Grip Pressure Research Articles

Interobserver reproducibility of the assessment of severity of complaints, grip strength, and pressure pain threshold in patients with lateral epicondylitis

Smidt N, van der Windt DA, Assendelft WJ, Mourits AJ, Devillé WL, de Winter AF, Bouter LM. Interobserver reproducibility of the assessment of severity of complaints, grip strength, and pressure pain threshold in patients with lateral epicondylitis. Arch Phys Med Rehabil 2002;83:1145-50. Objective: To evaluate the interobserver reproducibility of the assessment of severity of complaints, grip strength, and pressure pain threshold in patients with lateral epicondylitis in primary care. Design: Two physiotherapists assessed independently, and in randomized order, the severity of complaints scored on an 11-point numeric rating scale, pain-free grip strength, maximum grip strength, and pressure pain threshold. Setting: Primary care center in the Netherlands. Participants: Fifty patients were assessed by both physiotherapists. Interventions: Not applicable. Main Outcome Measures: Intraclass correlation coefficients (ICCs) and 95% confidence intervals (CIs) were calculated to assess interobserver reliability. The Bland and Altman method was used to assess interobserver agreement, which included calculation of the mean difference between the observers (d), the 95% CI for d, the standard deviation of the differences, and the 95% limits of agreement. Finally, the smallest detectable difference (SDD) was calculated. Results: The ICC for the severity of complaints was.90. The ICCs for the pain-free grip strength and maximum grip strength were.97 and.98, respectively. The pressure pain threshold showed a lower reliability (ICC=.77). The interobserver agreement for all outcome measures was good, but systematic differences in assessment between the physiotherapists were found for the maximum grip strength and pressure pain threshold. For pressure pain threshold, the SDD was clearly larger than the predefined acceptable difference of 10% of the total range of measurement. Conclusions: The interobserver reliability of severity of complaints and grip strength was excellent, whereas the pressure pain threshold showed unsatisfactory reliability. Grip strength and overall assessment of the severity of complaints are useful and reliable measures for the assessment of lateral epicondylitis. Pain-free grip strength, in particular, is relatively easy to perform and has been shown to be associated with other measures of functional disability in patients with lateral epicondylitis. We, therefore, recommend the use of pain-free grip strength in both research and clinical practice. © 2002 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation

Intelligent multifunction myoelectric control of hand prostheses

Intuitive myoelectric prosthesis control is difficult to achieve due to the absence of proprioceptive feedback, which forces the user to monitor grip pressure by visual information. Existing myoelectric hand prostheses form a single degree of freedom pincer motion that inhibits the stable prehension of a range of objects. Multi-axis hands may address this lack of functionality, but as with multifunction devices in general, serve to increase the cognitive burden on the user. Intelligent hierarchical control of multiple degree-of-freedom hand prostheses has been used to reduce the need for visual feedback by automating the grasping process. This paper presents a hybrid controller that has been developed to enable different prehensile functions to be initiated directly from the user's myoelectric signal. A digital signal processor (DSP) regulates the grip pressure of a new six-degree-of-freedom hand prosthesis thereby ensuring secure prehension without continuous visual feedback.

369 テニス打撃が肘に与える力学的影響に関する研究

Recently, it is proposed that oversized ball is used in the official games. Effects on the player in using he oversized ball are not clear still. Especially effects on the elbow have to be analyzed as soon as possible to prevent the tennis elbow. In this paper, we solve the dynamical effects on the elbow in hitting an oversized tennis ball in comparison with the normal sized ball. When a player blows the ball in the court, the acceleration and the bending angle of player's elbow, the grip pressure, and the 3-dimentional positions of a racket and a ball were measured. As the parameter, three type of the tension of the gut string were chosen. The result shows that hitting the normal sized ball at the top of the racket had more effect on the elbow.

Hyperparasitoid defense strategies against spiders: the role of chemical and morphological protection

The aphid endohyperparasitoid Alloxysta brevis (Thomson) (Hymenoptera: Charipidae) applies defensive chemicals stored in mandibular gland reservoirs against attacking ants. Alloxystines can be divided into species capable of exploiting ant-attended resources and into species exclusively reared from unattended aphid-parasitoid systems. Mandibular secretions are found in species of both groups, with little variation in chemical composition. We show that the mandibular gland secretion does not only protect against ant attacks but acts as an overall defense agent against generalist predators like spiders. The protective success differed with the spider species. The web-building spider Agelena labyrinthica (Clerck) (Araneae: Agelinidae) killed 57% of attacked A. brevis females, but sucked out only 8%. The smaller free-hunting jumping spider Salticus scenicus (Clerck) (Araneae: Salticidae) failed in overwhelming or severely injuring A. brevis. The pattern of interactions showed striking similarities with interactions between A. brevis and the ant Lasius niger (Hymenoptera: Formicidae). Primary parasitoids which are lacking chemical defense and sufficient morphological protection suffered significantly higher mortality due to spider predation. Our results indicate that - additional to chemical defense- parasitoid survival depends on the specific morphological resistance against grip pressure during capture, and on the predator - prey size relationship.

