Review of the Effects of Resistance Training in Patients with Chronic Heart Failure: Potential Effects Upon the Muscle Hypothesis Lawrence P Cahalin, PT, MA, CCS;' Daniel C. Ferreira, SPT;' Sumio Yamada, PT, PhD;^ Paul K. Canavan, PT, PhD'
'Northeastern University, Department of Physical Therapy ^Nagoya University, Faculty of Medicine, Department of Health Sciences, Nagoya, Japan
ABSTRACT
Resistance training (RT) has been proposed as a potential management technique for persons with congestive heart failure (CHF) with the possibility of improving the vicious CHF cycle of pump failure, neuroendocrine abnormalities, skeletal muscle myopathies, dyspnea, fatigue, increased ventilation, and increased sympathetic nervous system activity (the Muscle Hypothesis of CHF). However, very little research has examined the effects of RT in persons with CHF or the effects of RT on the Muscle Hypothesis. The purposes of this paper are to describe the long-term effects of RT in persons with CHF and attempt to describe how these effects will impact the Muscle Hypothesis of CHF. A Medline search of English articles on RT in CHF was performed with the following keywords: resistance training, strength training, weight training, resistance exercise, heart failure, and muscle hypothesis. The references of published articles were further reviewed for additional articles pertaining to RT in CHF and the potential effects on the Muscle Hypothesis. Inclusion criteria for this review were studies of RT alone or RT with aerobic exercise (AE) in persons with CHF. Three review articles and 24 studies of RT were found of which 6 studies examined RT alone, 7 studies examined RT with short bouts of AE (< 5 minutes of continuous AE), and 11 studies examined the effects of RT combined with long bouts of AE. The results of these studies revealed significant improvements in muscle strength and endurance, peak oxygen consumption, forearm blood flow, left ventricular function, and quality of life with very few complications from RT. Differences in the methods of RT were found which likely affected the observed results. Chronic RT alone or with AE appears to favorably influence many aspects of the muscle hypothesis of chronic CHF. The improvements in skeletal muscle strength and endurance, peak oxygen consumption, forearm blood flow, left ventricular function, and quality of life in persons with
Address correspondence to: Lawrence P. Cahalin, PT, MA, CCS, Northeastern University, Department of Physical Therapy 6 Robinson Hall, Boston, MA 02115 (
[email protected]).
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CHF suggest that RT prescribed alone or with AE can be done safely and has favorable effects on the CHF Muscle Hypothesis. Further examination of isolated RT and RT with short versus long bouts of AE is needed. Key Words: circuit training, strength training, weight training, skeletal muscle, left ventricular dysfunction INTRODUCTION The American Heart Association recommends that resistance training (RT) be provided to healthy persons and low risk cardiac patients, but not to moderate-to-high risk cardiac patients, like those with chronic heart failure (CHF).^ However, several recent articles reviewing RT in CHF found RT to be safe and effective for patients with CHF.^'' Although these recent literature reviews were published in the past year, the reviews did not include all available literature of RT in persons with CHF and lacked a complete description and discussion of the training methods and implications of the RT used in the studies.^" A more complete description and discussion of the training methods and implications should help therapists and other health professionals prescribe RT for persons with CHF. The effectiveness of RT may also be studied by considering the potential training benefits of this approach on the Muscle Hypothesis of CHF. The Muscle Hypothesis of CHF was first illustrated by Coats et al to better describe the vicious cycle of CHF (Figure 1).^ The Muscle Hypothesis proposes that an initial reduction in left ventricular function and resultant inactivity stimulates the release of tumor necrosis factors which activates catabolic factors that cause skeletal myopathy. Skeletal muscle myopathy and abnormal skeletal muscle function in persons with CHF results in greater activation of muscle ergoreceptors and a subsequent increase in ventilation and sympathetic nervous system excitation. Increased sympathetic activity increases peripheral vasoconstriction and afterload which reduces peripheral blood flow and further impairs skeletal muscle function all of which worsens left ventricle function and promotes the vicious cycle of chronic CHF (Figure 1).^"^ It has been suggested that exercise can alter this cycle by: (1) increasing functional activities and exercise tolerance, (2) decreasing the release of tumor necrosis factor, (3)
