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Effects of exercise training on aerobic capacity and quality of life in individuals with heart failure
Effects of exercise training on aerobic capacity and quality of life in individuals with heart failure Eileen Collins, RN, PhD,a,d W. Edwin Langbein, PhD,a,e Jeanette Dilan-Koetje, RN,a Christine Bammert, MS,a Karla Hanson, MS,a Domenic Reda, PhD,b and Lonnie Edwards, MD,c,e Hines, Chicago, and Maywood, Illinois
PURPOSE: The purpose of this study was to determine whether subjects with chronic heart failure, who completed a 12-week rehabilitation program, would have significantly greater quality of life, better aerobic fitness, less difficulty with symptoms of heart failure, greater self-efficacy for exercise, and higher daily activity levels when compared with subjects in a control group. METHODS: Thirty-one males, aged 64 ⫾ 10 years with left ventricular ejection fraction of 29 ⫾ 7%, were randomized to a moderate intensity supervised aerobic exercise program (n ⫽ 15) or a control group (n ⫽ 16). Twenty-seven subjects completed at least 1 follow-up assessment. RESULTS: After 12 weeks there were significant differences in the change scores for perceived physical function (using RAND Corporation’s 36-item short form) (P ⫽ .025) and peak oxygen uptake (P ⫽ .019) between the exercise and control groups with the exercise group experiencing improved physical function and fitness. CONCLUSIONS: Exercise training in adults with heart failure increases exercise tolerance and perceived physical function. Improved heart failure symptoms, self-efficacy for exercise, or increased physical activity may not be associated with enhancement of exercise tolerance. (Heart Lung® 2004;33: 154-61.)
INTRODUCTION During the past decade, researchers have demonstrated that patients with heart failure (HF) can improve exercise and functional capacity through physical training.1–17 However, results have been equivocal as to the effect of exercise training on overall quality of life (QOL) in patients with HF.12–17 In addition, it is not known whether From the aResearch and Development Service, bCooperative Studies Program, and cDepartment of Medicine, Department of Veterans Affairs, Edward Hines Jr., VA Hospital, Hines, Illinois, the dCollege of Nursing, University of Illinois at Chicago, Chicago, Illinois, and the eDepartment of Medicine, Loyola University Medical Center, Maywood, Illinois. This research was supported by the Department of Veterans Affairs, Veterans Health Administration, Health Services Research and Development Service, Project No. NRI 95-213, and a Career Development grant from Rehabilitation Research and Development, Proposal No. D2191-V. Reprint requests: Eileen Collins, RN, PhD, Research & Development (151), Edward Hines Jr., VA Hospital, Hines, IL 60141. 0147-9563/$ – see front matter Copyright © 2004 by Elsevier Inc. doi:10.1016/j.hrtlng.2003.12.009
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improving physical capacity during treadmill exercise tests translates into reduced symptoms and increased physical activity in daily life. The objectives of this investigation were to determine whether subjects with chronic HF, who completed a 12-week program of cardiopulmonary training, would have significantly greater QOL, better aerobic fitness, less difficulty with symptoms secondary to HF, greater self-efficacy for exercise, and higher daily activity levels when compared with subjects who met bi-weekly with an investigator but did not undergo cardiopulmonary training. An additional objective was to determine whether subjects randomized to the exercise program would continue to show improvement at 24 and 36 weeks and with less frequently scheduled supervised exercise training sessions. This study was approved by the Hospital Human Studies Subcommittee, and all procedures were performed in accordance with institutional guidelines.
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METHODS Research design In this randomized controlled clinical trial, subjects were screened for eligibility, and written consent was obtained. After eligibility for participation in the study was established, each subject completed a health-related QOL questionnaire and underwent a symptom-limited Naughton treadmill test (TMT). The TMT was repeated to establish a stable baseline, and the subject began completing the baseline 3-day physical activity diary. After baseline testing, the subject was randomized to an exercise group or an attention-only control group.
twice and then once weekly during weeks 13 to 24 and once every other week for the final 12 weeks. The control group was seen bi-weekly by the study nurse for attention control. Control subjects were instructed not to change their level of exercise while they were participating in the study. Control group participation ended at 12 weeks. Six months of directed training was chosen because middle-aged and sedentary older adults may need several weeks to adapt to the initial rigors of exercise training and thus require a longer adaptation period to get full benefit from the program. Longer training programs may assist the individual in developing long-term habits thus extending potential benefits.19
Subject selection and screening Subjects were recruited from Midwestern Veteran’s Administration Hospital Cardiology and General Medicine Services and an affiliated University Medical Center Heart Failure Program. Inclusion criteria were: age ⱖ18 years, resting left ventricular ejection fraction ⱕ40% (determined by multi-gated ventricular acquisition scan), New York Heart Association HF Class I to III, stable medication regimen, and study physician’s approval. Exclusion criteria were: unstable HF, unstable dysrhythmia, unstable angina, uncontrolled diabetes, uncontrolled hypertension, anemia, exercise-limiting concurrent condition, cardiac transplant, and current participation in a supervised regular exercise program.
Aerobic fitness training protocol The primary modes of exercise for this study were Polestriding and treadmill walking. PoleStriding is a technique of walking with specially designed poles that require the use of large muscles of the upper body to apply force to the poles. The body mechanics used in PoleStriding are similar to those used in cross-country skiing.18 Subjects polestrided and walked outside when the weather permitted and on a Trackmaster treadmill (JAS Manufacturing, Carrollton, Tex) with a larger belt size [6 ft by 3 ft (1.83 m by 0.91 m)] during inclement weather. Exercise sessions were 3 times per week and included a 5- to 10-minute warm up followed by PoleStriding and/or treadmill walking, and 5-minute active cooldown. Exercise intensity was moderate [50-70% of peak oxygen (O2) uptake] and primarily structured as interval training with an average exercise-to-rest interval ratio of 3:1. Duration of exercise was gradually increased up to 45 to 50 minutes by 12 weeks. An exercise physiologist or nurse supervised training sessions. Supervision was tapered to
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Testing Subjects underwent symptom-limited TMTs, using the Naughton protocol with respiratory gas exchange analysis (2900 Metabolic Measurement Cart; Sensormedics Corporation, Yorba Linda, Calif). The first TMT was primarily used as part of the subject screening process and was repeated to establish a stable baseline. Criteria delineated by the American College of Sports Medicine were used for stopping the exercise test.20 Investigators performing follow-up testing on subjects were blinded to previous test results. Functional aerobic impairment (FAI)21 was computed for each individual as follows: FAI ⫽ (Predicted VO2max – Measured VO2max) ⫼ Predicted VO2max ⫻ 100 [1] where predicted VO2max is derived from a regression equation specific to the gender and level of chronic physical activity engaged in by the individual. FAI is a useful clinical indicator of an individual’s energy reserve. Functional aerobic impairment categories follow: 0-26% ⫽ no significant FAI, 27-40% ⫽ mild impairment, 41-54% ⫽ moderate impairment, 55-68% ⫽ marked impairment, and ⬎68% ⫽ extreme impairment.
