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Entropy, degrees of freedom, and free climbing: A thermodynamic study of a complex behavior based on trajectory analysis

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Abstract

Used calculations of the entropies (ENTs) of the route-finding trajectories (TRJs) of rock climbers to examine the kinetics of the skill optimization process. The shape of the ENT curve was assumed to represent an index of TRJ complexity. Three average climbers (ACs) and 4 skilled climbers (SCs) completed 10 successive repetitions of a moderately difficult climb. Mean ENTs of SCs were lower than those of ACs, with ENTs decreasing over successive climbs in both groups. Climb number and skill level interacted such that ENTs initially fell rapidly for the SCs but leveled off after the 3rd climb, while ENTs for the ACs dropped gradually until the 8th climb. The use of the ENT index is justified on the basis of the strong relationship existing among ENT, information processes, and the system's degrees of freedom as viewed from movement emergence and movement construction perspectives. (French, Spanish, German & Italian abstracts) (PsycINFO Database Record (c) 2012 APA, all rights reserved)

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... Along with this quick development, questions have rised about safety and equipment, but also about biomechanics, movement strategies, and learning capacity. In reviewing the scientific literature, we found only a few authors dealing with the analysis of rock climbing movements: Cordier and colleagues (Cordier, France, Bolon, & Pailhous, 1993; Cordier, France, Pailhous, & Bolon, 1994) analyzed the learning strategy of a complex motor task using entropy as a global variable; Bourdin, Teasdale, and Nougier (1996) worked on the organization of reaching and grasping movements due to the strong postural constraints induced by rock climbing; Quaine dealt with equilibrium tasks (Quaine, 1997Quaine, , 1999) and force distribution on the holds (Quaine, Martin, & Blanchi, 1997), but only for a single movement; a few authors (for example, Klauser et al., 2002; Peters, 2001; Rohrbough, Mudge, & Schilling, 2000) focused their studies on the most frequent injuries in climbers; Boschker and Bakker (2002) recorded climbers with a video camera to analyze observational learning strategies; Noè (2006) analyzed the effects of supporting wall inclination on the anticipatory postural adjustments in rock climbing tasks. All studies cited, except Boschker and Bakker's, were performed on elite climbers. ...
... From the body CM coordinates (X, Y, Z), four different parameters were computed: the geometric entropy (H), the absolute velocity (jVj), the absolute acceleration (jAj) and the power of acceleration time course (P); each parameter is described in detail in the following. The geometric entropy (H) was computed by taking the natural logarithm of two times the length of the pattern travelled by the body center of mass (LP) divided by the perimeter of the convex hull around that path (c) (Cordier et al., 1993, 1994, see also Boschker & Bakker, 2002). H was computed on the frontal plane (XY), on the transverse plane (XZ) and on the sagittal plane (YZ) as ...
... In general, the entropy of a system is a measure of the amount of order vs. chaos of that system. As explained in Cordier et al. (1993 Cordier et al. ( , 1994) and Boschker and Bakker (2002), the geometric entropy reveals the amount of fluency/curvature of a curve: the higher the entropy, the higher the disorder of the system. In our case the geometric entropy H is associated with the oscillations of the climber's center of mass, represented by the length of its path. ...
Article
The purpose of the present study was to search for common patterns and for differences in climbing strategies in a group of recreational climbers. Twelve participants were involved in the study. Each participant climbed a simple indoor route consisting of a 3m horizontal shift followed by a 3m ascent for five times. Climbers could choose their own style, their preferred speed and holds. Their motion was recorded through motion capture based on passive markers. Results suggested that two main climbing strategies were used: the first preferring agility over force and the second preferring force over agility. We also found that our best climbers tried to minimize power during all trials.
... Therefore, the designated climbing task corresponded to a sub-maximal grade of difficulty for the participants, which prevented any possible fatigue effects during each testing session. They had the following task-goal: to find the way to climb up the surface as fluently possible, i.e., without falling down and by minimizing pauses and rest periods of body displacement during the ascent (Cordier et al., 1993(Cordier et al., , 1994Seifert et al., 2014b). Instructions were not made too specific to allow coordination patterns to emerge as each climber exhibited exploratory behaviors under the varying task constraints. ...
... Frontiers in Psychology | www.frontiersin.org to climb with highest fluency, the climbing fluency of the hip trajectory was assessed by the geometric index of entropy (GIE) (Cordier et al., 1993(Cordier et al., , 1994Sibella et al., 2007). GIE was calculated by recording the distance path covered by the hip (L) and the perimeter of the convex hull around that path (c) according to the following equation (Cordier et al., 1993(Cordier et al., , 1994: GIE = logn2L/c. ...
... to climb with highest fluency, the climbing fluency of the hip trajectory was assessed by the geometric index of entropy (GIE) (Cordier et al., 1993(Cordier et al., , 1994Sibella et al., 2007). GIE was calculated by recording the distance path covered by the hip (L) and the perimeter of the convex hull around that path (c) according to the following equation (Cordier et al., 1993(Cordier et al., , 1994: GIE = logn2L/c. According to Cordier et al. (1993Cordier et al. ( , 1994, the geometric index of entropy measures reveal the amount of fluency/curvature of a curve. ...
Article
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This study investigated how environmental design shapes perceptual-motor exploration, when meta-stable regions of performance are created. Here, we examined how creating meta-stable regions of performance could destabilize pre-existing skills, favoring greater exploration of performance environments, exemplified in this study by climbing surfaces. In this investigation we manipulated hold orientations on an indoor climbing wall to examine how nine climbers explored, learned, and transferred various trunk-rolling motion patterns and hand grasping movements. The learning protocol consisted of four sessions, in which climbers randomly ascended three different routes, as fluently as possible. All three routes were 10.3 m in height and composed of 20 hand-holds at the same locations on an artificial climbing wall; only hold orientations were altered: (i) a horizontal-edge route was designed to afford horizontal hold grasping, (ii) a vertical-edge route afforded vertical hold grasping, and (iii), a double-edge route was designed to afford both horizontal and vertical hold grasping. As a meta-stable condition of performance invite an individual to both exploit his pre-existing behavioral repertoire (i.e., horizontal hold grasping pattern and trunk face to the wall) and explore new behaviors (i.e., vertical hold grasping and trunk side to the wall), it was hypothesized that the double-edge route characterized a meta-stable region of performance. Data were collected from inertial measurement units located on the neck and hip of each climber, allowing us to compute rolling motion referenced to the artificial climbing wall. Information on ascent duration, the number of exploratory and performatory movements for locating hand-holds, and hip path was also observed in video footage from a frontal camera worn by participants. Climbing fluency was assessed by calculating geometric index of entropy. Results showed that the meta-stable condition of performance may have afforded utilization of more adaptive climbing behaviors (expressed in higher values for range and variability of trunk rolling motion and greater number of exploratory movements). Findings indicated how climbers learn to explore and, subsequently, use effective exploratory search strategies that can facilitate transfer of learning to performance in novel climbing environments.
... Equally, whilst scoring systems are used in competition events, where scores are determined by outcomes such as how far (high) participants achieve on an ascent of a route and the number of holds used 12 , information on the quality of ascents such as the execution of skilled movement and tactical components are not part of such measures. The same is also true with the application of time-motion analysis 13,14 , and indices of the fluency of the displacement of climbers centre of mass, such as the geometric index of entropy 15,16 . As a result, in order to gain further insight into the quality of climbing performance, several studies have attempted to analyse the technical and tactical factors through the design and validation of observational tools [17][18][19] . ...
... Geometric Entropy. It is possible to quantify the fluency of movement through the analysis of the path of the centre of mass of a climber over the course of an ascent, the geometric index of entropy quantifies the paths relative complexity 15,16 . The x and y coordinates of the climbers' position was digitised throughout their ascent of the route. ...
... A single point on the middle back of the harness was chosen as an approximation of the climber's centre of mass to represent the climbers' displacement over the entire route 28 . Several studies have used the single-point path of the centre of mass 11,15,16,25,28 . The chosen point was manually digitalised into x and y coordinates using Tracker (Version 4.92; Open Source Physics). ...
