LIMIT CYCLE REPRESENTATION OF THE GYMNASTICS LONGSWING

Human movement science is searching for ways to capture global dynamics of our complex multi-segment system. The aim of this study was to explore differences in a limit cycle representation of longswings on high bar as a function of skill level. One elite international, one collegiate, and one novice gymnast performed four consecutive longswings on high bar. Through the novel representation of the longswing as a limit cycle, and exploration of the limit cycle characteristics, it is shown that higher frequency, more phase coherent oscillations, and lower limit cycle variability occurs as a function of skill level. It is suggested that this candidate collective variable be explored as a global indicator of skill level and learning that can provide insight into the efficiency of the mechanical system

Force trace characteristics in anterior cruciate ligament deficient and uninjured knees during a maximal isometric task

Anterior cruciate ligament (ACL) deficiency has been shown to alter the muscle function of the leg. This study aimed to investigate differences in force trace characteristics of a maximal isometric task between ACL deficient and uninjured knees. Six ACL injured and uninjured participants completed maximal adduction, extension, and flexion isometric contractions. Peak, mean, standard deviation (SD), coefficient of variance (CV), frequency and signal regularity were calculated for all trials. Mean flexion force was larger in the ACL intact (0.91 N/kg) compared to their deficient (0.67 N/kg; p<0.05) knee. SD, CV and frequency composition of the extension trial differed between limbs in the uninjured (p<0.05). Analysis of variability, frequency and regularity of a signal may provide information on the function of the knee

Coordination as a function of skill level in the gymnastics longswing

The purpose of this study was to investigate the nature of inter-joint coordination at different levels of skilled performance to: (1) distinguish learners who were successful versus unsuccessful in terms of their task performance; (2) investigate the pathways of change during the learning of a new coordination pattern and (3) examine how the learner’s coordination patterns relate to those of experts in the longswing gymnastics skill. Continuous relative phase of hip and shoulder joint motions was examined for longswings performed by two groups of novices, successful (n = 4) and unsuccessful (n = 4) over five practice sessions, and two expert gymnasts. Principal component analysis showed that during longswing positions where least continuous relative phase variability occurred for expert gymnasts, high variability distinguished the successful from the unsuccessful novice group. Continuous relative phase profiles of successful novices became more out-of-phase over practice and less similar to the closely in-phase coupling of the expert gymnasts. Collectively, the findings support the proposition that at the level in inter-joint coordination a technique emerges that facilitates successful performance but is not more like an expert’s movement coordination. This finding questions the appropriateness of inferring development towards a “gold champion” movement coordination

Force trace characteristics in anterior cruciate ligament deficient and uninjured knees during a maximal isometric task

Anterior cruciate ligament (ACL) deficiency has been shown to alter the muscle function of the leg. This study aimed to investigate differences in force trace characteristics of a maximal isometric task between ACL deficient and uninjured knees. Six ACL injured and uninjured participants completed maximal adduction, extension, and flexion isometric contractions. Peak, mean, standard deviation (SD), coefficient of variance (CV), frequency and signal regularity were calculated for all trials. Mean flexion force was larger in the ACL intact (0.91 N/kg) compared to their deficient (0.67 N/kg; p<0.05) knee. SD, CV and frequency composition of the extension trial differed between limbs in the uninjured (p<0.05). Analysis of variability, frequency and regularity of a signal may provide information on the function of the knee