A Comprehensive risk Assessment Model for Work-Related Musculoskeletal Disorders of the Upper Extremities

A quantitative risk assessment model determining the likelihood of incurring work-related musculoskeletal disorders of the upper extremities has been developed based on grip force and hand motion data input from an innovative ‘touch glove’. This glove utilizes a commercial CyberGlove to measure hand and finger movements and UniForce pressure sensors to measure grip pressure during work. These are incorporated directly on-line to a laptop with the risk assessment model leading to a predicted incidence rate. The model explains 50% of the variance due to job stressors, with the remaining variability due to individual and psychosocial factors. These were examined in a pilot case-control retrospective epidemiological study of 97 participants, reducing the unexplained variability to almost less than 10%.

動作・生体情報処理による工作機械操作中の個人情報認識

This paper deals with personal information recognition in machine tool operation. First, a measuring system concerning a lathe was constructed. The system samples pulse, respiration, and galvanic skin response as biological information and revolution of handles and grip pressure changes as operative information. Next, the relationships between the processed indexes and personal information were investigated. A personal information identifying system, capable of recognizing, concentration, mental strain and less consciousness in real-time as well as skill of the operator during machine tool operation was developed. The results of the experiments confirm the possibility of identifying the personal information.

Molecularly Oriented Films for Space Applications

Because of their inherent toughness and flexibility, low density, thermal stability, radiation resistance and mechanical strength, aromatic polyimides have excellent potential for use as advanced materials on large space structures. Polyimides were uniaxially and biaxially oriented to further enhance their dimensional stability, stiffness, elongation and strength. Both unoriented and oriented polymeric thin films were also cryogenically treated to temperatures below -184 °C to show their stability in cold environments. Successful stretching depended on film quality, film thickness, soak time, grip pressure, stretching rate and stretching temperature. In-plane birefringence increased with increased stretch ratios as expected. Coefficients of thermal expansion (CTEs) decreased with increased stretch ratio by as much as 31%. Tensile strengths increased by up to 85% with increasing stretch ratio. Elongations increased by as much as 95% with stretching. Significant improvements in elongation were obtained with only a 2× uniaxial orientation. Moduli did not change significantly with stretching. Mechanical properties increased more with uniaxial stretching than biaxial stretching. Cryogenic treatment increased the tensile strength of some stretched samples by a maximum of 10–20%. Properties such as modulus and CTE did not change significantly after the films had been slow cooled to cryogenic temperatures.

テニスラケットの把持およびコントロール動作に関する生体力学的解析

It has been generally accepted that biomechanical analysis is an important factor in the preven-tion of sports injuries and improvement of sports skill. In all sports in which the players use rackets, the first problem all prospective players must address is the manner in which the racket is held. Tennis players continually seek added power, control and a reduction in the unpleasant vibrations produced by offcenter impacts. It is belicved that a grip-firmness on the racket at impact is one of the most important factors in determining the effectiveness of the return and that ball control of skilled players is significantly dependent on the level of grip pressure. In this study, a contact pressure measurement system using electric conductive rubber sensors was developed to study the manner of how a player can get to the ball as quickly as possible while maintaining an optimal level of grip pressure to give control and power for the stroke. The direct linear transformation technique was also applied to the motion analysis of the upper extremity during the forehand stroke. It was found that skilled players hold the racket with three fingers and clasp it gently in the palm of their hand during strokes.

Outcome assessment for carpal tunnel surgery: The relative responsiveness of generic, arthritis-specific, disease-specific, and physical examination measures

Clinical evaluation of outcome after treatment of carpal tunnel syndrome has not been standardized. To assess the value of various clinical and questionnaire measures for the assessment of outcome after carpal tunnel surgery, we surveyed 22 patients 1 day before and 3 months after carpal tunnel release with the following measures: the Medical Outcomes Study 36-item short form health survey, the Arthritis Impact Measurement Scale, the Brigham and Women's Hospital carpal tunnel questionnaire, wrist range of motion, power pinch grip strength, pressure sensibility, and dexterity. Significant changes, all in the direction of improved health status postoperatively, were noted in the following scales or measures: the Arthritis Impact Measurement Scale pain, satisfaction, health perception, arthritis impact, and symptom scales; the Brigham and Women's Hospital symptom and function scales; the short form health survey's physical role, emotional role, and bodily pain scales; and the measurement of dexterity. In this study, standardized questionnaires were more sensitive to the clinical change produced by carpal tunnel surgery than many commonly performed physical measures of outcome. The condition-specific questionnaire was more sensitive to change than were more generic questionnaires.

