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CANADIAN JOURNAL OF OCCUPATIONAL THERAPYVOLUME 63 NO 4

CATHERINE BACKMAN LINDA E. DANIELS

KEY WORDSGrip strengthPediatricsPinch strength testing

A description of grip and pinchstrength in children aged 6 to 1 1years using the Martin Vigorimeter

ABSTRACT The vigorimeter is potentially a useful instrument for mea-suring grip and pinch strength in children. How ever, no normative or com-parative data are supplied by the manufactu rer, and only two previous studiesusing it to test children's hand strength could be fou nd in the literature. Thepurpose of this study was to collect preliminary hand strength data in childrenaged 6 to 11 years. Spherical grip, tip pinch an d tripod pinch strength weremeasured in 134 children. Graphs displaying the results suggest that, on aver-age, strength increases with age, boys are stronger than girls, and the righthand is often (but not always) stronger than the left. While far from produc-ing norms, this study did demonstrate that the vigorimeter has utility as aninstrumen t for measuring grip an d pinch strength in children, an d providedsome preliminary baseline data to assist clinicians in judging the results ofhand strength tests.RESUMEe vigorimtre peut tre un instrument utile pour mesurer laforce de prhension grossire et la force de prhen sion fine chez les enfants.Cependant, le fabricant ne fournit pas de donnes normatives ou com parativeset on ne trouve dans la littrature que deux tudes dans lesquelles l'instrumenta t utilis pou r valuer la force de prhension des enfan ts. Le but de cettetude tait de recueillir des donnes prliminaires sur la force de prhensiondes enfants gs de 6 11 ans. La force de la prise palmaire sphrique, desprises digitales et des prises tridigitales a t me sure chez 134 en fants. Lesrsultats prsents dans les graphiques suggrent qu 'en gnral la force aug-mente avec l'ge, les garon s sont plus forts qu e les filles et la main droite estsouvent (m ais ce n'est pas toujours le cas) plus forte que la gauche. Loin deproduire des normes, cette tude a toutefois dmontr qu e le vigorimtre estun instrument utile pour mesurer la force de prhension grossire et la forcede prhension fine chez les enfants. l 'tude fo urnit galement quelqu es don-nes de b ase prliminaires qui aideront les cliniciens ap prcier les rsultatsdes tests sur la force de prhension.

atherine Backman, M.S., 0.T.(C)is Senior Instructor, Division of

ccupational Therapy, School ofRehabilitation Sciences, TheUniversity of British C olumbia, T325-2211 Wes brook Mall, Vancouver,BC V6T 2B5.

inda Daniels, M.A., 0.T.(C) is solePort Aberni, BC. At the time of this

as an Ins t ructor, DivisionOccupational Therapy, School of

ehabilitation Sciences, The Univer-of Brit ish Columbia.

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C. Backman & L. DanielsGrip and pinch strength are frequently measuredby occupational therapists when assessing handfunction in children to help identify level of devel-opment or degree of impairment, to establish treat-ment needs, an d to measure treatment outcomes.For these clinical purposes it is necessary to haveinstruments, procedures and normative data thatare reliable and valid. Most of the publishedresearch dealing with grip and pinch strength mea-surement has focused on adults, but there isincreasing interest in establishing reliable an d validnormative data for children.

Measurement an d procedural problems of asimilar nature have been identified in both theadult and pediatric grip strength literature, namelydifferences in the following: (a) the instrumentsused, ( 1 3 ) the instructions used, (c) the position ofthe subjects and the instruments, (d) the numbersof trials, and (e) the calculation methods used toconstruct the various forms of normative data. As aresult, at least three requirements for the measure-ment of grip an d pinch strength to be reliable, validan d clinically usefu l have emerged in author rec-ommendations: (a) accurately calibrated test instru-ments which are commercially available, (b) stan-dardized test procedures, and (c) normative data forcomparison and interpretation of the results. Inaddition, it has been n oted that most comm erciallyavailable instrum ents were developed fo r adults,an d therefore are too large and too heavy fo r chil-dren's small hands (Robertson & D eitz, 1988).A search of the literature identified 13 stud -ies which examined grip and pinch strength in chil-dren. These papers were reviewed w ith respect tothe three criteria ou tlined above.

