Staying out of range: increasing attacking distance in fencing

To avoid being hit, fencers typically adopt an out of range position, which was hypothesized to be governed by body- and action-scaled affordances. This theory was measured in elite and national level junior (u20) fencers. Associations between “reachability” of lunging and step-lunging attacks, was assessed against height, arm-span, leg-span, body mass and lower-body power, and then compared across level. Reachability was determined as the distance covered by fencers during these attacks and was reported as actual and estimated distances. Elite fencers are better at estimating their lunging and step-lunge distance compared to national ranked junior fencers (-0.9 vs. 7.3 % and 5.4 vs. 10.9 % respectively). Surprisingly, elite fencers’ actual and estimated distances for these was less than the junior fencers’ (222.6 vs. 251.5 cm and 299.3 vs. 360.2 cm respectively), and significantly so in the former. Finally only arm (r = .81) and leg span (r = .71) were significantly correlated to estimated lunging distance and this was only in elite fencers. Findings suggest that better fencers can accurately predict their attack range and that reachability appears to be positively influenced by arm and leg-span; these may feed in to talent identification. Given that distances were less in elite fencers, findings suggests that timing and distance estimation are key skills to master, and that the mastery of these in offensive actions can mitigate to a large extent, the physical benefits of an opponent’s greater height

Parking and the visual perception of space

Using measured data we demonstrate that there is an amazing correspondence among the statistical properties of spacings between parked cars and the distances between birds perching on a power line. We show that this observation is easily explained by the fact that birds and human use the same mechanism of distance estimation. We give a simple mathematical model of this phenomenon and prove its validity using measured data

The effectiveness of constraint-led training on skill development in interceptive sports: a systematic review (Clark, McEwan and Christie) – a commentary

Clark, McEwan and Christie's systematic review1 offers a timely examination of current literature assessing effects of a constraints-led approach (CLA) to training on ‘technical and cognitive skill in sport’, in comparison to traditional training methods. They concluded that, currently, there is strong evidence to advocate for the effects of training interventions that espouse benefits of constraints-led training on acquiring skill in interceptive actions. Clark, McEwan and Christie reported that 18 studies satisfied their proposed inclusion criteria and, of these studies, 77% provided evidence of the effectiveness of the CLA. Consequently, Clark, McEwan and Christie argued that a ‘the implementation of the constraints-led approach within interceptive sport can be advocated’ (p. 17). This is a revealing insight, which supports their claims that this finding ‘provides the opportunity for researchers to collect more compelling evidence to answer the question: “Does constraint-led training assist with the development of technical skills within interceptive sport?”’. While we endorse their call for more empirical evidence on the effectiveness of a CLA to practice and training design, we qualify it by highlighting some limitations of Clark, McEwan and Christie's systematic review

Interpersonal dynamics in baseline rallies in tennis

In tennis, the relative positioning of players on court constrains their opportunities to perform successful actions. In this study we proposed and validated an empirical function that captures the spatial-temporal relationship between tennis players during competitive performance. This parameter, termed goal-directed displacement index (GDD Index), is defined over time by the product of both players' distances to the central line of the court and to the centre of the net. Results showed that the GDD index successfully described tennis players' patterns of interaction, as well as identified breaks in patterns of play during competitive performance, due to changes in relative positioning on court. Our analysis revealed two different patterns of interpersonal interactions, cross and down-the-line rallies, and two ways for a break to emerge in game dynamics, parallel variation (transition from a cross court rally to a down-the-line rally) and angle opening (lateral displacement). Data suggest that the elaboration of specific individual profiles of performance for different players, using the GDD index, could improve performance analysis in tennis

A quantitative driver model of pre-crash brake onset and control

An existing modelling framework is leveraged to create a driver braking model for use in simulations of critical longitudinal scenarios with a slower or braking lead vehicle. The model applies intermittent brake adjustments to minimize accumulated looming prediction error. It is here applied to the simulation of a set of lead vehicle scenarios. The imulation results in terms of brake initiation timing and brake jerk are demonstrated to capture well the specific types of kinematics-ependencies that have been recently reported from naturalistic near-crashes and crashes

How do treadmill speed and terrain visibility influence neuromuscular control of guinea fowl locomotion?

