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The rapid exchange grip strength test and the detection of submaximal grip effort
Abstract
This study assessed the reliability of the rapid exchange grip test for detecting submaximal grip effort, particularly evaluating its performance with motivated subjects with genuine hand weakness secondary to pain. Fifty normal participants performing with maximum effort then feigning hand weakness and 50 patients recovering from carpal tunnel surgery were studied. The results showed that the dynamic measure of grip strength equaled or exceeded the static measure in 28% of maximally performing participants (72% specificity), 58% of the carpal tunnel decompression patients (42% specificity), and 74% of participants giving submaximal grip effort (74% sensitivity). Sensitivities and specificities for other criteria of a positive test were also determined. Our findings suggest that the rapid exchange grip strength test cannot reliably detect voluntary submaximal effort.
... The use of such testing has limitations as certain neurological disorders will inherently be at risk for presenting with variability across tests beyond the typical allowable 20% including multiple sclerosis and myasthenia gravis. Historically, grip strength testing via dynamometer using a device such as a Jamar TM device (Taylor & Shechtman, 2000;Westbrook, Tredgett, Davis, & Oni, 2002) has been performed by having the patient do three repetitions at any setting and making sure that the grip strength did not vary more than 20% and/or generated a bell-shaped curve if all five positions were tested and peaks strength testing at grip position three assuming full effort. The rapid exchange grip (REG) method has also been described and found to be more difficult to falsify than grip strength testing via dynamometer. ...
... The rapid exchange grip (REG) method has also been described and found to be more difficult to falsify than grip strength testing via dynamometer. The REG may be a more valid measure of the degree of grip effort; however, one of the limitations is that there is no standardized test protocol for this specific examination technique (Taylor & Shechtman, 2000;Westbrook, Tredgett, Davis, & Oni, 2002). It should also be noted, however, that some studies have shown a negative impact of pain, as well as depression, on the outcomes of REG testing (Phillips, Biland, Costa, & Souverain, 2011). ...
... It should also be noted, however, that some studies have shown a negative impact of pain, as well as depression, on the outcomes of REG testing (Phillips, Biland, Costa, & Souverain, 2011). Furthermore, other studies have found that the REG strength test cannot reliably detect voluntary submaximal effort (Westbrook, Tredgett, Davis, & Oni, 2002). ...
Background:
The assessment of any patient or examinee with neurological impairment, whether acquired or congenital, provides a key set of data points in the context of developing accurate diagnostic impressions and implementing an appropriate neurorehabilitation program. As part of that assessment, the neurological physical exam is an extremely important component of the overall neurological assessment.
Purpose:
In the aforementioned context, clinicians often are confounded by unusual, atypical or unexplainable physical exam findings that bring into question the organicity, veracity, and/or underlying cause of the observed clinical presentation. The purpose of this review is to provide readers with general directions and specific caveats regarding validity assessment in the context of the neurological physical exam.
Conclusions:
It is of utmost importance for health care practitioners to be aware of assessment methodologies that may assist in determining the validity of the neurological physical exam and differentiating organic from non-organic/functional impairments. Maybe more importantly, the limitations of many commonly used strategies for assessment of non-organicity should be recognized and consider prior to labeling observed physical findings on neurological exam as non-organic or functional.
... Although studies in larger cohorts might find additional significant differences between groups, this will not be helpful in the clinical setting, where each decision has to be made on an individual case basis. Small mean differences with large overlap and scatter hold little or no information applicable to individual cases, as previous studies have also clearly stated (Tredgett and Davis, 2000;Westbrook et al., 2002). For example, despite the significant difference we found in maximum grip strength during REG, this parameter cannot be used for individual decision, as grip strength is strongly dependent on the degree of injury. ...
... Our results are mainly in line with the findings of the few studies which have included both healthy participants and patients (Hildreth et al., 1989;Joughin et al., 1993;Tredgett and Davis, 2000;Westbrook et al., 2002). Only one of these studies claimed to have found a protocol for the detection of feigning (Hildreth et al., 1989), whereas the others have stated that the methods used were not sufficient to separate feigning healthy participants from sincere patients. ...
Detecting submaximal effort when testing grip strength is difficult. Research so far has focused on the discrimination between sincere and feigning healthy participants, whereas the clinically relevant distinction is between injured patients and feigning participants. The aim of our study was to compare rapid exchange grip and isometric grip strength testing in 41 participants feigning weakness with 39 patients with decreased hand function. Various parameters that describe grip strength were recorded and tested for differences between the groups. Only the maximum grip strength during rapid exchange grip was found to be significantly higher in feigning participants compared with patients, but this cannot be used for decision-making on an individual basis. We found no parameters that are useful for the detection of feigned weakness in an individual case.
Level of evidence:
III.
... Some methods such as electromyography [6,7], the torque-velocity test [8] and the forcetime curve test [9,10] are complex and require lengthy time to administer. In clinical practice, however, methods that are simple, affordable and easy to be administered such as the five-rung grip test [11,12], the rapid exchange grip test [13,14], and the coefficient of variation [15,16] are commonly used for detecting SOE. ...
... There are various assessments commonly used in determining SOE in a clinical setting [11][12][13][14][15][16]. ...
Background
Several grip strength tests are commonly used for detecting sincerity of effort. However, there is still no widely accepted standardized sincerity of effort test. Therefore, this study aimed to examine whether grip strength test in three wrist positions could distinguish between maximal and submaximal efforts.
Methods
Twenty healthy individuals (10 men and 10 women) with a mean age of 26.7 ± 3.92 years participated in this study. All participants completed two test conditions (maximal and submaximal efforts) in three wrist positions (neutral, flexion, and extension) using both hands. Each participant exerted 100% effort in the maximal effort condition and 50% effort in the submaximal effort condition. The participants performed three repetitions of the grip strength test for each session.
Results
The results showed that there is a significant main effect of the type of effort (p < 0.001), wrist position (p < 0.001), and hand (p = 0.028). There were also significant types of effort and wrist position interactions (p < 0.001) and effort and hand interactions (p < 0.028). The results also showed that grip strength was highest at the wrist in neutral position in both the maximal and the submaximal effort condition. Grip strength values of the three wrist positions in the maximal effort condition were noticeably greater than those in the submaximal effort condition.
Conclusion
The findings of this study suggest that grip strength test in three wrist positions can differentiate a maximal effort from a submaximal effort. Thus, this test could potentially be used to detect sincerity of effort in clinical setting.
... In functional activities, grip needs to be employed in many different ways, such as sustained over a more extended period or repeatedly applied. GripAble provides a range of grip tests, including but not limited to grip endurance, sustained gripping, grip in various forearm rotational positions (LaStayo 2001), rapid exchange (Westbrook et al., 2002) and sine wave grip accuracy tests (Rinne et al. 2018), to allow for a more holistic view of hand function. Ultimately, this opens the opportunity for a deeper understanding of the association between grip and functional performance, where the multiple aspects of grip may uncover such associations. ...