INSTRUMENTATIONThe Jamar dynamometer was used in four of thenine studies which m easured grip strength in chil-dren. However, the handle position was not consis-tent across the studies. The third or middle positionwas used by Bowman and Katz (1984 ), the secondposition by Mathiowetz, Wiemer an d Federman(1986), while Fu llw ood (1986) and A ger, Olivettand Johnson (1984) adjusted the handle positionrelative to the size of the child's hand. A Stoeltingdynamometer, adjusted for hand size, was used intwo studies (Montoye & Lamphiear, 1977; Imrhan& Loo, 1989). Other instruments were a strain

gauge (Newman, Pearn, Barnes, Young, Kehoe, &New man, 1984), the M artin Vigorimeter with thsmallest size bulb (Robertson & D eitz, 1988; LinkLukens & Bush, 1995), a modified sphygmomanometer (Dunn, 1993) , and a Collins ellipticadynamometer (Montpetit, Montoye & Laeding1967). Six of the studies measured p inch strengthThe Preston pinch gauge w as used in tw o of them(Ager et al., 1984; Imrhan , 1989), the Pinsco or B& L Engineering gauge was used in two (Fullwood1986; Mathiowetz et al., 1986), and a standard buunspecified pinch gauge was used in tw(Bu rmeister & Flatt, 1975; W eiss & F latt, 1971).

STANDARDIZED TEST PROCEDURESUniform procedures and test positions were reportedly used w ithin each study b ut not across studieswith one exception: Link, Lukens and Bush (1995essentially replicated Robertson and Deitz's 1988study of spherical grasp in preschool childrenPositioning variations included the position of thsubjects (seated, standing, position of the arm anhand, position of the instum ent within the hand)the type of pinch or grip measured, the number otrials, and the order of testing. These variables havbeen demonstrated to influence grip an d pincmeasurement in adults (Mathiowetz, Rennells &Donahoe, 1985). For example, the position of thelbow has been shown to result in significantly different grip strength scores (Kuzala & Vargo, 1992an d flexing the non-active fingers during pinchresults in significantly higher pinch strength thanwhen the fingers are extended (Hook & Stanley1986). The use of standardized verbal instructionan d demonstration is believed to affect performance on evaluation tests, and is considered aimportant factor con tributing to adequate test relability (Davis, 1974). The use of standardizeinstructions w as clearly identified in half of thstudies (Bow man 8 c Katz, 1984; Dunn, 1993; Linet al., 1995; M athiowetz et al., 1986; Monpetit eal. 1967; Robertson & D eitz, 1988), but not specified in the remaining papers. Future studies ohand strength testing wou ld be more meaningfulmore easily reproduced, and more useful for clinical interpretation of test scores if standardized procedures were used and specified. The America

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Society of Hand Therapists produced recommen-dations fo r hand function tests to promote thispractice (Fess & M oran, 1981).

AT I V E DATASome form of normative data was included in all ofthe studies. However, there was no consistencyacross studies regarding the unit of measurementused, method of calculating individual scores (e.g.,single trial, mean of three trials), types of normativescores (e.g., use of mean, standard deviation, per-centiles), or age intervals used to display norms.The similarities and differences fo r hand strengthare summarized in Table 1.The lack of consistency regarding instru-ments, test procedures and normative data contin-ues to limit the reliability, validity an d clinical use-fulness of grip and pinch strength measures fo rchildren. In spite of the numerous methodologicaldifferences, Dan iels and Backman (1993) identi-fied a number of trends in the development ofhand strength which did emerge from these studies:(a) strength increases with age, (b) boys are strongerthan girls, (c) increases in strength are parallel forboys and girls until adolescence when boys'strength increases rapidly while girls' strengthincreases gradually, (d) the right hand is strongerfo r right handers while findings for left handers areinconsistent, and (e) height and weight are signifi-cantly correlated with grip an d pinch strength.The question of instrument suitability is acritical variable which could influence the entireissue of the development of strength norms fo rchildren. Robertson and Deitz (1988) suggestedthat most commercially available dynamometersare too large and too heavy fo r children's smallhands. Instrument size an d weight could be evenmore important factors to consider when attempt-ing to measure strength in children with handimpairments. These same authors point out thattraditional dynamometers require the use of acylindrical grasp pattern, while occu pational thera-pists are more likely to be interested in measuringthe more function-related spherical grasp, whichincorporates thumb opposition. As a result,Robertson and Deitz (1988) chose to use theMartin Vigorimeter (also known as theDynamometer Pinch Gauge Combination) to

