Effect of Grip Span on Lateral Pinch Grip Strength

Carrie L. Shivers, Gary A. Mirka, and David B. Kaber, North Carolina State University,Raleigh, North Carolina

Repetitive, high-force pinch grip exertions are common in many occupational activ-ities. The goal of the current study was to quantify the relationship between lateralpinch grip span (distance between thumb and index finger) and lateral pinch gripstrength. An experiment was conducted in which 40 participants performed maxi-mal lateral pinch grip exertions at 11 levels of grip span distances (0, 10%, ... 100%of maximum functional lateral pinch grip span distance). The results show a signif-icant effect of lateral pinch grip span, with strength at the maximum functionallateral pinch grip span 40% higher than that found at the smallest lateral pinch gripspan considered. Between these two endpoints, strength increased monotonicallywith increasing pinch grip span. The application of these results in pinch grip de-sign criteria for both high-force and long-duration exertions is discussed. Potentialapplications of this research include the design of hand tools and controls forwhich significant force is appliedcby the user.

INTRODUCTION

Repetitive, awkward, high-force pinch gripexertions have been related to fatigue, discom-fort, and injury to the hand/wrist complex inindustrial populations. In a study of sewingmachine operators, T. J. Armstrong and Chaffin(1979) showed that operators with a history ofcarpal tunnel syndrome used pinch grips morefrequently and that the force used during thesepinch grip exertions was greater than that em-ployed by the control group (women performingthe same jobs at the time that the case groupmembers reported their symptoms). The effectsof pinch grip exertions on the intrinsic musclesof the hand were considered by Punnett andKeyserling (1987) in a study of employees in agarment shop. They found a positive correlationbetween pinch grip duration and hand pain inthis population.

In vitro work by Smith, Sonstegard, andAnderson (1977) gave further support to thedeleterious effects of pinch grips, particularlythose performed with the wrist in flexed pos-tures. Using biomechanical modeling techniques,

Cooney and Chao (1977) illustrated that themagnitude of the externally applied forces inthe pinch grip is significantly smaller than themagnitude of the resulting internal forces inthe tendons and joint contact forces. Thesestudies collectively indicate that gathering basicinformation about the biomechanical proper-ties and characteristics of pinch grip exertionsmay lead to design principles and interventionstrategies to reduce fatigue, discomfort, andinjury of the distal upper extremity.

A number of studies have considered variousfactors affecting pinch grip strength, such asage, sex, stature, body weight, wrist posture,and elbow posture (e.g., Apfel, 1986; Dempsey& Ayoub, 1996; Hook & Stanley, 1986; Lam-oreaux & Hoffer, 1995; Mathiowetz, Rennells,& Donohoe, 1985). Pinch grip span is one factorthat may be under the control of the ergonomist,and therefore understanding the relationshipbetween pinch grip span and pinch grip forcecould lead to interventions to reduce the risk offatigue, discomfort, and injury.

Two previous studies that attempted to quan-tify the relationship between pinch grip span

Address correspondence to Gary Mirka, Department of Industrial Engineering, Box 7906, North Carolina State University,Raleigh, NC 27695-7906; mirka@eos.ncsu.edu. HUMAN FACTORS, Vol. 44, No. 4, Winter 2002, pp. 569-577.Copyright © 2002, Human Factors and Ergonomics Society. All rights reserved.

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and pinch grip strength had remarkably dif-ferent results. Dempsey and Ayoub (1996) as-sessed the pinch grip strength capability of16 participants (8 men and 8 women) usinga custom-made pinch grip dynamometer. AWheatstone bridge configuration (Fathallah,Kroemer, & Waldron, 1991) employing twoaluminum bars was used to measure partici-pants' pinch grip strength. The bars were spacedat 1, 3, 5, and 7 cm and were mounted such thatit was necessary to squeeze both bars equally toachieve a valid pinch grip force measurement.Results of the lateral pinch grip strength assess-ment showed that pinch width had a significanteffect on pinch force, with the average (acrossparticipants) force increasing from I to 5 cm,peaking at 5 cm, and declining at the 7-cmgrip span.