Introduction: Maximal grip strength (MGS) is a reliable biomarker of overall health and physiological well-being. Therefore, an accurate and reliable measurement device is vital for ensuring the validity of the MGS assessment. This paper presents GripAble, a mobile handgrip device for the assessment of MGS. GripAble’s performance was evaluated using an inter-instrument reliability test against the widely used Jamar PLUS+ dynamometer.
Methods: The MGS data from sixty-three participants (N = 63) measured using GripAble and Jamar PLUS+ were collected and compared. Intra-class correlation (ICC) was performed to evaluate the inter-device reliability between GripAble and Jamar PLUS+. The influence of gender and hand on MGS were also analysed.
Results: GripAble demonstrates good-to-excellent inter-instrument reliability to the Jamar PLUS+ (ICC 3,1 =0.906). There were significant differences in the mean MGS between GripAble and Jamar PLUS+ (p <0.001 for both). GripAble’s measurement output is equivalent to 69% ([68-71]%) of Jamar PLUS+’s measurement output. The average difference in mean MGS between the two devices was 10.84 ± 4.18 kg ([4.77-18.54] kg), which increases with higher MGS. There were also significant differences in MGS between male and female and between right and left hands measured using GripAble and Jamar PLUS+ (p <0.001 for all comparisons).
Conclusion: GripAble has good-to-excellent inter-device reliability with Jamar PLUS+, suggesting that it can be used clinically as a dynamometer whilst also providing additional functionalities, such as remote assessment, objective evaluation of compliance to standard protocol and assessing multiple facets of grip strength beyond the standard single maximum grip test. Normative MGS data using GripAble should be collected and integrated into the software for immediate comparison. Further studies, including test-retest and inter-rater reliability of using GripAble, are discussed. 1 www.gripable.co BMC Musculoskeletal Disorders-GripAble vs Jamar v1.0 15/07/2021
... Instead, the integrated sensors within the GripAble device and software can facilitate therapists in tracking user compliance to the standard grip strength protocol by analysing hand pose, the time-varying force profile and associated timings of key events, such as rise time, peak force and decay period. Moreover, the software can be used to provide a variety of grip strength measures, including but not limited to, grip endurance, sustained gripping, rapid exchange, 39 gripping rotatory impaction 40 and sine wave grip dexterity tests. 41 Ultimately, these will provide a holistic and objective view of hand function, which is of paramount importance, especially when normal face-to-face observational assessments can no longer be routinely performed. ...
Introduction
Grip strength is a reliable biomarker of overall health and physiological well-being. It is widely used in clinical practice as an outcome measure. This paper demonstrates the measurement characteristics of GripAble, a wireless mobile handgrip device that measures grip force both isometrically and elastically-resisted for assessment and training of hand function.
Methods
A series of bench tests were performed to evaluate GripAble's grip force measurement accuracy and sensitivity. Measurement robustness was evaluated through repeated drop tests interwoven with error verification test phases.
Results
GripAble's absolute measurement error at the central position was under 0.81 and 1.67 kg (95th percentiles; N = 47) when measuring elastically and isometrically, respectively, providing similar or better accuracy than the industry-standard Jamar device. Sensitivity was measured as 0.062 ± 0.015 kg (mean ± std; 95th percentiles: [0.036, 0.089] kg; N = 47), independent of the applied force. There was no significant performance degradation following impact from 30 drops from a height >1.5 m.
Conclusion
GripAble is an accurate and reliable grip strength dynamometer. It is highly sensitive and robust, which in combination with other novel features (e.g. portability, telerehabilitation and digital data tracking) enable broad applicability in a range of clinical caseloads and environments.
... In functional activities, grip needs to be employed in many different ways, such as sustained over a more extended period or repeatedly applied. Gri-pAble provides a range of grip tests, including but not limited to grip endurance, sustained gripping, grip in various forearm rotational positions [26], rapid exchange [27] and sine wave grip accuracy tests [28], to allow for a more holistic view of hand function. Ultimately, this opens the opportunity for a deeper understanding of the association between grip and functional performance, where the multiple aspects of grip may uncover such associations. ...
Introduction
Maximum grip strength (MGS) is a reliable biomarker of overall health and physiological well-being. Therefore, an accurate and reliable measurement device is vital for ensuring the validity of the MGS assessment. This paper presents GripAble, a mobile hand grip device for the assessment of MGS. GripAble’s performance was evaluated using an inter-instrument reliability test against the widely used Jamar PLUS+ dynamometer.
Methods
MGS data from sixty-three participants ( N = 63, median (IQR) age = 29.0 (29.5) years, 33 M/30 F) from both hands using GripAble and Jamar PLUS+ were collected and compared. Intraclass correlation (ICC), regression, and Bland and Altman analysis were performed to evaluate the inter-instrument reliability and relationship in MGS measurements between GripAble and Jamar PLUS+ .
Results
GripAble demonstrates good-to-excellent inter-instrument reliability to the Jamar PLUS+ with ICC 3,1 = 0.906 (95% CI [0.87—0.94]). GripAble’s MGS measurement is equivalent to 69% (95% CI [0.67—0.71]%) of Jamar PLUS+’s measurement. There is a proportional difference in mean MGS between the two devices, with the difference in MGS between GripAble and Jamar PLUS+ increasing with MGS.
Conclusion
The GripAble is a reliable tool for measuring grip strength. However, the MGS readings from GripAble and Jamar PLUS+ should not be interchanged for serial measurements of the same patient, nor be translated directly from one device to the other. A new normative MGS data using GripAble will be collected and accessed through the software for immediate comparison to age and gender-matched subpopulations.
... Beim schnellen Wechselgriff wird die Griffkraft im schnellen Wechsel zwischen linker und rechter Hand gemessen. Westbrook et al. [35] und Joughin et al. ...
Background:
Grip strength measurement is a widely used method for clinical as well as scientific purposes. In hand surgery, it is an essential component in the diagnosis of disease, treatment sequences and assessment. In epidemiological studies, it is a good predictor of healthy ageing or disease progression.
Problem:
Measurement results and their interpretation can be influenced by many factors. The historical development of dynamometry, measurement technology and the standard values in various population groups are presented. Comparisons with standard values should only be made using current tables because the grip strength has changed in recent decades. Assessment of the voluntarily submaximal grip strength remains problematic. Proposals are made for how to assess grip strength during the evaluation.
... However, these tests require cooperation from the patients. Studies suggest that rapid, exchange or repeated measurement of MHGS test is not a reliable discriminator of true and confabulated hand weakness (30) and cannot reliably detect voluntary submaximal effort (31). On the other hand, measuring hand width does not require any form of dynamic participation and cooperation in testing from the patient. ...
Background:
To identify physical measures that predict maximal handgrip strength (MHGS) and provide evidence for identifying lack of maximum effort with assessing upper extremity weakness.
Objective:
This study investigated anthropometric measurements associated with MHGS of healthy young adults.