measure the sph erical grip strength in children agedthree to five years old. Their study cited an unpub-lished study (Level, 1984, cited by Robertson &Deitz, 1988) that used the vigorimeter to measurespherical grip strength in children aged six throughnine years, as the apparent impetus for their study.Subsequ ently, Link et al. (1995) also used the vig-orimeter to test preschool children. NeitherRobertson and D eitz nor Link et al. used the vig-orimeter to measure pinch strength in children. Todate, there are no published vigorimeter pinchstrength norm s fo r children or adults.The purpose of the present study therefore,was to establish preliminary spherical grip, tippinch and tripod pinch strength performance datafo r children 6 through 11 years of age, using theMartin Vigorimeter, and to describe the effects ofage an d gender on hand strength as measured bythis instrument.

METHODSAMPLEThe sample consisted of 134 children, 68 girls and

66 boys, 6 to 11 years of age. Age w as determinedby self-report (i.e., How old are you?). The onlyexclusion criteria was recent hand pain or injury,but none of the volunteers indicated this to be thecase. Forty-seven su bjects were recruited in shop-ping malls and comm unity centres in the GreaterVancouver area of British Colum bia. The remain-ing subjects volunteered at a rural elementaryschool on Vancouver Island, British Columbia.Nine children stated they were left-handed.Permission to approach children was granted by theaccompanying parent or caregiver in the case ofcommunity test sessions and by the principal in thecase of the school. A simplified consent form wasused an d children signed their own forms. Thestudy was approved by the University of BritishColumbia Behavioral Sciences ScreeningCommittee for Research and Other StudiesInvolving Hu man Su bjects.

INSTRUMENTThe Martin Vigorimeterl is a pneumaticdynamometer with three sizes of rubber bu lbs (cir-cumferences of 19 cm, 16.5 cm and 13.5 cm) to'Although the vigorimeter used in this study was purchased through the J.A. Prestoncatalogue, the enclosed instructions describing the instrument and its calibration arelabeled Elmed Incorporated, 60 West Fa y Avenue, Addison, Illinois 60101.

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Table 1Summary of 13 Studies of Hand Strength Norms for Childrenfirst authorndivetricamplegeorms descr ibed by :& yearcoreizeangegeender vs L handcore typeAgeringlebs74-12 yrsesesesable of means & SD1984rial1-yr intervals)or each of grip & 3 pinchesBowmanean of kg &53-9 yrsesoesable of means & SD for grip1984 trialsbs1-yr intervals)Burmeisterotg741-8th grade nooesquations to predict strength1975tatedf 5 different pinches based

on hand size

Dunnean of mmHg73-7 yrsesoesable of means & SD for grip1993 trials6-mo intervals)Fullwoodingleg &14-12 yrsesesesable of means &SD for each1986rialbs1-yr intervals)f grip & 6 different pinchesImrhan trialsg2-12 yrsoesoable of means & SEM, box1989lots, for grip an d 6 pinchesLinkea n ofP a25-6 yrsesoesable of means & SD fo r grip1995 trials6-mo intervals)Mathiowetzea n ofbs71-19 yrsesesesable of means & SD for grip1986 trials2-yr intervals)Montoyees t ofg0190-19 yrsesesoable of means, SD &1977 trials1-yr intervals)ercentiles for gripMontpetit trialsg*08-17 yrsesesoraphed mean scores for grip19671-yr intervals)Newmanea n of417-18 yrsesesoraphed percentiles for grip1984 trials1-yr intervals)raphed mean grip relative(2 R, 2 L)o height and weightRobertsonean ofP a80-5.5 yrsesoesable of means 8 < SD for grip1988 trials6-mo intervals)Weissum of 5 no t98-13 yrsooominant vsable of correlations of hand1971ifferentpecifiedength and strength pinchesNote: * this author recorded s trength in lbs an d later converted the scores to kg

