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A simple, reliable method of assessing exercise capacity in patients with chronic heart failure


Medicine & Science in Sports & Exercise: January 1999 - Volume 31 - Issue 1 - p 52-56
Clinical Sciences: Clinically Relevant

A simple, reliable method of assessing exercise capacity in patients with chronic heart failure. Med. Sci. Sports Exerc., Vol. 31, No. 1, pp. 52-56, 1999.

Objective: The accurate determination of limitations in physical activity is important in evaluating patients with heart failure and in assessing the efficacy of treatment. However, the conventional measures used to evaluate hemodynamics, functional class, and exercise capacity all have limitations. Our objective was to develop a simple method (The Master-Borg test) for evaluating the physical activity of patients with chronic heart failure using self-evaluation of the sensation of dyspnea at a constant workload.

Methods: Patients with NYHA class I (N = 20), class II (N = 20), and class III (N = 20) chronic heart failure performed a symptom-limited treadmill exercise test to determine peak V˙O2 and anaerobic threshold (AT). Patients subsequently performed Master's two-step test for 90 s and maximal dyspnea was self-rated using the visual analog Borg scale (the Master-Borg test).

Results: The mean workload in the Master-Borg test was 15.2 ± 1.6 mL·min−1·kg−1. A significant correlation was found between the Master-Borg score and peak V˙O2 (r = 0.87) or AT (r = 0.84). The reproducibility of the Master-Borg tests was represented by a correlation coefficient of 0.93.

Conclusion: Although simple and inexpensive, the Master-Borg test accurately represents ordinary activity levels, relates the sensation of dyspnea to peak exercise tolerance, and can be completed by most patients with heart failure. Master-Borg scores correlated with peak V˙O2 and AT, and can differentiate among NYHA classes I, II, and III. The Master-Borg test appears to be clinically useful for evaluating the value of physical activity and exercise capacity of patients with chronic heart failure.

First Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya 663, JAPAN

Submitted for publication December 1996.

Accepted for publication December 1997.

Address reprint requests to: Susumu Asakuma, M.D., First Department of Internal Medicine, Hyogo College of Medicine, 1-1, Mukogawa-cho, Nishinomiya 663, Japan.

Chronic heart failure is characterized by a limitation of physical activity due to the development of fatigue and dyspnea. This limitation is used clinically to evaluate the progression of disease and the efficacy of therapy (15). Although such patients are assumed to maintain a low level of physical activity, the level varies even among individuals with heart failure of apparently similar severity (10). Common procedures for assessment of physical activity limitations in patients with chronic heart failure such as functional status, hemodynamics, and exercise capacity all have limitations. The New York Heart Association (NYHA) functional classification criteria is the most common method of assessing the level of activity in patients with chronic heart failure (6). However, because each class can include a wide range of physical activity levels, changes during the patients clinical course may not be reflected in the NYHA classification (5,16,17). Hemodynamic studies bear little or no relationship to measurements of functional status or of exercise capacity. Cardiopulmonary testing, the combination of a treadmill or bicycle maximal exercise test with concurrent measurement of respiratory gas exchange, has gained acceptance as a more precise method for assessment of functional capacity. Maximal V˙O2, as determined by these expensive and cumbersome systems, is the quantity measured to evaluate the functional status of heart failure patients. However, the results of exercise tolerance tests do not always correlate with the NYHA classification (7). Some heart failure patients may not be able to achieve a true maximal V˙O2 for reasons such as the onset of symptoms, hesitancy to experience the discomforts of maximal exercise, or poor effort. These limitations suggest the importance of assessing physical activity not only by exercise capacity using multigraded maximal exercise tests but also by symptom assessment during a constant low-level activity.

The present study investigated a simple method for assessing the effects of low level physical activity in patients with chronic heart failure during exercise testing. Exertional dyspnea during low-level exercise, a major symptom of chronic heart failure, was quantified. Each patient rated the maximal exertional dyspnea experienced during the performance of a two-step test. The reproducibility and clinical utility of this test was evaluated.

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Subjects. Subjects were selected from outpatients of the cardiology section of Hyogo College of Medicine. All subjects had well-compensated heart failure. Their cardiac status had been stable for at least 3 months. Excluded from study were patients with acute heart failure, severe heart failure (NYHA class IV), pulmonary disease, or right heart failure. The 60 Japanese outpatients included in this study (40 male, 20 female; aged 42-65 yr; mean, 57.8 ± 14.2 yr) had at least two sessions on the treadmill and two Master's two-step exercise tests in our section before the current study. By occupation, 42 subjects were retired from office work, and 15 had management positions. The symptom-limiting activity level of 11 subjects was low housework before inclusion in the study, but the other subjects engaged in moderate levels of activity such as yard work, shopping, or walking. Heart failure was caused by old myocardial infarction (OMI) in 35 subjects, dilated cardiomyopathy (DCM) in 10 subjects, and valvular heart disease (VD) in 15 subjects. Latent heart failure was diagnosed in 20 asymptomatic subjects (calcified as NYHA I) due to a past history of symptomatic heart failure. Twenty patients were classified as NYHA II and 20 as NYHA III. The mean cardiothoracic ratio for all subjects was 52% ± 8%, and the range of left ventricular ejection fraction (EF) by echocardiography was between 26% and 55% (average 40%). The EF in subjects with valvular disease (47-55%) was slightly below the normal range. The EF in subjects with DCM (26-36%) indicated severe LV dysfunction. All subjects were receiving drug therapy for heart failure. Digitalis was being administered to 25 subjects, diuretics to 20 calcium antagonists to 15, and ACE inhibitors to 10. Informed consent was obtained from each subject before testing.