Article
Purpose: To assess the validity and reliability of a novel movement-performance assessment tool for climbing/sport climbing. Methods: First, salient climbing movement-performance factors were identified through an iterative consultation process with 10 expert climbing coaches; the resulting Climber's Movement Performance Assessment Tool (CM-PAT) contained 14 items in 5 categories. Second, 61 intermediate to advanced climbers ascended a single route, which was video recorded. Subsequently, 4 experienced (>10 y coaching) coaches used the CM-PAT to observe and score the climbers' performance. Interrater reliability and comparisons with existing measures of climbing performance (6-mo self-reported ability, success and failure, climbing pace [m·min-1], and geometric entropy) were made. Results: Intraclass correlation coefficient (2,k) for the 4 raters demonstrated excellent reliability (>.81) between observers and good to excellent test-retest reliability (.71-.91). Pearson correlations between self-reported ability and CM-PAT scores explained 61% of the variance in self-reported climbing performance compared with 16% for geometric entropy and 52% for climbing pace. Considering differences in successful and unsuccessful climbers, the CM-PAT (P < .0005; d = 2.14), geometric entropy (P = .014; d = 0.67), and pace (P < .0005; d = 1.88) were able to differentiate between groups. Conclusions: The CM-PAT is the first sport climbing performance observational instrument to be developed through a thorough iterative process with expert coaches. Excellent interrater and test-retest reliability and excellent agreement with self-reported ability and with existing quantitative measures of performance support its recommendation for use in coaching and research contexts. Notably, a key advantage over existing measures is the identification of coachable elements of performance.
... Equally, whilst scoring systems are used in competition events, where scores are determined by outcomes such as how far (high) participants achieve on an ascent of a route and the number of holds used 12 , information on the quality of ascents such as the execution of skilled movement and tactical components are not part of such measures. The same is also true with the application of time-motion analysis 13,14 , and indices of the fluency of the displacement of climbers centre of mass, such as the geometric index of entropy 15,16 . As a result, in order to gain further insight into the quality of climbing performance, several studies have attempted to analyse the technical and tactical factors through the design and validation of observational tools [17][18][19] . ...
... Geometric Entropy. It is possible to quantify the fluency of movement through the analysis of the path of the centre of mass of a climber over the course of an ascent, the geometric index of entropy quantifies the paths relative complexity 15,16 . The x and y coordinates of the climbers' position was digitised throughout their ascent of the route. ...
... A single point on the middle back of the harness was chosen as an approximation of the climber's centre of mass to represent the climbers' displacement over the entire route 28 . Several studies have used the single-point path of the centre of mass 11,15,16,25,28 . The chosen point was manually digitalised into x and y coordinates using Tracker (Version 4.92; Open Source Physics). ...
Article
Full-text available
Purpose: To assess the validity and reliability of a novel movement performance assessment tool for climbing/sport climbing. Methods: Firstly, salient climbing movement performance factors were identified through an iterative consultation process with ten expert climbing coaches; the resulting Climber’s Movement Performance Assessment Tool (CM-PAT) contained 14 items in five categories. Secondly, 61 intermediate to advanced climbers ascending a single route, which was video recorded. Subsequently, four experienced (>10 years coaching) coaches used the CM-PAT to observe and score the climbers performance. Inter-rater reliability and comparisons with existing measures of climbing performance (six-month self-reported ability, success and failure, climbing pace [m.min-1] and geometric entropy [GE]) were made. Results: Intra-Class Correlation Coefficient (ICC 2,k), for the four raters demonstrated excellent reliability (>0.81) between observers, and good to excellent test – retest reliability (0.71 – 0.91). Pearson’s correlations between self-reported ability and CM-PAT scores explained 61% variance in self-reported climbing performance compared to 16% for GE and 52% for climbing pace. Considering differences in successful and unsuccessful climbers, the CM-PAT (p < .0005; d = 2.14), GE (p = .014; d = .67) and pace (p < .0005; d = 1.88) were able to differentiate between groups. Conclusion: The CM-PAT is the first sport climbing performance observational instrument to be developed through a thorough iterative process with expert coaches. Excellent inter-rater and test-retest reliability and excellent agreement with self-reported ability existing quantitative measures of performance, support its recommendation for use in coaching and research contexts. Notably, a key advantage over existing measures is the identification of coachable elements of performance.
... Climbability depends on the relation between the characteristics of an approximately vertical surface and its layout (e.g., holds for the hands and feet) and that of an individual, which constrain her/his reaching, grasping and using holds as the basis for quadrupedal locomotion. Importantly, rock climbing does not only correspond to continuous upward body displacements, but also includes stationary positions dedicated to exploring and grasping surface holds ( Pijpers et al., 2006;Sibella et al., 2007), postural regulation ( Bourdin et al., 1998Bourdin et al., , 1999) and route finding (Cordier et al., 1993(Cordier et al., , 1994. Route finding skill reveals the ability of climbers to adapt to the ever- changing structural and functional features of the climbing wall ( Cordier et al., 1993Cordier et al., , 1994, in order to explore actions, including opportunities to grasp a hold in a certain way (e.g., crimp, pinch, slope) and to use the hold within a particular coordination mode (e.g., arm crossing or dual grasping on the same hold; ). ...
... Importantly, rock climbing does not only correspond to continuous upward body displacements, but also includes stationary positions dedicated to exploring and grasping surface holds ( Pijpers et al., 2006;Sibella et al., 2007), postural regulation ( Bourdin et al., 1998Bourdin et al., , 1999) and route finding (Cordier et al., 1993(Cordier et al., , 1994. Route finding skill reveals the ability of climbers to adapt to the ever- changing structural and functional features of the climbing wall ( Cordier et al., 1993Cordier et al., , 1994, in order to explore actions, including opportunities to grasp a hold in a certain way (e.g., crimp, pinch, slope) and to use the hold within a particular coordination mode (e.g., arm crossing or dual grasping on the same hold; ). Therefore, rock climbing is a complex form of locomotion as it involves interspersed periods of perceptual-motor exploration for route finding Seifert et al., 2017) with combinations of upper and lower limb movements to ascend the surface safely and fluently (Nougier et al., 1993;Sibella et al., 2007). ...
... Although exploration is proposed to play an important role in practice and development, spending an excessive time stationary for route finding, hold exploration or postural regulation may clearly compromise climbing fluency (Cordier et al., 1993(Cordier et al., , 1994Seifert et al., 2014a). Recently, Orth et al. (2017b) suggested the idea that individuals shift toward variables for the perception of affordances that support more fluent climbing, but this hypothesis remains not tested experimentally. ...
Article
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The aim of this study was to investigate how the affordances of an indoor climbing wall changed for intermediate climbers following a period of practice during which hold orientation was manipulated within a learning and transfer protocol. The learning protocol consisted of four sessions, in which eight climbers randomly ascended three different routes of fixed absolute difficulty (5c on the French scale), as fluently as possible. All three routes were 10.3 m in height and composed of 20 hand-holds at the same locations on an artificial climbing wall; only hold orientations were altered: (i) a horizontal-edge route (H) was designed to afford horizontal hold grasping, (ii) a vertical-edge route (V) afforded vertical hold grasping, and (iii), a double-edge route (D) was designed to afford both horizontal and vertical hold grasping. Five inertial measurement units (IMU) (3D accelerometer, 3D gyroscope, 3D magnetometer) were attached to the hip, feet and forearms to analyze the vertical acceleration and direction (3D unitary vector) of each limb and hip in ambient space during the entire ascent. Segmentation and classification processes supported detection of movement and stationary phases for each IMU. Depending on whether limbs and/or hip were moving, a decision tree distinguished four states of behavior: stationary (absence of limb and hip motion), hold exploration (absence of hip motion but at least one limb in motion), hip movement (hip in motion but absence of limb motion) and global motion (hip in motion and at least one limb in motion). Results showed that with practice, the learners decreased the relative duration of hold exploration, suggesting that they improved affordance perception of hold grasp-ability. The number of performatory movements also decreased as performance increased during learning sessions, confirming that participants' climbing efficacy improved as a function of practice. Last, the results were more marked for the H route, while the D route led to longer relative stationary duration and a shorter relative duration of performatory states. Together, these findings emphasized the benefit of manipulating task constraints to promote safe exploration during learning, which is particularly relevant in extreme sports involving climbing tasks.
