A review of contemporary techniques for measuring ergonomic wear comfort of protective and sport clothing

Protective and sport clothing is governed by protection requirements, performance, and comfort of the user. The comfort and impact performance of protective and sport clothing are typically subjectively measured, and this is a multifactorial and dynamic process. The aim of this review paper is to review the contemporary methodologies and approaches for measuring ergonomic wear comfort, including objective and subjective techniques. Special emphasis is given to the discussion of different methods, such as objective techniques, subjective techniques, and a combination of techniques, as well as a new biomechanical approach called modeling of skin. Literature indicates that there are four main techniques to measure wear comfort: subjective evaluation, objective measurements, a combination of subjective and objective techniques, and computer modeling of human–textile interaction. In objective measurement methods, the repeatability of results is excellent, and quantified results are obtained, but in some cases, such quantified results are quite different from the real perception of human comfort. Studies indicate that subjective analysis of comfort is less reliable than objective analysis because human subjects vary among themselves. Therefore, it can be concluded that a combination of objective and subjective measuring techniques could be the valid approach to model the comfort of textile materials

A study of use of mini-bladders in active compression as a treatment for venous disease and lymphoedema

Venous disease of human lower limbs can cause a range of disorders that have a significant impact on the quality of life of patients. The sheer prevalence of varicose veins and its associated costs of treating late complications, such as chronic ulcers, contribute to a higher burden on health care resources as well as affecting the quality of life of people in the western world. The established gold standard of treatment is the application of graduated compression, applied mostly by medical compression bandages (MCB) and graduated compression stockings (GCS). Both systems are passive treatment methods as the pressure is generated by the component of the tangential force created due to the fabric tension resulted by the fabric stretch, which fails to provide uniform pressure around the leg circumference. This thesis presents the fundamental research of design, development, and evaluation of an active compression system consisting of an array of silicone based inflatable mini-bladders, which can provide a better solution for the treatment of venous disease and also lymphoedema. The mini-bladders were designed with two elastomeric layers; however, the mini-bladder inflation was limited only to one layer when the mini-bladder was filled with air. The minibladders could apply a radial force on to the treated surface when inflated, and the pressure in mini-bladders could be determined by measuring the back pressure, thus providing the ability to inflate mini-bladders to a predefined pressure. An array of mini-bladder can be used to apply pressure over a large area with a pre-determined resolution in order to create a graduated pressure profile. The 3-D deformation profile of mini-bladders was analysed using Finite Element Modelling and the simulations showed a good agreement with the experimental results within the pressure region which of interest for the compression therapy. The pressure transmission characteristics of the mini-bladders were investigated, initially on hard surfaces and then extended to a biofidelic leg surrogate. The hexagonal shaped mini-bladders provided the best pressure transmission properties. As a higher packing density can be achieved with hexagonal shaped mini-bladders in a honeycomb structure, a prototype active compression device was designed with hexagonal shape mini-bladders. Moreover, the interface pressure generated by the mini-bladders demonstrated a good linear relationship with the mini-bladder inflation pressure, which could be used as a calibration curve for the mini-bladders to inflate the mini-bladders to apply a predefined pressure. The second phase of the experiments, were conducted with a biofidelic lower leg surrogate covered with artificial skin and fat layers of different Young's modulus values. To the best of the author's knowledge this type of validation was the first of its kind in compression therapy research. The research has proved that mini-bladders can be used to apply a uniform circumferential pressure irrespective of the position of the lower leg surrogate; which proves the validity of the research hypothesis. The pressure propagation through the fat layers were around 35%-45% of the mini-bladder inflation pressure. Moreover, the propagation of the pressure through the fat layers varied with the modulus of the fat layers; the fat layer having lowest modulus recorded the highest pressure transmission percentage. A prototype of an active compression system was designed with mini-bladder arrays integrated within a silicone layer, in which the mini-bladders were directly in-contact with the skin. The laboratory experiments demonstrated that the developed active compression system was capable of delivering the required graduated pressure profiles