Another study, conducted by Imrhan andRahman (1995), evaluated the pinch grip strengthof 17 male participants. This research team alsodeveloped its own pinch grip strength dyna-mometer, wherein a steel handle was attachedto a Chatillon digital push/pull force gauge. Thishandle could be slid up and down, enabling thepinch grip width to be adjusted to seven fixedwidths: 2.0, 3.2, 4.4, 5.6, 6.8, 8.0, and 9.2 cm.The participant's thumb rested on the handle,and his fingers pulled up on the force gauge toproduce a force. This testing apparatus wasmounted to a height-adjustable tripod stand,and the force measurements were read directlyfrom the Chatillon force gauge. The resultsdemonstrated that pinch width had a signifi-cant effect on force production, showing thatthe strongest grip span was the smallest span(2.0 cm) and the weakest grip span was thelargest span (9.2 cm), with a decline betweenthese points.

The results of the aforementioned two stud-ies are clearly contradictory in their descriptionof the relationship between lateral pinch gripforce and lateral pinch grip span. The specificaims of the current research were (a) to test thehypothesis that lateral pinch grip span distancehas an effect on lateral pinch grip strength, (b)to describe this relationship in terms of relativegrip span (percentage of a participant's own gripspan distance, instead of absolute grip spandistance), and (c) resolve the conflicting resultspresented in the previous work.

METHODS

Participants

The participants in this study were 40 unpaidvolunteers (19 men and 21 women) with variedbackgrounds in manual work. Participants werenot recruited based on their history of work inany particular industry or history of perform-ing specific work tasks. All were in good healthat the time of the study, and no participants hadacute or chronic musculoskeletal injuries totheir upper extremities. Each provided writteninformed consent before participation. Thirty-one of the participants were right handed. Per-tinent anthropometric data appear in Table 1.

Apparatus

The lateral pinch grip force measuringapparatus consisted of a stable wooden framesupporting a commercially available pinch gripdynamometer (B & L Engineering, model7485, Sante Fe Springs, CA; Figure 1). A pul-ley system mounted within a wooden housingwas fabricated that allowed for the measure-ment of lateral pinch grip force for pinch gripspans ranging from 4 mm (the minimum whenthe thickness of the material of the hand loopwas considered) to the participant's maximumlateral pinch grip span. In this system of pulleys,the dynamometer was mounted on an aluminumrod, allowing it to rotate freely and eliminatingthe possibility of non-pinch-grip forces influ-encing the reading of the dynamometer. Visiblemovement of the dynamometer during an exper-imental trial indicated an imbalance in the pinchgrip forces, and that trial would then be repeat-ed. Grip span of the dynamometer was changedusing the turnbuckle in the pulley system.

Pilot work indicated that a good approxima-tion of a functional, maximum lateral pinch gripspan was 70% of the distance from the inter-phalangeal joint of the thumb to the distal in-terphalangeal joint of the index finger (Figure 2)with the thumb maximally abducted. This mea-surement was taken for each participant, and70% of this value was used as the maximumlateral pinch grip span in the subsequent exper-imentation for that participant. The minimumgrip span for the experimentation was deter-mined as the minimum spacing between theloops that did not allow the loops to touch

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TABLE 1: Participant Anthropometry

Participant Mean SD Minimum Maximum

Age (years) 33.4 10.8 21 54Height (cm) 174.4 11.3 156.9 199.5Mass (kg) 77.8 19.7 50 127.3Right (cm)

Forearm circumference 27.3 3.4 21.5 33.5Hand length 18.7 1.5 15.9 22.6Hand breadth 8.4 0.8 7.0 9.9Hand breadth including thumb 10.2 0.9 8.5 12.0Hand circumference 20.4 2.0 16.8 24.3Hand circumference including thumb 23.7 2.3 19.4 29.0

Left (cm)Forearm circumference 27.0 3.5 19.9 34.5Hand length 18.8 1.6 15.8 22.8Hand breadth 8.4 0.9 7.0 10.0Hand breadth including thumb 10.2 1.0 8.4 12.3Hand circumference 20.2 2.1 16.0 24.4Hand circumference including thumb 23.4 2.3 19.0 27.6

during a maximum voluntary contraction, asthis would create an unmeasured.force causedby the physical interaction between the loops.The minimum and.maximum lateral pinch gripspan for one person is shown in Figure 3.Finally, the intermediate lateral pinch grip spanswere calculated as percentages of this range.