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improving metabolic systems with the potential to induce an anabolic state, (4) improving and possibly preventing skeletal muscle abnormalities, (5) decreasing the dyspnea and fatigue associated with chronic CHF, (6) decreasing sympathetic activation with subsequent decrease in vasoconstriction and afterload, and (7) increasing peripheral blood flow, all of which have the potential to improve cardiac pumping.^"" In view of the above, the purposes of this paper are to provide: (1) an updated literature review by adding several recent studies of RT, (2) a more complete description and discussion of the methods of RT used in the available literature, (3) an overview of the potential effects of RT upon the Muscle Hypothesis of CHF,'-" and (4) several methods to facilitate RT efforts in persons with CHF. The RT studies will be categorized as: (1) RT alone or with short bouts of aerobic exercise (< 5 minutes) and (2) RT combined with longer bouts of aerobic exercise (mean ± SD duration of 26 ± 12 minutes) in persons with CHF. METHODS A Medline search of English articles on RT in CHF was performed with the following keywords: resistance training, strength training, weight training, resistance exercise, heart failure, and muscle hypothesis. The references of published articles were further reviewed for additional articles pertaining to RT in CHF and the potential effects on
LV Dysfunction
Vasoconstriction Increased Afterload
Reduced Peripheral Blood Flow
I
Sympatho-Excitation Vagal-withdrawal
the Muscle Hypothesis. Inclusion criteria for this review were studies of RT alone or RT with aerobic exercise (AE) in persons with CHF. Three review articles and 24 studies of RT were found of which 6 studies examined RT alone, 7 studies examined RT with short bouts of AE (< 5 minutes of continuous AE), and 11 studies examined the effects of RT combined with long bouts of AE. RESULTS OF REVIEW Effects of Resistance Training in Heart Failure
Table 1 shows the 13 studies of RT alone or combined with short duration AE^"^' and Table 2 shows the 11 studies of RT with longer duration AE.^"^ Tables 1 and 2 also list the methods and effects of theses training regimens as well as the locations within the muscle hypothesis where beneficial effects are likely to occur. It is apparent from Tables 1 and 2 that RT has the potential to reduce the disability of chronic CHF by favorably modifying: (1) the ergoreflex response, (2) tumor necrosis factor levels, (3) the anabolic state associated with CHF, (4) peripheral blood flow, and (5) muscle fiber type as well as muscle strength and endurance."^ The majority of the reviewed studies improved skeletal muscle strength'""" 19,21,22,26,27,29-32 gp^j 7 gf {[^g studies f o u n d
improvements
in skeletal muscle endurance.'"''^"'^'^^-^' These improvements may favorably alter the catabolic state of skeletal muscle.^"^ Four studies of RT with short bouts of AE
TNF, Insulin Resistance Malnutrition, Inactivity
Catabolic State
I
Skeletal and Respiratory Myopathy
Increased Ergoreceptor Activity Muscle Fatigue
Increased Ventilation
Dyspnea
Figure I.The muscle hypothesis of chronic heart failure. In this hypothesis an initial reduction in left ventricular function activates catabolic and reduces anabolic factors that cause skeletal myopathy. This in turn leads to exercise intolerance and sympathoexcitation that, through the combined effects of a persistent catabolic state and of profound inactivity, further worsen skeletal muscle structure and function, and may eventually lead to a progressive effect on remodelling of the left ventricle. Reprinted with permission from BMJ Publishing Group. Br Heart J. 1194;72:536-539. Copyright 1994, BMJ publishing Group.
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Table 1 . Resistance Training Alone or Combined with Short-Duration Aerobic Exercise Study
Sample Size and Characteristics
Design
Intervention
Clinically Significant or Statistically Significant Outcomes
Kochetal.'
Exercise Croup N= 25 (19 men, 6 women) Age: 55+10 years Ejection Eraction: 26+11% Peal