Methods:
A convenience sample of 150 healthy adults ages 19 to 34 years old completed the MHGS assessment, which was measured using a Jamar dynamometer according to the protocol of the American Society of Hand Therapists, for both dominant and non-dominant hands. Several anthropometric data points were collected, which included height, body weight, forearm length, forearm circumference, hand length, and hand width.
Results:
Multivariable linear regression analysis indicated gender and hand width were uniquely and significantly associated with participants' MHGS for dominant and non-dominant hand and accounted for more than 60% of the variance, with R2 = 0.60, P < 0.001 for the dominant hand model and R2 = 0.64, P < 0.001 for the non-dominant hand model.
Conclusions:
Hand width is the best predictor of MHGS in both the non-dominant and dominant hands for healthy young adults.
... Many studies pointed that if hand tools have poor ergonomics, then workers' hands and forearms become increasingly subject to a variety of work related musculoskeletal disorders by cumulative trauma such as: tendonitis, strained muscles, carpal tunnel syndrome, nerve impingement, and many others (Kelly et al., 1995;Kattel et al., 1996;Wells and Keir, 1999;Sande et al., 2001;Mirka et al., 2002;Boyles et al., 2003). Therefore, pinch grip force evaluation in the workplace may help in three main aspects, which are: identifying individuals at risk for work related musculoskeletal disorders of the hands and forearms, determining the improvement made over the process of treatment or rehabilitation, and assessing feigned injury (Boissey et al., 1999;Greeves et al., 1999;Abbott et al., 2001;Peolsson et al., 2001;Tredgett and Davis, 2000;Westbrook et al., 2002;Kong et al., 2012). ...
... Unfortunately, the CV method did not have adequate sensitivity and specificity to differentiate between MVE and IM performance (Shechtman et al., 2006). Other strength methods such as the rapid exchange grip test have also been evaluated ( Westbrook, Tredgett, Davis, & Oni, 2002), but to date none have satisfied both essential criteria for a valid objective method (Robinson & Dannecker, 2004). One method with potential application for detecting IM within paralympic sport, which has not been previously evaluated for this purpose, is Fitts' law. ...
In paralympic classification, tests of impaired coordination (e.g., reciprocal tapping tasks) are effort dependent and therefore susceptible to intentional misrepresentation of abilities (IM)-deliberate exaggeration of impairment severity. The authors investigated whether reciprocal tapping tasks performed submaximally could be differentiated from tapping tasks performed with maximal voluntary effort, based on conformity with Fitts' law. Ten nondisabled participants performed 14 tapping tasks with their dominant hand on 3 separate occasions. Seven tasks were performed with MVE and the other 7 at speeds that were at least 20% slower. Results revealed that evaluating conformity with Fitts' law is a potentially valid method for objectively detecting IM during reciprocal tapping. Evaluation of sensitivity and specificity of the method is now warranted.
Link to record in UQ espace: https://espace.library.uq.edu.au/view/UQ:362682
... This is the standard position to assess the hand grip force, proposed by the American Society of Hand Therapists (ASHT), supported by the research results of other scientists. (7,19) During the measurements, the participants were blindfolded and did not receive any feedback on the course of trial or their scores. An electronic hand dynamometer (Baseline Hydraulic Hand Dynamometer; Fabrication Enterpirses Inc., Irvington, NY, USA) with Hercules 2000 software, JAMAR Handy (Orthopartner AG, Seon, South Korea) was used for measurement (see Figure 3). ...
Background:
Swedish massage is one of the common treatments to provide optimal start and readiness of athletes. The ability of kinesthetic differentiation (KD) is crucial in sport performance. This skill allows to adapt demanded muscle forces to optimize the motor tasks, and it is responsible for the precision. In the literature, there is no evidence how Swedish massage influences the kinesthetic differentiation.
Purpose:
The objective of the study was to evaluate the impact of Swedish massage on the kinesthetic differentiation and muscle strength of hand grip.
Methods:
Thirty participants took part in this investigation (17 women and 13 men). The assessment consisted of KD tests conducted on the dominant (DH) and nondominant hand (NDH) after 15 minutes of hand and forearm Swedish massage. The procedure consisted of 13 trials for each extremity. The first three were done for 100% of the participants’ capabilities (F max ), the next five trials were done using 50% of maximum force (50% of F max ), and in the last five trials, the participants tried to use only 50% of their previous force (1/2 of 50%). Finally, the absolute force production error (FPE) was calculated for 50% (FPE_50%) and 25% (FPE_25%).
Results:
The two-way repeated measure analysis of variance ANOVA did not reveal any statistically significant changes in maximal strength grip and KD between pre- and postmassage intervention in both DH and NDH hand. Correlations showed strong relationship between pre- and postmassage for maximum force ( r = 0.92, p = .01 for DH, and r = 0.94, p = .01 for NDH), and only for the FPE_50% ( r = 0.67, p = .01 for DH, and r = 0.71, p = .01 for NDH).
Conclusions:
The results obtained indicated that the application of the Swedish massage did not affect the kinesthetic differentiation in this particular young adult group.
... Badana kończyna powinna być przywiedziona do tułowia, zgięta w stawie łokciowym do około 90 stopni, z przedramieniem w ustawieniu neutralnym, z ręką w lekkim zgięciu grzbietowym (0 -30°). Taki sposób pomiaru został poparty badaniami wielu naukowców [11][12][13][14]. ...