... In the emergence of skilled behaviour, three timescales of change (slow, moderately fast and fast) appear to exist. According to Cordier et al. (1993), 'fast' variables account for the dynamics of motor performance. Changes in the fast timescale, typically expressed in seconds, are observed as the temporary (re)organization of behaviours in a discrete performance trial. ...
... Changes in the fast timescale, typically expressed in seconds, are observed as the temporary (re)organization of behaviours in a discrete performance trial. 'Moderately fast' variables, account for learning, refer to the relatively persistent adaptation of the individual to the environment, in a timescale perhaps expressed over several hours (Cordier, Mendès-France, Bolon, & Pailhous, 1993). The effects of learning can be observed over many performance repetitions (referred to as learning dynamics) and under retention and transfer conditions (Davids, Button, & Bennett, 2008). ...
... The effects of learning can be observed over many performance repetitions (referred to as learning dynamics) and under retention and transfer conditions (Davids, Button, & Bennett, 2008). Finally, Cordier et al. (1993) defined 'slow' variables to account for the dynamics underlying the emergence of highly skilled behaviours. This timescale may be expressed across many months or years, and can be reflected in the structural/ functional adaptations developed through progressive training (e.g. ...
... These biomechanical and physiological aspects of form have been well summarised in Chapters 2, 6, and 7. Another attempt was to assess the perceptive and cognitive aspects of form (e.g. route finding) through climbing fluency that indicates efficiency of the path taken through the route (Cordier, Mendès-France, Bolon, & Pailhous, 1993;Cordier, Mendès-France, Pailhous, & Bolon, 1994). Perceptive and cognitive aspects of form are particularly meaningful for on-sight climbing. ...
... In that case, exhibiting continuous climbing using a straightforward path through a route can be qualitatively described as 'fluent climbing' and globally captures skilled climbing performance. Relevant analyses include climb distance (Green & Helton, 2011;Seifert, Orth, et al., 2014;Seifert, Wattebled, et al., 2014), hand movement distance (Nieuwenhuys et al., 2008), centre of mass to wall distance (Sibella et al., 2007;Zampagni, Brigadoi, Schena, Tosi, & Ivanenko, 2011), inter-limb relative positions (Seifert et al., 2013c(Seifert et al., , 2014bSeifert, Coeurjolly, Hérault, Wattebled, & Davids, 2013), but the most prominent computation is of the geometric entropy index value from the hip displacement (Boschker & Bakker, 2002;Boschker, Bakker, & Michaels, 2002a;Cordier et al., 1993Cordier et al., , 1994Sanchez et al., 2012;Sibella et al., 2007). The geometric index of entropy (H) has been calculated by recording the path distance covered by the hips (L) and the perimeter of the convex hull around that path (c), according to the following equation (Cordier et al., 1993(Cordier et al., , 1994: H = logn2L/c. ...
... Relevant analyses include climb distance (Green & Helton, 2011;Seifert, Orth, et al., 2014;Seifert, Wattebled, et al., 2014), hand movement distance (Nieuwenhuys et al., 2008), centre of mass to wall distance (Sibella et al., 2007;Zampagni, Brigadoi, Schena, Tosi, & Ivanenko, 2011), inter-limb relative positions (Seifert et al., 2013c(Seifert et al., , 2014bSeifert, Coeurjolly, Hérault, Wattebled, & Davids, 2013), but the most prominent computation is of the geometric entropy index value from the hip displacement (Boschker & Bakker, 2002;Boschker, Bakker, & Michaels, 2002a;Cordier et al., 1993Cordier et al., , 1994Sanchez et al., 2012;Sibella et al., 2007). The geometric index of entropy (H) has been calculated by recording the path distance covered by the hips (L) and the perimeter of the convex hull around that path (c), according to the following equation (Cordier et al., 1993(Cordier et al., , 1994: H = logn2L/c. The geometric entropy measures reveal the amount of fluency/curvature of a curve: the higher the entropy, the higher the disorder of the system (Cordier et al., 1993(Cordier et al., , 1994. ...
... Temporal assessment quantifies the number and nature of stoppages relative to continuous climbing, indicating the amount of time spent in isometric contraction (Billat et al., 1995;White and Olsen, 2010). Spatial indicators highlight the efficiency of a climber's trajectory across the surface, estimating the ability to perceive an efficient "pathway" through the route (Cordier et al., 1993;. Finally, combined spatiotemporal measures, such as the minimization of jerk, globally indicate how smoothly climbing movements are linked together (Seifert et al., 2014b). ...
... Spatial indicators relate to analyses of displacement on a surface. Existing approaches include computation of the geometric index of entropy (GIE, see equation 1 below) (Cordier et al., 1993(Cordier et al., , 1994aPijpers et al., 2003;Sibella et al., 2007;Sanchez et al., 2010;Seifert et al., 2015;Watts et al., 2016;Orth et al., 2017), climb distance (Green and Helton, 2011;Seifert et al., 2013bSeifert et al., , 2014cGreen et al., 2014), average movement distance (Nieuwenhuys et al., 2008), COM-to-wall distance (Zampagni et al., 2011), and planar displacement of the COM (Zampagni et al., 2011). Interpreting the quality of displacement with respect to a route is the main reason GIE has enjoyed widespread application (Cordier et al., 1993(Cordier et al., , 1994aPijpers et al., 2003;Sibella et al., 2007;Sanchez et al., 2010;Seifert et al., 2017). ...
... Existing approaches include computation of the geometric index of entropy (GIE, see equation 1 below) (Cordier et al., 1993(Cordier et al., , 1994aPijpers et al., 2003;Sibella et al., 2007;Sanchez et al., 2010;Seifert et al., 2015;Watts et al., 2016;Orth et al., 2017), climb distance (Green and Helton, 2011;Seifert et al., 2013bSeifert et al., , 2014cGreen et al., 2014), average movement distance (Nieuwenhuys et al., 2008), COM-to-wall distance (Zampagni et al., 2011), and planar displacement of the COM (Zampagni et al., 2011). Interpreting the quality of displacement with respect to a route is the main reason GIE has enjoyed widespread application (Cordier et al., 1993(Cordier et al., , 1994aPijpers et al., 2003;Sibella et al., 2007;Sanchez et al., 2010;Seifert et al., 2017). ...
Article
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In this review of research on climbing expertise, we focus on different measures of climbing performance, including spatiotemporal measures related to fluency and activity states (i.e., discrete actions), adopted by climbers for achieving overall performance goals of getting to the end of a route efficiently and safely. Currently, a broad range of variables have been reported, however, many of these fail to capture how climbers adapt to a route whilst climbing. We argue that spatiotemporal measures should be considered concurrently with evaluation of activity states (such as reaching or exploring) in order gain a more comprehensive picture of how climbers successfully adapt to a route. Spatial and temporal movement measures taken at the hip are a traditional means of assessing efficiency of climbing behaviors. More recently, performatory and exploratory actions of the limbs have been used in combination with spatiotemporal indicators, highlighting the influence of limb states on climbing efficiency and skill transfer. However, only a few studies have attempted to combine spatiotemporal and activity state measures taken during route climbing. This review brings together existing approaches for observing climbing skill at performance outcome (i.e., spatiotemporal assessments) and process (i.e., limb activity states) levels of analysis. Skill level is associated with a spatially efficient route progression and lower levels of immobility. However, more difficult hold architecture designs require significantly greater mobility and more complex movement patterning to maintain performance. Different forms of functional, or goal-supportive, movement variability, including active recovery and hold exploration, have been implicated as important adaptations to physiological and environmental dynamics that emerge during the act of climbing. Indeed, recently it has also been shown that, when climbing on new routes, efficient exploration can improve the transfer of skill. This review provides new insights into how climbing performance and related actions can be quantified to better capture the functional role of movement variability.
