Trends and changes in research on the psychology of physical activity across 20 years: a quantitative analysis of 10 journals.

OBJECTIVE: To investigate content of the psychology of physical activity research over the past 20 years.
METHOD: Volumes of 10 journals, identified by impact factor and relevance to physical activity were audited every other year, during the period of 1990-2008. Inclusion criteria were studies that measured a physical activity outcome, and/or a psychological outcome as a result of physical activity. Data were extracted and coded based on 15 factors.
RESULTS: The review yielded 889 studies for analysis. Total volume of studies (from 127 in the 1990s to 762 in the 2000s), and the proportionate content space allotted to journals has increased significantly across 20 years (effect size w=0.24) (Cohen, 1992). Many study characteristics (assessment of minority/high-risk groups, self-report measurement, cross-sectional designs) have not changed. There was evidence, however, of less growth in research among older adults and young children (effect size w=0.15) compared to other age groups (effect size w=0.24), a move from pure measurement studies (effect size w=0.21) to descriptive research (effect size w=0.27), and considerable growth in environmental correlates research across time (effect size w=0.41) in the 10 journals sampled.
CONCLUSION: The behavioral science of physical activity has clearly increased in prominence and volume among the 10 journals sampled, but methodological characteristics of research could be improved in the future.