Streszczenie Wprowadzenie. Masaż oraz krioterapia to powszechnie stosowane środki z zakresu odnowy biologicznej. Dotychcza-sowe badania oceniały zazwyczaj skuteczność obu tych zabiegów stosowanych oddzielnie. Masaż lodem łączy działanie zimna z bodźcami mechanicznymi. Niewiele jest doniesień naukowych na temat wpływu tej formy krioterapii na parametry siłowo-szybkościowe mięśni. Cel Pracy. Zbadanie wpływu masażu lodem na gradient narastania siły chwytu. Materiał i metody. W badaniach wzięło udział 40 celowo wybranych zdrowych studentek Akademii Wychowania Fi-zycznego w Katowicach (średnia ±sd; wiek: 21,2 ±1,57 lat, wysokość ciała: 166,9 ±6,59 cm, masa ciała: 61, 15 ±10,33 kg). Grupa została losowo podzielona na dwie równoliczne podgrupy, w których jedna stanowiła grupę kontrolną, a druga została poddana masażowi z użyciem lodu. Testy siły chwytu przeprowadzono przy pomocy ręcznego dynamometru elektronicz-nego. Osoby badane wykonywały uściski ręki, z maksymalną siłą, przez okres 10 sekund, w rytmach 1 sekunda – uścisk oraz 1 sekunda – przerwa. Masaż przeprowadzono na przedniej (5 min) i tylnej (5 min) stronie przedramienia kończyny niedominującej. W grupie kontrolnej zastosowano 10-minutowy, bierny odpoczynek w pozycji siedzącej, z przedramionami opartymi na stole. Wyniki. Przeprowadzona analiza wariancji dla powtarzanych pomiarów 2 x 2 ANOVA nie wykazała istotnego statystycz-nie zróżnicowania gradientu narastania siły chwytu zarówno w grupie poddanej interwencji masażem lodem (p = 0, 319), jaki i w grupie kontrolnej (p = 0,999). Wnioski. Zastosowany masaż lodem nie wpływa w sposób istotny na gradient narastania siły chwytu w badanej grupie młodych kobiet. Abstract Introduction. Massage and cryotherapy are two commonly used recovery-inducing treatments. Previous examinations assessed efficiency of both these interventions when applied separately. Ice massage combines the effects of low temperature with mechanical stimuli. There has been scarce evidence how the above said form of cryotherapy impacts muscle strength-speed parameters. Purpose. The aim of the study was to evaluate the impact of ice massage on hand grip force gradient increase. Materials and methods. The study group consisted of 40 purposely selected healthy female students of the Academy of Physical Education in Katowice (mean ±sd; age: 21.2 ±1.57 years old, height: 166.9 ±6.59 cm, and body mass: 61.15 ±10.33 kg). The half of the group was randomly subjected to ice massage, while the other half formed a control group. The hand grip force test consisted in a 10-second performance of maximum force hand grips in isometric conditions. The contraction time of 1 sec alternated with a 1 sec rest period. An electronic hand dynamometer was used for measurements. Ice massage prior to the second measurement was performed on the front (5 min) and back side (5 min) of the forearm of the non-dominant limb. Control group had a 10-minute passive rest in a sitting position with forearms resting on a table. Results. The variance analysis of repeated measurements 2 x 2 ANOVA did not reveal any statistically significant differentiation of hand grip force gradient increase in both ice-massaged group (p = 0.319), and control group (p = 0.999). Conclusions. The results indicate that the ice massage did not significantly affect hand grip force gradient increase in the examined group of young females.
... The authors have not identified any studies which unequivocally support the use of the most prevalent methods of classifying validity of effort during hand strength assessment, namely the coefficient of variation (CV), REG testing and various methods of assessing the "Bell-Shaped Curve." Many studies and literature reviews have found these methods to be inaccurate for classifying effort during a hand strength assessment [1,3,4,[6][7][8]10,12,18,21,22,[26][27][28][29][30][31][32][33][34]36,37,[41][42][43]47]. ...
1. To determine if scores on pain questionnaires and overt behaviors during a functional capacity evaluation (FCE) were related to variability between repeated measures during a hand strength assessment. 2. To determine if failure of statistically-based validity criteria, as proposed by Schapmire, St. James and Townsend et al. [26] is likely to be due to pain.
200 consecutive clients presenting for an FCE.
Subjects filled out pain questionnaires, were observed for various behaviors and were administered the distraction-based hand strength assessment.
Clients failing two or more of the statistically-based validity criteria had higher scores on most pain questionnaires, presented with a higher frequency of various pain behaviors (p < 0.05 and < 0.001, respectively), and had a lower rate of relevant surgeries (p < 0.001). There was no statistically significant difference in the number of failed validity criteria between this group of clients and for normal subjects feigning weakness in a controlled study (p> 0.05).
Pain does not reasonably explain the failure of the statistically-based validity criteria. The protocol is appropriate for use in a client population.
Introduction
Little is known about the relationship between the types of grip strength, functional range, anthropometric measures, and function in the home and workplace. The study aimed to determine their relationships and explore their contributions to performing usual work duties and overall function in participants with and without hand and wrist injury.
Method
Forty-four participants were measured on Maximal Voluntary Isometric Grip Strength, Rapid Exchange Grip Contractions and Isometric Endurance, Forearm Length and Volumetry, and the Dart Thrower’s Motion (DTM) measure. They completed the Patient Rated Wrist and Hand Evaluation and the Disabilities of the Arm, Shoulder and Hand Work Module.
Results
The grip measures significantly correlated with Volumetry (r = 0.62–0.74) in participants with and without hand and wrist injury. The Isometric Endurance and DTM measure of the non-injured hand were found to be contributing factors for participants with hand and wrist injury when returning to usual work duties and overall function.
Conclusion
The non-injured hand function plays a role in the overall function for participants with hand and wrist injuries. Isometric Endurance and DTM measure could assist clinicians in determining suitable rehabilitation targets, resulting in a better function required for occupations in the home or workplace.
Measurement of grip strength using a handheld dynamometer is frequently performed as part of an orthopedic upper extremity examination. We review the technique of grip strength measurement and evaluation of the possible submaximal effort. What constitutes normal grip strength in one part of the world is not necessarily normal elsewhere. Additionally, there is considerable evidence, most of which is outside the orthopedic literature, that diminished grip strength is a proxy for poor health and a predictor of increased mortality.
Die Kraftverteilung einer gesunden Hand unterscheidet sich bei submaximaler Testleistung signifikant vom dem einer maximalen Leistung. Die meisten statistischen Auffälligkeiten werden hierbei beim großen Zylinder nachgewiesen und die wenigsten beim Verwenden des kleinsten Zylinders. Überraschenderweise sind Abweichungen im Kraftverteilungsmuster größer, wenn die rechte anstatt der linken Hand eine submaximale Kraftleistung erbringt. Die Kraftverteilung zwischen den Händen ist sehr ähnlich, wenn diese maximale Kraft ausüben. Aus diesem Grund kann oder muss eine gesunde Gegenseite zum Vergleich herangezogen werden, um einen Unterschied in der Kraftverteilung zu erkennen. Die Kraftverteilung zwischen Individuen variiert sehr stark. Es existiert kein universelles submaximales Kraftverteilungsmuster, sondern ein individuelles Muster. Daher ist es nicht möglich, einen Simulanten anhand eines typischen Betrugsmusters zu identifizieren.
Purpose:
This study aims to investigate if the hands' load-distribution pattern differs during maximal and submaximal grip.
Methods:
Fifty-four healthy subjects used the 200-mm Manugraphy cylinder to assess the load-distribution pattern of both hands. On 2 testing days, the subjects performed grip-force testing: 1 hand with maximal effort and the other with submaximal effort. Sides changed for the second testing day. The whole contact area of the hand was sectioned into 7 anatomical areas, and the percent contribution of each area, in relation to the total load applied, was calculated. Maximal and submaximal efforts were compared across the 7 areas in terms of load contributions.
Results:
Comparing maximum effort of the left and right hand, the load distribution was very similar without statistically significant differences between the corresponding areas. Comparing the maximal and the submaximal effort for each hand, 4 (left) and 5 (right) of the 7 corresponding areas showed statistically significant differences. Comparing the right hand, performing with maximal effort, with the left hand, performing with submaximal effort, 5 areas varied significantly. With the right hand performing submaximal effort, all 7 anatomical areas were significantly different.
Conclusions:
The load distribution of a healthy hand is different when performing with submaximal effort compared with maximal effort. To analyze a hand's load-distribution pattern, the opposite hand can be used as a reference.