Locomotor control mechanisms must flexibly adapt to both anticipated and unexpected terrain changes to maintain movement and avoid a fall. Recent studies revealed that ground birds alter movement in advance of overground obstacles, but not treadmill obstacles, suggesting context-dependent shifts in the use of anticipatory control. We hypothesized that differences between overground and treadmill obstacle negotiation relate to differences in visual sensory information, which influence the ability to execute anticipatory manoeuvres. We explored two possible explanations: (1) previous treadmill obstacles may have been visually imperceptible, as they were low contrast to the tread, and (2) treadmill obstacles are visible for a shorter time compared with runway obstacles, limiting time available for visuomotor adjustments. To investigate these factors, we measured electromyographic activity in eight hindlimb muscles of the guinea fowl (Numida meleagris, N=6) during treadmill locomotion at two speeds (0.7 and 1.3 m s−1) and three terrain conditions at each speed: (i) level, (ii) repeated 5 cm low-contrast obstacles (90% contrast, black/white). We hypothesized that anticipatory changes in muscle activity would be higher for (1) high-contrast obstacles and (2) the slower treadmill speed, when obstacle viewing time is longer. We found that treadmill speed significantly influenced obstacle negotiation strategy, but obstacle contrast did not. At the slower speed, we observed earlier and larger anticipatory increases in muscle activity and shifts in kinematic timing. We discuss possible visuomotor explanations for the observed context-dependent use of anticipatory strategies

Sujets et savoirs en mouvement. Variations sur le ‹Roman de la Rose› dans la littérature allégorique italienne à la fin du XIIIe siècle (‹Il Fiore›/‹L’Intelligenza›)

Der Beitrag untersucht zwei Beispiele für die frühe Rezeption des ›Roman de la Rose‹ in Italien. In ›Il Fiore‹ (um 1285/1295) werden die zentralen Handlungssequenzen des französischen Vorbilds in 232 Sonetten wiedergegeben. Mit ihren Lücken und Sprüngen untergräbt die lyrische Form jegliche narrative Kohärenz und Kohäsion; wie bei Guillaume de Lorris und Jean de Meun wird auf diese Weise ein instabiles, dynamisches ›Ich‹ in Szene gesetzt. In ›L’Intelligenza‹ (um 1300) erscheint der Erzähler-Sprecher von Anfang an durchlässig – ein mobiler Standpunkt, der von der Vielfalt der Welt durchquert wird und deshalb fast gänzlich verschwindet. In allen drei Texten lässt sich subjektives Wissen nicht in einem einheitlich gestalteten, linear organisierten Schema abbilden. Weil es sich durch seine Bindung an ein ›Ich‹ permanent neu konfiguriert, bedarf dieses Wissen einer besonderen, gleichermaßen narrativen und nicht-narrativen Form, die offen, vielfältig und beweglich ist.This article examines two examples of the early reception of the Roman de la Rose in Italy. In Il Fiore (ca. 1285-1295), the core plot sequences from the earlier French text are echoed in 232 sonnets. With its omissions and leaps, the lyrical form undermines any kind of narrative coherence and cohesion; as in the work of Guillaume de Lorris and Jean de Meun, this creates an instable, dynamic “I.” In L’Intelligenza (ca. 1300), the narrator-speaker appears from the beginning to be permeable – a mobile point of view which is threaded through with the world’s diversity and thus disappears almost entirely. In all three texts, subjective knowledge cannot be depicted in the form of a uniformly shaped and linear diagram. Because it is continuously being reconfigured due to its connection to an “I,” this knowledge requires a special form which is simultaneously narrative and non-narrative, one which is open-ended, diverse, and flexible

Informational constraints on interceptive actions of elite football goalkeepers in 1 v1 dyads during competitive performance

The aim of this study was to examine whether perceptual variables can provide informational constraints for the goalkeepers to intercept the ball successfully in 1v1 dyads. Video images of 42 actions (1v1 in direct shots) were selected randomly from different matches and divided into conceded goals (n=20) and saved actions (n=22) to investigate interceptive actions of 20 goalkeepers in the English Premier League in season 2013-2014. Time to Contact (TTC) of the closing distance gap between shooter and goalkeeper was obtained by digitising actions in the 18-yard penalty box. Statistical analyses revealed that, in sequences of play resulting in an intercepted shot at goal, goalkeepers closed down outfield players in the X axis, whereas when a goal was conceded, there was a significantly delayed movement by goalkeepers toward the shooters in this plane. The results of canonical correlations showed that a decreasing distance between a shooter and goalkeeper, and accompanied reduction in relative interpersonal velocity followed a temporal pattern. Findings of this study showed how perception of key informational constraints on dyadic system relations, such as TTC, interpersonal distance and relative velocity, constrain elite goalkeepers' interceptive actions, playing an important role in successful performance