Roozbeh Naemi

Quantifying lumbar-pelvis coordination during gait using a modified vector coding technique

The complexity of human gait patterns has become a topic of major interest in motor control and biomechanics. Range of motion is still the preferred method to quantify movement impairment, however, within these traditional linear measures, the inter-segmental coordination and movement variability is normally ignored. A dynamical systems approach using vector coding and circular statistics provides non-linear techniques to quantify coordination and variability. This study provides comprehensive vector coding and circular statistics calculations. Additionally, pelvis-lumbar coordination and coordination variability data obtained from ten healthy young male participants during five walking trials using an optoelectronic system is provided. This novel data can form the baseline information for future studies in this area of research. Finally, a new illustration to present coordination and coordination variability information of gait kinematics, combining the output from the modified vector coding technique with traditional time-series segmental angle data is presented. This technique, when applied to single patients can be beneficial to assess the effect of an intervention on the patient-specific inter-segmental coordination pattern with implications to the clinical setting.

The effectiveness of footwear as an intervention to prevent or to reduce biomechanical risk factors associated with diabetic foot ulceration: A systematic review

AIM Footwear interventions are used within clinical practice in an effort to reduce ulcerations however the effectiveness of these interventions is unclear. The aim of this paper was to conduct a systematic review which examined the effectiveness of footwear as an intervention for prevention of diabetic foot ulcers or the reduction of biomechanical risk factors for ulceration and to discuss the quality and interpret the findings of research to date. METHODS The CINAHL, Medline and Cochrane Register of Controlled Trials databases were searched with 12 articles identified for review. RESULTS The majority of these studies were cross sectional and examined the effect of different footwear conditions on plantar pressure measurements. Factors which influenced study findings such as participant selection, measurement and analysis techniques, footwear design and compliance are discussed and recommendations for future studies are provided. CONCLUSIONS No research to date has examined the effectiveness of footwear in preventing ulceration. Conflicting findings are reported on the effective of footwear interventions to prevent reulceration. While the use of rocker sole footwear and custom orthoses in plantar pressure reduction are supported in cross sectional studies, longitudinal studies are required to confirm their benefit.

Repeatability of WalkinSense® in shoe pressure measurement system: A preliminary study

Plantar pressure measurements are regularly utilised while assessing patients with in-shoe systems allowing for discrete assessment. In the present study a new portable system capable of continuous monitoring of plantar pressure is assessed for its repeatability when compared to another commercially available and widely used system.

Comparison of modes of feedback on glide performance in swimming

Abstract The software product “GlideCoach” was recently developed to give quantitative and qualitative feedback on the glide performance of a swimmer (Naemi & Sanders, 2008). This study compared the effect of feedback on glide performance from GlideCoach with video and verbal feedback. Nineteen elite swimmers were randomly assigned to one of three groups: Group 1 and 2 included six swimmers and Group 3 included seven swimmers. All participants performed ten dives in each of five sessions. Each group received one of three forms of feedback (video, video and verbal, and GlideCoach and verbal) for four sessions. In the fifth, retest session, performed 4 weeks after the fourth session, all groups received GlideCoach and verbal feedback only. This enabled the analysis of GlideCoach and verbal feedback on performance of the groups that had not yet received this feedback and assessment of the retention ability for the group that had. Feedback resulted in all groups recording an improvement, as indicated by effect sizes, for average velocity, glide factor (related to resistive drag), and initial velocity (P < 0.05). The improvement following the GlideCoach and verbal feedback was greater than that of the two other feedback methods for all variables of interest (P < 0.05), with effect sizes ranging from 1.0 to 2.5, compared with values less than 0.6 for the other feedback methods. We conclude that GlideCoach feedback is effective in improving glide performance.

A method for subject-specific modelling and optimisation of the cushioning properties of insole materials used in diabetic footwear.

This study aims to develop a numerical method that can be used to investigate the cushioning properties of different insole materials on a subject-specific basis. Diabetic footwear and orthotic insoles play an important role for the reduction of plantar pressure in people with diabetes (type-2). Despite that, little information exists about their optimum cushioning properties. A new in-vivo measurement based computational procedure was developed which entails the generation of 2D subject-specific finite element models of the heel pad based on ultrasound indentation. These models are used to inverse engineer the material properties of the heel pad and simulate the contact between plantar soft tissue and a flat insole. After its validation this modelling procedure was utilised to investigate the importance of plantar soft tissue stiffness, thickness and loading for the correct selection of insole material. The results indicated that heel pad stiffness and thickness influence plantar pressure but not the optimum insole properties. On the other hand loading appears to significantly influence the optimum insole material properties. These results indicate that parameters that affect the loading of the plantar soft tissues such as body mass or a persons level of physical activity should be carefully considered during insole material selection.

A new coordination pattern classification to assess gait kinematics when utilising a modified vector coding technique.

A modified vector coding (VC) technique was used to quantify lumbar-pelvic coordination during gait. The outcome measure from the modified VC technique is known as the coupling angle (CA) which can be classified into one of four coordination patterns. This study introduces a new classification for this coordination pattern that expands on a current data analysis technique by introducing the terms in-phase with proximal dominancy, in-phase with distal dominancy, anti-phase with proximal dominancy and anti-phase with distal dominancy. This proposed coordination pattern classification can offer an interpretation of the CA that provides either in-phase or anti-phase coordination information, along with an understanding of the direction of segmental rotations and the segment that is the dominant mover at each point in time. Classifying the CA against the new defined coordination patterns and presenting this information in a traditional time-series format in this study has offered an insight into segmental range of motion. A new illustration is also presented which details the distribution of the CA within each of the coordination patterns and allows for the quantification of segmental dominancy. The proposed illustration technique can have important implications in demonstrating gait coordination data in an easily comprehensible fashion by clinicians and scientists alike.