Dynamometer

Aluminum Rod

Experimental Task

Participants sat in front of the experimentalapparatus and assumed a whole-body postureconsistent with that suggested in the AmericanSociety of Hand Therapists (ASHT) standards(seated, elbow 900, forearm parallel to the floor,

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Figure 2. Distance between distal interphalangealjoint of index finger and interphalangeal joint of thethumb.

shoulder adducted with 00 rotation, and wristsneutrally positioned; Fess & Moran, 1981) toensure good repeatability in maximum pinchgrip exertions (Mathiowetz, Weber, Volland, &Kashman, 1984). To maintain consistency inthis posture/orientation, participants remained

stationary during the experiment, and the wood-en housing was moved back and forth betweenthe right and left hand during successive trials.Participants placed their fingers into the loopsof the apparatus and performed the sequenceof maximum voluntary pinch grip exertions.

The order of presentation of the grip spanswas randomized, and the grip spans were testedon each hand. Each maximum voluntary exer-tion (MVE) was held for 2 s; the peak forceexerted during the trial was-read from the dyna-mometer dial at completion. This method mostclosely follows that of the "sudden maximalcontraction" exertion of Williamson and Rice(1992). This method differs from that proposedby Caldwell et al. (1974) because previous pinchgrip research has shown that longer-durationexertions were not as maintainable for pinchgrip exertions (Berg, Clay, Fathallah, & Higgin-botham, 1988). There was one trial per handfor each grip span, and each trial consisted oftwo MVE pinch grips separated by a 30-s restbreak (Rice, Leonard, & Carter, 1998).

Mathiowetz (1990) found that the greatesttest-retest reliability of maximum pinch gripforce capabilities was generated when partici-pants performed three MVEs and the averageof these was used to quantify pinch gripstrength. However, pilot work for the current

Figure 3. Example minimum and maximum lateral pinch grip spans used in this study.

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study generated concerns about the time-dependent fatigue effects with the number ofexertions that were planned, so only two repeti-tions per trial were conducted, and the averageof these two peak values was determined foreach hand at each grip span. After a participantcompleted the two MVEs with one hand, the dy-namometer apparatus was moved to the otherhand and the participant performed the twoexertions as outlined. He or she then rested for2 min, during which time the experimenteradjusted the grip span of the dynamometer forthe next trial. This process was continued untilall 11 grip spans were evaluated.

Experimental Design

Independent variables. The two independentvariables in this experiment were lateral pinchgrip span and hand. The levels of lateral pinchgrip span were 0%, 10%, 20%, 30%, 40%,50%, 60%, 70%, 80%, 90%, and 100% of theparticipant's maximum lateral pinch grip span.The hand independent variable had two levels:dominant and nondominant.

Dependent variable. The dependent variablein this study was the peak lateral pinch gripforce, defined as the average of two values: thepeak force measured in the first MVE andthe peak force measured in the second MVE.

Statistical analysis. Before we conductedthe analysis of variance (ANOVA), we validat-ed the assumptions of this analysis procedureby (a) conducting a chi-square test to test forequality of the variances of the dependent varia-bles across the levels of the independent variablesand (b) by plotting the residuals as a function ofgrip span and order of run in the experiment.Once these and the other ANOVA assumptions(linearity, random process) were validated, theANOVA procedure was used to evaluate the ef-fects of the independent variables on peak later-al pinch grip force.

In this study the statistical model consistedof both fixed effects (hand and grip span) andrandom effects (participant). An expected meansquares procedure was used to determine theappropriate F ratios for evaluating the modelmain effects and interaction. Tukey's honestlysignificantly different (HSD) post hoc test wasconducted on all significant effects. Finally, a

regression analysis was conducted to establishthe relationship between lateral pinch grip span(in absolute terms - i.e., not normalized to theparticipant's maximum lateral pinch grip span)and the lateral pinch grip force. This analysiswas conducted on the data from the male par-ticipants, the data from the female participants,and the complete data set.

RESULTS

The assumptions of the ANOVA procedurewere confirmed with the chi-square test, illus-trating the homoscedasticity of the responsevariances (calculated x2 value = 12.47, x2 sta-tistic at an a of .05 = 18.31). The plots of themodel residuals revealed no systematic trendsin the residuals as a function of pinch grip spanor position within the sequence of trials.

The plot of the peak lateral pinch grip forcereveals a consistent trend of increasing lateralpinch grip force with greater span (Figure 4).This trend was seen in 36 of the 40 partici-pants, and the 4 who did not show this trendgenerally had a slight reduction in force as theywent from 80% to 100% of maximum gripspan distance.

The ANOVA showed no significant effect ofthe interaction between pinch grip span andhand (p = .5175). The main effect of pinch gripspan was a significant factor in predicting peaklateral pinch grip force (p < .0001; Tukey's HSDresults are shown in Table 2), whereas the inde-pendent variable of hand was not a significantfactor (p = .4281). This latter result agrees withthe findings of C. A. Armstrong and Oldham(1999) in their study of power grip strengthand pulp-to-pulp pinch grip strength.