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accommodate different hand sizes or functions.Figure 1 The pressure exerted_ on the rubber bu lb is record-ed on a calibrated m eter, with a needle that remainsin position indicating maximu m pressure exerteduntil released by the observer. According to theinstrument specifications enclosed with the instru-65 ment, all vigorimeters manu factured prior to 1976were calibrated in kilopont (kpt), a parameter fo rworkload, bu t following international standardiza-tion of parameters by the World HealthOrganization, the calibration w as changed to bar60 an d kilopascals (kPa) in 1976. Pascal is "the SI unitof pressure, which corresponds to a force of onenewton [N ] per square meter; symbol, Pa" (M iller-Keane Encyclopedia & Dictionary of M edicine,Nursing & Allied Health, 1992, p. 1116). Since all

three measurement units are almost identical,

Group means for grip strength by age, gender and hand.

I I_IL_601Age (years) PROCEDURESFor each test of grip an d pinch strength subjectswere positioned following the recommendations ofthe American Society of Hand T herapists (ASHT):seated with the shoulder adducted an d neutrallydr55xcept for the placement of a decimal point, thishas led to confusion in recording the unit of mea-surement and the labeling of results [1 kpt/cm2 =98.1 kPa (Thorngren & Werner, 1979); 1 bar =1.019 kpt/cm2 (Elmed Inc.)]. Recording results in50Pa perinits the use of whole num bers, thus the kP ascale was used in this study.Solgaard, Kristiansen and Jensen (1984)used a universal testing machine to evaluate theaccuracy of the vigorimeter under a range of forcesfrom 50 to 500 N (in increments of 50 N) which45 resulted in an almost perfectly linear curve, sug-gesting consistency regardless of the amount offorce applied to the rubber bulb. They also report-ed low variation coefficients of 6-7/o in a clinicalstudy of 10 0 adults (45 men and 55 women), andfound the vigorimeter to be more precise than40 spring-loaded dyn amom eters. Jones et al. (1991),A Boys, RHn a study of non-disabled adults an d adults withrheumatoid arthritis, reported very good test-retestA Boys, L HO Girls, RH Girls, L Heliability, r > 0.91, and inter-rater reliability,r > 0.97. Percent agreement of 98% or better35depending on the rater pair) was established by the first author and two research assistants prior to col-/ecting the data for the present study.REVUE CANADIENNE D'ERGOTHRAPIE VOLUME 63 * NO 438 OCTOBRE 1996

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45

40

35

30

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20Boys, RHBoys, L H0 Girls, RHGirls, L H15

^


rotated, elbow flexed to 90, and the forearm an dwrist in neutral position (Fess & Moran, 1981).Gradu ated benches were used to ensure that eachchild's feet were supported on the ground.Spherical grip strength was measu red withthe thumb opposed to the fingers around the medi-um bulb. Pinch was measured w ith the small bulb.Tip pinch was defined as the opposition of thumbtip to index finger tip, and tripod pinch strength(three-point palmer pinch, three-jaw-chuck pinch)was defined as the opposition of thumb pad to thepads of the index and middle fingers. The order oftesting w as standardized, and started with the righthand and alternated betw een h ands, resulting inrest periods between trials of approximately 15 sec-onds. Grip strength was measu red first, followed bytip pinch strength then tripod pinch strength.Standard instuctions were given, as follows:(a ) fo r grip strength: "I am going to measure

your grip strength. You w ill have three tries tosqueeze this bulb as strongly as you can. Keepyour arm in this position. Are you ready?Go."(b ) fo r tip pinch strength: "I want you topinch the bulb like this (demonstrated) u singthe tips of your thum b and index finger. Youwill have three tries to pinch as strong as yo ucan. Keep your arm in this position. Are yo uready? Go."(c ) fo r tripod pinch strength: "I w ant you topinch this bulb like this (demonstrated) withthe pads of your thumb, index and middlefingers. You w ill have three tries to pinch asstrong as you can. Keep your arm in thisposition. Are you ready? Go."

