Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <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> D. Wearability <s> Ubiquitous and Wearable Computing both have the goal of pushing the computer into the background, supporting all kinds of human activities. Application areas include areas such as everyday environments (e.g. clothing, home, office), promoting new forms of creative learning via physical/virtual objects, and new tools for interactive design. In this paper, we thrust ubiquitous computing into the extremely hostile environment of the sparring ring of a martial art competition. Our system uses piezoelectric force sensors that transmit signals wirelessly to enable the detection of when a significant impact has been delivered to a competitor's body. The objective is to support the judges in scoring the sparring matches accurately, while preserving the goal of merging and blending into the background of the activity. The system therefore must take into account of the rules of the game, be responsive in real-time asynchronously, and often cope with untrained operators of the system. We present a pilot study of the finished prototype and detail our experience. <s> BIB002 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> With this work we want to illustrate new ways to assist students during sports training and to enhance their learning experience. As an example, we present the design of a wearable system intended for snowboard training on the slope. The hardware platform consists of a custom-built sensor/actuator box and a mobile phone acting as host device. These devices run algorithms for activity, context, and mistake recognition, and trigger feedback in response to classification results. Instructors can use such a system to automatically supervise posture and motion of students, i.e., to detect common mistakes that are difficult to recognize when observing students from far away, and to provide immediate audible or tactile feedback for corrections during courses. The presented approach can further be applied to supervise posture and to alert users to potentially harmful body movements performed during daily physical activities. <s> BIB003 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> We present a novel concept for an audience voting system for judged sports events. It is based on wireless wearable motion sensors utilizing the natural behaviour of sports spectators -clapping and cheering. This paper describes initial results from a user study that guided our design process. We further present two preliminary prototypes focusing on hardware and design feasibility respectively. Results confirm our assumption that the system does not provide objective results, but has the potential to increase the spectator experience by giving audience members the feeling of being part of the voting process. <s> BIB004 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> Advances in electronics have brought the promise of wearable computers to near reality. Such systems can offer a highly personal and mobile information and communication infrastructure. Previous research has investigated where wearable computers can be located on the human body - critical for successful development and acceptance. However, for a location to be truly useful, it needs to not only be accessible for interaction, socially acceptable, comfortable and sufficiently stable for electronics, but also effective at conveying information. In this paper, we describe the results from a study that evaluated reaction time performance to visual stimuli at seven different body locations. Results indicate that there are numerous and statistically significant differences in the reaction time performance characteristics of these locations. We believe our findings can be used to inform the design and placement of future wearable computing applications and systems. <s> BIB005 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> In this paper we introduce the concept of a wearable assistant for swimmer, called SwimMaster. The SwimMaster consists of acceleration sensors with micro-controllers and feedback interface modules that swimmer wear while swimming. With four different evaluation studies and a total of 22 subjects we demonstrate the functionality and power of the SwimMaster system. We show how a wide range of swim parameters can be monitored and used for a continuous swim performance evaluation. These parameters include the time per lane, the swimming velocity and the number of strokes per lane. Also swim style specific factors like the body balance and the body rotation are extracted. Finally three feedback modalities are tested and evaluated. With these means we show the ability of the SwimMaster to assist a swimmer in achieving the desired exercise goals by constantly monitoring his/her swim performance and providing the necessary feedback to achieve the desired workout goals. <s> BIB006 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> In many sports, athletes are spatially separated from their coach while practicing an exercise. This spatial separation makes learning new skills arduous because the coach cannot give instructions or feedback on performance. We present the findings of an in the wild study that demonstrate the potential for teaching sport skills with realtime tactile instructions. We focused on snowboard training. Ten amateurs learned a riding technique with a wearable system that automatically provided tactile instructions during descents. These instructions were in sync with the movements of the snowboard and signaled how to move the body. We found that