The regression analysis of the nonnormalizeddominant hand data resulted in three regressionequations that can be used to predict lateralpinch grip strength in newtons (N) as a functionof lateral pinch grip span (Equations 1-3):

For males (R2 = .1 1): Lateral pinch gripstrength = 100 N + 3.93 x lateral pinchgrip span (cm). (1)

For females (R2 = .05): Lateral pinch gripstrength = 75 N + 2.41 x lateral pinch gripspan (cm). (2)

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For all (R2 = .07): Lateral pinch gripstrength = 86 N + 3.56 x lateral pinchgrip span (cm). (3)

DISCUSSION

Changes in lateral pinch grip span affect thelength-tension relationship of the participatingmuscles as well as the moment arm of the mus-cles about the multiple joints involved in gener-ating the pinch grip force. Because of thesevariable (as a function of grip span) biomechan-ical characteristics of the lateral pinch grip, it

was difficult to predict a priori how changes inlateral pinch grip span would affect lateral pinchgrip strength. This experiment was conducted toempirically derive the relationship between lat-eral pinch grip span and lateral pinch grip force,and the results indicate that pinch grip strengthincreases with greater grip spans. The principalresult of this work is that the optimal grip spansfor generating maximum pinch grip force occurfrom 80% to 100% of a person's maximum lat-eral pinch grip span, as it has been defined here(70% of the distance from the interphalangealjoint of thumb to the distal interphalangeal joint

TABLE 2: Tukey's HSD Test on Mean Grip Force (N) at Different Grip Spans

Grip Tukey GroupingSpan Mean A B C D E F

100% 111.3 X90% 107.2 X X80% 107.2 X X70% 103.3 X X60% 102.9 X X50% 100.8 X X40% 100.5 X X30% 97.8 X X20% 92.7 X X10% 88.9 X0% 80.0 X

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of the index finger with the thumb maximallyabducted).

There have been two other notable studiestesting the effects of pinch grip span on forceproduction. Dempsey and Ayoub (1996) foundthat the optimal grip span was 5 cm, whereasImrhan and Rahman (1995) found that theoptimal grip span was 1 cm. The data from thecurrent study are more consistent with that ofDempsey and Ayoub (Figure 5) and may beattributed to the similarities in the apparatusand testing procedures. First, both the currentstudy and Dempsey and Ayoub used a testingapparatus that effectively isolated the pinchgrip. Imrhan and Rahman noted that their ap-paratus did not register force when the partici-pant pushed down on the top handle of theirdynamometer, but forces exerted only on thebottom handle (lifting of the experimental appa-ratus) would register and could have influencedtheir results. Second, both the current studyand Dempsey and Ayoub positioned partici-pants according to the ASHT recommendations,whereas Imrhan and Rahman did not.

Although the trends in the results of thisstudy were consistent with those of Dempsey

and Ayoub (1996), there were some subtle dif-ferences. First, Dempsey and Ayoub did notfind a consistently increasing trend in lateralpinch grip force as a function of increasing lat-eral pinch grip span, as was found in the cur-rent study. They found that the lateral pinchgrip strength increased from 1 to 5 cm (peak-ing at 5 cm) and then dropped off at the 7-cmspan, whereas our study showed a consistentincrease in strength as grip span increased. Webelieve this difference is attributable to the dif-ferences between the absolute and relative lat-eral pinch grip span approaches. In the sampleof 40 participants in the current study, 3 par-ticipants' (7.5%) maximum lateral pinch gripspan (as defined here) was less than the 7-cmvalue used by Dempsey and Ayoub. Had these3 participants attempted to exert force at the7-cm grip span, their forces would have beendramatically lower, and this may explain thereduction found at the 7-cm level in the pre-vious work.

Arguments could certainly be made for bothmethods of assessing maximum lateral pinchgrip strength; we feel that the participant-specific (relative to participant anthropometry)

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Figure 5. Lateral pinch grip force as a function of the lateral pinch grip distance for Dempsey and Ayoub(1996), Imrhan and Rahman (1995), and the current study. Note: Data for the current study are plotted relativeto the average maximum lateral pinch grip span for the participant population and are placed on the sameaxes as data for previous studies for trend comparison purposes only; kgf = kilograms force.