Design and Testing of a Traction/Distraction Knee Brace

A new knee brace design is required to provide non-surgical distraction of the knee joint for extended periods of time. This knee brace needs to apply traction force to the joint directly, rather than indirectly unloading one compartment. In providing such a design, this research had two objectives: 1) to design a lower-leg knee brace that can apply traction load to the knee; and 2) to test prototypes of these lower-leg knee brace components and relate the traction load to wearer discomfort and interface force. The first objective was met through prospective analysis and iterative design. A planar finite element (FE) model of the lower leg was used to analyse the effect of knee brace coverage. It was observed that increasing the coverage of the knee brace may reduce interface pressures and concentrations of force. A lower-leg knee brace was designed responding to this model, using fibreglass casts with embedded fasteners to transfer load. Braces were manufactured in three lengths for testing: 3”, 7”, and a combined (“mixed”) design with components from each. Nine participants were recruited for pilot testing of the lower leg knee brace. A mechanical test frame was built to apply traction load to the participants’ legs through each of the prototype knee braces. The load in the test frame was increased in 3kgf increments as interface force measurements were taken. Participants self-reported their discomfort on an 11-point Likert scale or Numerical Rating Scale (NRS). Results of the pilot study showed significant differences among the brace designs. The 3” design showed higher NRS scores than the 7” and mixed designs by a full NRS step. Graphical profiles of the interface force suggested that this difference may be the result of higher interface forces distributed across the smaller area of the 3” brace. However, no significant correlation between maximum interface force and self-reported pain was found. Parameters characterizing the shape of the participant’s lower legs indicated that leg shape may influence brace effectiveness. This study concluded that a rigid knee brace is indeed a valid design, but a longer knee brace interface is required for the anterior surface of the leg to improve comfort. This length may not be required for the posterior surface. Further, this study demonstrated simple relationships among applied load, interface force, and wearer discomfort. Future work will adapt this design to the upper leg and optimize the design to minimize force concentrations at the joints

Evaluation of the Accuracy and Practicability of Predicting Compression Garment Pressure Using Virtual Fit Technology

In this study, we evaluated the feasibility of using the virtual fit pressure map in a clothing-specific CAD program to predict pressures applied by sports compression garments by analyzing pressure prediction accuracy and process practicability. In wearer trials with whole-body compression sportswear, we measured in vivo pressures and compared them to virtual pressures recorded from the virtual fit pressure maps of the garments fitted to 13 participants’ body scan avatars. No clear correlations between virtual and in vivo pressures were identified and problems in the virtual fit process became apparent. The CAD software currently lacks a link to physical fabric, seam and component properties, which inhibits its use for predictions in new product development. By considering all simulation settings and assessing the numerical pressure prediction capability of a clothing-specific CAD program, this research provides a step forward in assessing the limitations of virtual fit for technical product development

DEVELOPMENT OF SEAMED COMPRESSION SOCKS AND COMPARISON WITH CLASS I SOCKS USING EXISTING MATHEMATICAL MODELS

Compression therapy is an important method for treating venous diseases such as venous edema and venous hypertension. Regular compression therapy's main objective is to diminish leg swelling by controlling blood flow and avoiding the recurrence of reversible blood flow. Compression socks are often recommended as therapeutic garments. In this study, a seamed compression sock was developed using fabric with an interlock knit structure. Three other sock samples were produced by using circular knitting MERZ CC4 model machine for comparison. The results demonstrate that the developed sock meets all the requirements of compression class I. Statistical analysis reveals that fabric parameters, particularly fabric weight, effectively explain compression pressure intensity according to the values of coefficient of determination, coefficient of correlation (r), and means sum of square errors (MSE). In this work, Laplace's Law and a few preexisting mathematical models were used to calculate the compression pressure of both standard compression socks and socks with seams, with results that were essentially similar. The points of data are tightly clustered around line of regression, showing that there is little variation in the compression pressure for socks with seams

An investigation into pressure delivery by sport compression garments and their physiological comfort properties