Subsequent verbal instructions fo r all threemeasu res included saying "Relax" after recordingthe vigorimeter score and moving on to the nexttrial with the statement "Are you ready for the nexttrial? Go." The mean of three trials (Fess & Moran,1981) of each hand was used as the child's score forgrip, tip pinch an d tripod pinch.

RESULTSDescriptive data for boys and girls in one year inter-vals are shown in Tables 2, 3 an d 4. The meanscores by age, gender and hand are graphically dis-played in Figures 1 an d 2. Because there are only 10

Figure 2Group means for tip pinch strength and tripod pinch strengthby age, gender and hand.

60 11Age (years)

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Table 2Descriptive Statistics for Grip Strength ( k P a ) in Boys and Girls Aged 6 to 1 1 Years.Age &inimumaximumeantd. dey.edianGender

6 Yearsboys1199960004girls744864527 Years boys29117867girls98426446

8 Yearsboys03368453girls76795533

9 Yearsboys31854846girls165454233310 Years boys3041085399girls56558683

1 1 Yearsboys946363229girls6145698427Note: R = right hand; L = l e f t hand.to 14 children in each group, the sample was con-sidered too small to yield meaningfu l results withfurther statistical analysis. However, the grapheddata illustrate lesser differences between children atsix and seven years of age that appear to becomemore substantial by age 11 . Among the childrentested, boys were generally stronger than girls andthe right hand was often, bu t not always, strongerthan the left hand.

ISCUSSIONAlthough hand strength typically increased withage, the grip strength of 10-year-old girls droppedalmost to the level of 8 year-old-girls. Similarly, thetripod pinch strength for 9 and 10-year-old girls

also dropped below that of 8-year-old girls. Giventhat each age group consisted of only 10-14 chil-dren, the most likely explanation for the dips in thegraphs is one related to small, non-random sam -pling. None of the other studies reported in the lit-erature identified a similar trend. This result illus-trates the importance of understanding the sourceof norm ative data before making judgments aboutindividual children's test results in the clinical set-ting. The data from this study are insufficient to beused as norms, even though they may provide pre-liminary baseline information to aid in the inter-pretation of children's hand strength scores on thevigorimeter.

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Table 3Descriptive Statistics for Tip P inch Strength ( k P a ) in Boys and Girls Aged 6 to 1 1 Years.Age ( y r s )inimumaximumea ntd. dev.edian& Gender6 Years

boys21289876girls013467777 Years boys62340900girls774300018 Years

boys11079998girls656320109 Years boys64021990girls1185093110 Years boys85436464girls23274252

1 1 Yearsboys41423231girls12981921Note: R = right hand; L = lefi hand.The manufacturer's insert with the MartinVigorimeter suggests the following normal valuesfo r grip strength in healthy children:

adolescents 40 to 120 kPa;7 years old 40 to 80 kPa;5 years old 30 to 70 kPa;3 years old approximately 12 kPa.In the present study, neither 7-year-old boys nor

girls produced group m eans within the range stat-ed by the manu facturer, although 40 to 80 kPadoes describe the 8 to 11- year- olds. Also, the cur-rent 6 and 7-year-olds' scores, with means rangingfrom 34 to 39 kPa, are lower than those reported byRobertson and D eitz (1988) for 5-year-olds (mean42 kPa, standard deviation 9). The 3-year-olds in

the Robertson and Deitz study also outperformedthe manufacturer suggested value of 12 kPa, withmean of 23 kP a for the 68 children aged 3 to 3.5years old, and 28 kPa for the 77 children aged 3.51to 4 years old. How ever, the 3 to 5-year olds testedby Link et al. (1995), with group m eans of 13 to 3kPa, are more in line with the trends emerging ithe present study. Age comparisons may not beaccurate since the preschool children were testedusing the smallest bulb, and school aged childrewere tested using the medium bulb. Parentheticallyit is important to note that the medium bulb is toolarge for pre-schoolers' small hands. C learly, if thvigorimeter is to be used fo r estimating the presence or absence of impairment with regard to han