tactile instructions could help snowboarders to improve their skills. We report insights into the snowboarders' opinion and give recommendations for teaching sport skills with tactile instructions. Our findings help to identify the conditions under which tactile instructions can support athletes in sports training. <s> BIB007 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> We present Cyclo, our prototype of a personal assistant for bike training using Google Glass. We describe our requirement study with 35 users and our design process for developing a novel application for Glass. Our hands-free user interface is potentially more convenient to use than traditional speedometers, and it provides instant performance feedback and context-aware notifications overlaid on the biker's view. <s> BIB008 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> Abstract Running is one of the most popular sports for the masses. However, not every runner might run properly. Incorrect running technique decreases movement efficiency and increases the risk of injury. In this work, we present the development of a smartphone application to provide feedback on running technique on the example of arm carriage. Recognition algorithms were developed in a preliminary study with 10 participants. Investigating sensor positions and modalities, we found that a single IMU on the upper arm yielded an accuracy of 80.73% for the assessment of arm movement. We implemented our approach as a smartphone application and found that runners improved their arm movement using our application within a user study including 23 participants. Results from questionnaires revealed high user acceptance (average rating of 8 from 10 possible points). <s> BIB009 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> We developed a wearable device to improve lower limb sport training. The ::: presented system consists of a pair of spandex shorts which embed a processor ::: unit, 2 accelerometers and 2 vibro motors. The accelerometers are located in ::: proximity to the knees and measure tri-axial accelerations. We present a ::: novel method to compute and correct asymmetry of lower limbs during training. ::: The user performs an initial calibration phase which sets the accelerometer ::: reference frames. While running, the system continuously refines the ::: calibration using principal component analysis to take in account occasional ::: shorts assessments. The system activates a corrective vibro feedback on the ::: specific leg according to an asymmetry metric based on: (i) foot ground ::: impact, (ii) phase error between legs, (iii) transversal knee movements. User ::: tests demonstrated that the device is ergonomic to wear, easy to use and the ::: corrective vibro feedback is appreciated during the training. <s> BIB010 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> In recent years the sport of climbing has seen consistent increase in popularity. Climbing requires a complex skill set for successful and safe exercising. While elite climbers receive intensive expert coaching to refine this skill set, this progression approach is not viable for the amateur population. We have developed ClimbAX - a climbing performance analysis system that aims for replicating expert assessments and thus represents a first step towards an automatic coaching system for climbing enthusiasts. Through an accelerometer based wearable sensing platform, climber's movements are captured. An automatic analysis procedure detects climbing sessions and moves, which form the basis for subsequent performance assessment. The assessment parameters are derived from sports science literature and include: power, control, stability, speed. ClimbAX was evaluated in a large case study with 53 climbers under competition settings. We report a strong correlation between predicted scores and official competition results, which demonstrate the effectiveness of our automatic skill assessment system. <s> BIB011 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> The “wearability” of wearable technology addresses the factors that affect the degree of comfort the wearer experiences while wearing a device, including physical, psychological, and social aspects. While the physical and psychological aspects of wearing technology have been investigated since early in the development of the field of wearable computing, the social aspects of wearability have been less fully-explored. As wearable technology becomes increasingly common on the commercial market, social wearability is becoming an ever-more-important variable contributing to the success or failure of new products. Here we present an analysis of social aspects of wearability within the context of the greater understanding of wearability in wearable technology, and focus on selected theoretical frameworks for understanding how wearable products are perceived and evaluated in a social context. Qualitative results from a study of social acceptability of on-body interactions are presented as a case study of social wearability. <s> BIB012 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> Group exercise has multiple benefits including greater adherence to fitness regimens, increased enjoyment among participants, and enhanced workout intensity. While a large number of technology tools have emerged to support real-time feedback of individual performance, tools to support group fitness are limited. In this paper, we present a set of wearable e-textile displays for running groups called Social Fabric Fitness (SFF). SFF provides a glanceable, shared screen on the back of the wearer's shirt to increase