QOL questionnaires The Medical Outcomes Study/RAND Corporation’s 36-item short form (SF-36) was used to measure health-related QOL.22 The SF-36 is comprised of 8 scales, all of which have demonstrated high levels of validity, reliability, and stability of scores when administered to patients with HF.22,23 The Minnesota Living with Heart Failure Questionnaire (LHFQ) measured the patient’s perception of the effects of HF on his or her life. Respondents were asked to rank how each factor had prevented
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them from living in the manner that they desire.24 A final score was obtained by summing the responses to the 21 items on the LHFQ. Validity and reliability of the LHFQ have been reported elsewhere.25 The 16-item Cardiac Exercise Self-Efficacy Instrument assessed confidence in performing designated exercise behaviors.26 Validity and reliability of the Cardiac Exercise Self-Efficacy Instrument has been demonstrated by others.26 A 3-day activity diary was used as an ongoing record of participation in physical activities. In 15minute intervals, the time of the physical activity onset and cessation was recorded immediately or shortly after participation. A summary index from the diary was a kilocalorie score derived by adding the products of time spent in a given activity by a previously measured rate of energy expenditure for that activity. When diary kilocalorie expenditure scores have been compared with calorimetry, they have been shown to be accurate indices of daily energy expenditure.27–29 Careful instructions were given to subjects to avoid the overestmation or underestimation of activity. The presence and severity of comorbidities were measured by interview and chart review using the Charlson Comorbidity Index.30 This index was used to determine if comorbid conditions had any influence on the outcomes of the study.
Statistical analysis The change from baseline to 12 weeks in peak oxygen consumption and in the physical function subscale of the SF-36 were chosen a priori as the primary outcome measures for the study. The target sample size of 50 was selected to provide 80% power to detect a mean difference between the 2 randomized groups of 1.3 ⫾ 1.4 mL · kg–1 · min–1 in the change in peak oxygen consumption and 13.0 ⫾ 14.6 in the change in the physical function score. The achieved sample size of 27 provided 80% power to detect a mean difference of 1.7 ⫾ 1.4 mL · kg–1 · min–1 in the change in peak oxygen consumption and 15.0 ⫾ 12.0 in the change in the physical function score. All analyses followed intention-to-treat principles. However, 4 patients had no follow-up data and could not be included in the analysis. Two patients did not complete 12 weeks, so their last available measurements were used. The other 7 subscales of the SF-36 —symptoms from HF, selfefficacy for exercise, and home activity—were considered secondary outcome measures. Measures of central tendency were used to describe the variables and demographic characteris-
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tics. The Mann–Whitney U tests for independent groups were used to analyze the between-group differences in change scores on the primary outcome variables [QOL and oxygen consumption (mL · kg-1 · min–1)]. All statistical tests were 2-sided. ␣ ⫽ 0.025 was the criterion for statistical significance for each primary outcome measure. ␣ ⫽ 0.05 was used for all other statistical tests. Wilcoxon non-parametric statistics were used to assess changes within groups. Statistical analysis was completed using SPSS 11.5 for Windows statistical package (Chicago, Ill).
RESULTS Subjects Fifty-one subjects met the inclusion criteria and gave their written informed consent. Of these 51 volunteers, 31 males completed baseline testing and were randomized into one of 2 experimental groups (n ⫽ 15 exercise, n ⫽ 16 control). Of the 20 subjects not randomized, 12 had a left ventricular ejection fraction greater than 40%, 3 had positive stress tests precluding participation, 3 failed to keep scheduled appointments, 1 had unstable HF, and 1 had uncontrolled blood pressure. A summary of study participants’ demographic information is presented in Table I. The Charlson Comorbidity Index score was calculated for the exercise and control groups. No significant differences were observed between the 2 groups (exercise ⫽ 3.5 ⫾ 1.5, control ⫽ 4.0 ⫾ 1.6, P ⫽ .42) in comorbid conditions or other major study variables at baseline (P ⬎ .05). Twenty-five subjects completed the 12-week program, 1 completed 10 weeks, and 1 completed at least 6 weeks. Thus, follow-up data were available for 27 subjects (n ⫽ 12 exercise group, n ⫽ 15 control group). Two exercise subjects were withdrawn from the study for medical reasons (worsening HF and gout). Two subjects withdrew for other reasons [non-compliance, missed numerous appointments without explanation (n ⫽ 2; 1 exercise group, 1 control group)]. Table I displays demographic characteristics by treatment group for the patients included in the analysis.
Naughton TMT Subjects completed the TMT protocol at least twice. If the oxygen uptake was within 5% of the previous test, the subject continued with other baseline testing. If the variation was greater than 5%, the subject completed a third test. Four of the 31 randomized subjects required a third test, and 1
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Table I Demographic information at baseline for subjects randomized to the exercise (n ⫽ 12) and control (n ⫽ 15) groups GROUP Parameter
Exercise
Control
P value
Age (y) Education LVEF (%) Body weight (kg) Body mass index VO2peak (mL · kg–1 · min–1) Functional aerobic impairment No impairment (n) Mild Impairment (n) Moderate Impairment (n) Marked Impairment (n) Extreme Impairment (n)
62.7 ⫾ 11.2 12.5 ⫾ 1.5 31.7 ⫾ 6.9 90.0 ⫾ 18.7 28.9 ⫾ 6.0 17.8 ⫾ 5.7
66.2 ⫾ 9.8 12.7 ⫾ 2.1 29.9 ⫾ 6.2 89.6 ⫾ 12.8 29.2 ⫾ 3.9 16.3 ⫾ 5.0
.37 .98 .38 .61 .43 .58
2 3 6 3 1
2 3 7 4 0
LVEF, Left ventricular ejection fraction; body mass index, [weight (kg) ⫼ height (m2)].
subject required a fourth test. Results used for analysis were taken from the baseline test with the highest peak oxygen uptake value. During the first 6 weeks of exercise training, work intensity averaged 59 ⫾ 13% of the oxygen uptake reserve. During weeks 7 through 12, work intensity increased to 73 ⫾ 19% and 81 ⫾ 21% during weeks 13 through 24. Significant changes were observed in oxygen consumption after 12 weeks between the exercising group and non-exercising group. Oxygen uptake improved by 0.7 and 1.6 mL · kg–1 · min–1 over the 6 and 12 weeks, respectively, in the exercising group, whereas the non-exercising group declined by 0.7 and 0.8 mL · kg–1 · min–1. Differences in oxygen uptake between the 2 groups at 12 weeks was statistically significant (P ⫽ .019). Additional fitness gains were observed in those subjects that continued to exercise at 24 (P ⫽ .001) and 36 weeks (P ⫽ .14). The most common reasons for terminating the exercise test were fatigue and dyspnea. As a result of improved fitness, 4 subjects in the exercise group moved up 1 level in FAI (moderate-to-mild impairment, n ⫽ 2; marked-to-moderate impairment, n ⫽ 2), whereas, 5 subjects in the control group moved down 1 category, and 2 subjects moved up 1 category (no impairment to mild impairment, n ⫽ 1; mild-to-moderate impairment, n ⫽ 1; moderate-tomarked impairment, n ⫽ 3; marked-to-moderate impairment, n ⫽ 2).
