a self-paced TMW test may be better than either a CW test or a standard progressive exercise test for assessing patients with severe breathlessness. They reported no significant difference in the distance covered during CW and TMW tests. One of the advantages of TMW tests mentioned by these authors was the possibility of heart rate measurement. Currently, simple telemetric devices are available for ambulatory continuous heart rate measurement. This important physiological variable can therefore be monitored easily during CW tests.(5) Our study was undertaken to compare a 12-minute CW procedure with a TMW procedure using continuous ambulatory heart rate measurement in order to evaluate which of the two test procedures is preferable for assessment of exercise tolerance in patients with breathlessness secondary to COPD. Method Subjects Eleven patients (8 men, 3 women) selected from the inpatient population of a rehabilitation center for patients with COPD participated in the study. The patients' mean age was 58 years (age range, 37-73 years). All patients were suffering from severe chronic airway obstruction. Criteria for selection were the presence of marked airway obstruction, defined as a (*) Trainer Paramedi(R), Haarlem, The Netherlands. (t)Polar Electro, Finland. forced expiratory volume in 1 second (FEV[sub.1]) lower than 50% of the reference value,(6) and the absence of reversibility, defined as an increase of FEV[sub.1], lower than 10% of the reference value after inhalation of 0.500 mg of terbutaline. Patients with a history of cardiovascular, neurological, endocrine, and locomotor diseases and those with an arterial oxygen tension below 55 mm Hg were excluded from the study. All patients were informed of the nature of the study, and consent was obtained from each participant. Procedure Medication was standardized: all patients received theophylline in optimal serum levels (range, 8-15 mg/L) and other bronchodilating medications. All patients performed one practice TMW test and one practice CW test before entering the study. Each patient performed CW and TMW tests in random order on two consecutive days between 10:30 and 11:30 AM. Lung function was assessed before exercise testing between 9:30 and 10 AM. The difference of the FEV[sub.1] values between both test days had to be lower than 10%. Lung function data obtained on both test days are summarized in Table 1. The CW test was performed in a level, enclosed corridor according to the method described by McGavin et al.(2) The 100-m waning circuit had two turning points, and the patients walked on a hard floor. The patients were instructed to walk

as far as possible during a 12-minute period. They were told to keep going if possible, but they could slow down or stop if necessary. An investigator (PMJS) accompanied each patient and recorded the distances covered in 2, 6, and 12 minutes. Marking points are placed every 5 m along the walking circuit. The times needed to walk the first and third hundred meters were recorded. Table 1. Lung Function Data of Patients with Chronic Obstructive Pulmonary Disease (N = 11) Before Treadmill Walking (TMW) and Corridor Walking (CW) Tests[Alpha]

Variable[Beta]             TMW                  CW
IVC (L)                   2.83                2.70
FEV[sub.1] (L)            0.96                0.98
IVC (% pred)             75.20                72.10
FEV[sub.1](% pred)       35.10                35.40

[Alpha] No statistically significant intertest differences (p [is greater than] .05).

