Can coordination variability identify performance factors and skill level in competitive sport? The case of race walking

Abstract

Background: Marginal changes in the execution of competitive sports movements can represent a significant change for performance success. However, such differences may emerge only at certain execution intensities and are not easily detectable through conventional biomechanical techniques. This study aimed to investigate if and how competition standard and progression speed affect race walking kinematics from both a conventional and a coordination variability perspective.

Methods: Fifteen experienced athletes divided into three groups (elite, international, and national) were studied while race walking on a treadmill at two different speeds (12.0 and 15.5 km/h). Basic gait parameters, the angular displacement of the pelvis and lower limbs, and the variability in continuous relative phase between six different joint couplings were analyzed.

Results: Most of the spatio-temporal, kinematic, and coordination variability measures proved sensitive to the change in speed. Conversely, non-linear dynamics measures highlighted differences between athletes of different competition standard when conventional analytical tools were not able to discriminate between different skill levels. Continuous relative phase variability was higher for national level athletes than international and elite in two couplings (pelvis obliquity-hip flex/extension and pelvis rotation-ankle dorsi/plantarflexion) and gait phases (early stance for the first coupling, propulsive phase for the second) that are deemed fundamental for correct technique and performance.

Conclusion: Measures of coordination variability showed to be a more sensitive tool for the fine detection of skill-dependent factors in competitive race walking, and showed good potential for being integrated in the assessment and monitoring of sports motor abilities.

Keywords: Biomechanics; Gait; Joint coupling; Motor control; Sports technique; Training.

Fig. 1

Frontal plane views of the biomechanical model used for the analysis, where marker positions have been highlighted through white circles.

Fig. 2

Example of CRP calculation. The normalized phase plots (angular velocity vs. angular displacement) of elements 1 (A) and 2 (B) are used to calculate phase angles (C and D). Phase angles are then subtracted to calculate continuous relative phase of the 1 vs. 2 coupling. Coordination variability (deviation phase) is the standard deviation of CRP curves (E). HS = heel strike; V = vertical upright position; TO = toe-off; CRP = continuous relative phase.

Fig. 3

Average (mean ± SD) curves for the hip (A) and ankle (B) sagittal angles in the slow (12.0 km/h) and fast (15.5 km/h) pace conditions. Time is normalized to the gait cycle and expressed in percentage. Solid lines for elite; dash-dot lines for international; dashed lines for national.

Fig. 4

Coordination variability (mean ± SD) over the whole gait cycle and the subsequent functional phase (left to right columns). ^#Significant main effect between race walking speeds (p < 0.05); ^†Significant main effect between competition standards (p < 0.05). Outcomes of ANOVA and post hoc tests are reported below each subplot. White bars refer to 12.0 km/h, black to 15.5 km/h speed. HS = heel strike; VUP = vertical upright position; TO = toe-off; hp = hip; ak = ankle; po = pelvic obliquity; pr = pelvic rotation; E = elite level; I = international level; N = national level.

Fig. 5

Average (mean ± SD) continuous relative phase variability (deviation phase, DP) for the pelvis obliquity–hip flex/extension coupling in the slow (12.0 km/h) and fast (15.5 km/h) pace conditions. Time is normalized to the gait cycle and expressed in percentage. Solid lines for elite; dash-dot lines for International; dashed lines for national. Vertical upright position (VUP) and toe-off (TO) events are shown as an approximate average across the three groups for clarity of representation.