Sport compression garments have gained popularity amongst fitness enthusiasts in recent years, whilst scientific knowledge on their performance in terms of pressure generation on the underlying limb and the physiological comfort of the wearer remains scarce. The aim of this research is to predict, measure and validate pressure generated by SCGs on the underlying tissue of human and to evaluate the physiological comfort performance of the garments. Medical compression garments, their application, classification and the methods used in the prediction and validation of theoretical pressure inserted by them, were investigated through background research. This knowledge is used as a base, in order to predict and validate the theoretical pressure induced by sport compression garments. The theoretical pressure was predicted using the Law of Laplace, by testing the fabrics comprising sport compression garments for tensile properties according to a suitable method which was developed for the application under investigation. Validation of theoretical pressure was carried out through a linear regression model, whereby measured interface pressure generated by fabric sleeves over rigid cylinders was predicted with high accuracy, having the theoretical pressure as the predictor. Furthermore, the influence of composition of different fabrics within one garment on tensile properties and the resultant pressure was evaluated. It was observed that the amount and power of each fabric within the composition dictates the resultant pressure. The influence of the combination of weft and warp strain on interface pressure was also investigated and it was observed that the introduction of warp strain increases the resultant interface pressure. The physiological comfort properties of fabrics comprising sport compression garments were examined with standard and developed methods of testing. The developed method consisted of the introduction of strain in the weft direction and/or moisture when testing the fabrics, with the aim of investigating the comfort properties of the fabrics in conditions close to the wear applications of these garments. The moisture management capacity of the fabrics investigated was rated as poor. The introduction of strain increased the thermal resistance and decreased water-vapour resistance, surface roughness and friction of fabrics, whereas the presence of moisture decreased the surface roughness and increased the friction. Protocol was developed for taking lower-body measurements, relative to the application under investigation. A group of participants was scanned with a 3D body-scanner and the lower-body measurements were evaluated for participants who fitted the same size category of sport compression garments. Variations in circumferential measurements were observed, which ultimately affects the induced pressure from compression garments. Position of important lower-body points such as calf, knee, mid-thigh and maximum thigh were calculated in regards to crotch height along the leg for both genders, and by comparison to existing anthropometric knowledge, differences in the body proportions of different ethnic groups was revealed

Compression under pressure: physiological and methodological factors influencing the effect of compression garments on running economy

Evidence for the effects of compression garments on sports performance and physiological responses to dynamic exercise remains equivocal. Contradictory findings within the sporting literature are confounded by methodological heterogeneity in terms of; intensity and modality of exercise, type of garment worn, and the interface pressure produced by the garment. The interface pressure applied by compression clothing is an important measure in evaluating the bio-physical impact of compression. Interface pressure values obtained in vivo with two portable pressure devices (PicoPress and Kikuhime) were compared against a reference standard (HOSY). The PicoPress satisfied the a priori thresholds for acceptable validity at the posterior and lateral orientation with calf stockings and tights, confirming its future use to assess interface pressure. A small, likely beneficial improvement in running economy was observed with correctly fitted (95%:5%:0%; η2 = 0.55) but not oversized compression tights, indicating that a certain level of interface pressure is required. Compression tights improved running economy only at higher relative exercise intensities (77.7 - 91.5% V̇O2max). The absence of any improvement at lower intensities (67.1 - 77.6 % V̇O2max) suggest that changes in running economy from compression are dependent on relative exercise intensity when V̇O2max (%) is used as an anchor of exercise intensity. Comparing measures from two portable, wireless near-infrared spectroscopy (NIRS) devices (PortaMon and MOXY) we found that the low-cost and light-weight MOXY device gave tissue oxygen saturation values at rest and during exercise that were physiologically credible and suitable for future research. Compression tights did affect ground contact time but not tissue oxygen saturation, cardiovascular or other kinematic parameters during running at intensities equivalent to long-distance race speed. Compression tights can produce small improvements in running economy, but effects are restricted to higher intensity exercise and appear dependent on garment interface pressure. It remains unlikely that this small positive effect on running economy, in very specific conditions, is enough to result in a meaningful impact on running performance