Clinical relevance:
The hand's load-distribution pattern may be a useful indication of submaximal effort during grip-force testing.
In the assessment of hand and upper limb function, detecting sincerity of effort (SOE) for grip strength is of major importance to identifying feigned loss of strength. Measuring maximal grip strength with a dynamometer is very common, often combined with calculating the coefficient of variation (CV), a measure of the variation over the three grip strength trials. Little data is available about the relevance of these measurements in patients with median nerve impairment due to the heterogeneity of patient groups. This study examined the reliability of grip strength tests as well as the CV to detect SOE in healthy subjects. The power distribution of the individual fingers and the thenar was taken into account. To assess reliability, the measurements were performed in subjects with a median nerve block to simulate a nerve injury. The ability of 21 healthy volunteers to exert maximal grip force and to deliberately exert half-maximal force to simulate reduced SOE in a power grip was examined using the Jamar® dynamometer. The experiment was performed in a combined setting with and without median nerve block of the same subject. The force at the fingertips of digits 2–5 and at the thenar eminence was measured with a sensor glove with integrated pressure receptors. For each measurement, three trials were recorded subsequently and the mean and CV were calculated. When exerting submaximal force, the subjects reached 50–62% of maximal force, regardless of the median nerve block. The sensor glove revealed a significant reduction of force when exerting submaximal force (P1 sensor) with (P < 0.032) and without median nerve block (P < 0.017). An increase in CV at submaximal force was found, although it was not significant. SOE can be detected with the CV at the little finger at using a 10% cut-off (sensitivity 0.84 and 0.92 without and with median nerve block, respectively). These findings suggest low reliability of the power grip measurement with the Jamar® dynamometer, as well as that of the CV for detecting SOE. However, the combination of finger forces including the thenar area and the CV at the little finger could lead to better reliability for detecting feigned reduction of grip strength. The methods were as reliable in subjects with a median nerve block as in healthy subjects.
The concept of impairment/disability/handicap was proposed by the world health organization to measure disease, handicap and health. We have used this concept in the evaluation of disorders of the hand and wrist. Impairment can be determined by measuring the range of motion and the gripping force. Disability is measured with a validated questionnaire (the "DASH"). We found a significant but weak correlation between (limited) wrist motion and DASH score and a significant but stronger correlation between gripping force and DASH. It is obvious that in clinical research it is absolutely necessary to indicate what is measured.
Our goal was to investigate an improvement in hand strength and its associated factors after carpal tunnel decompression in patients with carpal tunnel syndrome.
Muscle strength capabilities are a determinant in the ability to successfully accomplish everyday tasks. As such, the quantification of this aspect of human performance is of interest in many settings. Currently, the validity of muscle strength test results is reliant on the notion that during testing, the participant exerted an effort that is sincere, and that consisted of maximal voluntary contractions. Therefore, the ability to differentiate between maximal and non maximal muscular exertions is of importance. The purpose of this dissertation was to develop and validate probability-based decision rules for differentiating between maximal and non-maximal voluntary exertions of the knee and shoulder joint musculature during isokinetic dynamometry-based testing. For development of the decision rules, healthy participants performed a series of maximal and non-maximal exertions at different testing velocities through a prescribed range of motion. Two different theory-based approaches were subsequently used for decision rule development: the first approach was based on expected better consistency in strength waveform shapes and relative magnitudes during performance of maximal efforts in comparison to non-maximal efforts. The second approach was based on the known force-velocity dependency in skeletal muscles. In terms of discriminatory performance, several of the decision rules pertaining to the knee joint markedly improve upon those previously reported. In addition, a separate investigation demonstrated that the decision rules offer excellent discriminatory performance when applied to test results of participants that have undergone surgical reconstruction of their anterior cruciate ligament. As such, clinicians and researchers may be able to ascertain voluntary maximal effort production during isokinetic testing of the knee joint musculature with a high degree of confidence, and thus be able to rely on such scores for decision-making purposes. With regards to the shoulder musculature decision rules, several methodological issues related to test positioning and signal processing need to be addressed prior to consideration of their use in the clinical domain.
Studies of grip strength typically examine maximum force during a single repetition, but this type of exertion is relatively rare in the workplace, where tasks frequently involve repeated forceful dynamic grasping or prolonged static holding. This study examined grip strength and endurance in three experiments: single-repetition, 10-repetition, and 30-second static hold. The relationships between anthropometric variation and grip performance were assessed for 51 individuals, aged 18–33. Measurements of the forearm and hand were found to be better predictors of grip strength than were height and weight. The ability to predict strength was most accurate for the single-repetition, and then declined with increasing duration of the experiment. Compared to univariate measurements, multivariate analysis (principal components) slightly improved the ability to predict absolute grip force. In contrast to strength, anthropometric variation was completely unassociated with relative grip endurance (percent change in force production). While larger males produced greater average grip force than did females, no significant differences existed between the genders in measures of relative endurance. The dominant hand was significantly stronger than the opposite hand, but also fatigued more rapidly. This trend was more pronounced in females than in males.Relevance to industryGrip strength and relative endurance may both contribute to the risk of work-related accidents and cumulative musculoskeletal injury. Because grip force and endurance are unrelated, ergonomists should consider which factor is most important and appropriate for their design and research goals.
Läsionen des Nervus medianus schränken die Greiffunktion der Hand erheblich ein. Die daraus resultierenden Funktionsausfälle der Hand wurden durch biometrische Messungen in vivo objektiviert. Hierzu wurden die Auswirkungen einer simulierten tiefen Medianusläsion durch Blockade des Nervus medianus mit Lokalanästhetikum auf die Kraftverteilungsmuster der Hand, auf die Greifkraft bei verschienenen Greifformen sowie die Auswirkung auf die Steuerung der Greifkraft mittels des TUB-Sensorhandschuhs untersucht. Durch Drucksensoren wurden die Kraftwerte, die während des Kraftgriffs an unterschiedlich großen Greifkörpern von den Fingern ausgeübt wurden, in Echtzeit aufgezeichnet. Um die Auswirkungen einer distalen Medianusblockade auf die ausgeübte Maximalkraft und auf die willentlich submaximale Kraftausübung während verschiedener Greifformen (Spitz-, Präzisions-, Schlüssel- und Kraftgriff sowie palmare Abduktion des Daumens) zu analysieren, wurden die mittels eines Kneif- und Hanteldynamometers gemessenen Kraftwerte der Versuchsreihen mit und ohne Nervenbetäubung einerseits für maximale und andererseits für submaximale Krafterzeugung miteinander verglichen. Mithilfe dieses Versuchsaufbaus kann somit tendenziell zwischen maximaler Kraftausübung unter Medianusblock und einer absichtlich durchgeführten submaximalen Kraftausübung bei vollständig erhaltener Medianusfunktion unterschieden werden. Dies lässt den Schluss zu, dass die Steuerung der Kraftregulation an der Hand nicht ausschließlich von sensiblen Afferenzen, sondern in erheblichem Umfang von motorischen Afferenzen in der Unterarm- und intrinsischen Muskulatur abhängig ist.
