Barehanded Condition Research Articles

EFFECTS OF WRIST GUARD AND ELBOW ARREST STRATEGY ON IMPACT FORCE IN FORWARD FALLS

Wrist guards are widely used for preventing distal radius fracture during in-line skating and snowboard-related activities. However, more than half of people wearing wrist guards nonetheless sustain a fracture of the wrist in forward falls. Accordingly, this study evaluates the effects of three factors, namely the wrist guard design, the fall height and the arrest strategy, on the impact force during a forward fall onto a single outstretched hand. Fifteen physically healthy male participants volunteered for the biomechanical investigation. None of the participants had a previous history of upper extremity injuries or disorders. A 1000[Formula: see text]Hz AMTI force plate was used to measure the ground reaction force (GRF) in forward falls performed using a self-built release system onto a single hand. The GRF and impact time were analyzed in terms of three factors, namely (1) the wrist guard design, including bare hand (BH), conventional wrist guard (WG), wrist guard pad on palm (WG+), and WG+ with no lower splint (WG[Formula: see text]; (2) the elbow arrest strategy, including elbow extended and elbow flexed; and (3) the fall height, including 4[Formula: see text]cm and 8[Formula: see text]cm. The impact force and loading rate significantly increased with an increasing fall height. However, the elbow flexed strategy attenuated the GRF peak force and delayed the point of peak impact force. The GRF in the WG, WG+ and WG− conditions was significantly lower than that in the BH condition. Overall, a lower fall height, a wrist guard with a compliant pad (WG+ or WG[Formula: see text], and an elbow flexed strategy reduced the impact force, delayed the peak impact force, and reduced the loading rate in forward falls.

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

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. The wearing of pressure therapy gloves is often considered to hinder hand performance and cause discomfort, resulting in unsatisfactory treatment adherence during burn rehabilitation. 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. 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%). 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. The findings give insight into the impacts of pressure glove tightness on muscle activity, thus providing a reference for glove development.

Design options for improving protective gloves for industrial assembly work

The study investigated the effects of wearing two new designs of cotton glove on several hand performance capabilities and compared them against the effects of barehanded, single-layered and double cotton glove conditions when working with hand tools (screwdriver and pliers). The new glove designs were based on the findings of subjective hand discomfort assessments for this type of work and aimed to match the glove thickness to the localised pressure and sensitivity in different areas of the hand as well as to provide adequate dexterity for fine manipulative tasks. The results showed that the first prototype glove and the barehanded condition were comparable and provided better dexterity and higher handgrip strength than double thickness gloves. The results support the hypothesis that selective thickness in different areas of the hand could be applied by glove manufacturers to improve the glove design, so that it can protect the hands from the environment and at the same time allow optimal hand performance capabilities.

Using pliers in assembly work: Short and long task duration effects of gloves on hand performance capabilities and subjective assessments of discomfort and ease of tool manipulation

The present study investigated the effects of wearing typical industrial gloves on hand performance capabilities (muscle activity, wrist posture, touch sensitivity, hand grip and forearm torque strength) and subjective assessments for an extended duration of performing a common assembly task, wire tying with pliers, which requires a combination of manipulation and force exertion. Three commercially available gloves (cotton, nylon and nitrile gloves) were tested and compared with a bare hand condition while participants performed the simulated assembly task for 2 h. The results showed that wearing gloves significantly increased the muscle activity, wrist deviation, and discomfort whilst reducing hand grip strength, forearm torque strength and touch sensitivity. The combined results showed that the length of time for which gloves are worn does affect hand performance capability and that gloves need to be evaluated in a realistic working context. The results are discussed in terms of selection of gloves for industrial assembly tasks involving pliers.

Evaluation of anti-vibration interventions for the hand during sheet metal assembly work

Occupational use of vibrating hand tools contributes to the development of upper extremity disorders. While several types of vibration damping materials are commercially available, reductions in vibration exposure are usually tested in the laboratory rather than in actual work environments. This study evaluated reductions in hand vibration with different vibration damping interventions under actual work conditions. Three experienced sheet metal assemblers at a manufacturing facility installed sheet metal fasteners with a pneumatic tool using no vibration damping (bare hand) and each of six anti-vibration interventions (five different gloves and a viscoelastic tool wrap). Vibration was measured with tri-axial accelerometers on the tool and the back of the hand. Unweighted mean vibration measured at the hand showed reduced vibration (p<0.001) for all six interventions (range = 3.07-5.56 m/s(2)) compared to the bare hand condition (12.91 m/s(2)). All of the interventions were effective at reducing vibration at the hand during testing under usual work conditions. Field testing beyond laboratory-based testing accounts for the influences of worker, tools, and materials on vibration transmission to the body from specific work operations.