awareness and motivation of group fitness performance. We discuss parallel prototyping of three designs-one flexible e-ink and two flexible LED-based displays; the selection and refinement of one design; and two evaluations'a field study of 10 running groups and two case studies of running races. Our qualitative findings indicate that SFF improves awareness of individual and group performance, helps groups stay together, and improves in-situ motivation. We close with reflections for future athletic e-textile displays. <s> BIB013 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> Marathon is very popular in recent years. However, finishing the game is no easy task, especially for beginners. Regular practices and training are needed. With the availability of wearable devices, it is possible to develop virtual coaches that monitor the progresses of individual runners closeup and guide them through tailor-made training schedules. Unfortunately, most existing wearable devices only record physiological signals of the runners and rely on off-line processing to provide feedbacks. In this paper, we present the design and development of an on-line virtual coach, which performs real-time tracking and analysis of the physiological status of the runner and suggests appropriate adjustments on the exercise intensity. The proposed virtual coach is a pure software solution and can work with any wearable device that monitors the heart rate and running speed of the runner. The main challenge of our system is to predict when the runner will reach the various running states and instruct the runner to adjust the speed just ahead of time so that her/his body can react in time to maintain the required training intensity. Experiments on real users show that our proposed algorithms can correctly predict the running states of the runners and help them to better maintain the required intensity to maximize the training effects. <s> BIB014 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> Modern roller derby is a predominately female driven full contact sport. A relatively new and evolving sport, players are yet to benefit from recent advances in wearable technologies. This paper reports on our initial investigations into player attitudes towards the use of technology as a training aid. Our survey results highlight broad support for the development of a wearable training device. Over 300 participants identified the skills they want help with improving and provided some initial feedback on the appropriateness of feedback modalities and location of a wearable training device. We end the paper by introducing our first interaction prototype, TapTrain, that allows skaters to access feedback on their technique while skating. <s> BIB015 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> Wearable fitness devices have demonstrated the capacity to improve overall physical activity, which can lead to physical and mental health improvements as well as quality of life gains. Although wheelchair athletes who participate in adaptive sports are interested in using wearable fitness trackers to capture their activity, we have observed low adoption of wearable fitness trackers among wheelchair athletes. We interviewed five wheelchair athletes and three physical and occupational therapists to explore fitness activities, experience with wearable technology, and potential uses for wearable fitness devices. None of the wheelchair athletes we interviewed had previously used any wearable fitness devices, however four out of five were interested in tracking their physical activity. We present five thematic areas helpful for thinking about wearable computing systems and accessibility challenges that arise based on incorrect assumptions about the athletic community. We highlight opportunities for improving the impact and accessibility of fitness tracking technologies for wheelchair athletes. These opportunities include improving the analysis of data from existing sensors, instrumenting the custom equipment used by adaptive sport athletes, and revising the language used in the presentation of fitness data to create a more inclusive community of users. <s> BIB016 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> In this paper, we present a field study on the learning of climbing aimed at defining the design space of wearable devices to support beginners. Three main findings have emerged from our study. First, climbing has a strong emotional impact on beginners; therefore, learning to climb requires mastering new motor patterns as well as negative emotions, such as stress and fear. Second, the feeling of danger that climbers often experience can be mitigated by trust in the climbing partner and the perception of her active presence. Finally, a big problem in climbing is the communication difficulty between the climbing partners and between climber and instructor. We conclude the paper presenting four design considerations for the design of wearable devices meant to support the learning of climbing by providing the actors involved with augmented communication. Such augmented communication should address both the physical and the emotional difficulties of this sport. <s> BIB017 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> Recent advances in technology fostered the commercialization and usage of wearable devices. Among diverse form factors, wrist worn devices stand out. Benefitting from a conventional format and easy access, wrist worn devices, such as smart watches and fitness trackers, have been gaining popularity. While their continuous usage and close contact with the human body enable various