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Compression and texture in socks enhance football kicking performance

Hasan H, Davids K, Chow JY, Kerr G

Hum Mov Sci, 2016 Aug;48:102-11.
PMID: 27155962 DOI: 10.1016/j.humov.2016.04.008

The purpose of this study was to observe effects of wearing textured insoles and clinical compression socks on organisation of lower limb interceptive actions in developing athletes of different skill levels in association football. Six advanced learners and six completely novice football players (15.4±0.9years) performed 20 instep kicks with maximum velocity, in four randomly organised insoles and socks conditions, (a) Smooth Socks with Smooth Insoles (SSSI); (b) Smooth Socks with Textured Insoles (SSTI); (c) Compression Socks with Smooth Insoles (CSSI) and (d), Compression Socks with Textured Insoles (CSTI). Reflective markers were placed on key anatomical locations and the ball to facilitate three-dimensional (3D) movement recording and analysis. Data on 3D kinematic variables and initial ball velocity were analysed using one-way mixed model ANOVAs. Results revealed that wearing textured and compression materials enhanced performance in key variables, such as the maximum velocity of the instep kick and increased initial ball velocity, among advanced learners compared to the use of non-textured and compression materials. Adding texture to football boot insoles appeared to interact with compression materials to improve kicking performance, captured by these important measures. This improvement in kicking performance is likely to have occurred through enhanced somatosensory system feedback utilised for foot placement and movement organisation of the lower limbs. Data suggested that advanced learners were better at harnessing the augmented feedback information from compression and texture to regulate emerging movement patterns compared to novices.
The influence of ball-swing on the timing and coordination of a natural interceptive task

Sarpeshkar V, Mann DL, Spratford W, Abernethy B

Hum Mov Sci, 2017 Aug;54:82-100.
PMID: 28410536 DOI: 10.1016/j.humov.2017.04.003

Successful interception relies on the use of perceptual information to accurately guide an efficient movement strategy that allows performers to be placed at the right place at the right time. Although previous studies have highlighted the differences in the timing and coordination of movement that underpin interceptive expertise, very little is known about how these movement patterns are adapted when intercepting targets that follow a curvilinear flight-path. The aim of this study was to examine how curvilinear ball-trajectories influence movement patterns when intercepting a fast-moving target. Movement timing and coordination was examined when four groups of cricket batters, who differed in their skill level and/or age, hit targets that followed straight or curvilinear flight-paths. The results revealed that when compared to hitting straight trials, (i) mixing straight with curvilinear trials altered movement coordination and when the ball was hit, (ii) curvilinear trajectories reduced interceptive performance and significantly delayed the timing of all kinematic moments, but there were (iii) larger decrease in performance when the ball swung away from (rather than in towards) the performer. Movement coordination differed between skill but not age groups, suggesting that skill-appropriate movement patterns that are apparent in adults may have fully emerged by late adolescence.
Maximum isokinetic familiarization of the knee: Implication on bilateral assessment

Chan JPY, Krisnan L, Yusof A, Selvanayagam VS

Hum Mov Sci, 2020 Jun;71:102629.
PMID: 32452445 DOI: 10.1016/j.humov.2020.102629

PURPOSE: Familiarization is necessary for an accurate strength assessment as it reduces confounding factors such as learning and training effects. However, the number of contractions required for familiarization and whether cross-limb transfer during familiarization could affect bilateral assessment are unknown. This study aimed at identifying the number of maximum contractions required for isokinetic knee extension and flexion familiarization in both dominant (D) and non-dominant limb (ND).
METHODS: Twenty-eight right-limb dominant males (age: 22.64 ± 2.60 years, BMI: 23.82 ± 2.85 kg/m2) performed a total of 6 sets (each consisted of 5 continuous maximum contractions) at 60o/s for each limb.
RESULTS: The number of sets required for familiarization is determined when the average peak torque achieved stabilization from the series of contractions of each limb. For knee extension, 3 sets (15 contractions) were required for familiarization, whereas 2 sets (10 contractions) for knee flexion in both limbs. Interestingly, for knee extension in ND, the number of sets required for familiarization was reduced to 2 following contralateral contractions in D, however, for knee extension in D, there was no difference in the number of sets required for familiarization following contralateral contractions in ND. While for knee flexion, no cross-limb transfer was observed. These observations suggest the presence of cross-limb transfer from D to ND during familiarization which implies the involvement of the central nervous system.
CONCLUSIONS: Practically, familiarization for bilateral isokinetic strength assessment for knee extension and flexion at 60o/s should begin with the dominant limb for 3 sets to obtain accurate and reliable measurements.
The identification of high potential archers based on fitness and motor ability variables: A Support Vector Machine approach

