Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> I. INTRODUCTION <s> Digital Technology is constantly improving as information becomes wireless. These advances demand more wearable and mobile form factors for products that access information. A product that is wearable should have wearability. This paper explores the concept of dynamic wearability, through design research. Wearability is defined as the interaction between the human body and the wearable object. Dynamic wearability extends that definition to include the human body in motion. Our research has been to locate, understand, and define the spaces on the human body where solid and flexible forms can rest-without interfering with fluid human movement. The result is a set of design guidelines embodied in a set of wearable forms. These wearable forms describe the three dimensional spaces on the body best suited for comfortable and unobtrusive wearability by design. <s> BIB001 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> I. INTRODUCTION <s> A review of prior, relevant literature is an essential feature of any academic project. An effective review creates a firm foundation for advancing knowledge. It facilitates theory development, closes areas where a plethora of research exists, and uncovers areas where research is needed. <s> BIB002 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> I. INTRODUCTION <s> The recent maturity of body sensor networks has enabled a wide range of applications in sports, well-being and healthcare. In this paper, we hypothesise that a single unobtrusive head-worn inertial sensor can be used to infer certain biomotion details of specific swimming techniques. The sensor, weighing only seven grams is mounted on the swimmer's goggles, limiting the disturbance to a minimum. Features extracted from the recorded acceleration such as the pitch and roll angles allow to recognise the type of stroke, as well as basic biomotion indices. The system proposed represents a non-intrusive, practical deployment of wearable sensors for swimming performance monitoring. <s> BIB003 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> I. INTRODUCTION <s> Wireless body sensor networks (BSNs) possess enormous potential for changing people's daily lives. They can enhance many human-centered application domains such as m-Health, sport and wellness, and human-centered applications that involve physical/virtual social interactions. However, there are still challenging issues that limit their wide diffusion in real life: primarily, the programming complexity of these systems, due to the lack of high-level software abstractions, and the hardware constraints of wearable devices. In contrast with low-level programming and general-purpose middleware, domain-specific frameworks are an emerging programming paradigm designed to fulfill the lack of suitable BSN programming support with proper abstraction layers. This paper analyzes the most important requirements for an effective BSN-specific software framework, enabling efficient signal-processing applications. Specifically, we present signal processing in node environment (SPINE), an open-source programming framework, designed to support rapid and flexible prototyping and management of BSN applications. We describe how SPINE efficiently addresses the identified requirements while providing performance analysis on the most common hardware/software sensor platforms. We also report a few high-impact BSN applications that have been entirely implemented using SPINE to demonstrate practical examples of its effectiveness and flexibility. This development experience has notably led to the definition of a SPINE-based design methodology for BSN applications. Finally, lessons learned from the development of such applications and from feedback received by the SPINE community are discussed. <s> BIB004 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> I. INTRODUCTION <s> Providing accurate and opportune information on people's activities and behaviors is one of the most important tasks in pervasive computing. Innumerable applications can be visualized, for instance, in medical, security, entertainment, and tactical scenarios. Despite human activity recognition (HAR) being an active field for more than a decade, there are still key aspects that, if addressed, would constitute a significant turn in the way people interact with mobile devices. This paper surveys the state of the art in HAR based on wearable sensors. A general architecture is first presented along with a description of the main components of any HAR system. We also propose a two-level taxonomy in accordance to the learning approach (either supervised or semi-supervised) and the response time (either offline or online). Then, the principal issues and challenges are discussed, as well as the main solutions to each one of them. Twenty eight systems are qualitatively evaluated in terms of recognition performance, energy consumption, obtrusiveness, and flexibility, among others. Finally, we present some open problems and ideas that, due to their high relevance, should be addressed in future research. <s> BIB005 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> I. INTRODUCTION <s> This paper offers guidance to conducting a rigorous literature review. We present this in the form of a five-stage process in which we use Grounded Theory as a method. We first probe the guidelines explicated by Webster and Watson, and then we show the added value of Grounded Theory for rigorously analyzing a carefully chosen set of studies; it assures solidly legitimized, in-depth analyses of empirical facts and related insights. This includes, the emergence of new themes, issues and opportunities; interrelationships and dependencies