SKILLED RIDERS MANAGE HORSE GAIT COMPLEXITY THROUGH A GAIT TRANSITION WHILST ALSO MAINTAINING STABLE HORSE-RIDER COORDINATION VARIABILITY

Equestrian riders aim to cue smooth transitions between horse gaits. This study aimed to investigate whether competitive horse rider (n=10) decrease horse gait regularity and increase horse-rider coordination variability in the region of a gait transition (n=6; both walk-trot, and trot-canter) relative to baseline walk, trot and canter. Resultant accelerations from IMUs affixed to the horse’s girth and rider’s pelvis were calculated. Horse gait regularity was quantified as multiscale sample entropy (MSSE) of the pelvis. Horse-rider coordination variability (Coordvar) was quantified as the standard deviation of the horse-rider continuous relative phase. Pre-transition MSSE did not increase; post-transition MSSE significantly decreased (paired t-tests; pvar were found. Therefore, horse gait or horse-rider Coordvar does not increase in a transition

LOWER LIMB JOINT COORDINATION STRATEGIES OF 5-7 AND 9-11-YEAR-OLD CHILDREN ON DOMESTIC TRAMPOLINES OF DIFFERENT STIFFNESSES

The aim of this research was to assess differences in lower limb coordination in two developing age groups during trampoline bouncing, and if alterations in trampoline stiffness influence coordination strategies in children. Eighteen participants were recruited and grouped based on age; 5-7 and 9-11 years old. Each participant performed twenty bounces on two different trampolines of high and low stiffness. Lower limb kinematics were recorded using 3D motion capture and analysed across ten middle bounces for each trampoline. Findings demonstrated that the two different age groups employed different coordination strategies, with some changes with different trampoline stiffnesses. This information could be useful for trampoline manufacturers to modify trampolines for age-specific trampoline use

LOWER LIMB KINEMATICS OF CHILDREN JUMPING ON DOMESTIC TRAMPOLINES

Domestic trampolines are a globally popular recreational activity for children, however this comes with a potentially increased risk of lower limb strains. The aim of this research was to determine if trampolines of differing stiffness influence lower limb kinematics in children. Fourteen participants grouped based on age; 5-7 and 9-11 years old, each performed twenty bounces on three different trampolines of varying stiffness. Lower limb kinematics were analysed across the ten middle bounces for each trampoline. Findings demonstrated no significant interaction effects across any hip, knee, ankle or foot kinematic variables across the trampolines within both age groups. There were also no significant differences in performance variables across the three trampolines. This study suggests that children do not appear to alter lower limb kinematics in adapting to different trampoline stiffness\u27s

APPLICATION OF SURFACE EMG DECOMPOSITION TO IDENTIFY CHANGES IN NEUROMUSCULAR CONTROL DURING FATIGUING EXERCISE

The purpose of this study was to apply surface EMG decomposition to identify changes in neuromuscular control of lower limb muscles during fatiguing exercise. Trained participants (n=15) completed a repeat sprints cycling fatigue protocol. Motor unit firing rates and motor unit recruitment timings were identified for six muscles. A moderate to strong correlation between firing rates and recruitment timings were identified for individual participant data (r = -0.46 to r = -1.00). No significant group effects were reported when each muscle was examined independently (repeat measures ANOVA; slope, intercept; F \u3c 1.84, p \u3e 0.119). However, changes in regression parameters were indentified for individual participant data. Surface EMG decomposition provides a novel approach for identifying individual changes in neuromuscular control of lower limb muscles during fatiguing exercise

UPPER LIMB JOINT COORDINATION DURING ROUND-OFF IN FEMALE GYMNASTICS

The aims of this study were to integrate the analysis of the elbow joint loading kinetics with the coordination and coordination variability across three round-off (RO) techniques (‘Parallel’, ‘Reverse’, ‘T-shape’). Twelve young female gymnasts performed 6 RO trials in each technique. Kinematic and kinetic data were collected for each trial. Statistical parametric mapping of mean elbow joint ad/abduction moments was performed to compare differences between techniques. Modified vector coding technique were used to asses coordination patterns and coordination variability (CAV). Results indicated that the combination of anti-phase coordination and lower coordination variability using ‘Reverse’ technique may explain the mechanism which leads to increased elbow adduction moment and could result in overuse elbow injury

COORDINATION VARIABILITY ASSOCIATED WITH ATTENDENCE TO A LONGITUDINAL REDUCING BIOFEEDBACK SCHEDULE

The aim of this paper was to assess skill exploration via coordinated variability (CoordVar) during attendance to a longitudinal, reducing biofeedback (BFb) intervention. Novices (n=15 BFb; n=15 Control) were introduced to a lunge touch task. Visual BFb were given on the timing and magnitude of rear leg kinematics. A modified CI2 method (CI2area) was used to quantify CoordVar for rear leg joint couplings. Coefficient of variability was used to quantify CoM horizontal velocity as performance variability (PerfVar). Linear regression 95% confidence intervals were compared between groups to assess changes over time. The BFb group demonstrated increasing CoordVar as a response to the BFb, with all participants showing no change in PerfVar. This highlights the potential for CoordVar to identify the effectiveness of BFb provision by practitioners

