Introduction: In the past two years we have been conducting several overviews of physical therapy reviews. The majority of the included reviews investigated the effectiveness of exercise therapy. Although the Cochrane Handbook specifically outlines how clinical, methodological and statistical heterogeneity can be identified and addressed, we found that in these reviews it was not always clear how this was done. We also noticed inconsistencies in addressing heterogeneity between Review Groups. The goal of this methodological study is to put our findings in a broader perspective and to systematically investigate the methods used regarding clinical, methodological and statistical heterogeneity in reviews within the field of exercise therapy. Objectives: To assess differences in methods used to address heterogeneity when considering a meta-analysis between in Cochrane reviews and between review groups and assess to what extend the used methods conform to the methods described in the handbook. Method: The Cochrane Library will be searched from 2008 to August 2010 for reviews using the following search terms: exercise OR exercise therapy. Published reviews restricted to exercise interventions will be included. The protocols of the included reviews will be recovered in Archie. Two reviewers will independently select reviews and extract data. A data extraction form will be used that includes the items described in the handbook regarding different types of heterogeneity, such as: identify inconsistency of results (visual or statistical tests), unit of analysis, pre-specified sensitivity analysis, using fixed or random effects meta-analysis, effect measures (mean difference or standardized mean difference), exclude studies from analysis. The extracted data will be categorised per review group. Differences between review groups and handbook methods will be described and discussed. Results: The results will support development of more consistency between review groups and further development of methods in meta-analyses to maintain the high quality of Cochrane reviews.