Resistance exercises for patients with coronary artery disease after myocardial infarction and coronary artery bypass grafting were investigated. The authors' concluded that resistance exercise can be a safe, effective strategy in health promotion programmes for coronary patients. Due to possible error and bias in the review process and poor primary study quality the conclusions may not be reliable.

To investigate the benefits and risks of resistance exercises for patients with coronary artery disease after myocardial infarction or coronary artery bypass grafting.

MEDLINE, PEDro, Cochrane Register of Controlled Trials and CINAHL were searched between August and October 2007 for papers in Portuguese, Spanish and English. Search terms were reported. Additional searches of indexed health journals and handsearching of reference lists was also performed.

Randomised controlled trials (RCTs) of patients older than 45 years with coronary artery disease who suffered myocardial infarction and/or had coronary artery bypass grafting were eligible for inclusion if they applied resistance exercises in the cardiac rehabilitation process with or without another exercise mode. Studies of coronary artery disease patients who underwent other surgical operations and that focused solely on exercises other than resistance exercises in rehabilitation were excluded.

The proportion of males in the included studies ranged from 0 to 100%. Most studies had participants with an average age under 60 years. All interventions were supervised, less than three to nine months duration and were reported were performed between three and nine months after myocardial infarction and/or coronary artery bypass grafting. Included studies used either resistance exercises only or a combination of resistance and aerobic exercises,. Most studies evaluated aerobic capacity through peak oxygen consumption (peak VO₂). Muscle strength, body composition, quality of life and acute haemodynamic effects were also evaluated.

The authors stated neither how papers were selected for the review nor how many reviewers performed the selection.

Methodological quality was assessed using the PEDro Scale (which scores aspects such as eligibility criteria, randomisation, allocation concealment, blinding and intention to treat) to give a quality score out of 10. The authors did not state how many reviewers performed the validity assessment.

Data were extracted for the outcomes using the Critical Review Form (quantitative studies). The authors stated neither how the data were extracted for the review nor how many reviewers performed the data extraction.

The studies were pooled narratively grouped by outcome. Individual study details were available in tables for examination of between-study differences.

Eleven RCTs were included (n=283). Four RCTs had a quality score of 4 out of 10, six studies scored 5 and one scored 6.

A combination of resistance and aerobic exercise was associated with improvement in aerobic capacity compared with control in six RCTs; in three this was statistically significant. One RCT found an increase in peak VO₂ in the aerobic exercise-only group compared with combined aerobic and resistance exercise. Nine RCTs reported a significant increase in muscle strength after training (type not specified). Two RCTs reported improvement in fatigue (one RCT reported improvement in further mood state parameters) with inclusion of resistance training. Two RCTs found greater improvement in activities performed at home in the resistance training group compared with control.

There was no significant difference between resistance exercise only groups and control in peak VO₂. No undesirable adverse haemodynamic effects were found in any of the RCTs.

Resistance exercise can be a safe, effective strategy in health promotion programmes for coronary patients.

The research question was supported by inclusion criteria for participants, intervention and study design, but there were none for outcomes. No attempts to search unpublished sources were reported, which increased the possibility of publication bias. Language bias was also possible as only studies published in Portuguese, Spanish and English were sought. The authors did not describe how study selection, validity assessment and data extraction were performed, so it was unknown whether steps were taken to minimise bias and error. The results were not clearly reported and the quality of the primary studies generally appeared to be poor. Due the possibility of error and bias in the review process and poor primary study quality, the authors' conclusions may not be reliable.

Practice: The authors stated that patients should be adequately assessed before rehabilitation that included resistance exercises to decrease the risk of complications. Health promotion needed to focus on activities that promoted better interaction with the patients' environment and social groups as well as favourable physiological changes.

Research: The authors did not state any implications for research.

Not stated.

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.