Exercise as it relates to Disease/Can Resistance Training Improve Skeletal Muscle Health for People Who Suffer From Chronic Heart Failure?

This is an analysis of the research article ‘Randomised trial of progressive resistance training to counteract the myopathy of chronic heart failure’ written by Charles T.PU, et al.

What is the background of this research?

Chronic heart failure (CHF) is a term used to describe a condition of the heart where the ventricles ability to fill with or eject blood is impaired. This can be caused by any structural or functional cardiac disorder. The cardinal sign of CHF is exercise intolerance, shown through fatigue and dyspnoea during minimal activity.

Previous research suggests that peripheral skeletal muscle abnormalities largely explain the exercise intolerance associated with CHF. These abnormalities include a skeletal muscle myopathy distinguished by preferential loss and atrophy of type 1 fibres, decreased oxidative enzyme capacity and mitochondrial volume density as well as reduced muscle endurance, strength, power and overall exercise tolerance.

Peripheral skeletal muscle adaptations in younger CHF patients have been proven in three previous uncontrolled and nonrandomised studies that have used a nonaerobic exercise modality. Aerobic exercise interventions have been proven tolerable in young to middle-aged patients with stable CHF. This intervention has led to improved exercise capacity, however no peripheral muscle adaptations have been reported. Due to limited research on women and patients over 70 years of age, suggestions have been made that improvements seen in younger CHF patients, after these training types, may not extend to the older CHF population.

Researchers chose to investigate whether progressive resistance training could be used as multi-faceted intervention to counteract the myopathy of chronic heart failure as well as improve the exercise capacity of elderly women with CHF.

Where is the research from?

This research was a collaborative effort between eight researchers from the Nutrition, Exercise Physiology, and Sarcopenia Laboratory, Jean Mayer United States Department of Agriculture, Human Nutrition Research Centre on Aging, Tufts University, Boston 02111; Brockton West Roxbury Veterans Affairs Medical Centre, Division on Aging, Harvard Medical School, Boston; Hebrew Rehabilitation Centre for Aged, Division on Aging, Harvard Medical School, Boston; Department of Health Sciences, Sargeant College of Health Rehabilitation Sciences, and Department of Cardiology, Boston University, and Gerontology Division, Beth Israel Deaconess Hospital, Boston, Massachusetts; and School of Exercise and Sport Science, University of Sydney, Sydney, Australia.

The American Physiological Society published this article in the Journal of Applied Physiology on the first of June 2001. What kind of research was this?

As there were two initial hypotheses, the research was done in two parts. Firstly, a cross sectional comparison was carried out to compare elderly female patients with CHF to diseased females with no trace of CHF.

The second round of research was a randomized controlled clinical trial which was carried out to determine the efficacy of high-intensity progressive resistance training in older patients with CHF.

What did the research involve?

The purpose of this study was to find out if high-intensity progressive resistance training would be well tolerated, improve impaired skeletal muscle characteristics as well as overall exercise performance in elderly women with CHF. 16 female patients, 65 years or older with mild to moderate stable CHF, were compared with 80 age-matched diseased females without CHF. This was to test whether the muscle function of these elderly patients would be more impaired than their aerobic capacity when compared to other diseased populations.

The CHF cohort were then randomised to progressive resistance training or control stretching exercises for 10 weeks.

Progressive resistance training group -

Patients in this group participated in high-intensity resistance training, 3 days a week for 10 weeks. This type of training was performed at 80% 1 RM (the repetition maximum that could be lifted in good form), where strength was retested every 10th session to determine a new 1 RM. A variety of dynamic contraction exercises were performed on assisted weight machines. Three sets of eight repetitions were completed on each machine, with each repetition lasting 6–9 seconds with a 2 second rest in between. 60 to 90 seconds rest was given between sets and 1–3 minutes rest as needed between each machine. Sessions were approximately 60 minutes duration with a two minute walking or cycling warm up and a five minute stretching cool down.

Placebo control group -

Patients in this group participated in low-intensity stretching exercises without resistance, 2 days a week for 10 weeks. The session lasted for an hour and focused on stretching exercises of the neck, trunk and extremities.

What were the basic results?

There were four key findings in this study.

1)	The muscle function of this cohort was significantly impaired, however their aerobic capacity was comparable to the age-matched subjects without CHF.

2)	Progressive resistance training improved previously listed peripheral musculoskeletal abnormalities as well as overall exercise performance.

3)	Improvements in musculoskeletal performance were directly related to the improved overall exercise tolerance after training.

4)	The data of this study suggests that improvements in musculoskeletal function and overall exercise performance were through adaptations made in peripheral muscle not the result of improved resting cardiac function.

How did the researchers interpret the results?

The researchers concluded that progressive resistance training was well tolerated in this subpopulation of CHF patients. Peripheral muscle abnormalities and exercise capacity improvements were evident in this population through this training type. Researchers determined that current aerobic interventions may improve exercise capacity however it does not address the functional muscle changes that are responsible for the myopathy related to CHF. What conclusions should be taken away from this research?

Progressive resistance training does counteract the myopathy of chronic heart failure. This type of training is appropriate for older CHF patients. Resistance training is favourable in this population as the efficacy of aerobic training has not been reported. What are the implications of this research?

There are minimal implications. The researchers studied a subpopulation of CHF patients that have otherwise been ignored. The exercise modality was appropriate for this research in terms of the physiology behind resistance training and muscle gains. Progressive resistance training is easily accessible for people living in the real world, meaning this intervention is a practical form of treatment for all CHF patients.

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