Biomechanical Analysis of Grasp Motion Characteristics.

This paper is concerned with biomechanical analysis of the motion characteristics for grasping a solid cylinder. Contact pressure and surface electromyogram (surface EMG) of muscle flexor digitorum superficialis during grip motion were measured using a contact pressure measurement system with pressure-sensitive conductive rubber sensors and an electromyograph, respectively. In addition, direct linear transformation (DLT) technique with a video camera system is used to analyze three-dimensional joint motion of fingers. It was found that the tips of middle finger, ring finger and thumb are mainly used to stably grip the cylinder. The experimental results also showed that grip pressure increased with an increase in the weight of the cylinder with a constant diameter.

A study of hand grip pressure distribution and EMG of finger flexor muscles under dynamic loads.

A matrix of miniature and flexible pressure sensors is proposed to measure the grip pressure distribution (GPD) at the hand-handle interface of a vibrating handle. The GPD was acquired under static and dynamic loads for various levels of grip forces and magnitudes of vibration at different discrete frequencies in the 20-1000 Hz range. The EMG of finger flexor muscles was acquired using the silver-silver chloride surface electrodes under different static and dynamic loads. The measured data was analysed to study the influence of grip force, and magnitude and frequency characteristics of handle vibration on: (i) the local concentration of forces at the hand-handle interface; and (ii) the electrical activity of the finger flexor muscles. The results of the study revealed high interface pressure near the tips of index and middle fingers, and base of the thumb under static grip conditions. This concentration of high pressure shifted towards the middle of the fingers under dynamic loads, irrespective of the grip force, excitation frequency, and acceleration levels. The electrical activity of the finger flexor muscles increased considerably with the grip force under static as well as dynamic loads. The electrical activity under dynamic loads was observed to be 1.5-6.0 times higher than that under the static loads.

Wrist kinematics differ in expert and novice tennis players performing the backhand stroke: Implications for tennis elbow

Investigators have suggested that the greater prevalence of lateral humeral epicondylitis (tennis elbow, TE) in novice tennis players compared to expert players may reflect the novice players' use of faulty mechanics for the backhand stroke. We investigated the wrist kinematics (flexion/extension), grip pressures, and wrist muscle electromyographic activity in novice ( N = 8) and expert ( N = 8) tennis players performing the backhand stroke. Experts performed the backhand stroke with the wrist extended (re: neutral alignment of the forearm and hand dorsum). Collision of the ball and racket occurred with the wrist extended an average of 0.41 rad (about 23° from neutral alignment) in the expert players; moreover, their wrists were moving further into extension at impact. In contrast, novice subjects struck the ball with the wrist flexed 0.22 rad (about 13°) while moving their wrists further into flexion. Wrist extensor EMGs showed similar levels of activity during the 500 ms interval before ball-racket impact, whereas expert subjects displayed greater EMG levels after contact, consistent with the accompanying wrist extension. The wrist kinematic and EMG data together show that the novice subjects eccentrically contracted their wrist extensor muscles throughout the stroke. We argue that conditions exist for novice subjects that assist stretch of wrist extensor muscles upon collision of the ball and racket. The resulting eccentric contraction of wrist extensor muscles may contribute to lateral TE in novice players, given previous research indicating that eccentric muscle contraction facilitates muscle fiber injury.

Grip pressure distribution under static and dynamic loading

The dynamic response of a vibrating handarm system is strongly related to the grip force. While the relationship between total grip force and vibration characteristics of the hand-arm system has been extensively studied, no attempts have been made to investigate the distribution of grip pressure at the hand-handle interface. The local grip-pressure distribution may be more closely related to the finger blood flow, fatigue and loss of productivity than total grip force. In the present study, distribution of static and dynamic forces at a hand-handle interface is investigated using a grid of pressure sensors mounted on the handle. The pressure distribution is acquired for different values of static and dynamic grip forces in the range of 25–150 N. The dynamic measurements were conducted at various discrete frequencies in the 20–1000 Hz range with peak acceleration levels of 0.5 g, 1.0 g, 2.0 g and 3.0 g. The grip-pressure distribution under static loads revealed a concentration of high pressures near the tips of the index and middle fingers, and the base of the thumb. This concentration of high pressures shifted towards the middle of the fingers under dynamic loads, irrespective of grip force, excitation frequency and acceleration levels. These local pressure peaks may be related to impairment of blood flow to finger tips and the possible causation of vibration white finger.