Taha Z, Musa RM, P P Abdul Majeed A, Alim MM, Abdullah MR

Hum Mov Sci, 2018 Feb;57:184-193.
PMID: 29248809 DOI: 10.1016/j.humov.2017.12.008

Support Vector Machine (SVM) has been shown to be an effective learning algorithm for classification and prediction. However, the application of SVM for prediction and classification in specific sport has rarely been used to quantify/discriminate low and high-performance athletes. The present study classified and predicted high and low-potential archers from a set of fitness and motor ability variables trained on different SVMs kernel algorithms. 50 youth archers with the mean age and standard deviation of 17.0 ± 0.6 years drawn from various archery programmes completed a six arrows shooting score test. Standard fitness and ability measurements namely hand grip, vertical jump, standing broad jump, static balance, upper muscle strength and the core muscle strength were also recorded. Hierarchical agglomerative cluster analysis (HACA) was used to cluster the archers based on the performance variables tested. SVM models with linear, quadratic, cubic, fine RBF, medium RBF, as well as the coarse RBF kernel functions, were trained based on the measured performance variables. The HACA clustered the archers into high-potential archers (HPA) and low-potential archers (LPA), respectively. The linear, quadratic, cubic, as well as the medium RBF kernel functions models, demonstrated reasonably excellent classification accuracy of 97.5% and 2.5% error rate for the prediction of the HPA and the LPA. The findings of this investigation can be valuable to coaches and sports managers to recognise high potential athletes from a combination of the selected few measured fitness and motor ability performance variables examined which would consequently save cost, time and effort during talent identification programme.
Towards a Grand Unified Theory of sports performance

Glazier PS

Hum Mov Sci, 2017 Dec;56(Pt A):139-156.
PMID: 26725372 DOI: 10.1016/j.humov.2015.08.001

Sports performance is generally considered to be governed by a range of interacting physiological, biomechanical, and psychological variables, amongst others. Despite sports performance being multi-factorial, however, the majority of performance-oriented sports science research has predominantly been monodisciplinary in nature, presumably due, at least in part, to the lack of a unifying theoretical framework required to integrate the various subdisciplines of sports science. In this target article, I propose a Grand Unified Theory (GUT) of sports performance-and, by elaboration, sports science-based around the constraints framework introduced originally by Newell (1986). A central tenet of this GUT is that, at both the intra- and inter-individual levels of analysis, patterns of coordination and control, which directly determine the performance outcome, emerge from the confluence of interacting organismic, environmental, and task constraints via the formation and self-organisation of coordinative structures. It is suggested that this GUT could be used to: foster interdisciplinary research collaborations; break down the silos that have developed in sports science and restore greater disciplinary balance to the field; promote a more holistic understanding of sports performance across all levels of analysis; increase explanatory power of applied research work; provide stronger rationale for data collection and variable selection; and direct the development of integrated performance monitoring technologies. This GUT could also provide a scientifically rigorous basis for integrating the subdisciplines of sports science in applied sports science support programmes adopted by high-performance agencies and national governing bodies for various individual and team sports.
Expert - Non-expert differences in visual behaviour during alpine slalom skiing

Decroix M, Wazir MRWN, Zeuwts L, Deconinck FFJA, Lenoir M, Vansteenkiste P

Hum Mov Sci, 2017 Oct;55:229-239.
PMID: 28846855 DOI: 10.1016/j.humov.2017.08.012

The aim of this study was to investigate visual behaviour of expert and non-expert ski athletes during an alpine slalom. Fourteen non-experts and five expert slalom skiers completed an alpine slalom course in an indoor ski slope while wearing a head-mounted eye tracking device. Experts completed the slalom clearly faster than non-experts, but no significant difference was found in timing and position of the turn initiation. Although both groups already looked at future obstacles approximately 0,5s before passing the upcoming pole, the higher speed of experts implied that they shifted gaze spatially earlier in the bend than non-experts. Furthermore, experts focussed more on the second next pole while non-expert slalom skiers looked more to the snow surface immediately in front of their body. No difference was found in the fixation frequency, average fixation duration, and quiet eye duration between both groups. These results suggest that experts focus on the timing of their actions while non-experts still need to pay attention to the execution of these actions. These results also might suggest that ski trainers should instruct non-experts and experts to focus on the next pole and, shift their gaze to the second next pole shortly before reaching it. Based on the current study it seems unadvisable to instruct slalom skiers to look several poles ahead during the actual slalom. However, future research should test if these results still hold on a real outdoor slope, including multiple vertical gates.
Towards a Grand Unified Theory of sports performance: A response to the commentaries

Glazier PS

Hum Mov Sci, 2017 12;56(Pt A):184-189.
PMID: 28511799 DOI: 10.1016/j.humov.2017.04.016