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Quality of life When the exercising group was compared with the control group, there was a significant improvement in the perceived physical function subscale change score of the SF-36. The perception of physical functioning in the exercising group increased by 10.4 ⫾ 18.5 points (14%) from baseline to 12 weeks, whereas the control group declined by 4.7 ⫾ 12.4 points during the 12 weeks (P ⫽ .025) (see Table II). No other significant differences were observed between the groups. Subjects who continued to exercise maintained significant improvements in perceived physical function at 24 weeks (P ⫽ .04).
Symptoms from HF At 12 weeks, subjects in the exercising group (24.9 ⫾ 11.9 to 21.7 ⫾ 17.7; 13% decline, P ⫽ .50) and control group (31.9 ⫾ 18.7 to 31.8 ⫾ 20.2, P ⫽ .70) reported no change in difficulty living with their symptoms from HF. Difference in the change score on the LHFQ was not statistically significant between the 2 groups (change exercise group ⫽ –3.2 ⫾ 13.7; change control group ⫽ – 0.1 ⫾ 13.4, P ⫽ .75). Negative scores denote a perception of less difficulty in living with symptoms of HF.
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Table II SF-36 subscale change scores (⌬ ⫽ 12-week score ⫺ baseline score) for subjects in the exercise (n ⫽ 12) and control (n ⫽ 15) groups. Results (P value) of the independent t tests are also presented. Exercise group
Control group
SF-36 subscale
⌬ Score
⌬ Score
P value
Physical function General health Vitality Mental health Role physical Role emotional Social function Body pain
10.4 ⫾ 18.5 ⫺4.2 ⫾ 24.1 ⫺4.2 ⫾ 12.8 2.3 ⫾ 13.0 ⫺6.3 ⫾ 24.0 2.8 ⫾ 36.1 1.7 ⫾ 42.6 ⫺7.2 ⫾ 23.3
⫺4.7 ⫾ 12.5 0.7 ⫾ 22.9 6.7 ⫾ 21.7 1.8 ⫾ 18.8 1.7 ⫾ 24.0 2.2 ⫾ 26.6 ⫺1.3 ⫾ 25.3 3.9 ⫾ 25.4
.025 .87 .24 .68 .46 .46 .94 .14
Self-efficacy for exercise Self-efficacy for exercise was higher in the exercising group when compared with the control group (change exercise group ⫽ 7.7 ⫾ 12.0; change control group ⫽ 0.4 ⫾ 13.6, P ⫽ .10). Although the difference in the change score between the 2 groups was not statistically significant, significant within-group improvements were observed in the exercise but not the control group. Subjects in the exercising group reported improved self-efficacy after 12 weeks of training [(55.3 ⫾ 12.1 to 63.0 ⫾ 10.9, P ⫽ .10); 17% improvement], whereas there was no change in the self-efficacy score (52.5 ⫾ 16.3 to 52.9 ⫾ 14.7, P ⫽ .83) of the control group. Self-efficacy improvements were maintained for those subjects that continued to exercise at 24 (22%, P ⫽ .01) and 36 (40%, P ⫽ .06) weeks.
Activity diaries Overall activity level was not significantly increased (P ⫽ .94) when the change in kilocalories expended from baseline to 12 weeks was compared in the exercise (2231 ⫾ 382 kcal to 2426 ⫾ 751 kcal) and the control group (2269 ⫾ 893 kcal to 2395 ⫾ 648 kcal). Subjects’ compliance with completing the activity diaries was poor (57%), and we do not consider these results to best reflect true physical activity parameters.
Adherence Because 3 of 15 subjects assigned to the exercise group withdrew or were withdrawn from the study before collection of any follow-up data, baseline characteristics of the exercise group were compared
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for differences between those who were included in the analyses versus those who were not. Descriptive data follow in Table III. Those who were included in the analysis were more fit as measured by oxygen uptake (11.3 ⫾ 1.7 vs 17.8 ⫾ 5.7 mL · kg–1 · min–1, P ⫽ .03), had a higher self-efficacy for exercise (36.0 ⫾ 11 vs 55.3 ⫾ 12.1, P ⫽ .03) and had a higher level of education (10.0 ⫾ 2.0 vs 12.5 ⫾ 1.5 yr, P ⫽ .05).
DISCUSSION After 12 weeks, there was a significant difference in the change score between the exercise and control group on the physical function subscale of the SF-36. A moderate-to-large improvement in physical function was observed in the exercise group accompanied by a small decline in the control group. The present study is one of only a few studies that have demonstrated an improvement in QOL in a randomized controlled trial.13,16,17,31 Austrian investigators observed significant improvements in vitality, physical role, physical function, and social function in a group of chronic HF subjects randomized to 3 months of exercise compared with a non-exercising control group (total n ⫽ 25).13 Likewise, another group observed that feelings of disability significantly decreased and overall feelings of general well-being significantly improved after an exercise intervention in 67 subjects with HF randomized to an exercise training or control group.31 Conversely, Gottlieb et al14 observed no significant changes in QOL as measured by the SF-36 in 33 elderly subjects with HF randomized to 6 months of supervised exercise or usual activity. Most investigations of exercise and HF continue to focus on physiologic
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Table III Baseline characteristics of subjects randomized to the exercise group who completed ⬍6 weeks of the study and 6 weeks of the study
Baseline parameter
Completed < 6 wks nⴝ3
Completed > 6 wks n ⴝ 12
P value
Age (y) LVEF (%) Education (y) Comorbidity index score Oxygen uptake (mL · kg–1 · min–1) LHFQ score Self-efficacy for exercise score Physical function subscale
63 ⫾ 8 22.7 ⫾ 7.5 10.0 ⫾ 2.0 4.7 ⫾ 2.1 11.3 ⫾ 1.7 38.7 ⫾ 28.1 36.0 ⫾ 11.0 48.3 ⫾ 20.2
63 ⫾ 11 31.7 ⫾ 5.6 12.5 ⫾ 1.5 3.2 ⫾ 1.3 17.8 ⫾ 5.7 24.9 ⫾ 11.9 55.3 ⫾ 12.1 64.2 ⫾ 26.3
.95 .06 .05 .18 .03 .28 .03 .34
LVEF, Left ventricular ejection fraction; LHFQ, living with heart failure questionnaire (range ⫽ a lower score is a better score).