applications, their limited computational resources summed with continuous changes in the context of use challenge designers in providing effective interactive solutions for end users. Seeking to understand how the context of use impacts the user experience and interaction with ten popular wrist worn wearables, in this study we analyzed the users' feedback: 545 users' comments were collected from Amazon, coded and aggregated. Based on the users' feedback, we identify 31 major problems that are currently faced in wrist worn interfaces. The analyses of the users' feedback led to a discussion about the causes and severity of those problems, and also to the definition of a set of design implications aimed at improving the user interaction with the next-generation wrist worn wearables. <s> BIB018 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> Collecting a digital footprint of data from one's everyday activities is becoming an information source for preventive health care. Wearable sensor technologies combined with mobile phone applications offer an interesting way to collect and monitor personal activity data for personal use, in addition to providing information for wellness and health care professionals. In this paper we present our service design approach for designing a mobile MyData Wellness concept that was developed for young athletes. The concept aims to combine different possibilities of mobile technologies to create a tool that can provide versatile support for wellness. The salient findings from the concept evaluation show that active young people find tracking sports data motivating and interesting, and call for a unified service that combines different wellness-related aspects of life. <s> BIB019 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> Wearable sports devices like GPS watches and heart rate monitors are ubiquitous in sports like running or road cycling and enable the users to receive real-time performance feedback. Although rock climbing is a trending sport, there are little to no consumer electronics available to support rock climbing training during exercise. In this paper, we investigated the acceptance and appropriateness of wearables in climbing on different body parts. Based on an online survey with 54 climbers, we designed a wearable device and conducted a perception study with 12 participants in a climbing gym. Using vibro-tactile, audible, and visual cues while climbing an easy route and a hard route, requiring high physical and cognitive load, we found that the most suited notification channel is sound, directly followed by vibro-tactile output. Light has been found to be inappropriate for the use in the sport of climbing. <s> BIB020 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> 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. <s> BIB021 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> The interest in virtual and augmented reality exploded during the last two years. We propose the use of these systems in the field of sports by combining this technology with a local area radio-based localization technology. This allows for novel application scenarios using virtual environments in team-based sports, which are outlined in this work. We conducted an online survey among 227 athletes about the acceptance of virtual reality headsets for training in different kind of sport disciplines. <s> BIB022 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> We proposed a new haptic instruction system for sports trainings that provides field players with instructed directions. The system consists of a stimulation unit (SU) for a player and an instruction unit (IU) for an instructor. Players wear the SU around their waist, and can recognize instructed directions by vibrations using 13 vibration actuators. The IU sends a direction where the joystick tilts to the SU via wireless communication modules. Preliminary experiments confirmed that the all participants did not feel the slipping away of the SU, and all participants were able to recognize its vibration even though they were running at 5, 10 km/h and standing (0 km/h). However, at 15 km/h, a participant who has a plump body recognized that a little or hardly recognized that at back part. We need to improve the method of providing stimuli at back part. By using the system, instructors and directors can provide the instructed directions to a field player without both any voice and gesture. <s> BIB023 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> Research into the kinematic training of elite divers shows a demand for diver training using biomechanical feedback. With suitable inertial data and tactile feedback, divers and their coaches could better understand their dives and failure modes. This would help improve technique and reduce fatigue during both training and competition, resulting in higher quality dives. We developed the Diving Coach Monitor (DCM) that can wire-lessly stream inertial data to an assistant as well as vibrotactially signal an athlete during a dive. The DCM is comprised of a wearable sensor module, worn by a diver and a smartphone application for the diver's coach. The diver's coach uses the smartphone application to signal the wearable sensor module, throughout the training session. The wearable sensor module receives the control commands and acts accordingly with one of the following actions: vibrate (to signal the diver); commence inertial data sampling; stop inertial data sampling and transmit data back to the smartphone application. While the DCM is water-proof, we trialled the DCM in a “dry-land” environment, as divers often train with