Thirty-nine years ago, Bain and Poindexter (1981) implored higher educators of kinesiology to develop curricula that prepare students to use what they learn in practical ways. Lay resource material, however, often fails to meet metrics for adequate-to-optimal readability, regardless of who produces them. Research suggests that many people trained in kinesiology are not trained to communicate its content to lay adult audiences. Thus, the purpose of this study was to advance knowledge about this academic-practice-divide in kinesiology concerning plain language communication. Methodology for a critical interpretive synthesis was used to qualitatively synthesize readability research in kinesiology. Twenty-four peer-reviewed research articles met the study inclusion criteria, all published between 1992 and 2020 (M = 2010.1, SD = 8.8). There were 1550 materials studied across the articles. It was typical for these materials to run counter to plain language guidelines (i.e., low readability in one-or-more critical areas). Most materials were unsuitable for adults with basic health literacy or less -- about half of the U.S. adult population. Following their presentation of results, the article authors often suggested one of six ways for improving lay material readability. Two major themes emerged from the qualitative synthesis of the articles: (a) how article authors discussed readability issues and what they proposed to be done to fix them, and (b) critiques of the research articles included in this study. The findings of this literature review shine light on the "need" to use readability research in kinesiology in programs that train people in an area of the discipline. [Paper presented at the National Association for Kinesiology in Higher Education Hally Beth Poindexter Young Scholar Address (2021).]