Jonathan Wheat

Developmental changes in the dynamical structure of postural sway during a precision fitting task.

Recent research using measures to assess the time-dependent structure of postural fluctuations has provided new insights into the stability and adaptability of human postural control in adults. To date, little research has examined how postural dynamics reflecting the stability and adaptability of postural control may change as a function of development, especially during supra-postural tasks. The goal of this study was to examine the dynamics of postural fluctuations during a manual-fitting task in which precision, visual and postural task constraints were altered in children and adults. Three age groups were tested: 7-, 10-year olds and college aged adults. Recurrence quantification analysis (RQA) was used to assess the regularity (percent determinism) and complexity (entropy) of the center of pressure (CoP) in the anterior–posterior (AP) and medial-lateral (ML) directions. The CoP patterns exhibited by adults were more deterministic and more complex (higher entropy) than those of the 7-year-old children under the different experimental manipulations. No differences between the adults and the 10-year-old children were observed. The increase in determinism with a corresponding increase in entropy exhibited by the adults and older-children during a manual fitting task may be a prospective mechanism over which postural movements follow a more predictable path allowing for stable and flexible task performance. Our results also support the notion that complex postural fluctuations (as measured by RQA entropy) are functional and typically increase as the precision requirements of a manual task increase.

Association Between Foot Type And Tibial Stress Injuries: A Systematic Review.

Objectives: To systematically review published articles investigating the association between structural foot characteristics and tibial stress injuries, and to suggest possible future avenues of research in this area. Methods: Literature was identified, selected and appraised in accordance with the methods of a systematic review. Articles potentially relevant to the research question were identified by searching the following electronic databases: Amed, Cinahl, Index to UK theses, Medline, PubMed, Scopus, Sports discus and Web of science. Duplicates were removed and, based on the title and abstract, the full text of relevant studies were retrieved. Two reviewers independently assessed papers; this formed the basis for the inclusion of the most appropriate trials. Results: From the 479 articles originally identified, nine were deemed appropriate for inclusion in the review. In general, specific data relating to this relationship was limited. Outcomes of the nine investigations were difficult to compare due to differing methods used across studies. Results have proved conflicting, with limited evidence found to implicate any specific foot type as a potential risk factor for tibial stress injuries. Conclusions: No definitive conclusions can be drawn relating foot structure or function to an increased risk of tibial stress injuries. Extremes of foot types are likely to pose an increased risk of tibial stress injuries compared to normal arched feet.

The measurement of upper body alignment during the golf drive

Abstract Transverse plane rotations of the upper body are often estimated during the golf swing. The aim of this study was to determine the agreement between upper body alignments measured using markers attached to the thorax and markers on the acromion process during the golf drive. Three-dimensional coordinate data from nine markers were collected (300 Hz) during eight golf drives for 10 participants. The transverse plane alignment of the upper body was calculated using three techniques: inter-acromion vector, thorax vector, and Cardan angles. Agreement between the methods was then assessed using intra-class correlation and 95% limits of agreement. Our results suggested that the thorax vector can be used to provide an accurate estimation of thorax alignment at all stages of the golf swing (R ≥ 0.97, systematic difference < 1.0°, random difference < 3.8°). The inter-acromion vector gave an accurate estimation of thorax alignment at address (R = 0.90, systematic difference = 0.0°, random difference = 4.3°) but it should not be used to estimate thorax alignment at the top of the backswing (R = 0.32, systematic difference = −16.0°, random difference = 8.7°) or impact (R = 0.90, systematic difference = −5.1°, random difference = 8.3°) during the golf drive.

Development and assessment of a Microsoft Kinect based system for imaging the breast in three dimensions

Three-dimensional surface imaging technologies have been used in the planning and evaluation of breast reconstructive and cosmetic surgery. The aim of this study was to develop a 3D surface imaging system based on the Microsoft Kinect and assess the accuracy and repeatability with which the system could image the breast. A system comprising two Kinects, calibrated to provide a complete 3D image of the mannequin was developed. Digital measurements of Euclidean and surface distances between landmarks showed acceptable agreement with manual measurements. The mean differences for Euclidean and surface distances were 1.9mm and 2.2mm, respectively. The system also demonstrated good intra- and inter-rater reliability (ICCs>0.999). The Kinect-based 3D surface imaging system offers a low-cost, readily accessible alternative to more expensive, commercially available systems, which have had limited clinical use.

The potential of the Microsoft Kinect in sports analysis and biomechanics

The objective of this study was to assess the suitability of the Microsoft Kinect depth camera as a tool in segment scanning, segment tracking and player tracking. A mannequin was scanned with the Kinect and a laser scanner. The geometries were truncated to create torso ‘segments’ and compared. Separate shoulder abduction ( − 100° to 50°) and flexion motions (0°–100°) were recorded by the Kinect (using free and commercial software) and a Motion Analysis Corporation (MAC) system. Segment angles were compared. A participants centre of mass (COM) was tracked over a 6 × 3 m floor area using the Kinect and a MAC system and compared. Mean errors with uncertainty of the mass, COM position and principal moments of inertia were − 1.9 ± 1.6%, 0.5 ± 0.4% and 3 ± 2.6%, respectively. The commercial software gave the highest accuracy, in which the maximum and root mean square errors (RMSEs) were 13.85° and 7.59° in abduction and 21.57° and 12.00° in flexion. RMSEs in X, Y and Z COM positions were 0.12, 0.14 and 0.08 m, respectively, although vertical position (Y) was subject to a large systematic bias of 405 mm. The Kinects low cost and depth camera are an advantage for sports biomechanics and motion analysis. Although segment tracking accuracy is low, the Kinect could potentially be used in coaching and education for all three application areas in this study.