trampoline spotting rigs and (occasionally) a safety harness. We also conducted multiple trial sessions with circus and gymnastic aerial apparatus and athletes. Our tests showed accurate measurement and low latency compared to video motion analysis. <s> BIB024 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> The ClimbingAssist supports beginners in improving their technique. It uses a pressure sensitive foil on an insole and gives direct feedback while climbing depending on the pressure on the foot and the movement speed. We evaluated our design in a study in a climbing gym. <s> BIB025 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> Cycling is a popular sport in which assistance devices are used for measuring heart rate, speed or cadence. Even if much more important than performance metrics, systems for supporting communication within the group are not available. Speech and standard hand-gestures are commonly used by cyclists to communicate danger and to propagate commands from the front to the end of the group. We propose an approach to enhance the communication chain by using gesture recognition and LEDs sewed into the backside of the cyclists' shirts. We studied the requirements for using the system for augmenting gestures with light, by presenting our prototype to a group of cyclists asking for their opinion. We found that about half of the cyclists fear new irritations, but most of the cyclists would also appreciate the support, especially for supporting large groups. <s> BIB026 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> The use of external motion sensors with the athletes' wearables will enable new advanced applications for providing feedback on movement. We show how visual 3D-feedback based on Inertial Measurement Units (IMU) is technically and conceptually feasible. Our wearable-app connects to our custom designed IMU-pods for measuring the legs' orientation. The App then shows an animated kinematic model in 3D. Our study with ten runners further contributes by providing first insights into how to apply natural, live-feedback with wearables for supporting run-training. Our prototype for the smartphone and head-up display demonstrates great potential for personal- and everyday use. <s> BIB027 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> We present JackIn Airsoft, a system for generating maps for multi-player sport activities and sharing their first-person views (FPVs). In first-person shooting (FPS) games, maps are generated for the visualization of the player's location; these maps are used for strategic play and discussions. FPS games are a virtual experience of shooting or of military activities; the displaying of maps on a screen is a technique designed for game playing. We address the challenge of adapting this effective map visualization technique to real-world strategic sports. In this paper, we introduce our prototype map generator for airsoft sports that is based on the usage of wearable cameras and simultaneous localization and mapping (SLAM). The system enables users to switch between the FPV and the generated map in order to share a player's experience and a strategic overview for team sports. We applied ORB-SLAM2 to multiple recorded FPV videos to discuss the situations and conditions appropriate for our system. <s> BIB028 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> Tai-Chi Chuan (TCC) is a famous physical exercise and well-known for being able to effectively promote physical well-being. Many people have been interested in learning TCC at the beginning, but eventually failed in mastering it due to the lack of a constantly accompanying master on the side. In this paper, we present an augmented-learning tool, called "My Tai-Chi Coaches", for learning TCC. By wearing an optical see-through Head-Mounted Display (HMD), the users can have their own private coaches-on-demand that will guide them in practicing TCC. To solve the "attention-sticking" problem, we propose the use of "redundant coaches" and high-lighting the primary coach at every instant. When the user wants to adjust his posture to mimic the coach's movement, he can simply suspend his motion, and then the drone will fly to a proper position to capture the images of the user's posture, and display them on an augmented mirror placed near by the highlighted or gazed coach. In addition to learning TCC, the proposed augmented-learning tool can also be used for learning dancing, yoga, sporting, and for rehabilitation. <s> BIB029 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> Most interactive sports-oriented products that are commercially available focus on individual athletes. The ones that focus on team sports rarely go beyond performance monitoring. Therefore, in this case study we focus on team dynamics in secondary school sports teams. These teams typically have to deal with unbalanced engagement due to skill level differences. This can impede the goals of these PE-classes; to raise young people's enthusiasm for a variety of sports and to teach them how to work together as a team. In this project we explore a design solution aimed at balancing engagement in these mixed level sports teams, through an intelligent system of connected light jerseys. The jerseys, iteratively developed through experiential prototypes that were used during secondary school basketball games, were able to measure ball possession and give feedback through a series of light stripes. In this paper we describe two iterations of this case study and our quantitative and qualitative findings of team engagement. <s> BIB030 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> Many