The effects of sport-specific and minimalist footwear on the kinetics and kinematics of three netball-specific movements

Netball is associated with a high frequency of chronic injuries. There is currently a trend towards the utilisation of minimalist footwear in netball players in lieu of traditional netball trainers. The aim of the current investigation was to examine the influence of netball-specific and minimalist footwear on the kinetics and three-dimensional (3-D) kinematics of three sport specific movements. Twelve female netballers performed three movements, run, cut and vertical jump, whilst wearing a conventional netball trainer and also a minimalist trainer. 3-D kinematics of the lower extremities were measured using an eight-camera motion analysis system alongside kinetic information which was obtained using a force platform. Kinetic/3-D kinematic differences between movements wearing different footwear were examined using paired t-tests. The kinetic analysis revealed that impact parameters were significantly greater in the minimalist footwear in comparison to the netball shoe for all three movements. In addition peak ankle eversion was shown to be significantly greater in the minimalist footwear in the running movement condition. The current study therefore suggests that the utilisation of minimalist footwear for netball training/performance may place netballers at increased risk from chronic injuries based on which a continued utilisation of netball-specific footwear may be recommended.

A “Hydrokinematic” Method of Measuring the Glide Efficiency of a Human Swimmer

The aim of this study was to develop and test a method of quantifying the glide efficiency, defined as the ability of the body to maintain its velocity over time and to minimize deceleration through a rectilinear glide. The glide efficiency should be determined in a way that accounts for both the inertial and resistive characteristics of the gliding body as well as the instantaneous velocity. A displacement function (parametric curve) was obtained from the equation of motion of the body during a horizontal rectilinear glide. The values of the parameters in the displacement curve that provide the best fit to the displacement-time data of a body during a rectilinear horizontal glide represent the glide factor and the initial velocity of the particular glide interval. The glide factor is a measure of glide efficiency and indicates the ability of the body to minimize deceleration at each corresponding velocity. The glide efficiency depends on the hydrodynamic characteristic of the body, which is influenced by the bodys shape as well as by the bodys size. To distinguish the effects of size and shape on the glide efficiency, a size-related glide constant and a shape-related glide coefficient were determined as separate entities. The glide factor is the product of these two parameters. The goodness of fit statistics indicated that the representative displacement function found for each glide interval closely represents the real displacement data of a body in a rectilinear horizontal glide. The accuracy of the method was indicated by a relative standard error of calculation of less than 2.5%. Also the method was able to distinguish between subjects in their glide efficiency. It was found that the glide factor increased with decreasing velocity. The glide coefficient also increased with decreasing Reynolds number. The method is sufficiently accurate to distinguish between individual swimmers in terms of their glide efficiency. The separation of glide factor to a size-related glide constant and a shape-related glide coefficient enabled the effect of size and shape to be quantified.

Multi-segment kinematic model to assess three-dimensional movement of the spine and back during gait

Background: Relatively little is known about spine during gait compared to movement analysis of the lower extremities. The trunk is often regarded and analysed as a single rigid segment and there is a paucity of information on inter-segmental movement within the spine and its relationship to pelvis and lower limbs. Objectives: To develop and validate a new multi-segment kinematic model to assess regional three-dimensional movement of the lumbar, lower thoracic and upper thoracic spine during gait. Study design: Observational study. Methods: The study was conducted in two parts: (1) to provide validation measures on the kinematic model built in commercially available software and (2) to apply the marker configuration to the spine at T3, T8 and L3 during gait analysis on 10 healthy male volunteers. Results: Proposed model revealed excellent concurrent validation measures between an applied input angle to the recorded output angle from the kinematic model. A high reliability was observed during gait analysis, both during a single session and between sessions for all participants. Conclusion: The thoracic region of the spine should not be modelled as a single rigid segment and the proposed three-dimensional cluster is reliable and repeatable to assess the inter-segmental movement of the spine. Clinical relevance Reliable kinematic data can be collected using the three-dimensional cluster technique, thus, allowing researchers to accurately distinguish between movement patterns of healthy individuals to those with a clinical condition, and provide confidence in data acquisition during the monitoring process of an implemented rehabilitation intervention programme.

The Effectiveness of Footwear and Other Removable Off-loading Devices in the Treatment of Diabetic Foot Ulcers: A Systematic Review

AIM To conduct a systematic review which examined the effectiveness of footwear and other removable off-loading devices as interventions for the treatment of diabetic foot ulcers or the alteration of biomechanical factors associated with ulcer healing and to discuss the quality and interpret the findings of research to date. METHODS The CINAHL, Medline and Cochrane Register of Controlled Trials databases were searched with seventeen articles identified for review. RESULTS Majority of the identified studies were randomised control trials which compared the ulcer healing rates of different footwear and other removable off-loading device interventions. Three categories of interventions were identified; 1) removable cast walkers (RCWs), 2) half or heel relief shoes and 3) therapeutic shoes. Most studies compared at least one intervention to a total contact cast (TCC). Factors which influenced study findings such as TCC application method, compliance, activity levels, and the footwear worn on the contralateral limb are discussed with recommendations provided for future studies. CONCLUSION Due to the lack of randomised controlled studies conducted in this area it is not currently possible to make strong conclusions on the interventions effectiveness. However, it appears the currently available therapeutic shoes were the least effective intervention followed by half or heel relief shoes. RCWs were found to be the most effective of the removable devices.