Author(s): STRAFFORD, B., DAVIDS, K., STONE, J.A., NORTH, J.S., Institution: SHEFFIELD HALLAM UNIVERSITY , Country: UNITED KINGDOM, Abstract-ID: 1169

INTRODUCTION:
The coupling of perception and action, which emerges as Traceurs explore their Parkour environment seeking opportunities for action (affordances), forms the fundamental basis of skilled behaviour in ecological dynamics, established and refined by developing an athletes effectivities (movement/action capabilities) (1). The aims of this study were: 1) Examine the effect of action-scaled and body-scaled affordances on wall height estimation in Parkour, and 2) Examine the effect of wall height on anticipated climbing ability in Parkour.
METHODS:
Fifteen experienced Traceurs (age:24.1±6.9years, body mass:75.5±9.6kg, experience:6.5± 5.1years; stature:178.1 ± 6.6cm) estimated the height of three walls (Small:100cm, Medium:190cm, Large:380cm). Participants estimated the wall heights from the position where they would initiate jumping. This estimation was intrinsic as it was related to how participants estimated the wall height relative to their selected start position and anticipated ability to climb (2), without being allowed to first explore the walls with their body (action-scaled affordances). Traceurs were then given time to explore the three walls before providing another estimation of wall height. This estimation was extrinsic as it was related to how participants estimated the wall height after exploring the walls with their body (body-scaled affordances). Paired sample t-tests examined differences in the perceived height of three walls between modes of object perception (intrinsic: action-scaled and extrinsic: body-scaled). The Friedman test examined interactions between wall height and the anticipated climbing ability. The alpha level was p ≤ 0.05, with effect sizes calculated.
RESULTS:
There were differences with large effects between intrinsic and extrinsic estimations of wall height for the small wall t(14) = 6.461, p<.001, d=1.668 and medium wall t(14) = 5.020, p<.001, d=1.296. Intrinsic estimations of wall height were greater than the actual height of small wall (147.80±18.58cm, Error:47.80cm) and medium wall (274.93±54.38cm, Error:84.93cm). Extrinsic estimations of wall height were greater than the actual height of the small wall (111±10.27cm, Error: 11cm), but lower than the actual height of the medium wall (173.40±36.73cm, Error:-16.60cm). There was a significant interaction with a moderate effect of wall height on anticipated ability χ2(2)=12.474, p=0.002, W=0.416. Anticipated ability was significantly greater for the small wall (4.87±0.35) compared to the large wall (3.27±1.53) (Z=2.803,pbonf=0.005).
CONCLUSION:
The practical applications are: 1) In practice landscapes, Traceurs should be afforded time to explore objects in the environment relative to their body, 2) Traceurs should appraise the risk of the wall or jump relative to their abilities, and 3) When designing practice Traceurs should manipulate the height of objects relative to their movement/action capabilities (effectivities). References:1) Strafford et al. EJSS, 2021, 2) Taylor et al. Perception, 2011