Change is in the air. Climate change, economic change, political change. In this month's issue of PTJ, we read that even our view of “variability” itself is changing. Specifically, Regina Harbourne and Nicholas Stergiou in “Movement Variability and the Use of Nonlinear Tools: Principles to Guide Physical Therapist Practice”1 argue that nonlinear measures, such as the Lyapunov exponent and approximate entropy, can reveal the “hidden structure” within the variability of data over time. These methods were developed to handle complexity and, thus, often fit well with rehabilitation research. They are, however, a bit complex themselves. To assist readers like me, the authors provide an appendix of jargon terms; multiple examples of nonlinear analysis of biological systems, including clinical studies; and a virtual case study illustrating the use of nonlinear thinking in clinical decision making. Nice. But wait, there's more. Accompanying this article is a commentary2 by Daniela Corbetta, a developmental psychologist, who provides insights from her own work on infant motor-perceptual development in support of the authors’ perspective. This article-commentary combination is exactly the “translational” information that both you, the readers, and we, the Editorial Board, desire for our Journal.
But because we’re friends, let's be honest. You may get a sinking feeling that something is amiss as you seriously consider the implications for your own work. For example, certain features of variability, rather than simply being a reflection of movement error, may reveal the very processes by which impairments might be increasing or decreasing. Interesting, but which is it—increasing, or decreasing? Changes in variability, as reflected by nonlinear analysis, might signal that movements are becoming more or less optimal. That would be valuable information—if only I knew whether it was “more” or “less.” The same pattern of change could be signaling that the time is right for more task-specific practice or more focus on impairments, more balance training or less, the addition of a modality or not. “That doesn’t make any sense,” you say.
Obviously, what's missing is interpretation—specifically, the requirement to interpret one set of results in light of all other relevant information. Interpretation is, of course, not specific to nonlinear analysis. We would interpret a change in range of motion differently depending on whether the change was associated with increases or decreases in muscle performance. Clinical interpretation is necessary, as we never have all the relevant information we would like. As Dragnet's Joe Friday might have said, the “facts,” no matter how comprehensive and clear, never really “speak for themselves,” do they? Even more important, the researchers who conduct studies don’t make clinical decisions based on data interpretation—clinicians do. The PTJ Editorial Board understands this and strives to make PTJ a consistently useful clinical tool. To this end, PTJ provides multiple sources of information to assist readers in making their own interpretation. These include:
Bottom Line summaries
Rapid Response e-letters
Journal issues focused on a single topic
There also are “hidden” features that elevate the level of interpretation and increase the impact of the articles in PTJ. The review process is one such feature and begins with a review team led by an Editorial Board member with content expertise. Paul Helders and I, for example, handle all pediatric content. Editorial Board members personally read each of their assigned manuscripts, including the multiple revisions and all the reviewers’ comments, leading up to publication. The intent here is not to micromanage or extend the review process, but rather to publish clear, concise, comprehensive, clinically focused reports. In addition to our individual duties, Editorial Board members form work groups that engage in continuous dialogue about issues ranging from the statistics available for clinical trials, to ideas for new special series topics, to how to assist authors in publishing case reports, to contacting top scientists for commentaries and perspective articles. You also see us at Annual Conference and Combined Sections Meeting, where we provide educational sessions and hold meetings to chart the future of PTJ.
In closing, I encourage reviewers, authors, and readers to communicate with the Editorial Board about your ideas on how to increase the impact of your Journal. Clinical decisions based on our interpretation of data are rarely black and white—and that won’t change—but our patients await our best interpretation, and PTJ is here to help.
- American Physical Therapy Association