people who are blind or partially blind continue to enjoy alpine sports such as skiing and snowboarding. Because of their restricted visual perception, visually impaired (VI) skiers are usually accompanied by a ski guide. We present VIHapp, a system consisting of smart ski poles, smart armbands and an instrumented ski to enable communication between VI skiers and ski guides. Guides send commands to VI skiers by pressing a button on their ski poles. VI skiers receive commands in the form of vibrations on their armbands. The smart ski detects turns performed by VI skiers and sends notifications to the guide's smart ski poles. <s> BIB031 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> Abstract There has been a market surge in both provision of and demand for fitness applications and sport wearables. These wearables often come equipped with highly sophisticated biometric data (e.g. heart rate) functionalities that make the capture and sharing of such biometric data increasingly common practice. A few research studies have considered the effect that sharing biometric data has on those individuals sharing this data. However, little is known regarding the social impact of sharing this data in real-time and online. In this study, we investigate whether there is value in sharing heart rate data within social applications and whether sharing this data influences the behavior of those seeing this data. We do so by conducting a study where the heart rate data of runners competing in a 5-km road race is shared in real-time with 140 online spectators. We collect rich quantitative data of user interaction though server logs, and a qualitative data set through interviews and online users' comments. We then compare and contrast the behavior of online spectators who are presented with heart rate data together with contextual data, and those who are only presented with contextual data, for example, location. We also examine whether this difference is dependent on the social relation between the athletes and the spectators. Results indicate that spectators who are presented with the runners' heart rate data support the athletes more and rate the presented system more positively. These effects are dependent on the social tie between the athletes and spectators. This is one of the first studies to carry out an empirical investigation in the wild on the effects of sharing heart rate data in an online social context. In this light, in addition to supporting earlier literature, the outcomes present new insights and research directions within the sporting context. <s> BIB032 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> We introduce Goby, a swimming aid that provides audio feedback for blind and visually impaired athletes. Goby's activity tracker is worn on the thigh and uses a downward-facing camera to track the swimmer's position in the pool. Goby detects when the user is swimming outside the lane or approaching a wall, and warns the user via an audio notification. In this paper, we introduce the Goby prototype and share formative feedback about the prototype from blind and sighted swimmers. <s> BIB033 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> In running, knee-related injuries are very common. The main cause are high impact forces when striking the ground with the heel first. Mid- or forefoot running is generally known to reduce impact loads and to be a more efficient running style. In this paper, we introduce a wearable running assistant, consisting of an electrical muscle stimulation (EMS) device and an insole with force sensing resistors. It detects heel striking and actuates the calf muscles during the flight phase to control the foot angle before landing. We conducted a user study, in which we compared the classical coaching approach using slow motion video analysis as a terminal feedback to our proposed real-time EMS feedback. The results show that EMS actuation significantly outperforms traditional coaching, i.e., a decreased average heel striking rate, when using the system. As an implication, EMS feedback can generally be beneficial for the motor learning of complex, repetitive movements. <s> BIB034 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <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> BIB035 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> Mobile technologies have become an important part of run training, however, existing technologies focus on performance metrics (e.g., distance and pace), which makes it difficult for runners to improve their running technique. In this paper, we present Strive, a wearable running technology that aims to assist runners in achieving rhythmic breathing; a running technique that potentially leads to improved results and lower injury risk. Strive continuously collects physiological data and uses haptic feedback to provide real-time assistance during runs. As communicating technique-related information in the dynamic and complex context of a run is challenging, we present two studies. The first study investigates how runners adapt to two different vibration patterns; and the second study explores the temporality of the assistance through three different approaches: Continuous, periodical, and self-serviced. Based on these studies, we discuss and provide insights on interacting with technologies during runs. <s> BIB036 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> The growing popularity of winter sports, as well as the trend towards high speed carving skis, have increased the risk of accidents on today's ski slopes. While many skiers now wear ski helmets, their bulk might in