Analysis of Whole-Body Coordination Patterning in Successful and Faulty Spikes Using Self-Organising-Map-Based Cluster Analyses: A Secondary Analysis

This study was designated to investigate the whole-body coordination patterning in successful and faulty spikes using Self-Organising-Map-Based Cluster Analyses. Ten young elite volleyball players (aged 15.5 ± 0.7 years) performed 60 volleyball spikes in real-game circumstances with two blocks. Adopting the cluster analysis based on a Self-Organising-Map, the whole body coordination patterning was explored between the successful and faulty spikes of individual players. The cluster analysis portrayed that the whole-body, upper-limbs and lower-limbs coordination patterning of each individual’s successful spikes were similar to his faulty spikes. The same condition was authenticated for the ROMs patterning. Nevertheless, the upper-limbs angular velocity patterning of the players’ successful/faulty spikes was similar. The SPM analysis also portrayed significant differences between the normalized upper-limbs angular velocities from 35% to 45% and from 76% to the end of the spike movement. Alt-hough the lower-limbs angular velocities are vital for achieving higher jumps in volleyball spike, the results of this study por-trayed that the upper-limbs angular velocities distinguish the differences between successful and faulty spikes among the attack-ers. This confirms the fact that volleyball coaches could shift their focus toward the upper-limbs’ strength and coordination training for higher success rates among the volleyball attackers

Reliability of electromyography during 2000 m rowing ergometry

Purpose. This study aimed to investigate the reliability of surface electromyography (EMG) assessed at seven muscles during three repeated 2000 m rowing ergometer sessions. Methods. Twelve male well-trained rowers participated in a repeated measures design, performing three 2000 m rowing ergometer sessions interspersed by 3–7 days (S1, S2, S3). Surface electrodes were attached to the gastrocnemius, biceps femoris, gluteus maximus, erector spinae, vastus medialis, rectus abdominis and latissimus dorsi for EMG analysis. Results. No differences existed between 2000 m sessions for EMG amplitude for any of the seven muscles (p = 0.146–0.979). Mean coefficient of variation of EMG for 6 of 7 muscles was ‘acceptable’ (12.3–18.6%), although classed as ‘weak’ for gastrocnemius (28.6%). Mean intra-class correlation coefficient values across muscles ranged from ‘moderate’ to ‘very large’ (0.31–0.89). Within-session EMG activation rates of vastus medialis were greater during 0–500 m and 1500–2000 m segments, compared with 500–1000 m and 1000–1500 m (p < 0.05). Values for biceps femoris and gluteus maximus were significantly higher during 1500–2000 m compared to 500–1000 m and 1000–1500 m (p < 0.05). The general pattern was for higher activation rates during 0–500 m and 1500–2000 m compared to 500–1000 m and 1000–1500 m. However, there were no between-sessions differences in EMG for any of the 500 m segments (p > 0.05). Conclusion. Reliability of EMG values over repeated 2000 m sessions was generally ‘acceptable’. However, EMG was seemingly not sensitive enough to detect potential changes in neural activation between-sessions, with respect to changes in pacing strategy

Experiencing Simulated Confrontations in Virtual Reality

The use of virtual reality (VR) to simulate confrontational human behaviour has significant potential for use in training, where the recreation of uncomfortable feelings may help users to prepare for challenging real-life situations. In this paper we present a user study (n=68) in which participants experienced simulated confrontational behaviour performed by a virtual character either in immersive VR, or on a 2D display. Participants reported a higher elevation in anxiety in VR, which correlated positively with a perceived sense of physical space. Character believability was influenced negatively by visual elements of the simulation, and positively by behavioural elements, which complements findings from previous work.We recommend the use of VR for simulations of confrontational behaviour, where a realistic emotional response is part of the intended experience. We also discuss incorporation of domain knowledge of human behaviours, and carefully crafted motion-captured sequences, to increase users’ sense of believability

Leg dominance effects on knee kinematics in unilateral and bilateral squats

Squatting movements are often used to assess known risk factors of injury such as knee valgus angle. This study aims to investigate the knee kinematics during unilateral and bilateral squats in relation to the dominant and non-dominant leg. Five uninjured participants completed three squats in three conditions; dominant unilateral, non-dominant unilateral and bilateral. Knee extension and valgus angles were calculated. Maximum knee valgus angle was higher in the non-dominant unilateral trial than the same leg during the bilateral squat (unilateral = 10.6?, bilateral = 8.4?; p < 0.05). Knee extension angles were significantly lower during bilateral squats (unilateral = 111.9? & 109.2?, bilateral = 97.5? & 98.2?; p < 0.05). Limb dominance effects knee valgus during squatting, and should therefore be taken into account during injury risk assessments