Effects of Handwear and Hand Posture on Four Performance Measures in Foil Fencing

In foil fencing, an adequate amount of hand forces and dexterity is extremely important in manipulating the foil and thus affecting the performance of a fencer. The purpose of this study was to investigate the effects of handwear of fencing gloves and posture on four performance measures in foil fencing. Eight male fencers were tested in an experiment. Four measures of fencing performance were collected and analyzed. They were the grip and pinch forces under four hand postures and the hitting scores and motion time under a fundamental attacking scenario. Analysis of variance was conducted. Duncan's multiple range tests were conducted if a significance level of 0.05 was reached. The results showed that both the handwear condition and posture were significant on the grip force. The effects of posture on grip and pinch forces were both significant. Handwear affected hitting accuracy significantly. The effect of handwear on pinch force was not significant. The hitting scores for both the glove I and II conditions were significantly higher than the bare hand condition. The results in this study supported that selection of the thinnest glove resulted in relatively better performance for the fencers.

Shock Attenuation of Various Protective Devices for Prevention of Fall-Related Injuries of the Forearm/Hand Complex

Background Attenuation of the peak impact force is essential in any protective devices for prevention of fall-related injuries. Hypothesis Common wrist guards have limited effectiveness because of the multifaceted nature of wrist injury mechanisms, and other modalities may provide enhanced shock-absorbing functions. Study Design Controlled laboratory study. Methods A free-fall device was constructed using a mechanical surrogate to simulate falling impact. At 4 different falling heights, 5 different hand conditions were tested: bare hand, a generic-brand wrist guard, a Sorbothane glove, an air cell, and an air bladder condition. The impact force from the ground and the transmitted impact force to the forearm/hand complex were simultaneously measured. Results The falling height and hand condition significantly modulated the impact responses. The padded conditions always had significantly smaller peak impact forces compared with the bare-hand condition. The wrist guard became ineffective in impact force attenuation beyond the falling height of 51 cm. On the other hand, the air bladder condition maintained less than 45% of the peak impact force of the bare-hand condition and remained below the critical value, whereas other conditions were all ineffective. Conclusion It was reconfirmed that common wrist guard design could provide limited impact force attenuation, whereas damped pneumatic springs would provide substantially enhanced shock-absorbing functions. Clinical Relevance A wrist guard incorporating volar padding with the pneumatic spring design principle might be more effective at preventing injuries than are currently available designs.

Influence on grip of knife handle surface characteristics and wearing protective gloves

Ten subjects were asked to apply maximum torques on knife handles with either their bare hand or their hand wearing a Kevlar fibre protective glove. Four knife handles (2 roughnesses, 2 hardnesses) were tested. Surface electromyograms of 6 upper limb and shoulder muscles were recorded and subject opinions on both knife handle hardness and friction in the hand were also assessed. The results revealed the significant influence of wearing gloves ( p<0.0001), knife type ( p<0.0005) and handle hardness ( p<0.005) on the applied torque. Wearing Kevlar fibre gloves greatly increased the torque independently of the other two parameters. Under the bare hand condition, a 90° ShA slightly rough handle provided the greatest torque. Subject opinion agreed with the observed effects on recorded torque values except for the hardness factor, for which a preference for the 70° ShA value over the 90° ShA value emerged.

Effects of Glove Use in a Coating Removal Task

Workers who are in maintenance and repair occupations are routinely exposed to several musculoskeletal disorder risk factors. The purpose of this study was to investigate the effects of glove use during a coating removal task, which is a common maintenance and repair task. Nine healthy subjects (5 male and 4 female) volunteered to participate in this study. The subjects removed identical painted sections using either a metal finishing (nylon) pad or a plastic scraper, while wearing one of thirteen glove conditions. The order of the glove conditions was randomized for each subject. Force exertions were monitored along with EMG readings from the finger flexors, finger extensors, biceps, and triceps. The results showed that there were significant increases in force outputs and muscle activities when using gloves as compared to a barehanded condition. There was some evidence that indicated glove material and glove thickness are important characteristics in these observations. These findings may have implications for a worker's musculoskeletal disorders risk and for glove selection guidelines in industry.

Effect of gloves on prehensile forces during lifting and holding tasks

The effect of gloves on the spatio-temporal characteristics of prehensile forces during lifting and holding tasks was investigated. Participants (n= 10) lifted a force transducer equipped object (weight = 0.29 N) with various types of gloves and barehanded using a two-fingered precision grip. Rubber surgical gloves of varied thicknesses (0.24, 0.61 and 1.02 mm) were worn to examine the effect of glove thickness on a rayon surface. It was found that grip force increased with thickness because the participants employed a higher safety margin above the minimum force required to hold the object. The safety margin for the barehanded condition was the smallest. The performance time for lifting the object was not influenced by the variation of glove thickness. The findings suggest that glove thickness, which presumably modifies the cutaneous sensation, influences grip force regulation. The effect of glove material (rubber and cotton) was also examined in relation to slippery (rayon) and non-slippery (sandpaper) surfaces. It was found that the participants used a larger grip force with the cotton glove than the rubber glove for the slippery surface, but not with the non-slippery surface. With use of the rubber glove, a relatively low grip force level was maintained for both slippery and non-slippery surfaces. The performance time for the cotton glove was longer than that for the rubber glove. The findings suggest that the rubber glove provides better efficiency of force and temporal control than the cotton glove in precision handling of small objects.

