Sports Bra Pressure: Effect on Core Body Temperature and Comfort Sensation

Background: Sports bras are engineer designed to enhance sports performance, which means that they need to provide an excellent fit, and offer adequate support and protection of the breasts to optimize their functionality. To effectively reduce breast motion during different intensity levels of exercise, the materials of sports bras are generally rigid which exert compressive forces onto the soft tissues of the breasts. However, these materials may still restrict air flow and inhibit body heat loss, while the pressure from the bra exerted onto the skin may also increases physiological strain and wear discomfort. This excessively high exerted pressure is known to produce an inhibitory effect on the sweating rate and associated with a significant rise in the axillary and core temperatures. This preliminary study therefore investigates the influence of bra pressure on the upper body temperature and thermal comfort following a short duration of treadmill running. Objective: The purpose of this study is to investigate the effect of increased bra pressure on thermal response following exercise. The findings provide bra designers with insight into bra pressure and related bra design features necessary for optimal wear comfort during physical activities. Methods: A total of 12 young women have participated in this study to don a changeable sports bra that allows adjustment of tension or replacement of the bra components. The skin and body core temperatures as well as heart rate for four bra conditions during treadmill running for 15 minutes at 8 km/h are recorded by using temperature and heart rate sensors. The subjectively perceived thermal and pressure comfort are evaluated by using a visual analog scale with ratings of 1 to 10.Results: Following exercise, there is no change in core temperature for all of the bra conditions studied. Even though the body core temperature may increase due to the higher rate of heat production with muscular work done during treadmill running, the increase in heat dissipation tends to balance the increase in rate of metabolic heat production to maintain a stable core temperature. After a short duration of treadmill running, the change in skin temperature ranges from 0.22oC to 3.56oC amongst the 4 bra conditions. The shoulder strap area shows a slight change in skin temperature during exercise, and the participants are particularly sensitive to the increased pressure in this area, thus adversely affecting their ratings of the thermal and pressure comfort. Conclusion: In this study, the increased bra pressure does not show significant change in core temperature and heart rate during short duration exercise. Even though the results are not statistically significant, the shoulder strap pressure is found to be related to the changes in skin temperature and subjective ratings of thermal and pressure comfort.

Effect of Contacting Surface on the Performance of Thin-Film Force and Pressure Sensors

Flexible force and pressure sensors are important for assessing the wear comfort of tightly fitting apparel. Their accuracy and repeatability depend on the sensor itself and the contacting surface. Measurements of the contact pressure on soft surfaces like human skin tend to be erroneous, which could be due to incorrect sensor calibrations. This study aims to examine the effects of human body parameters such as the hardness and temperature of the contacting surface by using a custom-made calibration setup and investigating the incorporation of rigid discs on the sensor surface. Two commercial force sensors, FlexiForce and SingleTact, and one pressure sensor, Pliance X, are used in the investigation. The findings reveal that adding rigid discs on both sides of the force sensors improves their sensitivity. Systematic calibration has been performed on the surfaces with different temperatures and hardness. The results show that FlexiForce and Pliance X tend to be affected by the changes in surface temperature and surface hardness. Prolonged testing time shows that the time dependence of SingleTact and Pliance X sensor is lower, which suggests that they are more suitable for lengthier evaluations in which interface pressure is exerted on the human body. In brief, sensor attachment and proper calibration should be thoroughly considered before using sensors for applications on soft surfaces, like the human body.

Case study on the effects of fit and material of sports gloves on hand performance

Active and sports fashion in the high-end market focuses on fit, superior comfort and functional performance for various end-uses. However, the engineering design of sports gloves in relation to hand anthropometry measurements remains unclear. In this study, two types of ready-to-wear sport gloves, namely, war-gaming glove and hiking glove were purchased from the market. The glove dimensions, fabrication properties and the effect of glove fit on hand and finger dexterity were investigated. Thirty female individuals (20-29 years old) participated a series of hand performance tests and subjective perception rating assessments towards the gloves. Results indicated that the active range of motion of fingers, finger tactile sensitivity, gripping strength and ability to handle pegs and marbles decreased with the use of gloves compared with bare hands. The perceptions of comfort and ease of hand motions decreased with the increased of wear time. The glove fit in terms of finger length dimensions was significantly correlated with hand grip force. The glove fit in hand, wrist and finger circumference dimensions had significant impact on the ability to handle small objects. It is suggested that hand length, hand circumference, finger circumference and the ratio of finger length to palm length should be considered in the design and development of gloves to improve hand performance and comfort.