[Beta]IVC = inspiratory vital capacity; FEV[sub.1]= forced expiratory volume in 1 second. The patients were not encouraged during the TMW test. The TMW test was performed on a calibrated horizontal treadmill,(*) which could be self-paced by the patients during the test by pushing buttons to start, speed up, slow down, or stop the treadmill. The distances covered by the patient were recorded continuously. The same measures assessed during the CW test were assessed during the TMW test. Under resting conditions before the two tests and immediately after the 12-minute CW test, breathlessness was assessed directly by means of a horizontal 100-mm visual analogue scale VAS).7 The left end of the scale was labeled "not at all breathless," and the right end was labeled extremely breathless." The patient was instructed to mark the line at a point that corresponded to his or her breathlessness. The distance of the mark (in millimeters) from zero provided an estimate of dyspnea. The VAS can be considered an appropriate technique for the clinical rating of dyspnea.(8) During the CW and TMW tests, heart rate was continuously monitored by means of the Sport-tester PE 3000(R) exercise device.' This inexpensive telemetric device consists of two elements: 1) the transmitter, a battery-operated electrocardiographic (ECG) monitor, and 2) the receiver, an electronic watch with an antenna housing, capable of receiving signals from the transmitter. The transmitter was strapped to the patient's anterior chest wall with a rubber belt. The heart rate measurement is based on the slope of the upper part of the descending limb of the RS complex in the precordial leads. The mean heart rate is calculated every 2 beats over the last 16 beats and displayed as a digital readout on the receiver. The receiver can store heart rate readings every 5 seconds for 80 minutes. The subject wears the receiver like a wrist watch, and the receiver-transmitter distance does not exceed 1 m. After careful positioning, the transmitter has been shown to be useful and accurate for heart rate monitoring in the absence of continuous arrhythMias.(5) Only patients with a regular sinus rhythm at rest, therefore, were selected for participation in this study. The absence of arrhythmias during exercise was additionally checked by continuous monitoring of ECG responses during the TMW test. Heart rates at different times were obtained by averaging the 5-second readings over a 1-minute period. Heart rate was measured under basal conditions after 1, 2, 6, and 12 minutes of work performance. Data Analysis The CW and TMW test data were compared by Student's paired t tests. Results The TMW and CW test data are summarized in Table 2. All patients were able to perform both exercise tests well; no patient rested during the 12minute CW test. The patients covered a significantly longer distance during the CW test than during the TMW test after 2 (p [is not greater than] .01), 6 p [is not greater than] .01), and 12 (P [is not greater than].05) minutes. Walking speeds during the first (p [is not greater than] .01) and third (p [is not greater than].05) 100m were significantly faster during the CW test than during the TMW test. Heart rate, measured after 1, 2, 6, and 12 minutes of walking, did not differ significantly between the two exercise procedures. After careful positioning of the transmitter, heart rate could be measured without technical problems. During both walking procedures, heart rates increased significantly (p [is not greater than].0001). A slightly higher breathlessness (VAS) score was recorded before the CW test than before the TMW test (p [is not greater than].05). Despite the greater distance walked during the CW test, however, breathiessness scores did not differ significantly at the end of the walking tests. The breathlessness score increase from the pretest to the post-test measurements was 44 and 45 for the TMW and CW tests, respectively. Discussion and Conclusions The measurement of maximal walking distances during defined times has been introduced as a test to evaluate exercise tolerance in patients suffering from COPD. Timed maximal walking distances are frequently used to monitor responses to exercise training programs. In some studies,9-14 however, exercise capacity was evaluated by walking along a corridor, whereas, in a study by Madsen et al,(15) patients were asked to walk on a treadmill during a determined period of time. Little information is available about the outcome of the two test modalities on exercise performance in patients with COPD. In a study by Beaumont et al,(4) CW and TMW were compared in the same group of patients with COPD. The authors found no significant difference in the distances covered during the two procedures, and they concluded that the patients walked on the treadmill in the same way as in the corridor. Furthermore, the authors concluded that the self-paced TMW test has some advantages over the CW test such as the ability to measure gas exchange during exercise, to record ECG responses, to assess breathlessness on a VAS during exercise, and to monitor arterial oxygen saturation by ear oximetry. Timed CW tests, however, have some distinct advantages over TMW tests such as their simplicity of performance and the minimum of required measuring devices. Heart rate responses can easily be measured using simple telemetric devices. Contrary to the results of Beaumont et al,4 the distances walked by the patients in our study were significantly longer on the CW test than on the TMW test, and walking speed was significantly faster on the CW test than on the TMW test. No significant differences in heart rates were found between the two procedures. Using heart rate response as an indicator of exercise intensity, we can therefore conclude that exercise intensity did not differ between the two tests, despite the significantly longer distance walked during the CW test. Therefore, consistent choice of exercise testing procedures is necessary for adequate evaluation of pretraining and posttraining exercise results. No significant differences in breathlessness VAS) scores were found at the end of the two walking tests, suggesting similar subjective feelings of exercise stress. We believe that patients are more familiar with walking in a corridor than on a treadmill and that this fact can explain the differences between the two procedures in this study. Furthermore, this study demonstrated that the same information about exercise tolerance is gained by simple CW as by TMW patients with COPD. Other advantages of the CW procedure are that this test is easy to implement in the monitoring of exercise training programs and that patients can perform the test independently, enabling them to monitor their own exercise training program. References 1 Belman MJ. Exercise in chronic obstructive pulmonary diseases. Clin Chest Med. 1986;7:585-598. 2 McGavin CR, Gupta SP, McHardy GJR. Twelve-minute walking tests for assessing disability in chronic bronchitis. Br Med J. 1976;1:822-823. 3 Swinburn CP, Wakefield JM, jones PW. Performance, ventilation and oxygen consumption in three different types of exercise tests in patients with chronic obstructive lung disease. Thorax 1985;40:581-582. 4 Beaumont A, Cockcroft A, Guz A. A self-paced treadmill walking test for breathless patients. Thorax. 1985;40:459-464. 5 Swerts PMJ, Kretzers LMJ, Mostert R, et al. The 'Sport-tester': a device for exercise monitoring in COPD patients. Journal of Rehabilitation Sciences. In press. 6 Quanjer PH, et al. Standardized lung function testing. Bull Eur Physiopathol Respir. 1983;19(suppl 5):45-51. 7 Aitkin R. Measurements of feelings using visual analogue scales. Proceedings of the Royal Society of Medicine 1959;62:989-993. 8 Mahler DA. Dyspnea: diagnosis and management. Clin Chest Med. 1987;8:215-230. 9 Alison JA, Samios R, Anderson SD. Evaluation of exercise training in patients with chronic airway obstruction. Phys Ther. 1981;61:1273-1277. 10 Cockcroft AE, Saunders MJ, Berry G. Randomised controlled trial of rehabilitation in chronic respiratory disability. Thorax. 1981;36:200-203. 11 Mungall IPF, Hainsworth R. Assessment of respiratory function in patients with chronic airways disease. Thorax. 1979;34:254-258. 12 Mungall IPF, Hainsworth R. An objective assessment of value of exercise training to patients with chronic obstructive airways disease. QJ Med. 1980;193:77-85. 13 Sinclair DJM, Ingram CG. Controlled trial of supervised exercise training in chronic bronchitis. Br Med J. 1980;280:583-588. 14 McGavin CR, Gupta SP, Lloyd EL, et al. Physical rehabilitation for the chronic bronchitic: results of a controlled trial of exercise at the home. Thorax. 1977;32:307-311. 15 Madsen F, Secher NH, Kay L, et al. Inspiratory resistance versus general physical training in patients with chronic obstructive pulmonary disease. Eur J Respir Dis. 1985;67:167-176.

[TABULAR DATA OMITTED]

P Swerts, MD, is Research Fellow, Institute for Rehabilitation Research, Hoensbroek, and Department of Pulmonary Diseases, State University of Limburg, PO Box 1918, 6201 BX Maastricht, The Netherlands. R Mostert, MD, is Medical Director, Asthma Centre Hornerheide, Horn. E Wouters, MD, PhD, is Associate Professor in Pulmonology, Department of Pulmonary Diseases, State University of Limburg. Address all correspondence to Dr Wouters at Department of Pulmonary Diseases, University Hospital Maastricht, PO Box 1918, 6201 BX Maastricht, The Netherlands. This study was approved by the Medical-Ethical Committee of the State University of Limburg. This article was submitted February 28, 1989, and was accepted February 26, 1990.