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grip spans create a less ambiguous relationshipbetween grip span and grip force, whereas theabsolute grip spans have more direct applica-tion in population-based design applications.

The second difference between the two stud-ies is the difference in the absolute magnitudeof the lateral pinch grip force. We think this canbe attributed to the fact that our data reflectthe average of two instantaneous peak forces,whereas the values of Dempsey and Ayoub(1996) were calculated using the average valueacross 2-s exertions. This again reflects two validapproaches to quantifying pinch grip strength,but it also highlights an important differencethat should be considered when interpretingresults from studies of human strength.

The motivation for the current study wasfounded on observations of sewing and uphol-stery operations in the furniture manufacturingindustry during our ongoing ergonomics in-tervention project. Both jobs involve highlyrepetitive, hand-intensive activities. Workersperforming sewing tasks pinch (pulp pinch andlateral pinch grips), grasp, and tug on fabric toalign it correctly as they feed it into a sewingmachine. Upholsterers secure fabric to furnitureframes by gripping and pulling the fabric usinga lateral pinch grip with their nondominanthand and then staple the fabric to the framewith their dominant hand. Our assessment thatthese repetitive, hand-intensive tasks wereproblematic was supported by both a review ofincidence rates and a worker survey. (Methodsof Occupational Safety and Health Admin-istration Form 200 log analysis and surveysare summarized in Mirka, Smith, Shivers, &Taylor, 2002.)

A number of jobs require maximal or near-maximal lateral pinch grip forces, and theapplicability of the current study's results tothese types of tasks is clear. In addition, how-ever, our results can have implications fortasks with repetitive pinch grips that do notapproach an individual's maximum capacity.The relative amount of force (percentage ofmaximum) produced by muscular tissue hasbeen shown to affect blood flow in the tissue,which in turn affects the rate of muscularfatigue during isometric exertions (Sj0gaard,Savard, & Juel, 1988). Therefore, reducing theintensity of the muscle contraction by placing

the hand in a posture with a greater capacityillustrates another way that the results of thecurrent study can be applied.

Relating the results of the current study tothese furniture industry jobs highlights poten-tial areas of improvement. These occupationalpinch grips are at a 1- to 4-mm grip span, withonly the thickness of the fabric/leather separat-ing the two participating digits (most closelyrelated to the 0% maximum grip span mea-surement considered in this study). The resultsof this study indicate that this grip span is notthe most effective, one for generating largeforces, and it could be easily extrapolated thatlarger pinch grip spans could have the poten-tial to reduce fatigue through the reduction inthe percentage of maximum force that wouldbe required for a given pinch grip force require-ment. Therefore, it is logical that larger gripspans may be a positive design alternativewhen maximum or near-maximum pinch gripforces are required. Applying this principleposes a challenge related to dexterity and learn-ing of these pinch grips, but it may have a posi-tive effect if these challenges can be met.

A couple of limitations of the current studyshould be noted. First, and most important,pinch grip strength is only one of several issuesthat should be considered when designing atask with significant pinch grip requirements.The internal biomechanical loading patternsthat exist in each of these pinch grip spansshould be considered to gain an overall per-spective on the benefits and drawbacks of alarger lateral pinch grip span. Second, althoughthe age range of the participant population was21 to 54 years, the majority of the participantswere of college age, which limits our ability toextrapolate this response to older populations.The response of an older population is of partic-ular interest when considering how often apinch grip is necessary, not only in occupationalactivities but also in the activities of daily living.

CONCLUSIONS

Repetitive, high-force pinch grip exertionsare common in many occupational activities.The goal of the current study was to quantifythe relationship between lateral pinch grip span(distance between the thumb and index finger)

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and lateral pinch grip force. The lateral pinchgrip strength at the participant's maximum func-tional lateral pinch grip span was 40% higherthan that found at the smallest lateral pinch gripspan considered. This result may have signifi-cant implications for pinch grip design criteria,but the implications of these postures from aninternal loading perspective need to be investi-gated further.

ACKNOWLEDGMENTS

This work was supported by Grant No.R01-OH03701 from the National Institute forOccupational Safety and Health (NIOSH) anda grant from The Furniture Manufacturing andManagement Center (FMMC) at North Caro-lina State University. The contents are solely theresponsibility of the authors and do not neces-sarily reflect the views of NIOSH or FMMC.

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Armstrong, T. I., & Chaffin, D. B. (1979). Carpal tunnel syndromeand selected personal attributes. Journal of OccupationalMedicine, 21, 481-486.

