Challenges inherent to t'ai chi research: part II-defining the intervention and optimal study design.

Although a growing body of clinical research has begun to evaluate the efficacy and safety of t'ai chi as a therapeutic tool for a variety of health conditions, little attention has been devoted to evaluating "how" t'ai chi is scientifically studied, and the advantages or limitations of different methodological approaches. In a companion to this paper (Part I), we argued that t'ai chi is a complex, multicomponent intervention, which poses unique challenges regarding the distinction of specific versus nonspecific effects and limitations regarding the use of reductionistic research frameworks. In this second, companion paper, we discuss additional obstacles inherent in precisely defining the t'ai chi intervention in an experimental paradigm. These challenges include t'ai chi's pluralism, the concept of t'ai chi dosage, and long- versus short-term evaluations of t'ai chi's efficacy and safety. To address these challenges, and with a goal to provide complete and unbiased evidence, we propose a pluralistic methodological approach to clinical research that includes controlled randomized trials of fixed protocols, community-based pragmatic trials, cross-sectional studies of long-term practitioners, and studies that integrate qualitative methods.