Evaluating the effects of wearing gloves and wrist support on hand–arm response while operating an in-line pneumatic screwdriver

The objective of this study is to evaluate the effects of wearing a glove and wrist support on hand–arm response while operating an in-line pneumatic screwdriver. Hand–arm response was investigated in terms of triggering finger force, flexor digitorum EMG and hand-transmitted vibration. Four glove levels (barehanded, cotton, nylon and open-finger), and two wrist support levels (wearing, and not wearing) were evaluated. Thirteen healthy male subjects drove screws into a horizontally mounted iron plate with pre-tapped screw holes using an in-line pneumatic screwdriver in the randomly ordered experimental conditions. The results indicate that wearing a nylon glove and not using a wrist support is the best combination among the eight evaluated experimental conditions. Wearing a nylon glove reduced 18.2% of the triggering force as compared with the barehanded condition. In addition, wearing a nylon glove had comparatively low forearm muscular exertion, and reduced 16% and 15% of hand-transmitted vibration in the z-axis and the sum of 3-axes as compared with the barehanded condition. The use of a wrist support required a greater triggering force and a 9.9% greater hand-transmitted vibration in the y-axis than when not using a wrist support. Relevance to industry The results of this study can be applied to the design of assembly tasks in the electronic industry to reduce the risk of incurring upper extremity cumulative trauma disorders.

The influence of gloves during maximum volitional torque exertion of supination

This study focuses on the influence of friction between gloves and handle surface during maximum volitional torque exertion of supination (S-MVTE) and under both friction-controlled and regular friction conditions. Forty student subjects (20 males and 20 females) participated in this study. Five types of gloves (surgical, single cotton, double cotton, leather, and rubber), seven handle sizes (25·4, 31·8, 38·1, 44·5, 50·8, 57·2, and 63·5 mm in diameter) and two handle shapes (cylindrical and hexagonal) were evaluated to determine their combined influences on S-MVTE. The barehanded condition was also included for comparison. The results indicate that all the main effects were significant (P< 0.001). Under friction-controlled conditions (oiled surface handle), the SMVTEs with gloves were found to be greater than the S-MVTEs of the gloveless, and the thicker the gloves, the greater the S-MVTE. On the other hand, under regular (unoiled) conditions, the S-MVTE was mainly affected by the friction between handle surface and gloves, although the interaction between gloves and handle shape was also a minor influence. A hexagonal handle produced, in all handle diameters, greater S-MVTE than a cylindrical handle. The mean S-MVTE under oiled conditions was about 53% of that of unoiled conditions. The mean SMVTE of females was about 61% of that of males.

The Effects of Gloves on Grip Strength and Muscle Activity

The focus of this research was to investigate how grip strength and forearm muscle force were affected by two types of gloves, rubber and leather. Grip strength was significantly less in the two gloved conditions than in a barehanded condition. However, EMG analysis of muscle activity revealed no significant difference in muscle activity across the gloved and barehanded conditions, indicating that subjects generated maximal exertions in all conditions. Therefore, a certain amount of muscle force is lost in the hand-glove interface while producing maximal grip forces in the gloved conditions. Internal muscle force measurement could thus be used to aid in glove selection for submaximal tasks in industry.

Glove Effect on Strength: An Investigation of Glove Attributes

A number of human performance capabilities are compromised with gloves. Explanations for the strength decrements with gloves have ranged from lack of tactile feedback when wearing gloves, to improper fit, to individual and task differences. An attempt has been made in this investigation to develop a predictive relationship between strength decrements and glove characteristics. Fifteen subjects participated in an experiment involving a grip and a grasp task with three gloves and a bare handed condition. Tenacity, snugness, suppleness and the material thickness were objectively measured as glove attributes. Significant Task and Glove effects were found. Results suggest that the glove size may not matter much in performance whereas resistance to sliding is an important performance determinant when using gloves. The results suggest that the strength decrements are complex functions of a number of glove attributes.

Manual Dexterity Evaluation of Gloves Used in Handling Hazardous Materials

The problems associated with hazardous materials control are numerous and complex. One of these problems involves selecting hand protection which will resist permeation for the duration of the exposure while maintaining sufficient levels of dexterity and tactility so that the worker can safely and efficiently perform the required task. This study investigated the effect of nine glove combinations on manual dexterity. These included three single glove and six double glove combinations plus the bare hand condition. The subjects performed a nut-bolt-washer assembly-dissassembly task using the Bennett Hand Tool Dexterity Test apparatus. The task required the use of a screw driver, two sizes of open-end wrenches, and an adjustable wrench, along with handling the bolt, nut, and washer while performing the assembly-disassembly task for three different bolt, nut, and washer sizes (1/2″, 5/16″, 1/4″). The response variables measured in the experiment were the time to complete each task and number of errors committed during each task. An error was defined as a drop of any of the items handled. The data was analyzed using a fixed effects randomized ANOVA model and the Duncan's Multiple Range Test. An alpha level of 5 per cent was used in the analysis. The results of the analyses showed that gloves increased the average completion time by 15 to 37%. Several double gloving combinations had significantly longer task completion times compared to single gloves.