measures of change. It is important that perceptual measures be incorporated in clinical trials, because patients are less likely to continue with prescribed therapy unless they perceive benefits. After 12 weeks, aerobic fitness, as measured by improvements in peak oxygen consumption, increased by 9% in the exercise group and declined by 5% in the control group. On average, the subjects in the exercise group moved up 1 full classification from moderate impairment to mild impairment after aerobic training. The lower the FAI, the more reserve a person has to perform activities of daily living without excessive strain. It is concluded that the supervised conditioning program used in the present study successfully increased the aerobic fitness of the subjects in the exercise group, and this improvement was significantly greater than changes experienced by individuals in the control group. Subjects that stayed on in the exercise program continued to improve their fitness level through 6 months, increasing their oxygen uptake by an additional 7% beyond the 3-month measurements. Improvements in perceived physical function were also maintained. Although there was a slight decline in fitness at 9 months (3%), the overall oxygen uptake was still markedly greater than observed at baseline (12%). Traditional cardiac rehabilitation programs are on average limited to 3 months duration. After receiving the diagnosis of HF, establishing or reestablishing confidence in one’s ability to exercise clearly requires a rehabilitation program of sufficient duration with skilled professional supervision to overcome fear and other perceived barriers to
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engaging in a regular program of physical activity. For this chronically ill, sedentary population, longer training programs may be needed to effect sustained change. It is notable that self-efficacy for exercise continued to improve at 6 and 9 months, even as supervised exercise was tapered. A 3-day activity diary was used to collect information regarding subjects’ level of physical activity. Subjects’ compliance with completing activity diaries was poor (57%). Available data were analyzed, and no significant differences were found in activity level between the groups at baseline or 12 weeks. In addition, there were no differences in activity patterns from baseline to 12 weeks in the exercise or control groups. These findings were consistent with those of other investigators who used the Caltrac (Muscle Dynamics, Torrance, Calif) and doubly labeled water to measure energy expenditure.14 Perhaps more focused attention is needed in translating improvements in exercise capacity to a more active lifestyle. Rehabilitation programs that focus on more activities common to this age group may be more successful in translating increased fitness to increased physical activity in daily life. Also, a more robust and less burdensome method for data collection is needed. Twenty-seven (87%) of the 31 subjects who completed baseline testing and randomization completed at least 6 weeks of the study and were included in the analysis. There were 3 withdrawals in the exercise group (20%) and 1 in the control group (6%). This withdrawal rate is similar to
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those reported in previous investigations of training elderly HF subjects32 but slightly higher than those reported in comparable studies with younger subjects.14,31 Examination of baseline demographic characteristics revealed no significant differences between the exercise and the control groups on variables often used to predict exercise capacity. Those who withdrew from the exercise group, however, appeared to have a more severe illness profile than those who completed the study (see Table III). Confidence in the ability to exercise (self-efficacy) and oxygen uptake were significantly lower in subjects who withdrew from the exercise portion of the study than in those subjects in the exercise group who completed at least 6 weeks of the study. Although not statistically significant, it is notable that at baseline those who withdrew early from the study had a lower left ventricular ejection fraction. Likewise, they had higher comorbidity scores and reported more difficulty with symptoms from HF than those subjects who completed the protocol. More study is needed to develop a specific profile of patients with HF who can be expected to complete a rehabilitation program and those at risk for recidivism.
CONCLUSION A moderate-to-moderately-high intensity exercise training program is a safe and effective method for improving aerobic fitness in persons with chronic HF. Along with successful physiologic adaptations to exercise training, HF patients’ perceived physical function was significantly greater than subjects randomized to a control group. Those participating in the supervised exercise program perceived improvements in self-efficacy for exercise, whereas control subjects did not. In addition, exercise subjects reported less difficulty with symptoms from HF. Lastly, HF subjects continued to benefit from exercise training far beyond the traditional 12-week cardiac rehabilitation program.
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Collins et al 4. Sullivan MJ, Higginbotham MB, Cobb FR. Exercise training in patients with chronic heart failure delays ventilatory anaerobic threshold and improves submaximal exercise performance. Circulation 1989;79:324-9. 5. Keteyian SJ, Levine AB, Brawner CA, et al. Exercise training in patients with heart failure. A randomized, controlled trial. Ann Intern Med 1996;124:1051-7. 6. Coats AJS, Adamopoulos S, Meyer TE, et al. Effects of physical training in chronic heart failure. Lancet 1990;335:63-6. 7. Jette´ M, Heller R, Landry F, et al. Randomized 4-week exercise program in patients with impaired left ventricular function. Circulation 1991;84:1561-7. 8. Shephard RJ, Kavanagh T, Mertens DJ. On the prediction of physiological and psychological responses to aerobic training in patients with stable congestive heart failure. J Cardiopulm Rehabil 1998;18(1):45-51. 9. Kiilavuori K, Sovijarvi A, Naveri H, et al. Effect of physical training on exercise capacity and gas exchange in patients with chronic heart failure. Chest 1996;110(4):985-91. 10. Kavanagh T, Myers MG, Baigrie RS, et al. Quality of life and cardiorespiratory function in chronic heart failure. effects of 12 months’ aerobic training. Heart 1996;76(1):42-9. 11. Tyni-Lenne R, Gordon A, Jensen-Urstad M, et al. Aerobic training involving minor muscle mass shows greater efficiency than training involving a major muscle mass in chronic heart failure patients. J Card Fail 1999;5(4):300-7. 12. Tokmakova M, Dobreva B, Kostianev S. Effects of short-term exercise training in patients with heart failure. Folia Medica 1999;41:68-71. 13. Gottlieb SS, Fisher ML, Freudenberger R, et al. Effects of exercise training on peak performance and quality of life in congestive heart failure patients. J Card Fail 1999;5(3):188-94. 14. Quittan M, Sturm B, Wiesinger GF, et al. Quality of life in patients with chronic heart failure. a randomized controlled trial of changes induced by a regular exercise program. Scand J Rehabil Med 1999;31:223-8. 15. Balardinelli R, Georgiou D, Cianci G, et al. Randomized, controlled trial of long-term moderate exercise training in chronic heart failure. effects of functional capacity, quality of life, and clinical outcome. Circulation 1999;99:1173-82. 16. Willenheimer R, Erhardt L, Cline C, et al. Exercise training in heart failure improves quality of life and exercise capacity. Eur Heart J 1998;19:774-81. 17. Gordon A, Tyni-Lenne R, Jansson E, et al. Improved ventilation and decreased sympathetic stress in chronic heart failure patients following local endurance training with leg muscles. J Card Fail 1997;3:3-12. 18. Rutlin T. Exerstrider total fitness/total body exercise owner’s manual and instruction guide. Exerstrider Products Inc: Madison (WI), 1992. 19. Daumer R, Miller SM. Effects of cardiac rehabilitation on psychosocial functioning and life satisfaction of coronary artery disease clients. Rehabil Nurs 1992;17:69-74. 20. American College of Sports Medicine. The recommended quantity and quality of exercise for developing and maintaining cardiorespiratory and muscular fitness in healthy adults. Med Sci Sports Exerc 1990;22:265-74. 21. Bruce RA, Kusumi F, Hosmer D. Maximal oxygen intake and normographic assessment of functional aerobic impairment in cardiovascular disease. Am Heart J 1973;85:54662. 22. Sneed NV, Paul S, Michel Y, Van Bakel A, Hendrix G. Evaluation of 3 quality of life measurement tools in patients with chronic heart failure. Heart Lung 2001;30:332-40. 23. Wolinsky FD, Wyrwich KW, Nienaber NA, Tierney WM. Generic versus disease-specific health status measures. Eval Health Prof 1998;21:216-43. 24. Rector TS, Kubo SH, Cohn JN. Patients’ self-assessment of their congestive heart failure. Heart Fail 1987;3:198-209.