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4Statist ics tor Tripod P inch Strength ( k P a ) in Boys and Grls Aged 6 to 1 1 Years.

l y r s )inimumaximumeantd. dev.edianGenderYears

boys4 -0373920girls89338595Years boys41260099girls53761213Years

boys66293232girls35476463

Yearsboys91136778girls01024252Years boys18069696girls47573221

1 Yearsboys32163949girls27851625R = right hand; L = left hand.strength, normative data beyond those valuesenclosed with the instrument and in the three avail-able studies are required. This does not, however,

preclude the vigorimeter's use as an instrum ent forcollecting baseline performance and registeringchange over time, since it has been show n to pro-duce consistent and reliable data (Jones, et al.,1991; Solgaard, et al., 1984).

Robertson and D eitz (1988) and Link et al.(1995) found no significant difference in the gripstrength of boys and girls in the age groups theystudied (3 to 5.5 years), althou gh m ost other stud-ies of hand strength have indicated that boys arestronger than girls (Daniels & Backman, 1993).The results of the present study suggest that genderdifferences may begin to emerge when children

approach elementary-school age, just beyond theage group evaluated in the Robertson and D eitz,an d Link et al. studies. However, in some of the agegroups (in particular, the tip pinch strength resultsgraphed in Figure 2) the gender difference is of verysmall magnitude in the 6 to 11-year-olds tested,suggesting that further evidence is required befo reit is known what, if any, effect gender has on handstrength in children.

LIMITATIONSAlthough height and w eight (Daniels & Baclunan ,1993) and hand size (Link et al., 1995) have beensignificantly correlated with hand strength, thesevariables were not included in the present study. Iti s possible that children's physical size rather than

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their age may be a more appropriate way to catego-rize normative data for strength measures.Use of a convenience sample, and a smallon e at that, limits the generalizability of the find-ings. The m agnitude of this limitation is illustratedin part by comparing the results of the grip strengthstudies by Robertson and Deitz (1988) with Link etal. (1995). The former also used a conveniencesample while the latter used a random samplestratefied by age, ethnicity and family income.When age group means were plotted on a graph,the pattern of the curves was very similar, but thechildren from Robertson and Deitz's study (white,middle-class, Seattle residents) were con sistentlystronger than children in Link et al's stratefied ran-dom sample from Kalamazoo preschools, by about10 kPa. Until other 6 to 11-year-old children aretested, it is not know n if the the convenience sam-ple tested in the present study is representative ofother school-aged children or not.N o attempt was made to explore the rela-tionship between hand strength and the broaderdomain of occupational performance. Althoughhand strength testing may be useful to identifypresence or absence of impairment at the level ofphysical components, its impact on the child's per-formance of school, self-care or leisure activitiesrequires additional assessment.

S U MMA R YClinical assessment recommendations put forth bythe ASHT for testing adults were applied to thepositioning of children and use of the vigorimeterwithout difficulty. The scores of 134 children aged6 to 11 years provides some baseline data for thegrip, tip pinch an d tripod pinch strength of typicalchildren using the vigorimeter, how ever furtherresearch with larger, random sam pling is requiredto provide useful norms. The results obtained w iththis sample support trends identified in the litera-ture, such as strength increasing w ith age and a ten-dency for the right hand to be stronger than theleft. Further, there is some suggestion that genderdifferences in hand strength just begin to emerge inthe age group tested, with boys starting to haveaverage strength scores higher than girls. Handstrength testing can b e a useful part of the occupa-