... 696) (blood lactate concentration and EMG) because a higher muscle tension would have to result in more muscle fatigue (Vincken & Denier van der Gon, 1985). In Experiment 2 we ask whether the expected muscle tension at the physiological level has repercussions for the smoothness of movement execution at the behavioural level as measured with the 'geometric index of entropy' (Cordier, Mendès France, Bolon, & Pailhous, 1993;Cordier, Mendès France, Pailhous, & Bolon, 1994), a variable we will explain in the introduction to Experiment 2 and that may be connected conceptually to the notion of active dynamical degrees of freedom introduced before. As a result of the higher muscle tension we expected jerkier, more rigid movements in anxiety provoking than in anxiety-neutral situations, and, therefore, a higher geometric index of entropy. ...
... In Experiment 2 we examined whether anxiety is also accompanied by rigid and jerky movements as would be expected if a regress to lower skill levels occurs. In order to do so we measured the fluency of participants' climbing movements by using a 'geometric index of entropy' (Cordier et al., 1993(Cordier et al., , 1994. Just as the complexity of a spatial-temporal trajectory may be assessed by means of its dimensionality, the geometric index of entropy (in short, 'entropy') can be used to assess the complexity of a spatial trajectory, or path (Cordier et al., 1993(Cordier et al., , 1994. ...
... In order to do so we measured the fluency of participants' climbing movements by using a 'geometric index of entropy' (Cordier et al., 1993(Cordier et al., , 1994. Just as the complexity of a spatial-temporal trajectory may be assessed by means of its dimensionality, the geometric index of entropy (in short, 'entropy') can be used to assess the complexity of a spatial trajectory, or path (Cordier et al., 1993(Cordier et al., , 1994. In sport climbing the entropy can be defined as the fluency of the curvature that arises from the displacement of the body centre of gravity when climbing a route (Cordier et al., 1993(Cordier et al., , 1994; see Figure 2.2). ...
... Fluency could be captured by spatial (e.g. geometric index of entropy [14]), temporal (e.g., ratio between immobility and motion [15]) and spatial-temporal measurements (e.g., jerk coefficient corresponding to the smoothness of the hip displacement [13])-for a review, see [16]. ...
... If they chose to take less than three minutes they indicated this to the experimenter. They were told to selfpace their ascent and climb as fluently possible, i.e., without falling down and by minimizing pauses and rest periods of body displacement during the ascent [4,13,14]; noting that speed (i.e., climbing fast) is not a criteria of fluency. We did not give specific instructions so that perception and action processes could emerge during exploratory behaviour during the preview and follow-up climb. ...
... Route finding skill requires "a series of well-formed movements which are linked together into actual 'sentences' and serve to structure the climber's motor behavior" (p. 371) [14]. In other words it entails rapidly and correctly find the climbing path [13,14,37] and the way to grasp holds [4,6]. ...
Article
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This study examined the role of route previewing strategies on climbing fluency and on exploratory movements of the limbs, in order to understand whether previewing helps people to perceive and to realize affordances. Eight inexperienced and ten experienced climbers previewed a 10 m high route of 5b difficulty on French scale, then climbed it with a top-rope as fluently as possible. Gaze behavior was collected from an eye tracking system during the preview and allowed us to determine the number of times they scanned the route, and which of four route previewing strategies (fragmentary, ascending, zigzagging, and sequence-of-blocks) they used. Five inertial measurement units (IMU) (3D accelerometer, 3D gyroscope, 3D magnetometer) were attached to the hip, both feet, and forearms to analyze the vertical acceleration and direction of each limb and hip during the ascent. We were able to detect movement and immobility phases of each IMU using segmentation and classification processes. Depending on whether the limbs and/or hip were moving, five states of behavior were detected: immobility, postural regulation, hold exploration, hold change, and hold traction. Using cluster analysis we identified four clusters of gaze behavior during route previewing depending on route preview duration, number of scan paths, fixations duration, ascending, zigzagging, and sequence-of-blocks strategies. The number of scan paths was positively correlated with relative duration of exploration and negatively correlated with relative duration of hold changes during the ascent. Additionally, a high relative duration of sequence-of-blocks strategy and zigzagging strategy were associated with a high relative duration of immobility during the ascent. Route previewing might help to pick up functional information about reachable, graspable, and usable holds, in order to chain movements together and to find the route. In other words, route previewing might contribute to perceiving and realizing nested affordances.
... To obtain an indication of muscle tension, we used muscle fatigue (blood lactate concentration and EMG) because a higher muscle tension would have to result in more muscle fatigue (Vincken & Denier van der Gon, 1985). In Experiment 2 we ask whether the expected muscle tension at the physiological level has repercussions for the smoothness of movement execution at the behavioural level as measured with the "geometric index of entropy" (Cordier, Mendès France, Bolon, & Pailhous, 1993;Cordier, Mendès France, Pailhous, & Bolon, 1994), a variable we will explain in the introduction to Experiment 2 and that may be connected conceptually to the notion of active dynamical degrees of freedom introduced before. As a result of the higher muscle tension we expected jerkier, more rigid movements in anxiety-provoking than in anxiety-neutral situations, and, therefore, a higher geometric index of entropy. ...
... In Experiment 2 we examined whether anxiety is also accompanied by rigid and jerky movements as would be expected if a regress to lower skill levels occurs. In order to do so we measured the fluency of participants' climbing movements by using a "geometric index of entropy" (Cordier et al., 1993(Cordier et al., , 1994. Just as the complexity of a spatialtemporal trajectory may be assessed by means of its dimensionality, the geometric index of entropy (in short, "entropy") can be used to assess the complexity of a spatial trajectory, or path (Cordier et al., 1993(Cordier et al., , 1994. ...
... In order to do so we measured the fluency of participants' climbing movements by using a "geometric index of entropy" (Cordier et al., 1993(Cordier et al., , 1994. Just as the complexity of a spatialtemporal trajectory may be assessed by means of its dimensionality, the geometric index of entropy (in short, "entropy") can be used to assess the complexity of a spatial trajectory, or path (Cordier et al., 1993(Cordier et al., , 1994. In sport climbing the entropy can be defined as the fluency of the curvature that arises from the displacement of the body centre of gravity when climbing a route (Cordier et al., 1993(Cordier et al., , 1994see Fig. 2). ...
Article
Objectives: Two experiments were conducted to investigate manifestations of anxiety at the subjective, physiological, and behavioural level of analysis.Design: In Experiment 1 we investigated the manifestations of state anxiety at the first two levels by comparing low- and high-anxiety conditions during climbing. In Experiment 2 we explored behavioural differences under these conditions.Methods: We manipulated anxiety by using a climbing wall with routes defined at different heights (low and high). Participants were 13 and 17 novice climbers in Experiments 1 and 2, respectively (ages 19–30 years). We measured self-reported state anxiety, heart rate (Experiments 1 and 2), blood lactate concentration and muscle fatigue (Experiment 1), and climbing time and fluency of movements (Experiment 2).Results: At the level of subjective experience we found that when novices climbed a route high on a climbing wall they reported significantly more anxiety than when they traversed an identical route low on the climbing wall. At the physiological level, they exhibited significantly higher heart rates, more muscle fatigue, and higher blood lactate concentrations. The results of Experiment 2 showed that state anxiety also affected participants’ movement behaviour, which was evidenced by an increased geometric index of entropy and by longer climbing times.Conclusions: Results indicated that anxiety indeed manifested itself at three levels. A possible explanation for the effects of anxiety that is also found in the literature is that a temporary regress may occur to a movement execution that is associated with earlier stages of motor learning.
... Spatial measurement analyses mainly corresponded to computations of the geometric entropy index value from the displacement of the hips. 7,[13][14][15][16] The geometric index of entropy (H) was calculated by recording the distance path covered by the hips (L) and the perimeter of the convex hull around that path (c) according to the following equation: 14,15 H = log n 2L/c . (1) According to Cordier et al, 14,15 geometric entropy measures reveal the amount of fluency or curvature of a curve. ...
... Spatial measurement analyses mainly corresponded to computations of the geometric entropy index value from the displacement of the hips. 7,[13][14][15][16] The geometric index of entropy (H) was calculated by recording the distance path covered by the hips (L) and the perimeter of the convex hull around that path (c) according to the following equation: 14,15 H = log n 2L/c . (1) According to Cordier et al, 14,15 geometric entropy measures reveal the amount of fluency or curvature of a curve. ...
