BACKGROUND A systematic literature review we conducted yielded two trials investigating eccentric exercise in patients with coronary artery disease and two trials in the chronic heart failure population. Eccentric exercise was reported to be a safe form of exercise for coronary patients, causing minimal heart and breathing stress and being perceived as "fairly light" exertion. Eccentric exercise, when compared with concentric exercise (shortening contractions) resulted in comparable improvements in muscle strength and walking distance, often with reduced oxygen usage.
With no increase in negative events with coronary patients, recently eccentric exercise has been trialed in heart failure patients. One trial looked at six-minute walk test differences in patients with mild heart failure following a program of eccentric or concentric cycling. They found that although both groups improved their walking distance, the eccentric exercise was completed at lower levels of work and stable heart rates. A second trial completed eccentric exercise by descending stairs, compared with participants who climbed stairs and measured knee muscle strength. They reported that participants found the stair descending easy with significant improvements in static strength but not eccentric (lengthening) or concentric (shortening) force. Both of these studies were limited by a population of a small number (12-15) of participants primarily males, with poorly defined or mild heart failure.
RESEARCH AIMS Given the limited evidence in coronary patients and more specifically heart failure patients, this current study aims to fill knowledge gaps by looking at the effects of eccentric exercise on both males and females, with mild to moderate heart failure, of both heart failure types- systolic (heart contraction problems) and diastolic (heart relaxation problems). We aim to include measures of both function and quality of life. We will also monitor compliance and patient satisfaction with the aim of developing a safe and tolerable exercise program that is feasible for implementation in heart failure rehabilitation programs.
METHODS Participants will be recruited through The Northern Hospital heart failure outpatient medical clinics and also through referral to the current rehabilitation program following inpatient admission or G.P referral. This study will be a prospective, three-armed, parallel-design, randomised controlled trial with a 1:1:1 ratio. A separate randomisation procedure will be prepared for each of the three included New York heart association heart failure classes so that disease severity will not affect the results.
As well as the primary outcomes of walking capacity and quality of life, secondary outcomes will include lower limb strength and levels of fatigue. We will also monitor adherence, attendance, pain, and any adverse events occurring in any session.
Demographic and outcome data will be analysed for between group differences at baseline. To determine whether group 1 improved more than groups 2 and 3 immediately after the 8-week program, data will be analysed with analysis of covariance using the baseline measures as covariates. Categorical outcome variables (death or hospital admission) will be analysed with relative risk ratios. To avoid bias and to maximise the randomisation process, intention to treat analysis will be utilised. Participants withdrawing from the project will be followed up where possible. Where data are missing, the carry forward technique will be used, which assumes that missing data remain constant. Finally, correlations between the secondary outcome variables and the primary outcome variables will also be examined to detect where associations exist as well as associations between outcomes and types of heart failure (systolic or diastolic). Significance level of P\<.05 will be used for hypotheses testing.
