This paper identifies key properties of expertise in sport predicated on the performer-environment relationship. Weaknesses of traditional approaches to expert performance, which uniquely focus on the performer and the environment separately, are highlighted by an ecological dynamics perspective. Key properties of expert movement systems include 'multi- and meta-stability', 'adaptive variability', 'redundancy', 'degeneracy' and the 'attunement to affordances'. Empirical research on these expert system properties indicates that skill acquisition does not emerge from the internal representation of declarative and procedural knowledge, or the imitation of expert behaviours to linearly reduce a perceived 'gap' separating movements of beginners and a putative expert model. Rather, expert performance corresponds with the ongoing co-adaptation of an individual's behaviours to dynamically changing, interacting constraints, individually perceived and encountered. The functional role of adaptive movement variability is essential to expert performance in many different sports (involving individuals and teams; ball games and outdoor activities; land and aquatic environments). These key properties signify that, in sport performance, although basic movement patterns need to be acquired by developing athletes, there exists no ideal movement template towards which all learners should aspire, since relatively unique functional movement solutions emerge from the interaction of key constraints.

3Expert decision-making can be directly assessed, if sport action is understood as 4 an expression of embedded and embodied cognition. Here, we discuss evidence for this 5 claim, starting with a critical review of research literature on the perceptual-cognitive 6 basis for expertise. In reviewing how performance and underlying processes are 7 conceived and captured in extant sport psychology, we evaluate arguments in favour of 8 a key role for actions in decision-making, situated in a performance environment. Key 9 assumptions of an ecological dynamics perspective are also presented, highlighting how 10 behaviours emerge from the continuous interactions in the performer-environment 11 system. Perception is of affordances; and action, as an expression of cognition, is the 12 realization of an affordance and emerges under constraints. We also discuss the role of 13 knowledge and consciousness in decision-making behaviour. Finally, we elaborate on 14 the specificities of investigating and understanding decision-making in sport from this 15 perspective. Specifically, decision-making concerns the choice of action modes when 16 perceiving an affordance during a course of action, as well as the selection of a 17 particular affordance, amongst many that exist in a landscape in a sport performance 18 environment. We conclude by pointing to some applications for the practice of sport 19 psychology and coaching and identifying avenues for future research. How expert athletes decide to do what they do is a topic that has interested 27 scientists for several decades (e.g., Beise & Peasley, 1937), and particularly sport 28 psychologists(e.g., Straub & Williams, 1984). It has been argued that sport is a most 29 appropriate context for studying expert decision-making (Gilovitch, 1984, Gilovitch et al, 30 1985. According to Gobet (2016), sport is a domain of expertise, where expertise relies 31 on perception: "experts literally 'see' things differently compared to novices" and "these 32 differences in perception and knowledge affect problem solving and decision making" 33 (Gobet, 2016, p.7). 34 Predicated on these ideas, studies of decision-making in sport have intensively 35 tested athletes'perception and anticipation, attention, memory, and decision-making. 36An important gap emerges immediately: decision-making in sport, by following trends 37 in cognitive psychology, has neglected the important role of action and its constitutive 38 role in cognition (Araújo, Ripoll & Raab, 2009;Prinz, Beisert & Herwig, 2013; Wolpert & 39 Landy, 2012). In this article, we critically overview research on the perceptual-cognitive 40 basis of decision-making, before we present an action-based alternative, from the 41 ecological dynamics framework, clarifying repercussions for theory and research in 42 sport psychology. 43 44The perceptual-cognitive framework for the study of decision-making in sport 45Currently, the perceptual-cognitive view of decision-making tends to focus on 46 use of perception, memory and decision-making tas...

The research base for rock climbing has expanded substantially in the past 3 decades as worldwide interest in the sport has grown. An important trigger for the increasing research attention has been the transition of the sport to a competitive as well as recreational activity and the potential inclusion of sport climbing in the Olympic schedule. The International Rock Climbing Research Association (IRCRA) was formed in 2011 to bring together climbers, coaches and researchers to share knowledge and promote collaboration. This position statement was developed during and after the 2 nd IRCRA Congress which was held in Pontresina, in September 2014. The aim of the position statement is to bring greater uniformity to the descriptive and statistical methods used in reporting rock climbing research findings. To date there is a wide variation in the information provided by researchers regarding the climbers' characteristics and also in the approaches employed to convert from climbing grading scales to a numeric scale suitable for statistical analysis. Our paper presents details of recommended standards of reporting that should be used for reporting climber characteristics and provides a universal scale for the conversion of climbing grades to a number system for statistical analysis.

We examined the preferred mode of arm coordination in 14 elite male front-crawl swimmers. Each swimmer performed eight successive swim trials in which target velocity increased from the swimmer's usual 3000-m velocity to his maximal velocity. Actual swim velocity, stroke rate, stroke length and the different arm stroke phases were then calculated from video analysis. Arm coordination was quantified by an index of coordination based on the lag time between the propulsive phases of each arm. The index expressed the three coordination modes in the front crawl: opposition, catch-up and superposition. First, in line with the dynamic approach to movement coordination, the index of coordination could be considered as an order parameter that qualitatively captured arm coordination. Second, two coordination modes were observed: a catch-up pattern (index of coordination= -8.43%) consisting of a lag time between the propulsive phases of each arm, and a relative opposition pattern (index of coordination= 0.89%) in which the propulsive phase of one arm ended when the propulsive phase of the other arm began. An abrupt change in the coordination pattern occurred at the critical velocity of 1.8 m. s(-1), which corresponded to the 100-m pace: the swimmers switched from catch-up to relative opposition. This change in coordination resulted in a reorganization of the arm phases: the duration of the entry and catch phase decreased, while the duration of the pull and push phases increased in relation to the whole stroke. Third, these changes were coupled to increased stroke rate and decreased stroke length, indicating that stroke rate, stroke length, the stroke rate/stroke length ratio, as well as velocity, could be considered as control parameters. The control parameters can be manipulated to facilitate the emergence of specific coordination modes, which is highly relevant to training and learning. By adjusting the control and order parameters within the context of a specific race distance, both coach and swimmer will be able to detect the best adapted pattern for a given race pace and follow how arm coordination changes over the course of training.

This study investigated the functional intra-individual movement variability of ice climbers differing in skill level to understand how icefall properties were used by participants as affordances to adapt inter-limb coordination patterns during performance. Seven expert climbers and seven beginners were observed as they climbed a 30 m icefall. Movement and positioning of the left and right hand ice tools, crampons and the climber’s pelvis over the first 20 m of the climb were recorded and digitized using video footage from a camera (25 Hz) located perpendicular to the plane of the icefall. Inter-limb coordination, frequency and types of action and vertical axis pelvis displacement exhibited by each climber were analysed for the first five minutes of ascent. Participant perception of climbing affordances was assessed through: (i) calculating the ratio between exploratory movements and performed actions, and (ii), identifying, by self-confrontation interviews, the perceptual variables of environmental properties, which were significant to climbers for their actions. Data revealed that experts used a wider range of upper and lower limb coordination patterns, resulting in the emergence of different types of action and fewer exploratory movements, suggesting that effective holes in the icefall provided affordances to regulate performance. In contrast, beginners displayed lower levels of functional intra-individual variability of motor organization, due to repetitive swinging of ice tools and kicking of crampons to achieve and maintain a deep anchorage, suggesting lack of perceptual attunement and calibration to environmental properties to support climbing performance.