Cardiopulmonary exercise testing. All subjects underwent a symptom-limited treadmill exercise test (Stress System ML-5000 Fukuda Denshi Co., Tokyo, Japan) using an original exercise protocol (Table 1). Heart rate (HR), blood pressure (BP), and 12-lead electrocardiogram were continuously monitored during testing. The composition of expired gas was analyzed (System WSMR-1400, Westron Co., Chiba, Japan) (13) at rest for 1-2 min and again during exercise. Oxygen uptake (V˙O2), CO2 production (V˙CO2), ventilatory volume per minute (V˙E), end-respiratory O2 concentration (FET O2), and end-respiratory CO2 concentration (FET CO2) were determined for each breath. The maximum oxygen uptake (peak V˙O2) and anaerobic threshold (AT) were calculated from these measurements. AT was determined according to the method of Wasserman (18). Independent evaluations were performed by two physicians who were blinded to the clinical data on the subjects.



Master-Borg testing. All subjects performed Master's two-step test. Immediately after testing, maximal dyspnea was self-rated using a score in the range of 0-10 according to the visual analog Borg scale (4) (the Master-Borg test). Each patient was required to walk up and over a device that consisted of three steps; two steps were 9 inches above the floor separated by a top step 18 inches high. After going up, over and down the device, the patient turned and repeated the procedure for 90 s (12). The step rate was as prescribed according to Master (9) and was controlled with a metronome. A 12-lead electrocardiogram and O2 uptake were continuously monitored. The maximal O2 uptake during the two-step test (Master V˙O2) was determined by the analysis of expired gas. The Master-Borg test and the symptom-limited treadmill exercise test, were performed within a 3-d period. The Master-Borg test was performed twice (within 7 ± 2 d) in 40 patients. Master-Borg scores were obtained for each test, and the reproducibility of the Master-Borg test was evaluated.

Statistical analysis. Results are expressed as the mean ± SD of values from subjects. The significance of differences between group was evaluated by ANOVA and, where appropriate, Scheffe's test. The correlation between the indicators of exercise tolerance and the Master-Borg scores was examined by the Pearson correlation coefficient method. The reproducibility of the Master-Borg test was examined by the Pearson correlation coefficient method. Agreement between the first and second scores was assessed by the method of Bland and Altman (2). A value of P < 0.05 was accepted as indicating a significant difference in mean values.

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Cardiopulmonary exercise test. The symptom-limited treadmill exercise test was halted at the onset of the complaint of dyspnea (24 subjects) or leg fatigue (36 subjects) at a mean Borg score of 7.3 ± 1.7. The mean maximal HR was 123 ± 32 per minute, and the mean peak V˙O2, was 19.2 ± 5.2 mL·min−1·kg−1 (N = 60). AT was 15.1 ± 4.3 mL·min−1·kg−1 in 49 subjects and could not be detected in 11 subjects.

The Master-Borg test. Each subjects expressed the extent of dyspnea immediately after testing. The mean step rate was 21 ± 3 steps per 90 s. The mean Master was V˙O2 was 15.2 ± 1.6 mL·min−1·kg−1. The Master-Borg scores ranged from 0 to 7 (mean 3.4 ± 2.2) (Fig. 1). A significant correlation was observed between the Master-Borg score and the peak V˙O2 (Fig. 2A) or AT (Fig. 2B).

Figure 1-Di

Figure 1-Di

Figure 2-C

Figure 2-C

The correlation between the Master-Borg scores obtained from the first test and the second test (performed within 7 d) was 0.93 (P < 0.0001) (Fig. 3A). Moreover, the differences between the first and second Master-Borg scores ranged in the mean ± 2 SD except for 1 subject (Fig. 3B).

Figure 3

Figure 3

Relationship between NYHA classification and peak V˙O 2, AT, and Master-Borg scores. The difference in peak V˙O2 and AT between NYHA classes I and III was statistically significant (Table 2). However, no significant differences were observed between classes I and II or between classes II and III. The detection rate of AT was 95% in class I patients, 80% in class II patients, and 70% in class III patients. Although the ability to detect AT decreased with decreasing physical capacity, the Master-Borg score was able to differentiate among the NYHA classes.