Use of gait sandals for measuring rearfoot and shank motion during running

Gait sandals may be used as an alternative to shoes in gait analysis. However, their similarity to running shoes remains unclear. This study aimed to compare rearfoot and shank kinematics between barefoot, running shoes and gait sandal conditions during running. We hypothesised that gait sandals would more closely replicate the kinematics seen when wearing running shoes than when barefoot. Rearfoot and shank kinematics were measured in 14 male participants as they ran in three footwear conditions (barefoot, gait sandals and running shoes) at 3.5m/s. Both barefoot and gait sandals resulted in greater peak rearfoot eversion compared to running shoes. Gait sandals were similar to running shoes for all other variables. These findings suggest that gait sandals can be used in place of running shoes during gait analysis to study rearfoot and shank kinematics.

An Integrated Approach to the Biomechanics and Motor Control of Cricket Fast Bowling Techniques

To date, scientific investigations into the biomechanical aspects of cricket fast bowling techniques have predominantly focused on identifying the mechanical factors that may predispose fast bowlers to lower back injury with a relative paucity of research being conducted on the technical features that underpin proficient fast bowling performance. In this review paper, we critique the scientific literature examining fast bowling performance. We argue that, although many published investigations have provided some useful insights into the biomechanical factors that contribute to a high ball release speed and, to a lesser extent, bowling accuracy, this research has not made a substantive contribution to knowledge enhancement and has only had a very minor influence on coaching practice. To significantly enhance understanding of cricket fast bowling techniques and, therefore, have greater impact on practice, we recommend that future scientific research adopts an interdisciplinary focus, integrating biomechanical measurements with the analytical tools and concepts of dynamical systems motor control theory. The use of qualitative (topological) analysis techniques, in particular, promises to increase understanding of the coordinative movement patterns that define ‘technique’ in cricket fast bowling and potentially help distinguish between functional and dysfunctional aspects of technique for individual fast bowlers.

Physical, Psychological and Emotional Benefits of Green Physical Activity: An Ecological Dynamics Perspective

Increasing evidence supports the multiple benefits to physical, psychological and emotional wellbeing of green physical activity, a topic of increasing interest in the past decade. Research has revealed a synergistic benefit of green physical activity, which includes all aspects of exercise and physical activity in the presence of nature. Our theoretical analysis suggests there are three distinct levels of engagement in green physical activity, with each level reported to have a positive effect on human behaviours. However, the extent to which each level of green physical activity benefits health and wellbeing is assumed to differ, requiring confirmation in future research. This elucidation of understanding is needed because previous literature has tended to focus on recording empirical evidence rather than developing a sound theoretical framework to understand green physical activity effects. Here we propose an ecological dynamics rationale to explain how and why green physical activity might influence health and wellbeing of different population groups. This framework suggests a number of unexplored, interacting constraints related to types of environment and population groups, which shape reported levels of benefit of green physical activity. Further analysis is needed to clarify the explicit relationship between green physical activity and health and wellbeing, including levels of engagement, types of environmental constraints, levels of physical activity, adventure effects, skill effects and sampling of different populations.

Assessing the suitability of the Microsoft Kinect for calculating person specific body segment parameters

Many biomechanical and medical analyses rely on the availability of reliable body segment parameter estimates. Current techniques typically take many manual measurements of the human body, in conjunction with geometric models or regression equations. However, such techniques are often criticised. 3D scanning offers many advantages, but current systems are prohibitively complex and costly. The recent interest in natural user interaction (NUI) has led to the development of low cost (~£200) sensors capable of 3D body scanning, however, there has been little consideration of their validity. A scanning system comprising four Microsoft Kinect sensors (a typical NUI sensor) was used to scan twelve living male participants three times. Volume estimates from the system were compared to those from a geometric modelling technique. Results demonstrated high reliability (ICC>0.7, TEM<1 %) and presence of a systematic measurement offset (0.001m\(^{3}\)), suggesting the system would be well received by healthcare and sports communities.

Assessment of a Microsoft Kinect-based 3D scanning system for taking body segment girth measurements: a comparison to ISAK and ISO standards

ABSTRACT Use of anthropometric data to infer sporting performance is increasing in popularity, particularly within elite sport programmes. Measurement typically follows standards set by the International Society for the Advancement of Kinanthropometry (ISAK). However, such techniques are time consuming, which reduces their practicality. Schranz et al. recently suggested 3D body scanners could replace current measurement techniques; however, current systems are costly. Recent interest in natural user interaction has led to a range of low-cost depth cameras capable of producing 3D body scans, from which anthropometrics can be calculated. A scanning system comprising 4 depth cameras was used to scan 4 cylinders, representative of the body segments. Girth measurements were calculated from the 3D scans and compared to gold standard measurements. Requirements of a Level 1 ISAK practitioner were met in all 4 cylinders, and ISO standards for scan-derived girth measurements were met in the 2 larger cylinders only. A fixed measurement bias was identified that could be corrected with a simple offset factor. Further work is required to determine comparable performance across a wider range of measurements performed upon living participants. Nevertheless, findings of the study suggest such a system offers many advantages over current techniques, having a range of potential applications.