Effects of indoor slippers on plantar pressure and lower limb EMG activity in older women

Open-toe mule slippers are popular footwear worn at home especially by older women. However, their biomechanical effects are still poorly understood. The objective of this study is to therefore evaluate the physical properties of two typical types of open-toe mule slippers and the changes in plantar pressure and lower limb muscle activity of older women when wearing these slippers. Five walking trials have been carried out by ten healthy women. The results indicate that compared to barefoot, wearing slippers results in significant increases in the contact area of the mid-foot regions which lead to plantar pressure redistribution from metatarsal heads 2-3 and the lateral heel to the midfoot regions. However, there is no significant difference in the selected muscle activity across all conditions. The findings enhance our understanding of slipper features associated with changes in biomechanical measures thereby providing the basis of slipper designs for better foot protection and comfort.

Effects of custom-made textile insoles on plantar pressure distribution and lower limb EMG activity during turning

Background

Turning during locomotion involves considerable changes of the body’s center of mass and reduced stability, as well as lower limb kinematics and kinetics. However, many previous studies have been carried out to evaluate the effectiveness and applications of orthotic insoles as well as different types of orthotic materials in various clinical symptoms, which are focused primarily on straight line walking. Hence, the influence of custom-made insoles with the use of advanced three-dimensional spacer fabrics on biomechanics parameters in terms of plantar pressure distribution and lower limb electromyography during turning movement was studied.

Methods

Twelve subjects performed 180-degree turning at a speed 3.07-3.74 km/h for five successful trials under 3 insoles conditions: wearing traditional ethylene vinyl acetate insoles and two different spacer-fabricated insoles, with the plantar pressure and lower limb muscle activity collected simultaneously. Turning movement was broken down into 3 phases for analysis: Turning initiation, turn around and turn termination.

Results

There was a statistically significance difference in plantar pressure between the traditional insoles and the insoles made of a spacer fabric as the top layer (p < 0.05). Compared to the traditional insoles, insoles made of a spacer fabric reduced the peak pressure (>12 %) and pressure–time integral (>13 %) in toes, metatarsal head 1 and metatarsal heads 2–3 at turning initiation; (>15 %) and (>17 %) in medial midfoot and medial heel at turn around. Insoles with spacer fabrics on the top and middle layer reduced both pressure parameters (>18 %) in toes and MTH 1 at turn termination. In terms of muscle activities, insoles with two-layer spacer fabrics could lower maximum muscle activities of vastus lateralis (>16 %; p < 0.05) at turn around.

Conclusions

Insoles with different fabrications could offer various pressure offloading patterns across the plantar and muscle activity changes while turning. Insoles with a spacer fabric on the top tend to reduce plantar pressure loading at different regions during turn initiation and turn around phases, while two-layer spacer-fabricated insoles may contribute to reduced vastus lateralis muscle activation during turn around. More importantly, this study provides a new dimension in the potential use of the textile-fabricated insoles which may widen the range of insole materials selection in the design and development of insoles so as to enhance the effectiveness of orthotic treatment.

Numerical simulation of pressure therapy glove by using Finite Element Method

Pressure therapy garments apply pressure to suppress the growth and flatten hypertrophic scars caused by serious burns. The amount of pressure given by the pressure garments is critical to the treatment adherence and outcomes. In the present study, a biomechanical model for simulating the pressure magnitudes and distribution over hand dorsum given by a pressure glove was developed by using finite element method. In this model, the shape geometry of the hand, the mechanical properties of the glove and human body tissues were incorporated in the numerical stress analyses. The geometry of the hand was obtained by a 3D laser scanner. The material properties of two warp knitted fabrics were considered in the glove fabric model that developed from the glove production pattern with 10% size reduction in circumferential dimensions. The glove was regarded an isotropic elastic shell and the hand was assumed to be a homogeneous, isotropic and linearly elastic body. A glove wearing process was carried in the finite element analysis and the surface-to-surface contact pressure between hand and glove fabric was hence obtained. Through validation, the simulated contact pressure showed a good agreement with the experimental interface pressure measurement. The simulation model can be used to predict and visualise the pressure distribution exerted by a pressure therapy glove onto hand dorsum. It can provide information for optimising the material mechanical properties in pressure garment design and development, give a clue to understand the mechanisms of pressure action on hypertrophic scars and ultimately improve the medical functions of pressure garment.