This study verifies clinical results of using a polydioxanone (PDS) tent without a guided tissue regeneration (GTR) membrane for root coverage.
Forty-nine gingival recessions (in 16 patients) were treated with a PDS tent inserted under the coronally positioned gingival flap. The recession level (RL), probing depth (PD), and keratinized mucosa width (KMW) were registered. Statistical analysis was performed with the Wilcoxon test.
In 48 cases, there was a significant reduction in the RL (2.55 +/- 1.11 mm on day 0 and 0.34 +/- 0.65 mm on day 120; P = 0.0001). PD showed the same values at the beginning and end of treatment in 47 cases (0.99 +/- 0.71 mm on days 0 and 120; z = 0.000). There was a significant increase of KMW in 46 cases (2.38 +/- 0.76 mm on day 0 and 3.18 +/- 0.90 mm on day 120; P = 0.0001).
The association of the PDS tent without the GTR membrane to a coronal sliding flap for root coverage of Miller Class I and II gingival recessions allows root coverage, gain of attachment level, and an increase of keratinized mucosa. For root coverage, it is not necessary to use the GTR membrane associated to the PDS tent, thereby reducing surgical costs. Future studies should be conducted to assess the sole performance of the PDS as an alternative method to a connective tissue graft and coronal sliding flap, thus decreasing risks and post-surgery discomfort.
To evaluate plasma sTNFR-1 and IL-6 levels and correlate with hand grip in the institutionalized and community living Brazilian elderly.
A convenience sample of 110 elderly women (71.17 + or - 7.44 years) was selected. Plasma sTNFR-1 and IL-6 levels were measured by ELISA. For the measurement of hand grip, a JAMAR dynamometer was used.
Plasma concentrations of inflammatory markers were significantly higher in institutionalized elderly (sTNFR-1: 479 + or - 22 pg/mL; IL-6: 6.3 + or - 0.8 pg/mL) than in community-dwelling elderly (sTNFR-1: 329 + or - 24 pg/mL; IL-6: 2.5 + or - 0.4 pg/mL; P < 0.0001). Institutionalized elderly had reduced hand grip (15 + or - 0.8 Kgf) in comparison to community dwelling elderly (23 + or - 0.6 Kgf; P < 0.05). When individuals were subdivided in age groups, sTNFR-1 was higher in community dwelling versus institutionalized elderly in the 60-70 age range.
Our results demonstrate that being institutionalized has an impact on levels of inflammatory markers.
This study was set up to test our hypothesis that using the Jamar dynamometer a voluntary submaximal effort has a greater variability compared to a real maximal effort, especially when there is a long interval between different measurements. We tested 32 volunteers without a history of upper limb injury or operation in our hospital, with an interval of four to five weeks between tests. Each volunteer was asked to grip first right-handed then left-handed, first with a real maximal effort and then with a submaximal effort. This test was performed twice during the same session. The same individuals were seen again one month later and were studied using the same protocol. Sensitivities and specificities for the grip test were calculated using six different criteria to indicate a submaximal effort. Repeated grip testing with a time interval of one month cannot reliably detect voluntary submaximal effort in healthy volunteers.
Despite various attempts to repair and replace injured tendon, an understanding of the repair processes and a systematic approach to achieving functional efficacy remain elusive. In this review the epidemiology of tendon injury and repair is first examined. Using a traditional paradigm for repair assessment, the biology and biomechanics of normal tendon, natural healing, and repair are then explored. New treatment strategies such as functional tissue engineering are discussed, including a functional approach to treatment that involves the development of in vivo functional design parameters to judge the acceptability of a repair outcome. The paper concludes with future directions.
Over the past 20 years, there have been numerous attempts to identify methodologies that are capable of the determination of sincerity of effort during muscle testing. The ensuing paper reviewed this literature and drew several conclusions. Injured patients and healthy volunteers do produce less force and more variable force while performing submaximal contractions than maximal contractions. However, submaximal efforts during strength testing can be reproduced and the use of force variability is not adequate to distinguish sincerity of effort. Visual examination of the shape of force output curves is also not adequate for distinguishing sincerity of effort. Furthermore, much of the research using strength ratios, difference scores, and an assortment of different parameters derived during strength testing has not established reliable and clinically useful methods of differentiating effort levels. Methods examining motion variability, radial/ulnar force output ratios, difference scores of eccentric-concentric ratios, and electromyography offer some promise, but numerous critical issues need to addressed. The use of the coefficient of variation, for example, is statistically untenable given the number of trials appropriate for clinical samples. Several studies have inadequate sample size to number of variable ratios. Many studies have questionable or at least unknown generalizability to patient samples and actual functional capacity. It is critical that other explanatory variables such as fear of injury, pain, medications, work satisfaction, and other motivational factors be considered. It is our opinion that there is not sufficient empirical evidence to support the clinical application of muscle testing to determine sincerity of effort.
This study examined patterns of grip strength when maximal and submaximal effort are applied. Using a sensor glove, 50 healthy subjects performed two different power grips. Both maximal and submaximal gripping showed characteristic patterns of strength distribution that were independent of the degree of power applied. Significant differences were also noted in the strength distribution patterns, depending on whether the grip was performed at maximal, or submaximal, strength. The small finger plays a decisive role in this. In maximal strength gripping, the total measured strength is distributed relatively evenly over all four fingers, with each finger contributing between 23% and 27% of the total strength. In submaximal strength gripping, the little finger is involved very little and only contributes between 14% and 15% of the total strength, with the remainder of the gripping distributed relatively evenly between the index, middle and ring fingers, each of which contributes between 26% and 32% of the total.
The aim was to study the relationship between impairment (function) and disability (participation) in wrist surgery, according to the WHO definitions.
The outcome of 205 wrist operations were studied. The impairment was expressed as range of motion (ROM) and gripping force, the disability as the DASH score.
There was a significant correlation between DASH and gripping force (R = 0.47). The correlation between ROM and DASH was weaker (R = 0.24).
In manual workers, shorter temporary disability periods were significantly associated with lower DASH score.
In (reconstructive) wrist surgery, impairment, disability and working status are significantly correlated. Gripping force measurement is a reliable tool for evaluation and gives a good impression of the disability. Preservation of some mobility is important, however the amount of ROM is not essential for the disability.
The purpose of the present study was to determine if the administration and interpretation of the rapid exchange grip (REG) test vary among hand therapists nationally. The REG is used to determine sincerity of effort of grip strength. There are inconsistencies in the literature regarding the administration and interpretation of the REG, as various studies use different testing protocols and diverse interpretation criteria for what constitutes a sincere effort. As a result, we expected to find a lack of standardization in the administration and interpretation of the REG in clinical practice. We conducted a random nationwide survey of 200 hand therapists. The questionnaire items regarding the administration of the REG included patient position, test instructions, handle settings, handling of the dynamometer, hand switch rate, number of repetitions, and techniques used to record the score. The items for the interpretation of the REG involved questions regarding comparative tests. We found that the REG test lacks standardized administration protocols and interpretation criteria among therapists nationwide. The lack of standardization is likely to affect the reliability and validity of the REG and to hinder the therapist's ability to accurately report its outcomes. The implications of lack of standardization in assessment techniques to the profession are discussed.