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25. Rector TS, Kubo SH, Cohn JN. Validity of the Minnesota Living with Heart Failure Questionnaire as a measure of therapeutic response to enalapril or placebo. Am J Card 1993;71:1106-7. 26. Hickey M, Owen SV, Froman RD. Instrument development. cardiac diet and exercise self-efficacy. Nurs Res 1992;41:34751. 27. Acheson KJ, Campbell IT, Edholm OG, et al. The measure of daily energy expenditure—an evaluation of some techniques. Am J Clin Nutr 1980;33:1155-64. 28. Bouchard C, Trembley A, Leblanc C, et al. A method to assess energy expenditure in children and adults. Am J Clin Nutr 1983;37:461-7. 29. Haskell WL, Leon AS, Caspersen CJ, et al. Cardiovascular benefits and assessment of physical activity and physical fitness in adults. Med Sci Sports Exerc 1992;24:S201-20. 30. Charlson ME, Pompei P, Ales K, et al. A new method of classifying prognostic co morbidity in longitudinal studies. development and validation. J Chronic Dis 1987;40: 373-83. 31. Wielenga RP, Erdman RA, Huisveld IA, et al. Effect of exercise training on quality of life in patients with chronic heart failure. J Psychosom Res 1998;45:459-64. 32. Owen A, Croucher L. Effects of an exercise programme for elderly patients with heart failure. Eur J Heart Fail 2000;2:6570.
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PURPOSE: The purpose of this study was to determine whether subjects with chronic heart failure, who completed a 12-week rehabilitation program, would have significantly greater quality of life, better aerobic fitness, less difficulty with symptoms of heart failure, greater self-efficacy for exercise, and higher daily activity levels when compared with subjects in a control group. METHODS: Thirty-one males, aged 64 ⫾ 10 years with left ventricular ejection fraction of 29 ⫾ 7%, were randomized to a moderate intensity supervised aerobic exercise program (n ⫽ 15) or a control group (n ⫽ 16). Twenty-seven subjects completed at least 1 follow-up assessment. RESULTS: After 12 weeks there were significant differences in the change scores for perceived physical function (using RAND Corporation’s 36-item short form) (P ⫽ .025) and peak oxygen uptake (P ⫽ .019) between the exercise and control groups with the exercise group experiencing improved physical function and fitness. CONCLUSIONS: Exercise training in adults with heart failure increases exercise tolerance and perceived physical function. Improved heart failure symptoms, self-efficacy for exercise, or increased physical activity may not be associated with enhancement of exercise tolerance. (Heart Lung® 2004;33: 154-61.)
INTRODUCTION During the past decade, researchers have demonstrated that patients with heart failure (HF) can improve exercise and functional capacity through physical training.1–17 However, results have been equivocal as to the effect of exercise training on overall quality of life (QOL) in patients with HF.12–17 In addition, it is not known whether From the aResearch and Development Service, bCooperative Studies Program, and cDepartment of Medicine, Department of Veterans Affairs, Edward Hines Jr., VA Hospital, Hines, Illinois, the dCollege of Nursing, University of Illinois at Chicago, Chicago, Illinois, and the eDepartment of Medicine, Loyola University Medical Center, Maywood, Illinois. This research was supported by the Department of Veterans Affairs, Veterans Health Administration, Health Services Research and Development Service, Project No. NRI 95-213, and a Career Development grant from Rehabilitation Research and Development, Proposal No. D2191-V. Reprint requests: Eileen Collins, RN, PhD, Research & Development (151), Edward Hines Jr., VA Hospital, Hines, IL 60141. 0147-9563/$ – see front matter Copyright © 2004 by Elsevier Inc. doi:10.1016/j.hrtlng.2003.12.009
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improving physical capacity during treadmill exercise tests translates into reduced symptoms and increased physical activity in daily life. The objectives of this investigation were to determine whether subjects with chronic HF, who completed a 12-week program of cardiopulmonary training, would have significantly greater QOL, better aerobic fitness, less difficulty with symptoms secondary to HF, greater self-efficacy for exercise, and higher daily activity levels when compared with subjects who met bi-weekly with an investigator but did not undergo cardiopulmonary training. An additional objective was to determine whether subjects randomized to the exercise program would continue to show improvement at 24 and 36 weeks and with less frequently scheduled supervised exercise training sessions. This study was approved by the Hospital Human Studies Subcommittee, and all procedures were performed in accordance with institutional guidelines.
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METHODS Research design In this randomized controlled clinical trial, subjects were screened for eligibility, and written consent was obtained. After eligibility for participation in the study was established, each subject completed a health-related QOL questionnaire and underwent a symptom-limited Naughton treadmill test (TMT). The TMT was repeated to establish a stable baseline, and the subject began completing the baseline 3-day physical activity diary. After baseline testing, the subject was randomized to an exercise group or an attention-only control group.
twice and then once weekly during weeks 13 to 24 and once every other week for the final 12 weeks. The control group was seen bi-weekly by the study nurse for attention control. Control subjects were instructed not to change their level of exercise while they were participating in the study. Control group participation ended at 12 weeks. Six months of directed training was chosen because middle-aged and sedentary older adults may need several weeks to adapt to the initial rigors of exercise training and thus require a longer adaptation period to get full benefit from the program. Longer training programs may assist the individual in developing long-term habits thus extending potential benefits.19
Subject selection and screening Subjects were recruited from Midwestern Veteran’s Administration Hospital Cardiology and General Medicine Services and an affiliated University Medical Center Heart Failure Program. Inclusion criteria were: age ⱖ18 years, resting left ventricular ejection fraction ⱕ40% (determined by multi-gated ventricular acquisition scan), New York Heart Association HF Class I to III, stable medication regimen, and study physician’s approval. Exclusion criteria were: unstable HF, unstable dysrhythmia, unstable angina, uncontrolled diabetes, uncontrolled hypertension, anemia, exercise-limiting concurrent condition, cardiac transplant, and current participation in a supervised regular exercise program.