in or beyond a particular area; as well as inconsistencies. If carried out meticulously, reviewing a well-carved out piece of literature by following this guide is likely to lead to more integrated and fruitful theory emergence, something that would enrich many fields in the social sciences. <s> BIB006 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> I. INTRODUCTION <s> Sport is an area in which the number of available computing devices is growing rapidly. However, HCI has so far devoted rather little attention to the sports domain. This workshop aims to form a community around sports by gathering existing activity in the HCI domain, thus starting a discussion on what HCI can contribute to the sports domain, as well as what HCI can gain from studying sports. <s> BIB007 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> I. INTRODUCTION <s> Zero velocity updates (ZUPT) is an effective way for the foot-mounted inertial pedestrian navigation systems. For the ZUPT technique to work properly, it is necessary to correctly detect the stance phase of each gait cycle. An adaptive stance-phase detection method is proposed based solely on an inertial sensor, which deals with the measurement fluctuations in swing and stance phases differently, and applies a clustering algorithm to partition the potential gait phases into true and false clusters, thereby yielding a time threshold to eliminate the false gait phases. The roles of the detection parameters and the relationship between them are analyzed to offer some suggestions for parameter tuning. Detection performance is evaluated with multisubject experimental data collected at varying walking speeds. The evaluation results show that the proposed detection method performs well in the presence of measurement fluctuations, which can make the detection of stance phases more robust and the choice of detection parameters more flexible. <s> BIB008 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> I. INTRODUCTION <s> Many studies show that self-care technologies can support patients with chronic conditions and their carers in understanding the ill body and increasing control of their condition. However, many of these studies have largely privileged a medical perspective and thus overlooked how patients and carers integrate self-care into their daily lives and mediate their conditions through technology. In this review, we focus on how patients and carers use and experience self-care technology through a Human-Computer Interaction (HCI) lens. We analyse studies of self-care published in key HCI journals and conferences using the Grounded Theory Literature Review (GTLR) method and identify research trends and design tensions. We then draw out opportunities for advancing HCI research in self-care, namely, focusing further on patients' everyday life experience, considering existing collaborations in self-care, and increasing the influence on medical research and practice around self-care technology. <s> BIB009 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> I. INTRODUCTION <s> A badminton training system based on body sensor networks has been proposed. The system may recognize different badminton strokes of badminton players. A two-layer hidden Markov model (HMM) classification algorithm is proposed to recognize 14 types of badminton strokes. In the first layer, we use acceleration magnitude of the right wrist to determine a threshold to detect strokes, and then, the HMM is applied to filter out nonstroke motions. In the second layer, we adopt the HMM to classify all the strokes into 14 categories. Experimental results show that the two-layer HMM can achieve good recognition accuracy. The effectiveness and feasibility of the two-layer HMM classification algorithm have been verified in a comparison. <s> BIB010 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> I. INTRODUCTION <s> This paper presents a monitoring system (Canoe-Sense) for canoe motion based on wearable Body Sensor Networks (BSNs). An effective motion segmentation method was applied to competitive sport, which can segment human motion phases automatically based on raw time series data that was acquired through wearable Inertial Measurement Units (IMUs). Orientation estimation algorithm was adopted to measure the attitude information of athletes' stroke motion of the canoe. By fusing the data of motion phases and attitude changes, the monitoring data may provide coach with a new performance monitoring method for improving coordination motions of two partners or adjusting the training plan in time. The experimental results showed that our system is able to simultaneously monitor motion phases and attitude changes of two athletes during training on the water. <s> BIB011 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> I. INTRODUCTION <s> Arm motion timing is critical during basketball shooting. This study used a body-worn, sensorized basketball sleeve to identify arm motion timing characteristics during basketball free throw and jump shot shooting for trained and novice shooters. Current basketball shooting research has typically focused on arm kinematic angles, while shot timing has received comparatively less attention. An experiment was conducted to compare arm motion timing between trained and novice shooters while shooting free throws, and a second experiment compared arm motion timing between free throws and jump shots by trained shooters. Trained shooters shot free throws significantly faster than novice shooters, and trained shooters shot jump shots significantly faster than free throws at the same distance from the basket. Knowledge of arm motion timing characteristics from this study could enable future training for improved shooter accuracy. <s> BIB012 