The Effect of Pressure Glove Tightness on Forearm Muscle Activity and Psychophysical Responses

OBJECTIVE

The impact of pressure glove tightness on maximum grip force, muscle activity, and psychophysical responses is investigated to facilitate the prescription of a suitable reduction factor (RF) for pressure treatment.

BACKGROUND

The wearing of pressure therapy gloves is often considered to hinder hand performance and cause discomfort, resulting in unsatisfactory treatment adherence during burn rehabilitation.

METHOD

A wear trial was carried out with 10 participants for three custom-made pressure gloves that consist of different RFs-10%, 15% and 20%-as well as for the bare hand. The surface electromyography of three forearm muscles was measured during tasks that involve moving marbles, buttoning a shirt, and typing. The psychophysical responses were also recorded.

RESULTS

The use of pressure gloves results in a reduction in the maximum gripping force. Gloves with tighter pressure contribute to lower perceived comfort and ease of hand motion. Increased glove tightness (with RFs of 15% and 20%) decreases muscle activity as compared to the bare-hand condition when buttoning a shirt. In terms of typing, the forearm muscle activity increases with high glove pressure (RF of 20%).

CONCLUSION

The forearm muscles are significantly affected by glove tightness in performing different daily tasks that required gripping, pinching, and typing. The increase of RF of pressure gloves causes negative impact on psychophysical response and handgrip strength. Glove tightness in relation to hand performance and comfort is important in prescribing an optimal pressure therapy glove for hypertrophic scar treatment.

APPLICATION

The findings give insight into the impacts of pressure glove tightness on muscle activity, thus providing a reference for glove development.

New methods for evaluating physical and thermal comfort properties of orthotic materials used in insoles for patients with diabetes

Orthotic insoles are commonly used in the treatment of the diabetic foot to prevent ulcerations. Choosing suitable insole material is vital for effective foot orthotic treatment. We examined seven types of orthotic materials. In consideration of the key requirements and end uses of orthotic insoles for the diabetic foot, including accommodation, cushioning, and control, we developed test methods for examining important physical properties, such as force reduction and compression properties, insole-skin friction, and shear properties, as well as thermal comfort properties of fabrication materials. A novel performance index that combines various material test results together was also proposed to quantify the overall performance of the insole materials. The investigation confirms that the insole-sock interface has a lower coefficient of friction and shearing stress than those of the insole-skin interface. It is also revealed that material brand and the corresponding density and cell volume, as well as thickness, are closely associated with the performance of moisture absorption and thermal comfort. On the basis of the proposed performance index, practitioners can better understand the properties and performance of various insole materials, thus prescribing suitable orthotic insoles for patients with diabetic foot.

2D and 3D anatomical analyses of hand dimensions for custom-made gloves

Measuring hand anthropometric data for the development of good-fitting gloves is crucial. In pursuing higher accuracy in hand anthropometric measurements, scanning of hand surfaces with the aids of image analysis system to acquire measurements is an alternative to the manual methods. This study proposes a new hand measuring approach by using 2D and 3D scanning which are evaluated through comparisons of manual measurements. Thirty-three dimensions are measured by using (1) tape and calliper measurement; (2) 2D image analysis; (3) 3D image analysis based on ten captures; and (4) 3D image analysis based on three captures, respectively. Repeated-measures ANOVA, correlation analysis and RMSE are used to examine the results. The hand dimensions obtained from the four methods are highly linearly correlated. Hand data taken from 3D image analysis has no significant difference compared with manual measurements on hand and wrist circumferences, length and breadth dimension, regardless of the number of captures.