Aerobic fitness training protocol The primary modes of exercise for this study were Polestriding and treadmill walking. PoleStriding is a technique of walking with specially designed poles that require the use of large muscles of the upper body to apply force to the poles. The body mechanics used in PoleStriding are similar to those used in cross-country skiing.18 Subjects polestrided and walked outside when the weather permitted and on a Trackmaster treadmill (JAS Manufacturing, Carrollton, Tex) with a larger belt size [6 ft by 3 ft (1.83 m by 0.91 m)] during inclement weather. Exercise sessions were 3 times per week and included a 5- to 10-minute warm up followed by PoleStriding and/or treadmill walking, and 5-minute active cooldown. Exercise intensity was moderate [50-70% of peak oxygen (O2) uptake] and primarily structured as interval training with an average exercise-to-rest interval ratio of 3:1. Duration of exercise was gradually increased up to 45 to 50 minutes by 12 weeks. An exercise physiologist or nurse supervised training sessions. Supervision was tapered to
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Testing Subjects underwent symptom-limited TMTs, using the Naughton protocol with respiratory gas exchange analysis (2900 Metabolic Measurement Cart; Sensormedics Corporation, Yorba Linda, Calif). The first TMT was primarily used as part of the subject screening process and was repeated to establish a stable baseline. Criteria delineated by the American College of Sports Medicine were used for stopping the exercise test.20 Investigators performing follow-up testing on subjects were blinded to previous test results. Functional aerobic impairment (FAI)21 was computed for each individual as follows: FAI ⫽ (Predicted VO2max – Measured VO2max) ⫼ Predicted VO2max ⫻ 100 [1] where predicted VO2max is derived from a regression equation specific to the gender and level of chronic physical activity engaged in by the individual. FAI is a useful clinical indicator of an individual’s energy reserve. Functional aerobic impairment categories follow: 0-26% ⫽ no significant FAI, 27-40% ⫽ mild impairment, 41-54% ⫽ moderate impairment, 55-68% ⫽ marked impairment, and ⬎68% ⫽ extreme impairment.
QOL questionnaires The Medical Outcomes Study/RAND Corporation’s 36-item short form (SF-36) was used to measure health-related QOL.22 The SF-36 is comprised of 8 scales, all of which have demonstrated high levels of validity, reliability, and stability of scores when administered to patients with HF.22,23 The Minnesota Living with Heart Failure Questionnaire (LHFQ) measured the patient’s perception of the effects of HF on his or her life. Respondents were asked to rank how each factor had prevented
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them from living in the manner that they desire.24 A final score was obtained by summing the responses to the 21 items on the LHFQ. Validity and reliability of the LHFQ have been reported elsewhere.25 The 16-item Cardiac Exercise Self-Efficacy Instrument assessed confidence in performing designated exercise behaviors.26 Validity and reliability of the Cardiac Exercise Self-Efficacy Instrument has been demonstrated by others.26 A 3-day activity diary was used as an ongoing record of participation in physical activities. In 15minute intervals, the time of the physical activity onset and cessation was recorded immediately or shortly after participation. A summary index from the diary was a kilocalorie score derived by adding the products of time spent in a given activity by a previously measured rate of energy expenditure for that activity. When diary kilocalorie expenditure scores have been compared with calorimetry, they have been shown to be accurate indices of daily energy expenditure.27–29 Careful instructions were given to subjects to avoid the overestmation or underestimation of activity. The presence and severity of comorbidities were measured by interview and chart review using the Charlson Comorbidity Index.30 This index was used to determine if comorbid conditions had any influence on the outcomes of the study.
Statistical analysis The change from baseline to 12 weeks in peak oxygen consumption and in the physical function subscale of the SF-36 were chosen a priori as the primary outcome measures for the study. The target sample size of 50 was selected to provide 80% power to detect a mean difference between the 2 randomized groups of 1.3 ⫾ 1.4 mL · kg–1 · min–1 in the change in peak oxygen consumption and 13.0 ⫾ 14.6 in the change in the physical function score. The achieved sample size of 27 provided 80% power to detect a mean difference of 1.7 ⫾ 1.4 mL · kg–1 · min–1 in the change in peak oxygen consumption and 15.0 ⫾ 12.0 in the change in the physical function score. All analyses followed intention-to-treat principles. However, 4 patients had no follow-up data and could not be included in the analysis. Two patients did not complete 12 weeks, so their last available measurements were used. The other 7 subscales of the SF-36 —symptoms from HF, selfefficacy for exercise, and home activity—were considered secondary outcome measures. Measures of central tendency were used to describe the variables and demographic characteris-
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tics. The Mann–Whitney U tests for independent groups were used to analyze the between-group differences in change scores on the primary outcome variables [QOL and oxygen consumption (mL · kg-1 · min–1)]. All statistical tests were 2-sided. ␣ ⫽ 0.025 was the criterion for statistical significance for each primary outcome measure. ␣ ⫽ 0.05 was used for all other statistical tests. Wilcoxon non-parametric statistics were used to assess changes within groups. Statistical analysis was completed using SPSS 11.5 for Windows statistical package (Chicago, Ill).
RESULTS Subjects Fifty-one subjects met the inclusion criteria and gave their written informed consent. Of these 51 volunteers, 31 males completed baseline testing and were randomized into one of 2 experimental groups (n ⫽ 15 exercise, n ⫽ 16 control). Of the 20 subjects not randomized, 12 had a left ventricular ejection fraction greater than 40%, 3 had positive stress tests precluding participation, 3 failed to keep scheduled appointments, 1 had unstable HF, and 1 had uncontrolled blood pressure. A summary of study participants’ demographic information is presented in Table I. The Charlson Comorbidity Index score was calculated for the exercise and control groups. No significant differences were observed between the 2 groups (exercise ⫽ 3.5 ⫾ 1.5, control ⫽ 4.0 ⫾ 1.6, P ⫽ .42) in comorbid conditions or other major study variables at baseline (P ⬎ .05). Twenty-five subjects completed the 12-week program, 1 completed 10 weeks, and 1 completed at least 6 weeks. Thus, follow-up data were available for 27 subjects (n ⫽ 12 exercise group, n ⫽ 15 control group). Two exercise subjects were withdrawn from the study for medical reasons (worsening HF and gout). Two subjects withdrew for other reasons [non-compliance, missed numerous appointments without explanation (n ⫽ 2; 1 exercise group, 1 control group)]. Table I displays demographic characteristics by treatment group for the patients included in the analysis.