... 7,[13][14][15][16] The geometric index of entropy (H) was calculated by recording the distance path covered by the hips (L) and the perimeter of the convex hull around that path (c) according to the following equation: 14,15 H = log n 2L/c . (1) According to Cordier et al, 14,15 geometric entropy measures reveal the amount of fluency or curvature of a curve. The higher the entropy, the higher the disorder of the system; therefore, a low entropy value was associated with a low energy expenditure and greater climbing fluency. ...
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This study investigated a new performance indicator to assess climbing fluency (smoothness of the hip trajectory and orientation of a climber using normalized jerk coefficients) in order to explore effects of practice and hold design on performance. Eight experienced climbers completed 4 repetitions of two, 10-m high routes with similar difficulty levels, but varying in hold graspability (holds with one edge vs. holds with two edges). An inertial measurement unit was attached to the hips of each climber to collect 3D acceleration and 3D orientation data in order to compute jerk coefficients. Results showed high correlations (r = .99, P<.05) between the normalized jerk coefficient of hip trajectory and orientation. Results showed higher normalized jerk coefficients for the route with two graspable edges, perhaps due to more complex route finding and action regulation behaviours. This effect decreased with practice. Jerk coefficient of hip trajectory and orientation could be a useful indicator of climbing fluency for coaches as its computation takes into account both spatial and temporal parameters, i.e., changes in both climbing trajectory and time to travel this trajectory.
... Therefore, the designated climbing task corresponded to a sub-maximal grade of difficulty for the participants, which prevented any possible fatigue effects during each testing session. They had the following task-goal: to find the way to climb up the surface as fluently possible, i.e., without falling down and by minimizing pauses and rest periods of body displacement during the ascent (Cordier et al., 1993(Cordier et al., , 1994Seifert et al., 2014b). Instructions were not made too specific to allow coordination patterns to emerge as each climber exhibited exploratory behaviors under the varying task constraints. ...
... Frontiers in Psychology | www.frontiersin.org to climb with highest fluency, the climbing fluency of the hip trajectory was assessed by the geometric index of entropy (GIE) (Cordier et al., 1993(Cordier et al., , 1994Sibella et al., 2007). GIE was calculated by recording the distance path covered by the hip (L) and the perimeter of the convex hull around that path (c) according to the following equation (Cordier et al., 1993(Cordier et al., , 1994: GIE = logn2L/c. ...
... to climb with highest fluency, the climbing fluency of the hip trajectory was assessed by the geometric index of entropy (GIE) (Cordier et al., 1993(Cordier et al., , 1994Sibella et al., 2007). GIE was calculated by recording the distance path covered by the hip (L) and the perimeter of the convex hull around that path (c) according to the following equation (Cordier et al., 1993(Cordier et al., , 1994: GIE = logn2L/c. According to Cordier et al. (1993Cordier et al. ( , 1994, the geometric index of entropy measures reveal the amount of fluency/curvature of a curve. ...
... During route preview, climbers visually inspect a route from the ground to consider how to coordinate their actions with respect to important surface properties of the holds and wall [38,40,41]. During climbing, individuals coordinate their actions with respect to features of the climbing surface by forming relationships between limbs [42] and surface properties [43,44], which are regulated over time to complete the route [45]. Coordination can also be classified across different levels: coordination between limbs is called intra-personal coordination, coordination between individuals is called inter-personal coordination and coordination between individuals and their environment is called extra-personal coordination [46]. ...
... General Specific Task Instruction Required climbing speed [92]; use of specific gripping technique [52], reaching action [68], postural position [47] and/or movement pattern [43]; attending to additional foci [84]; self-preferred [94]; competition event [54]; application of maximal force [67] Route safety demands Lead-rope (existing bolts) [36]; top-rope [66]; bouldering (safety mats, no-rope) [98]; roped Route practice On-sight [54]; second attempt [24]; after practice [45] Route preview ...
... As highlighted earlier, skill differences can uncover important adaptations, many of which can appear counterintuitive. Skill differences discussed in the following section pertain to preview tasks [38,40] and relationships between coordination and climbing fluency [26,39,45,48,79,80,95]. ...
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Background Climbing is a physical activity and sport involving many subdisciplines. Minimization of prolonged pauses, use of a relatively simple path through a route and smooth transitions between movements broadly define skilled coordination in climbing. Objectives To provide an overview of the constraints on skilled coordination in climbing and to explore future directions in this emerging field. Methods A systematic literature review was conducted in 2014 and retrieved studies reporting perceptual and movement data during climbing tasks. To be eligible for the qualitative synthesis, studies were required to report perceptual or movement data during climbing tasks graded for difficulty. Results Qualitative synthesis of 42 studies was carried out, showing that skilled coordination in climbing is underpinned by superior perception of climbing opportunities; optimization of spatial–temporal features pertaining to body-to-wall coordination, the climb trajectory and hand-to-hold surface contact; and minimization of exploratory behaviour. Improvements in skilled coordination due to practice are related to task novelty and the difficulty of the climbing route relative to the individual’s ability level. Conclusion Perceptual and motor adaptations that improve skilled coordination are highly significant for improving the climbing ability level. Elite climbers exhibit advantages in detection and use of climbing opportunities when visually inspecting a route from the ground and when physically moving though a route. However, the need to provide clear guidelines on how to improve climbing skill arises from uncertainties regarding the impacts of different practice interventions on learning and transfer.
... Average speed (in meter per second) that is, the ratio between the distance covered by a participant in corridors A and B and the time she/he spent in the corridors A and B. Standard deviation (SD) of speed (in meter per second) defined as speed variability in corridors A and B. Trajectory variability or geometric index of entropy (in short ''entropy") that is ''the fluency of the curvature that arises from the displacement" of the participants when moving inside the VEs (Pijpers et al., 2003, p. 293). Pailhous (1993), Cordier, Mendès France, Pailhous, andBolon (1994) described entropy (H) by the following equation: H = log n (2L/c), where L is the length of the curve or the distance (in meter) covered by a participant during his/her displacement in corridors A and B, and c the convex hull (envelope, in meters) of that curve. 3 According to these authors, a less fluent participants' displacement will give rise to a higher index of entropy. ...
... For more description about entropy development seeCordier et al. (1993Cordier et al. ( , 1994. ...
Article
This study investigated the impact of an aversive environmental stimulation on self-reported affective and anxiety states and movement behaviors during a simulated navigation task in a virtual environment (VE). In the experimental task, participants were asked to virtually navigate (within two consecutive sessions), from a starting point to a destination location, across a spatial configuration consisting in three successive corridors (A–C). In the first session, all corridors were non-aversive. In the second session, the corridor B contained an aversive stimulation (i.e., fire, smokescreen, and warning alarm). Fourteen participants were involved in the experiment. Self-reported anxiety and affective states were measured at the end of each session. However, movement indicators (i.e., execution, time, average speed, speed and trajectory variability) were recorded on-line during the experiment. Results showed a significant increased (i) level of self-reported negative affects and state-anxiety between the two sessions, and (ii) speed and trajectory variability between the two sessions, while the participants were in corridor B. In conclusion, these results support the experimental validity of virtual reality for the induction of negative affects and state-anxiety. The relationships between reported negative affects and state-anxiety and behavior are discussed.
... The sport of rock climbing requires the use of both upper and lower limbs, as climbers reach and grasp holds and use their feet to climb the rock surface. Yet rock climbing encompasses more than continuous upward body movement, because more or less static positions are also crucial for exploring and grasping surface holds [1][2][3], posture regulation [4][5][6][7], arm release and resting [8], and finding routes [9][10]. The time spent in exploration and posture regulation as opposed to ascending, or more broadly the time spent immobile as opposed to in motion, can be analysed by quantifying the durations when the pelvis is and is not in motion [11][8][12][13]. ...
... This suggests that during stops climbers may exhibit behaviours that are dedicated to more than managing fatigue. Ascending requires skills in route finding, which reveals the ability of climbers to interpret the everchanging structure of the climbing wall design [9][10]. Route finding is a critical climbing skill that can be identified by differentiating exploratory movements and performatory movements [2]. ...
Article
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This paper presents a novel application of a machine learning method to automatically detect and classify climbing activities using inertial measurement units (IMUs) attached to the wrists, feet, and pelvis of the climber. This detection/classification can be useful for research in sport science to replace manual annotation where IMUs are becoming common. Detection requires a learning phase with manual annotation to construct statistical models. Full-body activity is then classified based on the detection of each IMU.