Sarcopenia is a loss of muscle mass related to aging and leads to muscle performance decline. An increase in inflammatory mediator levels, especially of IL-6, has been associated to reduced muscle strength in the elderly. The aim of the present cross-sectional study was to correlate IL-6 plasma levels with manual muscle strength (MMS) in 63 community-dwelling elderly women. (71.2+/-7.4years). IL-6 was measured using enzyme-linked immunosorbent assay (ELISA) and MMS was measured using the JAMAR dynamometer. Pearson's test was used to explore the relationship between the outcomes at the significance level of alpha=0.05. IL-6 levels (2.56+/-3.44pg/ml) and MMS (22.86+/-4.62kgf) exhibited an inverse correlation (r=-0.2673 and p=0.0373). The increase in IL-6 plasma levels possibly contributed toward the reduction in manual muscle strength among the elderly women studied.
The second edition of Graham Lister's volume on the hand is very attractive and will be of significant interest to surgeons concerned with the care of the hand as well as to appropriate hospital and medical libraries. It is not addressed to the nonspecialist.
The text is extremely well organized and includes an excellent introductory chapter on the general management of injury. Well illustrated with a variety of clinical examples, it covers the gamut from minimal repair to the maximum flap coverage and skin deficit problems.
There follows a good review on reconstruction, again with problems well illustrated with a mixture of excellent drawings and photographs of representative cases.
The examination and evaluation portions of this book are usually well done, and, as a result, it could also serve as an excellent primary text for the resident in training learning the basic elements of hand examination and evaluation in relationship
Stokes (J Occup Med; 1983;25:683-684) proposed that feigned weak hand grip can be distinguished from sincere efforts by examining force measurements for the different handle positions of the Jamar hand dynamometer. Sincere efforts yield a curvilinear relationship between grip force and handle position; feigned efforts yield a horizontal, linear relationship. The purpose of the present set of three experiments was to investigate the degree of control normal subjects have over submaximal effort and their ability to feign weakened grip. In Experiment 1 we found that subjects instructed to exert a specific amount of submaximal effort (50%) did not produce a response pattern of grip force consistent with Stokes' hypothesis. In Experiment 2 we found a linear relationship between the degree of submaximal effort and grip force for efforts of 30, 50, 70, and 90% of maximal effort. In Experiment 3 we found that subjects, with proper instruction as to the amount of effort to exert, can produce feigned submaximal efforts similar to the sincere, maximal efforts of injured people. Simple maximal grip force measurements are insensitive to the different motor strategies used in maximal and submaximal efforts and may provide little evidence for the detection of feigning.
To assist in distinguishing patients with truly decreased hand grip strength from those deliberately not gripping the dynamometer at maximal capacity, a rapid exchange grip strength test was devised and tested under four conditions. Part I, 100 normal subjects undergoing static grip testing and the rapid exchange grip test. Part II, 45 patients chosen at random from physical therapy with various hand injuries tested using only the static grip test. Part III, a blind control study on 15 normal subjects instructed to fake an injury to either the right or left hand. This group was given both the static and rapid exchange grip test. Part IV, a retrospective evaluation of 45 patients seen in a private hand practice who had both the static and rapid exchange grip test. After the dynamometer had been set to the position at which the patient had previously achieved maximal grip strength, the patient was instructed to rapidly alternate hands while gripping the dynamometer. Uninjured subjects had consistently lower rapid exchange grip test scores than previous scores at the same setting (negative rapid exchange grip). Average rapid exchange grip test scores were higher than previous scores (positive rapid exchange grip) when subjects were instructed to fake an injury with one hand. We conclude that if maximal performance has not been achieved on the static test, the rapid exchange grip shows a significant increase in grip strength on the affected side. More patients claiming worker's compensation had positive rapid exchange grips and the average score was higher than that of patients not claiming worker's compensation.(ABSTRACT TRUNCATED AT 250 WORDS)
The measurement of maximum hand grip strength in ergonomic or clinical settings has been a useful means of assessing physical characteristics, progress in rehabilitation and degree of disability in upper extremity injuries. The validity of the peak forces observed in such measurements is compromised by the requirement of subject cooperation in giving a maximum effort. Thus, an easily administered analysis of subject sincerity would improve this basic strength-testing tool. Several variables were developed for the discrimination of faking (submaximal) from sincere (maximal) grip contractions. A microcomputer-based grip force data collection system was assembled in which analog output from a Jamar hand dynamometer was sampled at 200 Hz and digitally analyzed. A total of 43 normal subjects (20 male, 23 female) were tested under sincere and faking conditions (three trials of each condition for each hand). The force-time curves of each trial were analyzed for peak and average forces and force variability. From these basic parameters five discriminator variables were developed. The frequency distribution of the sincere values for each of these variables was used to determine a criterion value for discrimination of sincere from faking trials. The five discriminators correctly detected 95.0, 92.5, 100, 100 and 97.5% of the male faking trials. Female faking was less successfully detected: 59.7, 52.2, 78.3, 71.7 and 87.0% correct detection resulted for the variables (with a 95% confidence level of correctly identifying sincerity). Multiple variable predictions improved the female faking detection up to 93.5% with little apparent decrement in sensitivity to sincerity identification.(ABSTRACT TRUNCATED AT 250 WORDS)
The objective and subjective components of industry-related injuries can lead to difficulties in diagnosis and treatment efforts. Grip strength determinations provide an objective measure that facilitates the evaluation of many occupation-related injuries. In this current study, healthy volunteers were evaluated with standard grip strength measurement and electromyographic recordings in order to characterize normal patterns. These recordings were found to be relatively uniform and reproducible.
Loss of grip is a rateable factor in the determination of permanent disability by compensation boards in some states. Malingerers, or those with psychological rather than organic disability, can voluntarily record lower grip measurements in the so-called injured hand when compared with the normal hand. The purpose here is to provide an objective method of documenting real, as opposed to fictitious, loss of grip. This method utilizes the sealed hydraulic dynamometer which has been adopted by some states as a standard grip measuring device. Its isometric and adjustable features have been utilized in this study to aid in the evaluation of the patient who complains of loss of grip with no objective recordable findings. The patient who is voluntarily attempting to demonstrate weakness of grip will apply the same minimal pressure at each of the adjustable handle positions, producing a straight line graph. In our series of patients thought to be voluntarily applying minimal grip, there has been a variance of 5 lb, or less at each of the handle positions. An objective statement can then be made that the patient did not cooperate with the test through his failure to apply maximal pressure at each dynamometer handle position as instructed.