turn lower skiers' ability to sense their surroundings, potentially leading to dangerous situations. In this paper, we describe our "Smart" Ski Helmet (S-SH) prototype. S-SH uses a set of laser range finders mounted on the back to detect skiers approaching from behind and warns the wearer about potential collisions using three LEDs mounted at the helmet's front edge, slightly above the wearer's eye level. In this work, we describe a controlled experiment with 20 ski and snowboarding enthusiasts and a follow-up on-slope deployment with 6 additional participants of varying levels of expertise. Our findings indicate that the S-SH can significantly increase skiers' peripheral perception on traverse trails. <s> BIB037 </s> Designing Wearable Systems for Sports: A Review of Trends and Opportunities in Human–Computer Interaction <s> D. Wearability <s> While wearable devices for fitness have gained broad popularity, most are focused on tracking general activity types rather than correcting exercise forms, which is extremely important for weightlifters. We interviewed 7 frequent gym-goers about their opinions and expectations for feedback from wearable devices for weightlifting. We describe their desired feedback, and how their expectations and concerns could be balanced in future wearable fitness technologies. <s> BIB038
The term wearability refers to the ability of an artifact to be worn on the human body BIB001 . It is worth noticing that a good wearability is not only a matter of physical comfort, but also of social and psychological comfort BIB012 , in order to be effective in conveying information and accessible for interaction BIB005 . Few articles (8 out of 57) in our corpus directly address the topic of wearability BIB006 , BIB017 , BIB018 , BIB019 - BIB020 , BIB016 . These are exploratory papers presenting investigations that may inform the design of new wearable devices. Even though the term "wearability" is not explicitly mentioned, these authors attempt to find the best body location to place the device in order to ensure comfort, accuracy of sensing, and perceptibility of feedback. Bäch-lin et al. BIB006 and Kosmalla et al. BIB020 , for instance, attempt to discover the best form factors, body locations, or feedback modalities in swimming and climbing, respectively. The majority of the selected papers (29 out of 57) present new wearable prototypes or adapt multipurpose commercial wearables to the sports domain (e.g., goggles) without discussing their wearability. Yet, by analyzing the proposed devices, they offer implicit motivations for their design choices. The most common form and location are a band or a watch to be placed on the wrist (21 papers). This is convenient because it exploits the conventional location of watches and bracelets, which are already culturally recognized and accepted. Furthermore, placing the device on the wrist allows feedback to be visualized easily, and facilitates the collection of both physical and physiological data, e.g., heart signal and body movements. Other body locations explored in the corpus are the head BIB021 , BIB028 , BIB008 , BIB029 ,  , BIB022 , the neck  , the thorax BIB013 , BIB023 , BIB024 , BIB014 , BIB030 , the arms BIB031 , BIB009 , BIB032 , the legs BIB010 , BIB033 , the feet BIB025 , BIB034 , and multiple locations all over the body BIB035 . This last group includes wearable systems composed of different devices for sensing and sending feedback BIB026 , BIB027 , BIB036 , BIB015 , BIB032 , as well as wearable systems for full-body sports BIB002 , BIB007 , BIB003 , BIB038 . See Fig. 2 for an overview of the body locations addressed in the corpus. By analyzing the papers that have moved beyond the "watch metaphor," it emerges that the decisions on the shape to be given to the artifact, as well as on the position of the body where to place it, are made on the basis of two reasons: 1) the role of the device (e.g., augmenting the experience, improving the communication with teammates, etc.); 2) the possibility of embedding the device in an artifact already used during the sports practice (e.g., clothes or gear), or the need to create a new "object." It is also apparent that the studies aiming to augment the sports experience typically rely on HMDs, using AR or VR. HMDs have been studied both in sports where goggles are already part of the athlete's equipment, such as skiing and snowboarding BIB021 , BIB028 ,  , BIB037 , and in sports where the enhancement of the experience would require an additional artifact BIB008 , BIB029 , BIB022 . By contrast, research aimed at supporting the athlete's performance during training or learning defines the wearable's shape and location on the basis of the body parts involved in the sport (for ensuring a more precise movement detection), as well as the target of the feedback (for a better feedback perceptibility). To ensure optimal sensing, they can be placed on the athlete's feet BIB003 , BIB025 , BIB009 , legs BIB027 , BIB010 , chest BIB014 , or wrist BIB011 , depending on the types of movements required by each sport. To ensure the perceptibility of the feedback, wearables are typically positioned on the athlete's arms BIB009 , BIB032 , ears BIB033 , or waist BIB024 . When the feedback targets other athletes involved in the sports activity (i.e., teammates or opponents), it is commonly embedded in the athlete's apparel and displayed on the thorax to be more visible BIB013 , BIB026 , BIB030 ; instead, when it is addressed to external actors, such as judges and audience, the information is captured by sensors placed on the athlete and is displayed on screens BIB004 , BIB002 ,  .