... Speed and more generally effective performance are related to the ability of climbers to chain movements in a fluent manner by minimising jerky movements, i.e., with saccades and stoppages (Cordier et al., 1993(Cordier et al., , 1994Orth et al., 2017;. Indeed, recent findings showed that after 14 sessions over 7 weeks of practice, novice climbers improved their climbing time and fluency by decreasing time spent immobile, entropy of hip displacement and jerky movement . ...
... Previous research investigated climbing fluency mainly by considering the jerk and the entropy of hip or centre of mass trajectory (Cordier et al., 1993;Sibella et al., 2007;Zampagni et al., 2011), while few researchers paid attention to the contribution of feet and hands to climbing fluency (Boulanger et al., 2016;Ladha et al., 2013;Seifert et al., 2018). Although some studies distinguished exploratory and performatory actions of hands (Nieuwenhuys et al., 2008;Pijpers et al., 2006;Seifert et al., 2015Seifert et al., , 2018, implications of our study are that crucial information about hands and feet contact time on hold are provided with this new instrumentedholds system, in order to identify crux points for each climber and differences of climbing fluency dynamics between climbers. ...
Article
The aim of this study was to investigate the hold-by-hold climbing fluency dynamics by using an instrumented holds system that measured the contact time on each hold. Forty-four competitive climbers have been analysed in a regional lead climbing competition during a route composed of 41 instrumented holds on 11 m high artificial climbing wall and with a grade of difficulty 6b on the French scale (IRCRA reported scale: 13). After removing 10 climbers who fell before the top of the route, the 34 remaining climbers who completed the route were clustered according to their total contact time on each hold. The hierarchical cluster analysis distinguished four profiles of climbing fluency dynamics, on the basis of six ‘crux’ points, showing that the fastest climbers at the crux points were those with the shortest climbing time. This new instrumented-holds system appeared very innovative as it provides an instantaneous feedback to coaches regarding inter-limbs fluency and subsequent motor organisations.
... The index of the geometric Entropy (GE) is a ratio between the length of a trajectory and the perimeter length of its convex hull (Cordier et al. 1993). For a given trajectory from time 0 to time T , x : [O, T ] → R 3 , let's be Δx the trajectory length and Δc(x) the convex hull perimeter. ...
Article
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This paper reports the results of two studies carried out in a controlled environment aiming to understand relationships between movement patterns of coordination that emerge during climbing and performance outcomes. It involves a recent method of nonlinear dimensionality reduction, multi-scale Jensen–Shannon neighbor embedding (Lee et al., 2015), which has been applied to recordings of movement sensors in order to visualize coordination patterns adapted by climbers. Initial clustering at the climb scale provides details linking behavioral patterns with climbing fluency/smoothness (i.e., the performance outcome). Further clustering on shorter time intervals, where individual actions within a climb are analyzed, enables more detailed exploratory data analysis of behavior. Results suggest that the nature of individual learning curves (the global, trial-to-trial performance) corresponded to certain behavioral patterns (the within trial motor behavior). We highlight and discuss three distinctive learning curves and their corresponding relationship to behavioral pattern emergence, namely: no improvement and a lack of new motor behavior emergence; sudden improvement and the emergence of new motor behaviors; and gradual improvement and a lack of new motor behavior emergence.
... A major unresolved problem surrounding skill in climbing is how to effectively understand the transfer of skill. Although practice effects have been observed (Boschker & Frank, 2002;Cordier, Dietrich, & Pailhous, 1996;Cordier, Mendès-France, Bolon, & Pailhous, 1993Seifert, Orth, et al., 2013), studies are yet to have directly considered transfer related to practice interventions. The aim of this study was to determine whether practice in a meta-stable regime supports the transfer of climbing fluency to another route. ...
Article
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Being a discipline with a broad range of genres, rock climbing is an activity where participants seek to generalize the skills they learn in different performance contexts. A training strategy for achieving skill transfer was explored in a group of experienced climbers. Specifically, we tested the effect of practising on three routes, each of the same difficulty, but where handholds supported opportunities for using either a single technical action or multiple actions. Transfer of climbing fluidity in terms of the geometric index of entropy (GIE) of the hip trajectory was then assessed. We expected that learning would be induced on the route where multiple actions were usable. Results revealed that GIE showed a learning effect only when practice was undertaken on a route designed with multiple graspable edges. Practice on the multi-functional route best explains why the participants' successfully generalized climbing fluency under transfer conditions.
... Previous works on climbing motion rely wether on 2D video analysis only or inertial measurement unit (IMU) as depicted in the literature review by Orth et al. (2017). Among first kinematical studies of climbing, Cordier et al. introduced the concept of entropy in climbing, based on the convex hull span by the trajectory of a marker on the harness (Cordier et al., 1993). For climbing motion, Seifert et al. stressed the importance of addressing motor-control issues in 3D (Seifert et al., 2014(Seifert et al., , 2015. ...
Article
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Speed climbing involves an optimization of the velocity of the ascent and the trajectory path during performance. Consequently, any amount of energy spent in the two other directions than vertical, namely the lateral direction and the direction perpendicular to the wall plane, is a potential loss of performance. To assess this principle, we present a study on 3D motion analysis and its 3D visualization for a subject during a speed climbing performance. The fundamentals of geometrical measurement in 3D require to integrate multiple 2D cues, at least two, in order to extract 3D information. First results with two drones following an athlete's ascent show that a 3D velocity profile can be provided from the tracking of a marker on the harness, pointing critical phases in the ascent where the vertical speed is not dominant any more. We further investigate 3D motion of full body using markerless video-based tracking. Our approach is based on a full body 3D avatar model of the climber, represented as a 3D mesh. This model and its deformation are learned in a laboratory studio. The learning needs to be done only once. Result is a manifold embedding of the 3D mesh and its deformations, which can be used afterwards to perform registration onto video of performance of speed climbing. The results of the tracking is an inference of the 3D mesh aligned onto videos of speed climbing performance. From this 3D mesh, we deduce an estimation of the center of mass (COM). We show that this estimation from 3D mesh differs from the usual approximation of the COM as a marker on the harness. In particular, the 3D mesh COM takes into account the whole body movement such as the influence of the limbs which is not detected by a marker on the harness.
... Excessive durations spent immobile during route finding and hold exploration may compromise climbing fluency, leading to enhanced physical and mental fatigue. Climbing fluency has been assessed previously by: (i) measuring the geometric index of entropy (Cordier, Mendès-France, Bolon, & Pailhous, 1993;Cordier, Mendès-France, Pailhous, & Bolon, 1994;Sibella, Frosio, Schena, & Borghese, 2007), (ii) the time spent in different states (movement/immobility) (Billat, Palleja, Charlaix, Rizzardo, & Janel, 1995;Seifert, Wattebled, et al., 2013;, and more recently (iii), by calculating the jerk coefficient (i.e., third time derivative of position or the rate of change of acceleration; Flash & Hogan, 1985;Hogan, 1984), previously used as an index of smoothness of 3D translations and 3D rotations of the hips (Seifert, Orth, et al., 2014). ...
Article
Using an ecological dynamics framework, this study investigated the generality and specificity of skill transfer processes in organisation of perception and action using climbing as a task vehicle. Fluency of hip trajectory and orientation was assessed using normalized jerk coefficients exhibited by participants as they adapted perception and action under varying environmental constraints. Twelve recreational climbers were divided into two groups: one completing a 10-m high route on an indoor climbing wall; a second undertaking a 10-m high route on an icefall in a top-rope condition. We maintained the same level of difficulty between these two performance environments. An inertial measurement unit was attached each climber’s hips to collect 3D acceleration and 3D orientation data to compute jerk coefficient values. Video footage was used to record the ratio of exploratory/performatory movements. Results showed higher jerk coefficient values and number of exploratory movements for performance on the icefall route, perhaps due to greater functional complexity in perception and action required when climbing icefalls, which involves use of specific tools for anchorage. Findings demonstrated how individuals solve different motor problems, exploiting positive general transfer processes enabling participants to explore the pick-up of information for the perception of affordances specific to icefall climbing.