tional therapist's assessment of physical components, provided standardized procedures are useand data, such as norms, are available to aid iinterpretation of results.REFERENCESAger, A.C., Olivett, B.L. & Johnson, C.L. (1984). Grasp an

pinch strength in children 5 to 12 years old. AmericaJournalof Occupational Therapy, 38, 107-113.Bowman, 0.J. & Katz, B. (1984). Hand strength and pronextension in right-dominant 6 to 9 year olds. AmericaJournalof Occupational Therapy, 38, 367-376.Burmeister, L.F. & Flatt, A.E. (1975). The prediction of hanstrength in elementary school children. Hand, 7, 123-127

Daniels, L. & Backman, C. (1993). Annotated bibliography: Grian d pinch strength norms fo r children. Physical anOccupational Therapy in Pediatrics, 13, 81-90.

Davis, EB. (1974). Standards. for educational and psychological testWashington, DC: American Psychological Association.Dunn, W (1993). Grip strength of children aged 3 to 7 yearusing a modified sphygmomanometer: Com parison of typical children and children with rheumatic disorders

American Journalof Occupational Therapy, 47, 421-428.Fess, E.E. & M oran, C.A. (1981). Clinical assessment recommendations. American Society of Hand Therapists.

Fullwood, D. (1986). Australian norms fo r hand an d fingestrength of boys and girls aged 5-12 years. AustraliaOccupational Therapy Journal, 33, 26-36.Hook, WE. & Stanley, J.K. (1986). Assessment of thumb to indepulp to pulp pinch grip strengths. Journalof Hand Surgery11B, 91-92.

Imrhan, S.N. & Loo, C.H. (1989). Trends in finger pincstrength in children, adults, and the elderly. Human Factor3/, 689-701.Jones, E., Hanly, J.G., Mooney, R., Rand, L., Spurway, PEastwood, B .J., & Jones, J.V. (1991). Strength and functioin the normal and rheumatoid hand. Journal Rheumatology, 18, 1313-1318.Ku zala, E.A. & Vargo, M .C. (1992). The relationship betweeelbow position and grip strength. American JournalOccupational Therapy, 46, 509-512.Link, L., Lukens, S., & Bush, M.A. (1995). Spherical gristrength in children 3 to 6 years of age. American JournalOccupational Therapy, 49, 318-326.Mathiowetz, V., Rennells, C. & Donahoe, L. (1985). Effect oelbow position on grip and key pinch strength. JournalHand Surgery 10A, 694-697.

Mathiowetz, V. W iemer, D.M. & Federman, S.M. (1986). Griand pinch strength: Norms for 6- to 19-year olds. AmericaJournalof Occupational Therapy, 40, 705-711.

Miller-Keane E ncyclopedia & Dictionary of Medicine, Nursing &Allied Health. (1992). (5th ed.). Philadelphia: WBSaunders.


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. Backman & L. Dc-inielsD.E. (1977). Grip an d arm strengthin males and females, age 10 to 69. Research Quarterly, 48,

109-120.aeding, L. (1967). Gripstrength of school children, Saginaw, Michigan: 1899 and1964. Research Quarterly, 38, 231-240.man, D.G., Pearn, J. , Barnes, A., Young, C.M., Kehoe, M. 8cNewman, J. (1984). Norms fo r hand grip strength. Archivesof Disease in Childhood, 59, 453-459.J. (1988). A description of grip strengthin preschool children. American Journal of OccupationalTherapy, 42, 647-652.

Solgaard, S., Kristiansen, B. & Jensen, J.S. (1984). Evaluation ofinstruments for measuring grip strength. Acta OrthopedicaScandinavica, 55, 569-572.

Thorngren, K.G. tic Werner, C.O. (1979). Normal grip strength.Acta Orthopaedica Scandinavica, 50, 255-259.W eiss, M.Wlatt, A.E. (1971). A pilot study of normal chil-dren: Pinch strength and hand size in the growing hand.American Journalof Occupational Therapy, 25,10-12.

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