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The present results indicate that the Master-Borg test can assess quantitatively the severity of dyspnea that is elicited by low level, single-load exercise. Oka et al. (14) described the level of physical activity and the limitations of physical activity in patients with class I-III congestive heart failure. Peak daily activity involved walking on a flat surface (44%) or general activities such a housework or yard work (42%). Other activities reported as strenuous were recreational activity such as bowling, lifting boxes, and walking uphill. These ordinary physical activities correspond to 3-5 metabolic units and are similar to the exercise level of the Master-Borg test. The workload in the Master-Borg test represents the ordinary activity level of the individual more accurately than does maximal exercise testing. The strong correlation observed between the Master-Borg score and peak exercise tolerance appears to provide a unique insight into the relationship between the sensation of dyspnea and peak exercise tolerance.

The Master's two-step test has decreased in popularity such that a set of Master's steps is difficult to find in the U.S. However, Master's step test is well known worldwide and is inexpensive. Dyspnea is more readily elicited during this step test than during such walking tests as the treadmill exercise test. During bicycle tests, patients feel more leg fatigue than dyspnea and the patient's body weight does not directly influence exercise limits. Also, the workload in the Master's test is more accurately approximates the daily physiological workload. Thus, the Master's two-step test is useful for grading the severity of dyspnea in patients with chronic heart failure.

The original Borg scale was formulated in 1970 for the quantification of symptoms such as shortness of breath and chest pain (3). The Borg 10-point scale used to grade the severity of dyspnea during exercise in the present study was revised to include a smaller number of scores (0-7) (4). The symptoms in each grade are easily explained verbally and the scale is used widely to assess symptoms of dyspnea in a quantitative manner.

No significant differences in peak V˙O2 values were observed between class II subjects and those diagnosed as class I or III. The only significant difference was found between class I and III subjects. However, the Master-Borg score could differentiate among each NYHA class.

The importance of cardiopulmonary exercise test data such as maximal V˙O2, peak V˙O2 and AT for determination of physical activity limitations in patients with chronic heart failure is accepted (7). However, maximal V˙O2 cannot be obtained in many instances because maximal exercise tolerance is limited by symptoms such dyspnea or leg fatigue. AT was first proposed by Wasserman et al. (18) as an important indicator of chronic heart failure and is equivalent to the V˙O2 level that occurs immediately before changes in gas exchange due to metabolic acidosis. Weber et al. (19) proposed a method of classification based on peak V˙O2 and AT. In the present study, the Master-Borg scores strongly correlated with the peak V˙O2 and AT. This correlation indicates that the Master-Borg test may be used to assess exercise capacity in patients with chronic heart failure who may be hesitant to exercise strenuously enough to attain true peak V˙O2.

The Master-Borg score appears to be less objective than the peak V˙O2 and AT. However, the peak V˙O2 is obtained by symptom-limited exercise testing that may produce different results depending on the eagerness of the patient or the examiner and on different end-point symptoms. Peripheral vascular disease and muscular weakness are common in subjects with chronic heart failure. In the present study, patients stopped treadmill tests complaining of leg fatigue rather than of dyspnea. The duration of the Master-Borg test is only 90 s, and no tests were stopped because of leg fatigue.

AT is considered an objective indicator of chronic heart failure, but the rate of detection decreases with increasing severity of heart failure. AT could not be detected in 18% of the subjects in the present study (30% of the subjects with NYHA class III heart failure). In contrast, physical activity assessment was possible by the Master Borg test in all study subjects. Moreover, the Master-Borg test can be performed without an analyzer for expired gases.

Tests in walking for 6 and 12 min have been used to assess the exercise capacity of patients with heart failure (8,11) and may simulate daily activity. However, these tests require a rather large corridor. Although simple and inexpensive, the Master-Borg test reflects level of ordinary activity, relates the sensation of dyspnea to peak exercise tolerance, and can be completed by most patients with heart failure. Master Borg scores correlated with peak V˙O2 and AT and can differentiate among NYHA classes I, II, and III. This test may also be useful in assessing the efficacy of treatment or rehabilitation.

Limitations of study. Chronic heart failure is manifested by dyspnea as well as fatigue of the legs, general fatigue, palpitations, and chest pain. The present study only evaluated dyspnea during single-load exercise. Other symptoms should be included in this exercise protocol. Perception of the sensation of dyspnea may be influenced by the desensitization of the subject to symptoms or by experience with the Master's two-step test. Further study is needed to verify that changes in Master-Borg scores represent changes in exercise capacity and not desensitization to the perception of dyspnea.

We conclude that the Master-Borg test is simple and useful for the clinical assessment of the capacity for physical activity of patients with chronic heart failure.

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