2.1 | Study selectionStudies included were randomised controlled trials comparing the effect of resistance exercise on the exercise ability of COPD subjects.Only human studies in the English language were considered. Inclusion was not limited by study size or publication type. Publications excluded were review articles and commentary and studies that did not deliver a measure of an association. Figure 1 shows the whole study process.The articles were integrated into the meta-analysis when the following inclusion criteria were met:1. The study was a randomised controlled trial.2. The target population is COPD subjects.3. The intervention programme was to investigate the outcomes of the resistance exercise on the exercise ability.4. The study included comparisons between resistance training COPD subjects and non-resistance training control COPD subjects.