Twenty-seven college women participated in a study to evaluate the reliability and validity of four tests of hand strength: grip, palmar pinch, key pinch, and tip pinch. Standardized positioning and instructions were followed. The results showed very high inter-rater reliability. Test-retest reliability was highest in all tests when the mean of three trials was used. Lower correlations were shown when one trial or the highest score of three trials were utilized. The Jamar dynamometer by Asimow Engineering and the pinch gauge by B&L Engineering demonstrated the highest accuracy of the instruments tested.
The purpose of this study was to establish a simple method to determine the legitimacy of a maximal voluntary grip contraction (MVGC). To achieve this, 36 subjects were randomly assigned to either a sincere (S) or faker group (F) and asked without investigator knowledge to execute either a MVGC or 75% MVGC on a specially designed grip dynamometer. The dynamometer was attached to a load cell with analog output obtained from a strip chart recorder at 50 mm X sec.-1. The force curves were evaluated empirically and also analyzed according to the following components: rate of force application (SLP), peak force (PK), average force divided by peak force (DEV) and peak force divided by body weight (WTRATIO). Average values for S and F subjects respectively were; SLP 2217 vs 1642 n X s-1, PK 499 vs 387 n, and DEV 0.91 vs 0.72. When all variable were transformed to z-scores, summed for each subject and categorized by sum into upper and lower 50% groups by gender, 87.5% of the females (N = 16) and 80% of the males (N = 20) were correctly classified as S or F subjects. Based upon a discriminant analysis performed by gender, DEV was found to be the only significant predictor for females with DEV, SLP and WTRATIO being significant predictors for the males. It was concluded that S and F subjects can be determined from the results of a maximal isometric grip strength test based upon a simple configuration analysis of an isometric force curve.
The usefulness of the rapid exchange grip test and a modification of this test, the rapid simultaneous grip test, in detecting submaximal grip efforts was evaluated. Uninjured subjects giving maximal or submaximal grip efforts were tested at grip rates of 80 and 100 repetitions per minute. Rapid exchange grip at 80 repetitions per minute yielded a sensitivity of 86% and a specificity of 97%. Rapid simultaneous grip at 80 repetitions per minute yielded a sensitivity of 81% and a specificity of 93%. Poorer sensitivities and specificities resulted when a clinical population of patients was tested. Patients who were not giving maximal efforts tended not to comply with the test protocol. The rapid exchange and rapid simultaneous grip tests do assist in detecting submaximal grip efforts; limits to these tests are emphasized.
The purpose of the present research was to investigate the use of surface EMG in assessing effort while measuring grip strength with the Jamar dynamometer. We hypothesized that sincere, maximal grip contractions could be distinguished from feigned, submaximal contractions by differences in the amplitude and frequency content of the EMG, as well as by differences in force. Healthy subjects (seven men and ten women) were instructed on different trials to give a sincere (maximal, 100%) effort or a feigned (50% of maximal) effort with the right hand. The subjects were tested at each of the five handle positions of the Jamar dynamometer. Surface EMG was obtained for the right palmaris longus/flexor carpi radialis muscles. Consistent with previous research, we found that the 50% efforts, compared to 100% efforts, showed, (1) lower peak force; (2) a slower rise to peak force; and (3) a different pattern of force measurements as a function of handle position. Feigned and sincere efforts also differed in the EMG. As hypothesized, amplitude was lower for 50% than 100% efforts. The frequency spectra of the EMG were obtained by Fourier analysis. The 50% efforts showed a higher frequency EMG than did the 100%. The results supported the hypothesis that surface EMG may provide a measure of effort in a grip strength task. Analysis of the EMG, in conjunction with force analysis, has the potential of being a valuable tool for the clinician needing to determine whether a patient is giving a sincere, maximal effort or is feigning.
In recent years researchers have devised a number of methods to detect patients who purposely exert low effort during grip evaluations. This study further defines the five-rung grip test introduced by Stokes and subsequently challenged by Niebuhr and Marion. New data are presented on the rapid exchange grip test. Data were collected on four groups of subjects (sincere normals, normals asked to feign weak grip, patients thought to be sincere, and patients suspected of low effort) using both tests. In calculating the standard deviation of the plotted line of the five-rung grip test, group membership (sincere or low effort) can be predicted. No statistical difference between peak scores on five-rung and rapid exchange grip tests in sincere subjects was found. A statistical difference between peak scores in the low-effort groups was shown. A model has been developed that can be used to categorize patients into low effort or sincere groups.
This study assessed the sensitivity and specificity of the five-position grip strength test (5PGST) for detecting feigned hand weakness in healthy volunteers. The 5PGST reliably detected feigned hand weakness in only 15% of cases. Thirty-three per cent of volunteers demonstrated an entirely normal pattern of grip strength when feigning weakness.
The rapid exchange grip (REG) test was developed to identify patients exerting insincere effort. The premise of the REG test is that a maximal, sincere effort yields a "negative REG," in which peak static grip (SG) scores are greater than peak REG scores, and that a submaximal, insincere effort yields a "positive REG," in which REG scores are greater than SG scores. There is disagreement in the literature concerning what constitutes a positive REG test, suggesting that the REG may not be a valid measure of sincerity of effort. The purpose of the present study was to investigate the validity of the REG test by examining its premise as well as its sensitivity and specificity values. The 146 uninjured subjects performed a series of randomized grip strength tests, exerting both maximal and submaximal efforts. The tests included the REG at hand switch rates of 45 rpm (REG-45) and 60 rpm (REG-60), the maximal static grip test (MSGT), and the five-rung test (5R). Our findings supported the concept of a "negative REG" for both REG maneuvers and both comparative SG tests. The concept of a "positive REG," however, was supported only when peak REG scores were compared with peak 5R scores. The authors found relatively low sensitivity and specificity values, suggesting that the REG test may not be sensitive or specific enough to effectively detect sincerity of effort. The authors discuss the likelihood that mistakes will be made when the REG test is used to diagnose sincerity of effort and the possible consequences of making such mistakes.
This study assessed the use of rapid, repeated measurement of grip strength to detect feigned hand weakness. Normal participants, performing with maximum effort or feigning hand weakness, and patients recovering from carpal tunnel surgery were asked to grip a Jamar dynamometer alternately with each hand on ten occasions.
The results showed that grip strength fatigued by an average of 23% during the test in the normal participants, 18% in participants faking weakness, and increased by 2% in the carpal tunnel decompression patients. An increase in grip strength after the first effort was found in 39% of normal participants, 52% of participants faking hand weakness and in 69% of the carpal tunnel decompression patients.
These results suggest that rapid, repeated measurement of grip strength is not a reliable discriminator of true and faked hand weakness.
Reli-ability and validity of grip and pinch strength evaluations
- V Mathiowetz
- K Weber
- G Volland
- Kashman
Mathiowetz V, Weber K, Volland G, Kashman N. Reli-ability and validity of grip and pinch strength evaluations. J Hand Surg 1984;9A:222–226.
The hand: diagnosis and indications
- Lister