Naughton TMT Subjects completed the TMT protocol at least twice. If the oxygen uptake was within 5% of the previous test, the subject continued with other baseline testing. If the variation was greater than 5%, the subject completed a third test. Four of the 31 randomized subjects required a third test, and 1
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Table I Demographic information at baseline for subjects randomized to the exercise (n ⫽ 12) and control (n ⫽ 15) groups GROUP Parameter
Exercise
Control
P value
Age (y) Education LVEF (%) Body weight (kg) Body mass index VO2peak (mL · kg–1 · min–1) Functional aerobic impairment No impairment (n) Mild Impairment (n) Moderate Impairment (n) Marked Impairment (n) Extreme Impairment (n)
62.7 ⫾ 11.2 12.5 ⫾ 1.5 31.7 ⫾ 6.9 90.0 ⫾ 18.7 28.9 ⫾ 6.0 17.8 ⫾ 5.7
66.2 ⫾ 9.8 12.7 ⫾ 2.1 29.9 ⫾ 6.2 89.6 ⫾ 12.8 29.2 ⫾ 3.9 16.3 ⫾ 5.0
.37 .98 .38 .61 .43 .58
2 3 6 3 1
2 3 7 4 0
LVEF, Left ventricular ejection fraction; body mass index, [weight (kg) ⫼ height (m2)].
subject required a fourth test. Results used for analysis were taken from the baseline test with the highest peak oxygen uptake value. During the first 6 weeks of exercise training, work intensity averaged 59 ⫾ 13% of the oxygen uptake reserve. During weeks 7 through 12, work intensity increased to 73 ⫾ 19% and 81 ⫾ 21% during weeks 13 through 24. Significant changes were observed in oxygen consumption after 12 weeks between the exercising group and non-exercising group. Oxygen uptake improved by 0.7 and 1.6 mL · kg–1 · min–1 over the 6 and 12 weeks, respectively, in the exercising group, whereas the non-exercising group declined by 0.7 and 0.8 mL · kg–1 · min–1. Differences in oxygen uptake between the 2 groups at 12 weeks was statistically significant (P ⫽ .019). Additional fitness gains were observed in those subjects that continued to exercise at 24 (P ⫽ .001) and 36 weeks (P ⫽ .14). The most common reasons for terminating the exercise test were fatigue and dyspnea. As a result of improved fitness, 4 subjects in the exercise group moved up 1 level in FAI (moderate-to-mild impairment, n ⫽ 2; marked-to-moderate impairment, n ⫽ 2), whereas, 5 subjects in the control group moved down 1 category, and 2 subjects moved up 1 category (no impairment to mild impairment, n ⫽ 1; mild-to-moderate impairment, n ⫽ 1; moderate-tomarked impairment, n ⫽ 3; marked-to-moderate impairment, n ⫽ 2).
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Quality of life When the exercising group was compared with the control group, there was a significant improvement in the perceived physical function subscale change score of the SF-36. The perception of physical functioning in the exercising group increased by 10.4 ⫾ 18.5 points (14%) from baseline to 12 weeks, whereas the control group declined by 4.7 ⫾ 12.4 points during the 12 weeks (P ⫽ .025) (see Table II). No other significant differences were observed between the groups. Subjects who continued to exercise maintained significant improvements in perceived physical function at 24 weeks (P ⫽ .04).
Symptoms from HF At 12 weeks, subjects in the exercising group (24.9 ⫾ 11.9 to 21.7 ⫾ 17.7; 13% decline, P ⫽ .50) and control group (31.9 ⫾ 18.7 to 31.8 ⫾ 20.2, P ⫽ .70) reported no change in difficulty living with their symptoms from HF. Difference in the change score on the LHFQ was not statistically significant between the 2 groups (change exercise group ⫽ –3.2 ⫾ 13.7; change control group ⫽ – 0.1 ⫾ 13.4, P ⫽ .75). Negative scores denote a perception of less difficulty in living with symptoms of HF.
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Table II SF-36 subscale change scores (⌬ ⫽ 12-week score ⫺ baseline score) for subjects in the exercise (n ⫽ 12) and control (n ⫽ 15) groups. Results (P value) of the independent t tests are also presented. Exercise group
Control group
SF-36 subscale
⌬ Score
⌬ Score
P value
Physical function General health Vitality Mental health Role physical Role emotional Social function Body pain
10.4 ⫾ 18.5 ⫺4.2 ⫾ 24.1 ⫺4.2 ⫾ 12.8 2.3 ⫾ 13.0 ⫺6.3 ⫾ 24.0 2.8 ⫾ 36.1 1.7 ⫾ 42.6 ⫺7.2 ⫾ 23.3
⫺4.7 ⫾ 12.5 0.7 ⫾ 22.9 6.7 ⫾ 21.7 1.8 ⫾ 18.8 1.7 ⫾ 24.0 2.2 ⫾ 26.6 ⫺1.3 ⫾ 25.3 3.9 ⫾ 25.4
.025 .87 .24 .68 .46 .46 .94 .14
Self-efficacy for exercise Self-efficacy for exercise was higher in the exercising group when compared with the control group (change exercise group ⫽ 7.7 ⫾ 12.0; change control group ⫽ 0.4 ⫾ 13.6, P ⫽ .10). Although the difference in the change score between the 2 groups was not statistically significant, significant within-group improvements were observed in the exercise but not the control group. Subjects in the exercising group reported improved self-efficacy after 12 weeks of training [(55.3 ⫾ 12.1 to 63.0 ⫾ 10.9, P ⫽ .10); 17% improvement], whereas there was no change in the self-efficacy score (52.5 ⫾ 16.3 to 52.9 ⫾ 14.7, P ⫽ .83) of the control group. Self-efficacy improvements were maintained for those subjects that continued to exercise at 24 (22%, P ⫽ .01) and 36 (40%, P ⫽ .06) weeks.
Activity diaries Overall activity level was not significantly increased (P ⫽ .94) when the change in kilocalories expended from baseline to 12 weeks was compared in the exercise (2231 ⫾ 382 kcal to 2426 ⫾ 751 kcal) and the control group (2269 ⫾ 893 kcal to 2395 ⫾ 648 kcal). Subjects’ compliance with completing the activity diaries was poor (57%), and we do not consider these results to best reflect true physical activity parameters.
Adherence Because 3 of 15 subjects assigned to the exercise group withdrew or were withdrawn from the study before collection of any follow-up data, baseline characteristics of the exercise group were compared
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for differences between those who were included in the analyses versus those who were not. Descriptive data follow in Table III. Those who were included in the analysis were more fit as measured by oxygen uptake (11.3 ⫾ 1.7 vs 17.8 ⫾ 5.7 mL · kg–1 · min–1, P ⫽ .03), had a higher self-efficacy for exercise (36.0 ⫾ 11 vs 55.3 ⫾ 12.1, P ⫽ .03) and had a higher level of education (10.0 ⫾ 2.0 vs 12.5 ⫾ 1.5 yr, P ⫽ .05).