... While the current climbing literature is not exhaustive, there are other factors that have been shown to influence and explain variance in performance, such as handgrip strength (Baláš et al. 2012), climber flexibility (Brent et al. 2009), and improved exercise economy (Baláš et al. 2014). Furthermore, these physical attributes are accompanied by technical and psychological factors, including but not limited to; an increase in efficiency of footwork (Baláš et al. 2014), capacity to produce stable movement paths (Cordier et al. 1993) and differences in the perception of affordances (Boschker et al. 2002). Thus, while forearm flexor O 2 HTR is clearly an important factor (Fig. 2), climbing ability is multi-faceted, and it should not be expected that one factor would fully explain all the variance in performance. ...
Article
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Rock-climbing performance is largely dependent on the endurance of the forearm flexors. Recently, it was reported that forearm flexor endurance in elite climbers is independent of the ability to regulate conduit artery (brachial) blood flow, suggesting that endurance is not primarily dependent on the ability of the brachial artery to deliver oxygen, but rather the ability of the muscle to perfuse and use oxygen, i.e., skeletal muscle oxidative capacity. Purpose The aim of the study was to determine whether an index of oxidative capacity in the flexor digitorum profundus (FDP) predicts the best sport climbing red-point grade within the last 6 months. Participants consisted of 46 sport climbers with a range of abilities. Methods Using near-infrared spectroscopy, the oxidative capacity index of the FDP was assessed by calculating the half-time for tissue oxygen resaturation (O2HTR) following 3–5 min of ischemia. Results Linear regression, adjusted for age, sex, BMI, and training experience, revealed a 1-s decrease in O2HTR was associated with an increase in red-point grade by 0.65 (95 % CI 0.35–0.94, Adj R 2 = 0.53). Conclusions Considering a grade of 0.4 separated the top four competitors in the 2015 International Federation Sport Climbing World Cup, this finding suggests that forearm flexor oxidative capacity index is an important determinant of rock-climbing performance.
... Information entropy is a straightforward and useful index corresponding to the content of information in models of human information processing (Quastler, 1955), and it can be used to infer the uncertainty, disorganization, or variability in a physical system (Cover & Thomas, 1991;Kay, 1957;Shannon & Weaver, 1949). Although entropy as a global variable of the learning process has been measured on the basis of geometric theory (Cordier, Mendès France, Bolon, & Pailhous, 1993;Cordier, Mendès France, Pailhous, & Bolon, 1994), its use as a reflection of uncertainty or variability in the motor system has not been directly examined. ...
Article
Information entropy and mutual information were investigated in discrete movement aiming tasks over a wide range of spatial (20-160 mm) and temporal (250-1250 ms) constraints. Information entropy was calculated using two distinct analyses: (1) with no assumption on the nature of the data distribution; and (2) assuming the data have a normal distribution. The two analyses showed different results in the estimate of entropy that also changed as a function of task goals, indicating that the movement trajectory data were not from a normal distribution. It was also found that the information entropy of the discrete aiming movements was lower than the task defined indices of difficulty (ID) that were selected for the congruence with Fitts' law. Mutual information between time points of the trajectory was strongly influenced by the average movement velocity and the acceleration/deceleration segments of the movement. The entropy analysis revealed structure to the variability of the movement trajectory and outcome that has been masked by the traditional distributional analyses of discrete aiming movements.
... Inappropriately high levels of anxiety have been shown to increase movement time, visual fixation, decrease visual search rate (Nieuwenhuys et al., 2008) and increase muscle tension (Pijpers et al., 2003). Approaches to quantify movement quality include measurement of the fluency of participants climbing movements by calculating the geometric index of entropy of the climber's trajectory (Cordier, France, Bolon, & Pailhous, 1993) and observing the proportion of time spent moving and maintaining static positions . It is thought that alterations in physical behaviour from anxiety are caused by a reduction in information processing efficiency and regression to an earlier stage of motor learning, negatively influencing a climber's movement behaviour (Nieuwenhuys et al., 2008;Pijpers et al., 2003). ...
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The sport of rock climbing places a significant physiological and psychological load on participants. Psychophysiological analysis provides a unique insight into affective states arising from the demands of climbing, and the impact that they have on performance. This review provides an overview of climbing psychophysiology research completed to date. To summarise, an on-sight lead ascent of a route elicits the greatest psychophysiological response in climbers, whilst a red-point top-rope ascent produces the least. The effects of climbing stimuli on an individual's performance appear to be conditional on their experience. In general, experienced climbers show superior performance and are less anxious than their less practiced counterparts, with significantly lower cognitive and somatic anxiety, increased self-confidence and lower values of the steroid stress hormone cortisol. It is likely that the experience–stressor–performance relationship is due to advanced climbers' greater understanding of the risks associated with the sport, their habituation to the stressors gained through practice and their ability to perform well with higher levels of anxiety. This review outlines pertinent psychological climbing stimuli, summarises current methodologies and presents a detailed review of climbing psychophysiology research. It also concludes with suggestions for improving the depth and breadth of future research, including the need for the refinement of existing measures.
... In the present study performance was examined by means of the fluency of the curve produced from the displacement of the climber's body center of gravity when climbing (geometric entropy; Cordier et al., 1993Cordier et al., , 1994 and climbing ascent times (in s). The official output performance (the climbers' route score) was also obtained. ...
Article
The purpose of the present study was to assess the relationship between pre-performance psychological states and expert performance in non-traditional sport competition. Nineteen elite male sport climbers (M=24.6, SD=4.0 years of age) completed the Competitive State Anxiety Inventory-2 and the Positive and Negative Affect Schedule before an international rock climbing competition. Climbing performances were video-recorded to calculate movement fluency (entropy) and obtain ascent times. Official route scores were also obtained. Successful climbers reported higher pre-performance levels of somatic anxiety and climbed the most difficult part of the route more slowly than their unsuccessful counterparts. The psychological states preceding elite climbing competition appeared to be an important factor in determining success, even when differences in baseline ability were taken into account.
... Also note that Crofton's formulas in [20] are used frequently in many fields. To give but a few samples: complex motor behaviour in human movements [16] (also see [17, 18]), study of human blood and transfusion [62], simulation of gravitational evolution [57], anistropies of the secondary cosmic microwave background [25], grain size distribution analysis for polycrystalline thin films [19], image analysis of crystalline agglomerates [49], measurement of convolution in cotton fibers [28], all applications of LIS (Line-Intercept Sampling), e.g., to the statistical analysis of vegetation or wildlife, see for example [63] and references therein (in particular [30] in the references below), spatial analysis of urban maps [24], in a discussion about examples of information processing coming from neurophysiology, cognitive psychology, and perception [48, pp. 1182–1185], and even relations between art and complexity [43] (also see [46, 47]). ...
Article
In order to study large variations or fluctuations of finite or infinite sequences (time series), we bring to light an 1868 paper of Crofton and the (Cauchy–)Crofton theorem. After surveying occurrences of this result in the literature, we introduce the inconstancy of a sequence and we show why it seems more pertinent than other criteria for measuring its variational complexity. We also compute the inconstancy of classical binary sequences including some automatic sequences and Sturmian sequences.
... Climbing involves strength, endurance [6], postural stability [7], technique, balance, coordination [8], route finding [9,10] and attention [11], as well as a number of psychological aspects beyond fear [12], which put high demands on the participant. Independent of the participant's level of expertise, all of the above mentioned physical and psychological abilities can continuously be challenged in climbing, because there are infinite possibilities of increasing the physical demands and challenge the participants. ...
