You are presented with multiple paper abstracts, alongside the associated literature review and chapter titles. Given the provided information, you are going to do a literature review. Please generate a coherent literature review that synthesizes the content, draws connections between different works, highlights major findings, and identifies any gaps in the existing research.

Literature Review Title: Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction 
Chapter Title:  F. Improve Methodological Rigor 
1. Abstract of Cited Paper (BIB001):  Winter sports like skiing and snowboarding are often group activities. Groups of skiers and snowboarders traditionally use paper maps or board-mounted larger-scale maps near ski lifts to aid decision making: which slope to take next, where to have lunch, or what hazards to avoid when going off-piste. To enrich those static maps with personal content (e.g., pictures, prior routes taken, or hazards encountered), we developed SkiAR - a wearable augmented reality system that allows groups of skiers and snowboarders to share such content on a printed panoramic resort map. The contribution of our work is twofold: (1) we developed a system that offers a novel way to review and share personal content in situ while on the slope using a resort map; (2) we report on the results from a qualitative analysis of two user studies to inform the design and validate the usability and perceived usefulness of our prototype. 
2. Abstract of Cited Paper (BIB002):  Technological advances in wearable computing are changing the sports domain. A variety of Personal Informatics (PI) tools are starting to provide support and improve athletes’ performance in many sports. In this article, we interviewed 20 amateur and elite athletes of different disciplines, using an array of PI devices, to explore how sports, as well as athletes’ experience, are affected by such instruments. We discovered that amateur athletes present different patterns of usage compared to elite ones. Moreover, we found that elite athletes make sense of their data by exploiting the knowledge they have about their own body and sports practice. We then proposed four considerations for design that we believe should be explored in the future, to reflect on how self-tracking is changing our perspective on sports, and, by and large, on our everyday life.

Literature Review:
By looking at the methods employed across all the three identified research perspectives, most of the user studies lack thoroughness, rigor, and are not fully capable of providing in-depth insights on the "human" impact of wearables. By and large, most of the qualitative studies examined show very poor description of the methods employed and surprisingly present an incomplete recounting of the results. For example, the studies focused on requirement gathering often lack appropriate observational and ethnographic research. "Full" ethnographies implying a long period of observation and/or participation into sports activities are absent in our corpus, signaling that at present the HCI community has limited observational data on how wearables are, or can be, integrated into the sports practices. Likewise, in-the-wild evaluation studies are currently needed. Schlögl et al. BIB001 highlight that there is still a number of key problems requiring real-life user studies to be solved in order to gain a holistic understanding of the challenges that arise from interacting with wearable technology. Some of the studies claiming to be "in the field" deployed their systems in an ecological setting, but not in completely "natural" situations: For example, they introduced artificial tasks created by the researcher BIB002 or lacked rigor in explaining the study setting and the sample involved. Further, evaluations have been mainly conducted in the short term through a limited number of trials or during a limited number of days. Of course, acceptance studies are complicated by the fact that extended use might be difficult to assess with research prototypes. Indeed, all the papers in the "acceptance study" category investigate the impact of commercial wearables. The quantitative studies seem to raise the same concerns: most of them were explorative and involved a limited number of participants, with rather weak outcomes in terms of research design and statistical validity. We did not find randomized control trials among the examined papers, while questionnaires present little statistical elaboration and poor description of the used methods. Long-term impacts on psychological and behavioral variables and eventual side effects of wearable use are not considered as well. Given this, we believe that the field needs more experimental studies reporting effect size, employing longitudinal designs and involving control groups, as well as comparing different designs, with reference to the wearables' shape, wearability, functionalities, and visualizations. As for the qualitative research, researchers should focus on how wearables are used in sports practices, aiming to understand their experiential effects, the "how" and "why" they support or not the athletes' situated goals. As Rapp and Tirabeni noted, HCI research on wearable and sports lacks reports on how wearables are subjectively "lived" BIB003 , and how they are appropriated by athletes for their own situated purposes, even against the designer's intentions. Contextual interviews (like those reported in BIB003 ), diaries, and ethnographies exploring how wearable devices affect the athlete's experience, as well as how contextual factors and athletes' idiosyncrasies may influence wearables' acceptability and efficacy, should be conducted in the next years.