Force Distribution at Hand/Handle Coupling: The Effect of Handle Type

Handle location and geometry play an important role in container design and effectiveness. An ideal handle position and angle should minimize stress at L5/S1 and minimize average grip pressure on the two hands with force distributed evenly on both hands. Handles in such a position will be most comfortable for performing a MMH task and reduce the likelihood of compressive injuries on the lumbar spine. Most of the published research on container handles have used the psychophysical, biomechanical, and/or physiological methods to determine handle effectiveness. The force distribution at the exact point of energy transfer, namely the hand/handle interface has rarely been addressed by the scientific community. The intent of this study was to determine the force distribution at the hand/handle interface and use the same to compare the effectiveness of various handle types, positions, and angles. Six factors were tested in this experiment using a fractional factorial design. The pressure at the interface was measured using a number of force sensing resistors (FSRs) in each hand. The results indicate handle positions 2/2, 8/8, and 3/7 to be far superior to position 6/8. The average pressure at the FSR sites appear to be the least at handle angles of 0 degree. Further, the force distribution for the cut-out handle appears to be more uniform than that for the cylindrical handle (circular cross-section). Based on these findings recommendations are made for container designer.

Using Force Sensitive Resistors to Evaluate Hand Tool Grip Design

The pressure distribution of the hand is an important element in evaluating hand tool grip. For measuring the pressure distributions of the hand, a portable sensor glove was developed using force sensitive resistors of the conductive polymer type. Pressure distributions of three hand tools for three male subjects were measured. The pressure distribution pattern varied significantly between type of grip, location, and subjective exertion level. Factor analysis was used to identify the relative importance of each area of the hand during grip action. The results showed that there is an ‘active' area involved in gripping the hand tool and a ‘control’ area which supports the hand motion for the given task. Studies about hand tool pressure distributions will provide an important guideline in designing a new tool or improving an existing one. A microcomputer based system is being developed that records data on grip pressure distribution throughout a tool grip task. The digitized data then will be analyzed both graphically and statistically and will be used to evaluate various hand tools for industrial settings.

Study on the Gripping Peformance of Collet Chuck Holders for Machining Centers. 1st Report. Gripping Force and Gripping Pressure Distribution.

A Collet chuck holder, which can grip various rotary tools such as end mills, milling cutters, thin drills, and boring bars, is one of the most flexible tools. The holder plays a significant role as an interface between machining centers and cutting tools. However, gripping properties have not been clarified as yet. In this study, both gripping torque and gripping pressure are fundamentally investigated, in order to design a holder with high performance. In the experiments, several types of holders are tested. The single roll lock type has higher gripping torque as compared with other types, but its gripping torque is affected by the diameter and the coefficient of friction of the tool shank. In addition, with the use of a newly developed detector, the contact pressure distribution between the inner surface of the holder and the tool shank is measured. The pressure measured by means of the detector shows good agreement with the gripping torque.

The Use of Force Sensing Resistors in Ergonomic Tool Design

With more leisure time and greater reliance on the fix-it-yourself approach, more and more people, will be using hand tools. The proper ergonomic design, as related to grip force exerted and fatigue generated, is an important consideration for these tools. To measure grip force distribution, Force Sensing Resistors were calibrated appropriately, placed on two different grip type (wood and foam) and interfaced to a personal computer. Results of a lopping task, indicated a very uneven distribution in grip pressure. In all cases, grip force decreased with time while forearm flexor muscle EMG increased with time, indicating fatigue buildup. Forearm EMG for the foam grip was significantly lower than for the wooden grip. Most subjects also strongly preferred the foam grip.

Automatic injector apparatus for studying the injectability of parenteral formulations for animal health

In order to formulate suitable multidose injectable products for animal health pharmaceutical use, a knowledge of the automatic injector syringeability characteristics of parenteral formulations at wide field use temperature is desirable. The automatic injector pistol grip pressure, the limit for suitable repeat injections in the field, the relationship to injection time, and the correlation to viscosity for the multidose injectable formulations used, are the topics of this study. A Phillips MK II injector gun equipped with a 16-gauge needle and set at a 10-ml delivery volume, was used.

Grip "strength' in the healthy.

The grip pressures of a normal population were determined using a 900 mmHg column. Men were stronger than women. The dominant hand was the stronger and the difference between the dominant and nondominant hand pressures was less than 10% in both sexes. One determination of grip pressure is adequate for clinical purposes. Much information is lost if the standard 300 mm mercury or aneroid sphygmomanometers are used.

Measuring Grip Pressure during the Golf Swing

(1979). Measuring Grip Pressure during the Golf Swing. Research Quarterly. American Alliance for Health, Physical Education, Recreation and Dance: Vol. 50, No. 2, pp. 272-277.