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Background Cerebral Palsy (CP) is the most common cause of motor disabilities in children and young adults and it is also often associated with cognitive and physiological challenges. Climbing requires a multifaceted repertoire of movements, participants at all levels of expertise may be challenged functionally and cognitively, making climbing of great potential interest in (re)habilitation settings. However, until now only few research projects have investigated the feasibility of climbing as a potential activity for heightening physical activity in children with CP and the possible beneficial effects of climbing activities in populations with functional and/or cognitive challenges. The aim of this study was therefore to test the feasibility of an intensive 3 weeks indoor-climbing training program in children with CP and typically developing (TD) peers. In addition we evaluated possible functional and cognitive benefits of 3 weeks of intensive climbing training in 11 children with cerebral palsy (CP) aged 11–13 years and six of their TD peers. Method The study was designed as a feasibility and interventional study. We evaluated the amount of time spent being physically active during the 9 indoor-climbing training sessions, and climbing abilities were measured. The participants were tested in a series of physiological, psychological and cognitive tests: two times prior to and one time following the training in order to explore possible effects of the intervention. Results The children accomplished the training goal of a total of nine sessions within the 3-week training period. The time of physical activity during a 2:30 h climbing session, was comparably high in the group of children with CP and the TD children. The children with CP were physically active on average for almost 16 h in total during the 3 weeks. Both groups of participants improved their climbing abilities, the children with CP managed to climb a larger proportion of the tested climbing route at the end of training and the TD group climbed faster. For the children with CP this was accompanied by significant improvements in the Sit-to-stand test (p < 0.01), increased rate of force development in the least affected hand during an explosive pinch test and increased muscular-muscular coherence during a pinch precision test (p < 0.05). We found no improvements in maximal hand or finger strength and no changes in cognitive abilities or psychological well-being in any of the groups. Conclusions These findings show that it is possible to use climbing as means to make children with CP physically active. The improved motor abilities obtained through the training is likely reflected by increased synchronization between cortex and muscles, which results in a more efficient motor unit recruitment that may be transferred to daily functional abilities. Trial registration ISRCTN18006574; day of registration: 09/05/2017; the trial is registered retrospectively Electronic supplementary material The online version of this article (doi:10.1186/s12883-017-0889-z) contains supplementary material, which is available to authorized users.
Article
The purpose of this study was to evaluate whether observing an expert climber would enable inexperienced climbers to perceive and accomplish new possibilities for action and whether this would facilitate their climbing performance. The focus was on what information is obtained during observation of a motor action. Three groups of inexperienced male participants (N = 24) observed either a video model of an expert method of climbing, a video model of a novice method of climbing, or the climbing wall on video without a model. Participants subsequently climbed the wall. This procedure of observation followed by climbing was repeated five times. Analysis showed participants perceived and subsequently utilized information from the videotapes and that this resulted in faster and more fluent climbing (as assessed by the geometric entropy of the body center of gravity). The results are discussed in terms of perceiving and accomplishing opportunities for action or affordances.
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In 2 experiments, differences in visual perception of climbing routes (route finding) between 7 expert climbers, 4 novices, and 9 inexperienced participants were studied. In both experiments, participants reproduced on a scale model the locations and orientations of 23 holds of a climbing wall. The results showed that the expert climbers recalled more information and recalled clusters of information and that they focused on the functional aspects of a climbing wall, whereas they neglected its structural features. Inexperienced participants did not recall such clustered information, and they reported almost exclusively the structural features of the holds. The perception of nested affordances and the expert climbers' neglect of details are discussed.
Article
The work reported here is a contribution to the study of a complex motor behavior, viewed globally. The question raised is the nature of the process by which an environment-sensorimotricity coupling is organized. The material is the trajectory of a constrained free climbing task, and the main concept is entropy. The entropy of the climber's trajectory is used to measure the degree of structuring in the successive states of the subject-environment system during the learning of a complex task. It will be shown that the entropy of the trajectory decreases as learning progresses, and that the shape of the entropy curve is a function of the climber's level of expertise. A model of constraint relaxation is proposed to describe the learning process. Then, based on a theory of probabilistic inference, an attemp is made to show that this natural biological process obeys the thermodynamic laws of neural networks.
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Uncertainty in extreme sports performance environments, like rock and ice climbing, provides considerable psycho-emotional and physiological demands which challenge the acquisition of perceptual–motor skills. An ecological dynamics theoretical framework adopts concepts and tools of nonlinear dynamics and ecological psychology to investigate and model the relationships that emerge in extreme sports between athletes and their performance environments. In this relation, the interactions of athletes with key objects, surfaces, events and significant others during a sport like climbing emerge from interdependent personal, task and environmental constraints on performance. Performance behaviours emerge through the continuous and active exploration of environmental properties by individual athletes. Properties of rock cliffs, icefalls and mountains provide a high level of uncertainty due to continuous weather-driven changes. Their unpredictability signifies that performance may be considered as an ongoing coadaptation of climber’s behaviours to dynamically changing, interacting constraints, individually perceived and encountered. In this chapter, we consider the continuous interactions between climbers and their environment to understand how they can be coached to perceive key environmental properties when climbing and adapt their behaviours towards achieving performance goals.
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Rock climbers believe chalk dries the hands of sweat and improves the static coefficient of friction between the hands and the surface of the rock. The purpose of this study was to assess whether or not chalk affects geometric entropy or muscular activity during rock climbing. Nineteen experienced recreational rock climbers (13 males, 6 females; 173.5 ± 7.0 cm; 67.5 ± 3.4 kg) completed two climbing trails with and without chalk. The body position of the climber, and muscular activity of the finger flexors was recorded throughout the trial. Following the movement sequence participants hung from a standard climbing hold until they slipped from the climbing structure, while the coefficient of friction and the ratio of the vertical forces on the hand and feet were determined. Although there were no differences in the coefficient of friction (p=.748), geometric entropy (p=.359), the ratio of the vertical forces between the hands and feet (p=.570), or muscular activity (p=.968), participants were able to hang longer after the use of chalk 62.9 ± 36.7 s and 49.3 ± 25.2 s (P=.046). This is advantageous because it may allow for prolonged rests, and more time to plan the next series of climbing moves.
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Rock climbing, particularly the version known as “sport climbing,” has complex response, performance and training characteristics that make it rich for behavioral analysis and intervention. The purpose of this paper is to explore the operant characteristics of sport climbing as an endeavor in its own right, but also to illustrate the potential for behavior analysis to contribute to sport psychology in general. Accordingly we will: (a) describe sport climbing, emphasizing its behavioral demands and consensus training procedures, (b) review conventional climbing literature (e.g., training books) and research on variables affecting performance in sport climbing, and (c) describe, with supportive data, how behavioral principles and procedures could be applied conceptually to sport climbing, and (d) to suggest opportunities for operant research and practice.
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The aim of this study was to propose a method to automatically detect the different types of behavioural states in climbing. One climber traversed an easy route (5c difficulty on French scale) of 10 m height with a top-rope. Five inertial measurement units (IMU) (3D accelerometer, 3D gyroscope, 3D magnetometer) were attached to the pelvis, both feet and forearms to analyse the direction (3D unitary vector) of each limb and pelvis in ambient space. Segmentation and classification processes supported detection of movement and immobility phases for each IMU. Depending on whether limbs and/or pelvis were moving, four states of behaviour were detected: immobility (absence of limb and pelvis motion), hold exploration (absence of pelvis motion but at least one limb in motion), pelvis movement (pelvis in motion but absence of limb motion) and global motion (pelvis in motion and at least one limb in motion). Results indicated that the climber spent 10% of time immobile, 65% exploring holds, 1% with pelvis in motion (indicating posture regulation) and 24% in global movement (could indicate transition between holds). This new method allows automatic, rapid and reliable detection of climbing behavioural states to facilitate assessment and monitoring of climbing performance.
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The aim of this study was to propose a method for full-body movement pattern recognition in climbing, by computing the 3D unitary vector of the four limbs and pelvis during performance. One climber with an intermediate skill level traversed two easy routes of similar rates of difficulty (5c difficulty on French scale), 10m in height under top-rope conditions. The first route was simply designed to allow horizontal edge-hold grasping, while the second route was designed with more complexity to allow both horizontal and vertical edge-hold grasping. Five inertial measurement units (IMUs) were attached to the pelvis, both feet and forearms to analyse the 3D unitary vector of each limb and pelvis. Cluster analysis was performed to detect the number of clusters that emerged from coordination of the four limbs and pelvis during climbing performance. Analysis revealed 22 clusters with 11 clusters unique across the two routes. Six clusters were unique to the simple hold design route and five clusters emerged only in the complex hold design route. We conclude that clustering supported identification of full-body orientations during traversal, representing a level of analysis that can provide useful information for performance monitoring in climbing.
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