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> I. INTRODUCTION <s> A correct riding posture is essential for a good performance in equestrian. This paper proposes a method of equestrian analysis based on body sensor networks. First of all, raw sensor data corresponding to professional (PRO) riders and beginners (BEGs) under different horse gaits were collected by inertial sensor nodes. Then, after an initial sensor alignment with the reduced error, a kind of motion reconstruction method based on the gradient descent method was used to fuse the sensor data to constantly update the rider’s attitude information. In addition, to evaluate the tracking accuracy of joint angle, an Northern Digital optical system was deployed to verify the accuracy of our method. Using the attitude information, the motions of riders in equestrian sports were reconstructed by combining the method of human kinematics. Finally, in view of the two aspects of exercise intensity and joint angle, a quantitative analysis of key features between PRO and BEG in walking and rising trot was carried out by combining with the kinematic analysis method. Experiments conducted in this paper demonstrate that the estimation errors are well controlled, and our method can better reflect the similarities and differences between PRO and BEG in equestrian sports and provide quantitative data for equestrian coaches or riders, which can be used to improve the riding skills of riders. <s> BIB013
S PORTS provides interesting opportunities for interactive technologies  . The market of wearable devices for sports is currently booming, driven by sport watches (e.g., Suunto, Garmin, Polar), sports apparel (e.g., Nike), IT (e.g., Apple), and emergent wearable products (e.g., Jawbone) manufacturers and companies. The increasing diffusion of these kinds of devices, on the one hand, is the result of the progressive miniaturization of sensors and the consequent improvement of their wearability, a term that refers to the ability of an artifact to be worn on the human body and to adapt to its shape BIB001 . On the other hand, it is due to the advancements in research on body sensor networks BIB004 and human activity recognition using wearable sensors BIB005 - BIB008 , which allowed for the collection of accurate information on people's activities and behaviors. This enabled athletes to continuously monitor a variety of parameters in sports as diverse as horse riding BIB013 , badminton BIB010 , basketball BIB012 , rowing BIB011 , and swimming BIB003 . As wearables for sports are being used by a growing user base, academic research has started focusing on the "human aspects" of such technologies, in order to understand their impacts on athletes' performances and develop more effective ways of interaction. In particular, the human-computer interaction (HCI) community has showed an increasing interest in studying wearables in the sports domain BIB007 : athletes have idiosyncratic needs that have to be understood in depth in order to create technologies capable of being integrated into their situated practices. Considering the increasing number of HCI studies on wearables for sports, we deem timely to conduct a literature review of this research domain, as reviews are critical to strengthening a field of study BIB002 . In doing so, we aim to map the topics that have been investigated and the research methods that have been adopted so far, focusing on the human side of interaction. Moreover, we want to start delineating what future strands of research could be undertaken by the HCI community. Following similar works in the HCI field BIB009 , we adopted the grounded theory for literature review (GTLR) method BIB006 , in which reviewing becomes a rigorous process of searching, selecting, and analyzing studies. Our analysis identifies five relevant themes across the selected papers. The first theme concerns the research perspective, which can be driven by a specific technological opportunity, by a design intent, or by the need to understand how a wearable device can be integrated into situated practices. The second theme relates to the type of sports and sportspeople, highlighting the predominance of individual sports, as well as the focus on a "generic" kind of athlete. The third theme explores the roles that wearables play in sport, that is enabling, improving, or augmenting the sports experience, whereby each role may affect either the physical, cognitive, or social dimension of such experience. The fourth theme addresses wearability, highlighting that current research mostly leverages wrist-worn technologies. The last theme concerns the type of feedback given to the user: in the majority of cases, a real-time feedback is given to athletes or coaches. The analysis of these themes may suggest future directions for research, by deepening and at the same time widening the research focus on wearables for sports: most of the papers we reviewed present preliminary studies from a HCI perspective, as the number of users involved 2168-2291 © 2019 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information. is limited, and attention is paid more to technology than to human needs. Given these premises, we delineated six directions for evolving HCI research in this area. In sum, this review contributes to the HCI field by surfacing a tentative map of HCI studies on wearables for sports, from their first appearance to 2018, and by identifying possible future directions of research based on the gaps identified. This paper is organized as follows: Section II outlines the methodology used. Section III presents the themes identified during the analysis, while Section IV discusses the findings and proposes lines of research to be developed in the future.