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The "impact factor" for a journal, as defined by the Institute for Scientific Information (ISI), is a measure of the frequency with which the average article in a journal is cited. The window period during which citations are counted is 2 years. For example, the impact factor for the Journal of Applied Physiology in 1999 is calculated by counting the total number of citations in 1999 to articles published in the Journal of Applied Physiology between 1997 and 1998 and then dividing this by the total number of articles published in the Journal during that 2-year period (1997-1998). This 2-year time frame is of particular importance in a field of research like physiology, in which experiments in complex human and animal models take a long time to complete. The 2-year impact factor really favors research that takes less time to complete, and it penalizes studies that take longer. In the past, because of the nature of the studies published in the Journal of Applied Physiology, the delay between when research was conducted and when the article was eventually published was often considerable. One positive step that the Editors have taken to partially offset such long delays in publication is to dramatically reduce the review time. The average time to first decision for the Journal of Applied Physiology is presently ~22 days.

A major goal of the Editorial Board of the Journal is to attract the highest quality papers. Unfortunately, it is not uncommon for authors to consider only the impact factor of a journal when deciding where to submit their papers. This is being driven by the fact that many in the scientific community use the impact factor in decisions regarding funding allocation, promotions, and tenure. The use of the impact factor as the only measurement tool of a journal discounts other very important aspects of the journal. One could easily argue that a more important measure of the impact of a journal is its "cited half-life," as this measure provides an index of the longevity or staying power of an article. ISI defines cited half-life as the number of publication years from the current year that accounts for 50% of current citations received. Therefore, the Editorial Board for the Journal of Applied Physiology would like to suggest that it is far more important for authors and others to consider the cited half-life of a journal, as this will provide an estimate of how long an article will continue to impact the literature. With a cited half-life of 9.8 years, the Journal of Applied Physiology ranks very near the top among physiological journals.

Papers published in the Journal of Applied Physiology have had and will continue to have substantial impact on biomedical science, both basic and clinical. However, until the scientific community rejects the impact factor as the single measurement of overall value, we have to live with the potential misuse of this index. Therefore, the Editorial Board and I will become more proactive in improving the impact factor of the Journal.

There are a number of different ways in which the impact factor of the Journal can be improved. If it is assumed that the total number of papers published in a given year will remain approximately the same, the impact factor can be improved only by increasing the number of citations to the papers published. One obvious way to accomplish this is to improve the quality of the papers published. As mentioned above, we will continue to emphasize publication of the highest quality papers, particularly those making novel and substantial contributions to the literature. For example, in this issue, we introduce a new category entitled "Cutting-Edge Reports," which emphasizes outstanding papers that were identified through the review process as having the potential for substantial impact in the area of applied physiology. To continue in identifying the highest quality papers, we must rely on the efforts of our outstanding reviewers and support and encourage the rigorous and consistent review of papers. Currently, our acceptance rate is at 42%, and we will continue to maintain and even lower this acceptance rate, thereby ensuring that only papers of the highest quality will be published.

Journals that have a narrow scope and a small target audience generally have lower impact factors. Conversely, a higher impact factor may simply reflect a larger audience. Therefore, another way to improve the impact factor of the Journal is to expand its scope to target a broader audience. In this respect, we have been proactive, expanding the focus of the Journal through the Highlighted Topics series and the associated calls for papers. We have also encouraged the submission of manuscripts that utilize new techniques in applied physiology, for example, those using genetic and molecular biology. By these proactive steps, we are trying to make the Journal of Applied Physiology the home for a broader audience interested in high-quality translational research in applied physiology. So far, these steps have been successful, as we have experienced a 31% increase in manuscript submissions since the initiation of the Highlighted Topics series in January 2000.

The authors themselves can also affect the impact factor by increasing the probability that their paper can be found and accessed in computer searches. Words and phrases used throughout the entire abstract and title of an article become the key for finding any article in an online database search of the literature. Selection of words and phrases thus is critical to ensuring that an article is found and, more importantly, referenced in future publications. Slight changes in terminology can tremendously affect the outcome of a computer search. For example, when searching MEDLINE from 1966 to present, the term "leg blood flow" yields ~5,630 articles, whereas a closely related term, "muscle blood flow" yields over 14,000 articles. It is clear that slight alterations in the use of words and phrases can dramatically enhance the probability that a paper can be found and accessed by fellow scientists. The Editorial Board and I would strongly encourage authors to more carefully consider their use of words and phrases in the title and abstract of their manuscripts.

Recently, there has been a major change in the Journal of Applied Physiology as well as other American Physiological Society journals with regard to the limitation on the number of citations used. Previously, authors were limited to 30 citations per article. This limitation no longer exists! This is excellent news for authors as they can now cite all relevant literature pertaining to their study. There is a long-standing tradition by authors contributing to the Journal of citing original observations, some of which date back more than 10 years. This clearly contributes to the outstanding longevity (cited half-life) of the Journal. In the past, the citation of original observations coupled with the limit on the number of citations prevented references of more recent work, even though these studies may have been relevant and important. Ultimately, the omission of citations to the most recent work in an area has a profound negative effect on the impact factor of the Journal. It is an unfortunate irony that, if all authors were to cite only two papers published by the Journal of Applied Physiology in the past 2 years, the impact factor for the Journal would increase by 1. This greatly enhanced impact factor of the Journal would, rightly or wrongly, increase the perceived impact of the articles.

All of these initiatives reflect the commitment of the Editorial Board, Associate Editors, and myself to maintaining and enhancing the outstanding reputation of the Journal of Applied Physiology so that authors will continue to be proud when their manuscripts are accepted for publication. This endeavor requires our combined efforts to accomplish a common goal, and we strongly believe that, by working together, the impact factor of the Journal can be improved.