Berg, V. l., Clay, D. J., Fathallah, F. A., & Higginbotham, V. L.(1988). The effects of instruction of finger strength measure.ments: Applicability of the Caldwell regimen. In F. Aghazadeh(Ed.), Trends in ergonomics/human factors V (pp. 191-198).Amsterdam: Elsevier Science.

Caldwell, L. S., Chaffin, D' B., Dukes-Dubos, E N., Kroemer, K.H. E., Laubacj, L. L., Snook, S. H., & Wasserman, D. E.(1974). A proposed standard procedure for static musclestrength testing. American Industrial Hygiene Associationloumal, 35, 201-206.

Cooney, W. P., & Chao, E. Y. (1977). Biomechanical analysis of sta-tic forces in the thumb during hand function. Journal of Boneand joint Surgery, 59A, 27-36.

Dempsey, P. G., & Ayoub, M. M. (1996). The influence of gender,grasp type, pinch width and wrist position on sustained pinchstrength. International Journal of Industrial Ergonomics, 7,259-273.

Fathallah, E A., Kroemer, K. H. E., & Waldron, R. L. (1991). Anew finger strength (pinch) gauge. International Journal ofIndustrial Ergonmics, 7, 71-72.

Fess, E. E., & Moran, C. A. (1981). Clinical assessment recom-mendations [Pamphlet]. Chicago: American Society of HandTherapists.

Hook, W. E., & Stanley, l. K. (1986). Assessment of thumb toindex pulp to pulp pinch grip strengths. Journal of HandSurgery, IIB, 91-92.

Imrhan, S. N., & Rahman, R. (1995). The effects of pinch widthon pinch strengths on adult males using realistic pinch-handcoupling. International Joumal of Industrial Ergonomics, 16,123-124.

Lamoreaux, L., & Hoffer, M. M. (1995). The effect of wrist devia-tion on grip and pinch strength. Clinical Orthopaedics andRelated Research, 314, 152-155.

Mathiowetz, V. (1990, October-November). Effects of three trialson grip and pinch strength measurements. Journal of HandTherapy, pp. 195-198.

Mathiowetz, V., Rennells, C., & Donahoe, L. (1985). Effect ofelbow position on grip and key pinch strength. Journal ofHandSurgery, 10A, 694-697.

Mathiowetz, V., Weber, K., Volland, G., & Kashman, N. (1984).Reliability and validity of grip and pinch strength evaluations.Journal of Hand Surgery, 9A, 222-226.

Mirka, G. A., Smith, C. A., Shivers, C., & Taylor, 1. (2002).Ergonomic interventions for the furniture manufacturingindustry: Part 1. Lift assist devices. International Journal ofIndustrial Ergonomics, 29, 263-273.

Punnett, L., & Keyserling, W. M. (1987). Exposure to ergonomicstressors in the garment industry: Application and critique ofjob-site work analysis methods. Ergonomics, 30, 1099-1116.

Rice, M. S., Leonard, C., & Carter, M. (1998). Grip strengths andrequired forces in accessing everyday containers in a normalpopulation. American Journal of Occupational Therapy, 52,621-626.

Sjogaard, G., Savard, G., & luel, C. (1988). Muscle blood flowduring isometric activity and its relation to muscle fatigue.European Joumal of Applied Physiology, 57, 327-335.

Smith, E. M., Sonstegard, D. A., & Anderson, W. H. (1977).Carpal tunnel syndrome: Contributions of flexor tendons.Archives of Physical Medicine and Rehabilitation, .58,379-385.

Williamson, T. L., & Rice, V. 1. (1992). Re-evaluation of theCaldwell regimen: The effect of instruction on handgripstrength in men and women. In S. Kumar (Ed.), Advances inindustrial ergonomics and safety IV (pp.675-682). New YorkTaylor & Francis.

Carrie L. Shivers is a motorcycle plant ergonomistfor Honda of America Mfg., Inc., in Marysville, OH.She received her M.S. in industrial engineering atNorth Carolina State University in 2001.

Gary A. Mirka is an associate professor of industrialengineering at North Carolina State University. Hereceived his Ph.D. in industrial and systems engi-neering at Ohio State University in 1992.

David B. Kaber is an associate professor of industri-al engineering at North Carolina State. University.He received his Ph.D. in industrial engineering in1996 at Texas Tech University.

Date received: December 28, 2001Date accepted: September 13, 2002

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