DISCUSSION After 12 weeks, there was a significant difference in the change score between the exercise and control group on the physical function subscale of the SF-36. A moderate-to-large improvement in physical function was observed in the exercise group accompanied by a small decline in the control group. The present study is one of only a few studies that have demonstrated an improvement in QOL in a randomized controlled trial.13,16,17,31 Austrian investigators observed significant improvements in vitality, physical role, physical function, and social function in a group of chronic HF subjects randomized to 3 months of exercise compared with a non-exercising control group (total n ⫽ 25).13 Likewise, another group observed that feelings of disability significantly decreased and overall feelings of general well-being significantly improved after an exercise intervention in 67 subjects with HF randomized to an exercise training or control group.31 Conversely, Gottlieb et al14 observed no significant changes in QOL as measured by the SF-36 in 33 elderly subjects with HF randomized to 6 months of supervised exercise or usual activity. Most investigations of exercise and HF continue to focus on physiologic
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Table III Baseline characteristics of subjects randomized to the exercise group who completed ⬍6 weeks of the study and 6 weeks of the study
Baseline parameter
Completed < 6 wks nⴝ3
Completed > 6 wks n ⴝ 12
P value
Age (y) LVEF (%) Education (y) Comorbidity index score Oxygen uptake (mL · kg–1 · min–1) LHFQ score Self-efficacy for exercise score Physical function subscale
63 ⫾ 8 22.7 ⫾ 7.5 10.0 ⫾ 2.0 4.7 ⫾ 2.1 11.3 ⫾ 1.7 38.7 ⫾ 28.1 36.0 ⫾ 11.0 48.3 ⫾ 20.2
63 ⫾ 11 31.7 ⫾ 5.6 12.5 ⫾ 1.5 3.2 ⫾ 1.3 17.8 ⫾ 5.7 24.9 ⫾ 11.9 55.3 ⫾ 12.1 64.2 ⫾ 26.3
.95 .06 .05 .18 .03 .28 .03 .34
LVEF, Left ventricular ejection fraction; LHFQ, living with heart failure questionnaire (range ⫽ a lower score is a better score).
measures of change. It is important that perceptual measures be incorporated in clinical trials, because patients are less likely to continue with prescribed therapy unless they perceive benefits. After 12 weeks, aerobic fitness, as measured by improvements in peak oxygen consumption, increased by 9% in the exercise group and declined by 5% in the control group. On average, the subjects in the exercise group moved up 1 full classification from moderate impairment to mild impairment after aerobic training. The lower the FAI, the more reserve a person has to perform activities of daily living without excessive strain. It is concluded that the supervised conditioning program used in the present study successfully increased the aerobic fitness of the subjects in the exercise group, and this improvement was significantly greater than changes experienced by individuals in the control group. Subjects that stayed on in the exercise program continued to improve their fitness level through 6 months, increasing their oxygen uptake by an additional 7% beyond the 3-month measurements. Improvements in perceived physical function were also maintained. Although there was a slight decline in fitness at 9 months (3%), the overall oxygen uptake was still markedly greater than observed at baseline (12%). Traditional cardiac rehabilitation programs are on average limited to 3 months duration. After receiving the diagnosis of HF, establishing or reestablishing confidence in one’s ability to exercise clearly requires a rehabilitation program of sufficient duration with skilled professional supervision to overcome fear and other perceived barriers to
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engaging in a regular program of physical activity. For this chronically ill, sedentary population, longer training programs may be needed to effect sustained change. It is notable that self-efficacy for exercise continued to improve at 6 and 9 months, even as supervised exercise was tapered. A 3-day activity diary was used to collect information regarding subjects’ level of physical activity. Subjects’ compliance with completing activity diaries was poor (57%). Available data were analyzed, and no significant differences were found in activity level between the groups at baseline or 12 weeks. In addition, there were no differences in activity patterns from baseline to 12 weeks in the exercise or control groups. These findings were consistent with those of other investigators who used the Caltrac (Muscle Dynamics, Torrance, Calif) and doubly labeled water to measure energy expenditure.14 Perhaps more focused attention is needed in translating improvements in exercise capacity to a more active lifestyle. Rehabilitation programs that focus on more activities common to this age group may be more successful in translating increased fitness to increased physical activity in daily life. Also, a more robust and less burdensome method for data collection is needed. Twenty-seven (87%) of the 31 subjects who completed baseline testing and randomization completed at least 6 weeks of the study and were included in the analysis. There were 3 withdrawals in the exercise group (20%) and 1 in the control group (6%). This withdrawal rate is similar to
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those reported in previous investigations of training elderly HF subjects32 but slightly higher than those reported in comparable studies with younger subjects.14,31 Examination of baseline demographic characteristics revealed no significant differences between the exercise and the control groups on variables often used to predict exercise capacity. Those who withdrew from the exercise group, however, appeared to have a more severe illness profile than those who completed the study (see Table III). Confidence in the ability to exercise (self-efficacy) and oxygen uptake were significantly lower in subjects who withdrew from the exercise portion of the study than in those subjects in the exercise group who completed at least 6 weeks of the study. Although not statistically significant, it is notable that at baseline those who withdrew early from the study had a lower left ventricular ejection fraction. Likewise, they had higher comorbidity scores and reported more difficulty with symptoms from HF than those subjects who completed the protocol. More study is needed to develop a specific profile of patients with HF who can be expected to complete a rehabilitation program and those at risk for recidivism.
CONCLUSION A moderate-to-moderately-high intensity exercise training program is a safe and effective method for improving aerobic fitness in persons with chronic HF. Along with successful physiologic adaptations to exercise training, HF patients’ perceived physical function was significantly greater than subjects randomized to a control group. Those participating in the supervised exercise program perceived improvements in self-efficacy for exercise, whereas control subjects did not. In addition, exercise subjects reported less difficulty with symptoms from HF. Lastly, HF subjects continued to benefit from exercise training far beyond the traditional 12-week cardiac rehabilitation program.
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25. Rector TS, Kubo SH, Cohn JN. Validity of the Minnesota Living with Heart Failure Questionnaire as a measure of therapeutic response to enalapril or placebo. Am J Card 1993;71:1106-7. 26. Hickey M, Owen SV, Froman RD. Instrument development. cardiac diet and exercise self-efficacy. Nurs Res 1992;41:34751. 27. Acheson KJ, Campbell IT, Edholm OG, et al. The measure of daily energy expenditure—an evaluation of some techniques. Am J Clin Nutr 1980;33:1155-64. 28. Bouchard C, Trembley A, Leblanc C, et al. A method to assess energy expenditure in children and adults. Am J Clin Nutr 1983;37:461-7. 29. Haskell WL, Leon AS, Caspersen CJ, et al. Cardiovascular benefits and assessment of physical activity and physical fitness in adults. Med Sci Sports Exerc 1992;24:S201-20. 30. Charlson ME, Pompei P, Ales K, et al. A new method of classifying prognostic co morbidity in longitudinal studies. development and validation. J Chronic Dis 1987;40: 373-83. 31. Wielenga RP, Erdman RA, Huisveld IA, et al. Effect of exercise training on quality of life in patients with chronic heart failure. J Psychosom Res 1998;45:459-64. 32. Owen A, Croucher L. Effects of an exercise programme for elderly patients with heart failure. Eur J Heart Fail 2000;2:6570.
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