Exercise as it relates to Disease/Effect of resistance training on physical disability in chronic heart failure

This is a critique of the research article: Savage, Patrick A et al, "Effect of resistance training on training on disability in chronic heart failure." Medicine and science in sports and exercise vol. 43, 8 (2011): 1379-86. doi:10.1249/MSS.0b013e31820eeea1

What is the Background of this Research?

Heart failure (HF) is characterized by the heart's inability to pump an adequate supply of blood to the body. HF is a collection of symptoms that weaken the heart. When diagnosed as chronic, the symptoms are continuous and do not improve over time.

Patients with chronic heart failure (CHF) report high rates of physical disability based on their ability to perform activities of daily living. This can lead to a reduction in quality of life and an increase in health care costs.

Prior to publication, there is little research on assessing disability in CHF patients, by directly measuring performance in a range of common activities of daily living. Furthermore, there is limited evidence on the effects resistance training alone on CHF patients. Past studies have shown the benefits of aerobic training on exercise capacity, walking endurance and clinical status in CHF patients. Majority of common daily activities (lifting objects, rising from a seat, etc) are strongly dependent on muscle strength highlighting its importance for physical function.

The first aim of the study being critiqued was to compare performance in activities of daily living in CHF patients and healthy controls to evaluate the extent of physical disability and its relationship to muscle strength. The second aim was to determine the effects of 18 weeks or resistance training on muscle strength and performance on activities of daily living.

Where is the research from?

The research article being critiqued was published in the journal of Medicine & Science in Sports & Exercise (MSSE). MSSE is a leading peer-reviewed multidisciplinary journal featuring investigations, clinical studies and comprehensive reviews on topics in sports medicine and exercise science.

A total of seven authors contributed to the article whom were all associated with the University of Vermont (College of Medicine), in departments of medicine, and molecular physiology and biophysics.

The lead Author, Patrick Savage, is associated with 100+ publications and has expertise in health and disease topics such as physical activity and cardiovascular.

What kind of research was this?

The method of research is a quasi-experimental design, as the aim of the study is to identify and compare the impact of the resistance training intervention on the patient and control groups. This type of method is effective for estimating the effects of an intervention, when there limited possibility to randomize. To increase accuracy the control group is constructed as similar as possible to the treatment group.

A limitation of this study design is the increased need for assumptions to be made about the control group. Without randomisation, it can be difficult to verify that all confounding variables have been accounted for. This method of approach also requires a larger number of subjects in both groups in comparison to experimental. This has not been demonstrated in this study.

What did the research involve?

Patients and controls were assessed for performance in activities of daily living, self-reported physical function, peak aerobic capacity and muscle strength before and after an 18 week resistance training program.

The resistance program occurred 3 x per week with gradual progression of volume and intensity. The physical function performance test-10 (PFP-10) was used to assess functional ability on ordinary activities of daily life. PFP-10 has been validated over past studies on assessing physical performance in older cardiac patients. The Medical Outcomes Study Short-Form-36 (MOS SF-36) was used to assess self reported physical function and quality of life. This method has also been validated for CHF patients.

The CHF patients and control participants that completed the trial were recruited each following a independent criteria. The control group was constructed to display similar activity levels as the CHF patients to limit any confounding effects of the several disease related factors. Participant recruitment followed a rigorous selection criteria that although lowered the number of participants, which can be seen as a limitation, allowed the reduction of confounding factors.

What were the basic results?

Main Findings:

		Composite 1 RM (kg)	Total PFP-10 Score	MOS SF-36
Control	Pre:	271$\pm$35	69.6$\pm$3.9	82.3$\pm$5.3
	Post:	361$\pm$40	73.5$\pm$4.2	90.0$\pm$1.9
CHF	Pre:	248 $\pm$46	48.5$\pm$6.9	62$\pm$5.7
	Post:	333$\pm$58	53.9 $\pm$6.8	67.0$\pm$6.2

Major findings:

• Resistance training resulted in significant improvement in composite 1 RM for both groups. CHF patients displayed a greater increase in fat free mass suggesting increased muscle growth.
• Total PFP-10 score improved in both training groups as a result of improvements in upper and lower body strength.
• There was also minor improvements in overall self reported physical function.

Baseline results showed that CHF patients and control participants had similar levels of muscular strength. Although, CHF patients displayed significantly lower physical performance and function scores demonstrating the impaired physiological capacity to perform activities of daily living.

What conclusions can we take from this research?

This study has effectively proven that resistance training is an effective intervention for the enhancement of muscle strength and performance in activities of daily living. Improvements in PFP-10 and MOS SF-36 scores demonstrates the relationship between muscle weakness and physical disability in CHF patients.

These findings are similar to recent studies on resistance training for CHF patients, suggesting that when done safe and effectively, is an effective intervention for reversing muscle mass and improving overall quality of life.

Practical advice

For clinical perspective results suggest that further interventions designed to lessen physical disability in CHF patients should consider improving muscle strength. Although, this research fails to provide recommendations on safe and effective training. Further information and resources may need to be examined for practical advice on health and safety guidance. Additionally, new evidence suggests that this type of training is to be supplemented with aerobic exercise for maximum physical function improvements.

Further information/resources

• Exercise and Chronic Heart Failure
• Living Well with Heart Failure
• Resistance Exercise Guidelines for Persons With Physical Disabilities
• Resistance Versus Aerobic Exercise Training in Chronic Heart Failure
• Resistance Exercise Training in Patients with Heart Failure